CN115171719B - System, method and computer equipment for determining drift frequency of low-speed prompt tone of electric automobile - Google Patents
System, method and computer equipment for determining drift frequency of low-speed prompt tone of electric automobile Download PDFInfo
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Abstract
A system, a method and computer equipment for determining the drift frequency of low-speed prompt tones of an electric automobile belong to the technical field of active sounding and solve the problem of low accuracy of acquiring the drift frequency in the prior art. The system of the invention comprises: the device comprises an electric automobile working condition testing module, a uniform speed working condition module, a uniform acceleration working condition module and a drift frequency determining module; the electric automobile working condition testing module is used for placing an electric automobile in the silencing chamber, and the microphone is arranged around the electric automobile; the constant-speed sound module comprises a constant-speed sound acquisition unit and a constant-speed sound signal processing unit; the uniform acceleration working condition module comprises a uniform acceleration sound acquisition unit and a uniform acceleration sound signal processing unit; and the drift frequency determining module is used for determining the drift frequency of the low-speed prompt tone of the electric automobile according to the average self-power spectrum and the sound spectrum. The invention is suitable for testing and analyzing the low-speed prompt tone of the electric automobile.
Description
Technical Field
The application relates to the field of active sounding of electric automobiles, in particular to a system, a method and computer equipment for determining the drift frequency of low-speed prompt tones of electric automobiles.
Background
When an electric vehicle (a pure electric vehicle, a hybrid electric vehicle, a fuel cell vehicle and the like) runs at a low speed in a pure electric mode, the average noise outside the vehicle is obviously reduced compared with that of a traditional diesel vehicle, so that other users on the road, including pedestrians, bicycles and the like, especially blind people and people with vision disorder cannot easily perceive the approach of the vehicle, and traffic accidents are easy to occur.
The electric automobile low speed prompt tone (GB/T37153-2018) prescribes the requirements and test methods of the vehicle speed range, sound level limit value, frequency requirement, sound type, pause switch and the like of the electric automobile low speed running prompt tone (hereinafter referred to as 'prompt tone') work. The standard is suitable for the pure electric vehicles of M 1 and N 1, the hybrid electric vehicle with the pure electric driving mode and the fuel cell electric vehicle.
The current national standard GB/T37153-2018 'electric automobile Low speed prompt tone' requires testing the frequency shift of the electric automobile Low speed prompt tone and calculating the frequency shift rate changing along with the speed of the automobile, and the national standard provides the testing and calculating method of the frequency shift rate, which is a method commonly used in the industry. The specific steps for determining the drift frequency are as follows:
(1) As shown in FIGS. 1-4, the sound signals at constant speeds of 5km/h, 10km/h, 15km/h, and 20km/h were tested, respectively.
(2) The average self-power spectrum is calculated separately for each sound signal at each speed.
(3) A certain frequency peak is determined on the self-power spectrum of the corresponding sound signal at a speed of 5 km/h.
(4) And (3) finding out the frequency value corresponding to the frequency peak value on the self-power spectrums of 10km/h, 15km/h and 20km/h respectively by a visual comparison method.
The method has the defects that when the sound frequency is complex, and a plurality of different peaks appear on the self-power spectrum, the peaks can interfere with each other, at the moment, the frequency peaks under different vehicle speeds are difficult to accurately correspond by the self-power spectrum comparison method, so that the frequency peak selection is wrong, the frequency shift rate calculation result is wrong, the pedestrian prompt tone which does not accord with the national standard is misjudged to accord with the standard, or the pedestrian prompt tone which does not accord with the national standard is misjudged to not accord with the national standard, namely the judgment is wrong.
The input and output of each automobile manufacturer in the field of electric automobiles are larger and larger in China, so that misjudgment on the frequency shift of low-speed pedestrian prompt tones is avoided, the accuracy of identifying drift frequency is very necessary, and even the accuracy can reach hundred percent. The method for visually comparing the average power spectrum in the process of determining the drift frequency in the prior art has the defects that the method is quite inaudible, when a plurality of peaks interfere with each other, the drift frequency is difficult to determine correctly, once errors occur, the prompting sound of the electric automobile does not meet the regulation requirements, the possibility of accidents is necessarily increased, further, if accidents occur, irrecoverable cost is caused, the consequence is quite serious, the accuracy of prompting sound early warning of the electric automobile under the low-speed working condition is quite necessary, the key of prompting sound is the drift frequency, and the technical problem that how to acquire the high-precision low-speed prompting sound drift frequency of the electric automobile is needed to be solved is urgent.
Disclosure of Invention
The invention aims to solve the problem of low accuracy in acquiring drift frequency in the prior art, and provides a system, a method and computer equipment for determining the drift frequency of low-speed prompt tones of an electric automobile.
The invention is realized through the following technical scheme, and in one aspect, the invention provides a system for determining the drift frequency of low-speed prompt tones of an electric automobile, which comprises: the device comprises an electric automobile working condition testing module, a uniform speed working condition module, a uniform acceleration working condition module and a drift frequency determining module;
The electric automobile working condition testing module comprises a microphone and a silencing chamber, the silencing chamber is used for accommodating an electric automobile to be detected and the microphone,
The microphone is used for acquiring sound signals generated by the electric automobile to be detected;
the constant-speed working condition module comprises a constant-speed sound acquisition unit and a constant-speed sound signal processing unit;
The constant-speed sound collection unit is used for collecting sound signals of the electric automobile under a constant-speed working condition;
the constant-speed sound signal processing unit is used for processing sound signals of the electric automobile under a constant-speed working condition to obtain an average self-power spectrum;
the uniform acceleration working condition module comprises a uniform acceleration sound acquisition unit and a uniform acceleration sound signal processing unit;
The uniform acceleration sound collection unit is used for collecting sound signals of the electric automobile under a uniform acceleration working condition;
the uniform acceleration sound signal processing unit is used for processing sound signals of the electric automobile under a uniform acceleration working condition to obtain a sound spectrum;
The drift frequency determining module is used for determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
Further, the silencing chamber is a semi-silencing chamber, and the shortest distance between the front end of the wedge in the silencing chamber and the electric automobile to be detected in the front, back, left and right directions is greater than 1m.
Further, the microphone is arranged on the front end face of the electric automobile to be detected.
Further, the drift frequency determining module comprises a spectrum acquisition unit, a drift frequency preliminary determining unit and a drift frequency final determining unit;
The spectrum acquisition unit is used for receiving the average self-power spectrum and the sound spectrum sent by the uniform acceleration sound acquisition unit and the uniform acceleration sound signal processing unit;
the drift frequency preliminary determination unit is used for selecting an order line according to the sound spectrum;
According to the order line, determining a frequency initial value under a uniform-speed working condition;
the drift frequency final determining unit is used for determining the drift frequency of the electric automobile according to the frequency initial value and the average self-power spectrum under the uniform speed working condition, and specifically comprises the following steps:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value and the range value under the uniform-speed working condition, and determining the highest peak point as the drift frequency of the electric automobile.
In a second aspect, the present invention provides a method for determining a drift frequency of a low-speed alert sound of an electric vehicle, the method comprising:
step 1, acquiring sound signals of an electric automobile under a uniform-speed working condition;
Acquiring sound signals of the electric automobile under a uniform acceleration working condition;
step 2, processing the sound signal under the uniform-speed working condition to obtain an average self-power spectrum;
Processing the sound signal of the electric automobile under the uniform acceleration working condition to obtain a sound spectrum;
And step 3, determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
Further, the step 3 specifically includes:
step 3.1, selecting an order line according to the sound spectrum;
Step 3.2, determining a frequency initial value under a uniform-speed working condition according to the order line;
Step 3.3, determining the drift frequency of the electric automobile according to the frequency initial value under the uniform-speed working condition and the average self-power spectrum, wherein the drift frequency is specifically as follows:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value under the uniform speed working condition and the range value, and determining the highest peak point as the drift frequency of the electric automobile.
Further, the step 3.1 specifically includes:
Step 3.1.1, setting a sound pressure level threshold;
And 3.1.2, selecting an order line with a sound pressure level greater than the sound pressure level threshold according to the sound spectrum.
Further, the sound spectrum takes the vehicle speed as an ordinate, the frequency as an abscissa, the frequency unit as Hz, and the gray scale represents the sound pressure level.
Further, the processing the sound signal under the uniform-speed working condition to obtain an average self-power spectrum specifically includes: and processing the sound signal under the uniform-speed working condition by utilizing a hanning window and at least 66.6% overlapping average to obtain an average self-power spectrum.
In a third aspect, the present invention provides a computer device comprising a memory and a processor, the memory having stored therein a computer program which when executed by the processor performs the steps of a method of determining a low speed alert tone drift frequency of an electric vehicle as described above.
The invention has the beneficial effects that:
The invention provides a system and a method for determining the drift frequency of low-speed prompt tones of an electric vehicle, which can determine the drift frequency of the low-speed prompt tones of the electric vehicle more quickly and accurately.
In the low-speed range of the electric vehicle, the invention generates a sound spectrum by testing sound signals of the vehicle in the whole process of uniform acceleration, can track the drifting process of each frequency peak value according to the order line on the sound spectrum, and then combines the average self-power spectrum under the uniform-speed working condition to determine drifting frequency.
Compared with the prior art, the invention can more intuitively observe all drift frequencies, and the accuracy of identifying the frequency of drift at each vehicle speed can reach nearly 100 percent, thereby providing very powerful safety guarantee for the electric vehicle running at low speed.
The invention is suitable for testing and analyzing the low-speed prompt tone of the electric automobile.
Drawings
In order to more clearly illustrate the technical solution of the present application, the drawings that are needed in the embodiments will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 is a graph of the self-power spectrum (frequency on the abscissa, hz, amplitude on the ordinate, dB (A)) at a vehicle speed of 5 km/h;
FIG. 2 is a graph of the self-power spectrum (frequency in Hz on the abscissa, amplitude in dB (A) on the ordinate) at a vehicle speed of 10 km/h;
FIG. 3 is a graph of the self-power spectrum (frequency in Hz on the abscissa, amplitude in dB (A) on the ordinate) at a vehicle speed of 15 km/h;
FIG. 4 is a graph of the self-power spectrum (frequency in Hz on the abscissa, amplitude in dB (A) on the ordinate) for a vehicle speed of 20 km/h;
FIG. 5 is a schematic diagram of an electric vehicle condition test module according to the present invention;
FIG. 6 is a sound spectrum of the uniform acceleration condition of the present invention;
FIG. 7 is a schematic diagram of accurate determination of the drift frequency of sound at a speed of 5km/h from sound spectrum to self-power spectrum;
FIG. 8 is a schematic diagram of accurate determination of the drift frequency of sound at a speed of 10km/h from sound spectrum to self-power spectrum;
FIG. 9 is a schematic diagram of accurate determination of the drift frequency of sound at 15km/h speed from sound spectrum to self-power spectrum;
FIG. 10 is a schematic diagram of accurate determination of the drift frequency of sound at 20km/h speed from sound spectrum to self-power spectrum;
FIG. 11 is a plot of the corresponding frequency at the highest peak determined on the self-power spectrum (frequency on the abscissa, hz, amplitude on the ordinate, dB (A));
FIG. 12 is a schematic flow chart of the method of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and intended to illustrate the present invention and should not be construed as limiting the invention.
The first embodiment is an embodiment of the system for determining the low-speed prompt tone drift frequency of the electric automobile.
The system comprises: the device comprises an electric automobile working condition testing module, a uniform speed working condition module, a uniform acceleration working condition module and a drift frequency determining module;
FIG. 5 is a schematic diagram of an electric vehicle working condition testing module according to the present invention, as shown in FIG. 5, wherein the electric vehicle working condition testing module includes a microphone and a sound damping chamber, an electric vehicle is placed in the sound damping chamber, and the microphone is disposed around the electric vehicle;
The electric automobile working condition testing module comprises a microphone and a silencing chamber, the silencing chamber is used for accommodating an electric automobile to be detected and the microphone,
The microphone is used for acquiring sound signals generated by the electric automobile to be detected;
the constant-speed working condition module comprises a constant-speed sound acquisition unit and a constant-speed sound signal processing unit;
The constant-speed sound collection unit is used for collecting sound signals of the electric automobile under a constant-speed working condition;
the constant-speed sound signal processing unit is used for processing sound signals of the electric automobile under a constant-speed working condition to obtain an average self-power spectrum;
the uniform acceleration working condition module comprises a uniform acceleration sound acquisition unit and a uniform acceleration sound signal processing unit;
The uniform acceleration sound collection unit is used for collecting sound signals of the electric automobile under a uniform acceleration working condition;
the uniform acceleration sound signal processing unit is used for processing sound signals of the electric automobile under a uniform acceleration working condition to obtain a sound spectrum;
The drift frequency determining module is used for determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
In this embodiment, in order to obtain sound signal data of the electric automobile under each working condition, an electric automobile working condition test module is designed, so that effective collection of the sound signal can be realized, and an accurate data basis is provided for subsequent determination of drift frequency.
The system of the embodiment not only can acquire the sound signal of the electric automobile under the constant-speed working condition and process the sound signal under the constant-speed working condition, but also can record the continuous sound signal of the automobile in the whole acceleration process and can acquire the continuous sound frequency spectrum. The sound data of the uniform acceleration process is generated into a sound spectrum by taking time or vehicle speed (the uniform acceleration working condition, the corresponding relationship between the time and the vehicle speed) as an ordinate and frequency (Hz) as an abscissa, wherein the gray scale represents the sound pressure level. The continuous bright line with larger sound pressure level, namely the order line, can be found through the sound spectrum, and the order line is generated due to peak frequency drift, so that the drift frequency at each vehicle speed can be roughly determined along the order line;
Then, according to the roughly determined drift frequency of each vehicle speed, a corresponding peak point is selected from the average self-power spectrum under the uniform speed working condition, so that the accurate drift frequency can be obtained, and inaccuracy caused by the fact that the average self-power spectrum has a plurality of peaks and the real drift frequency cannot be accurately determined can be solved.
In a second embodiment, the system for determining a drift frequency of a low-speed alert sound of an electric vehicle according to the first embodiment is further defined, in the second embodiment, the muffling chamber is further defined,
The method specifically comprises the following steps:
the silencing chamber is a semi-silencing chamber, and the shortest distance between the front end of the wedge in the silencing chamber and the electric automobile to be detected in the front, back, left and right directions is greater than 1m.
In this embodiment, a specific design of the muffling chamber is provided, including the type of muffling chamber in which the electric vehicle is designed.
The sound-damping chamber is selected from a half-damping chamber, and can provide a standard test environment according to absorption and reflection principles in sound transmission, so that the influence of uncertainty of the sound test environment on a test result is eliminated, and the consistency of the test result is higher;
The shortest distance between the front end of the wedge in the anechoic chamber and the electric automobile in the front, back, left and right directions is more than 1m, and according to the absorption and reflection principles in sound transmission, an ideal free sound field environment can be obtained from the edge of the anechoic chamber, so that the consistency of test results is higher;
The embodiment can meet the acquisition requirement of the sound signals of the electric automobile under the uniform speed working condition and the uniform acceleration working condition, and is used for identifying the drift frequency of the electric automobile in the follow-up mode, so that the accuracy of the sound signals of the electric automobile under the uniform speed working condition and the uniform acceleration working condition is improved through the design mode, the accuracy of the finally determined drift frequency of the electric automobile is further improved, and the accuracy of the frequency value of the electric automobile of the whole system is improved.
In a third embodiment, the system for determining a drift frequency of a low-speed alert sound of an electric vehicle according to the first embodiment is further defined, in the present embodiment, the microphone is further defined,
The method specifically comprises the following steps:
the microphone is arranged on the front end face of the electric automobile to be detected.
In this embodiment, the microphone is arranged according to the requirements of national standard GB/T37153-2018 "electric automobile low speed alert tone", specifically: the front end face of the electric automobile to be detected is 1.2 meters in height, and the distance from the front end face of the electric automobile to be detected is 2 meters.
According to the embodiment, the sound signals of the electric automobile under the uniform speed working condition and the uniform acceleration working condition can be effectively collected, unnecessary sound signals can be prevented from being collected, namely, adverse effects of noise factors are reduced, the accuracy of the drift frequency of the finally determined electric automobile is further improved, and the accuracy of the whole system to the frequency value of the electric automobile is improved.
In a fourth embodiment, the present embodiment is further defined by the system for determining a drift frequency of a low-speed alert sound of an electric vehicle according to the first embodiment, in the present embodiment, the drift frequency determining module is further defined,
The method specifically comprises the following steps:
the drift frequency determining module comprises a spectrum acquisition unit, a drift frequency preliminary determining unit and a drift frequency final determining unit;
The spectrum acquisition unit is used for receiving the average self-power spectrum and the sound spectrum sent by the uniform acceleration sound acquisition unit and the uniform acceleration sound signal processing unit;
the drift frequency preliminary determination unit is used for selecting an order line according to the sound spectrum;
According to the order line, determining a frequency initial value under a uniform-speed working condition;
the drift frequency final determining unit is used for determining the drift frequency of the electric automobile according to the frequency initial value and the average self-power spectrum under the uniform speed working condition, and specifically comprises the following steps:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value and the range value under the uniform-speed working condition, and determining the highest peak point as the drift frequency of the electric automobile.
After determining the order line, determining the frequency value of each constant-speed working condition on the order line, marking the frequency value as a frequency initial value, setting a range value such as + -2Hz, acquiring a frequency value region (frequency initial value-2 Hz, frequency initial value + -2 Hz) according to the frequency initial value and the range value, finding the highest peak point on the average self-power spectrum according to the frequency value region, and determining the frequency corresponding to the peak point as the drift frequency of the electric automobile, namely the accurate drift frequency.
In this embodiment, a specific structure and function of the drift frequency determining module are provided, where the drift frequency preliminary determining unit obtains a frequency initial value under a constant-speed working condition by selecting an order line, and a basis for determining the drift frequency of the electric automobile on an average self-power spectrum can be provided, where the basis can realize that the final determination of the drift frequency of the electric automobile is accurate, and the accuracy of the whole system to the frequency value of the electric automobile is improved.
In a fifth embodiment, fig. 12 is a schematic flow chart of the method of the present invention, as shown in fig. 12, for an embodiment of a method for determining a drift frequency of a low-speed alert sound of an electric vehicle.
The method comprises the following steps:
step 1, acquiring sound signals of an electric automobile under a uniform-speed working condition;
Acquiring sound signals of the electric automobile under a uniform acceleration working condition;
step 2, processing the sound signal under the uniform-speed working condition to obtain an average self-power spectrum;
Processing the sound signal of the electric automobile under the uniform acceleration working condition to obtain a sound spectrum;
And step 3, determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum.
According to the embodiment, firstly, the sound signal of the electric automobile under the uniform speed working condition and the sound signal of the electric automobile under the uniform acceleration working condition are obtained, namely, the sound signal under the uniform speed working condition is processed, the continuous sound signal of the automobile in the whole acceleration process is recorded, and the continuous sound frequency spectrum can be collected.
According to the roughly determined drift frequency of each vehicle speed, the corresponding peak point is selected on the average self-power spectrum under the uniform speed working condition, so that the accurate drift frequency can be obtained, and the inaccuracy caused by the fact that the average self-power spectrum has a plurality of peak values can be solved, so that the real drift frequency cannot be accurately determined.
In the sixth embodiment, the method for determining the drift frequency of the low-speed alert sound of the electric vehicle according to the fifth embodiment is further limited, in the present embodiment, the step 3 is further limited,
The method specifically comprises the following steps:
step 3.1, selecting an order line according to the sound spectrum;
Step 3.2, determining a frequency initial value under a uniform-speed working condition according to the order line;
step 3.2 is the rough determination of the drift frequency;
Step 3.3, determining the drift frequency of the electric automobile according to the frequency initial value under the uniform-speed working condition and the average self-power spectrum, wherein the drift frequency is specifically as follows:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value and the range value under the uniform-speed working condition, and determining the highest peak point as the drift frequency of the electric automobile.
The step 3.3 is the accurate determination of the drift frequency.
In the embodiment of the present market, the initial value of the frequency under the constant-speed working condition is determined according to the order line, the initial value is very effective for the finally determined drift frequency of the electric automobile, and the accuracy of the finally determined drift frequency of the electric automobile can reach nearly hundred percent.
In the seventh embodiment, the method for determining the drift frequency of the low-speed alert sound of the electric vehicle according to the sixth embodiment is further limited, in the present embodiment, the step 3.1 is further limited,
The method specifically comprises the following steps:
Step 3.1.1, setting a sound pressure level threshold;
And 3.1.2, selecting an order line with a sound pressure level greater than the sound pressure level threshold according to the sound spectrum.
In this embodiment, a continuous "bright line" with a larger sound pressure level, that is, an order line, can be found through the "sound spectrum", and the order line is generated due to the peak frequency drift, so that the drift frequency of each vehicle speed can be roughly determined along the order line, further, the accuracy of the finally determined drift frequency of the electric vehicle is improved, and the accuracy of the method of this embodiment to the frequency value of the electric vehicle is improved.
In an eighth embodiment, the method for determining a drift frequency of a low-speed alert sound of an electric vehicle according to the fifth embodiment is further defined, in the present embodiment, the sound spectrum is further defined,
The method specifically comprises the following steps:
The sound spectrum takes the vehicle speed as an ordinate, the frequency (Hz) as an abscissa, and the gray scale represents the sound pressure level.
In this embodiment, time or vehicle speed (the uniform acceleration working condition, the corresponding relationship between time and vehicle speed) is taken as an ordinate, frequency (Hz) is taken as an abscissa, the gray scale represents the sound pressure level, sound data in the uniform acceleration process is generated into a sound spectrum, an accurate data relationship and a data result of the frequency and the sound pressure level measured by the electric vehicle under the uniform acceleration working condition can be given, an initial value of the drift frequency of the electric vehicle can be determined according to the data relationship and the result, and an effective data basis is provided for the accurate frequency value to be determined finally.
In a ninth embodiment, the method for determining a drift frequency of a low-speed alert sound of an electric vehicle according to the fifth embodiment is further defined, in this embodiment, the step of processing the sound signal under the constant-speed working condition to obtain an average self-power spectrum is further defined,
The method specifically comprises the following steps:
And processing the sound signal under the uniform-speed working condition by utilizing a hanning window and at least 66.6% overlapping average to obtain an average self-power spectrum.
In the embodiment, the Hanning window is adopted according to the requirements of national standard GB/T37153-2018 electric automobile Low speed prompt tone.
In a tenth embodiment, the present embodiment is directed to a computer device for determining a low-speed alert tone drift frequency method of an electric vehicle, including a memory and a processor, where the memory stores a computer program, and the processor executes the steps of the method for determining a low-speed alert tone drift frequency of an electric vehicle as described above when running the computer program stored in the memory.
The present embodiment has corresponding technical features to the above-described method for determining the drift frequency of the low-speed alert sound of the electric vehicle, and thus the embodiment will not be described in detail.
In an eleventh embodiment, this embodiment is a specific example of a method for determining a drift frequency of a low-speed alert sound of an electric vehicle.
The method specifically comprises the following steps:
(1) Vehicle preparation: the vehicle is positioned in a semi-anechoic chamber with a rotary drum, and the nearest distance from the front, the back, the left and the right of the vehicle to the front end of a wedge in the anechoic chamber is ensured to be more than 1m.
(2) Microphone arrangement: the microphone is placed at P, P' on the front face of the vehicle as shown in fig. 5.
(3) And (3) collecting uniform-speed working condition data: the vehicles respectively run at constant speeds of 5km/h, 10km/h, 15km/h and 20km/h, and the data acquisition equipment is used for acquiring sound. Each vehicle speed is collected for at least 5s.
(4) And (3) uniformly accelerating working condition data acquisition: the acceleration of the vehicle is kept to be 1m/s 2, the vehicle speed is evenly accelerated from 0km/h to 20km/h, and the data acquisition equipment is used for acquiring the sound in the whole acceleration process.
(5) And (3) data processing:
① The sound data of the ramp up process is generated as a "sound spectrum" with the vehicle speed on the ordinate and the frequency (Hz) on the abscissa and the gray scale representing the sound pressure level, as shown in fig. 6.
② The sound signals of the running speeds of 5km/h, 10km/h, 15km/h and 20km/h are respectively generated into average self-power spectrums by taking the amplitude dB (A) as an ordinate and the frequency (Hz) as an abscissa. The calculation of the data processing uses a hanning window and an overlap average of at least 66.6%.
(6) And (3) roughly determining drift frequency: a straight line parallel to the abscissa is made at the speed of 5km/h on the ordinate, an obvious ' order line ' is selected on the ' sound spectrum ', and the frequency value corresponding to the abscissa of the intersection point of the straight line and the selected ' order line ' is recorded and named as f1'. In this way, along this selected "order line", the frequency values f2', f3', f4' at the corresponding speeds 10km/h, 15km/h, 20km/h are determined and recorded, respectively. As shown in fig. 6.
The recording results are: f1 '=368.64 Hz, f2' =407.38 Hz, f3 '=453.49 Hz, f4' = 513.13Hz
(7) And (3) accurately determining drift frequency: the position of f1' = 368.64Hz is found on the abscissa of the self-power spectrum of the sound when the vehicle speed is 5km/h, the highest peak point is found in the range of +/-2 Hz near the position, and the frequency f1= 368.04 corresponding to the peak point is recorded, namely the accurate drift frequency is shown in fig. 7 and 11.
According to the method, each peak point corresponding to f2', f3', f4' is determined on the self-power spectrum of the sound with the speed of 10km/h, 15km/h and 20km/h respectively, and the accurate frequency values f2, f3 and f4 are obtained.
As shown in fig. 7-10.
The determination result is as follows: f1 =368.04, f2=407.22, f3=453.85, f4= 512.61
It is to be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (8)
1. A system for determining a low speed alert tone drift frequency of an electric vehicle, the system comprising: the device comprises an electric automobile working condition testing module, a uniform speed working condition module, a uniform acceleration working condition module and a drift frequency determining module;
The electric automobile working condition testing module comprises a microphone and a silencing chamber, the silencing chamber is used for accommodating an electric automobile to be detected and the microphone,
The microphone is used for acquiring sound signals generated by the electric automobile to be detected;
the constant-speed working condition module comprises a constant-speed sound acquisition unit and a constant-speed sound signal processing unit;
The constant-speed sound collection unit is used for collecting sound signals of the electric automobile under a constant-speed working condition;
the constant-speed sound signal processing unit is used for processing sound signals of the electric automobile under a constant-speed working condition to obtain an average self-power spectrum;
the uniform acceleration working condition module comprises a uniform acceleration sound acquisition unit and a uniform acceleration sound signal processing unit;
The uniform acceleration sound collection unit is used for collecting sound signals of the electric automobile under a uniform acceleration working condition;
the uniform acceleration sound signal processing unit is used for processing sound signals of the electric automobile under a uniform acceleration working condition to obtain a sound spectrum;
the drift frequency determining module is used for determining the drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum;
the drift frequency determining module comprises a spectrum acquisition unit, a drift frequency preliminary determining unit and a drift frequency final determining unit;
The spectrum acquisition unit is used for receiving the average self-power spectrum and the sound spectrum sent by the uniform acceleration sound acquisition unit and the uniform acceleration sound signal processing unit;
the drift frequency preliminary determination unit is used for selecting an order line according to the sound spectrum;
According to the order line, determining a frequency initial value under a uniform-speed working condition;
the drift frequency final determining unit is used for determining the drift frequency of the electric automobile according to the frequency initial value and the average self-power spectrum under the uniform speed working condition, and specifically comprises the following steps:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value and the range value under the uniform-speed working condition, and determining the highest peak point as the drift frequency of the electric automobile.
2. The system for determining the low-speed prompt tone drift frequency of the electric automobile according to claim 1, wherein the muffling chamber is a semi-muffling chamber, and the shortest distance between the front end of the wedge in the muffling chamber and the electric automobile to be detected in four directions of front, back, left and right is greater than 1m.
3. The system for determining a low-speed alert tone drift frequency of an electric vehicle according to claim 1, wherein the microphone is disposed on a front end surface of the electric vehicle to be detected.
4. A method for determining a drift frequency of a low-speed alert tone of an electric vehicle, the method comprising:
step 1, acquiring sound signals of an electric automobile under a uniform-speed working condition;
Acquiring sound signals of the electric automobile under a uniform acceleration working condition;
step 2, processing the sound signal under the uniform-speed working condition to obtain an average self-power spectrum;
Processing the sound signal of the electric automobile under the uniform acceleration working condition to obtain a sound spectrum;
Step 3, determining drift frequency of the electric automobile according to the average self-power spectrum and the sound spectrum;
The step3 specifically includes:
step 3.1, selecting an order line according to the sound spectrum;
Step 3.2, determining a frequency initial value under a uniform-speed working condition according to the order line;
Step 3.3, determining the drift frequency of the electric automobile according to the frequency initial value under the uniform-speed working condition and the average self-power spectrum, wherein the drift frequency is specifically as follows:
setting a range value, acquiring a highest peak point on the average self-power spectrum according to the frequency initial value under the uniform speed working condition and the range value, and determining the highest peak point as the drift frequency of the electric automobile.
5. The method for determining a low-speed alert tone drift frequency of an electric vehicle according to claim 4, wherein the step 3.1 specifically comprises:
Step 3.1.1, setting a sound pressure level threshold;
And 3.1.2, selecting an order line with a sound pressure level greater than the sound pressure level threshold according to the sound spectrum.
6. The method for determining a low-speed alert tone drift frequency of an electric vehicle according to claim 4, wherein the sound spectrum has a vehicle speed as an ordinate, a frequency as an abscissa, a frequency unit as Hz, and a gray scale representing a sound pressure level.
7. The method for determining a low-speed alert tone drift frequency of an electric vehicle according to claim 4, wherein the processing the sound signal under the uniform-speed working condition to obtain an average self-power spectrum specifically comprises: and processing the sound signal under the uniform-speed working condition by utilizing a hanning window and at least 66.6% overlapping average to obtain an average self-power spectrum.
8. A computer device comprising a memory and a processor, the memory having stored therein a computer program, characterized in that the processor, when running the computer program stored in the memory, performs the steps of the method of any of claims 4 to 7.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210631146.0A CN115171719B (en) | 2022-06-06 | 2022-06-06 | System, method and computer equipment for determining drift frequency of low-speed prompt tone of electric automobile |
| PCT/CN2023/090296 WO2023236672A1 (en) | 2022-06-06 | 2023-04-24 | System and method for determining drift frequency of acoustic vehicle alerting system of electric vehicles running at low speed, and computer device |
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| CN202210631146.0A CN115171719B (en) | 2022-06-06 | 2022-06-06 | System, method and computer equipment for determining drift frequency of low-speed prompt tone of electric automobile |
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| CN115171719A CN115171719A (en) | 2022-10-11 |
| CN115171719B true CN115171719B (en) | 2024-05-07 |
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| CN107571792A (en) * | 2017-09-25 | 2018-01-12 | 吉林大学 | A kind of electric car low speed prompting system for electrical teaching and control method |
| CN108944662A (en) * | 2018-05-31 | 2018-12-07 | 中国重汽集团福建海西汽车有限公司 | A kind of low vehicle speeds reminding method and its system |
| WO2023236672A1 (en) * | 2022-06-06 | 2023-12-14 | 中国第一汽车股份有限公司 | System and method for determining drift frequency of acoustic vehicle alerting system of electric vehicles running at low speed, and computer device |
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| CN112298030A (en) * | 2020-10-16 | 2021-02-02 | 中国第一汽车股份有限公司 | Frequency response test system and method for low-speed prompt tone device of electric automobile |
| GB2602007A (en) * | 2020-12-14 | 2022-06-22 | Pss Belgium Nv | Vehicle warning system |
| CN114148254B (en) * | 2021-11-30 | 2024-02-13 | 重庆长安汽车股份有限公司 | Automobile low-speed prompt tone realization system |
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