WO2016117833A1 - Noise control method - Google Patents
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- WO2016117833A1 WO2016117833A1 PCT/KR2015/013779 KR2015013779W WO2016117833A1 WO 2016117833 A1 WO2016117833 A1 WO 2016117833A1 KR 2015013779 W KR2015013779 W KR 2015013779W WO 2016117833 A1 WO2016117833 A1 WO 2016117833A1
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1783—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
- G10K11/17833—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions by using a self-diagnostic function or a malfunction prevention function, e.g. detecting abnormal output levels
- G10K11/17835—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions by using a self-diagnostic function or a malfunction prevention function, e.g. detecting abnormal output levels using detection of abnormal input signals
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1781—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
- G10K11/17813—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms
- G10K11/17817—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the acoustic paths, e.g. estimating, calibrating or testing of transfer functions or cross-terms between the output signals and the error signals, i.e. secondary path
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17853—Methods, e.g. algorithms; Devices of the filter
- G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1787—General system configurations
- G10K11/17879—General system configurations using both a reference signal and an error signal
- G10K11/17881—General system configurations using both a reference signal and an error signal the reference signal being an acoustic signal, e.g. recorded with a microphone
Definitions
- the present invention relates to a noise control method.
- noise reduction methods include noise source control, passive noise control, and active noise control (ANC).
- the noise source control method is a method of removing the noise source, which is the first sound source that causes the noise, or processing the noise to be reduced.
- the noise source control method is to remove any vibration source that causes noise, if it can be removed, and redesign or install an insulation device to reduce the vibration as much as possible.
- the passive noise control method is a method of reducing noise by placing a sound absorbing material or a sound insulating material in a path through which noise is transmitted from a noise source.
- a passive noise control method is to install a sound barrier to block road noise.
- the active noise control method is a method of reducing noise in a desired target area (or target point) by using a second control source or sound sources.
- the active noise control method is to sense the noise measured by the microphone, and to control the noise by outputting the opposite noise signal through the speaker.
- Such active noise control methods include an open-loop control, an active noise control method using an FXLMS (Filtered-X Least Mean Square), an FXNLMS (Filtered-X Normalized Least Mean Square), and a FULMS (Filtered-U Recursive Least Mean Square) algorithm.
- FXLMS Frtered-X Least Mean Square
- FXNLMS Feiltered-X Normalized Least Mean Square
- FULMS Feiltered-U Recursive Least Mean Square
- the open-loop control is effective when the system is very stable, but the majority of the system has an uncertainty (uncertainty), the repeatability is poor and thus the noise reduction performance may be reduced.
- the conventional active noise control method In environments where the temperature or pressure around the system changes drastically, the speed of sound changes. This is because the delay time of the system is changed, and in this environment, the conventional active noise control method has a problem in that an error occurs between the noise signal and the opposite noise signal and thus the noise cannot be reduced.
- the additional path transfer function model is updated by a LMS method using an error signal measured by a microphone.
- a noise signal is detected by the first microphone, an error signal is detected by the second microphone, and the reference signal by the detected noise signal is filtered by the additional path transfer function initial model so as to generate a reference noise.
- a signal is generated, and the reference noise signal is multiplied by an error signal and a convergence element to generate an improved adaptive filter, a new adaptive filter is generated by adding the improved adaptive filter and the adaptive filter, and the noise signal is filtered by the new adaptive filter to produce the opposite noise. Generated signal.
- the additional path transfer function is changed due to the uncertainty in the system, causing an error between the additional path transfer function model and the actual transfer function.
- the system can stably reduce noise, but if the additional path transfer function is changed outside the stability condition of the system, It lowers the stability and convergence of the noise control, and may also cause problems that the system may diverge.
- Non-Patent Document 1 SEN M. KUO AND DENNIS R. MORGAN, “Active Noise Control: A tutorial Review” PROCEEDINGS OF THE IEEE, VOL. 87, NO, 6, JUNE 1999
- the embodiment is a noise control that calculates the delay time of the system in an environment where the ambient temperature or pressure changes, and controls the noise by compensating the difference between the previously measured additional path transfer function model and the actual transfer function. It is an object to provide a method.
- a noise control method includes: a first output step of receiving a reference signal, generating a first counter noise signal, and outputting a first sound with respect to the first counter noise signal; A first sensing step of sensing a first noise while the first sound is output; A second output step of generating a second counter noise signal by adding an additional signal to the first counter noise signal when the first noise is detected, and outputting a second sound with respect to the second counter noise signal; A second sensing step of sensing a second noise while the second sound is output; And when the second noise is detected, comparing the additional signal with a signal caused by the second noise to generate a delay time error signal, and generating a third counter noise signal using the delay time error signal. And a third output step of outputting a third sound with respect to the third counter noise signal.
- the reference signal is applied to the first adaptive filter to generate the first counter noise signal
- the third output step is an additional path transfer function updated by the delay time error signal.
- the first output step before the first output step, generating a white noise signal, and outputting a fourth sound for the white noise signal; And generating an initial model of the additional path transfer function using the white noise signal and the transmission signal of the fifth sound detected while the fourth sound is output.
- the delay time error signal can be generated by comparing with the additional signal.
- the frequency of the reference signal may be analyzed, and the first counter noise signal may be generated by selecting a frequency to be controlled among the frequencies of the reference signal.
- the additional signal may be a frequency signal other than the audible frequency.
- the first microphone includes a first sample, a second sample,... , First reference noise for the n th sample, second reference noise,... , N-th reference noise
- the second microphone detects the first noise, the second noise,... A sensing step of detecting an n-th noise;
- the nth error signal is transmitted, the first additional signal, the second additional signal,.
- An additional signal generating step of generating an nth additional signal The first reference signal, the second reference signal,... The n th reference signal, the first error signal, the second error signal,... , The nth error signal, the first additional signal, the second additional signal,... A first opposite noise signal, a second opposite noise signal,... A counter noise signal generating step of generating an n-th counter noise signal; And the first counter noise signal, the second counter noise signal,... The nth reverse noise signal, the first additional signal, the second additional signal,... , The first sound of the first counter noise signal, the second sound of the second counter noise signal by adding the n-th additional signal; And an output step of outputting an n th sound with respect to the n th counter noise signal.
- the first additional signal, the second additional signal,... The nth additional signal, the first error signal, the second error signal,... Comparing the n-th error signal to obtain a first delay time error signal, a second delay time error signal,.
- Generating an updated additional path transfer function model by updating an initial model of the additional path transfer function of the additional path transfer function model in real time using the n th delay time error signal, and generating the first reference signal and the second reference signal ,... Applying the n th reference signal to the updated additional path transfer function model to generate a first reference noise signal, a second reference noise signal,... A reference noise signal generating step of generating an n-th reference noise signal; The first error signal, the second error signal,... The n th error signal may be converted into the first reference noise signal, the second reference noise signal,.
- a first improvement adaptation filter, a second improvement adaptation filter Generate an nth improvement adaptation filter, the first improvement adaptation filter, the second improvement adaptation filter,.
- the second adaptive filter, the third adaptive filter An adaptive filter generating step of generating an n + 1th adaptive filter; And the first reference signal, the second reference signal,... The n th reference signal is applied to the second adaptive filter, the third adaptive filter,. , After applying to the n + 1th adaptive filter, a first additional signal, a second additional signal,. , By adding the n-th additional signal, the first opposite noise signal, the second opposite noise signal,... And a reference signal applying step of generating the nth counter noise signal.
- the adaptive filter generating step includes: the second error signal; , The second adaptive filter, the third adaptive filter,... In a direction in which the square of the n-th error signal is minimized.
- the n + 1th adaptive filter may be generated.
- the sensing step before the sensing step, generating a white noise signal, and outputting a sound for the white noise signal; And generating the additional path transfer function initial model using the transfer signal of the sound and the white noise signal detected by the second microphone.
- the delay time error signal generating step may include the first error signal, the second error signal,... After the high pass filtering the n-th error signal, the first additional signal, the second additional signal,.
- the first delay time error signal, the second delay time error signal,... The n th delay time error signal may be generated.
- the first reference signal, the second reference signal In the generating of the opposite noise signal, the first reference signal, the second reference signal,... Analyzing the frequency of the n th reference signal, and analyzing the first reference signal, the second reference signal,. Selects a frequency to be controlled among the frequencies of the n th reference signal to select the first counter noise signal, the second counter noise signal,... And generating the n th counter noise signal.
- the n th additional signal may be a frequency signal other than an audible frequency.
- an additional signal is generated to generate a delay time error signal, and thus, an unstable additional path transfer function in which the speed of the sound is changed by changing the ambient temperature or pressure. Noise can be controlled even in an environment having a.
- the additional path transfer function initial model is updated in real time by the delay time error signal, and generates a second adaptive filter using the reference noise signal and the signal caused by the second noise. Since the third adaptive noise signal is generated by applying the signal to the second adaptive filter, the noise may be controlled in any environment in which the delay time of the additional path transfer function varies linearly with frequency according to temperature or pressure.
- the noise control method since the white noise signal is generated, the sound for the white noise signal is output, and the additional path transfer function initial model is generated.
- the initial model of the additional path transfer function can be easily generated.
- the delay time error signal is generated after high pass filtering the signal caused by the second noise, compared to the additional signal, the audio frequency band included in the signal caused by the second noise is reduced.
- the change in the delay time of the additional path transfer function may be calculated using only the ultrasonic band included in the signal generated by the second noise. Therefore, the calculation of the change in the delay time of the additional path transfer function can be made simpler.
- the frequency of the reference signal is analyzed and the frequency to be controlled is selected from among the frequencies of the analyzed reference signal to generate the opposite noise signal, only desired frequency noise can be reduced.
- the process of calculating the change in delay time using the additional signal can be simplified.
- the noise control method since a frequency signal other than an audible frequency is used as an additional signal, it detects a change in delay time without generating additional noise generated when the signal of the audio frequency is used as an additional signal. You can compensate.
- the first additional signal, the second additional signal,... Generates an nth additional signal to generate a first delay time error signal, a second delay time error signal,.
- the noise can be controlled and the noise can be completely removed even in an environment having an unstable additional path transfer function in which the ambient temperature or pressure changes and the speed of the sound changes.
- the additional path transfer function initial model includes a first delay time error signal, a second delay time error signal,. Since it is updated in real time by the nth delay time error signal, the noise can be controlled in any environment in which the delay time of the additional path transfer function varies linearly with frequency according to temperature or pressure.
- the additional path transfer function initial model since the sound for the white noise signal is generated to generate the additional path transfer function initial model, the additional path transfer function initial model according to the additional path transfer function only by the transmitted signal by the output sound. You can simply create
- the first error signal, the second error signal,... After the high pass filtering the n-th error signal, the first additional signal, the second additional signal,.
- the audio frequency band included in the n-th error signal is filtered to obtain a first error signal, a second error signal,.
- the change in the delay time of the additional path transfer function may be calculated more simply by using only the ultrasonic band included in the n th error signal.
- the first reference signal, the second reference signal,... Analyze the frequency of the n th reference signal, and analyze the first reference signal, the second reference signal,. Selects a frequency to be controlled among the frequencies of the n-th reference signal so that the first opposite noise signal, the second opposite noise signal,... Since the nth counter noise signal is generated, it is possible to reduce only desired frequency noise, and the process of calculating the change in delay time using the nth additional signal can be simplified.
- a frequency signal other than an audible frequency is converted into a first additional signal, a second additional signal,... Since the nth additional signal is used, the audible frequency is used as the first additional signal, the second additional signal,. For example, it is possible to detect a change in delay time without compensating for additional noise generated when using the n th additional signal and simultaneously compensate for this.
- 1 is a schematic diagram of an algorithm for performing a noise control method according to an embodiment.
- FIG. 2 is a schematic diagram illustrating an example of the active noise control algorithm illustrated in FIG. 1.
- FIG. 3 is a first embodiment of the additional path transfer function model shown in FIG. 2.
- FIG. 4 is a second embodiment of the additional path transfer function model shown in FIG. 2.
- FIG. 5 is a schematic diagram of the initial model of the additional path transfer function shown in FIG. 4.
- FIG. 6 is a schematic diagram of an additional path transfer function update algorithm shown in FIG. 4.
- FIG. 7 is a schematic diagram of the delay analyzer shown in FIG. 2.
- FIG. 8 illustrates an example of analyzing a change in delay time in the delay time analyzer illustrated in FIG. 2.
- FIG. 9 is a flowchart illustrating a noise control method according to the embodiment.
- FIG. 10 is a flowchart illustrating a method of generating an additional path transfer function initial model.
- 11 is a flowchart of an algorithm for performing the noise control method according to the embodiment.
- FIG. 1 is a schematic diagram of an algorithm for a noise control method according to an embodiment.
- an algorithm for a noise control method includes an active noise control (ANC) algorithm unit 100 and a secondary path transfer function 200. And a sensing unit 300.
- ANC active noise control
- the active noise control algorithm 100 receives a reference signal 10, an additional signal 20, and an error 60, and outputs an opposite noise signal 30. Can be.
- the active noise control algorithm unit 100 may generate and output the first counter noise signal 30 using the reference signal 10, and the first error signal 60 caused by the first noise may be input.
- the second counter noise signal 30 may be generated and output using the reference signal 10 and the additional signal 20, and the second error signal 60 due to the second noise is input
- the third counter noise signal 30 may be generated and output using the reference signal 10 and the second error signal 60.
- the additional path transfer function unit 200 may receive the first to third counter noise signals 30 and output a sound 40.
- the additional path transfer function 200 may include a sound output means such as a speaker.
- the additional path transfer function unit 200 may output the first sound 40 with respect to the first reverse noise signal 30, and the second reverse noise signal.
- the noise signal 30 is input
- the second sound 40 with respect to the second counter noise signal 30 may be output
- the third counter noise signal is input.
- the third sound 40 for 30 may be output.
- the detector 300 may detect the first and second noises and may output the first error signal 60 and the second error signal 60.
- the sensing unit 300 may include a sensor such as an error microphone.
- the detector 300 may detect the first noise and output the first error signal 60 while the first sound 40 is output, and the second while the second sound 40 is output.
- the second error signal 60 may be output by detecting the noise.
- the reference signal 10 may be obtained by placing a microphone on the noise transmission path, by using an accelerometer that may sense vibration, or by using a signal generator.
- the additional signal 20 is a periodic signal that is repeated at a constant period.
- the additional signal 20 may be generated as a signal other than an audible frequency to calculate a change in delay time.
- the first to third anti-noise signals 30 are signals having an opposite phase (180 degrees) with respect to the signal of the noise 50.
- the first to third counter noise signals 30 may be output values of algorithms automatically calculated for each sample to reduce power of noise.
- the first to third sounds 40 are sounds for the first to third counter noise signals 30.
- the first to third sounds 40 may overlap with the noise 50.
- Noise 50 is generally a sound that causes discomfort.
- the noise 50 may be noise generated by noise sources (engines, compressors, motors, fans, propellers, etc.).
- the first and second error signals 60 are signals generated when the noise 50 is less canceled when the first to third sounds 40 and the noise 50 overlap each other.
- the first and second error signals 60 are generated when the sensing unit 300 detects the first to third sounds 40.
- the first microphone detects the first to nth reference noises, and the detector 300 detects the first to nth noises. can do.
- the first microphone may be a microphone placed on the noise transmission path described above, and the detector 300 may include an error microphone.
- the error microphone may be a second microphone.
- the detector 300 detects the first noise
- the first microphone again detects the second reference noise
- the detector 300 detects the second reference noise.
- the first microphone may detect the n-th reference noise
- the detector 300 may detect the n-th noise. In this case, the above-described process may be repeated until the detector 300 does not detect the earliest order of the second to n-th noise.
- the active noise control algorithm unit 100 includes the first to n th reference signals 10 caused by the first to n th reference noises, the first to n th error signals 60 caused by the first to n th noises, and the first to n th noises.
- the n th to n th additional signals 20 may be input, and the first to n th counter noise signals 30 may be generated and output.
- the active noise control algorithm 100 receives the first reference signal 10, the first additional signal 20, and the first error signal 60, and generates the first counter noise signal 30. After outputting, the second reference signal 10, the second additional signal 20, and the second error signal 60 are input, the second counter noise signal 30 is generated and output, and then the nth reference signal (10), the n th additional signal 20 and the n th error signal 60 may be input, and the n th counter noise signal 30 may be generated and output.
- the additional path transfer function unit 200 may receive the first to n-th counter noise signals 30 and output the first to n-th sound 40.
- the additional path transfer function unit 200 outputs the first sound 40 with respect to the first opposite noise signal 30 and the second opposite noise signal.
- the second sound 40 is output to the second counter noise signal 30, and when the n-th counter noise signal 30 is input, the n-th counter noise signal 30 is input.
- the n th sound 40 may be output.
- the detector 300 may detect the first and second noises and may output the first error signal 60 and the second error signal 60.
- the detector 300 may detect the first noise and output the first error signal 60 while the first sound 40 is output, and the second while the second sound 40 is output.
- the second error signal 60 may be output by detecting the noise.
- FIG. 2 is a schematic diagram illustrating an example of an active noise control algorithm shown in FIG. 1. 1 and 2, the active noise control algorithm unit 100 according to the embodiment includes an adaptive filter 110, a group delay analyzer 120, and an additional path transfer function model ( secondary path transfer function model 130 and an update algorithm 140.
- the active noise control algorithm unit 100 includes an adaptive filter 110, a group delay analyzer 120, and an additional path transfer function model ( secondary path transfer function model 130 and an update algorithm 140.
- the adaptive filter 110 may receive the reference signal 10 and output the filtered reference signal.
- the adaptive filter 110 may filter the input reference signal 10 to generate a filtered reference signal and output the generated filtered reference signal.
- the filtered reference signal may be converted into an opposite noise signal 30 through phase inversion.
- the additional signal 20 may be added to the opposite noise signal 30.
- the delay time analyzer 120 may receive the error signal 60 and the additional signal 20, and output a group delay error signal 70.
- the delay time error signal 70 may be a phase error changed by temperature or pressure around the system.
- the delay time analyzer 120 compares the delay time error signal 70 by comparing the additional signal 20 with the error signal 60 to calculate a change in the delay time of the system due to temperature or pressure around the system. And the generated delay time error signal 70 is output.
- the delay time analyzer 120 may generate the delay time error signal 70 by using a method of analyzing a correlation between the additional signal 20 and corresponding frequency components of the error signal 60. Can be.
- analyzing the correlation may be to use a correlation analyzer.
- the additional path transfer function model 130 may receive the delay time error signal 70 and the reference signal 10 and output the reference noise signal 80. Specifically, the additional path transfer function model 130 is updated in real time to compensate for the influence of the additional path transfer function on the algorithm using the delay time error signal 70. In this case, the reference signal 10 may be applied to the updated additional path transfer function model 130 to generate the reference noise signal 80.
- the update algorithm 140 may receive the reference noise signal 80 and the error signal 60, and output the improvement adaptation filter 90.
- the update algorithm 140 may generate the improvement adaptation filter 90 by multiplying the reference noise signal 80 and the error signal 60.
- the reference noise signal 80 and the error signal 60 may be further multiplied by a constant called a step-size.
- the adaptive filter 110 may further receive the improved adaptive filter 90 and output the filtered reference signal.
- the adaptive filter 110 may generate the second adaptive filter 110 by adding the improved adaptive filter 90 and the first adaptive filter 110.
- the first adaptive filter 110 may have a value set in advance, and may be generally set to 0, and the second adaptive filter 110 may have an updated first adaptive filter 110.
- the second adaptive filter 110 may filter the reference signal 10 to generate a filtered reference signal, and output the generated filtered reference signal.
- the additional signal 20 may be a signal other than an audible frequency. Specifically, since the audible frequency is about 20 Hz to 20.000 Hz, the additional signal 20 may be an ultra low frequency of 20 Hz or less or an ultrasonic wave of 20,000 Hz or more. However, due to the limitation of the dynamic characteristics of a typical speaker, sounds below 20Hz may not play well. Therefore, the additional signal 20 may be ultrasonic waves excluding ultra low frequencies.
- the additional signal 20 is generated at an audible frequency and the delay time error signal 70 is calculated using the additional signal 20 and the opposite noise signal 30, the additional signal 20 is generated due to the additional signal 20 of the audio frequency. Additional noise may occur. Moreover, if the frequency is a component included in the frequency band of the noise spectrum, problems may occur in the stability and convergence of the algorithm for performing the noise control method.
- the noise control method according to the embodiment generates the additional signal 20 using a signal other than an audible frequency, and calculates the delay time error signal 70 using the additional signal 20 and the opposite noise signal 30. Therefore, additional noise due to the additional signal 20 is not heard.
- normal noise is generated in the audible frequency band, there is an advantage that a problem does not occur in stability and convergence of the algorithm for performing the noise control method.
- FIG. 3 is a first embodiment of the additional path transfer function model shown in FIG. 2.
- the additional path transfer function model 130 is an initial additional path transfer function initial model 131 and a pure delay filter 132 in the form of a transversal filter in a general active noise control method. ) May be included.
- the additional path transfer function initial model 131 may be generated before leaving the factory or after installing the active noise control system. Specifically, after generating the white noise signal of the audio frequency band, it may be generated by detecting it in the error microphone.
- the additional path transfer function initial model 131 may be represented by a finite length filter that simulates an impulse response of the additional path transfer function.
- the pure delay filter 132 may be updated in real time according to the delay time error signal 70 input from the delay time analyzer 120.
- the broadband noise is controlled can do.
- FIG. 4 is a second embodiment of the additional path transfer function model shown in FIG. 2
- FIG. 5 is a schematic diagram of the initial model of the additional path transfer function shown in FIG. 4
- FIG. 6 is the additional path transfer shown in FIG. 4. Schematic of the function update algorithm.
- the additional path transfer function model 130 may be processed in parallel for each frequency. Specifically, the sine signal and the cosine signal at one frequency are filtered by the additional path transfer function initial model 133 and the additional path transfer function update algorithm 134. The delay time error signal 70 is input to each additional path transfer function update algorithm 134.
- the additional path transfer function initial model 133 may be generated before leaving the factory or after installing the active noise control system. Specifically, after generating a white noise signal of an audible frequency band, it can be generated by detecting with an error microphone.
- the additional path transfer function initial model 133 may classify the additional path transfer function into information of size and phase for each frequency.
- the additional path transfer function initial model 133 may obtain a reference noise signal 80 by multiplying and adding a gain value from the magnitude and phase information of each frequency using the classified sine and cosine signals. .
- Each gain value can be calculated from a previously measured sidepath transfer function, which is fixed.
- the size and phase of each frequency of the initial path transfer function initial model 133 may be calculated and filtered as shown in FIG. 6.
- the system initial delay time can be obtained.
- the delay time error signal 70 which is the difference between the current and initial delay time, is applied to the additional path transfer function update algorithm 134.
- the delay time error signal 70 is multiplied in advance by a gain value of the corresponding frequency, and compensates for the phase of the value.
- f k is the k th frequency
- n is a sample
- ⁇ is the delay time error signal 70 calculated by the delay time analyzer 120.
- the delay time error signal 70 may be multiplied in advance by a gain value of the corresponding frequency, and may be applied in the same manner as the method of the additional path transfer function initial model 133 to compensate for the phase of the value.
- the additional path transfer function update algorithm 134 may predict the time at which the sound arrives from the physical distance because the sound is transmitted in the form of a plane wave in a simple structure such as a duct structure. Similarly, in such a system, if the change in temperature is known, the phase change of the additional path transfer function can be predicted accordingly.
- the delay times for each frequency are the same, and the phase in the frequency domain is linear.
- the additional signal 20 uses a frequency signal other than an audible frequency that is inaudible to humans, so that noise due to addition is not heard but can be measured from the sensor. Therefore, additional noise due to the additional signal 20 does not occur and may not degrade the performance of the original noise control.
- the additional path transfer function model according to the second embodiment may exhibit excellent performance when the noise has a periodic or semi-periodic characteristic.
- FIG. 7 is a schematic diagram of the delay analyzer illustrated in FIG. 2, and FIG. 8 illustrates an example of analyzing a change in delay time in the delay analyzer illustrated in FIG. 2.
- the delay analyzer 120 may include a high pass filter (HPF) (not shown).
- HPF high pass filter
- the error signal 60 may be high pass filtered.
- the error signal 60 transmitted to the delay time analyzer 120 may include an audible frequency band according to noise and an ultrasonic band according to the additional signal 20. Therefore, when the high pass filtering the error signal 60, the audio frequency band of the error signal 60 is filtered, leaving only the ultrasonic band. Therefore, a change in delay time may be calculated using a method of analyzing a correlation between the ultrasonic band of the error signal 60 and the additional signal 20.
- the delay time analyzer 120 includes the high pass filter, calculates the change in the delay time of the additional path transfer function after the high pass filtering of the error signal 60, and thus includes the error signal 60 in the error signal 60.
- the audible frequency band is filtered to calculate a change in delay time of the additional path transfer function using only the ultrasonic band included in the error signal 60. Therefore, there is an advantage that the calculation of the change in delay time of the additional path transfer function can be made simpler.
- the delay time analyzer 120 analyzes corresponding frequency components of the additional signal 20 and the error signal 60, and measures the phase difference between the additional signal 20 and the error signal 60 to detect the delay time error signal ( 70) can be calculated. Therefore, the process of calculating the delay time error signal 70 using the additional signal 20 can be simplified.
- FIG. 9 is a flowchart illustrating a noise control method according to the embodiment.
- the noise control method includes a first output step S10, a first detection step S20, a second output step S30, and a second detection step S40. ) And a third output step S50.
- the first output step S10 receives the reference signal 10, generates a first reverse noise signal 30, and outputs a first sound 40.
- the reference signal 10 is input, the first adaptive filter 110 is generated using the additional path transfer function model 130, and the reference signal 10 is applied to the first adaptive filter 110.
- the first counter noise signal 30 may be generated, and the first sound 40 with respect to the first counter noise signal 30 may be output using sound output means such as a speaker.
- the first sensing step S20 detects the first noise while the first sound 40 is output. Specifically, when noise is less canceled by the overlap of the first sound 40 and the noise 50, the first noise may be detected by the error microphone.
- the second output step S30 When the first noise is detected, the second output step S30 generates a second counter noise signal 30 and outputs a second sound 40. Specifically, when the error microphone detects the first noise, the additional signal 20 is generated to calculate the change in delay time, and the additional signal 20 is added to the first counter noise signal 30 to counter the second noise. The noise signal 30 may be generated and the second counter noise signal 30 may be output.
- the additional signal 20 may be a signal other than an audible frequency.
- the second sensing step S40 detects the second noise while the second sound 40 is output. Specifically, if the noise 50 is less canceled by the overlap of the second sound 40 and the noise 50, the second noise may be detected by the error microphone.
- the third output step S50 When the second noise is sensed, the third output step S50 generates a delay time error signal 70 and outputs a third sound 40. Specifically, when the error microphone detects the second noise, the delay time analyzer 120 generates a delay time error signal 70 by comparing the additional signal 20 and the signal 60 due to the second noise, The additional path transfer function initial models 131 and 133 are updated in real time by the delay time error signal 70, and the reference signal 10 is added to the additional path transfer function model 130 updated by the delay time error signal 70.
- the generation of the delay time error signal 70 in the third output step includes high pass filtering the signal 60 due to the second noise, and then compares the delay time error signal 70 with the additional signal 20. It may be to produce.
- generating the first counter noise signal 30 in the first output stage analyzes the frequency of the reference signal 10, selects a frequency to be controlled among the frequencies of the analyzed reference signal 10, and then selects the first counter noise.
- the noise signal 30 may be generated.
- the noise control method generates the delay time error signal 70 by generating the additional signal 20 when the first noise is detected.
- the noise can be controlled even in an environment having an unstable additional path transfer function that is changed.
- the additional path transfer function initial models 131 and 133 are updated in real time by the delay time error signal 70, and the reference noise signal 80 and the signal caused by the second noise ( Since the second adaptive filter 110 is generated using the reference numeral 60 and the reference signal 10 is applied to the second adaptive filter 110 to generate the third counter noise signal 30, the second adaptive filter 110 is generated according to the temperature or the pressure.
- the noise can be controlled in any environment where the delay time of the additional path transfer function varies linearly with frequency.
- the noise control method generates a delay time error signal 70 in comparison with the additional signal 20 after high pass filtering the signal 60 caused by the second noise.
- the audible frequency band included in the signal 60 may be filtered to calculate a change in delay time of the additional path transfer function using only the ultrasonic band included in the signal 60 due to the second noise. Therefore, there is an advantage that the calculation of the change in delay time of the additional path transfer function can be made simpler.
- the noise control method according to the embodiment analyzes the frequency of the reference signal 10 and selects a frequency to be controlled among the frequencies of the analyzed reference signal 10 to generate the opposite noise signal 30, It is possible to reduce only the frequency noise, and there is an advantage that the process of calculating the change in delay time using the additional signal 20 can be simplified.
- the noise control method according to the embodiment uses a frequency signal other than the audible frequency as the additional signal 20, the delay time is not generated without generating additional noise generated when the signal of the audio frequency is used as the additional signal 20. There is an advantage in that it can detect and compensate for changes.
- FIG. 10 is a flowchart illustrating a method of generating an additional path transfer function initial model.
- the additional path transfer function initial models 131 and 133 may be generated off-line before the active noise control is activated.
- the method of generating the additional path transfer function initial models 131 and 133 before the first output step first generates a white noise signal and outputs a fourth sound ( S101). Specifically, a white noise signal of an audible frequency band may be generated, and a fourth sound of the generated white noise signal may be output.
- the fifth sound is sensed and the additional path transfer function initial models 131 and 133 are generated (S102). Specifically, the additional path transfer function initial models 131 and 133 are generated by using the white noise signal and the transmission signal of the fifth sound detected by the error microphone while the fourth sound is output.
- the noise control method since the white noise signal is generated, the sound for the white noise signal is output, and the additional path transfer function initial models 131 and 133 are generated.
- the initial signal of the additional path transfer function according to the additional path transfer function may be generated more simply by using the transmitted signal alone.
- the additional path transfer function initial models 131 and 133 may also be generated by a Least Mean Square (LMS) method.
- LMS Least Mean Square
- 11 is a flowchart of an algorithm for performing the noise control method according to the embodiment.
- the noise control method may include a sensing step, an additional signal generation step, a counter-noise signal generation step and an output step.
- the sensing step the first microphone detects the first reference noise for the first sample, and the second microphone detects the first noise.
- the first microphone may be a microphone for detecting the noise 50, and the second microphone may be the above-described error microphone.
- the additional signal generating step is performed when the first reference signal 10 by the first reference noise detected by the first microphone and the first error signal 60 by the first noise detected by the second microphone are transmitted.
- the additional signal 20 is generated.
- the first additional signal 20 may be generated by a signal generator or the like.
- the first additional signal 20 may be a signal other than an audible frequency.
- the first opposite noise signal 30 is generated using the first reference signal 10, the first error signal 60, and the first additional signal 20.
- the delay time error signal in which the delay time analyzer 120 generates the first delay time error signal 70 by comparing the first additional signal 20 and the first error signal 60.
- the additional path transfer function model 130 updates the additional path transfer function initial models 131 and 133 in real time using the first delay time error signal 70 to update the additional path transfer function model 130.
- the delay time error signal generating step may generate a first delay time error signal 70 by high pass filtering the first error signal 60 and then comparing it with the first additional signal 20.
- the counter noise generating step may be generated by analyzing a frequency of the first reference signal 10 and selecting a frequency to be controlled among the frequencies of the analyzed first reference signal 10.
- the output stage outputs the first sound 40 to the first counter noise signal 30.
- the first microphone detects the second reference noise for the second sample, and the second microphone detects the second noise.
- the additional signal generating step may include: when the second reference signal 10 by the second reference noise detected by the first microphone and the second error signal 60 by the second noise detected by the second microphone are transmitted, the second additional signal is added. Generate signal 20.
- the second opposite noise signal 30 is generated using the second reference signal 10, the second error signal 60, and the second additional signal 20.
- the delay time error signal in which the delay time analyzer 120 generates the second delay time error signal 70 by comparing the second additional signal 20 and the second error signal 60.
- the additional path transfer function model 130 updates the additional path transfer function initial models 131 and 133 in real time using the second delay time error signal 70 to generate an updated additional path transfer function model.
- the reference noise signal generating step of generating the second reference noise signal 80 by applying the second reference signal 10 to the updated additional path transfer function model 130, and the second error signal 60 and the convergent element The second improved adaptive filter 90 is generated by multiplying with the second reference noise signal 80, and the third adaptive filter 110 is generated by adding the second improved adaptive filter 90 and the second adaptive filter 110.
- the second additional signal In addition to the 20 second opposed it contains a reference signal applied to produce a noise signal (30).
- the output step outputs a second sound 40 for the second counter noise signal 30.
- the first microphone detects the n th reference noise for the n th sample, and the second microphone detects the n th noise.
- the additional signal generating step is performed when the n th reference signal 10 due to the n th reference noise detected by the first microphone and the n th error signal 60 due to the n th noise detected by the second microphone are transmitted.
- the additional signal 20 is generated.
- an nth opposite noise signal 30 is generated using the nth reference signal 10, the nth error signal 60, and the nth additional signal 20.
- the delay time error signal in which the delay time analyzer 120 generates the nth delay time error signal 70 by comparing the n th additional signal 20 and the n th error signal 60.
- the additional path transfer function model 130 updates the additional path transfer function initial models 131 and 133 in real time using the nth delay time error signal 70 to generate an updated additional path transfer function model.
- the reference noise signal generating step of generating the n-th reference noise signal 80 by applying the n-th reference signal 10 to the updated additional path transfer function model 130, and the n-th error signal 60 and the converging element The nth improvement adaptation filter 90 is generated by multiplying with the nth reference noise signal 80, and the n + 1th adaptation filter 110 is added by adding the nth improvement adaptation filter 90 and the nth adaptation filter 110. Applying the generated adaptive filter generation step and the nth reference signal 10 to the n + 1th adaptive filter 110, the nth addition And applying the reference signal to generate the nth counter noise signal 30 by adding the signal 20.
- the output stage outputs an n th sound 40 to the n th opposite noise signal 30.
- the n th reference signal 10 by the n th reference noise detected by the first microphone is filtered by the updated additional path transfer function model 130 to generate the n th reference noise signal 80, and the n th reference noise.
- the noise signal 80 is sequentially stored in a buffer having a length L of the n + 1th adaptive filter 110 (thus, a vector of L length can be obtained for each sample). It is multiplied by the n-th error signal 60 caused by the n-th noise detected by the second microphone. In this case, the result of the multiplication is multiplied by a constant called a step-size, and the coefficient of the nth adaptive filter 110 used in the previous sample (the value of the coefficient is L because it is an L length vector) is added to the current sample. The coefficient of the adaptive filter 110 to be used is obtained. Accordingly, the n th reference signal 10 is filtered by the n + 1 th adaptive filter 110.
- the generation of the n + 1th adaptive filter 110 may include the second error signal 60,.
- the n th error signal 60 may be generated in a direction in which the square value of the n th error signal 60 is minimized.
- the method may further include generating an additional path transfer function initial model by using the transfer signal and the white noise signal detected by the sound.
- the first additional signal 20, the second additional signal 20,... To generate the n-th additional signal 20 to generate the first delay time error signal 70, the second delay time error signal 70,. Since the nth delay time error signal 70 is generated, the noise can be controlled even in an environment having an unstable additional path transfer function in which the ambient temperature or pressure changes and the speed of the sound changes, thereby completely eliminating the noise. There is an advantage to that.
- the additional path transfer function initial models 131 and 133 may include the first delay time error signal 70, the second delay time error signal 70,. Since it is updated in real time by the nth delay time error signal 70, there is an advantage that the noise can be controlled in any environment where the delay time of the additional path transfer function varies linearly with frequency according to temperature or pressure.
- the additional path transfer function initial models 131 and 133 described with reference to FIG. 11 are generated by the same method as described with reference to FIG.
- the additional path transfer function initial models 131 and 133 according to the function can be easily generated.
- there is an advantage that the change in the delay time of the additional path transfer function can be calculated more simply with only the ultrasonic band included in the n-th error signal 60.
- the first reference signal 10, the second reference signal 10,... The frequency of the n th reference signal 10 is analyzed, and the analyzed first reference signal 10, the second reference signal 10,.
- the nth counter noise signal 30 By selecting a frequency to be controlled among the frequencies of the n th reference signal 10, the first reverse noise signal 30, the second reverse noise signal 30,... Since the nth counter noise signal 30 is generated, it is possible to reduce only desired frequency noise, and the process of calculating a change in delay time using the nth additional signal 20 can be simplified. .
- the noise control method according to the embodiment can effectively control the noise even in an environment where the ambient temperature or pressure can be greatly changed.
- the algorithm will be applied as it is, and if the change is large, the phase error will be compensated accordingly and the noise will be stably reduced.
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Abstract
A noise control method according to an embodiment comprises: a first output step for receiving an input of a reference signal to generate a first reverse noise signal, and outputting a first sound for the first reverse noise signal; a first detection step for detecting a first noise while the first sound is being output; a second output step for adding an additional signal to the first reverse noise signal to generate a second reverse noise signal, and outputting a second sound for the second reverse noise signal, when the first noise is detected; a second detection step for detecting a second noise while the second sound is being output; and a third output step for comparing the additional signal with a signal by the second noise to generate a delay time error signal, generating a third reverse noise signal, using the delay time error signal, and outputting a third sound for the third reverse noise signal, when the second noise is detected.
Description
본 발명은 소음제어방법에 관한 것이다.The present invention relates to a noise control method.
일반적으로 소음을 저감하는 방법에는 소음원 제어(noise source control), 수동 소음제어, 능동 소음제어(Active Noise Control, ANC) 등이 있었다.Generally, noise reduction methods include noise source control, passive noise control, and active noise control (ANC).
소음원 제어 방법은 소음의 원인이 되는 제1의 음원인 소음원을 제거하거나 소음이 저감되도록 처리하는 방법이다. 예를 들어, 소음원 제어 방법은 소음을 발생하는 원인이 되는 진동원이 있다면, 이를 제거할 수 있다면 제거하고, 제거할 수 없다면 최대한 진동을 저감하도록 재설계하거나 절연장치를 설치하는 것이다.The noise source control method is a method of removing the noise source, which is the first sound source that causes the noise, or processing the noise to be reduced. For example, the noise source control method is to remove any vibration source that causes noise, if it can be removed, and redesign or install an insulation device to reduce the vibration as much as possible.
수동 소음제어 방법은 소음원으로부터 소음이 전달되는 경로에 흡음재 혹은 차음재 등을 두어, 소음을 저감하는 방법이다. 예를 들어, 수동 소음제어 방법은 도로소음을 차단하고자 방음벽을 설치하는 것이다.The passive noise control method is a method of reducing noise by placing a sound absorbing material or a sound insulating material in a path through which noise is transmitted from a noise source. For example, a passive noise control method is to install a sound barrier to block road noise.
능동 소음제어 방법은 제2의 음원(control source) 혹은 음원들을 이용하여 원하는 목표영역(혹은 목표점)에서의 소음을 저감하는 방법이다. 예를 들어, 능동 소음제어 방법은 마이크로폰에서 측정된 소음을 감지하고, 반대소음신호를 스피커를 통해 출력하여 소음을 제어하는 것이다. 이러한, 능동 소음제어 방법에는 개루프제어, FXLMS(Filtered-X Least Mean Square), FXNLMS(Filtered-X Normalized Least Mean Square), FULMS(Filtered-U recursive Least Mean Square) 알고리즘을 이용하는 능동 소음제어 방법, 다중 주파수를 이용하는 능동 소음제어 방법 등이 있었다.The active noise control method is a method of reducing noise in a desired target area (or target point) by using a second control source or sound sources. For example, the active noise control method is to sense the noise measured by the microphone, and to control the noise by outputting the opposite noise signal through the speaker. Such active noise control methods include an open-loop control, an active noise control method using an FXLMS (Filtered-X Least Mean Square), an FXNLMS (Filtered-X Normalized Least Mean Square), and a FULMS (Filtered-U Recursive Least Mean Square) algorithm. There are active noise control methods using multiple frequencies.
여기서, 개루프제어는 시스템이 매우 안정적인 경우에는 효과적이지만, 대다수의 시스템에는 불확실성(uncertainty)이 존재하여 반복성이 떨어지며 그에 따라 소음 저감성능이 떨어질 수 있다. Here, the open-loop control is effective when the system is very stable, but the majority of the system has an uncertainty (uncertainty), the repeatability is poor and thus the noise reduction performance may be reduced.
시스템 주변의 온도나 압력 등이 크게 변하는 환경에서는 소리의 속도가 바뀌게 된다. 이는 시스템의 지연시간이 바뀌는 것으로, 이러한 환경에서 종래의 능동 소음제어 방법은 소음신호와 반대소음신호 사이에 오차가 발생하여 소음을 저감시키지 못하는 문제가 있었다. In environments where the temperature or pressure around the system changes drastically, the speed of sound changes. This is because the delay time of the system is changed, and in this environment, the conventional active noise control method has a problem in that an error occurs between the noise signal and the opposite noise signal and thus the noise cannot be reduced.
또한, 종래의 능동 소음제어 방법은 마이크로폰에서 측정된 오차신호를 이용하여 부가경로 전달함수 모델을 LMS(Least Mean Square) 방법 등으로 업데이트하였다. In addition, in the conventional active noise control method, the additional path transfer function model is updated by a LMS method using an error signal measured by a microphone.
구체적으로, 종래의 능동 소음제어 방법은 제1 마이크로폰에서 소음신호를 감지하고, 제2 마이크로폰에서 오차신호를 감지하고, 감지된 소음신호에 의한 참조신호가 부가경로 전달함수 초기모델에 필터링되어 참조소음신호가 생성되고, 이 참조소음신호에 오차신호 및 수렴요소를 곱하여 개선적응필터를 생성하고, 개선적응필터와 적응필터를 더하여 새로운 적응필터를 생성하고, 소음신호가 새로운 적응필터에 필터링되어 반대소음신호를 생성하였다.Specifically, in the conventional active noise control method, a noise signal is detected by the first microphone, an error signal is detected by the second microphone, and the reference signal by the detected noise signal is filtered by the additional path transfer function initial model so as to generate a reference noise. A signal is generated, and the reference noise signal is multiplied by an error signal and a convergence element to generate an improved adaptive filter, a new adaptive filter is generated by adding the improved adaptive filter and the adaptive filter, and the noise signal is filtered by the new adaptive filter to produce the opposite noise. Generated signal.
하지만, 시스템 주변의 온도나 압력이 크게 변하는 환경에서 시스템의 지연시간이 바뀌면, 시스템 내의 불확실성으로 인해 부가경로 전달함수가 변하게 되어 부가경로 전달함수 모델과 실제 전달함수 사이에 오차가 발생하게 된다. 이때, 시스템이 가지고 있는 안정성의 조건(stability condition) 내에서 부가경로 전달함수가 변하게 되면, 시스템은 안정적으로 소음을 저감할 수 있지만, 시스템이 가지고 있는 안정성의 조건 밖에서 부가경로 전달함수가 변하게 되면, 소음제어의 안정성 및 수렴성을 저하시키며, 나아가 시스템이 발산할 수 있는 문제를 야기할 수 있다.However, if the delay time of the system is changed in the environment where the temperature or pressure around the system changes drastically, the additional path transfer function is changed due to the uncertainty in the system, causing an error between the additional path transfer function model and the actual transfer function. At this time, if the additional path transfer function is changed within the stability condition of the system, the system can stably reduce noise, but if the additional path transfer function is changed outside the stability condition of the system, It lowers the stability and convergence of the noise control, and may also cause problems that the system may diverge.
[선행기술문헌][Preceding technical literature]
(비특허문헌 1) SEN M. KUO AND DENNIS R. MORGAN, “Active Noise Control: A Tutorial Review” PROCEEDINGS OF THE IEEE, VOL. 87, NO, 6, JUNE 1999(Non-Patent Document 1) SEN M. KUO AND DENNIS R. MORGAN, “Active Noise Control: A Tutorial Review” PROCEEDINGS OF THE IEEE, VOL. 87, NO, 6, JUNE 1999
실시 형태는 주변의 온도나 압력 등이 변하는 환경에서 시스템의 지연시간을 계산하고, 소음신호와 반대소음신호 사이에 오차를 보상하여 소음을 제어할 수 있는 소음제어방법을 제공하는 것을 목적으로 한다.It is an object of the embodiment to provide a noise control method that calculates a delay time of a system in an environment where ambient temperature or pressure changes, and compensates for an error between a noise signal and a counter noise signal to control the noise.
또한, 실시 형태는 주변의 온도나 압력 등이 변하는 환경에서 시스템의 지연시간을 계산하고, 사전에 측정된 부가경로 전달함수 모델과 실제 전달함수 사이의 차이를 보상하여 소음을 제어할 수 있는 소음제어방법을 제공하는 것을 목적으로 한다.In addition, the embodiment is a noise control that calculates the delay time of the system in an environment where the ambient temperature or pressure changes, and controls the noise by compensating the difference between the previously measured additional path transfer function model and the actual transfer function. It is an object to provide a method.
실시 형태에 따른 소음제어방법은, 참조신호를 입력받아 제1 반대소음신호를 생성하고, 상기 제1 반대소음신호에 대한 제1 음향을 출력하는 제1 출력단계; 상기 제1 음향이 출력되는 동안 제1 소음을 감지하는 제1 감지단계; 상기 제1 소음이 감지되는 경우, 상기 제1 반대소음신호에 부가신호를 더하여 제2 반대소음신호를 생성하고, 상기 제2 반대소음신호에 대한 제2 음향을 출력하는 제2 출력단계; 상기 제2 음향이 출력되는 동안 제2 소음을 감지하는 제2 감지단계; 및 상기 제2 소음이 감지되는 경우, 상기 부가신호와 상기 제2 소음에 의한 신호를 비교하여 지연시간 오차신호를 생성하고, 상기 지연시간 오차신호를 이용하여 제3 반대소음신호를 생성하고, 상기 제3 반대소음신호에 대한 제3 음향을 출력하는 제3 출력단계;를 포함한다.A noise control method according to an embodiment includes: a first output step of receiving a reference signal, generating a first counter noise signal, and outputting a first sound with respect to the first counter noise signal; A first sensing step of sensing a first noise while the first sound is output; A second output step of generating a second counter noise signal by adding an additional signal to the first counter noise signal when the first noise is detected, and outputting a second sound with respect to the second counter noise signal; A second sensing step of sensing a second noise while the second sound is output; And when the second noise is detected, comparing the additional signal with a signal caused by the second noise to generate a delay time error signal, and generating a third counter noise signal using the delay time error signal. And a third output step of outputting a third sound with respect to the third counter noise signal.
여기서, 상기 제1 출력단계는, 상기 참조신호를 제1 적응필터에 적용하여 상기 제1 반대소음신호를 생성하고, 상기 제3 출력단계는, 상기 지연시간 오차신호에 의해 업데이트된 부가경로 전달함수 모델에 상기 참조신호를 적용하여 참조소음신호를 생성하고, 상기 참조소음신호와 상기 제2 소음에 의한 신호를 곱하여 생성된 개선적응필터와 상기 제1 적응필터를 더하여 제2 적응필터를 생성하고, 상기 참조신호를 상기 제2 적응필터에 적용하여 상기 제3 반대소음신호를 생성할 수 있다.Here, in the first output step, the reference signal is applied to the first adaptive filter to generate the first counter noise signal, and the third output step is an additional path transfer function updated by the delay time error signal. Generating a reference noise signal by applying the reference signal to a model, generating a second adaptive filter by adding the first adaptive filter and the improved adaptive filter generated by multiplying the reference noise signal by the second noise signal, The third opposite noise signal may be generated by applying the reference signal to the second adaptive filter.
여기서, 상기 제1 출력단계 이전에, 백색잡음신호를 생성하고, 상기 백색잡음신호에 대한 제4 음향을 출력하는 단계; 및 상기 제4 음향이 출력되는 동안 감지된 제5 음향에 의한 전달신호와 상기 백색잡음신호를 이용하여 상기 부가경로 전달함수의 초기모델을 생성하는 단계;를 더 포함할 수 있다.Here, before the first output step, generating a white noise signal, and outputting a fourth sound for the white noise signal; And generating an initial model of the additional path transfer function using the white noise signal and the transmission signal of the fifth sound detected while the fourth sound is output.
여기서, 상기 제3 출력단계는, 상기 제2 소음에 의한 신호를 하이패스 필터링한 후, 상기 부가신호와 비교하여 상기 지연시간 오차신호를 생성할 수 있다.Here, in the third output step, after the high pass filtering the signal caused by the second noise, the delay time error signal can be generated by comparing with the additional signal.
여기서, 상기 제1 출력단계는, 상기 참조신호의 주파수를 분석하고, 상기 참조신호의 주파수 중 제어하고자 하는 주파수를 선택하여 상기 제1 반대소음신호를 생성할 수 있다.Here, in the first output step, the frequency of the reference signal may be analyzed, and the first counter noise signal may be generated by selecting a frequency to be controlled among the frequencies of the reference signal.
여기서, 상기 부가신호는 가청주파수 외의 주파수 신호일 수 있다.Here, the additional signal may be a frequency signal other than the audible frequency.
또한, 실시 형태에 따른 소음제어방법은, 제1 마이크로폰이 제1 샘플, 제2 샘플, …, 제n 샘플에 대한 제1 참조소음, 제2 참조소음, …, 제n 참조소음을 감지하고, 제2 마이크로폰이 제1 소음, 제2 소음, …, 제n 소음을 감지하는 감지단계; 상기 제1 마이크로폰에서 감지된 상기 제1 참조소음, 상기 제2 참조소음, …, 상기 제n 참조소음에 의한 제1 참조신호, 제2 참조신호, …, 제n 참조신호와 상기 제2 마이크로폰에서 감지된 상기 제1 소음, 상기 제2 소음, …, 상기 제n 소음에 의한 제1 오차신호, 제2 오차신호, …, 제n 오차신호가 전송되는 경우, 제1 부가신호, 제2 부가신호, …, 제n 부가신호를 생성하는 부가신호 생성단계; 상기 제1 참조신호, 상기 제2 참조신호, …, 상기 제n 참조신호, 상기 제1 오차신호, 상기 제2 오차신호, …, 상기 제n 오차신호 및 상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호를 이용하여 제1 반대소음신호, 제2 반대소음신호, …, 제n 반대소음신호를 생성하는 반대소음신호 생성단계; 및 상기 제1 반대소음신호, 상기 제2 반대소음신호, …, 상기 제n 반대소음신호와 상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호를 더하여 상기 제1 반대소음신호에 대한 제1 음향, 상기 제2 반대소음신호에 대한 제2 음향, …, 상기 제n 반대소음신호에 대한 제n 음향을 출력하는 출력단계;로 이루어진다.In addition, in the noise control method according to the embodiment, the first microphone includes a first sample, a second sample,... , First reference noise for the n th sample, second reference noise,... , N-th reference noise, and the second microphone detects the first noise, the second noise,... A sensing step of detecting an n-th noise; The first reference noise sensed by the first microphone, the second reference noise,... , A first reference signal, a second reference signal by the nth reference noise,... , The first noise detected by the n-th reference signal and the second microphone, the second noise,... , The first error signal, the second error signal due to the n-th noise,... , When the nth error signal is transmitted, the first additional signal, the second additional signal,. An additional signal generating step of generating an nth additional signal; The first reference signal, the second reference signal,... The n th reference signal, the first error signal, the second error signal,... , The nth error signal, the first additional signal, the second additional signal,... A first opposite noise signal, a second opposite noise signal,... A counter noise signal generating step of generating an n-th counter noise signal; And the first counter noise signal, the second counter noise signal,... The nth reverse noise signal, the first additional signal, the second additional signal,... , The first sound of the first counter noise signal, the second sound of the second counter noise signal by adding the n-th additional signal; And an output step of outputting an n th sound with respect to the n th counter noise signal.
여기서, 상기 반대소음신호 생성단계는, 상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호와 상기 제1 오차신호, 상기 제2 오차신호, …, 상기 제n 오차신호를 비교하여 제1 지연시간 오차신호, 제2 지연시간 오차신호, …, 제n 지연시간 오차신호를 생성하는 지연시간 오차신호 생성단계; 상기 제1 지연시간 오차신호, 상기 제2 지연시간 오차신호, …, 상기 제n 지연시간 오차신호를 이용하여 부가경로 전달함수 모델의 부가경로 전달함수 초기모델을 실시간으로 업데이트하여 업데이트된 부가경로 전달함수 모델을 생성하고, 상기 제1 참조신호, 상기 제2 참조신호, …, 상기 제n 참조신호를 상기 업데이트된 부가경로 전달함수 모델에 적용하여 제1 참조소음신호, 제2 참조소음신호, …, 제n 참조소음신호를 생성하는 참조소음신호 생성단계; 상기 제1 오차신호, 상기 제2 오차신호, …, 상기 제n 오차신호를 상기 제1 참조소음신호, 상기 제2 참조소음신호, …, 상기 제n 참조소음신호와 곱하여 제1 개선적응필터, 제2 개선적응필터, …, 제n 개선적응필터를 생성하고, 상기 제1 개선적응필터, 상기 제2 개선적응필터, …, 상기 제n 개선적응필터와 제1 적응필터, 제2 적응필터, …, 제n 적응필터를 더하여 제2 적응필터, 제3 적응필터, …, 제n+1 적응필터를 생성하는 적응필터 생성단계; 및 상기 제1 참조신호, 상기 제2 참조신호, …, 상기 제n 참조신호를 상기 제2 적응필터, 상기 제3 적응필터, …, 상기 제n+1 적응필터에 적용한 후, 제1 부가신호, 제2 부가신호, …, 제n 부가신호를 더하여 상기 제1 반대소음신호, 상기 제2 반대소음신호, …, 상기 제n 반대소음신호를 생성하는 참조신호 적용단계;를 포함하고, 상기 적응필터 생성단계는, 상기 제2 오차신호, …, 상기 제n 오차신호의 제곱 값이 최소화되는 방향으로 상기 제2 적응필터, 상기 제3 적응필터, …, 상기 제n+1 적응필터를 생성할 수 있다.Here, in the generating of the opposite noise signal, the first additional signal, the second additional signal,... The nth additional signal, the first error signal, the second error signal,... Comparing the n-th error signal to obtain a first delay time error signal, a second delay time error signal,. A delay time error signal generating step of generating an nth delay time error signal; The first delay time error signal, the second delay time error signal,... Generating an updated additional path transfer function model by updating an initial model of the additional path transfer function of the additional path transfer function model in real time using the n th delay time error signal, and generating the first reference signal and the second reference signal ,… Applying the n th reference signal to the updated additional path transfer function model to generate a first reference noise signal, a second reference noise signal,... A reference noise signal generating step of generating an n-th reference noise signal; The first error signal, the second error signal,... The n th error signal may be converted into the first reference noise signal, the second reference noise signal,. A first improvement adaptation filter, a second improvement adaptation filter,. Generate an nth improvement adaptation filter, the first improvement adaptation filter, the second improvement adaptation filter,. , The nth improvement adaptive filter, the first adaptive filter, the second adaptive filter,. The second adaptive filter, the third adaptive filter,. An adaptive filter generating step of generating an n + 1th adaptive filter; And the first reference signal, the second reference signal,... The n th reference signal is applied to the second adaptive filter, the third adaptive filter,. , After applying to the n + 1th adaptive filter, a first additional signal, a second additional signal,. , By adding the n-th additional signal, the first opposite noise signal, the second opposite noise signal,... And a reference signal applying step of generating the nth counter noise signal. The adaptive filter generating step includes: the second error signal; , The second adaptive filter, the third adaptive filter,... In a direction in which the square of the n-th error signal is minimized. The n + 1th adaptive filter may be generated.
여기서, 감지 단계 이전에, 백색잡음신호를 생성하고, 상기 백색잡음신호에 대한 음향을 출력하는 단계; 및 상기 제2 마이크로폰에서 감지된 상기 음향에 의한 전달신호와 상기 백색잡음신호를 이용하여 상기 부가경로 전달함수 초기모델을 생성하는 단계;를 더 포함할 수 있다.Here, before the sensing step, generating a white noise signal, and outputting a sound for the white noise signal; And generating the additional path transfer function initial model using the transfer signal of the sound and the white noise signal detected by the second microphone.
여기서, 상기 지연시간 오차신호 생성단계는, 상기 제1 오차신호, 상기 제2 오차신호, …, 상기 제n 오차신호를 하이패스 필터링한 후, 상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호와 비교하여 상기 제1 지연시간 오차신호, 상기 제2 지연시간 오차신호, …, 상기 제n 지연시간 오차신호를 생성할 수 있다.The delay time error signal generating step may include the first error signal, the second error signal,... After the high pass filtering the n-th error signal, the first additional signal, the second additional signal,. The first delay time error signal, the second delay time error signal,... The n th delay time error signal may be generated.
여기서, 상기 반대소음신호 생성단계는, 상기 제1 참조신호, 상기 제2 참조신호, …, 상기 제n 참조신호의 주파수를 분석하고, 상기 분석된 제1 참조신호, 제2 참조신호, …, 제n 참조신호의 주파수 중 제어하고자 하는 주파수를 선택하여 상기 제1 반대소음신호, 상기 제2 반대소음신호, …, 상기 제n 반대소음신호를 생성하는 단계;를 포함할 수 있다.In the generating of the opposite noise signal, the first reference signal, the second reference signal,... Analyzing the frequency of the n th reference signal, and analyzing the first reference signal, the second reference signal,. Selects a frequency to be controlled among the frequencies of the n th reference signal to select the first counter noise signal, the second counter noise signal,... And generating the n th counter noise signal.
여기서, 상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호는 가청주파수 외의 주파수 신호일 수 있다.Here, the first additional signal, the second additional signal,... The n th additional signal may be a frequency signal other than an audible frequency.
실시 형태에 따른 소음제어방법에 의하면, 제1 소음이 감지되는 경우, 부가신호를 생성하여 지연시간 오차신호를 생성하기 때문에, 주변의 온도나 압력 등이 변하여 소리의 속도가 바뀌는 불안정한 부가경로 전달함수를 가지는 환경에서도 소음을 제어할 수 있다.According to the noise control method according to the embodiment, when the first noise is detected, an additional signal is generated to generate a delay time error signal, and thus, an unstable additional path transfer function in which the speed of the sound is changed by changing the ambient temperature or pressure. Noise can be controlled even in an environment having a.
실시 형태에 따른 소음제어방법에 의하면, 부가경로 전달함수 초기모델이 지연시간 오차신호에 의해 실시간으로 업데이트되고, 참조소음신호와 제2 소음에 의한 신호를 이용하여 제2 적응필터를 생성하고, 참조신호를 제2 적응필터에 적용하여 제3 반대소음신호를 생성하기 때문에, 온도나 압력에 따라 부가경로 전달함수의 지연시간이 주파수 별로 선형적으로 변하는 어떠한 환경에서도 소음을 제어할 수 있다.According to the noise control method according to the embodiment, the additional path transfer function initial model is updated in real time by the delay time error signal, and generates a second adaptive filter using the reference noise signal and the signal caused by the second noise. Since the third adaptive noise signal is generated by applying the signal to the second adaptive filter, the noise may be controlled in any environment in which the delay time of the additional path transfer function varies linearly with frequency according to temperature or pressure.
실시 형태에 따른 소음제어방법에 의하면, 백색잡음신호를 생성하고, 백색잡음신호에 대한 음향을 출력하여 부가경로 전달함수 초기모델을 생성하기 때문에, 출력된 음향에 의한 전달신호만으로도 부가경로 전달함수에 따른 부가경로 전달함수 초기모델을 간단하게 생성할 수 있다.According to the noise control method according to the embodiment, since the white noise signal is generated, the sound for the white noise signal is output, and the additional path transfer function initial model is generated. The initial model of the additional path transfer function can be easily generated.
실시 형태에 따른 소음제어방법에 의하면, 제2 소음에 의한 신호를 하이패스 필터링한 후, 부가신호와 비교하여 지연시간 오차신호를 생성하기 때문에, 제2 소음에 의한 신호에 포함된 가청주파수 대역이 필터링되어 제2 소음에 의한 신호에 포함된 초음파 대역만으로 부가경로 전달함수의 지연시간의 변화를 계산할 수 있다. 따라서, 부가경로 전달함수의 지연시간의 변화의 계산이 보다 더 간단해질 수 있다.According to the noise control method according to the embodiment, since the delay time error signal is generated after high pass filtering the signal caused by the second noise, compared to the additional signal, the audio frequency band included in the signal caused by the second noise is reduced. The change in the delay time of the additional path transfer function may be calculated using only the ultrasonic band included in the signal generated by the second noise. Therefore, the calculation of the change in the delay time of the additional path transfer function can be made simpler.
실시 형태에 따른 소음제어방법에 의하면, 참조신호의 주파수를 분석하고, 분석된 참조신호의 주파수 중 제어하고자 하는 주파수를 선택하여 반대소음신호를 생성하기 때문에, 원하는 주파수 소음만 저감하는 것이 가능하며, 부가신호를 이용하여 지연시간의 변화를 계산하는 과정이 간단해질 수 있다.According to the noise control method according to the embodiment, since the frequency of the reference signal is analyzed and the frequency to be controlled is selected from among the frequencies of the analyzed reference signal to generate the opposite noise signal, only desired frequency noise can be reduced. The process of calculating the change in delay time using the additional signal can be simplified.
실시 형태에 따른 소음제어방법에 의하면, 가청주파수 외의 주파수 신호를 부가신호로 이용하기 때문에, 가청주파수의 신호를 부가신호로 이용할 때 발생하는 추가적인 소음을 발생하지 않고 지연시간의 변화를 감지하면서 동시에 이를 보상할 수 있다.According to the noise control method according to the embodiment, since a frequency signal other than an audible frequency is used as an additional signal, it detects a change in delay time without generating additional noise generated when the signal of the audio frequency is used as an additional signal. You can compensate.
실시 형태에 따른 소음제어방법에 의하면, 제1 부가신호, 제2 부가신호, …, 제n 부가신호를 생성하여 제1 지연시간 오차신호, 제2 지연시간 오차신호, …, 제n 지연시간 오차신호를 생성하기 때문에, 주변의 온도나 압력 등이 변하여 소리의 속도가 바뀌는 불안정한 부가경로 전달함수를 가지는 환경에서도 소음을 제어할 수 있고, 소음을 완전히 제거할 수 있다.According to the noise control method according to the embodiment, the first additional signal, the second additional signal,... Generates an nth additional signal to generate a first delay time error signal, a second delay time error signal,. In addition, since the nth delay time error signal is generated, the noise can be controlled and the noise can be completely removed even in an environment having an unstable additional path transfer function in which the ambient temperature or pressure changes and the speed of the sound changes.
실시 형태에 따른 소음제어방법에 의하면, 부가경로 전달함수 초기모델이 제1 지연시간 오차신호, 제2 지연시간 오차신호, …, 제n 지연시간 오차신호에 의해 실시간으로 업데이트되기 때문에, 온도나 압력에 따라 부가경로 전달함수의 지연시간이 주파수 별로 선형적으로 변하는 어떠한 환경에서도 소음을 제어할 수 있다.According to the noise control method according to the embodiment, the additional path transfer function initial model includes a first delay time error signal, a second delay time error signal,. Since it is updated in real time by the nth delay time error signal, the noise can be controlled in any environment in which the delay time of the additional path transfer function varies linearly with frequency according to temperature or pressure.
실시 형태에 따른 소음제어방법에 의하면, 백색잡음신호에 대한 음향을 출력하여 부가경로 전달함수 초기모델을 생성하기 때문에, 출력된 음향에 의한 전달신호만으로도 부가경로 전달함수에 따른 부가경로 전달함수 초기모델을 간단하게 생성할 수 있다.According to the noise control method according to the embodiment, since the sound for the white noise signal is generated to generate the additional path transfer function initial model, the additional path transfer function initial model according to the additional path transfer function only by the transmitted signal by the output sound. You can simply create
실시 형태에 따른 소음제어방법에 의하면, 제1 오차신호, 제2 오차신호, …, 제n 오차신호를 하이패스 필터링한 후, 제1 부가신호, 제2 부가신호, …, 제n 부가신호와 비교하여 제1 지연시간 오차신호, 제2 지연시간 오차신호, …, 제n 지연시간 오차신호를 생성하기 때문에, 제1 오차신호, 제2 오차신호, …, 제n 오차신호에 포함된 가청주파수 대역이 필터링되어 제1 오차신호, 제2 오차신호, …, 제n 오차신호에 포함된 초음파 대역만으로 보다 더 간단하게 부가경로 전달함수의 지연시간의 변화를 계산할 수 있다.According to the noise control method according to the embodiment, the first error signal, the second error signal,... After the high pass filtering the n-th error signal, the first additional signal, the second additional signal,. A first delay time error signal, a second delay time error signal,... Since the nth delay time error signal is generated, the first error signal, the second error signal,... The audio frequency band included in the n-th error signal is filtered to obtain a first error signal, a second error signal,. In addition, the change in the delay time of the additional path transfer function may be calculated more simply by using only the ultrasonic band included in the n th error signal.
실시 형태에 따른 소음제어방법에 의하면, 제1 참조신호, 제2 참조신호, …, 제n 참조신호의 주파수를 분석하고, 분석된 제1 참조신호, 제2 참조신호, …, 제n 참조신호의 주파수 중 제어하고자 하는 주파수를 선택하여 제1 반대소음신호, 제2 반대소음신호, …, 제n 반대소음신호를 생성하기 때문에, 원하는 주파수 소음만 저감하는 것이 가능하며, 제n 부가신호를 이용하여 지연시간의 변화를 계산하는 과정이 간단해질 수 있다.According to the noise control method according to the embodiment, the first reference signal, the second reference signal,... Analyze the frequency of the n th reference signal, and analyze the first reference signal, the second reference signal,. Selects a frequency to be controlled among the frequencies of the n-th reference signal so that the first opposite noise signal, the second opposite noise signal,... Since the nth counter noise signal is generated, it is possible to reduce only desired frequency noise, and the process of calculating the change in delay time using the nth additional signal can be simplified.
실시 형태에 따른 소음제어방법에 의하면, 가청주파수 외의 주파수 신호를 제1 부가신호, 제2 부가신호, …, 제n 부가신호로 이용하기 때문에, 가청주파수를 제1 부가신호, 제2 부가신호, …, 제n 부가신호로 이용할 때 발생하는 추가적인 소음을 발생하지 않고 지연시간의 변화를 감지하면서 동시에 이를 보상할 수 있다.According to the noise control method according to the embodiment, a frequency signal other than an audible frequency is converted into a first additional signal, a second additional signal,... Since the nth additional signal is used, the audible frequency is used as the first additional signal, the second additional signal,. For example, it is possible to detect a change in delay time without compensating for additional noise generated when using the n th additional signal and simultaneously compensate for this.
도 1은 실시 형태에 따른 소음제어방법을 수행하는 알고리즘의 전체적인 도식도이다.1 is a schematic diagram of an algorithm for performing a noise control method according to an embodiment.
도 2는 도 1에 도시된 능동소음제어 알고리즘의 일 예를 설명하기 위한 도식도이다.FIG. 2 is a schematic diagram illustrating an example of the active noise control algorithm illustrated in FIG. 1.
도 3은 도 2에 도시된 부가경로 전달함수 모델의 제1 실시예다.3 is a first embodiment of the additional path transfer function model shown in FIG. 2.
도 4는 도 2에 도시된 부가경로 전달함수 모델의 제2 실시예다.FIG. 4 is a second embodiment of the additional path transfer function model shown in FIG. 2.
도 5는 도 4에 도시된 부가경로 전달함수 초기모델의 도식도이다.FIG. 5 is a schematic diagram of the initial model of the additional path transfer function shown in FIG. 4.
도 6은 도 4에 도시된 부가경로 전달함수 업데이트 알고리즘의 도식도이다.6 is a schematic diagram of an additional path transfer function update algorithm shown in FIG. 4.
도 7은 도 2에 도시된 지연시간 분석기의 도식도이다.7 is a schematic diagram of the delay analyzer shown in FIG. 2.
도 8은 도 2에 도시된 지연시간 분석기에서 지연시간의 변화를 분석하는 일 예를 도시한다.FIG. 8 illustrates an example of analyzing a change in delay time in the delay time analyzer illustrated in FIG. 2.
도 9는 실시 형태에 따른 소음제어방법을 설명하기 위한 순서도이다.9 is a flowchart illustrating a noise control method according to the embodiment.
도 10은 부가경로 전달함수 초기모델을 생성하는 방법을 설명하기 위한 순서도이다.10 is a flowchart illustrating a method of generating an additional path transfer function initial model.
도 11은 실시 형태에 따른 소음제어방법을 수행하는 알고리즘의 순서도이다.11 is a flowchart of an algorithm for performing the noise control method according to the embodiment.
후술하는 상세한 설명은, 본 발명이 실시될 수 있는 특정 실시 형태를 예시로서 도시하는 첨부 도면을 참조한다. 이들 실시 형태는 당업자가 본 발명을 실시할 수 있기에 충분하도록 상세히 설명된다. 본 발명의 다양한 실시 형태는 서로 다르지만 상호 배타적일 필요는 없음이 이해되어야 한다. 예를 들어, 여기에 기재되어 있는 특정 형상, 구조 및 특성은 일 실시 형태에 관련하여 본 발명의 정신 및 범위를 벗어나지 않으면서 다른 실시 형태로 구현될 수 있다. 또한, 각각의 개시된 실시 형태 내의 개별 구성요소의 위치 또는 배치는 본 발명의 정신 및 범위를 벗어나지 않으면서 변경될 수 있음이 이해되어야 한다. 따라서, 후술하는 상세한 설명은 한정적인 의미로서 취하려는 것이 아니며, 본 발명의 범위는, 적절하게 설명된다면, 그 청구항들이 주장하는 것과 균등한 모든 범위와 더불어 첨부된 청구항에 의해서만 한정된다. 도면에서 유사한 참조부호는 여러 측면에 걸쳐서 동일하거나 유사한 기능을 지칭한다. DETAILED DESCRIPTION The following detailed description refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that the various embodiments of the invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.
<실시 형태><Embodiment>
도 1은 실시 형태에 따른 소음제어방법을 위한 알고리즘의 전체적인 도식도이다.1 is a schematic diagram of an algorithm for a noise control method according to an embodiment.
도 1을 참조하면, 실시 형태에 따른 소음제어방법을 위한 알고리즘은 능동소음제어(Active Noise Control, ANC) 알고리즘부(algorithm)(100), 부가경로 전달함수부(secondary path transfer function)(200) 및 감지부(300)를 포함할 수 있다.Referring to FIG. 1, an algorithm for a noise control method according to an embodiment includes an active noise control (ANC) algorithm unit 100 and a secondary path transfer function 200. And a sensing unit 300.
능동소음제어 알고리즘부(100)는 참조신호(reference signals)(10), 부가신호(additional signal)(20) 및 오차신호(error)(60)를 입력받고, 반대소음신호(30)를 출력할 수 있다.The active noise control algorithm 100 receives a reference signal 10, an additional signal 20, and an error 60, and outputs an opposite noise signal 30. Can be.
구체적으로, 능동소음제어 알고리즘부(100)는 참조신호(10)를 이용하여 제1 반대소음신호(30)를 생성하여 출력할 수 있고, 제1 소음에 의한 제1 오차신호(60)가 입력되는 경우, 참조신호(10)와 부가신호(20)를 이용하여 제2 반대소음신호(30)를 생성하여 출력할 수 있고, 제2 소음에 의한 제2 오차신호(60)가 입력되는 경우, 참조신호(10)와 제2 오차신호(60)를 이용하여 제3 반대소음신호(30)를 생성하여 출력할 수 있다.In detail, the active noise control algorithm unit 100 may generate and output the first counter noise signal 30 using the reference signal 10, and the first error signal 60 caused by the first noise may be input. In this case, when the second counter noise signal 30 may be generated and output using the reference signal 10 and the additional signal 20, and the second error signal 60 due to the second noise is input, The third counter noise signal 30 may be generated and output using the reference signal 10 and the second error signal 60.
부가경로 전달함수부(200)는 제1 내지 제3 반대소음신호(30)를 입력받고, 음향(40)을 출력할 수 있다. 여기서, 부가경로 전달함수부(200)는 스피커와 같은 음향출력수단 등을 포함할 수 있다.The additional path transfer function unit 200 may receive the first to third counter noise signals 30 and output a sound 40. Here, the additional path transfer function 200 may include a sound output means such as a speaker.
구체적으로, 부가경로 전달함수부(200)는 제1 반대소음신호(30)가 입력되는 경우, 제1 반대소음신호(30)에 대한 제1 음향(40)을 출력할 수 있고, 제2 반대소음신호(30)가 입력되는 경우, 제2 반대소음신호(30)에 대한 제2 음향(40)을 출력할 수 있고, 제3 반대소음신호(30)가 입력되는 경우, 제3 반대소음신호(30)에 대한 제3 음향(40)을 출력할 수 있다. Specifically, when the first reverse noise signal 30 is input, the additional path transfer function unit 200 may output the first sound 40 with respect to the first reverse noise signal 30, and the second reverse noise signal. When the noise signal 30 is input, the second sound 40 with respect to the second counter noise signal 30 may be output, and when the third counter noise signal 30 is input, the third counter noise signal is input. The third sound 40 for 30 may be output.
감지부(300)는 제1 및 제2 소음을 감지하고, 제1 오차신호(60) 및 제2 오차신호(60)를 출력할 수 있다. 여기서, 감지부(300)는 오차 마이크로폰 등과 같은 센서(sensor)를 포함할 수 있다.The detector 300 may detect the first and second noises and may output the first error signal 60 and the second error signal 60. Here, the sensing unit 300 may include a sensor such as an error microphone.
구체적으로, 감지부(300)는 제1 음향(40)이 출력되는 동안 제1 소음을 감지하여 제1 오차신호(60)를 출력할 수 있고, 제2 음향(40)이 출력되는 동안 제2 소음을 감지하여 제2 오차신호(60)를 출력할 수 있다. 참조신호(10)는 소음전달경로에 마이크로폰을 두어 얻거나, 진동을 감지할 수 있는 가속도계를 이용하여 얻거나, 신호 생성기(signal generator) 등을 통해 얻을 수 있다.In detail, the detector 300 may detect the first noise and output the first error signal 60 while the first sound 40 is output, and the second while the second sound 40 is output. The second error signal 60 may be output by detecting the noise. The reference signal 10 may be obtained by placing a microphone on the noise transmission path, by using an accelerometer that may sense vibration, or by using a signal generator.
부가신호(20)는 일정한 주기로 반복되는 주기적인 신호이다. 부가신호(20)는 지연시간의 변화를 계산하기 위해 가청주파수 외의 신호로 생성될 수 있다.The additional signal 20 is a periodic signal that is repeated at a constant period. The additional signal 20 may be generated as a signal other than an audible frequency to calculate a change in delay time.
제1 내지 제3 반대소음신호(30)는 소음(noise)(50)의 신호에 대해 반대위상(180도)을 갖는 신호이다. 제1 내지 제3 반대소음신호(30)는 소음의 파워를 줄이기 위해 자동적으로 매 샘플마다 계산된 알고리즘의 출력 값일 수 있다. The first to third anti-noise signals 30 are signals having an opposite phase (180 degrees) with respect to the signal of the noise 50. The first to third counter noise signals 30 may be output values of algorithms automatically calculated for each sample to reduce power of noise.
제1 내지 제3 음향(40)은 제1 내지 제3 반대소음신호(30)에 대한 소리이다. 제1 내지 제3 음향(40)은 소음(50)과 중첩될 수 있다.The first to third sounds 40 are sounds for the first to third counter noise signals 30. The first to third sounds 40 may overlap with the noise 50.
소음(50)은 일반적으로 불쾌함을 느끼게 하는 소리이다. 소음(50)은 소음원(엔진(engines), 압축기(compressors), 모터(motors), 팬(fans), 프로펠러(propellers) 등)에 의해 발생한 소음일 수 있다.Noise 50 is generally a sound that causes discomfort. The noise 50 may be noise generated by noise sources (engines, compressors, motors, fans, propellers, etc.).
제1 및 제2 오차신호(60)는 제1 내지 제3 음향(40)과 소음(50)이 중첩된 경우, 소음(50)이 덜 상쇄되면 생성되는 신호이다. 제1 및 제2 오차신호(60)는 감지부(300)에서 제1 내지 제3 음향(40)을 감지하는 경우 생성된다.The first and second error signals 60 are signals generated when the noise 50 is less canceled when the first to third sounds 40 and the noise 50 overlap each other. The first and second error signals 60 are generated when the sensing unit 300 detects the first to third sounds 40.
또한, 실시 형태에 따른 소음제어방법을 위한 알고리즘의 다른 예를 설명하면, 먼저, 제1 마이크로폰은 제1 내지 제n 참조소음을 감지하고, 감지부(300)는 제1 내지 제n 소음을 감지할 수 있다. 여기서, 제1 마이크로폰은 상술한 소음전달경로에 둔 마이크로폰일 수 있고, 감지부(300)는 오차 마이크로폰을 포함할 수 있다. 이때, 오차 마이크로폰은 제2 마이크로폰일 수 있다.In addition, another example of an algorithm for the noise control method according to the embodiment will be described. First, the first microphone detects the first to nth reference noises, and the detector 300 detects the first to nth noises. can do. Here, the first microphone may be a microphone placed on the noise transmission path described above, and the detector 300 may include an error microphone. In this case, the error microphone may be a second microphone.
구체적으로, 제1 마이크로폰이 제1 참조소음을 감지하고, 감지부(300)가 제1 소음을 감지한 후, 다시 제1 마이크로폰이 제2 참조소음을 감지하고, 감지부(300)가 제2 소음을 감지한 후, 제1 마이크로폰이 제n 참조소음을 감지하고, 감지부(300)가 제n 소음을 감지할 수 있다. 이때, 상술한 과정은 감지부(300)가 제2 내지 제n 소음 중 가장 빠른 차수의 소음을 감지하지 못할 때까지 반복될 수 있다.Specifically, after the first microphone detects the first reference noise, the detector 300 detects the first noise, the first microphone again detects the second reference noise, and the detector 300 detects the second reference noise. After detecting the noise, the first microphone may detect the n-th reference noise, and the detector 300 may detect the n-th noise. In this case, the above-described process may be repeated until the detector 300 does not detect the earliest order of the second to n-th noise.
능동소음제어 알고리즘부(100)는 제1 내지 제n 참조소음에 의한 제1 내지 제n 참조신호(10), 제1 내지 제n 소음에 의한 제1 내지 제n 오차신호(60) 및 제1 내지 제n 부가신호(20)를 입력받고, 제1 내지 제n 반대소음신호(30)를 생성하여 출력할 수 있다. The active noise control algorithm unit 100 includes the first to n th reference signals 10 caused by the first to n th reference noises, the first to n th error signals 60 caused by the first to n th noises, and the first to n th noises. The n th to n th additional signals 20 may be input, and the first to n th counter noise signals 30 may be generated and output.
구체적으로, 능동소음제어 알고리즘부(100)는 제1 참조신호(10), 제1 부가신호(20) 및 제1 오차신호(60)를 입력받고, 제1 반대소음신호(30)를 생성하여 출력한 후, 제2 참조신호(10), 제2 부가신호(20) 및 제2 오차신호(60)를 입력받고, 제2 반대소음신호(30)를 생성하여 출력한 후, 제n 참조신호(10), 제n 부가신호(20) 및 제n 오차신호(60)를 입력받고, 제n 반대소음신호(30)를 생성하여 출력할 수 있다. In detail, the active noise control algorithm 100 receives the first reference signal 10, the first additional signal 20, and the first error signal 60, and generates the first counter noise signal 30. After outputting, the second reference signal 10, the second additional signal 20, and the second error signal 60 are input, the second counter noise signal 30 is generated and output, and then the nth reference signal (10), the n th additional signal 20 and the n th error signal 60 may be input, and the n th counter noise signal 30 may be generated and output.
부가경로 전달함수부(200)는 제1 내지 제n 반대소음신호(30)를 입력받고, 제1 내지 제n 음향(40)을 출력할 수 있다.The additional path transfer function unit 200 may receive the first to n-th counter noise signals 30 and output the first to n-th sound 40.
구체적으로, 부가경로 전달함수부(200)는 제1 반대소음신호(30)가 입력되는 경우, 제1 반대소음신호(30)에 대한 제1 음향(40)을 출력하고, 제2 반대소음신호(30)가 입력되는 경우, 제2 반대소음신호(30)에 대한 제2 음향(40)을 출력하고, 제n 반대소음신호(30)가 입력되는 경우, 제n 반대소음신호(30)에 대한 제n 음향(40)을 출력할 수 있다. Specifically, when the first opposite noise signal 30 is input, the additional path transfer function unit 200 outputs the first sound 40 with respect to the first opposite noise signal 30 and the second opposite noise signal. When 30 is input, the second sound 40 is output to the second counter noise signal 30, and when the n-th counter noise signal 30 is input, the n-th counter noise signal 30 is input. The n th sound 40 may be output.
감지부(300)는 제1 및 제2 소음을 감지하고, 제1 오차신호(60) 및 제2 오차신호(60)를 출력할 수 있다.The detector 300 may detect the first and second noises and may output the first error signal 60 and the second error signal 60.
구체적으로, 감지부(300)는 제1 음향(40)이 출력되는 동안 제1 소음을 감지하여 제1 오차신호(60)를 출력할 수 있고, 제2 음향(40)이 출력되는 동안 제2 소음을 감지하여 제2 오차신호(60)를 출력할 수 있다.In detail, the detector 300 may detect the first noise and output the first error signal 60 while the first sound 40 is output, and the second while the second sound 40 is output. The second error signal 60 may be output by detecting the noise.
도 2는 도 1에 도시된 능동소음제어 알고리즘부의 일 예를 설명하기 위한 도식도이다. 도 1 및 도 2를 참조하면, 실시 형태에 따른 능동소음제어 알고리즘부(100)는 적응필터(adaptive filters)(110), 지연시간 분석기(group delay analyzer)(120), 부가경로 전달함수 모델(secondary path transfer function model)(130) 및 업데이트 알고리즘(update algorithm)(140)을 포함할 수 있다.FIG. 2 is a schematic diagram illustrating an example of an active noise control algorithm shown in FIG. 1. 1 and 2, the active noise control algorithm unit 100 according to the embodiment includes an adaptive filter 110, a group delay analyzer 120, and an additional path transfer function model ( secondary path transfer function model 130 and an update algorithm 140.
적응필터(110)는 참조신호(10)를 입력받고, 필터링된 참조신호를 출력할 수 있다. 구체적으로, 적응필터(110)는 입력된 참조신호(10)를 필터링하여 필터링된 참조신호를 생성하고, 생성된 필터링된 참조신호를 출력할 수 있다. 필터링된 참조신호는 위상반전을 통해 반대소음신호(30)로 변환될 수 있다. 여기서, 반대소음신호(30)에는 부가신호(20)가 더해질 수 있다.The adaptive filter 110 may receive the reference signal 10 and output the filtered reference signal. In detail, the adaptive filter 110 may filter the input reference signal 10 to generate a filtered reference signal and output the generated filtered reference signal. The filtered reference signal may be converted into an opposite noise signal 30 through phase inversion. Here, the additional signal 20 may be added to the opposite noise signal 30.
지연시간 분석기(120)는 오차신호(60)와 부가신호(20)를 입력받고, 지연시간 오차신호(group delay error signal)(70)를 출력할 수 있다. 여기서, 지연시간 오차신호(70)는 시스템 주변의 온도나 압력 등에 의해 변화된 위상오차일 수 있다.The delay time analyzer 120 may receive the error signal 60 and the additional signal 20, and output a group delay error signal 70. Here, the delay time error signal 70 may be a phase error changed by temperature or pressure around the system.
구체적으로, 지연시간 분석기(120)는 시스템 주변의 온도나 압력 등에 의한 시스템의 지연시간 변화를 계산하기 위하여, 부가신호(20)와 오차신호(60)를 비교하여 지연시간 오차신호(70)를 생성하고, 생성된 지연시간 오차신호(70)를 출력한다. 일 예로, 지연시간 분석기(120)는 부가신호(20)와 오차신호(60)의 해당주파수 성분들 사이의 상관관계(correlation)를 분석하는 방법을 이용하여 지연시간 오차신호(70)를 생성할 수 있다. 여기서, 상관관계를 분석하는 것은 상관관계 분석기(correlation analyzer)를 이용하는 것일 수 있다. In detail, the delay time analyzer 120 compares the delay time error signal 70 by comparing the additional signal 20 with the error signal 60 to calculate a change in the delay time of the system due to temperature or pressure around the system. And the generated delay time error signal 70 is output. For example, the delay time analyzer 120 may generate the delay time error signal 70 by using a method of analyzing a correlation between the additional signal 20 and corresponding frequency components of the error signal 60. Can be. Here, analyzing the correlation may be to use a correlation analyzer.
부가경로 전달함수 모델(130)은 지연시간 오차신호(70)와 참조신호(10)를 입력받고, 참조소음신호(80)를 출력할 수 있다. 구체적으로, 부가경로 전달함수 모델(130)은 지연시간 오차신호(70)를 이용하여 부가경로 전달함수가 알고리즘에 미치는 영향을 보상하도록 실시간으로 업데이트 된다. 이때, 업데이트된 부가경로 전달함수 모델(130)에는 참조신호(10)가 적용되어 참조소음신호(80)가 생성될 수 있다.The additional path transfer function model 130 may receive the delay time error signal 70 and the reference signal 10 and output the reference noise signal 80. Specifically, the additional path transfer function model 130 is updated in real time to compensate for the influence of the additional path transfer function on the algorithm using the delay time error signal 70. In this case, the reference signal 10 may be applied to the updated additional path transfer function model 130 to generate the reference noise signal 80.
업데이트 알고리즘(140)은 참조소음신호(80)와 오차신호(60)가 입력되고, 개선적응필터(90)를 출력할 수 있다. 구체적으로, 업데이트 알고리즘(140)은 참조소음신호(80)와 오차신호(60)를 곱하여 개선적응필터(90)를 생성할 수 있다. 여기서, 참조소음신호(80)와 오차신호(60)에는 수렴요소(step-size)라는 상수가 더 곱해질 수 있다.The update algorithm 140 may receive the reference noise signal 80 and the error signal 60, and output the improvement adaptation filter 90. In detail, the update algorithm 140 may generate the improvement adaptation filter 90 by multiplying the reference noise signal 80 and the error signal 60. Here, the reference noise signal 80 and the error signal 60 may be further multiplied by a constant called a step-size.
적응필터(110)는 개선적응필터(90)를 더 입력받고, 필터링된 참조신호를 출력할 수 있다. 구체적으로, 적응필터(110)는 개선적응필터(90)와 제1 적응필터(110)를 더하여 제2 적응필터(110)를 생성할 수 있다. 여기서, 제1 적응필터(110)는 사전에 값이 설정되며, 일반적으로 0의 값으로 이루어질 수 있고, 제2 적응필터(110)는 제1 적응필터(110)가 업데이트된 것일 수 있다. 제2 적응필터(110)는 참조신호(10)를 필터링하여 필터링된 참조신호를 생성하고, 생성된 필터링된 참조신호를 출력할 수 있다. The adaptive filter 110 may further receive the improved adaptive filter 90 and output the filtered reference signal. In detail, the adaptive filter 110 may generate the second adaptive filter 110 by adding the improved adaptive filter 90 and the first adaptive filter 110. In this case, the first adaptive filter 110 may have a value set in advance, and may be generally set to 0, and the second adaptive filter 110 may have an updated first adaptive filter 110. The second adaptive filter 110 may filter the reference signal 10 to generate a filtered reference signal, and output the generated filtered reference signal.
여기서, 부가신호(20)는 가청주파수 외의 신호일 수 있다. 구체적으로, 가청주파수는 약 20Hz 내지 20.000Hz이기 때문에 부가신호(20)는 20Hz 이하인 초저주파 또는 20,000Hz 이상인 초음파일 수 있다. 하지만, 일반적인 스피커는 동적 특성에 한계로 인해 20Hz 이하의 소리는 재생이 잘 안될 수 있다. 따라서, 부가신호(20)는 초저주파를 제외한 초음파일 수 있다. Here, the additional signal 20 may be a signal other than an audible frequency. Specifically, since the audible frequency is about 20 Hz to 20.000 Hz, the additional signal 20 may be an ultra low frequency of 20 Hz or less or an ultrasonic wave of 20,000 Hz or more. However, due to the limitation of the dynamic characteristics of a typical speaker, sounds below 20Hz may not play well. Therefore, the additional signal 20 may be ultrasonic waves excluding ultra low frequencies.
가청주파수로 부가신호(20)를 생성하고, 부가신호(20)와 반대소음신호(30)를 이용하여 지연시간 오차신호(70)를 계산하는 경우에는, 가청주파수의 부가신호(20)로 인한 추가적인 소음이 발생할 수 있다. 더욱이, 그 주파수가 소음 스펙트럼이 가지는 주파수대역 안에 포함되는 성분이라면, 소음제어방법을 수행하는 알고리즘의 안정성 및 수렴성에 문제가 발생할 수 있다.When the additional signal 20 is generated at an audible frequency and the delay time error signal 70 is calculated using the additional signal 20 and the opposite noise signal 30, the additional signal 20 is generated due to the additional signal 20 of the audio frequency. Additional noise may occur. Moreover, if the frequency is a component included in the frequency band of the noise spectrum, problems may occur in the stability and convergence of the algorithm for performing the noise control method.
이에 반해, 실시 형태에 따른 소음제어방법은 가청주파수 외의 신호로 부가신호(20)를 생성하고, 부가신호(20)와 반대소음신호(30)를 이용하여 지연시간 오차신호(70)를 계산하기 때문에, 부가신호(20)로 인한 추가소음이 들리지 않는다. 그리고 보통의 소음은 가청주파수 대역에서 발생하므로, 소음제어방법을 수행하는 알고리즘의 안정성 및 수렴성에 문제가 발생하지 않는 이점이 있다.In contrast, the noise control method according to the embodiment generates the additional signal 20 using a signal other than an audible frequency, and calculates the delay time error signal 70 using the additional signal 20 and the opposite noise signal 30. Therefore, additional noise due to the additional signal 20 is not heard. In addition, since normal noise is generated in the audible frequency band, there is an advantage that a problem does not occur in stability and convergence of the algorithm for performing the noise control method.
도 3은 도 2에 도시된 부가경로 전달함수 모델의 제1 실시예다.3 is a first embodiment of the additional path transfer function model shown in FIG. 2.
도 2 및 도 3을 참조하면, 부가경로 전달함수 모델(130)은 일반적인 능동소음제어 방법에서의 트랜스버설 필터(transversal filter)형태인 초기 부가경로 전달함수 초기모델(131) 및 순수 지연 필터(132)를 포함할 수 있다.2 and 3, the additional path transfer function model 130 is an initial additional path transfer function initial model 131 and a pure delay filter 132 in the form of a transversal filter in a general active noise control method. ) May be included.
부가경로 전달함수 초기모델(131)은 공장에서 출고 전이나 능동소음제어 시스템 설치 후 생성될 수 있다. 구체적으로, 가청주파수 대역의 백색잡음신호를 생성한 후, 오차 마이크로폰에서 이를 감지하여 생성할 수 있다.The additional path transfer function initial model 131 may be generated before leaving the factory or after installing the active noise control system. Specifically, after generating the white noise signal of the audio frequency band, it may be generated by detecting it in the error microphone.
부가경로 전달함수 초기모델(131)은 부가경로 전달함수의 임펄스응답을 모사하는 유한한 길이의 필터로 표현될 수 있다.The additional path transfer function initial model 131 may be represented by a finite length filter that simulates an impulse response of the additional path transfer function.
순수 지연 필터(132)는 지연시간 분석기(120)로부터 입력되는 지연시간 오차신호(70)에 따라 실시간으로 업데이트될 수 있다.The pure delay filter 132 may be updated in real time according to the delay time error signal 70 input from the delay time analyzer 120.
구체적으로, 오차신호(60)의 제곱 값이 최소화되도록 참조신호(10)와 오차신호(60)를 이용하여, 적응필터(110)의 계수를 매 샘플마다 업데이트 시키며, 이러한 경우에는 광대역 소음을 제어할 수 있다.Specifically, by using the reference signal 10 and the error signal 60 to update the coefficient of the adaptive filter 110 for each sample to minimize the square of the error signal 60, in this case, the broadband noise is controlled can do.
도 4는 도 2에 도시된 부가경로 전달함수 모델의 제2 실시예이고, 도 5는 도 4에 도시된 부가경로 전달함수 초기모델의 도식도이고, 도 6은 도 4에 도시된 부가경로 전달함수 업데이트 알고리즘의 도식도이다.FIG. 4 is a second embodiment of the additional path transfer function model shown in FIG. 2, FIG. 5 is a schematic diagram of the initial model of the additional path transfer function shown in FIG. 4, and FIG. 6 is the additional path transfer shown in FIG. 4. Schematic of the function update algorithm.
도 1 내지 도 6을 참조하면, 부가경로 전달함수 모델(130)은 주파수 별로 병렬적으로 처리가 될 수 있다. 구체적으로, 한 주파수에서 사인 신호 및 코사인 신호는 부가경로 전달함수 초기모델(133)과 부가경로 전달함수 업데이트 알고리즘(134)에 의해 필터링된다. 지연시간 오차신호(70)는 각각의 부가경로 전달함수 업데이트 알고리즘(134)에 입력된다.1 to 6, the additional path transfer function model 130 may be processed in parallel for each frequency. Specifically, the sine signal and the cosine signal at one frequency are filtered by the additional path transfer function initial model 133 and the additional path transfer function update algorithm 134. The delay time error signal 70 is input to each additional path transfer function update algorithm 134.
부가경로 전달함수 초기모델(133)은 공장에서 출고 전이나 능동소음제어 시스템 설치 후 생성될 수 있다. 구체적으로, 가청주파수 대역의 백색잡음신호를 생성한 후, 오차 마이크로폰으로 감지하여 생성할 수 있다.The additional path transfer function initial model 133 may be generated before leaving the factory or after installing the active noise control system. Specifically, after generating a white noise signal of an audible frequency band, it can be generated by detecting with an error microphone.
부가경로 전달함수 초기모델(133)은 부가경로 전달함수를 주파수 별 크기와 위상의 정보로 분류할 수 있다. 부가경로 전달함수 초기모델(133)은 분류된 주파수 별 사인 및 코사인 신호를 이용하여 각 주파수의 크기와 위상 정보로부터 해당하는 이득 값을 구하고, 이를 곱하고 더하여 참조소음신호(80)를 얻어낼 수 있다. 각각의 이득 값은 사전에 측정된 부가경로 전달함수에서 계산될 수 있으며, 그 값은 고정된다.The additional path transfer function initial model 133 may classify the additional path transfer function into information of size and phase for each frequency. The additional path transfer function initial model 133 may obtain a reference noise signal 80 by multiplying and adding a gain value from the magnitude and phase information of each frequency using the classified sine and cosine signals. . Each gain value can be calculated from a previously measured sidepath transfer function, which is fixed.
구체적으로, 부가경로 전달함수 초기모델(133)의 주파수 별 크기와 위상은 도 6과 같이 계산하여 필터링될 수 있다. 사전에 측정하여 부가경로 전달함수 초기모델(133)을 구할 때, 시스템 초기 지연시간을 구할 수 있다.Specifically, the size and phase of each frequency of the initial path transfer function initial model 133 may be calculated and filtered as shown in FIG. 6. When obtaining the additional path transfer function initial model 133 by measuring in advance, the system initial delay time can be obtained.
알고리즘이 작동하게 되면, 현재와 초기 지연시간의 차이 값인 지연시간 오차신호(70)를 부가경로 전달함수 업데이트 알고리즘(134)에 적용한다. 지연시간 오차신호(70)는 사전에 계산된 해당 주파수의 이득 값이 곱해지고, 그 값의 위상만큼을 보상한다.When the algorithm is activated, the delay time error signal 70, which is the difference between the current and initial delay time, is applied to the additional path transfer function update algorithm 134. The delay time error signal 70 is multiplied in advance by a gain value of the corresponding frequency, and compensates for the phase of the value.
일 예로, [수학식 1]과 [수학식 2]를 이용하여 계산할 수 있다.For example, it may be calculated using [Equation 1] and [Equation 2].
[수학식 1][Equation 1]
[수학식 2][Equation 2]
여기서, fk는 k번째 주파수이고, n은 샘플(sample)이고, Δ는 지연시간 분석기(120)에서 계산된 지연시간 오차신호(70)이다.Here, f k is the k th frequency, n is a sample, and Δ is the delay time error signal 70 calculated by the delay time analyzer 120.
여기서, 지연시간 오차신호(70)는 사전에 계산된 해당 주파수의 이득 값이 곱해지고, 그 값의 위상만큼을 보상하고자 부가경로 전달함수 초기모델(133)의 방법과 같이 적용할 수 있다.In this case, the delay time error signal 70 may be multiplied in advance by a gain value of the corresponding frequency, and may be applied in the same manner as the method of the additional path transfer function initial model 133 to compensate for the phase of the value.
부가경로 전달함수 업데이트 알고리즘(134)은 덕트(duct)구조 등과 같이 간단한 구조에서는 소리가 평면파의 형태로 전달되기 때문에, 물리적인 거리로부터 소리가 도달하는 시간을 예측할 수 있다. 마찬가지로, 이와 같은 시스템에서는 온도의 변화량만 안다면, 그에 따른 부가경로 전달함수의 위상 변화를 예측할 수 있다.The additional path transfer function update algorithm 134 may predict the time at which the sound arrives from the physical distance because the sound is transmitted in the form of a plane wave in a simple structure such as a duct structure. Similarly, in such a system, if the change in temperature is known, the phase change of the additional path transfer function can be predicted accordingly.
이상적인 시스템에서 주파수 별 지연시간은 동일하며, 주파수영역에서의 위상은 선형의 형태를 가진다. 부가신호(20)는 사람이 들을 수 없는 가청주파수 외의 주파수 신호를 사용하여, 추가로 인한 소음은 들리지 않지만 센서로부터 측정이 가능하게 된다. 따라서, 부가신호(20)로 인한 추가적인 소음은 발생하지 않아 본래의 목적인 소음제어의 성능을 저하시키지 않을 수 있다.In an ideal system, the delay times for each frequency are the same, and the phase in the frequency domain is linear. The additional signal 20 uses a frequency signal other than an audible frequency that is inaudible to humans, so that noise due to addition is not heard but can be measured from the sensor. Therefore, additional noise due to the additional signal 20 does not occur and may not degrade the performance of the original noise control.
여기서, 제2 실시예에 따른 부가경로 전달함수 모델은 소음이 주기적인 혹은 준 주기적인 특성을 가질 때, 우수한 성능을 보일 수 있다.Here, the additional path transfer function model according to the second embodiment may exhibit excellent performance when the noise has a periodic or semi-periodic characteristic.
도 7은 도 2에 도시된 지연시간 분석기의 도식도이고, 도 8은 도 2에 도시된 지연시간 분석기에서 지연시간의 변화를 분석하는 일 예를 도시한다.7 is a schematic diagram of the delay analyzer illustrated in FIG. 2, and FIG. 8 illustrates an example of analyzing a change in delay time in the delay analyzer illustrated in FIG. 2.
도 7 및 도 8을 참조하면, 지연시간 분석기(120)에는 하이패스 필터(high pass filter, HPF)(미도시)가 포함될 수 있다. 지연시간 분석기(120)에 하이패스 필터가 포함되면, 오차신호(60)를 하이패스 필터링할 수 있다. 구체적으로, 지연시간 분석기(120)에 전송되는 오차신호(60)는 소음에 따른 가청주파수 대역과 부가신호(20)에 따른 초음파 대역을 포함할 수 있다. 따라서, 오차신호(60)를 하이패스 필터링하면, 오차신호(60)의 가청주파수 대역은 필터링되고, 초음파 대역만이 남게된다. 그러므로, 오차신호(60)의 초음파 대역과 부가신호(20)의 상관관계를 분석하는 방법을 이용하여 지연시간의 변화를 계산할 수 있다.7 and 8, the delay analyzer 120 may include a high pass filter (HPF) (not shown). When the high pass filter is included in the delay analyzer 120, the error signal 60 may be high pass filtered. Specifically, the error signal 60 transmitted to the delay time analyzer 120 may include an audible frequency band according to noise and an ultrasonic band according to the additional signal 20. Therefore, when the high pass filtering the error signal 60, the audio frequency band of the error signal 60 is filtered, leaving only the ultrasonic band. Therefore, a change in delay time may be calculated using a method of analyzing a correlation between the ultrasonic band of the error signal 60 and the additional signal 20.
이와 같이, 지연시간 분석기(120)는 하이패스 필터를 포함하고, 오차신호(60)를 하이패스 필터링한 후, 부가경로 전달함수의 지연시간의 변화를 계산하기 때문에, 오차신호(60)에 포함된 가청주파수 대역이 필터링되어 오차신호(60)에 포함된 초음파 대역만으로 부가경로 전달함수의 지연시간의 변화를 계산할 수 있다. 따라서, 부가경로 전달함수의 지연시간의 변화의 계산이 보다 더 간단해질 수 있는 이점이 있다.As described above, the delay time analyzer 120 includes the high pass filter, calculates the change in the delay time of the additional path transfer function after the high pass filtering of the error signal 60, and thus includes the error signal 60 in the error signal 60. The audible frequency band is filtered to calculate a change in delay time of the additional path transfer function using only the ultrasonic band included in the error signal 60. Therefore, there is an advantage that the calculation of the change in delay time of the additional path transfer function can be made simpler.
또한, 지연시간 분석기(120)는 부가신호(20) 및 오차신호(60)의 해당주파수 성분들을 분석하고, 부가신호(20) 및 오차신호(60)의 위상 차를 측정하여 지연시간 오차신호(70)를 계산할 수 있다. 따라서, 부가신호(20)를 이용하여 지연시간 오차신호(70)를 계산하는 과정이 간단해질 수 있다.In addition, the delay time analyzer 120 analyzes corresponding frequency components of the additional signal 20 and the error signal 60, and measures the phase difference between the additional signal 20 and the error signal 60 to detect the delay time error signal ( 70) can be calculated. Therefore, the process of calculating the delay time error signal 70 using the additional signal 20 can be simplified.
이하에서는, 실시 형태에 따른 소음제어방법을 설명하도록 한다.Hereinafter, the noise control method according to the embodiment will be described.
도 9는 실시 형태에 따른 소음제어방법을 설명하기 위한 순서도이다.9 is a flowchart illustrating a noise control method according to the embodiment.
도 1 내지 도 5 및 도 9를 참조하면, 실시 형태에 따른 소음제어방법은 제1 출력단계(S10), 제1 감지단계(S20), 제2 출력단계(S30), 제2 감지단계(S40) 및 제3 출력단계(S50)를 포함할 수 있다. 먼저, 제1 출력단계(S10)는 참조신호(10)를 입력받아 제1 반대소음신호(30)를 생성하고, 제1 음향(40)을 출력한다. 구체적으로, 참조신호(10)를 입력받고, 부가경로 전달함수 모델(130)을 이용하여 제1 적응필터(110)를 생성하고, 참조신호(10)를 제1 적응필터(110)에 적용하여 제1 반대소음신호(30)를 생성하고, 제1 반대소음신호(30)에 대한 제1 음향(40)을 스피커와 같은 음향 출력수단 등을 이용하여 출력할 수 있다.1 to 5 and 9, the noise control method according to the embodiment includes a first output step S10, a first detection step S20, a second output step S30, and a second detection step S40. ) And a third output step S50. First, the first output step S10 receives the reference signal 10, generates a first reverse noise signal 30, and outputs a first sound 40. Specifically, the reference signal 10 is input, the first adaptive filter 110 is generated using the additional path transfer function model 130, and the reference signal 10 is applied to the first adaptive filter 110. The first counter noise signal 30 may be generated, and the first sound 40 with respect to the first counter noise signal 30 may be output using sound output means such as a speaker.
제1 감지단계(S20)는 제1 음향(40)이 출력되는 동안 제1 소음을 감지한다. 구체적으로, 제1 음향(40)과 소음(50)의 중첩에 의해 소음이 덜 상쇄되면 제1 소음이 오차 마이크로폰에 의해 감지될 수 있다.The first sensing step S20 detects the first noise while the first sound 40 is output. Specifically, when noise is less canceled by the overlap of the first sound 40 and the noise 50, the first noise may be detected by the error microphone.
제2 출력단계(S30)는 제1 소음이 감지되는 경우, 제2 반대소음신호(30)를 생성하고, 제2 음향(40)을 출력한다. 구체적으로, 오차 마이크로폰이 제1 소음을 감지하는 경우, 지연시간의 변화를 계산하기 위해 부가신호(20)를 생성하고, 부가신호(20)를 제1 반대소음신호(30)에 더하여 제2 반대소음신호(30)를 생성하고, 제2 반대소음신호(30)를 출력할 수 있다. 여기서, 부가신호(20)는 가청주파수 외의 신호일 수 있다.When the first noise is detected, the second output step S30 generates a second counter noise signal 30 and outputs a second sound 40. Specifically, when the error microphone detects the first noise, the additional signal 20 is generated to calculate the change in delay time, and the additional signal 20 is added to the first counter noise signal 30 to counter the second noise. The noise signal 30 may be generated and the second counter noise signal 30 may be output. Here, the additional signal 20 may be a signal other than an audible frequency.
제2 감지단계(S40)는 제2 음향(40)이 출력되는 동안 제2 소음을 감지한다. 구체적으로, 제2 음향(40)과 소음(50)의 중첩에 의해 소음(50)이 덜 상쇄되면 제2 소음이 오차 마이크로폰에 의해 감지될 수 있다.The second sensing step S40 detects the second noise while the second sound 40 is output. Specifically, if the noise 50 is less canceled by the overlap of the second sound 40 and the noise 50, the second noise may be detected by the error microphone.
제3 출력단계(S50)는 제2 소음이 감지되는 경우, 지연시간 오차신호(70)를 생성하고, 제3 음향(40)을 출력한다. 구체적으로, 오차 마이크로폰이 제2 소음을 감지하는 경우, 지연시간 분석기(120)는 부가신호(20)와 제2 소음에 의한 신호(60)를 비교하여 지연시간 오차신호(70)를 생성하고, 부가경로 전달함수 초기모델(131, 133)은 지연시간 오차신호(70)에 의해 실시간으로 업데이트되고, 지연시간 오차신호(70)에 의해 업데이트된 부가경로 전달함수 모델(130)에 참조신호(10)를 적용하여 참조소음신호(80)를 생성하고, 참조소음신호(80)와 제2 소음에 의한 신호(60) 및 수렴요소를 곱하여 개선적응필터(90)를 생성하고, 생성된 개선적응필터(90)와 제1 적응필터(110)를 더하여 제2 적응필터(110)를 생성하고, 참조신호(10)를 제2 적응필터(110)에 적용하여 제3 반대소음신호(30)를 생성하고, 제3 반대소음신호(30)에 대한 제3 음향(40)을 출력할 수 있다. 여기서, 제3 출력단계에서 지연시간 오차신호(70)를 생성하는 것은 제2 소음에 의한 신호(60)를 하이패스 필터링한 후, 부가신호(20)와 비교하여 지연시간 오차신호(70)를 생성하는 것일 수 있다. When the second noise is sensed, the third output step S50 generates a delay time error signal 70 and outputs a third sound 40. Specifically, when the error microphone detects the second noise, the delay time analyzer 120 generates a delay time error signal 70 by comparing the additional signal 20 and the signal 60 due to the second noise, The additional path transfer function initial models 131 and 133 are updated in real time by the delay time error signal 70, and the reference signal 10 is added to the additional path transfer function model 130 updated by the delay time error signal 70. ) Generates a reference noise signal (80), multiplies the reference noise signal (80) by the second noise signal (60) and convergence elements to generate an improvement adaptation filter (90), and generates the improved adaptation filter 90 and the first adaptive filter 110 are added to generate the second adaptive filter 110, and the reference signal 10 is applied to the second adaptive filter 110 to generate the third opposite noise signal 30. In addition, the third sound 40 with respect to the third counter noise signal 30 may be output. Here, the generation of the delay time error signal 70 in the third output step includes high pass filtering the signal 60 due to the second noise, and then compares the delay time error signal 70 with the additional signal 20. It may be to produce.
여기서, 제1 출력단계에서 제1 반대소음신호(30)를 생성하는 것은 참조신호(10)의 주파수를 분석하고, 분석된 참조신호(10)의 주파수 중 제어하고자 하는 주파수를 선택하여 제1 반대소음신호(30)를 생성하는 것일 수 있다.Here, generating the first counter noise signal 30 in the first output stage analyzes the frequency of the reference signal 10, selects a frequency to be controlled among the frequencies of the analyzed reference signal 10, and then selects the first counter noise. The noise signal 30 may be generated.
이와 같이, 실시 형태에 따른 소음제어방법은 제1 소음을 감지하는 경우, 부가신호(20)를 생성하여 지연시간 오차신호(70)를 생성하기 때문에, 주변의 온도나 압력 등이 변하여 소리의 속도가 바뀌는 불안정한 부가경로 전달함수를 가지는 환경에서도 소음을 제어할 수 있는 이점이 있다.As described above, the noise control method according to the embodiment generates the delay time error signal 70 by generating the additional signal 20 when the first noise is detected. There is an advantage that the noise can be controlled even in an environment having an unstable additional path transfer function that is changed.
또한, 실시 형태에 따른 소음제어방법은 부가경로 전달함수 초기모델(131, 133)이 지연시간 오차신호(70)에 의해 실시간으로 업데이트되고, 참조소음신호(80)와 제2 소음에 의한 신호(60)를 이용하여 제2 적응필터(110)를 생성하고, 참조신호(10)를 제2 적응필터(110)에 적용하여 제3 반대소음신호(30)를 생성하기 때문에, 온도나 압력에 따라 부가경로 전달함수의 지연시간이 주파수 별로 선형적으로 변하는 어떠한 환경에서도 소음을 제어할 수 있는 이점이 있다.In addition, in the noise control method according to the embodiment, the additional path transfer function initial models 131 and 133 are updated in real time by the delay time error signal 70, and the reference noise signal 80 and the signal caused by the second noise ( Since the second adaptive filter 110 is generated using the reference numeral 60 and the reference signal 10 is applied to the second adaptive filter 110 to generate the third counter noise signal 30, the second adaptive filter 110 is generated according to the temperature or the pressure. There is an advantage that the noise can be controlled in any environment where the delay time of the additional path transfer function varies linearly with frequency.
또한, 실시 형태에 따른 소음제어방법은 제2 소음에 의한 신호(60)를 하이패스 필터링한 후, 부가신호(20)와 비교하여 지연시간 오차신호(70)를 생성하기 때문에, 제2 소음에 의한 신호(60)에 포함된 가청주파수 대역이 필터링되어 제2 소음에 의한 신호(60)에 포함된 초음파 대역만으로 부가경로 전달함수의 지연시간의 변화를 계산할 수 있다. 따라서, 부가경로 전달함수의 지연시간의 변화의 계산이 보다 더 간단해질 수 있는 이점이 있다.In addition, the noise control method according to the embodiment generates a delay time error signal 70 in comparison with the additional signal 20 after high pass filtering the signal 60 caused by the second noise. The audible frequency band included in the signal 60 may be filtered to calculate a change in delay time of the additional path transfer function using only the ultrasonic band included in the signal 60 due to the second noise. Therefore, there is an advantage that the calculation of the change in delay time of the additional path transfer function can be made simpler.
또한, 실시 형태에 따른 소음제어방법은 참조신호(10)의 주파수를 분석하고, 분석된 참조신호(10)의 주파수 중 제어하고자 하는 주파수를 선택하여 반대소음신호(30)를 생성하기 때문에, 원하는 주파수 소음만 저감하는 것이 가능하며, 부가신호(20)를 이용하여 지연시간의 변화를 계산하는 과정이 간단해질 수 있는 이점이 있다.In addition, since the noise control method according to the embodiment analyzes the frequency of the reference signal 10 and selects a frequency to be controlled among the frequencies of the analyzed reference signal 10 to generate the opposite noise signal 30, It is possible to reduce only the frequency noise, and there is an advantage that the process of calculating the change in delay time using the additional signal 20 can be simplified.
그리고, 실시 형태에 따른 소음제어방법은 가청주파수 외의 주파수 신호를 부가신호(20)로 이용하기 때문에, 가청주파수의 신호를 부가신호(20)로 이용할 때 발생하는 추가적인 소음을 발생하지 않고 지연시간의 변화를 감지하면서 동시에 이를 보상할 수 있는 이점이 있다.In addition, since the noise control method according to the embodiment uses a frequency signal other than the audible frequency as the additional signal 20, the delay time is not generated without generating additional noise generated when the signal of the audio frequency is used as the additional signal 20. There is an advantage in that it can detect and compensate for changes.
도 10은 부가경로 전달함수 초기모델을 생성하는 방법을 설명하기 위한 순서도이다. 여기서, 부가경로 전달함수 초기모델(131, 133)은 능동소음제어를 작동하기 전에 오프라인(off-line)으로 생성할 수 있다.10 is a flowchart illustrating a method of generating an additional path transfer function initial model. Here, the additional path transfer function initial models 131 and 133 may be generated off-line before the active noise control is activated.
도 1 내지 도 5 및 도 10을 참조하면, 제1 출력단계 이전에 부가경로 전달함수 초기모델(131, 133)을 생성하는 방법은 먼저, 백색잡음신호를 생성하고, 제 4음향을 출력한다(S101). 구체적으로, 가청주파수 대역의 백색잡음신호를 생성하고, 생성된 백색잡음신호에 대한 제4 음향을 출력할 수 있다.1 to 5 and 10, the method of generating the additional path transfer function initial models 131 and 133 before the first output step first generates a white noise signal and outputs a fourth sound ( S101). Specifically, a white noise signal of an audible frequency band may be generated, and a fourth sound of the generated white noise signal may be output.
제4 음향이 출력되는 동안 제5 음향을 감지하고, 부가경로 전달함수 초기모델(131, 133)을 생성한다(S102). 구체적으로, 제4 음향이 출력되는 동안 오차 마이크로폰에 의해 감지된 제5 음향에 의한 전달신호와 백색잡음신호를 이용하여 부가경로 전달함수 초기모델(131, 133)을 생성한다.While the fourth sound is output, the fifth sound is sensed and the additional path transfer function initial models 131 and 133 are generated (S102). Specifically, the additional path transfer function initial models 131 and 133 are generated by using the white noise signal and the transmission signal of the fifth sound detected by the error microphone while the fourth sound is output.
이와 같이, 실시 형태에 따른 소음제어방법에 의하면, 백색잡음신호를 생성하고, 백색잡음신호에 대한 음향을 출력하여 부가경로 전달함수 초기모델(131, 133)을 생성하기 때문에, 출력된 음향에 의한 전달신호만으로도 부가경로 전달함수에 따른 부가경로 전달함수 초기모델을 보다 더 간단하게 생성할 수 있다. 여기서, 부가경로 전달함수 초기모델(131, 133)은 LMS(Least Mean Square) 방법으로도 생성할 수 있다.As described above, according to the noise control method according to the embodiment, since the white noise signal is generated, the sound for the white noise signal is output, and the additional path transfer function initial models 131 and 133 are generated. The initial signal of the additional path transfer function according to the additional path transfer function may be generated more simply by using the transmitted signal alone. Here, the additional path transfer function initial models 131 and 133 may also be generated by a Least Mean Square (LMS) method.
도 11은 실시 형태에 따른 소음제어방법을 수행하는 알고리즘의 순서도이다.11 is a flowchart of an algorithm for performing the noise control method according to the embodiment.
도 1 내지 도 5 및 도 11을 참조하면, 실시 형태에 따른 소음제어방법은 감지단계, 부가신호 생성단계, 반대소음신호 생성단계 및 출력 단계를 포함할 수 있다. 먼저, 감지단계는 제1 마이크로폰이 제1 샘플에 대한 제1 참조소음을 감지하고, 제2 마이크로폰이 제1 소음을 감지한다. 여기서, 제1 마이크로폰은 소음(50)을 감지하는 마이크로폰이고, 제2 마이크로폰은 상술한 오차마이크로폰일 수 있다.1 to 5 and 11, the noise control method according to the embodiment may include a sensing step, an additional signal generation step, a counter-noise signal generation step and an output step. First, in the sensing step, the first microphone detects the first reference noise for the first sample, and the second microphone detects the first noise. Here, the first microphone may be a microphone for detecting the noise 50, and the second microphone may be the above-described error microphone.
부가신호 생성단계는 제1 마이크로폰에서 감지된 제1 참조소음에 의한 제1 참조신호(10)와 제2 마이크로폰에서 감지된 제1 소음에 의한 제1 오차신호(60)가 전송되는 경우, 제1 부가신호(20)를 생성한다. 구체적으로, 제1 부가신호(20)는 신호 생성기(signal generator) 등에 의해 생성될 수 있다. 여기서, 제1 부가신호(20)는 가청주파수 외의 신호일 수 있다.The additional signal generating step is performed when the first reference signal 10 by the first reference noise detected by the first microphone and the first error signal 60 by the first noise detected by the second microphone are transmitted. The additional signal 20 is generated. In detail, the first additional signal 20 may be generated by a signal generator or the like. Here, the first additional signal 20 may be a signal other than an audible frequency.
반대소음신호 생성단계는 제1 참조신호(10), 제1 오차신호(60) 및 제1 부가신호(20)를 이용하여 제1 반대소음신호(30)를 생성한다. 구체적으로, 반대소음신호 생성단계는 지연시간 분석기(120)가 제1 부가신호(20)와 제1 오차신호(60)를 비교하여 제1 지연시간 오차신호(70)를 생성하는 지연시간 오차신호 생성단계, 부가경로 전달함수 모델(130)이 제1 지연시간 오차신호(70)를 이용하여 부가경로 전달함수 초기모델(131, 133)을 실시간으로 업데이트하여 업데이트된 부가경로 전달함수 모델(130)을 생성하고, 제1 참조신호(10)를 업데이트된 부가경로 전달함수 모델(130)에 적용하여 제1 참조소음신호(80)를 생성하는 참조소음신호 생성단계, 제1 오차신호(60) 및 수렴요소를 제1 참조소음신호(80)와 곱하여 제1 개선적응필터(90)를 생성하고, 제1 개선적응필터(90)와 제1 적응필터(110)를 더하여 제2 적응필터(110)를 생성하는 적응필터 생성단계 및 제1 참조신호(10)를 제2 적응필터(110)에 적용한 후, 제1 부가신호(20)를 더하여 제1 반대소음신호(30)를 생성하는 참조신호 적용단계를 포함한다. 여기서, 지연시간 오차신호 생성단계는 제1 오차신호(60)를 하이패스 필터링한 후, 제1 부가신호(20)와 비교하여 제1 지연시간 오차신호(70)를 생성할 수 있다. 또한, 반대소음신호 생성단계는 제1 참조신호(10)의 주파수를 분석하고, 분석된 제1 참조신호(10)의 주파수 중 제어하고자 하는 주파수를 선택하여 생성될 수 있다.In the opposite noise generating step, the first opposite noise signal 30 is generated using the first reference signal 10, the first error signal 60, and the first additional signal 20. Specifically, in the opposite noise generation step, the delay time error signal in which the delay time analyzer 120 generates the first delay time error signal 70 by comparing the first additional signal 20 and the first error signal 60. Generating step, the additional path transfer function model 130 updates the additional path transfer function initial models 131 and 133 in real time using the first delay time error signal 70 to update the additional path transfer function model 130. And generating a first reference noise signal 80 by applying the first reference signal 10 to the updated additional path transfer function model 130, the first error signal 60, and The convergence element is multiplied by the first reference noise signal 80 to generate a first adaptive adaptive filter 90, and the first adaptive adaptive filter 90 and the first adaptive filter 110 are added to the second adaptive filter 110. After the adaptive filter generating step and applying the first reference signal 10 to the second adaptive filter 110, the first addition And applying the reference signal to generate the first counter noise signal 30 by adding the signal 20. The delay time error signal generating step may generate a first delay time error signal 70 by high pass filtering the first error signal 60 and then comparing it with the first additional signal 20. In addition, the counter noise generating step may be generated by analyzing a frequency of the first reference signal 10 and selecting a frequency to be controlled among the frequencies of the analyzed first reference signal 10.
출력단계는 제1 반대소음신호(30)에 대한 제1 음향(40)을 출력한다.The output stage outputs the first sound 40 to the first counter noise signal 30.
또한, 감지단계는 제1 마이크로폰이 제2 샘플에 대한 제2 참조소음을 감지하고, 제2 마이크로폰이 제2 소음을 감지한다.In the sensing step, the first microphone detects the second reference noise for the second sample, and the second microphone detects the second noise.
부가신호 생성단계는 제1 마이크로폰에서 감지된 제2 참조소음에 의한 제2 참조신호(10)와 제2 마이크로폰에서 감지된 제2 소음에 의한 제2 오차신호(60)가 전송되면, 제2 부가신호(20)를 생성한다.The additional signal generating step may include: when the second reference signal 10 by the second reference noise detected by the first microphone and the second error signal 60 by the second noise detected by the second microphone are transmitted, the second additional signal is added. Generate signal 20.
반대소음신호 생성단계는 제2 참조신호(10), 제2 오차신호(60) 및 제2 부가신호(20)를 이용하여 제2 반대소음신호(30)를 생성한다. 구체적으로, 반대소음신호 생성단계는 지연시간 분석기(120)가 제2 부가신호(20)와 제2 오차신호(60)를 비교하여 제2 지연시간 오차신호(70)를 생성하는 지연시간 오차신호 생성단계, 부가경로 전달함수 모델(130)이 제2 지연시간 오차신호(70)를 이용하여 부가경로 전달함수 초기모델(131, 133)을 실시간으로 업데이트하여 업데이트된 부가 경로 전달함수 모델을 생성하고, 제2 참조신호(10)를 업데이트된 부가경로 전달함수 모델(130)에 적용하여 제2 참조소음신호(80)를 생성하는 참조소음신호 생성단계, 제2 오차신호(60) 및 수렴요소를 제2 참조소음신호(80)와 곱하여 제2 개선적응필터(90)를 생성하고, 제2 개선적응필터(90)와 제2 적응필터(110)를 더하여 제3 적응필터(110)를 생성하는 적응필터 생성단계 및 제2 참조신호(10)를 제3 적응필터(110)에 적용한 후, 제2 부가신호(20)를 더하여 제2 반대소음신호(30)를 생성하는 참조신호 적용단계를 포함한다.In the opposite noise generation step, the second opposite noise signal 30 is generated using the second reference signal 10, the second error signal 60, and the second additional signal 20. Specifically, in the opposite noise generation step, the delay time error signal in which the delay time analyzer 120 generates the second delay time error signal 70 by comparing the second additional signal 20 and the second error signal 60. In the generating step, the additional path transfer function model 130 updates the additional path transfer function initial models 131 and 133 in real time using the second delay time error signal 70 to generate an updated additional path transfer function model. The reference noise signal generating step of generating the second reference noise signal 80 by applying the second reference signal 10 to the updated additional path transfer function model 130, and the second error signal 60 and the convergent element The second improved adaptive filter 90 is generated by multiplying with the second reference noise signal 80, and the third adaptive filter 110 is generated by adding the second improved adaptive filter 90 and the second adaptive filter 110. After generating the adaptive filter and applying the second reference signal 10 to the third adaptive filter 110, the second additional signal In addition to the 20 second opposed it contains a reference signal applied to produce a noise signal (30).
출력단계는 제2 반대소음신호(30)에 대한 제2 음향(40)을 출력한다.The output step outputs a second sound 40 for the second counter noise signal 30.
그리고 감지단계는 제1 마이크로폰이 제n 샘플에 대한 제n 참조소음을 감지하고, 제2 마이크로폰이 제n 소음을 감지한다.In the sensing step, the first microphone detects the n th reference noise for the n th sample, and the second microphone detects the n th noise.
부가신호 생성단계는 제1 마이크로폰에서 감지된 제n 참조소음에 의한 제n 참조신호(10)와 제2 마이크로폰에서 감지된 제n 소음에 의한 제n 오차신호(60)가 전송되는 경우, 제n 부가신호(20)를 생성한다.The additional signal generating step is performed when the n th reference signal 10 due to the n th reference noise detected by the first microphone and the n th error signal 60 due to the n th noise detected by the second microphone are transmitted. The additional signal 20 is generated.
반대소음신호 생성단계는 제n 참조신호(10), 제n 오차신호(60) 및 제n 부가신호(20)를 이용하여 제n 반대소음신호(30)를 생성한다. 구체적으로, 반대소음신호 생성단계는 지연시간 분석기(120)가 제n 부가신호(20)와 제n 오차신호(60)를 비교하여 제n 지연시간 오차신호(70)를 생성하는 지연시간 오차신호 생성단계, 부가경로 전달함수 모델(130)이 제n 지연시간 오차신호(70)를 이용하여 부가경로 전달함수 초기모델(131, 133)을 실시간으로 업데이트하여 업데이트된 부가 경로 전달함수 모델을 생성하고, 제n 참조신호(10)를 업데이트된 부가경로 전달함수 모델(130)에 적용하여 제n 참조소음신호(80)를 생성하는 참조소음신호 생성단계, 제n 오차신호(60) 및 수렴요소를 제n 참조소음신호(80)와 곱하여 제n 개선적응필터(90)를 생성하고, 제n 개선적응필터(90)와 제n 적응필터(110)를 더하여 제n+1 적응필터(110)를 생성하는 적응필터 생성단계 및 제n 참조신호(10)를 제n+1 적응필터(110)에 적용한 후, 제n 부가신호(20)를 더하여 제n 반대소음신호(30)를 생성하는 참조신호 적용단계를 포함한다.In the opposite noise generating step, an nth opposite noise signal 30 is generated using the nth reference signal 10, the nth error signal 60, and the nth additional signal 20. Specifically, in the opposite noise generation step, the delay time error signal in which the delay time analyzer 120 generates the nth delay time error signal 70 by comparing the n th additional signal 20 and the n th error signal 60. In the generating step, the additional path transfer function model 130 updates the additional path transfer function initial models 131 and 133 in real time using the nth delay time error signal 70 to generate an updated additional path transfer function model. The reference noise signal generating step of generating the n-th reference noise signal 80 by applying the n-th reference signal 10 to the updated additional path transfer function model 130, and the n-th error signal 60 and the converging element The nth improvement adaptation filter 90 is generated by multiplying with the nth reference noise signal 80, and the n + 1th adaptation filter 110 is added by adding the nth improvement adaptation filter 90 and the nth adaptation filter 110. Applying the generated adaptive filter generation step and the nth reference signal 10 to the n + 1th adaptive filter 110, the nth addition And applying the reference signal to generate the nth counter noise signal 30 by adding the signal 20.
출력단계는 제n 반대소음신호(30)에 대한 제n 음향(40)을 출력한다.The output stage outputs an n th sound 40 to the n th opposite noise signal 30.
여기서, 제1 마이크로폰에서 감지된 제n 참조소음에 의한 제n 참조신호(10)가 업데이트된 부가경로 전달함수 모델(130)에 필터링되어 제n 참조소음신호(80)를 생성하고, 제n 참조소음신호(80)는 제n+1 적응필터(110)의 길이 L만한 버퍼에 순차적으로 저장이 되고, (따라서, 매 샘플마다 L길이의 벡터를 얻을 수 있다.) 그에 따른 L길이의 벡터는 제2 마이크로폰에서 감지된 제n 소음에 의한 제n 오차신호(60)와 곱하여진다. 이때, 곱한 결과에 수렴요소(step-size)라는 상수가 곱해지고, 이전 샘플에서 사용한 제n 적응필터(110)의 계수(L길이 벡터이기 때문에 계수의 값은 L개이다.)와 더하여 현재 샘플에서 사용할 적응필터(110)의 계수를 구한다. 이에 제n 참조신호(10)가 제n+1 적응필터(110)에 필터링된다.Here, the n th reference signal 10 by the n th reference noise detected by the first microphone is filtered by the updated additional path transfer function model 130 to generate the n th reference noise signal 80, and the n th reference noise. The noise signal 80 is sequentially stored in a buffer having a length L of the n + 1th adaptive filter 110 (thus, a vector of L length can be obtained for each sample). It is multiplied by the n-th error signal 60 caused by the n-th noise detected by the second microphone. In this case, the result of the multiplication is multiplied by a constant called a step-size, and the coefficient of the nth adaptive filter 110 used in the previous sample (the value of the coefficient is L because it is an L length vector) is added to the current sample. The coefficient of the adaptive filter 110 to be used is obtained. Accordingly, the n th reference signal 10 is filtered by the n + 1 th adaptive filter 110.
또한, 적응필터 생성단계에서 제2 적응필터(110), 제3 적응필터(110), …, 제n+1 적응필터(110)를 생성하는 것은 제2 오차신호(60), …, 제n 오차신호(60)의 제곱 값이 최소화되는 방향으로 생성시키는 것일 수 있다.In addition, in the adaptive filter generation step, the second adaptive filter 110, the third adaptive filter 110,. The generation of the n + 1th adaptive filter 110 may include the second error signal 60,. The n th error signal 60 may be generated in a direction in which the square value of the n th error signal 60 is minimized.
그리고 제1 마이크로폰이 제1 참조소음을 감지하고, 제2 마이크로폰이 제1 소음을 감지하는 단계 이전에는, 백색잡음신호를 생성하고, 생성된 백색잡음신호에 대한 음향을 출력하는 단계 및 제2 마이크로폰에서 감지된 음향에 의한 전달신호와 백색잡음신호를 이용하여 부가경로 전달함수 초기모델을 생성하는 단계를 더 포함할 수 있다.And before the step of the first microphone detecting the first reference noise and the second microphone detecting the first noise, generating a white noise signal, outputting a sound for the generated white noise signal, and the second microphone. The method may further include generating an additional path transfer function initial model by using the transfer signal and the white noise signal detected by the sound.
이와 같이, 실시 형태에 따른 소음제어방법은 제1 부가신호(20), 제2 부가신호(20), …, 제n 부가신호(20)를 생성하여 제1 지연시간 오차신호(70), 제2 지연시간 오차신호(70), …, 제n 지연시간 오차신호(70)를 생성하기 때문에, 주변의 온도나 압력 등이 변하여 소리의 속도가 바뀌는 불안정한 부가경로 전달함수를 가지는 환경에서도 소음을 제어할 수 있고, 소음을 완전히 제거할 수 있는 이점이 있다.As described above, in the noise control method according to the embodiment, the first additional signal 20, the second additional signal 20,... To generate the n-th additional signal 20 to generate the first delay time error signal 70, the second delay time error signal 70,. Since the nth delay time error signal 70 is generated, the noise can be controlled even in an environment having an unstable additional path transfer function in which the ambient temperature or pressure changes and the speed of the sound changes, thereby completely eliminating the noise. There is an advantage to that.
또한, 실시 형태에 따른 소음제어방법은 부가경로 전달함수 초기모델(131, 133)이 제1 지연시간 오차신호(70), 제2 지연시간 오차신호(70), …, 제n 지연시간 오차신호(70)에 의해 실시간으로 업데이트되기 때문에, 온도나 압력에 따라 부가경로 전달함수의 지연시간이 주파수 별로 선형적으로 변하는 어떠한 환경에서도 소음을 제어할 수 있는 이점이 있다.In addition, in the noise control method according to the embodiment, the additional path transfer function initial models 131 and 133 may include the first delay time error signal 70, the second delay time error signal 70,. Since it is updated in real time by the nth delay time error signal 70, there is an advantage that the noise can be controlled in any environment where the delay time of the additional path transfer function varies linearly with frequency according to temperature or pressure.
또한, 실시 형태에 따른 소음제어방법은 도 11에서 설명한 부가경로 전달함수 초기모델(131, 133)은 도 10에서 설명한 내용과 동일한 방법으로 생성되기 때문에, 출력된 음향에 의한 전달신호만으로도 부가경로 전달함수에 따른 부가경로 전달함수 초기모델(131, 133)을 간단하게 생성할 수 있는 이점이 있다.In addition, in the noise control method according to the embodiment, since the additional path transfer function initial models 131 and 133 described with reference to FIG. 11 are generated by the same method as described with reference to FIG. The additional path transfer function initial models 131 and 133 according to the function can be easily generated.
또한, 실시 형태에 따른 소음제어방법은 제1 오차신호(60), 제2 오차신호(60), …, 제n 오차신호(60)를 하이패스 필터링한 후, 제1 부가신호(20), 제2 부가신호(20), …, 제n 부가신호(20)와 비교하여 제1 지연시간 오차신호(70), 제2 지연시간 오차신호(70), …, 제n 지연시간 오차신호(70)를 생성하기 때문에, 제1 오차신호(60), 제2 오차신호(60), …, 제n 오차신호(60)에 포함된 가청주파수 대역이 필터링되어 제1 오차신호(60), 제2 오차신호(60), …, 제n 오차신호(60)에 포함된 초음파 대역만으로 보다 더 간단하게 부가경로 전달함수의 지연시간의 변화를 계산할 수 있는 이점이 있다.In addition, in the noise control method according to the embodiment, the first error signal 60, the second error signal 60,... After the high pass filtering the n-th error signal 60, the first additional signal 20, the second additional signal 20,. , Compared with the n th additional signal 20, the first delay time error signal 70, the second delay time error signal 70,. , Since the nth delay time error signal 70 is generated, the first error signal 60, the second error signal 60,. , The audio frequency band included in the n-th error signal 60 is filtered so that the first error signal 60, the second error signal 60,. In addition, there is an advantage that the change in the delay time of the additional path transfer function can be calculated more simply with only the ultrasonic band included in the n-th error signal 60.
또한, 실시 형태에 따른 소음제어방법은 제1 참조신호(10), 제2 참조신호(10), …, 제n 참조신호(10)의 주파수를 분석하고, 분석된 제1 참조신호(10), 제2 참조신호(10), …, 제n 참조신호(10)의 주파수 중 제어하고자 하는 주파수를 선택하여 제1 반대소음신호(30), 제2 반대소음신호(30), …, 제n 반대소음신호(30)를 생성하기 때문에, 원하는 주파수 소음만 저감하는 것이 가능하며, 제n 부가신호(20)를 이용하여 지연시간의 변화를 계산하는 과정이 간단해질 수 있는 이점이 있다.In addition, in the noise control method according to the embodiment, the first reference signal 10, the second reference signal 10,... , The frequency of the n th reference signal 10 is analyzed, and the analyzed first reference signal 10, the second reference signal 10,. , By selecting a frequency to be controlled among the frequencies of the n th reference signal 10, the first reverse noise signal 30, the second reverse noise signal 30,... Since the nth counter noise signal 30 is generated, it is possible to reduce only desired frequency noise, and the process of calculating a change in delay time using the nth additional signal 20 can be simplified. .
그리고 실시 형태에 따른 소음제어방법은 가청주파수 외의 주파수 신호를 제1 부가신호(20), 제2 부가신호(20), …, 제n 부가신호(20)로 이용하기 때문에, 가청주파수의 신호를 제1 부가신호(20), 제2 부가신호(20), …, 제n 부가신호(20)로 이용할 때 발생하는 추가적인 소음을 발생하지 않고 지연시간의 변화를 감지하면서 동시에 이를 보상할 수 있는 이점이 있다.In the noise control method according to the embodiment, the first additional signal 20, the second additional signal 20,... Since the n th additional signal 20 is used, the audible frequency signal is converted into a first additional signal 20, a second additional signal 20,... For example, there is an advantage in that it is possible to compensate for this while simultaneously detecting a change in delay time without generating additional noise generated when using the n th additional signal 20.
이와 같이, 실시 형태에 따른 소음제어방법을 이용하면 주변의 온도나 압력이 크게 변할 수 있는 환경에서도 효과적으로 소음을 제어할 수 있다. 또한, 시스템의 지연시간이 크게 변하지 않는 환경에서는 종래의 방식 그대로 알고리즘이 적용될 것이며, 크게 변하게 된다면 그에 따른 위상오차를 보상하여 안정적으로 소음을 저감할 수 있을 것이다.In this way, the noise control method according to the embodiment can effectively control the noise even in an environment where the ambient temperature or pressure can be greatly changed. In addition, in an environment in which the delay time of the system does not change significantly, the algorithm will be applied as it is, and if the change is large, the phase error will be compensated accordingly and the noise will be stably reduced.
이상에서는 도면 및 실시 형태를 참조하여 설명하였지만, 해당 기술 분야의 숙련된 당업자는 하기의 특허청구범위에 기재된 본 출원의 기술적 사상으로부터 벗어나지 않는 범위 내에서 본 출원에 개시된 실시예들은 다양하게 수정 및 변경시킬 수 있음을 이해할 수 있을 것이다. 이상에서 실시예들에 설명된 특징, 구조, 효과 등은 본 발명의 적어도 하나의 실시예에 포함되며, 반드시 하나의 실시예에만 한정되는 것은 아니다. 나아가, 각 실시예에서 예시된 특징, 구조, 효과 등은 실시예들이 속하는 분야의 통상의 지식을 가지는 자에 의해 다른 실시예들에 대해서도 조합 또는 변형되어 실시 가능하다. 따라서 이러한 조합과 변형에 관계된 내용들은 본 발명의 범위에 포함되는 것으로 해석되어야 할 것이다.Although described above with reference to the drawings and embodiments, those skilled in the art will be variously modified and changed in the embodiments disclosed herein without departing from the spirit of the present application described in the claims I can understand that you can. Features, structures, effects, and the like described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, contents related to such combinations and modifications should be construed as being included in the scope of the present invention.
[부호의 설명][Description of the code]
100: 능동소음제어 알고리즘100: active noise control algorithm
110: 적응필터110: adaptive filter
120: 지연시간 분석기120: latency analyzer
130: 부가경로 전달함수 모델130: additional path transfer function model
140: 업데이트 알고리즘140: update algorithm
200: 부가경로 전달함수부200: additional path transfer function
Claims (12)
- 참조신호를 입력받아 제1 반대소음신호를 생성하고, 상기 제1 반대소음신호에 대한 제1 음향을 출력하는 제1 출력단계;A first output step of receiving a reference signal to generate a first opposite noise signal and outputting a first sound with respect to the first opposite noise signal;상기 제1 음향이 출력되는 동안 제1 소음을 감지하는 제1 감지단계;A first sensing step of sensing a first noise while the first sound is output;상기 제1 소음이 감지되는 경우, 상기 제1 반대소음신호에 부가신호를 더하여 제2 반대소음신호를 생성하고, 상기 제2 반대소음신호에 대한 제2 음향을 출력하는 제2 출력단계;A second output step of generating a second counter noise signal by adding an additional signal to the first counter noise signal when the first noise is detected, and outputting a second sound with respect to the second counter noise signal;상기 제2 음향이 출력되는 동안 제2 소음을 감지하는 제2 감지단계; 및A second sensing step of sensing a second noise while the second sound is output; And상기 제2 소음이 감지되는 경우, 상기 부가신호와 상기 제2 소음에 의한 신호를 비교하여 지연시간 오차신호를 생성하고, 상기 지연시간 오차신호를 이용하여 제3 반대소음신호를 생성하고, 상기 제3 반대소음신호에 대한 제3 음향을 출력하는 제3 출력단계;를 포함하는, 소음제어방법.When the second noise is detected, a delay time error signal is generated by comparing the additional signal with a signal caused by the second noise, and a third counter noise signal is generated by using the delay time error signal. And a third output step of outputting a third sound with respect to the opposite noise signal.
- 제1항에 있어서,The method of claim 1,상기 제1 출력단계는, 상기 참조신호를 제1 적응필터에 적용하여 상기 제1 반대소음신호를 생성하고,In the first output step, the reference signal is applied to a first adaptive filter to generate the first counter noise signal.상기 제3 출력단계는, 상기 지연시간 오차신호에 의해 업데이트된 부가경로 전달함수 모델에 상기 참조신호를 적용하여 참조소음신호를 생성하고, 상기 참조소음신호와 상기 제2 소음에 의한 신호를 곱하여 생성된 개선적응필터와 상기 제1 적응필터를 더하여 제2 적응필터를 생성하고, 상기 참조신호를 상기 제2 적응필터에 적용하여 상기 제3 반대소음신호를 생성하는, 소음제어방법.In the third output step, the reference noise signal is generated by applying the reference signal to the additional path transfer function model updated by the delay time error signal, and is generated by multiplying the reference noise signal by the signal caused by the second noise. Generating a second adaptive filter by adding the improved adaptive filter and the first adaptive filter, and generating the third counter noise signal by applying the reference signal to the second adaptive filter.
- 제2항에 있어서,The method of claim 2,상기 제1 출력단계 이전에,Before the first output step,백색잡음신호를 생성하고, 상기 백색잡음신호에 대한 제4 음향을 출력하는 단계; 및Generating a white noise signal and outputting a fourth sound with respect to the white noise signal; And상기 제4 음향이 출력되는 동안 감지된 제5 음향에 의한 전달신호와 상기 백색잡음신호를 이용하여 상기 부가경로 전달함수의 초기모델을 생성하는 단계;를 더 포함하는, 소음제어방법.And generating an initial model of the additional path transfer function by using the white noise signal and the transmission signal of the fifth sound detected while the fourth sound is output.
- 제1항에 있어서,The method of claim 1,상기 제3 출력단계는, 상기 제2 소음에 의한 신호를 하이패스 필터링한 후, 상기 부가신호와 비교하여 상기 지연시간 오차신호를 생성하는, 소음제어방법.The third output step, after the high-pass filtering the signal caused by the second noise, and compared with the additional signal to generate the delay time error signal, noise control method.
- 제1항에 있어서,The method of claim 1,상기 제1 출력단계는, 상기 참조신호의 주파수를 분석하고, 상기 참조신호의 주파수 중 제어하고자 하는 주파수를 선택하여 상기 제1 반대소음신호를 생성하는, 소음제어방법.And outputting the first counter noise signal by analyzing a frequency of the reference signal and selecting a frequency to be controlled among the frequencies of the reference signal.
- 제1항에 있어서,The method of claim 1,상기 부가신호는 가청주파수 외의 주파수 신호인, 소음제어방법.And said additional signal is a frequency signal other than an audible frequency.
- 제1 마이크로폰이 제1 샘플, 제2 샘플, …, 제n 샘플에 대한 제1 참조소음, 제2 참조소음, …, 제n 참조소음을 감지하고, 제2 마이크로폰이 제1 소음, 제2 소음, …, 제n 소음을 감지하는 감지단계;The first microphone comprises a first sample, a second sample,... , First reference noise for the n th sample, second reference noise,... , N-th reference noise, and the second microphone detects the first noise, the second noise,... A sensing step of detecting an n-th noise;상기 제1 마이크로폰에서 감지된 상기 제1 참조소음, 상기 제2 참조소음, …, 상기 제n 참조소음에 의한 제1 참조신호, 제2 참조신호, …, 제n 참조신호와 상기 제2 마이크로폰에서 감지된 상기 제1 소음, 상기 제2 소음, …, 상기 제n 소음에 의한 제1 오차신호, 제2 오차신호, …, 제n 오차신호가 전송되는 경우, 제1 부가신호, 제2 부가신호, …, 제n 부가신호를 생성하는 부가신호 생성단계;The first reference noise sensed by the first microphone, the second reference noise,... , A first reference signal, a second reference signal by the nth reference noise,... , The first noise detected by the n-th reference signal and the second microphone, the second noise,... , The first error signal, the second error signal due to the n-th noise,... , When the nth error signal is transmitted, the first additional signal, the second additional signal,. An additional signal generating step of generating an nth additional signal;상기 제1 참조신호, 상기 제2 참조신호, …, 상기 제n 참조신호, 상기 제1 오차신호, 상기 제2 오차신호, …, 상기 제n 오차신호 및 상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호를 이용하여 제1 반대소음신호, 제2 반대소음신호, …, 제n 반대소음신호를 생성하는 반대소음신호 생성단계; 및The first reference signal, the second reference signal,... The n th reference signal, the first error signal, the second error signal,... , The nth error signal, the first additional signal, the second additional signal,... A first opposite noise signal, a second opposite noise signal,... A counter noise signal generating step of generating an n-th counter noise signal; And상기 제1 반대소음신호, 상기 제2 반대소음신호, …, 상기 제n 반대소음신호와 상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호를 더하여 상기 제1 반대소음신호에 대한 제1 음향, 상기 제2 반대소음신호에 대한 제2 음향, …, 상기 제n 반대소음신호에 대한 제n 음향을 출력하는 출력단계;로 이루어지는, 소음제어방법.The first counter noise signal, the second counter noise signal,... The nth reverse noise signal, the first additional signal, the second additional signal,... , The first sound of the first counter noise signal, the second sound of the second counter noise signal by adding the n-th additional signal; And an output step of outputting an n-th sound for the n-th counter noise signal.
- 제7항에 있어서,The method of claim 7, wherein상기 반대소음신호 생성단계는,The opposite noise signal generating step,상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호와 상기 제1 오차신호, 상기 제2 오차신호, …, 상기 제n 오차신호를 비교하여 제1 지연시간 오차신호, 제2 지연시간 오차신호, …, 제n 지연시간 오차신호를 생성하는 지연시간 오차신호 생성단계;The first additional signal, the second additional signal,... The nth additional signal, the first error signal, the second error signal,... Comparing the n-th error signal to obtain a first delay time error signal, a second delay time error signal,. A delay time error signal generating step of generating an nth delay time error signal;상기 제1 지연시간 오차신호, 상기 제2 지연시간 오차신호, …, 상기 제n 지연시간 오차신호를 이용하여 부가경로 전달함수 모델의 부가경로 전달함수 초기모델을 실시간으로 업데이트하여 업데이트된 부가경로 전달함수 모델을 생성하고, 상기 제1 참조신호, 상기 제2 참조신호, …, 상기 제n 참조신호를 상기 업데이트된 부가경로 전달함수 모델에 적용하여 제1 참조소음신호, 제2 참조소음신호, …, 제n 참조소음신호를 생성하는 참조소음신호 생성단계;The first delay time error signal, the second delay time error signal,... Generating an updated additional path transfer function model by updating an initial model of the additional path transfer function of the additional path transfer function model in real time using the n th delay time error signal, and generating the first reference signal and the second reference signal ,… Applying the n th reference signal to the updated additional path transfer function model to generate a first reference noise signal, a second reference noise signal,... A reference noise signal generating step of generating an n-th reference noise signal;상기 제1 오차신호, 상기 제2 오차신호, …, 상기 제n 오차신호를 상기 제1 참조소음신호, 상기 제2 참조소음신호, …, 상기 제n 참조소음신호와 곱하여 제1 개선적응필터, 제2 개선적응필터, …, 제n 개선적응필터를 생성하고, 상기 제1 개선적응필터, 상기 제2 개선적응필터, …, 상기 제n 개선적응필터와 제1 적응필터, 제2 적응필터, …, 제n 적응필터를 더하여 제2 적응필터, 제3 적응필터, …, 제n+1 적응필터를 생성하는 적응필터 생성단계; 및The first error signal, the second error signal,... The n th error signal may be converted into the first reference noise signal, the second reference noise signal,. A first improvement adaptation filter, a second improvement adaptation filter,. Generate an nth improvement adaptation filter, the first improvement adaptation filter, the second improvement adaptation filter,. , The nth improvement adaptive filter, the first adaptive filter, the second adaptive filter,. The second adaptive filter, the third adaptive filter,. An adaptive filter generating step of generating an n + 1th adaptive filter; And상기 제1 참조신호, 상기 제2 참조신호, …, 상기 제n 참조신호를 상기 제2 적응필터, 상기 제3 적응필터, …, 상기 제n+1 적응필터에 적용한 후, 제1 부가신호, 제2 부가신호, …, 제n 부가신호를 더하여 상기 제1 반대소음신호, 상기 제2 반대소음신호, …, 상기 제n 반대소음신호를 생성하는 참조신호 적용단계;를 포함하고,The first reference signal, the second reference signal,... The n th reference signal is applied to the second adaptive filter, the third adaptive filter,. , After applying to the n + 1th adaptive filter, a first additional signal, a second additional signal,. , By adding the n-th additional signal, the first opposite noise signal, the second opposite noise signal,... And a reference signal applying step of generating the nth counter noise signal.상기 적응필터 생성단계는, 상기 제2 오차신호, …, 상기 제n 오차신호의 제곱 값이 최소화되는 방향으로 상기 제2 적응필터, 상기 제3 적응필터, …, 상기 제n+1 적응필터를 생성하는, 소음제어방법.The adaptive filter generating step may include the second error signal,... , The second adaptive filter, the third adaptive filter,... In a direction in which the square of the n-th error signal is minimized. And generating the n + 1th adaptive filter.
- 제8항에 있어서,The method of claim 8,상기 감지 단계 이전에,Before the detection step,백색잡음신호를 생성하고, 상기 백색잡음신호에 대한 음향을 출력하는 단계; 및Generating a white noise signal and outputting a sound for the white noise signal; And상기 제2 마이크로폰에서 감지된 상기 음향에 의한 전달신호와 상기 백색잡음신호를 이용하여 상기 부가경로 전달함수의 초기모델을 생성하는 단계;를 더 포함하는, 소음제어방법.And generating an initial model of the additional path transfer function by using the white noise signal and the transmission signal of the sound sensed by the second microphone.
- 제8항에 있어서,The method of claim 8,상기 지연시간 오차신호 생성단계는,The delay time error signal generation step,상기 제1 오차신호, 상기 제2 오차신호, …, 상기 제n 오차신호를 하이패스 필터링한 후, 상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호와 비교하여 상기 제1 지연시간 오차신호, 상기 제2 지연시간 오차신호, …, 상기 제n 지연시간 오차신호를 생성하는, 소음제어방법.The first error signal, the second error signal,... After the high pass filtering the n-th error signal, the first additional signal, the second additional signal,. The first delay time error signal, the second delay time error signal,... And generating the nth delay time error signal.
- 제7항 또는 제8항에 있어서,The method according to claim 7 or 8,상기 반대소음신호 생성단계는,The opposite noise signal generating step,상기 제1 참조신호, 상기 제2 참조신호, …, 상기 제n 참조신호의 주파수를 분석하고,The first reference signal, the second reference signal,... Analyze the frequency of the n-th reference signal,상기 분석된 제1 참조신호, 제2 참조신호, …, 제n 참조신호의 주파수 중 제어하고자 하는 주파수를 선택하여 상기 제1 반대소음신호, 상기 제2 반대소음신호, …, 상기 제n 반대소음신호를 생성하는 단계;를 포함하는, 소음제어방법.The analyzed first reference signal, second reference signal,... Selects a frequency to be controlled among the frequencies of the n th reference signal to select the first counter noise signal, the second counter noise signal,... And generating the n th counter noise signal.
- 제7항 또는 제8항에 있어서,The method according to claim 7 or 8,상기 제1 부가신호, 상기 제2 부가신호, …, 상기 제n 부가신호는 가청주파수 외의 주파수 신호인, 소음제어방법. The first additional signal, the second additional signal,... And the nth additional signal is a frequency signal other than an audible frequency.
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