Vehicle-mounted lidar based on dynamic adjustment of optical frequency, and control method therefor

Abstract

A vehicle-mounted LiDAR based on dynamic adjustment of an optical frequency, and a control method therefor. The LiDAR comprises a laser light source, a light path regulator, a temperature regulator, an emission angle control module, an external light-guiding medium and a LiDAR controller. The laser light source is connected to the light path regulator by means of an optical fiber; the light path regulator is connected to the emission angle control module by means of an optical fiber; the external light-guiding medium is arranged at a light emission position of the emission angle control module; the temperature regulator is arranged on the outer side of the light path regulator; the light path regulator, the emission angle control module and the temperature regulator are all electrically connected to the LiDAR controller; and the LiDAR controller is electrically connected to a vehicle CAN bus.

Description

A vehicle-mounted laser radar based on dynamic adjustment of optical frequency and its control method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] [Corrected on 12.07.2024 according to Rule 91] The embodiments of this application are based on the Chinese patent application with application number 202311207690.3 and application date September 18, 2023, and claim the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into the embodiments of this application as a reference. Technical Field

[0003] The present invention relates to the field of vehicle perception and detection technology, and in particular to a vehicle-mounted laser radar based on dynamic adjustment of optical frequency and a control method thereof. Background Art

[0004] Currently, related lidar systems mostly use laser ranging methods during product design and development. A rotating laser structure or laser reflection structure inside the lidar deflects the laser to various directions in a very short time. The distance measurement in various directions is completed by intensively receiving the returned laser, and finally a laser point cloud is formed to form the spatial structure around the lidar.

[0005] However, these methods have significant drawbacks. To achieve the development goals of a LiDAR system, they require a high-speed rotating laser structure or laser reflector. Furthermore, the laser generating or reflecting structure must be absolutely stable, unable to tolerate even the slightest displacement or relative position change caused by vehicle vibrations. Consequently, the current cost of LiDAR is extremely high.

[0006] Due to the propagation characteristics of light, non-dynamic lidar has problems such as a narrow detection range. Multiple lidars need to be installed on the vehicle, and the cost cannot be effectively reduced.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a vehicle-mounted laser radar based on dynamic adjustment of optical frequency to achieve laser radar scanning without a mechanical rotating structure.

[0009] To solve the above technical problems, the present invention provides a technical solution: a vehicle-mounted laser radar based on dynamic adjustment of optical frequency. The laser radar includes a laser light source, an optical path regulator, a temperature regulator, an emission angle control module, an external light guiding medium, and a laser radar controller;

[0010] The laser light source is connected to the optical path regulator via an optical fiber, the optical path regulator is connected to the output angle control module via an optical fiber, and the external light guide medium is arranged at the light output position of the output angle control module; a temperature regulator is arranged on the outside of the optical path regulator, the optical path regulator, the output angle control module, and the temperature regulator are all electrically connected to the laser radar controller, and the laser radar controller is electrically connected to the vehicle CAN bus;

[0011] After the laser light source emits the laser, it is transmitted through the optical fiber and the optical path regulator, and is emitted from the emission angle control module. After emission, it is refracted by the external light-guiding medium and becomes the detection light; during the laser radar detection process, the emission angle control module adjusts the emission position of the laser according to the instructions of the laser radar controller, the laser light source adjusts the light intensity of the laser according to the instructions of the laser radar controller, the optical path regulator adjusts the propagation length of the laser in the light-guiding medium in the optical path regulator according to the instructions of the laser radar controller, and the temperature regulator adjusts the temperature of the light-guiding medium in the optical path regulator according to the instructions of the laser radar controller.

[0012] Based on the same inventive concept, the present invention also provides a vehicle-mounted laser radar detection method implemented by the vehicle-mounted laser radar based on dynamic adjustment of optical frequency as described above, comprising the following steps:

[0013] The LiDAR starts working when it receives a call request signal from the vehicle's CAN bus;

[0014] The laser emission angle is roughly adjusted by adjusting the laser emission position of the emission angle control module;

[0015] The laser light source is used to adjust the laser light intensity, the optical path regulator is used to adjust the laser propagation length in the light-guiding medium in the optical path regulator, and the temperature regulator is used to adjust the temperature of the light-guiding medium in the optical path regulator. By combining the effects of changes in the laser light intensity, the propagation length in the light-guiding medium in the optical path regulator, and the temperature of the light-guiding medium in the optical path regulator, the optical frequency of the laser when incident on the external light-guiding medium is changed, thereby achieving precise adjustment of the light emission angle.

[0016] The above coarse adjustment and fine adjustment are performed cyclically until the laser radar completes continuous scanning within a certain range, and then the generated laser radar point cloud is obtained;

[0017] Output detection results based on the lidar point cloud.

[0018] Based on the same inventive concept, the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the computer program, the steps of the vehicle-mounted lidar detection method described above are implemented.

[0019] Based on the same inventive concept, the present invention also provides a car, which is equipped with the above-mentioned on-board laser radar based on dynamic adjustment of optical frequency.

[0020] The beneficial effects of the present invention are as follows: the laser emission position is adjusted through the emission angle control module to achieve coarse adjustment of the laser emission angle; the laser propagation path in the optical path regulator is adjusted to change the laser propagation length and the number of phase cycles passed during the propagation process; the temperature of the light-guiding medium in the optical path regulator is adjusted through the temperature regulator to change its refractive index; and the changes in the laser propagation length, the number of phase cycles passed during the laser propagation process, and the refractive index of the light-guiding medium are comprehensively considered to ultimately change the optical frequency of the laser when it is incident on the external light-guiding medium, thereby achieving fine adjustment of the light emission angle. This laser radar replaces the mechanical rotation scanning method of traditional laser radars by combining the above coarse and fine adjustment methods, and has lower hardware costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic diagram of the structure of a vehicle-mounted laser radar based on dynamic adjustment of optical frequency according to a first embodiment of the present invention;

[0022] FIG2 is a schematic structural diagram of an optical path regulator and a temperature regulator according to a first embodiment of the present invention;

[0023] FIG3 is a schematic diagram of a detection process of a vehicle-mounted laser radar according to a second embodiment of the present invention;

[0024] FIG4 is a schematic diagram of a process of fine adjustment according to a second embodiment of the present invention;

[0025] FIG5 is a schematic diagram of a light intensity curve at a light source according to a second embodiment of the present invention;

[0026] 6 is a fitted sine curve diagram of a certain section of the light intensity curve at the light source of the second embodiment of the present invention;

[0027] FIG7 is a schematic diagram of a light intensity curve at the light source and a light intensity curve at the exit in the second embodiment of the present invention. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0029] Example 1:

[0030] Referring to Figures 1 and 2, a vehicle-mounted laser radar based on dynamic adjustment of optical frequency includes a laser light source, an optical path regulator, a temperature regulator, an emission angle control module, an external light guiding medium, and a laser radar controller;

[0031] The laser light source is connected to the optical path regulator via an optical fiber, the optical path regulator is connected to the output angle control module via an optical fiber, and the external light guide medium is arranged at the light output position of the output angle control module; a temperature regulator is arranged on the outside of the optical path regulator, the optical path regulator, the output angle control module, and the temperature regulator are all electrically connected to the laser radar controller, and the laser radar controller is electrically connected to the vehicle CAN bus;

[0032] After the laser light source emits the laser, it is transmitted through the optical fiber and the optical path regulator, and is emitted from the emission angle control module. After emission, it is refracted by the external light-guiding medium and becomes the detection light; during the laser radar detection process, the emission angle control module adjusts the emission position of the laser according to the instructions of the laser radar controller, the laser light source adjusts the light intensity of the laser according to the instructions of the laser radar controller, the optical path regulator adjusts the propagation length of the laser in the light-guiding medium in the optical path regulator according to the instructions of the laser radar controller, and the temperature regulator adjusts the temperature of the light-guiding medium in the optical path regulator according to the instructions of the laser radar controller.

[0033] Furthermore, the optical path regulator is provided with a plurality of optical path regulating light gates; the optical path regulator controls the propagation path of the laser in the optical path regulator by controlling the opening and closing of different optical path regulating light gates.

[0034] Furthermore, the emission angle control module is provided with a plurality of emission light gates; the emission angle control module controls the emission position of the laser by controlling the opening and closing of different emission light gates; and the emission light gates are evenly distributed in a fan shape at certain angle intervals.

[0035] Example 2:

[0036] The basic principles underlying this embodiment are as follows:

[0037] Therefore, the frequency of the incident light wave can be adjusted to change the output angle.

[0038] The conditional range of its exit angle is

[0039] Based on the above principles, this embodiment proposes a vehicle-mounted laser radar detection method, referring to Figures 3 and 4, which includes the following steps:

[0040] The LiDAR starts working when it receives a call request signal from the vehicle's CAN bus;

[0041] The laser emission angle is roughly adjusted by adjusting the laser emission position of the emission angle control module;

[0042] The laser light source is used to adjust the laser light intensity, the optical path regulator is used to adjust the laser propagation length in the light-guiding medium in the optical path regulator, and the temperature regulator is used to adjust the temperature of the light-guiding medium in the optical path regulator. By combining the effects of changes in the laser light intensity, the propagation length in the light-guiding medium in the optical path regulator, and the temperature of the light-guiding medium in the optical path regulator, the optical frequency of the laser when incident on the external light-guiding medium is changed, thereby achieving precise adjustment of the light emission angle.

[0043] The above coarse adjustment and fine adjustment are performed cyclically until the laser radar completes continuous scanning within a certain range, and then the generated laser radar point cloud is obtained;

[0044] Output detection results based on the lidar point cloud.

[0045] Furthermore, the laser light source adjusts the laser intensity in the following manner:

[0046] Assume that the emission intensity of the laser light source is I B (t), I B (t) varies with time t, and the average light intensity of the laser incident on the optical fiber obtained by experimental measurement is I0; and further, it is set:

[0047] In the above formula, K 12 , K 34 is the optical conduction power coupling coefficient (K) corresponding to different optical paths in the optical path regulator 12 Indicates that the laser transmission path is from the optical path adjustment gate No. 1 to the optical path adjustment gate No. 2, K 34 = represents the laser transmission path from the optical path adjustment gate 3 to the optical path adjustment gate 4. In this embodiment, the laser light source emission intensity is adjusted based on only these two paths as the adjustment method. In practice, the laser light source emission intensity can be adjusted based on more paths. α is the power loss per unit length of the light guide medium, and s is the number of reflections during the laser propagation process. is the initial phase of the laser, c is the propagation speed of light in vacuum, n is the refractive index of the light-guiding medium, l is the laser propagation length, f is the light frequency, and m is the modulation coefficient;

[0048] There is K 12 =K 21 , K 43 =K 34 ;

[0049] Where T is the transfer function operator, and the subsequent calculation of T r , T0, Ta When , this operator can be used to replace the optimized calculation logic and simplify the calculation.

[0050] Furthermore, based on the set laser light source emission intensity I B (t), and the transfer function T of the laser inside the optical fiber is obtained r as follows:

[0051] In the above formula, I B is the instantaneous emission intensity of the laser light source, θ is the phase of the laser, where R, T0, T a satisfy:

[0052] Let m = 1, then:

[0053] Referring to Figures 5 to 7, according to the above formula, if the output light intensity of the fiber ring is set to the extreme value, the output light phase should satisfy θ = 2Nπ, where N is a natural number. Therefore, by adjusting K in the design of the laser radar 12 , K 34 The values ​​of θ and R are such that the output light phase of the laser when emitted from any optical path satisfies θ = 2Nπ (i.e., the corresponding light intensity maximum). The purpose of this setting is: 1) to count N; 2) to maintain the maximum value of the emitted laser light intensity, simplifying subsequent calculations; the laser frequency satisfies:

[0054] Furthermore, the method for adjusting the total propagation length of the laser light through the optical path modulator is as follows (if the temperature effect is ignored, the optical frequency change is only related to the propagation length of the light in the medium and the refractive index of the medium; since Δl generated by adjusting the propagation path of the laser light in the optical path modulator not only directly affects the optical frequency f, but also indirectly affects the optical frequency f by affecting the refractive index n);

[0055] Since the frequency change of light is expressed as:

[0056] In the above formula, Δn is the change of n, and Δl is the change of l;

[0057] When the influence of temperature and other uniform pressure fields is ignored, the following is satisfied:

[0058] Δl=l·ε z

[0059] In the above formula, ε z is the laser propagation length variation coefficient;

[0060] Since the propagation path of the laser in the optical path regulator is three-dimensional, and light is a single-phase wave, the refractive index of light in different dimensions is different, so the refractive index needs to be corrected for a specific propagation path;

[0061] The corresponding relationship between the refractive index change Δn and the internal optical path setting mode of the optical path regulator is expressed as:

[0062] In the above formula, i = 1, 2, 3, indicating that the emission direction of the laser in the optical path regulator corresponds to the positive directions of the three axes x, y, and z in the right-hand rectangular coordinate system, and different values ​​of j indicate different emission positions of the laser in the optical path regulator; P ij is the first coefficient matrix, ε ij is the laser propagation length variation coefficient matrix; due to the different values ​​of i and j, the corresponding P ij , ε ij are also different, and the corresponding Δl values ​​are different.

[0063] Furthermore, the temperature regulator regulates the temperature of the light-guiding medium in the optical path regulator in the following manner:

[0064] The volume change of the light-guiding medium due to thermal expansion effect is expressed as:

[0065] Δl=α·l·ΔT

[0066] In the above formula, ΔT is the temperature change;

[0067] The change in refractive index due to temperature change is expressed as:

[0068] Δn=ε·n·ΔT

[0069] In the above formula, ε is the temperature variation coefficient of the refractive index;

[0070] Therefore, the optical frequency change Δf2 due to temperature change is expressed as:

[0071] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the vehicle-mounted laser radar detection method described above are implemented.

[0072] A car is provided with the above-mentioned on-board laser radar based on dynamic adjustment of optical frequency.

[0073] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A vehicle-mounted laser radar based on dynamic adjustment of optical frequency, characterized in that: The laser radar includes a laser light source, an optical path regulator, a temperature regulator, an emission angle control module, an external light guiding medium and a laser radar controller; The laser light source is connected to the optical path regulator through an optical fiber, the optical path regulator is connected to the output angle control module through an optical fiber, and the external light-guiding medium is arranged at the light output position of the output angle control module; a temperature regulator is arranged outside the optical path regulator, the optical path regulator, the output angle control module, and the temperature regulator are all electrically connected to the laser radar controller, and the laser radar controller is electrically connected to the vehicle CAN bus; After the laser light source emits the laser, it is transmitted through the optical fiber and the optical path regulator, and is emitted from the emission angle control module. After emission, it is refracted by the external light-guiding medium to become the detection light; during the laser radar detection process, the emission angle control module adjusts the emission position of the laser according to the instructions of the laser radar controller, the laser light source adjusts the light intensity of the laser according to the instructions of the laser radar controller, the optical path regulator adjusts the propagation length of the laser in the light-guiding medium in the optical path regulator according to the instructions of the laser radar controller, and the temperature regulator adjusts the temperature of the light-guiding medium in the optical path regulator according to the instructions of the laser radar controller.

2. The vehicle-mounted laser radar based on dynamic adjustment of optical frequency according to claim 1, characterized in that: The optical path regulator is provided with a plurality of optical path regulating light gates; the optical path regulator controls the propagation path of the laser in the optical path regulator by controlling the opening and closing of different optical path regulating light gates.

3. The vehicle-mounted laser radar based on dynamic adjustment of optical frequency according to claim 1, characterized in that: The emission angle control module is provided with a plurality of emission light gates; the emission angle control module controls the emission position of the laser by controlling the opening and closing of different emission light gates.

4. A vehicle-mounted laser radar detection method implemented by using the vehicle-mounted laser radar based on dynamic adjustment of optical frequency according to any one of claims 1 to 3, characterized in that: The following steps are included: The laser radar starts working when it receives a call request signal from the vehicle's CAN bus; The laser emission angle is roughly adjusted by adjusting the laser emission position of the emission angle control module; The laser light source is used to adjust the light intensity of the laser, the optical path regulator is used to adjust the propagation length of the laser in the light-guiding medium in the optical path regulator, and the temperature regulator is used to adjust the temperature of the light-guiding medium in the optical path regulator; The effect of the changes in laser light intensity, propagation length in the light-guiding medium in the optical path regulator, and temperature of the light-guiding medium in the optical path regulator is integrated to change the optical frequency of the laser when it is incident on the external light-guiding medium, thereby achieving precise adjustment of the light emission angle; The above coarse adjustment and fine adjustment are performed cyclically until the laser radar continuously scans a certain range, and then the generated laser radar point cloud is obtained; Output detection results based on the LiDAR point cloud.

5. The vehicle-mounted laser radar detection method according to claim 4, characterized in that: The laser light source adjusts the laser light intensity in the following ways: Assume the emission intensity of the laser source is I B (t), I B (t) varies with time t, and the average light intensity of the laser incident on the optical fiber is I0 as determined by experiment; and then: In the above formula, K 12 , K 34 is the optical conduction power coupling coefficient corresponding to different optical paths in the optical path regulator, α is the power loss per unit length of the light-guiding medium, s is the number of reflections during laser propagation, is the initial phase of the laser, c is the propagation speed of light in a vacuum, n is the refractive index of the light-guiding medium, l is the laser propagation length, f is the light frequency, and m is the modulation coefficient.

6. The vehicle-mounted laser radar detection method according to claim 5, characterized in that: Based on the laser light source emission intensity I B (t), and the transfer function T of the laser inside the optical fiber is obtained r as follows: In the above formula, I B is the instantaneous emission intensity of the laser light source, θ is the phase of the laser, where R, T0, T a satisfy: Let m = 1, then: According to the above formula, if the output light intensity of the fiber ring is set to the extreme value, the output light phase should satisfy θ=2Nπ, where N is a natural number. Therefore, by adjusting K when designing the lidar 12 , K 34 The values ​​of , R are chosen so that the output light phase of the laser when it is transmitted from any optical path satisfies θ=2Nπ.

7. The vehicle-mounted laser radar detection method according to claim 6, characterized in that: The method of adjusting the total propagation length of the laser by the optical path regulator is as follows; Since the light frequency changes, it is expressed as: In the above formula, Δn is the change of n, and Δl is the change of l; When the influence of temperature and other uniform pressure fields is ignored, the following is satisfied: Δl=l·e z In the above formula, ε z is the laser propagation length variation coefficient; The corresponding relationship between the refractive index change Δn and the internal optical path setting mode of the optical path regulator is expressed as: In the above formula, i = 1, 2, 3, indicating that the emission direction of the laser in the optical path regulator corresponds to the positive directions of the three axes x, y, and z of the right-hand rectangular coordinate system, and different values ​​of j represent different emission positions of the laser in the optical path regulator; P ij is the first coefficient matrix, ε ij is the laser propagation length variation coefficient matrix; due to the different values ​​of i and j, the corresponding P ij , ε ij are also different, and the corresponding Δl values ​​are different.

8. The vehicle-mounted laser radar detection method according to claim 7, characterized in that: The specific method of the temperature regulator regulating the temperature of the light-guiding medium in the optical path regulator is as follows; The volume change of the light-guiding medium due to thermal expansion effect is expressed as: Δl=α·l·ΔT In the above formula, ΔT is the temperature change; The change in refractive index due to temperature change is expressed as: Δn=ε·n·ΔT In the above formula, ε is the temperature variation coefficient of the refractive index; Therefore, the optical frequency change Δf2 due to temperature change is expressed as:

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the vehicle-mounted laser radar detection method described in any one of claims 4-8 are implemented.

10. An automobile, characterized in that: The automobile is provided with a vehicle-mounted laser radar based on dynamic adjustment of optical frequency as described in any one of claims 1-3.

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