CN109521222B - Method for improving laser speed measurement precision - Google Patents
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- CN109521222B CN109521222B CN201811333089.8A CN201811333089A CN109521222B CN 109521222 B CN109521222 B CN 109521222B CN 201811333089 A CN201811333089 A CN 201811333089A CN 109521222 B CN109521222 B CN 109521222B
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- 238000005259 measurement Methods 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000001914 filtration Methods 0.000 claims abstract description 16
- 238000004364 calculation method Methods 0.000 claims abstract description 15
- 230000010355 oscillation Effects 0.000 claims abstract description 3
- 230000003595 spectral effect Effects 0.000 claims description 24
- 238000001228 spectrum Methods 0.000 claims description 16
- 230000003321 amplification Effects 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 4
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 4
- 238000000827 velocimetry Methods 0.000 claims 3
- 239000013307 optical fiber Substances 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/64—Devices characterised by the determination of the time taken to traverse a fixed distance
- G01P3/68—Devices characterised by the determination of the time taken to traverse a fixed distance using optical means, i.e. using infrared, visible, or ultraviolet light
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Abstract
The invention discloses a method for improving laser speed measurement precision, which belongs to the technical field of laser speed measurement, and comprises the following steps of: detecting a mixing signal of local oscillation light emitted by a laser source and an echo signal reflected by a target object at the current moment; s2: obtaining distance and speed data in the mixing signals, and calculating a speed component in the distance and speed data; s3: and predicting the speed information at the current moment, and carrying out filtering calculation on the speed component according to the predicted value. The method solves the problem of large error caused by simply taking the frequency of the highest point of the amplitude in the amplitude-frequency characteristic as the Doppler frequency value in the prior art, and further improves the precision of laser speed measurement through filtering calculation.
Description
Technical Field
The invention relates to the technical field of laser speed measurement, in particular to a method for improving laser speed measurement precision.
Background
The laser Doppler velocimeter measures the laser Doppler signal reflected by a moving target and then obtains the speed according to the relation between the speed and the Doppler frequency. The laser measurement has no interference to the flow field, and the speed measurement range is wide, and the Doppler frequency and the speed are in linear relation, and the temperature and the pressure of the point are irrelevant, so that the laser Doppler speed measurement has obvious advantages compared with the microwave radar speed measurement application aspect. The laser speed measurement technology can be widely applied to the application occasions of fluid measurement, wind field measurement, vehicle-mounted autonomous navigation, accurate speed measurement when an aircraft lands and the like.
Existing laser doppler velocimetry typically measures velocity by measuring the laser doppler shift. The measurement accuracy of the laser doppler frequency shift is related to the velocity measurement accuracy. In laser doppler velocity measurement, Fast Fourier Transform (FFT) calculation results are not continuous in frequency, the accuracy depends on the sampling rate and the number of FFT points, and the frequency of the highest point of amplitude in the amplitude-frequency characteristic is simply used as the doppler frequency value, which may cause a large error.
Disclosure of Invention
The embodiment of the invention provides a method for improving laser speed measurement precision, which is used for solving the problem of large error in the prior art.
The embodiment of the invention provides a method for improving the laser speed measurement precision, which comprises the following steps,
the laser source is connected with other components through optical fibers, and after frequency-modulated local oscillator light and echo signals reflected by a target object are mixed, the mixed frequency signals are detected by using a PIN type silicon photodiode;
and filtering, signal amplification and FFT operation are carried out on the detected electric signals, and then distance and speed information is calculated.
The FFT operation can be realized by adopting an FPGA, and the amplified signal is multiplied by the Hanning window coefficient point by point before the amplified signal is subjected to FFT transformation in the FPGA.
In order to reduce the frequency spectrum leakage, signals are weighted by a Hanning window with the window length same as the number of FFT points, FFT operation is carried out, a group of frequency spectrum values can be obtained, the maximum value in the frequency spectrum corresponds to a spectral line and is marked as n, two spectral lines n-1 and n-2 on the left side of the maximum spectral line n are taken, two spectral lines n +1 and n +2 on the right side and the maximum spectral line n form a group of 5-point spectral lines for correction. To obtain a correction value of
In the formula, s (n) represents an FFT spectrum value at n points.
The above is the correction of the frequency spectrum value of each point after the FFT operation is carried out on the n point data. According to the formula
The speed of the moving object can be calculated, wherein lambda is the wavelength, and theta is the included angle between the laser beam direction and the moving direction of the object.
Filtering the calculated velocity component:
a: setting a system initial value and an initial coefficient;
b: the speed value of the current moment is estimated to meet the requirement of vj＝viWherein v isjFor a predicted value of the speed value at the current moment, viRepresenting a system speed value;
c: the variance of the speed at the current moment is estimated to meet the requirement
Wherein p isjFor an estimated value of the variance of the speed at the current moment, q1Is a coefficient, piThe variance corresponding to the current system speed value;
d: calculating a gain value satisfying:
wherein q is2Is a coefficient;
e: the speed value at the current moment is obtained by calculating the estimated value and the actual measurement speed of the speed value at the current moment, and the following conditions are met:
vt＝vj+kg(v-vj)
wherein v represents the measured velocity;
f: calculating the variance of the speed at the current moment to meet the requirement
g: updating the system value, vi＝vt，pi＝pt；
h: and (c) repeating the steps b-g before the target object is in the detection area or the calculation is manually stopped, and carrying out filtering calculation on the velocity component at any subsequent moment to obtain an accurate velocity value at any moment.
The embodiment of the invention extracts the mixing signal, processes the mixing signal, and performs filtering calculation on the speed information, thereby solving the problem of large error caused by simply taking the frequency of the highest point of amplitude in the amplitude-frequency characteristic as the Doppler frequency value in the prior art.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
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Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
FIG. 1 is a diagram of a laser Doppler velocity measurement system;
FIG. 2 is a flow chart of the present invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
A first embodiment of the present invention provides a method for improving laser speed measurement accuracy, as shown in fig. 1, a system corresponding to the method is a laser speed measurement system, and includes a laser and a laser control circuit connected to the laser, where the laser is further connected to an optical fiber circuit, the optical fiber circuit is respectively connected to a PIN photodiode and a transceiver lens, and the transceiver lens collects information related to a target object. The information collected by the PIN photodiode is transmitted to the signal collecting and processing circuit through the amplifying circuit, and finally the collected signal is processed by the signal collecting and processing circuit and then output and displayed.
In the embodiment, the adopted laser is a narrow-linewidth single-frequency fiber laser, the laser has small volume, light weight and low power consumption, and the linewidth requirement is not more than 10 kHz. The principle of the invention is that a laser source is connected with other components through optical fibers, after frequency-modulated local oscillator light is mixed with echo signals reflected by a target object, a PIN type silicon photodiode is used for detecting the mixed frequency signals, filtering, signal amplification and FFT operation are carried out on the detected electric signals, and then distance and speed information is calculated.
Specifically, the method of the present invention can be described as the following steps:
step S1: and detecting a mixing signal of local oscillation light emitted by the optical fiber laser and an echo signal reflected by the target object by using the PIN type silicon photodiode.
Step S2: and carrying out signal processing on the detected mixed signal, acquiring distance and speed data in the mixed signal, and calculating a speed component in the distance and speed data.
Step S3: and estimating the speed information of the next moment according to the speed information of the previous moment, and carrying out filtering calculation on the speed component according to the estimated value.
Optionally, the FFT operation of the present invention is implemented by using an FPGA, and the amplified signal is multiplied point by a hanning window coefficient before FFT conversion of the amplified signal in the FPGA, so that spectrum leakage in a frequency domain due to truncation of the signal in time can be reduced. The signal is directly cut off, so that large frequency spectrum leakage can be generated, and the leaked frequency spectrum in subsequent processing causes frequency spectrum aliasing to influence the extraction of the target speed. In order to reduce the frequency spectrum leakage, signals are weighted by a Hanning window with the window length same as the number of FFT points, FFT operation is carried out, a group of frequency spectrum values can be obtained, the maximum value in the frequency spectrum corresponds to a spectral line and is marked as n, two spectral lines n-1 and n-2 on the left side of the maximum spectral line n are taken, two spectral lines n +1 and n +2 on the right side and the maximum spectral line n form a group of 5-point spectral lines for correction.
The steps are as follows:
step S201: weighting the signal by a Hanning window with the same window length as the number of FFT operation points, and carrying out FFT operation to obtain a group of corresponding frequency spectrum values.
Step S202: and taking the spectral line with the maximum value in the group of spectral values as n, taking the two spectral lines on the left side of the spectral line as n-1 and n-2, taking the two spectral lines on the right side as n +1 and n +2, and correcting 5 spectral lines in total, wherein the correction value meets the following requirements:
wherein S (n) represents an FFT spectrum value at n points, and f0' watchDisplaying a correction value;
step S203: according to
And calculating the speed of the target object, wherein lambda is the wavelength, and theta is the included angle between the laser beam direction and the object movement direction.
And filtering the speed component according to the calculated speed value of the target object, wherein the optional step is realized by adopting an FPGA (field programmable gate array) if the step is real-time processing, and can also be processed by adopting a general-purpose computer if the step is post-processing.
The filtering calculation of the velocity component specifically comprises the following steps:
s31: setting a system initial value and an initial coefficient;
s32: the speed value of the current moment is estimated to meet the requirement of vj＝viWherein v isjFor a predicted value of the speed value at the current moment, viRepresenting a system speed value;
s33: the variance of the speed at the current moment is estimated to meet the requirement
Wherein p isjFor an estimated value of the variance of the speed at the current moment, q1Is a coefficient, piThe variance corresponding to the current system speed value;
s34: calculating a gain value satisfying:
wherein q is2Is a coefficient;
s35: the speed value at the current moment is obtained by calculating the estimated value and the actual measurement speed of the speed value at the current moment, and the following conditions are met:
vt＝vj+kg(v-vj)
wherein v represents the measured velocity;
s36: calculating the variance of the speed at the current moment to meet the requirement
S37: updating the system value, vi＝vt，pi＝pt；
S38: and repeating the steps S32-S37 before the target object is in the detection area or the calculation is manually stopped, and carrying out filtering calculation on the velocity component at any subsequent moment to obtain the accurate velocity value at any moment.
In the above steps, the initial value of the system and the specific setting of the initial coefficient satisfy: the initial value of the speed is set to 0.5, the corresponding initial value of the variance is set to 10, and the coefficient q1、q2Set to 0.5 and 0.8, respectively. The initial value of the system and the specific setting of the initial coefficient can be changed within a certain range, and finally, the initial value and the specific setting of the initial coefficient can be converged to the setting value.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that the invention can be practiced without departing from the spirit of the invention and the scope of the appended claims
In the context of the present invention, many forms may be made which are within the scope of the present invention.
Claims (5)
1. A method for improving the laser speed measurement precision is characterized by comprising the following steps,
s1: detecting a mixing signal of local oscillation light emitted by a laser source and an echo signal reflected by a target object at the current moment;
s2: obtaining distance and speed data in the mixing signals, and calculating a speed component in the distance and speed data;
s3: estimating the speed information of the current moment, and carrying out filtering calculation on the speed component according to the estimated value;
step S3 specifically includes the following steps:
s301: setting a system initial value and an initial coefficient;
s302: the speed value of the current moment is estimated to meet the requirement of vj＝viWherein v isjFor a predicted value of the speed value at the current moment, viRepresenting a system speed value;
s303: the variance of the speed at the current moment is estimated to meet the requirement
Wherein p isjFor an estimated value of the variance of the speed at the current moment, q1Is a coefficient, piThe variance corresponding to the current system speed value;
s304: calculating a gain value satisfying:
wherein q is2Is a coefficient;
s305: the speed value at the current moment is obtained by calculating the estimated value and the actual measurement speed of the speed value at the current moment, and the following conditions are met:
vt＝vj+kg(v-vj)
wherein v represents the measured velocity;
s306: calculating the variance of the speed at the current moment to meet the requirement
S307: updating the system value, vi＝vt，pi＝pt；
S308: and repeating the steps S302-S307 before the target object is in the detection area or the calculation is manually stopped, and carrying out filtering calculation on the velocity component at any subsequent moment to obtain the accurate velocity value at any moment.
2. The method for improving the accuracy of laser velocimetry as claimed in claim 1, wherein step S2 further includes:
and filtering, signal amplification and Fast Fourier Transform (FFT) operation are carried out on the detected mixed frequency signal, distance and speed data in the mixed frequency signal are obtained, and a speed component in the distance and speed data is calculated.
3. The method for improving the accuracy of laser velocimetry as claimed in claim 2, wherein step S2 further includes:
after filtering and signal amplification are carried out on the mixed frequency signal, point-by-point multiplication is carried out on the amplified mixed frequency signal and a Hanning window coefficient, and then FFT operation is carried out.
4. The method of claim 3, wherein in step S2, the performing the FFT operation further comprises:
s201: weighting the amplified mixing signals by using a Hanning window with the same window length as the number of FFT operation points, and carrying out FFT operation to obtain a group of corresponding frequency spectrum values;
s202: and taking the spectral line with the maximum value in the group of spectral values as n, taking the two spectral lines on the left side of the spectral line as n-1 and n-2, taking the two spectral lines on the right side as n +1 and n +2, and correcting 5 spectral lines in total, wherein the correction value meets the following requirements:
wherein S (n) represents an FFT spectrum value at n point, f'0Indicating a correction value;
s203: according to
And calculating the actual measurement speed of the target object, wherein lambda is the wavelength, and theta is the included angle between the laser beam direction and the object movement direction.
5. The method for improving the accuracy of laser velocimetry as claimed in claim 4, wherein step S3 specifically comprises:
s31: estimating the speed information of the current moment;
s32: calculating the speed information of the current moment according to the estimated speed information and the actually measured speed;
s33: and repeating the steps S31-S32, and continuously carrying out filtering calculation on the speed component of the target object until the target object is separated from the detection area or the calculation is manually stopped.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103777034A (en) * | 2014-01-22 | 2014-05-07 | 天津大学 | Two-dimensional point range type laser Doppler speed measurement device |
| CN205690996U (en) * | 2016-06-08 | 2016-11-16 | 无锡机电高等职业技术学校 | A kind of photoelectrical velocity measure equipment |
| CN108279317A (en) * | 2018-01-23 | 2018-07-13 | 江西省智成测控技术研究所有限责任公司 | A kind of space filtering tachogenerator device and the method for improving rate accuracy |
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| CN101887126B (en) * | 2010-06-27 | 2013-04-03 | 清华大学 | Double-frequency laser Doppler velocity measurement method and device |
| KR101252590B1 (en) * | 2010-10-19 | 2013-04-12 | 한국표준과학연구원 | Detection method of Doppler signals as measured by Laser Doppler Anemometry |
| CN102706367B (en) * | 2012-06-19 | 2014-12-24 | 北京航空航天大学 | Accuracy testing and calculating method of single-beam laser speedometer for combined navigation |
| CN103076611B (en) * | 2013-01-09 | 2015-05-06 | 中国电子科技集团公司第十一研究所 | Method and device for measuring speed and distance by coherent detecting laser |
| CN104833816B (en) * | 2015-04-29 | 2018-04-10 | 中国人民解放军国防科学技术大学 | Laser Doppler speed measuring device and its speed-measuring method based on rotating grating |
| CN106199631B (en) * | 2016-09-28 | 2020-04-10 | 成都凯天电子股份有限公司 | Coherent wind finding radar wind speed measuring method |
| JP6691878B2 (en) * | 2017-02-06 | 2020-05-13 | 公益財団法人鉄道総合技術研究所 | Elastic wave measurement system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103777034A (en) * | 2014-01-22 | 2014-05-07 | 天津大学 | Two-dimensional point range type laser Doppler speed measurement device |
| CN205690996U (en) * | 2016-06-08 | 2016-11-16 | 无锡机电高等职业技术学校 | A kind of photoelectrical velocity measure equipment |
| CN108279317A (en) * | 2018-01-23 | 2018-07-13 | 江西省智成测控技术研究所有限责任公司 | A kind of space filtering tachogenerator device and the method for improving rate accuracy |
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