Road surface preview system and method based on all-solid-state single-line FMCW laser radar
Through all-solid-state single-line FMCW lidar technology, the problem of reducing measurement accuracy of the binocular visual road surface pre-aim system under light changes, monotonous scenes and vehicle vibration is solved, and the road surface pre-aim effect with high accuracy and strong adaptability is achieved.
Patent Information
- Application Number
- CN202510154083.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-12
- Publication Date
- 2025-04-15
AI Technical Summary
The existing binocular visual pavement pre-aim system has reduced measurement accuracy under light changes, monotonous and lack of texture and vehicle vibration, with high computational complexity and limited measurement range.
The all-solid-state single-line FMCW lidar is adopted to realize all-solid-state single-line scanning through optical switch switching, integrate optical devices onto the optical chip, and combine vehicle movement and multiple measurement results to achieve the measurement effect of the multi-line lidar.
Improves measurement range and accuracy, reduces the amount of calculation, and is almost immune to light, monotonous and lack of texture scenes and vehicle vibrations, adapting to more scenes.
Smart Images
Figure CN119828108A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of road surface undulation detection, and in particular to a road surface preview system and method based on a fully solid-state single-line FMCW laser radar. Background Art
[0002] The stiffness and damping characteristics of the active suspension system of the car can be dynamically and adaptively adjusted according to the driving conditions of the car (the vehicle's motion state and road conditions, etc.), so that the suspension system is always in the best vibration reduction state. Active suspension has many advantages, such as controlling the height of the vehicle body, improving the passability, taking into account the smoothness and handling stability of the car, reducing wheel load fluctuations, improving adhesion performance, improving handling, and reducing tire wear.
[0003] Road preview is a technology that automatically detects road undulations. It can provide the active suspension system with road undulation data ahead. Based on this data, the active suspension system can make judgments in advance and make corresponding adjustments more timely and accurately, which can further improve the performance of the active suspension system, reduce vehicle bumps, and improve driving comfort. Especially for some rescue vehicles, reducing bumps during high-speed driving is of great help to rescue.
[0004] At present, road preview uses binocular vision distance sensors to detect the undulation of the road surface. Binocular vision sensors are very sensitive to ambient light. In strong light (overexposure) and dark light conditions, the algorithm effect will drop sharply. The computational complexity of binocular vision is high. It needs to calculate the matching pixel by pixel. It needs to ensure that the matching result is relatively robust. A large number of error rejection strategies will be added to the algorithm. Therefore, the algorithm has high requirements. It is difficult to achieve reliable commercial use and the amount of calculation is large. Binocular vision is also not suitable for monotonous scenes lacking texture. For scenes lacking visual features (such as clean roads, rainy and snowy roads, etc.), matching will be difficult, resulting in large matching errors or even matching failures. The measurement range of binocular vision is closely related to the baseline (the distance between the two cameras): the larger the baseline, the longer the measurement range; the smaller the baseline, the closer the measurement range. The baseline cannot be made very long in the vehicle-mounted scene, which limits its measurement range to a certain extent. The accuracy of the binocular vision measurement result is closely related to the position and angle of the two cameras. In the vehicle-mounted environment, the relative position and angle of the two cameras will change due to vehicle vibration, and the measurement result accuracy is slightly lower. Summary of the invention
[0005] The purpose of the present application is to overcome the problems of the binocular vision road preview system in the prior art, that is, the preview effect is easily affected by light, monotonous scenes lacking texture, and vehicle vibration, resulting in reduced measurement accuracy, as well as high calculation complexity and limited measurement range, and to provide a road preview system and method based on a fully solid-state single-line FMCW laser radar.
[0006] In a first aspect, a road surface preview system based on a fully solid-state single-line FMCW laser radar is provided, comprising a laser, wherein the output end of the laser is connected to a beam splitter, wherein the laser signal input to the beam splitter is an FMCW signal, the first output end of the beam splitter is connected to a polarization beam splitter rotator, the second output end of the beam splitter is connected to a mixer, the first output end of the polarization beam splitter rotator is connected to an optical switch array, the optical switch array is connected to an optical switch array driver, the output end of the optical switch array is connected to an antenna array, the output end of the antenna array is provided with a collimating lens, the second output end of the polarization beam splitter rotator is connected to the mixer, the output end of the mixer is connected to a photodetector, the output end of the photodetector is connected to an amplifier, the output end of the amplifier is connected to an analog-to-digital converter, the output end of the analog-to-digital converter is connected to a signal processor, the signal processor and the optical switch array driver are both electrically connected to a central processing unit, and the central processing unit is electrically connected to an inertial sensor.
[0007] In some possible implementations, the input end of the laser is connected to a laser driver, and the laser driver generates a triangular frequency modulated continuous wave through cathode modulation control to drive the laser to emit an FMCW signal, and the laser driver is electrically connected to a central processing unit.
[0008] In some possible implementations, the input end of the laser is connected to a laser driver, the output end of the laser is connected to a FMCW modulator, the output end of the FMCW modulator is connected to a beam splitter, and the laser driver is electrically connected to a central processing unit.
[0009] In some possible implementations, the inertial sensor includes a gyroscope.
[0010] In some possible implementations, the optical switch array includes multiple optical switches, wherein the optical switches at the last stage are all connected to antennas, and the optical switches include a multimode interference coupler 1×2, wherein the first output end and the second output end of the multimode interference coupler 1×2 are both connected to phase shifters, and the output ends of the phase shifters are both connected to the multimode interference coupler 2×2.
[0011] In some possible implementations, the central processing unit is electrically connected to an IO interface.
[0012] In a second aspect, a road surface preview method based on a fully solid-state single-line FMCW laser radar is provided, including a system as described in any one of the implementations of the first aspect above, the method comprising:
[0013] S100, driving the optical switch array to generate an instruction to switch the laser to a designated antenna for transmission;
[0014] S200, acquiring detection signals by synchronizing an analog-to-digital converter according to a laser driving signal, calculating detection distance and vehicle speed using a signal processor, obtaining a beam scanning angle according to a position of an antenna emitting laser, and obtaining an angle between the laser and the ground according to inertial sensor data;
[0015] S300, calculating the height of the current measurement point according to the beam scanning angle, the angle between the laser and the ground, the detection distance and the installation height of the laser;
[0016] S400, switching the antennas emitting lasers in sequence according to a preset order so that the lasers are swung left and right to scan, and steps S100-S300 are repeated;
[0017] S500: Integrate the height information of the measurement points during the movement of the vehicle into road surface change information.
[0018] In some possible implementations, the calculation formula for the height of the current measurement point is:
[0019] h=Hr*cos(α) / sin(θ)
[0020] Here, h is the height of the current measurement point, r is the detection distance, α is the beam scanning angle, θ is the angle between the laser and the ground, and H is the installation height of the laser.
[0021] In some possible implementations, the method further includes: sending the road surface change information to the vehicle, so that the vehicle dynamically adjusts the stiffness and damping characteristics of the active suspension according to the road surface change information.
[0022] In a third aspect, a computer-readable storage medium is provided, wherein the computer-readable medium stores a program code for execution by a device, wherein the program code includes steps for executing the method in any one of the implementations of the first aspect described above.
[0023] The present application has the following beneficial effects: the present application only requires a single-line laser to realize all-solid-state single-line scanning by means of optical switch switching, and can integrate optical devices such as optical switches, beam splitters and polarization rotators onto an optical chip. It not only has high integration, small size and low cost, but also utilizes the movement of the vehicle itself and combines multiple single-line laser radar measurement results to achieve the measurement effect of a multi-line laser radar. The measurement range and measurement accuracy are relatively high. Compared with binocular vision, the amount of calculation required for this application is greatly reduced, and it is almost unaffected by light, monotonous scenes lacking texture, and vehicle vibration, and can adapt to more scenarios. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application.
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0026] Figure 1 It is a structural block diagram of a road surface preview system based on a fully solid-state single-line FMCW laser radar according to Example 1 of the present application;
[0027] Figure 2 It is a schematic diagram of adjusting the laser signal through external modulation in the road preview system based on the all-solid-state single-line FMCW laser radar of Example 1 of the present application;
[0028] Figure 3 It is a schematic diagram of an optical switch array and an antenna array in a road surface preview system based on a fully solid-state single-line FMCW laser radar according to Example 1 of the present application;
[0029] Figure 4 is a schematic diagram of an optical switch in a road surface preview system based on a fully solid-state single-line FMCW laser radar according to Example 1 of the present application;
[0030] Figure 5 is a flow chart of a road surface preview method based on a fully solid-state single-line FMCW laser radar according to Example 2 of the present application;
[0031] Figure 6 It is a schematic diagram of calculating the road surface height in the road surface preview method based on the all-solid-state single-line FMCW laser radar in Example 2 of the present application.
[0032] Reference numerals:
[0033] 100. Laser; 101. Beam splitter; 102. Polarization beam splitter rotator; 103. Mixer; 104. Photodetector; 105. Amplifier; 106. Analog-to-digital converter; 107. Signal processor; 108. Laser driver; 109. FMCW modulator; 200. Optical switch array; 201. Optical switch array driver; 202. Optical switch; 2021. Multimode interference coupler 1×2; 2022. Phase shifter; 2023. Multimode interference coupler 2×2; 300. Antenna array; 301. Antenna; 400. Collimating lens; 500. Central processing unit; 600. Inertial sensor; 700. IO interface; 800. Vehicle; 900. Edge coupler. DETAILED DESCRIPTION
[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0035] Example 1
[0036] like Figure 1 As shown, a road surface preview system based on a fully solid-state single-line FMCW laser radar according to Example 1 of the present application includes a laser 100, which is controlled by a laser driver 108. The light output by the laser 100 is divided into two beams through a beam splitter 101, one beam directly enters the mixer 103 as a local oscillator light, and the other beam enters the optical switch array 200 after passing through a polarization beam splitter rotator 102. The optical switch array 200 can switch the light to any antenna 301 in the antenna array 300, and then pass through a collimating lens 400 to convert the laser into a collimated light beam and emit it to the target. After the light reflected by the target is received by the collimating lens 400, The signal is returned to the polarization beam splitter rotator 102 (PRS) via the same antenna 301. The polarization beam splitter rotator 102 will separate the light with different polarization states from the laser 100 and perform polarization rotation. Since the polarization state of the light reflected by the target object will change, the signal light reflected by the target object will be separated and polarization rotated before entering the mixer 103, where it is mixed with the local oscillator light. The mixed signal is converted into an electrical signal by the photodetector 104, amplified by the amplifier 105, and collected by the analog-to-digital converter 106 (ADC) to obtain a digital signal. Finally, the signal processor 107 processes and calculates the digital signal to obtain the distance of the target object. Among them, the optical switch array driver 201 is used to control the optical switch array 200, so that the light is switched to different antennas 301 in the antenna array 300. The antennas 301 at different positions have different emission angles of light beams after passing through the collimating lens 400, so that targets in different directions can be detected. The central processing unit 500 coordinates and controls other parts. The central processing unit 500 is electrically connected to the IO interface 700 and communicates with the outside through the IO interface 700. Only one single-line laser 100 is required to realize full solid-state single-line scanning by switching with an optical switch 202, and optical devices such as the optical switch 202, the beam splitter 101 and the polarization rotator can be integrated into the optical chip, which has high integration, small size and low cost.
[0037] In a possible embodiment, Figure 1As shown, the input end of the laser 100 is connected to a laser driver 108 , and the laser driver 108 generates a triangular frequency modulated continuous wave through cathode modulation control to drive the laser 100 to emit an FMCW signal. The laser driver 108 is electrically connected to the central processor 500 .
[0038] In another possible embodiment, Figure 2 As shown, the input end of the laser 100 is connected to a laser driver 108 , the output end of the laser 100 is connected to a FMCW modulator 109 , the output end of the FMCW modulator 109 is connected to the beam splitter 101 , and the laser driver 108 is electrically connected to the central processor 500 .
[0039] like Figure 3 As shown, the optical part of the all-solid-state single-line scanning FMCW laser radar of this embodiment can be integrated into an optical chip. The laser 100 couples the light from the side coupler 900 to the optical chip through an optical fiber or a lens. A directional coupler is used as a beam splitter 101 to split the light into two beams, one of which enters a polarization beam splitter rotator 102 (PRS) and the other enters a mixer 103 implemented by a multi-mode interference coupler (MMI). The light after passing through the polarization beam splitter rotator 102 enters an optical switch array 200 composed of cascaded 1×2 optical switches 202. The optical switch array 200 can switch the light to 2-N antennas 301. According to the actual resolution and field of view requirements, the number of levels N of the optical switches 202 can be flexibly selected. For example, a 7-level 1×2 optical switch 202 can be used to switch the light to 128 antennas 301, and the total number of points for single-line scanning is 128 points. The received optical signal is also returned to the PRS (i.e., the polarization beam splitter rotator 102) through the antenna 301 and the optical switch array 200, and is separated and enters the MMI, and after mixing with the local oscillator light, enters the balanced photodetector 104 (BPD) to be converted into an electrical signal. Metal contacts connected to the outside are reasonably set on the optical chip according to the actual positions of various components related to the electrical signal, and these metal contacts can be connected to other circuits through wire bonding. The collimating lens 400 is fixed near the chip transmitting antenna array 300, and the distance between the lens and the chip transmitting edge is equal to the focal length of the lens. By utilizing the movement of the vehicle 800 itself and combining multiple single-line laser radar measurement results, the measurement effect of the multi-line laser radar is achieved, and the measurement range and measurement accuracy are relatively high. Compared with binocular vision, the amount of calculation required for this application is greatly reduced, and it is almost unaffected by light, monotonous scenes lacking texture, and vibrations of the vehicle 800, and can adapt to more scenes.
[0040] like Figure 4As shown, the optical switch 202 is composed of a multimode interference coupler 1×2 2021 (MMI), two phase shifters 2022, a multimode interference coupler 2×2 2023 (MMI) and a waveguide connecting the devices. Light enters from the entrance of MMI1×2 and is equally divided into two beams, which respectively pass through the phase shifter 2022 and enter the two ports of MMI2×2. The phase of the two beams of light can be controlled by the phase shifter 2022 so that the light can be output from any of the other two ports of MMI2×2. The phase shifter 2022 can be a thermo-optical phase shifter 2022 or a carrier dispersion phase shifter 2022.
[0041] In this embodiment, if Figure 1 As shown, the laser driver 108 can use a conventional cathode modulation control method to generate a conventional triangular wave frequency modulated continuous wave. The central processor 500 can be a micro control unit (MCU) and the corresponding model can be selected according to actual needs. The amplifier 105 can use a transimpedance amplifier plus a first-stage amplifier to form a secondary amplifier 105, and the analog-to-digital converter 106 (ADC) selects a suitable sampling rate and sampling accuracy according to the frequency and size of the signal. The signal processor 107 can be a programmable logic gate array (FPGA). The optical switch array driver 201 can be composed of a multi-channel digital-to-analog converter (DAC) plus a multi-channel operational amplifier 105. The number of channels is determined according to the number of optical switches 202 in the optical switch array 200. The DAC and the operational amplifier 105 determine the appropriate voltage output parameters according to the half-wave voltage of the optical switch 202. The inertial sensor 600 can be a gyroscope, and the IO interface 700 can be a serial port or a parallel port.
[0042] Example 2
[0043] like Figure 5 As shown, a road surface preview method based on a fully solid-state single-line FMCW laser radar according to Embodiment 2 of the present application includes:
[0044] S100, the central processor 500 issues an instruction to the optical switch array driver 201 to switch the laser to the designated antenna 301 for transmission;
[0045] S200, according to the laser drive 108 signal, the analog-to-digital converter 106 is synchronized to collect the detection signal, the detection distance and the speed of the vehicle 800 are calculated by the signal processor 107, the beam scanning angle is obtained according to the position of the antenna 301 emitting the laser, and the angle between the laser and the ground is obtained according to the inertial sensor 600 data;
[0046] S300, such as Figure 6 As shown, the height h of the current measuring point is calculated according to the beam scanning angle α, the angle θ between the laser and the ground, the detection distance r and the installation height H of the laser 100, and the calculation formula is:
[0047] h=Hr*cos(α) / sin(θ)
[0048] Here, h is the height of the current measurement point, r is the detection distance, α is the beam scanning angle, θ is the angle between the laser and the ground, and H is the installation height of the laser 100;
[0049] S400, switching the laser emitting antenna 301 in sequence according to a preset order so that the laser swings left and right to scan, and repeating steps S100-S300 to perform the next measurement. By high-frequency left and right swing scanning, horizontal scanning can be achieved, and the height of the next position can be obtained after the vehicle 800 moves. In this way, the road height information of the area in front of the vehicle 800 can be obtained by repeating the cycle;
[0050] S500, integrating the height information of the measurement points during the movement of the vehicle 800 into road surface change information, sending the road surface height change information to the vehicle 800, and related components on the vehicle 800 act in advance according to the road surface height information to reduce bumps during driving.
[0051] Compared with the road surface preview method based on binocular vision, the road surface preview system of the present application has high integration and low cost, relatively high measurement range and measurement accuracy, greatly reduced required calculation amount, and the laser is almost unaffected by light, monotonous scenes lacking texture, and vehicle 800 vibration, and can adapt to more scenarios.
[0052] It should be noted that other specific implementation methods of the road surface preview method based on the all-solid-state single-line FMCW laser radar in this embodiment can refer to the specific implementation methods of the road surface preview system based on the all-solid-state single-line FMCW laser radar mentioned above. In order to avoid redundancy, they will not be repeated here.
[0053] Example 3
[0054] A computer-readable storage medium according to Embodiment 3 of the present application, wherein the computer-readable storage medium stores a program code for execution by a device, wherein the program code includes steps for executing a method in any one of the implementations in Embodiment 1 of the present application;
[0055] Among them, the computer-readable storage medium can be a read-only memory (ROM), a static storage device, a dynamic storage device or a random access memory (RAM); the computer-readable storage medium can store program code, and when the program stored in the computer-readable storage medium is executed by the processor, the processor is used to execute the steps of the method in any one of the implementation methods in Example 1 of the present application.
[0056] The above are only preferred specific implementations of the present application; however, the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved ideas of the present application within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.
Claims
1. A road preview system based on a fully solid-state single-line FMCW laser radar, characterized in that: The invention comprises a laser, wherein the output end of the laser is connected to a beam splitter, wherein the laser signal input to the beam splitter is an FMCW signal, the first output end of the beam splitter is connected to a polarization beam splitter rotator, the second output end of the beam splitter is connected to a mixer, the first output end of the polarization beam splitter rotator is connected to an optical switch array, the optical switch array is connected to an optical switch array driver, the output end of the optical switch array is connected to an antenna array, the output end of the antenna array is provided with a collimating lens, the second output end of the polarization beam splitter rotator is connected to the mixer, the output end of the mixer is connected to a photodetector, the output end of the photodetector is connected to an amplifier, the output end of the amplifier is connected to an analog-to-digital converter, the output end of the analog-to-digital converter is connected to a signal processor, the signal processor and the optical switch array driver are both electrically connected to a central processing unit, and the central processing unit is electrically connected to an inertial sensor.
2. The road preview system based on the all-solid-state single-line FMCW laser radar according to claim 1 is characterized in that: The input end of the laser is connected to a laser driver, and the laser driver generates a triangular frequency modulated continuous wave through a cathode modulation control method to drive the laser to emit an FMCW signal. The laser driver is electrically connected to a central processing unit.
3. The road surface preview system based on the all-solid-state single-line FMCW laser radar according to claim 1 is characterized in that: The input end of the laser is connected to a laser driver, the output end of the laser is connected to a FMCW modulator, the output end of the FMCW modulator is connected to a beam splitter, and the laser driver is electrically connected to a central processing unit.
4. The road surface preview system based on the all-solid-state single-line FMCW laser radar according to claim 1 is characterized in that: The inertial sensor is a gyroscope.
5. The road surface preview system based on the all-solid-state single-line FMCW laser radar according to claim 1 is characterized in that: The optical switch array includes multiple optical switches, wherein the optical switches at the last stage are all connected to antennas, and the optical switches include a multimode interference coupler 1×2, wherein the first output end and the second output end of the multimode interference coupler 1×2 are both connected to phase shifters, and the output ends of the phase shifters are both connected to the multimode interference coupler 2×2.
6. The road surface preview system based on all-solid-state single-line FMCW laser radar according to claim 1 is characterized in that: The central processing unit is electrically connected to an IO interface.
7. A road surface preview method based on all-solid-state single-line FMCW laser radar, characterized in that: The method comprises: S100, driving the optical switch array to generate an instruction to switch the laser to a designated antenna for transmission; S200, acquiring detection signals by synchronizing an analog-to-digital converter according to a laser driving signal, calculating detection distance and vehicle speed using a signal processor, obtaining a beam scanning angle according to a position of an antenna emitting laser, and obtaining an angle between the laser and the ground according to inertial sensor data; S300, calculating the height of the current measurement point according to the beam scanning angle, the angle between the laser and the ground, the detection distance and the installation height of the laser; S400, switching the antennas emitting lasers in sequence according to a preset order so that the lasers are swung left and right to scan, and steps S100-S300 are repeated; S500: Integrate the height information of the measurement points during the movement of the vehicle into road surface change information.
8. The road surface preview method based on all-solid-state single-line FMCW laser radar according to claim 7 is characterized in that: The calculation formula for the height of the current measuring point is: h=Hr*cos(α) / sin(θ) Here, h is the height of the current measurement point, r is the detection distance, α is the beam scanning angle, θ is the angle between the laser and the ground, and H is the installation height of the laser.
9. The road surface preview method based on all-solid-state single-line FMCW laser radar according to claim 7 is characterized in that: Also includes: The road surface change information is sent to the vehicle, so that the vehicle dynamically adjusts the stiffness and damping characteristics of the active suspension according to the road surface change information.
10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program code for execution by a device, wherein the program code includes steps for executing the method according to any one of claims 7 to 9.