CN105891841A - Vehicle laser radar distance and velocity measurement method - Google Patents

Abstract

The invention provides a vehicle laser radar distance and velocity measurement method, which is characterized by comprising a first step of driving, via a laser drive circuit, a laser to generate a narrow linewidth single frequency laser with continuous amplitude; a second step of, outputting, via an optical splitter, measurement light in the narrow linewidth single frequency laser outputted by the laser to an electrooptical modulator, and allowing the remaining reference light to pass through an acoustic optical modulator to generate a frequency offset for use locally as a reference signal; a third step of generating, by a local pulse generating circuit, a pseudo-random code, and obtaining a probe signal of a laser radar; a fourth step of enabling the probe signal to pass through an erbium-doped optical fiber amplifier so that the optical signal peak power can be amplified to 100W order or greater to form an amplified optical signal; a fifth step of mixing the amplified optical signal with the reference signal to output a heterodyne signal; a sixth step of calculating a correlation function of the heterodyne signal and a modulation code, so as to obtain the distance of a target; and a seventh step of analyzing unequal interval data acquired through heterodyne signal sampling, and thus obtaining the speed of the moving target.

Description

Mobile lidar distance speed measurement method

Technical field

The present invention relates to as laser radar technique field, particularly to a kind of mobile lidar distance speed Degree measuring method.

Background technology

In the automotive industry, millimetre-wave radar uses the mode of frequency modulation continuous wave to achieve road mesh Subject distance and the synchronous detecting of speed, this technology obtains extensively in automobile assistant driving and automatic Pilot General application.But, the spatial resolution of millimetre-wave radar is poor, its imaging energy to road environment Power is not enough.Such as, being easy to two target recognitions in target-rich environment is single target, causes The mistaken verdict of decision-making end, potential initiation vehicle accident.In order to improve target detection spatial resolution, Selecting laser is optimal selection as launching light source, because laser has excellent collimating effect.To the greatest extent Pipe laser infrared radar has lot of advantages compared to millimetre-wave radar, but mobile lidar can only be surveyed at present The distance of amount target, it is impossible to use the speed of doppler information synchro measure target.

Existing business mobile lidar obtains target by the way of calculating target range rate of change Speed.The speed that this method obtains, compared with Doppler's mode, its error is relatively big and the time of acquisition Longer.In terms of research, laser radar based on continuous wave mode is currently also had to realize distance and speed Synchro measure, the certainty of measurement of its distance and speed all can meet the demand of intelligent driving.But, Being all continuous wave owing to launching signal, its peak power is affected by device is limited in below milliwatt, Therefore the theoretical detection limit of laser radar it is accessible to.It addition, the mode of continuous wave is by this Earth signal with receive signal mixing obtain frequency difference mode measure target range and speed, when work with Under target-rich environment, the service behaviour of which is unstable.In order to ensure the stable detection of road target, Automobile industry suggestion uses pulse type laser radar, and this is also up to the present business mobile lidar Pulse mode is all used to realize the reason of range measurement.

Central authorities of Toyota of Japan institute proposes a kind of cycle code that inserts in pseudo noise code and constitutes modulation code Mode realize the synchro measure of road target distance and speed.Transmitting terminal uses modulation code modulation to send out Penetrating the amplitude of optical signal, receiving terminal is by calculating the correlation function acquisition receiving reflected signal with modulation code Laser time of flight thus measure the distance of target.By reflected signal will be received with local with reference to letter Number mixing output heterodyne signal, analyze heterodyne signal frequency obtain Doppler frequency thus measure mesh Target speed.Owing to receiving signal amplitude by pscudo-random codc modulation, the heterodyne letter of optical-electrical converter output Number it is no longer that continuous print is sinusoidal wave, but zonal cooling.If modulation code is not inserted into cycle code, will The equal interval sampling data to Doppler signal cannot be obtained, and then fast Fourier transform cannot be used The frequency of methods analyst Doppler signal.Although the mode of insertion cycle code is capable of pulse type laser The distance speed sync of radar is measured, but the cycle code inserted makes the autocorrelation performance of pseudo noise code It is deteriorated, affects the distance detection performance of laser radar.On the other hand, the sampling to Doppler signal Occurring at cycle code position, sample rate is low, limits the highest frequency scope of Doppler signal, i.e. limits Make measurable maximum speed.Moreover, receiving terminal one beam splitter of use of this laser radar will Receiving signal and be divided into two-way, a road directly exports, another road and local signal mixing output heterodyne signal, Make the local receiver weak signal service efficiency to receiving low, affect the detection performance of laser radar. Receiving terminal uses two optical-electrical converters to export reception signal and heterodyne signal respectively, which increases sharp The equipment cost of optical radar.Therefore, although the pulsed method of central authorities of Toyota institute can from principle To realize the synchro measure of distance and speed, but measurement performance and become present aspect also far from meet The requirement of mobile lidar.Such as, on a highway, legal limit up to 120km/h, when During two cars relative motion, its relative velocity is 240km/h.Feelings in view of the furious driving in reality Condition, maximal rate also can increase further.When also having front vehicles with certain speed away from this car, its Speed limit in the case of legal it is contemplated that for-120km/h (negative sign represents direction, i.e. away from this car), The method of this central authorities of Ye Shi Toyota institute cannot be measured.

Summary of the invention

The present invention is carried out to solve the problems referred to above, it is therefore intended that provide a kind of synchro measure, Efficiency is high, and performance is high, the mobile lidar distance speed measurement method that scope of measuring is wide.

The mobile lidar distance speed measurement method that the present invention provides, has the feature that, bag Include following steps:

Step one, is driven laser instrument to produce amplitude continuous print narrow-linewidth single frequency laser by laser drive circuit；

Step 2, measures light and exports electric light in the narrow-linewidth single frequency laser that laser instrument is exported by beam splitter Manipulator, remaining reference light produces frequency shift (FS) by third contact of a total solar or lunar eclipse manipulator, for locally as reference Signal；

Step 3, local pulse-generating circuit generates pseudo noise code, and is driven electric light to adjust by pseudo noise code The device processed amplitude modulation(PAM) to narrow-linewidth single frequency laser, it is thus achieved that the detectable signal of laser radar；

Step 4, makes optical signal peak power be amplified to by erbium-doped fiber amplifier detectable signal 100W magnitude amplification formed above optical signal, and amplification optical signal is projected measurement by collimation camera lens In target；

Step 5, will amplify optical signal and reference signal mixing output heterodyne signal；

Step 6, calculates the correlation function of heterodyne signal and modulation code, correlation function peak value determines narrow The live width single-frequency laser flight time, and then obtain the distance of target；And

Step 7, analyzes the unequal interval data that heterodyne signal sampling obtains, and obtains moving target and produces The frequency of Doppler signal, thus obtain the speed of moving target.

The mobile lidar distance speed measurement method that invention provides, also has a feature in that it In, in step 2, acousto-optic modulator produces the deviant size of frequency shift (FS) to incite somebody to action to local reference signal Negative frequency integral shift is criterion to positive frequencies, and low-limit frequency one week of heterodyne signal to be met Phase is less than the length launching signal.

The mobile lidar distance speed measurement method that invention provides, also has a feature in that it In, heterodyne signal is expressed as:

E₁For local reference light power,

E₂T () is reception signal light power,

f_DFor receiving the frequency difference between light and reference light,

Heterodyne signal is sampled with pulse width for the sampling period, the sampled data obtained and modulation yardage Calculate correlation function.

The mobile lidar distance speed measurement method that invention provides, also has a feature in that it In, the sampling signal frequency analysis method of unequal interval data:

According to Fourier transform formula:

$F\left(\mathrm{\ω}\right)=\underset{-\mathrm{\∞}}{\overset{\mathrm{\∞}}{\∫}}f\left(t\right)e^{-j\mathrm{\ω}t}dt---\left(1\right)$

Here f (t) is time-domain signal,

In order to obtain the frequency spectrum of continuous signal on computers, it is necessary to first to continuous signal windowing, it is assumed that Window function is a rectangular function being defined on [0, T] interval, and amplitude is 1, then formula (1) becomes It is changed to:

$F\left(\mathrm{\ω}\right)=\underset{0}{\overset{T}{\∫}}f\left(t\right)e^{-j\mathrm{\ω}t}dt---\left(2\right)$

Integrating range is used N point sampling, formula (2) are transformed to following summation formula:

$F\left(\mathrm{\ω}\right)=\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}{\mathrm{\ΔT}}_i---\left(3\right)$

t_iFor the time location of sampled data points,

ΔT_i(i=0,1 ..., N-2) it is interval [t_i,t_i+1] interval, if Δ T₁=Δ T₂=...=Δ T_N-2=Δ T, public Formula (4) just can transform to the Fourier transformation of finite sequence:

$F\left(\mathrm{\ω}\right)=\mathrm{\Δ}T\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}=\frac{1}{F_s}\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}---\left(4\right)$

F_s=1/ Δ T is sample rate,

In classical Digital Signal Processing, discrete Fourier transform is defined as:

$X\left(k\right)=\underset{n=0}{\overset{N-1}{\Σ}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}nk}---\left(5\right)$

K is numerical frequency,

Comparison expression (4) and formula (5), can obtain:

t_i=t₀+nΔT (6)

$\begin{array}{cc}\mathrm{\ω}=2\mathrm{\π}f=2\mathrm{\π}(-\frac{1}{2}+\frac{k}{N})F_s& (k=0,1,...,N-1)\end{array}---\left(7\right)$

By formula (6) and formula (7), simulated time and analog frequency can be obtained according to digital value n and k, Formula (3) is carried out the form that conversion is allowed to have formula (4):

$F\left(\mathrm{\ω}\right)=\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right){\mathrm{\ΔT}}_i{e}^{-{\mathrm{j\ωt}}_i}=\underset{i=0}{\overset{N-2}{\Σ}}\tilde{f}\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}---\left(8\right)$

The heterodyne signal that amplitude is modulated, Δ T_iBe between two 1 yard time Between be spaced.

The mobile lidar distance speed measurement method that invention provides, also has a feature in that it In, formula (3) carries out conversion being allowed to have the form of formula (4) is to make fast Fourier Mapping algorithm can be used in unequal interval sampled analogue signals, and signal amplitude is multiplied by two 1 code interval Process be referred to as signal amplitude correction, the signal after amplitude correction just can directly use in quick Fu Leaf transformation completes the frequency analysis of heterodyne signal.

The mobile lidar distance speed measurement method that invention provides, also has a feature in that it In, narrow-linewidth single frequency laser is pulse train, can launch letter by using erbium-doped fiber amplifier to amplify Number peak power.

The mobile lidar distance speed measurement method that invention provides, also has a feature in that it In, laser instrument is narrow-linewidth single frequency semiconductor laser.

The mobile lidar distance speed measurement method that invention provides, also has a feature in that it In, beam splitter uses 99% measurement light in the narrow-linewidth single frequency laser that laser instrument is exported by 99:1 beam splitter Output is to electrooptic modulator, and remaining 1% produces frequency shift (FS) by third contact of a total solar or lunar eclipse manipulator, makees for this locality For reference signal.

Invention effect and effect

According to mobile lidar distance speed measurement method involved by the present embodiment, narrow-linewidth single frequency swashs Light is pulse train, can improve the detection stability of laser radar, meets laser safety simultaneously and uses mark Accurate；Use single photoelectric detector on the one hand can improve the service efficiency receiving signal, on the other hand A beam splitter and an optical-electrical converter can be saved, reduce equipment cost；Pscudo-random codc modulation light The modulation of light source can be realized, compared to light frequency modulation, phase place by source amplitude by external modulation mode Modulation has advantage simple to operate, cheap；Pscudo-random codc modulation is used to launch light source amplitude, Need not insert cycle code in modulation code, make the coherence of modulation code be maintained, additionally improve The scope of tachometric survey, makes the velocity to moving target in road environment all can be detected；Use relevant The method of detection can amplify reception signal by local signal, has detection compared to directly detection sensitive Spend high advantage；After the heterodyne signal received is done simple amplitude correction, directly use in quick Fu The frequency of leaf transformation Algorithm Analysis heterodyne signal, has fast operation, a feature that noiseproof feature is good, And having special FFT hardware module to complete this work, system cost is low；It is operable with target-rich environment.

Accompanying drawing explanation

Fig. 1 is the structure principle chart of present invention laser radar in an embodiment；

Fig. 2 is present invention optical-electrical converter output heterodyne signal waveform in an embodiment；

Fig. 3 is that present invention use heterodyne method in an embodiment exports with direct Detection Method optical-electrical converter Signal and the comparison diagram of modulation code correlation function；

Fig. 4 is the present invention being given under different Doppler frequency in an embodiment, and correlation function peak value is subject to The situation of phase of received signal impact, also provides the comparison diagram of correlation function peak-peak and minor peaks；

Fig. 5 be the present invention in an embodiment be given optical-electrical converter output heterodyne signal waveform and For analyzing the heterodyne signal oscillogram through amplitude correction of Doppler signal frequency；And

Fig. 6 is that the present invention unequal interval sampled signal frequency spectrum analysis method that is given in an embodiment obtains The spectrogram of various frequency signals.

Detailed description of the invention

Referring to the drawings and embodiment is to mobile lidar distance tachometric survey involved in the present invention Method is explained in detail.

Fig. 1 is the structure principle chart of present invention laser radar in an embodiment.

It is used for as shown in Figure 1 measuring target range mobile lidar structural principle block diagram, is used Laser instrument is narrow-linewidth single frequency semiconductor laser, and output light keeps linear polarization.

Step one: Laser Driven module drive laser works is in continuous wave mode, and output amplitude is continuous Narrow-linewidth single frequency laser, enter step 2.

Step 2: 99% in the narrow-linewidth single frequency laser that laser instrument is exported by 99:1 beam splitter (is measured Light) output is to electrooptic modulator, and it is inclined that remaining 1% (reference light) produces frequency by third contact of a total solar or lunar eclipse manipulator Move, for locally as reference signal, enter step 3.

If local reference signal not being produced frequency shift (FS), when external object is static, receiving terminal The amplitude of output heterodyne signal is affected by phase of received signal, and phase place is a random value, thus Detection unstable properties.It addition, moving target have near and away from two kinds of motion modes, in order to distinguish The direction of motion, it is also desirable to frequency is produced certain skew.The size of deviant is with overall by negative frequency Moving positive frequencies is criterion, and one cycle of low-limit frequency heterodyne signal to be met is less than launching The length of signal.

Measurement light and local optical power fluctuation scheme:

Reference light can amplify reception signal light power, but the noise of reference light is also introduced into and is exaggerated, Therefore this locality reference light is unsuitable too strong.Photoelectric detector for mobile lidar can easily detect Microwatt level optical signal, laser instrument output light is in milliwatt level, therefore is used for the beam splitter measuring light with local light Select 99:1 beam splitter.

Step 3: the amplitude of electrooptic modulator modulation continuous light, makes the change of light amplitude meet pseudorandom The rule of code, the best autocorrelation performance.Local pulse-generating circuit generation pseudo noise code, and by Pseudo noise code drives the electrooptic modulator amplitude modulation(PAM) to narrow-linewidth single frequency laser, it is thus achieved that laser radar Detectable signal, enters step 4.

Step 4: make optical signal peak power be amplified to by erbium-doped fiber amplifier detectable signal 100W magnitude amplification formed above optical signal, and amplification optical signal is projected measurement by collimation camera lens In target, enter step 5.

Step 5: launch light frequency to the narrow-linewidth single frequency laser of acousto-optic modulator through acousto-optic modulator Moving down and be used as local reference signal, the value moved down to meet the frequency of output heterodyne signal and just be respectively positioned on Frequency, enters step 6.

Acousto-optic modulator makes the value that local reference light frequency moves down:

When the laser instrument of use 1550nm wavelength is as light source, this car is static, and opponent vehicle is with 180km/h Speed away from this car time, the reflected signal frequency that laser radar receives moves down 64.5MHz；This car During with opponent vehicle all with 180km/h speed relative motion, the reflected signal frequency that laser radar receives Rate is by upper shifting 129MHz.In order to make output heterodyne signal frequency be respectively positioned in positive frequencies, this L.Lucidus Turcz. Examine signal frequency and at least move down 64.5MHz.If it addition, output heterodyne signal underfrequency, can draw Play amplitude output signal and change at random is occurred by phase effect.Such as, local reference signal and reception When signal is with frequency and quadrature in phase, amplitude output signal is zero, will be unable to measure distance and the speed of target Degree.Further, from the standpoint of the difficulty that acousto-optic modulator realizes, this laser radar apparatus can be selected for Acousto-optic modulator, moves down frequency 80MHz by this locality reference light, and the frequency of output heterodyne signal is positioned at Between 15.5MHz to 209MHz.

Step 6: local reference signal is mixed with receiving signal, exports heterodyne signal through optical-electrical converter, As shown in Figure 2.Calculate the correlation function of heterodyne signal and modulation code, correlation function peak value determine narrow The live width single-frequency laser flight time, and then obtain the distance of target, enter step 7.

Heterodyne signal and the calculating of modulation code correlation function:

The heterodyne signal of optical-electrical converter output is represented by:

Wherein E₁For local reference light power, E₂T () is for receiving signal light power, f_DRepresent receive light with Frequency difference between reference light.

Output signal is sampled with pulse width for the sampling period, the sampled data obtained and local modulation Correlation function calculated by yardage.

Step 7: signal processing unit module by calculating the correlation function of heterodyne signal and modulation code, Determined laser time of flight by correlation function peak, the distance of target can be calculated.Outside analysis The unequal interval data that difference signal sampling obtains, by unequal interval Fourier provided by the present invention frequency Spectral analysis method calculates the frequency of Doppler signal, can calculate the radial motion speed measuring target.

Unequal interval sampling signal frequency analysis method:

According to definition, Fourier transformation is:

$F\left(\mathrm{\ω}\right)=\underset{-\mathrm{\∞}}{\overset{\mathrm{\∞}}{\∫}}f\left(t\right)e^{-j\mathrm{\ω}t}dt---\left(1\right)$

Here f (t) is time-domain signal.In order to obtain the frequency spectrum of continuous signal on computers, it is necessary to first To continuous signal windowing.Assume that window function is a rectangular function being defined on [0, T] interval, amplitude Be 1, then formula (1) is transformed to:

$F\left(\mathrm{\ω}\right)=\underset{0}{\overset{T}{\∫}}f\left(t\right)e^{-j\mathrm{\ω}t}dt---\left(2\right)$

Integrating range is used N point sampling, formula (2) are transformed to following summation formula:

$F\left(\mathrm{\ω}\right)=\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}{\mathrm{\ΔT}}_i---\left(3\right)$

Here t_i、ΔT_i(i=0,1 ..., N-2) represent time location and the interval of sampled data points respectively [t_i,t_i+1] interval.If Δ T₁=Δ T₂=...=Δ T_N-2=Δ T, formula (3) just can transform to finite ordered The Fourier transformation of row:

$F\left(\mathrm{\ω}\right)=\mathrm{\Δ}T\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}=\frac{1}{F_s}\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}---\left(4\right)$

Here F_s=1/ Δ T represents sample rate.

In classical Digital Signal Processing, discrete Fourier transform is defined as:

$X\left(k\right)=\underset{n=0}{\overset{N-1}{\Σ}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}nk}---\left(5\right)$

Here k represents numerical frequency.

Relatively formula (4) and formula (5), can obtain:

t_i=t₀+nΔT (6)

$\begin{array}{cc}\mathrm{\ω}=2\mathrm{\π}f=2\mathrm{\π}(-\frac{1}{2}+\frac{k}{N})F_s& (k=0,1,...,N-1)\end{array}---\left(7\right)$

By formula (7) and formula (8), simulated time and simulation can be obtained according to digital value n and k Frequency.Therefore, when analogue signal equal interval sampling, fast Fourier transform method can be used to calculate The frequency spectrum of analogue signal.In order to make fast fourier transform algorithm can be used in unequal interval sampling simulation Signal, needs to do formula (3) form that suitable conversion is allowed to have formula (4):

$F\left(\mathrm{\ω}\right)=\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right){\mathrm{\ΔT}}_i{e}^{-{\mathrm{j\ωt}}_i}=\underset{i=0}{\overset{N-2}{\Σ}}\tilde{f}\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}---\left(8\right)$

HereThe heterodyne signal that amplitude is modulated, Δ T_iIt is between two 1 yard Time interval.The process that signal amplitude is multiplied by two 1 code interval is referred to as signal amplitude correction, warp The frequency that signal after amplitude correction just can directly use fast Fourier transform to complete heterodyne signal is divided Analysis.

The present invention will be described in citing in detail below:

Example one:

Modulation code width is set to 2ns, and signal length is 770ns, receives signal Doppler frequency and is 129MHz, calculates the correlation function of heterodyne signal and modulation code, observes correlation function peak value by Doppler Warbled impact, result is as shown by dotted lines in figure 3.In the case of equivalent signals peak power, directly The correlation function peak value that detection (receiving signal not modulated by Doppler frequency) exports is represented by solid line. Because the peak value that the mudulation effect of Doppler frequency makes output correlation function has declined, but it is noted that phase The dry detection local signal docking collection of letters number has amplification, and actually detected performance is an advantage over directly detecting.

Example two:

Distance detection performance is mainly determined by correlation function peak value, and the present embodiment investigates peak-peak with secondary Difference between peak value, difference shows that the most greatly noise robustness is the best.It addition, it is permissible from formula (9) Finding out, the heterodyne signal instantaneous power of output is by phase effect.The present embodiment investigate phase place from 0 to Between 2 π during change, correlation function peak value and the change of secondary peak, result is as shown in Figure 4.Receive signal Doppler frequency chooses tetra-representative values of 16MHz, 60MHz, 129MHz and 209MHz, is respectively positioned on In 15.5～209MHz interval ranges.Result shows the difference between peak-peak and minor peaks hardly Affected by phase place, shown that the randomness of reception time of arrival (toa) does not affect the detection of laser radar Can, therefore calculate heterodyne signal and can be used for distance detection with modulation code correlation function.

Example three:

The present embodiment inspection unequal interval sampled signal frequency spectrum analysis method is used for analyzing Doppler signal The feasibility of frequency.Choose tetra-representative values of 16MHz, 60MHz, 129MHz and 209MHz equally, Signal to four frequencies presses the sampling period sampling of modulation code width, and sampled data is pressed formula (8) Do amplitude correction, then use classical fast fourier transform algorithm that the data of amplitude correction are in Fu Leaf analysis, can obtain the frequency of Doppler signal, and analysis result is as shown in Figure 6.

The effect of embodiment and effect

According to mobile lidar distance speed measurement method involved by the present embodiment, narrow-linewidth single frequency swashs Light is pulse train, can improve the detection stability of laser radar, meets laser safety simultaneously and uses mark Accurate；Use single photoelectric detector on the one hand can improve the service efficiency receiving signal, on the other hand A beam splitter and an optical-electrical converter can be saved, reduce equipment cost；Pscudo-random codc modulation light The modulation of light source can be realized, compared to light frequency modulation, phase place by source amplitude by external modulation mode Modulation has advantage simple to operate, cheap；Pscudo-random codc modulation is used to launch light source amplitude, Need not insert cycle code in modulation code, make the coherence of modulation code be maintained, additionally improve The scope of tachometric survey, makes the velocity to moving target in road environment all can be detected；Use relevant The method of detection can amplify reception signal by local signal, has detection compared to directly detection sensitive Spend high advantage；After the heterodyne signal received is done simple amplitude correction, directly use in quick Fu The frequency of leaf transformation Algorithm Analysis heterodyne signal, has fast operation, a feature that noiseproof feature is good, And having special FFT hardware module to complete this work, system cost is low；It is operable with target-rich environment.

Above-mentioned embodiment is the preferred case of the present invention, is not intended to limit protection scope of the present invention.

Claims (8)

1. a mobile lidar distance speed measurement method, it is characterised in that including:

Step one, is driven laser instrument to produce amplitude continuous print narrow-linewidth single frequency laser by laser drive circuit；

Step 2, measures light defeated in the described narrow-linewidth single frequency laser that described laser instrument is exported by beam splitter Going out to electrooptic modulator, remaining reference light produces frequency shift (FS) by third contact of a total solar or lunar eclipse manipulator, for this locality As reference signal；

Step 3, local pulse-generating circuit generates pseudo noise code, and is driven institute by described pseudo noise code State the electrooptic modulator amplitude modulation(PAM) to described narrow-linewidth single frequency laser, it is thus achieved that the detection letter of laser radar Number；

Step 4, makes optical signal peak power amplify by erbium-doped fiber amplifier described detectable signal To 100W magnitude amplification formed above optical signal, and described amplification optical signal is projected by collimation camera lens To measuring in target；

Step 5, by described amplification optical signal and described reference signal mixing output heterodyne signal；

Step 6, calculates the correlation function of described heterodyne signal and modulation code, by described correlation function peak Value determines described narrow-linewidth single frequency laser time of flight, and then obtains the distance of target；And

Step 7, analyzes the unequal interval data that the sampling of described heterodyne signal obtains, obtains moving target The frequency of the Doppler signal produced, thus obtain the speed of described moving target.

Mobile lidar the most according to claim 1 distance speed measurement method, it is characterised in that:

Wherein, in described step 2, acousto-optic modulator produces the skew of frequency shift (FS) to local reference signal Value size with by negative frequency integral shift to positive frequencies as criterion, and described in low-limit frequency to meet One cycle of heterodyne signal is less than the length launching signal.

Mobile lidar the most according to claim 1 distance speed measurement method, it is characterised in that:

Wherein, described heterodyne signal is expressed as:

E₁For local reference light power,

E₂T () is reception signal light power,

f_DFor receiving the frequency difference between light and reference light,

Sampling described heterodyne signal with pulse width for the sampling period, the sampled data obtained is with described Modulation code calculates described correlation function.

Mobile lidar the most according to claim 1 distance speed measurement method, it is characterised in that:

Wherein, the sampling signal frequency analysis method of described unequal interval data:

According to Fourier transform formula:

$F\left(\mathrm{\ω}\right)=\underset{-\mathrm{\∞}}{\overset{\mathrm{\∞}}{\∫}}f\left(t\right)e^{-j\mathrm{\ω}t}dt---\left(1\right)$

Here f (t) is time-domain signal,

In order to obtain the frequency spectrum of continuous signal on computers, it is necessary to first to continuous signal windowing, it is assumed that Window function is a rectangular function being defined on [0, T] interval, and amplitude is 1, then formula (1) becomes It is changed to:

$F\left(\mathrm{\ω}\right)=\underset{0}{\overset{T}{\∫}}f\left(t\right)e^{-j\mathrm{\ω}t}dt---\left(2\right)$

Integrating range is used N point sampling, formula (2) are transformed to following summation formula:

$F\left(\mathrm{\ω}\right)=\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}{\mathrm{\ΔT}}_i---\left(3\right)$

t_iFor the time location of sampled data points,

ΔT_i(i=0,1 ..., N-2) it is interval [t_i,t_i+1] interval, if Δ T₁=Δ T₂=...=Δ T_N-2=Δ T, public Formula (4) just can transform to the Fourier transformation of finite sequence:

$F\left(\mathrm{\ω}\right)=\mathrm{\Δ}T\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}=\frac{1}{F_s}\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}---\left(4\right)$

F_s=1/ Δ T is sample rate,

In classical Digital Signal Processing, discrete Fourier transform is defined as:

$X\left(k\right)=\underset{n=0}{\overset{N-1}{\Σ}}x\left(n\right)e^{-j\frac{2\mathrm{\π}}{N}nk}---\left(5\right)$

K is numerical frequency,

Comparison expression (4) and formula (5), can obtain:

t_i=t₀+nΔT (6)

$\mathrm{\ω}=2\mathrm{\π}f=2\mathrm{\π}(-\frac{1}{2}+\frac{k}{N})F_s,(k=0,1,...,N-1)---\left(7\right)$

By formula (6) and formula (7), simulated time and simulation frequency can be obtained according to digital value n and k Rate, carries out the form that conversion is allowed to have formula (4) to formula (3):

$F\left(\mathrm{\ω}\right)=\underset{i=0}{\overset{N-2}{\Σ}}f\left(t_i\right){\mathrm{\ΔT}}_i{e}^{-{\mathrm{j\ωt}}_i}=\underset{i=0}{\overset{N-2}{\Σ}}\tilde{f}\left(t_i\right)e^{-{\mathrm{j\ωt}}_i}---\left(8\right)$

The described heterodyne signal that amplitude is modulated, Δ T_iIt is between two 1 yard Time interval.

Mobile lidar the most according to claim 4 distance speed measurement method, it is characterised in that:

Wherein, described formula (3) is carried out conversion be allowed to have the form of described formula (4) be for The fast fourier transform algorithm is made to can be used in unequal interval sampled analogue signals,

The process that signal amplitude is multiplied by two 1 code interval is referred to as signal amplitude correction, through amplitude correction After the signal frequency that just can directly use described fast Fourier transform to complete described heterodyne signal divide Analysis.

Mobile lidar the most according to claim 1 distance speed measurement method, it is characterised in that:

Wherein, described narrow-linewidth single frequency laser is pulse train, can put by using described Er-doped fiber Big device amplifies the peak power launching signal.

Mobile lidar the most according to claim 1 distance speed measurement method, it is characterised in that:

Wherein, described laser instrument is narrow-linewidth single frequency semiconductor laser.

Mobile lidar the most according to claim 1 distance speed measurement method, it is characterised in that:

Wherein, described beam splitter uses the described narrow linewidth list that described laser instrument is exported by 99:1 beam splitter In frequency laser, 99% measurement light exports electrooptic modulator, and remaining 1% produces frequency by third contact of a total solar or lunar eclipse manipulator Rate offsets, for locally as reference signal.