CN111650601B - High-resolution 3D imaging method and device for vehicle-mounted coherent laser radar - Google Patents
High-resolution 3D imaging method and device for vehicle-mounted coherent laser radar Download PDFInfo
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Abstract
The invention discloses a high-resolution 3D imaging method and a device for a vehicle-mounted coherent laser radar.A light beam is output to a target after being split and amplified, and an echo light beam of the target is received; the method comprises the steps of achieving 3D point cloud images of a target under an axial push-broom state through an MEMS two-dimensional scanner, obtaining 3D point cloud frame images at different moments, obtaining distance compensation amount of subsequent frame images relative to an initial frame image by combining relative speed of a radar platform and the target, then conducting distance compensation on each subsequent frame image, and combining the subsequent frame image with the initial frame image after compensation to obtain a final 3D point cloud image. The invention can equivalently improve the vertical scanning line number and the vertical angular resolution of the MEMS two-dimensional scanner and realize 3D high-resolution imaging.
Description
Technical Field
The invention relates to the technical field of laser radars, in particular to a high-resolution 3D imaging method and device for a vehicle-mounted coherent laser radar.
Background
Lidar provides the necessary 3D point cloud data for the unmanned vehicle. Currently, the vehicle-mounted lidar scanning modes mainly include mechanical scanning and micro-electro-mechanical system (MEMS) scanning. The laser scanning lines can be divided into single line laser radars and multi-line laser radars, such as 4-line laser radars, 8-line laser radars, 16-line laser radars, 32-line laser radars and 64-line laser radars. Compared with a single-line laser radar, the multi-line laser radar has the advantages of large data volume, high detection precision, long detection distance, wide range and the like. The mechanical scanning is based on a well-established rotating mirror, capable of employing mechanical rotation in the horizontal direction and non-mechanical optical scanning in the vertical direction by stacking, the vertical angular resolution of which is determined by the spacing between two adjacent modules and the focal length of the optical system. In order to improve the vertical angular resolution under the limited scanning line number, the on-line mechanical scanning laser radar adopts a non-uniform distribution scheme with a dense middle and two sparse sides, such as a cereal stopper Pandar40, a beam 1 to a beam 6, and the vertical angular resolution between two adjacent lines is 1 degree; beam 6 to beam 30, with a vertical angular resolution of 0.33 degrees between two adjacent lines; from beam 30 to beam 40, the vertical angular resolution between two adjacent lines is 1 degree, which enables the most dense scanning directly in front of the most important. However, the proposal requires the lasers to be longitudinally and densely arranged, not only has large size and high cost, but also has high requirements on heat dissipation, process and the like.
The laser radar based on MEMS scanning can directly integrate a micro-vibration mirror with very exquisite volume on a silicon-based chip, changes the emission angle of a single emitter through the vibration of the micro-vibration mirror to scan, realizes micron-sized area array scanning, and cannot see any mechanical rotating part in the LiDAR in macroscopical view. MEMS scanning technology simple structure, size are little, because do not need the rotating part, can compress the structure and the size of radar greatly, improve life to and advantages such as low cost, easy volume production, easy embedding automobile body. Therefore, MEMS scanning technology is an innovation of conventional mechanical LiDAR, leading to miniaturization and cost reduction of LiDAR. The vertical angle resolution of the prior MEMS scanning vehicle-mounted laser radar can reach 0.1 degrees, the vertical angle resolution of the radium intelligence LS20E MEMS scanning laser radar can reach 0.05 degrees, the scanning effect is equivalent to a 400-line mechanical laser radar, and the detection distance can reach 500 meters. In addition, the MEMS scanning technology can dynamically adjust the scanning mode to focus on a specific object, collect detailed information of objects farther away and smaller, and identify them. These are all what conventional mechanical lidar cannot achieve. However, since the MEMS scanning frame frequency and the display frame frequency are consistent, and the scanning frame frequency must be correspondingly increased to increase the display frame frequency, but the implementation of controllable high-frequency vibration of the micro-galvanometer is difficult, the requirement on hardware is high, and the cost is high, so that the MEMS scanning lidar has become a bottleneck that troubles the development of the MEMS scanning lidar.
Disclosure of Invention
The invention aims to provide a high-resolution 3D imaging method and device for a vehicle-mounted coherent laser radar. The invention can equivalently improve the scanning line number and the vertical angular resolution of the MEMS two-dimensional scanner by utilizing the relative motion between the radar platform and the target on the premise of not increasing the hardware complexity, realizes 3D high-resolution imaging and has good development prospect in the field of vehicle-mounted laser radars.
The technical scheme of the invention is as follows: in the high-resolution 3D imaging method of the vehicle-mounted coherent laser radar, a linear frequency modulation continuous wave laser light source in a radar platform generates an output light beam which is divided into a local oscillation light beam and an emission light beam by a 1 multiplied by 2 beam splitter; amplifying the emission light beam, transmitting the amplified emission light beam to a target and receiving an echo light beam of the target, carrying out coherent light frequency mixing on the echo light beam and a local oscillator light beam through an optical bridge, obtaining an intermediate frequency signal containing target distance and speed information by adopting balanced receiving, carrying out filtering processing and sampling processing on the intermediate frequency signal to obtain sampling data, and carrying out real-time parallel fast Fourier transform and cross spectrum processing on the obtained sampling data by using a field programmable gate array to realize parallel synchronous measurement of the target distance and the radar platform speed; and then, utilizing the relative motion between the radar platform and the target, realizing the 3D point cloud image of the target in an axial push-broom state by the MEMS two-dimensional scanner, obtaining 3D point cloud frame images at different moments, obtaining the distance compensation quantity of the subsequent frame image relative to the initial frame image by combining the relative motion speed between the radar platform and the target, then performing distance compensation on each subsequent frame image, and combining each subsequent frame image with the initial frame image after compensation to obtain the finally displayed 3D point cloud image.
According to the vehicle-mounted coherent laser radar high-resolution 3D imaging method, the distance compensation quantity of the subsequent frame image relative to the initial frame image is obtained by combining the radar platform speed, then the distance compensation is carried out on each frame image, and each frame image is combined with the initial frame image after the compensation to obtain the finally displayed 3D point cloud image, specifically: firstly, establishing an initial position coordinate system of a radar platform to obtain an initial position coordinate of a target, then measuring the relative speed between the radar platform and the target along with the movement of the radar platform, obtaining a radar platform position coordinate system at different moments and a position coordinate of the target in the coordinate system by calculating an integral so as to obtain a coordinate approximate relation between an initial frame image and subsequent frame images at different moments, then obtaining a distance compensation amount of the subsequent frame images relative to the initial frame image according to the coordinate approximate relation, then performing distance compensation on each frame image, merging each frame image and the initial frame image after compensation to obtain a space point set of the target coordinate, wherein the space point set is a finally displayed 3D point cloud image.
According to the high-resolution 3D imaging method of the vehicle-mounted coherent laser radar, a laser light source in a radar platform is a narrow-linewidth linear frequency modulation continuous wave laser light source, a generated output light beam is a frequency linearly modulated continuous coherent laser, symmetrical triangular wave linear modulation is adopted, the frequency of a modulation signal changes in a symmetrical triangular shape along with time, in one period, the first half part is positive frequency modulation, and the second half part is negative frequency modulation;
the light field of the output beam is represented as:
wherein t is time, E 0 Is the amplitude, T is the frequency modulation period, f 0 In order to frequency-modulate the initial frequency,
for the frequency modulation rate, B is the bandwidth of the modulation band, phi up (n) is the initial phase of the rising segment of the nth output beam frequency modulation pulse phi down (n) is the initial phase of the falling segment of the nth output beam chirp, exp is an exponential function with a natural constant e as the base,
according to the high-resolution 3D imaging method for the vehicle-mounted coherent laser radar, the output light beam is polarized by the polarizer, the polarization degree is improved, the output light beam is split by the 1X 2 beam splitter, a small part of energy is used as a local oscillation light beam, and the local oscillation light beam is time delay tau L The optical field of the local oscillator beam is expressed as:
wherein E is L Is the local oscillator beam amplitude, phi LO Is the noise phase of the local oscillator beam;
most energy is used as a transmission beam, the transmission beam is amplified and then passes through a space optical circulator, then is transmitted to a target through an MEMS two-dimensional scanner and an optical telescope, and an echo beam of the target is received by the optical telescope, wherein the echo beam is time delay tau S Represented as:
wherein E is S Is the amplitude of the echo beam, phi S Is the noise phase of the echo beam;
the optical field after the echo light beam and the local oscillator light beam of the target are combined is expressed as:
time delay tau of an echo beam S Time delay tau from local oscillator beam L The relationship of (c) is expressed as:
wherein c is the speed of light, R is the distance between the radar platform and the target, V is the radial speed of the relative movement between the radar platform and the target, and f Doppler Doppler frequency shift caused by the relative motion radial velocity of the radar platform and the target;
the four outputs of the echo light beam and the local oscillator light beam after being mixed by the 2 × 4 90-degree optical bridge are respectively:
wherein phi is N-n Is the nth output beam mixing noise phase, I S Is a direct current quantity related to the echo beam; i is o Is the direct current quantity related to the local oscillator beam;
the in-phase signal and the orthogonal signal which are output by the optical bridge connector and have the orthogonal characteristic are respectively received by a photoelectric balance detector, and an intermediate frequency signal containing target distance and speed information is obtained; in the intermediate frequency signal of the forward frequency modulation process, the in-phase signal and the quadrature signal are respectively as follows:
in the intermediate frequency signal of the negative direction frequency modulation process, the in-phase signal and the orthogonal signal are respectively as follows:
wherein k is in Is the response rate, k, of a photoelectric balanced detector receiving in-phase signals qu Is the response rate, phi, of a photoelectric balance detector receiving an orthogonal signal i-n And phi q-n Noise phases of the in-phase signal and the quadrature signal, respectively;
the amplitudes of the in-phase and quadrature channels are replaced by:
the in-phase signal and the quadrature signal in the intermediate frequency signal in the forward frequency modulation process are simplified as follows:
in-phase signals and orthogonal signals in intermediate frequency signals in the negative direction frequency modulation process are simplified as follows:
the in-phase signal and the orthogonal signal are respectively subjected to analog-to-digital conversion through an analog-to-digital converter, and then are acquired by a field programmable gate array to be subjected to parallel fast Fourier transform, wherein the Fourier transform of the in-phase signal is represented as follows:
the orthogonal signal fourier transform is represented as:
performing cross-spectrum processing on the two channels:
wherein * Represents a conjugation;
finally, only the imaginary part is taken to obtain
Img＝δ 2 (f-f n )-δ 2 (f+f n )，
The frequency values in the positive frequency modulation process and the negative frequency modulation process can be respectively obtained by extracting the position and the positive and negative of the frequency spectrum peak value through a gravity center method:
from the above formula, one can obtain:
in the above formula, f n-up Is the value of the intermediate frequency in the forward frequency modulation process, f n-down Is the value of the intermediate frequency in the negative frequency modulation process, f Doppler Doppler frequency shift caused by the relative motion radial velocity of the radar platform and the target;
because the Doppler frequency is in direct proportion to the relative movement speed of the radar platform and the target, the positive and negative Doppler frequency shifts are related to the direction of the radial relative movement speed, the positive frequency shift represents that the radar platform and the target move in the opposite direction, and the negative frequency shift represents that the radar platform and the target move in the opposite direction. Therefore, the magnitude and the direction of the relative motion radial velocity of the radar platform and the target can be obtained by Doppler frequency shift, and the magnitude and the direction of the relative motion radial velocity of the radar platform and the target can be obtained by Doppler frequency shift and are expressed as
Where λ is the output beam wavelength, f Doppler Doppler frequency shift caused by the relative motion radial speed of the radar platform and the target;
the distance to the target point is obtained from the above equation:
According to the vehicle-mounted coherent laser radar high-resolution 3D imaging method, the MEMS two-dimensional scanner realizes 3D point cloud images of targets in an axial push scanning state, specifically, the MEMS two-dimensional scanner adopts line-by-line scanning, light spots reflected by micro-reflectors in the MEMS two-dimensional scanner do sawtooth wave or triangular wave motion in the vertical direction and do simple harmonic motion in the horizontal direction to form a scanning light spot array, the scanning angle of the MEMS two-dimensional scanner in the vertical direction is theta, and the scanning angle range of the MEMS two-dimensional scanner in the vertical direction is theta
The vertical angular resolution is determined by the beam divergence angle delta theta in the vertical direction, and thus the number of scan lines in the vertical direction
The distance between the plane of the radar platform and the target plane is L m Wherein the scan array of the initial frame image is denoted by subscript m, then the period of the number of vertical scan lines is:
the distance between the plane of the radar platform and the target plane is L when the radar platform moves forward m+k And get mFor a scan array of + k frames of images, the period of the vertical scan line is:
in the high-resolution 3D imaging method of the vehicle-mounted coherent laser radar, the initial position of the radar platform is used as the origin of coordinates O m Through O m And a point O on the target plane m+1 Establishing Z m Axes, establishing a stationary coordinate system X in the right-hand rule m Y m Z m O m (ii) a Using O as the origin of coordinates of the target coordinate system, passing through the origin of coordinates O and using Z m Establishing a coordinate axis Z in the positive direction, and establishing a static coordinate system XYZO for the target position according to the right-hand rule; after 1 frame of scanning time delta T, the motion coordinate system where the radar platform is located has the speed V m Move to X m+1 Y m+1 Z m+1 O m+1 Wherein the origin of coordinates O m+1 Is the real-time position of the moving state of the radar platform,
coordinate system X at initial position of radar platform m Y m Z m O m By the obtained target P distance R m And radar platform velocity V m Azimuth angle epsilon of the radiation beam m Angle of pitch η of the emitted beam m Thus the coordinates (x) of the target P in the coordinate system P_m ,y P_m ,z P_m ) Expressed as:
in the radar platform position coordinate system X m+1 Y m+1 Z m+1 O m+1 By the obtained target P distance R m+1 And radar platform velocity V m+1 Azimuth angle epsilon of the radiation beam m+1 Angle of pitch η of the emitted beam m+1 Thus the coordinates (x) of the target P in the coordinate system P_m+1 ,y P_m+1 ,z P_m+1 ) Expressed as:
since the time interval Δ T between the m-th frame and the m + 1-th frame is short, V m ΔT＜＜R m The following approximate relationship is obtained:
by analogy, the coordinate approximation relation of the target P between the m + k-1 th frame and the m + k th frame is as follows:
finally, the coordinate approximation relation of the target P between the mth frame and the m + k frame can be obtained:
therefore, on one hand, the relative speed between the radar platform and the target is measured, the integration is carried out to obtain the position coordinate system of the radar platform and the coordinates of the target in the coordinate system at different moments, so as to obtain the distance compensation quantity of the subsequent m +1 frame, … … m + k frame point cloud image relative to the initial frame image, and then the distance compensation, namely the inter-frame compensation, is carried out on each frame image;
on the other hand, the relative speed V between the radar platform and the target is kept constant within the scanning duration delta tau of each frame, the number of scanning points of each frame is M, and the duration period of each scanning point is
No compensation at 1 st point and compensation at 2 nd point
3 rd point compensation
… … Mth point compensation
Namely, the intra-frame compensation of each frame of image is realized;
after compensation, combining each frame image with the initial frame image, and acquiring a space point set of target coordinates within a certain time period tau = (k + 1) Δ T from the m-th frame to the m + k-th frame:
the space point set sigma P is the finally displayed 3D point cloud image.
The device of the vehicle-mounted coherent laser radar high-resolution 3D imaging method is characterized in that: the linear frequency modulation continuous wave laser device comprises a linear frequency modulation continuous wave laser light source, wherein the output end of the linear frequency modulation continuous wave laser light source is sequentially connected with a polarizer and a 1 x 2 beam splitter, and the 1 x 2 beam splitter is connected with an optical circulator;
the output end of the optical circulator is sequentially connected with an MEMS two-dimensional scanner and an optical telescope; the optical circulator and the 1 x 2 beam splitter are connected with an optical bridge together; the output end of the optical bridge is sequentially connected with a photoelectric balance detector, an analog-to-digital converter and a field programmable gate array, and the output end of the field programmable gate array is connected with a main control computer; the main control computer is also connected with the MEMS two-dimensional scanner.
Compared with the prior art, the output light beam generated by the linear frequency modulation continuous wave laser light source in the radar platform is divided into the local oscillation light beam and the emission light beam by the 1 multiplied by 2 beam splitter; amplifying the emitted light beam, then emitting the amplified light beam to a target and receiving an echo light beam of the target, carrying out coherent light mixing on the echo light beam and a local oscillator light beam through an optical bridge, obtaining an intermediate frequency signal containing target distance and speed information by adopting balanced receiving, carrying out filtering processing and sampling processing on the intermediate frequency signal to obtain sampling data, and carrying out real-time parallel fast Fourier transform and cross spectrum processing on the obtained sampling data by using a field programmable gate array to realize parallel synchronous measurement of the target distance and the speed of a radar platform; and then, utilizing the relative motion between the radar platform and the target, realizing the 3D point cloud image of the target in an axial push-broom state by an MEMS two-dimensional scanner, obtaining 3D point cloud frame images at different moments, obtaining the distance compensation quantity of the subsequent frame image relative to the initial frame image by combining the relative speed of the radar platform and the target, then performing distance compensation on each subsequent frame image, and combining each frame image with the initial frame image after compensation to obtain the finally displayed 3D point cloud image. Compared with the traditional single-frame image, the vertical scanning line number and the vertical resolution of the obtained 3D point cloud image can be improved by multiple times, so that 3D high-resolution imaging can be realized on the premise of not increasing the hardware complexity, and the target distance and the radar platform speed can be obtained without an external speed sensor, so that the integration miniaturization is facilitated, the complexity of a system is reduced, the volume of the whole device is reduced, and the advantages of small volume, light weight, high resolution, high precision and the like are achieved. The invention has good development prospect in the field of vehicle-mounted laser radars.
Drawings
Fig. 1 is a schematic structural view of the present invention.
FIG. 2 is a schematic diagram showing a waveform relationship and a frequency difference between a symmetric triangular chirp continuous wave echo beam and a local oscillator beam;
FIG. 3 is a schematic diagram of a waveform relationship between symmetric triangular chirp continuous waves of different output light beams;
FIG. 4 is a laser radar push-broom imaging coordinate system;
FIG. 5 is a schematic scan line view for a 150 meter pedestrian;
FIG. 6 is a comparison image of a 3D point cloud imaging of a target hemispherical target at a distance of 300 meters.
The labels in the figures are: 1. a laser light source; 2. a polarizer; 3. a 1 × 2 beam splitter; 4. An optical circulator; 5. a MEMS two-dimensional scanner; 6. an optical telescope; 7. an optical bridge; 8. a photoelectric balance detector; 9. a field programmable gate array; 10. and (5) a master control computer.
Detailed Description
The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.
Example 1: in the high-resolution 3D imaging method of the vehicle-mounted coherent laser radar, a linear frequency modulation continuous wave laser light source in a radar platform generates an output light beam which is divided into a local oscillation light beam and an emission light beam through a 1 multiplied by 2 beam splitter; amplifying the emission light beam, transmitting the amplified emission light beam to a target and receiving an echo light beam of the target, carrying out coherent light frequency mixing on the echo light beam and a local oscillator light beam through an optical bridge, obtaining an intermediate frequency signal containing target distance and speed information by adopting balanced receiving, carrying out filtering processing and sampling processing on the intermediate frequency signal to obtain sampling data, and carrying out real-time parallel fast Fourier transform and cross spectrum processing on the obtained sampling data by using a field programmable gate array to realize parallel synchronous measurement of the target distance and the speed of a radar platform; and then utilizing the relative motion between the radar platform and the target, realizing the 3D point cloud image of the target under the axial push-broom state by the MEMS two-dimensional scanner, obtaining the 3D point cloud frame images at different moments, obtaining the compensation quantity of the subsequent frame image relative to the initial frame image by combining the relative speed between the radar platform and the target, then compensating each subsequent frame image, and merging each subsequent frame image and the initial frame image after compensation to obtain the finally displayed 3D point cloud image. The device for realizing the method comprises a laser light source 1, wherein the output end of the laser light source 1 is sequentially connected with a polarizer 2 and a 1 × 2 beam splitter 3, and the 1 × 2 beam splitter 3 is connected with an optical circulator 4;
the output end of the optical circulator 4 is sequentially connected with an MEMS two-dimensional scanner 5 and an optical telescope 6; the optical circulator 4 and the 1 x 2 beam splitter 3 are connected with an optical bridge 7; the output end of the optical bridge 7 is sequentially connected with a photoelectric balance detector 8, an analog-digital converter 11 and a field programmable gate array 9, and the output end of the field programmable gate array 9 is connected with a main control computer 10; the host computer 10 is also connected to the MEMS two-dimensional scanner 5.
Example 2: a high-resolution 3D imaging method of a vehicle-mounted coherent laser radar is shown in figure 1 and comprises a laser light source 1, wherein the laser light source 1 adopts a 1550nm single-mode narrow-linewidth continuous optical fiber laser safe to human eyes, the linewidth of the laser is 10kHz, the output power is 20mW, and the optical fiber output has isolation protection; the frequency-modulated laser phase modulator is driven to generate frequency-modulated laser signals by adopting a frequency-modulated signal generated by a frequency-modulated signal generator and a frequency-mixed signal of a fundamental frequency signal generated by a fundamental frequency signal generator as driving signals of the optical fiber phase modulator, harmonic waves are suppressed by an optical filter to keep the frequency-modulated laser signals of required orders, the frequency-modulated bandwidth is 5GHz, the frequency-modulated rate is 5PHz/s, the frequency-modulated period is 2 mu s, the repetition frequency is 500kHz, namely 50 ten thousand chirp pulses are emitted per second; the optical fiber phase modulator generates an output light beam, firstly, the output light beam is linearly modulated by adopting symmetrical triangular waves, the frequency of a modulation signal changes in a symmetrical triangular shape along with time, in a period, the front half part is positively modulated in frequency, and the rear half part is negatively modulated in frequency;
the light field of the output beam is represented as:
wherein t is time, E 0 Is the amplitude, T is the frequency modulation period, f 0 In order to frequency-modulate the initial frequency,
for the frequency modulation rate, B is the bandwidth of the modulation band, phi up (n) is the initial phase of the rising segment of the nth output beam frequency modulation pulse phi down (n) is the initial phase of the falling portion of the nth output beam chirp, exp is an exponential function with a natural constant e as the base,
polarizing by a polarizer to ensure that the polarization extinction ratio is greater than 25dB, splitting by a 1X 2 beam splitter, outputting two paths of light intensity of 1 L The optical field of the local oscillator beam is represented as:
wherein E is L Is the local oscillator beam amplitude, phi LO Is the noise phase of the local oscillator beam;
most of the energy is used as the emission beam; the emitted light beam is amplified to 300mW by an erbium-doped fiber amplifier and then emitted to a target by an MEMS two-dimensional scanner and an optical telescope, the effective caliber of the MEMS two-dimensional scanner is 3mm, the far field emission angle is about 1mrad, line-by-line scanning is adopted, a slow axis triangular wave in the vertical direction, a fast axis resonance in the horizontal direction is adopted, the scanning angle in the vertical direction is 5.73 degrees, the number of scanning lines is 100 lines, the frame frequency is 10Hz, and the optical telescope receives an echo light beam of the target, wherein the echo light beam is time delay tau S Represented as:
wherein E is S Is the amplitude of the echo beam, phi S Is the noise phase of the echo beam;
the optical field after the echo light beam and the local oscillator light beam of target are closed is expressed as:
time delay tau of an echo beam S Time delay tau from local oscillator beam L The relationship of (c) is expressed as:
where c is the speed of light, R is the distance of the target, V is the radial velocity of the relative motion of the radar platform and the target, and f Doppler Is the Doppler shift caused by the relative motion radial velocity of the radar platform and the target,
the four outputs of the echo light beam and the local oscillator light beam after being mixed by the 2 × 4 90-degree optical bridge are respectively:
wherein phi is N-n Is the nth output beam mixing noise phase, I s Is a direct current quantity related to the echo beam; I.C. A o Is the direct current quantity related to the local oscillator beam;
the in-phase signal and the orthogonal signal with the orthogonal characteristic output by the optical bridge are respectively received by a photoelectric balance detector, the bandwidth is 100MHz, and the in-phase signal and the orthogonal signal are subjected to alternating current coupling to obtain an intermediate frequency signal containing target distance and speed information; the same phase signal and the orthogonal signal in the intermediate frequency signal in the forward frequency modulation process are respectively as follows:
in the intermediate frequency signal of the negative direction frequency modulation process, the in-phase signal and the orthogonal signal are respectively as follows:
wherein k is in Is the response rate, k, of a photoelectric balanced detector receiving in-phase signals qu Is the response rate, phi, of a photoelectric balance detector receiving an orthogonal signal i-n And phi q-n Noise phases of the in-phase signal and the quadrature signal, respectively;
the amplitudes of the in-phase and quadrature channels are replaced by:
the in-phase signal and the orthogonal signal in the intermediate frequency signal in the forward frequency modulation process are simplified as follows:
in-phase signals and orthogonal signals in intermediate frequency signals in the negative direction frequency modulation process are simplified as follows:
the in-phase signal and the orthogonal signal are respectively subjected to analog-to-digital conversion by an analog-to-digital converter, and then are collected by a field programmable gate array to be subjected to parallel fast Fourier transform, wherein the Fourier transform of the in-phase signal is represented as follows:
the orthogonal signal fourier transform is represented as:
performing cross-spectrum processing on the two channels:
wherein * Represents a conjugation;
finally, only the imaginary part is taken to obtain
Img＝δ 2 (f-f n )-δ 2 (f+f n )，
The frequency values in the positive frequency modulation process and the negative frequency modulation process can be respectively obtained by extracting the position and the positive and negative of the frequency spectrum peak value through a gravity center method:
from the above formula one can obtain:
in the above formula, f n-up Is the value of the intermediate frequency in the forward frequency modulation process, f n-down Is the intermediate frequency value, f, in the negative direction frequency modulation process Doppler Doppler frequency shift caused by the relative motion radial velocity of the radar platform and the target;
because the Doppler frequency is in direct proportion to the relative movement speed of the radar platform and the target, the positive and negative Doppler frequency shifts are related to the direction of the radial speed of the relative movement, the positive frequency shift represents that the radar platform and the target move in the opposite direction, and the negative frequency shift represents that the radar platform and the target move in the opposite direction. Therefore, the magnitude and the direction of the relative motion radial velocity of the radar platform and the target can be obtained by Doppler frequency shift, and the magnitude and the direction of the relative motion radial velocity of the radar platform and the target can be obtained by Doppler frequency shift and are expressed as
Where λ is the output beam wavelength, f Doppler Doppler frequency shift caused by the relative motion radial speed of the radar platform and the target;
the distance to the target point is obtained from the above equation:
Compared with the axial push-broom movement distance, the size of the laser radar platform can beNeglecting the laser radar, abstracting the laser radar to a point, and completing the corresponding time synchronization between the MEMS two-dimensional scanner and the laser radar, as shown in fig. 3, the MEMS two-dimensional scanner adopts line-by-line scanning, the light spot reflected by the micro-mirror in the MEMS two-dimensional scanner makes triangular wave motion in the vertical direction and simple harmonic motion in the horizontal direction to form a scanning light spot array, the vertical direction scanning angle of the MEMS two-dimensional scanner is θ, and the vertical direction scanning angle range is
The vertical angular resolution is determined by the beam divergence angle delta theta in the vertical direction, and thus the number of scan lines in the vertical direction
The distance between the plane of the radar platform and the target plane is L m Wherein the scan array of the initial frame image is denoted by subscript m, then the period of the number of vertical direction scan lines is:
the distance between the plane of the radar platform and the target plane is L along with the advance of the radar platform m+k And obtaining a scanning array of the m + k frame image, wherein the period of the scanning line in the vertical direction is as follows:
establishing a laser radar push-broom imaging coordinate system as shown in FIG. 4: using the initial position of radar platform as the origin of coordinates O m Through O m And a point O on the target plane m+1 Establishing Z m Axis, establishing a stationary coordinate system X in the right-hand rule m Y m Z m O m (ii) a Using O as the origin of coordinates of the target coordinate system, passing through the origin of coordinates O and using Z m Establishing a coordinate axis Z in the positive direction, and establishing a static coordinate system XYZO for the target position according to the right-hand rule; over a 1 frame scan timeAfter delta T, the motion coordinate system where the radar platform is located takes the speed as V m Move to X m+1 Y m+1 Z m+1 O m+1 Wherein the origin of coordinates O m+1 Is the real-time position of the radar platform moving state,
coordinate system X at initial position of radar platform m Y m Z m O m By the obtained target P distance R m And radar platform velocity V m Azimuth angle epsilon of the radiation beam m Angle of pitch η of the emitted beam m Thus the coordinates (x) of the target P in the coordinate system P_m ,y P_m ,z P_m ) Expressed as:
in radar platform position coordinate system X m+1 Y m+1 Z m+1 O m+1 By the obtained target P distance R m+1 And radar platform velocity V m+1 Azimuth angle epsilon of the radiation beam m+1 Angle of pitch η of the emitted beam m+1 Thus the coordinates (x) of the target P in the coordinate system P_m+1 ,y P_m+1 ,z P_m+1 ) Expressed as:
since the time interval Δ T between the m-th frame and the m + 1-th frame is short, V m ΔT＜＜R m The following approximate relationship is obtained:
by analogy, the coordinate approximation relation of the target P between the m + k-1 th frame and the m + k th frame is as follows:
finally, the coordinate approximation relation of the target P between the mth frame and the m + k frame can be obtained:
therefore, on one hand, the relative speed between the radar platform and the target is measured, the integration is carried out to obtain the position coordinate system of the radar platform and the coordinates of the target in the coordinate system at different moments, so as to obtain the distance compensation quantity of the subsequent m +1 frame, … … m + k frame point cloud image relative to the initial frame image, and then the distance compensation, namely the inter-frame compensation, is carried out on each frame image;
on the other hand, considering that the relative speed V between the radar platform and the target is kept constant within the scanning duration delta tau of each frame, the number of scanning points of each frame is M, and the duration period of each scanning point is
No compensation at 1 st point and compensation at 2 nd point
3 rd point compensation
… … Mth point compensation
Namely, the intra-frame compensation of each frame of image is realized;
after compensation, combining each frame image with the initial frame image to obtain a spatial point set of target coordinates within a certain time period tau = (k + 1) delta T from the mth frame to the m + k frame:
the space point set sigma P is a finally displayed 3D point cloud image and is presented by a main control computer;
in this embodiment, the distance between the laser radar platform and the target is 300m, the period of the scanning line in the vertical direction is 0.3 m, the instantaneous relative movement speed of the laser radar platform and the target is 30 m/s, and the directions are opposite to each other, so as to obtain the 1 st frame of point cloud picture. The laser radar platform is propelled for 3 meters at a constant speed within 1 frame time (0.1 second), and the main control computer finishes the acquisition of the point cloud of the 2 nd frame and interframe compensation; the 2 frames of point clouds are subjected to intra-frame compensation, and then the 2 frames of point clouds are combined, so that the scanning line number in the vertical direction can be equivalently improved by 1 time, and the resolution in the vertical direction can be improved by 1 time. The applicant also performs 3D point cloud imaging on the actual object, and fig. 5 shows a schematic diagram of scanning lines for a pedestrian of 150 meters, with a single-frame scanning line array on the left and a 2-frame combined scanning line array on the right. Fig. 6 shows a true 3D map (a) of a target hemispherical target at a distance of 300 meters, a 3D point cloud image (b) of the lidar before compensation, and a 3D point cloud image (c) of the lidar after compensation according to the present invention. As is apparent from fig. 5 and 6, the present invention can equivalently improve the scanning line number and vertical angular resolution of the MEMS two-dimensional scanner, thereby realizing 3D high resolution imaging.
In conclusion, the invention can realize the parallel synchronous measurement of the target distance and the radar platform speed, and utilize the relative motion between the radar platform and the target to obtain the frame images in the 3D point cloud images at different moments and compensate the frame images, and each frame image is combined with the initial frame image after compensation. In addition, the invention can obtain the target distance and the relative speed of the radar platform without an external speed sensor, thereby being beneficial to the integration miniaturization, reducing the complexity of the system and the volume of the whole device, and having the advantages of small volume, light weight, high resolution, high precision and the like. The invention has good development prospect in the field of vehicle-mounted laser radars.
Claims (7)
1. The high-resolution 3D imaging method of the vehicle-mounted coherent laser radar is characterized by comprising the following steps of: an output light beam generated by a linear frequency modulation continuous wave laser light source in the radar platform is divided into a local oscillation light beam and an emission light beam by a 1 multiplied by 2 beam splitter; amplifying the emission light beam, transmitting the amplified emission light beam to a target and receiving an echo light beam of the target, carrying out coherent light frequency mixing on the echo light beam and a local oscillator light beam through an optical bridge, obtaining an intermediate frequency signal containing target distance and speed information by adopting balanced receiving, carrying out filtering processing and sampling processing on the intermediate frequency signal to obtain sampling data, and carrying out real-time parallel fast Fourier transform and cross spectrum processing on the obtained sampling data by using a field programmable gate array to realize parallel synchronous measurement of the target distance and the speed of a radar platform; and then, utilizing the relative motion between the radar platform and the target, realizing the 3D point cloud image of the target in an axial push-broom state by the MEMS two-dimensional scanner, obtaining 3D point cloud frame images at different moments, obtaining the distance compensation quantity of the subsequent frame image relative to the initial frame image by combining the relative motion speed between the radar platform and the target, then performing distance compensation on each subsequent frame image, and combining each subsequent frame image with the initial frame image after compensation to obtain the finally displayed 3D point cloud image.
2. The vehicle-mounted coherent lidar high-resolution 3D imaging method according to claim 1, wherein: the method comprises the following steps of obtaining the distance compensation amount of a subsequent frame image relative to an initial frame image by combining the relative movement speed between a radar platform and a target, then performing distance compensation on each frame image, merging each frame image with the initial frame image after compensation, and obtaining a finally displayed 3D point cloud image, wherein the method specifically comprises the following steps: firstly, establishing an initial position coordinate system of a radar platform to obtain an initial position coordinate of a target, then measuring the relative speed between the radar platform and the target along with the movement of the radar platform, obtaining the radar platform position coordinate systems at different moments and the position coordinate of the target in the coordinate system by calculating an integral so as to obtain the coordinate approximate relation between an initial frame image and subsequent frame images at different moments, then obtaining the distance compensation quantity of the subsequent frame images relative to the initial frame image according to the coordinate approximate relation, then performing distance compensation on each frame image, merging each frame image and the initial frame image after compensation to obtain a space point set of the target coordinate, wherein the space point set is a finally displayed 3D point cloud image.
3. The vehicle-mounted coherent lidar high-resolution 3D imaging method according to claim 1, wherein: the laser light source in the radar platform is a narrow-linewidth linear frequency modulation continuous wave laser light source, the generated output light beam is continuous coherent laser with linearly modulated frequency, symmetrical triangular wave linear modulation is adopted, the frequency of a modulation signal changes in a symmetrical triangular mode along with time, in a period, the front half part is in positive frequency modulation, and the rear half part is in negative frequency modulation;
the light field of the output beam is expressed as:
wherein t is time, E 0 Is the amplitude, T is the frequency modulation period, f 0 In order to frequency-modulate the initial frequency,
for the frequency modulation rate, B is the bandwidth of the modulation band, phi up (n) is the initial phase of the rising segment of the frequency-modulated pulse of the nth output beam, phi down (n) is the initial phase of the falling portion of the nth output beam chirp, exp is an exponential function with a natural constant e as the base,
4. the vehicle-mounted coherent lidar high-resolution 3D imaging method according to claim 3, wherein: the output light beam is polarized by a polarizer to improve the polarization degree, and then is split by a 1X 2 beam splitter, a small part of energy is used as a local oscillation light beam, and the local oscillation light beam is time delay tau L The optical field of the local oscillator beam is expressed as:
wherein E is L Is the local oscillator beam amplitude, phi LO Is the noise phase of the local oscillator beam;
most energy is used as a radiation beam, the radiation beam passes through the space optical circulator after being amplified, then is transmitted to a target through the MEMS two-dimensional scanner and the optical telescope, and an echo beam of the target is received by the optical telescope, wherein the echo beam is time delay tau S Expressed as:
wherein, E S Is the amplitude of the echo beam, phi S Is the noise phase of the echo beam;
the optical field after the echo light beam and the local oscillator light beam of the target are combined is expressed as:
time delay tau of an echo beam S Time delay tau from local oscillator beam L The relationship of (c) is expressed as:
where c is the speed of light, R is the distance between the radar platform and the target, V is the radial velocity of the relative motion between the radar platform and the target, and f Doppler Doppler frequency shift caused by the relative motion radial velocity of the radar platform and the target;
the four outputs of the echo light beam and the local oscillator light beam after being mixed by the 2 × 4 90-degree optical bridge are respectively:
wherein phi is N-n Is the nth output beam mixing noise phase, I S Is a direct current quantity related to the echo beam; i is O Is the direct current quantity related to the local oscillator beam;
the in-phase signal and the orthogonal signal with the orthogonal characteristic output by the optical bridge connector are respectively received by a photoelectric balance detector to obtain an intermediate frequency signal containing target distance and speed information; in the intermediate frequency signal of the forward frequency modulation process, the in-phase signal and the quadrature signal are respectively as follows:
in the intermediate frequency signal of the negative direction frequency modulation process, the in-phase signal and the orthogonal signal are respectively as follows:
wherein k is in Is the response rate, k, of a photoelectric balanced detector receiving in-phase signals qu Is the response rate, phi, of a photoelectric balanced detector receiving quadrature signals i-n And phi q-n Noise phases of the in-phase signal and the quadrature signal, respectively;
the amplitudes of the in-phase and quadrature channels are replaced by:
the in-phase signal and the orthogonal signal in the intermediate frequency signal in the forward frequency modulation process are simplified as follows:
in-phase signals and orthogonal signals in intermediate frequency signals in the negative frequency modulation process are simplified as follows:
the in-phase signal and the orthogonal signal are respectively subjected to analog-to-digital conversion through an analog-to-digital converter, and then are acquired by a field programmable gate array to be subjected to parallel fast Fourier transform, wherein the Fourier transform of the in-phase signal is represented as follows:
the orthogonal signal fourier transform is represented as:
performing cross-spectrum processing on the two channels:
wherein denotes conjugation;
finally, only the imaginary part is taken to obtain:
Img＝δ 2 (f-f n )-δ 2 (f+f n )，
the frequency values in the positive frequency modulation process and the negative frequency modulation process can be respectively obtained by extracting the peak position and the positive and negative of the frequency spectrum through a gravity center method:
from the above formula one can obtain:
in the above formula, f n-up Is the value of the intermediate frequency in the forward frequency modulation process, f n-down Is the intermediate frequency value in the course of negative frequency modulation, f Doppler Doppler frequency shift caused by the relative motion radial velocity of the radar platform and the target;
because the Doppler frequency is in direct proportion to the relative movement speed of the radar platform and the target, the positive and negative Doppler frequency shifts are related to the direction of the relative movement radial speed, the positive frequency shift represents that the radar platform and the target move in the opposite direction, and the negative frequency shift represents that the radar platform and the target move in the opposite direction, the magnitude and the direction of the relative movement radial speed of the radar platform and the target can be obtained through the Doppler frequency shift, and therefore the magnitude and the direction of the relative movement radial speed of the radar platform and the target can be obtained through the Doppler frequency shift and are represented as
Where λ is the output beam wavelength, f Doppler Doppler frequency shift caused by the relative motion radial velocity of the radar platform and the target;
and obtaining the distance between the radar platform and the target point according to the formula:
5. The vehicle-mounted coherent lidar high-resolution 3D imaging method according to claim 2, wherein: the MEMS two-dimensional scanner realizes 3D point cloud images of targets in an axial push-broom state, specifically, the MEMS two-dimensional scanner adopts line-by-line scanning, light spots reflected by micro-reflectors in the MEMS two-dimensional scanner do sawtooth wave or triangular wave motion in the vertical direction and do simple harmonic motion in the horizontal direction to form a scanning light spot array, the scanning angle of the MEMS two-dimensional scanner in the vertical direction is theta, and the scanning angle range of the MEMS two-dimensional scanner in the vertical direction is theta
The vertical angular resolution is determined by the beam divergence angle delta theta in the vertical direction, and thus the number of scan lines in the vertical direction
When the distance between the plane of the radar platform and the target plane is L m Then, where the scan array of the initial frame image is denoted by subscript m, the period of the vertical direction scan lines is:
the distance between the plane of the radar platform and the target plane is L along with the advance of the radar platform m+k And obtaining a scanning array of the m + k frame image, wherein the period of the scanning line in the vertical direction is as follows:
6. the vehicle-mounted coherent lidar high-resolution 3D imaging method according to claim 5, wherein: taking the initial position of the radar platform as the origin of coordinates O m Through O m And a point O on the target plane m+1 Establishing Z m Axes, establishing a stationary coordinate system X in right-hand rule m Y m Z m O m (ii) a Taking O as the origin of coordinates of the target coordinate system, and passing through the origin of coordinates O by Z m Establishing a coordinate axis Z in the positive direction, and establishing a static coordinate system XYZO for the target position according to the right-hand rule; after 1 frame of scanning time delta T, the motion coordinate system where the radar platform is located takes the speed as V m Move to X m+1 Y m+1 Z m+1 O m+1 Wherein the origin of coordinates O m+1 Is the real-time position of the moving state of the radar platform,
coordinate system X at initial position of radar platform m Y m Z m O m By the obtained target P distance R m And radar platform velocity V m Azimuth angle epsilon of the radiation beam m Angle of pitch η of the emitted beam m Thus the coordinates (x) of the target P in the coordinate system P_m ,y P_m ,z P_m ) Expressed as:
in the radar platform position coordinate system X m+1 Y m+1 Z m+1 O m+1 By the obtained target P distance R m+1 And radar platform velocity V m+1 Azimuthal angle epsilon of the emitted beam m+1 Angle of pitch η of the emitted beam m+1 Thus the coordinates (x) of the target P in the coordinate system P_m+1 ,y P_m+1 ,z P_m+1 ) Expressed as:
since the time interval Δ T between the m-th frame and the m + 1-th frame is short, V m ΔT＜＜R m The following approximate relationship is obtained:
by analogy, the coordinate approximation relationship of the target P between the m + k-1 th frame and the m + k th frame is as follows:
finally, the coordinate approximation relation of the target P between the mth frame and the m + k frame can be obtained:
therefore, on one hand, the relative speed between the radar platform and the target is measured, the integral is calculated to obtain the position coordinate system of the radar platform and the coordinate of the target in the coordinate system at different moments, so that the distance compensation quantity of the point cloud image of the (m + 1) th frame and the (m + k) th frame … … relative to the initial frame image is obtained, and then distance compensation is carried out on each frame image, namely interframe compensation is carried out;
on the other hand, the relative speed V between the radar platform and the target is kept constant within the scanning duration delta tau of each frame, the number of scanning points of each frame is M, and the duration period of each scanning point is
No compensation at 1 st point and compensation at 2 nd point
3 rd point compensation
… … Mth point compensation
Namely, the intra-frame compensation of each frame of image is realized;
after compensation, combining each frame image with the initial frame image, and acquiring a space point set of target coordinates in a time period tau = (k + 1) Δ T from the m-th frame to the m + k-th frame:
the space point set sigma P is the finally displayed 3D point cloud image.
7. Apparatus for implementing the vehicle-mounted coherent lidar high resolution 3D imaging method of any of claims 1 to 6, wherein: the device comprises a linear frequency modulation continuous wave laser light source (1), wherein the output end of the linear frequency modulation continuous wave laser light source (1) is sequentially connected with a polarizer (2) and a 1 x 2 beam splitter (3), and the 1 x 2 beam splitter (3) is connected with an optical circulator (4);
the output end of the optical circulator (4) is sequentially connected with an MEMS two-dimensional scanner (5) and an optical telescope (6); the optical circulator (4) and the 1 multiplied by 2 beam splitter (3) are connected with an optical bridge (7); the output end of the optical bridge (7) is sequentially connected with a photoelectric balance detector (8), an analog-to-digital converter (11) and a field programmable gate array (9), and the output end of the field programmable gate array (9) is connected with a main control computer (10); the main control computer (10) is also connected with the MEMS two-dimensional scanner (5).
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101980049A (en) * | 2010-09-17 | 2011-02-23 | 中国科学院上海光学精密机械研究所 | Fresnel telescope imaging laser radar |
| CN104931966A (en) * | 2015-06-12 | 2015-09-23 | 北京航空航天大学 | DCS algorithm-based satellite-borne video SAR (synthetic aperture radar) imaging processing method |
| CN105572679A (en) * | 2016-02-04 | 2016-05-11 | 重庆大学 | Scanning data correction method and system of two-dimensional scanning type laser radar |
| CN110794421A (en) * | 2020-01-03 | 2020-02-14 | 杭州爱莱达科技有限公司 | Pseudo-random code time delay self-differential interference three-dimensional imaging laser radar method and device |
| CN110806586A (en) * | 2020-01-08 | 2020-02-18 | 杭州爱莱达科技有限公司 | Non-scanning linear frequency modulation continuous wave speed and distance measuring laser three-dimensional imaging method and device |
| CN110988907A (en) * | 2019-11-25 | 2020-04-10 | 中国科学院上海光学精密机械研究所 | Doppler compensation based three-dimensional coherent laser radar push-scanning imaging method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8948497B2 (en) * | 2012-09-04 | 2015-02-03 | Digital Signal Corporation | System and method for increasing resolution of images obtained from a three-dimensional measurement system |
| KR20170096723A (en) * | 2016-02-17 | 2017-08-25 | 한국전자통신연구원 | Lidar system and multiple detection signal processing method thereof |
-
2020
- 2020-06-01 CN CN202010485924.0A patent/CN111650601B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101980049A (en) * | 2010-09-17 | 2011-02-23 | 中国科学院上海光学精密机械研究所 | Fresnel telescope imaging laser radar |
| CN104931966A (en) * | 2015-06-12 | 2015-09-23 | 北京航空航天大学 | DCS algorithm-based satellite-borne video SAR (synthetic aperture radar) imaging processing method |
| CN105572679A (en) * | 2016-02-04 | 2016-05-11 | 重庆大学 | Scanning data correction method and system of two-dimensional scanning type laser radar |
| CN110988907A (en) * | 2019-11-25 | 2020-04-10 | 中国科学院上海光学精密机械研究所 | Doppler compensation based three-dimensional coherent laser radar push-scanning imaging method |
| CN110794421A (en) * | 2020-01-03 | 2020-02-14 | 杭州爱莱达科技有限公司 | Pseudo-random code time delay self-differential interference three-dimensional imaging laser radar method and device |
| CN110806586A (en) * | 2020-01-08 | 2020-02-18 | 杭州爱莱达科技有限公司 | Non-scanning linear frequency modulation continuous wave speed and distance measuring laser three-dimensional imaging method and device |
Non-Patent Citations (6)
| Title |
|---|
| "Deep-learning-based 2.5D flow field estimation for maximum intensity projections of 4D optical coherence tomography";Max-Heinrich Laves et al.;《Proc. SPIE 10951, Medical Imaging 2019: Image-Guided Procedures, Robotic Interventions, and Modeling》;20190308;1-4 * |
| "Fast 3D in vivo swept-source optical coherence tomography using a two-axis MEMS scanning micromirror";Karthik Kumar et al.;《Journal of Optics A: Pure and Applied Optics》;20080403;第10卷(第4期);1-3 * |
| "Lensless optical image processing based on two-dimensional Fresnel diffraction for synthetic-aperture imaging ladar";Zhiwei Sun et al.;《Applied Optics》;20151231;第54卷(第4期);627-635 * |
| "Simulations of Optical Autofocus Algorithms Based on PGA in SAIL: Web of Science";Nan Xu et al.;《Proc. SPIE 8135, Applications of Digital Image Processing XXXIV》;20110924;1-10 * |
| "合成孔径激光成像雷达的二维匹配滤波成像算法";孙志伟 等;《光学学报》;20141231;第34卷(第12期);1-5 * |
| "大视场合成孔径激光雷达光学系统研究";李一哲 等;《中国优秀硕士学位论文全文数据库》;20190615;19-36 * |
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