Laser receiving module, lidar and laser ranging method

Abstract

This application proposes a laser receiving module, a lidar, and a laser ranging method. The laser receiving module includes a photoelectric detection component, a discharge circuit, and a ranging circuit. During the period from the emission of the laser signal to the arrival of other stray light paths at the photoelectric detection component, the discharge circuit is triggered to conduct, discharging the current signal generated by the photoelectric detection component to eliminate the ranging influence of invalid laser echo signals. After this preset period, the ranging circuit determines the distance information based on the current signal generated by the photoelectric detection component. The current signal after the preset period only contains the laser echo signal reflected by normal photoelectric reflection, reducing the ranging blind zone at close range and improving ranging accuracy.

Description

Technical Field

[0001] This application belongs to the field of lidar technology, and particularly relates to a laser receiving module, lidar, and laser ranging method. Background Technology

[0002] LiDAR ranging systems are increasingly being used in applications such as autonomous driving.

[0003] LiDAR determines distance information based on the time difference between laser emission and laser reception. However, in actual use, due to optical design limitations, the emitted light may be reflected directly to the laser receiving module through the inner wall of the lens barrel or impurities on the mirror surface. The reflected echo signal and the effective laser echo signal form a virtual echo signal, which increases the near-range blind zone distance of the LiDAR. Summary of the Invention

[0004] The purpose of this application is to provide a laser receiving module that aims to solve the problem of large blind spots at close range in traditional lidar.

[0005] A first aspect of this application provides a laser receiving module, comprising:

[0006] A photoelectric detection component is used to receive the reflected laser echo signal and convert it into a current signal;

[0007] A discharge circuit, connected to the photoelectric detection component, is used to trigger conduction within a preset time period to discharge the current signal generated by the photoelectric detection component, and to trigger shutdown after the preset time period, wherein the preset time period is the period during which the laser signal reaches the photoelectric detection component through stray optical paths other than the ranging optical path;

[0008] A ranging circuit, connected to the photoelectric detection component, is used to determine distance information based on the current signal after the preset time period.

[0009] Optionally, the photodetector assembly includes at least one of an avalanche diode, a silicon photomultiplier tube, a single-photon avalanche diode, and a photodiode.

[0010] Optionally, the ranging circuit includes:

[0011] A transimpedance amplifier circuit, connected to the photodetector component, is used to convert the current signal into a voltage signal and amplify it to obtain an amplified voltage signal.

[0012] The processing circuit, connected to the transimpedance amplifier circuit, is used to determine distance information based on the amplified voltage signal.

[0013] Optionally, the discharge circuit includes a discharge switch, a first terminal of which is connected to the photoelectric detection component, a second terminal of which is grounded, and a controlled terminal of which is used to receive control signals.

[0014] Optionally, the laser receiving module further includes:

[0015] A signal suppression circuit is provided, which is connected to the discharge switch, and is used to suppress interference signals generated when the discharge switch is switched on and off.

[0016] Optionally, the signal suppression circuit includes a capacitor and a first resistor;

[0017] The first end of the capacitor is connected to the photoelectric detection component, the second end of the capacitor is connected to the first end of the discharge switch, the second end of the discharge switch is grounded, the controlled end of the discharge switch is connected to the first end of the first resistor, and the second end of the first resistor is used to receive the control signal.

[0018] A second aspect of this application provides a lidar, including a laser emitting module, a controller, and a laser receiving module as described above, wherein the controller is connected to both the laser emitting module and the laser receiving module.

[0019] The controller is used to output a drive signal to the laser emitting module to drive the laser emitting module to emit a laser signal, and to output a discharge control signal to the discharge circuit of the laser receiving module during a preset time period.

[0020] Optionally, the laser emitting module includes:

[0021] A laser emitting assembly, wherein the laser emitting assembly is used to receive and emit the laser signal;

[0022] A laser driving circuit, connected to the laser emitting component, is used to trigger the output of driving power to the laser emitting component according to the driving signal.

[0023] Optionally, the laser emitting assembly includes a laser.

[0024] A third aspect of this application provides a laser ranging method, comprising:

[0025] Emit laser signals;

[0026] The current signal generated by the photoelectric detection component is discharged within a preset time period, wherein the preset time period is the time period during which the laser signal reaches the photoelectric detection component through stray optical paths other than the ranging optical path;

[0027] After a preset time period, distance information is determined based on the current signal generated by the photoelectric detection component.

[0028] The beneficial effects of this application embodiment compared with the prior art are as follows: The laser receiving module described above consists of a photoelectric detection component, a discharge circuit, and a ranging circuit. During the period from the emission of the laser signal to the arrival of other stray light paths at the photoelectric detection component, the discharge circuit is triggered to conduct, discharging the current signal generated by the photoelectric detection component, eliminating the ranging influence of invalid laser echo signals, and after this preset period, the ranging circuit determines the distance information based on the current signal generated by the photoelectric detection component. The current signal after the preset period only contains the laser echo signal reflected back by normal photoelectric reflection, reducing the ranging blind zone at close range and improving the ranging accuracy. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a first type of laser receiving module provided in an embodiment of this application;

[0030] Figure 2 A schematic diagram of the discharge waveform of the laser receiving module provided in the embodiments of this application;

[0031] Figure 3 This is a first circuit diagram of a laser receiving module provided in an embodiment of this application;

[0032] Figure 4 This is a second circuit diagram of a laser receiving module provided in an embodiment of this application;

[0033] Figure 5 This is a schematic diagram of a third type of laser receiving module provided in an embodiment of this application;

[0034] Figure 6 This is a schematic diagram of a first type of lidar module provided in an embodiment of this application;

[0035] Figure 7 This is a schematic diagram of a second type of lidar module provided in an embodiment of this application;

[0036] Figure 8 This is a schematic flowchart of the laser ranging method provided in the embodiments of this application. Detailed Implementation

[0037] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0039] The first aspect of this application provides a laser receiving module 100 for receiving laser signals and determining distance information based on the laser signals, such as... Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of the laser receiving module 100 provided in an embodiment of this application. In this embodiment, the laser receiving module 100 includes:

[0040] The photoelectric detection component 10 is used to receive the reflected laser echo signal and convert it into a current signal;

[0041] The discharge circuit 20 is connected to the photoelectric detection component 10 and is used to trigger conduction within a preset time period T to discharge the current signal generated by the photoelectric detection component 10, and to trigger shutdown after the preset time period T. The preset time period T is the time period during which the laser signal reaches the photoelectric detection component 10 through stray optical paths other than the ranging optical path.

[0042] The ranging circuit 30 is connected to the photoelectric detection component 10 and is used to determine the distance information based on the current signal after a preset time period T.

[0043] In this embodiment, the discharge circuit 20 and the ranging circuit 30 are both connected to the signal terminals of the photoelectric detection component 10. When performing laser ranging, the laser emitting component 210 emits laser signals under control. There are two parts of laser echo signals emitted to the photoelectric detection component 10. One part is an invalid laser echo signal reflected by other stray optical paths inside the lidar. The other part is an effective laser echo signal emitted by the laser signal through the normal optical path to the object under test 1 and then reflected back to the photoelectric detection component 10 by the object under test 1.

[0044] Among them, such as Figure 2As shown, S1 represents the emitted waveform of the laser signal, and S2 represents the current signal generated by the photoelectric detection component 10. In S2, the first echo is the current signal corresponding to the invalid laser echo signal reflected internally, and the second echo is the current signal corresponding to the valid laser echo signal reflected. S3 is the operating waveform of the discharge circuit 20. Because the invalid laser echo signal reflected by other stray light paths inside the lidar arrives at the photoelectric detection component 10 before the valid laser echo signal, the controller 300 controls the discharge circuit 20 to be turned on within a preset time period T during which the laser signal is reflected to the photoelectric detection component 10 by other stray light paths inside the lidar. In order to eliminate the invalid laser echo signal, the controller 300 controls the discharge circuit 20 to be turned on. During this preset time period T, the discharge circuit 20 transmits the invalid laser echo signal received by the photoelectric detection component 10. The current signal generated by the laser echo signal is discharged to ground and does not flow into the subsequent ranging circuit 30, thus eliminating the ranging influence of invalid laser echo signals. After the preset time period T is exceeded, the controller 300 controls the discharge circuit 20 to close and stop the discharge operation. At this time, the current signal generated by the photoelectric detection component 10 receiving the valid laser echo signal flows into the subsequent ranging circuit 30. The ranging circuit 30 processes the signal and determines the distance information based on the emission and reception time of the laser signal. The current signal after the preset time period T only contains the current signal corresponding to the laser echo signal reflected back by normal photoelectric reflection, that is, the current signal corresponding to the second valid reflected laser echo signal in S2. There is no current signal corresponding to the laser echo signal reflected back internally, which reduces the ranging blind zone at close range and improves the ranging accuracy.

[0045] By adjusting the duration of the preset time period T, the current ratio of the two laser echo signals entering the subsequent ranging circuit 30 can be effectively improved, thereby increasing the amplitude of the effective laser echo signal. The duration of the preset time period T is obtained based on actual detection or calculation, and it is related to the internal structure of different lidars and the distance to the object 1 under test. It can be set according to actual needs.

[0046] The photoelectric detection component 10 can be selected from different types of photoelectric detectors and corresponding circuits, such as... Figure 3 As shown, the photoelectric detection component 10 includes at least one of an avalanche diode, a silicon photomultiplier tube, a single-photon avalanche diode, and a photodiode. D1 represents the corresponding type of photoelectric detector. After receiving the photoelectric echo signal, the current signal generated by the photoelectric detector is sent to the subsequent discharge circuit 20 and the ranging circuit 30 through the connection node with the second resistor R2. The first part of the current signal is discharged to ground through the discharge circuit 20, and the second part of the current signal is output to the ranging circuit 30 to determine the distance information.

[0047] The discharge circuit 20 can be selected with a corresponding switching structure, such as... Figure 3As shown, the discharge circuit 20 includes a discharge switch K1. The first terminal of the discharge switch K1 is connected to the photoelectric detection component 10, and the second terminal of the discharge switch K1 is grounded. During a preset time period T when the laser signal is reflected to the photoelectric detection component 10 by other stray light paths inside the lidar, the controller 300 controls the discharge switch K1 to conduct. During this preset time period T, the discharge switch K1 discharges the current signal generated by the invalid laser echo signal received by the photoelectric detection component 10 to ground, preventing it from flowing into the subsequent ranging circuit 30, thus eliminating the ranging influence of the invalid laser echo signal. After the preset time period T is exceeded, the controller 300... When the discharge switch K1 is closed, the discharge operation ceases. At this time, the current signal generated by the photoelectric detection component 10 receiving the valid laser echo signal flows into the subsequent ranging circuit 30. The ranging circuit 30 processes the signal and determines the distance information based on the emission and reception time of the laser signal. The current signal after the preset time period T only contains the current signal corresponding to the laser echo signal reflected back by normal photoelectric means, that is, the current signal corresponding to the second valid reflected laser echo signal in S2. There is no current signal corresponding to the laser echo signal reflected back internally, which reduces the blind zone of the near-range ranging and improves the ranging accuracy.

[0048] Among them, the discharge switch K1 can be selected from switching devices such as relays, MOSFETs, and transistors, and the specific type is not limited.

[0049] In this case, because the discharge switch K1 has an interference signal caused by parasitic capacitance during the time it is turned on to turned off, in order to suppress this signal, such as... Figure 4 As shown, optionally, the laser receiving module 100 further includes:

[0050] The signal suppression circuit 40 is connected to the discharge switch K1. The signal suppression circuit 40 is used to suppress the interference signal generated when the discharge switch K1 is switched on and off, so as to prevent the interference signal from flowing into the subsequent ranging circuit 30, thereby improving the ranging accuracy and reducing the near-range blind zone.

[0051] The signal suppression circuit 40 can optionally employ corresponding optocouplers, capacitors, or other structures. For example, Figure 4 As shown, the signal suppression circuit 40 includes a capacitor C1 and a first resistor R1;

[0052] The first terminal of capacitor C1 is connected to the photodetector component 10, and the second terminal of capacitor C1 is connected to the first terminal of the discharge switch K1. The second terminal of the discharge switch K1 is grounded, and the controlled terminal of the discharge switch K1 is connected to the first terminal of the first resistor R1. The second terminal of the first resistor R1 is used to receive the drive signal. By adjusting the resistance value of the first resistor R1 and the capacitance value of capacitor C1, the magnitude of the interference signal can be optimized. In a simulation experiment, when the discharge switch K1 is a MOSFET, and the resistance value of the first resistor R1 is 1K, the interference signal generated by coupling during the MOSFET turn-off process is significantly reduced. The specific values ​​of the first resistor R1 and capacitor C1 can be determined by simulation or actual measurement according to the type of discharge switch K1.

[0053] The ranging circuit 30 can be configured with a transimpedance amplifier, analog-to-digital converter, or other structures. Optionally, for example... Figure 5 As shown, the ranging circuit 30 includes:

[0054] The transimpedance amplifier circuit 31 is connected to the photodetector component 10 and is used to convert the current signal into a voltage signal and amplify it to obtain the amplified voltage signal.

[0055] The processing circuit 32 is connected to the transimpedance amplifier circuit 31 and is used to determine the distance information based on the amplified voltage signal.

[0056] In this embodiment, the transimpedance amplifier circuit 31 is connected between the photoelectric detection component 10 and the processing circuit 32. After a preset time period T, the transimpedance amplifier circuit 31 converts the effective current signal generated by the photoelectric detection component 10 from current to voltage. The processing circuit 32 performs corresponding processing such as digital-to-analog conversion, amplification, and detection to obtain the corresponding ranging data. The distance information is determined based on the ranging data. The transimpedance amplifier circuit 31 can be selected from structures such as transimpedance amplifiers, resistors and amplifiers, etc., according to functional requirements. The processing circuit 32 can be selected from structures such as analog-to-digital converters and detection circuits. The specific structure is not limited.

[0057] The beneficial effects of this application embodiment compared with the prior art are as follows: The laser receiving module 100 described above is composed of a photoelectric detection component 10, a discharge circuit 20, and a ranging circuit 30. During the period from the emission of the laser signal to the arrival of other stray light paths at the photoelectric detection component 10, the discharge circuit 20 is triggered to conduct, discharging the current signal generated by the photoelectric detection component 10, eliminating the ranging influence of invalid laser echo signals, and after the preset period, the ranging circuit 30 determines the distance information based on the current signal generated by the photoelectric detection component 10. The current signal after the preset period T only contains the current signal corresponding to the laser echo signal reflected back by normal photoelectric reflection, reducing the ranging blind zone at close range and improving the ranging accuracy.

[0058] This application also proposes a lidar, such as Figure 6As shown, the lidar includes a laser emitting module 200, a controller 300, and a laser receiving module 100. The specific structure of the laser receiving module 100 is as described in the above embodiments. Since this lidar adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0059] The controller 300 is connected to the laser emitting module 200 and the laser receiving module 100, respectively.

[0060] The controller 300 is used to output a drive signal to the laser emitting module 200 to drive the laser emitting module 200 to emit a laser signal, and to output a discharge control signal to the discharge circuit 20 of the laser receiving module 100 during a preset time period T.

[0061] In this embodiment, the controller 300 controls the laser emission and the discharge circuit 20. When ranging begins, the controller 300 controls the laser emission module 200 to emit a laser signal. During a preset time period T, when the laser signal is reflected by other stray light paths within the lidar to the photoelectric detection component 10, the controller 300 controls the discharge circuit 20 to conduct in order to eliminate the invalid laser echo signal. During this preset time period T, the discharge circuit 20 discharges the current signal generated by the invalid laser echo signal received by the photoelectric detection component 10 to ground, preventing it from flowing into the subsequent ranging circuit 30, thus eliminating the invalid signal. The laser echo signal affects ranging. When the preset time period T is exceeded, the controller 300 controls the discharge circuit 20 to close and stop the discharge operation. At this time, the current signal generated by the photoelectric detection component 10 receiving the valid laser echo signal flows into the subsequent ranging circuit 30. The ranging circuit 30 processes the signal and determines the distance information based on the emission and reception time of the laser signal. The current signal after the preset time period T only contains the current signal corresponding to the laser echo signal reflected back by normal photoelectric means, and there is no current signal corresponding to the laser echo signal reflected back internally. This reduces the ranging blind zone at close range and improves ranging accuracy.

[0062] The controller 300 can be equipped with microcontrollers, MCUs, FPGAs, or other modules, with no specific type restrictions.

[0063] The laser emitting module 200 can be selected with a corresponding type of laser emitting component 210, such as... Figure 7As shown, optionally, the laser emitting module 200 includes a laser emitting component 210 and a laser driving circuit 220. The laser emitting component 210 is used to receive power and emit laser signals. The laser driving circuit 220 is connected to the laser emitting component 210 and is used to trigger the output of driving power to the laser emitting component 210 according to the driving signal. The laser emitting component 210 can select a laser of a corresponding type. The laser driving circuit 220 can select a charging and discharging circuit of a corresponding structure. The charging and discharging circuit charges and discharges according to the received driving signal and controls the laser to emit laser signals at a corresponding angle according to the corresponding timing sequence.

[0064] This application also proposes a laser ranging method, such as... Figure 8 As shown, the laser ranging method includes the following steps:

[0065] Step S11: Emit a laser signal;

[0066] Step S12: Discharge the current signal generated by the photoelectric detection component 10 within a preset time period T, wherein the preset time period T is the time period during which the laser signal reaches the photoelectric detection component 10 through stray optical paths other than the ranging optical path.

[0067] Step S13: After a preset time period T, determine the distance information based on the current signal generated by the photoelectric detection component 10.

[0068] In this embodiment, the discharge operation is completed by the discharge circuit 20 connected to the photoelectric detection component 10, and the distance information determination operation is completed by the ranging circuit 30. Both the discharge circuit 20 and the ranging circuit 30 are connected to the signal terminal of the photoelectric detection component 10. When performing laser ranging, the laser emitting component 210 is first controlled to emit a laser signal. There are two parts of the laser echo signal emitted to the photoelectric detection component 10. One part is the invalid laser echo signal reflected by other stray optical paths inside the laser radar. The other part is the valid laser echo signal emitted by the laser signal through the normal optical path to the object under test 1 and then reflected back to the photoelectric detection component 10 by the object under test 1.

[0069] like Figure 2As shown, S1 represents the emitted waveform of the laser signal, and S2 represents the current signal generated by the photoelectric detection component 10. In S2, the first echo is the current signal corresponding to the invalid laser echo signal reflected internally, the second echo is the current signal corresponding to the valid laser echo signal, and S3 is the operating waveform of the discharge circuit 20. Since the invalid laser echo signal reflected by other stray light paths inside the lidar arrives at the photoelectric detection component 10 before the valid laser echo signal, within a preset time period T during which the laser signal is reflected to the photoelectric detection component 10 by other stray light paths inside the lidar, the discharge circuit 20 is controlled to conduct in order to eliminate the invalid laser echo signal. During this preset time period T, the discharge circuit 20 receives the invalid laser echo signal from the photoelectric detection component 10. The current signal generated by the signal is discharged to ground and does not flow into the subsequent ranging circuit 30, eliminating the ranging influence of invalid laser echo signals. When the preset time period T is exceeded, the discharge circuit 20 is shut down and the discharge operation stops. At this time, the current signal generated by the photoelectric detection component 10 receiving the valid laser echo signal flows into the subsequent ranging circuit 30. The ranging circuit 30 processes the signal and determines the distance information based on the emission and reception time of the laser signal. The current signal after the preset time period T only contains the current signal corresponding to the laser echo signal reflected back by normal photoelectric means, that is, the current signal corresponding to the second valid reflected laser echo signal in S2. There is no current signal corresponding to the laser echo signal reflected back internally, which reduces the ranging blind zone at close range and improves the ranging accuracy.

[0070] By adjusting the duration of the preset time period T, the current ratio of the two laser echo signals entering the subsequent ranging circuit 30 can be effectively improved, thereby increasing the amplitude of the effective laser echo signal. The duration of the preset time period T is obtained based on actual detection or calculation, and it is related to the internal structure of different lidars and the distance to the object 1 under test. It can be set according to actual needs.

[0071] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0072] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A laser receiving module, characterized in that, include: A photoelectric detection component is used to receive the reflected laser echo signal and convert it into a current signal; A discharge circuit, connected to the photoelectric detection component, is used to trigger conduction within a preset time period to discharge the current signal generated by the photoelectric detection component, and to trigger shutdown after the preset time period, wherein the preset time period is the period during which the laser signal reaches the photoelectric detection component through stray optical paths other than the ranging optical path; A ranging circuit, connected to the photoelectric detection component, is used to determine distance information based on the current signal after the preset time period; In this process, invalid laser echo signals reflected by other stray optical paths within the lidar arrive at the photoelectric detection component before valid laser echo signals.

2. The laser receiving module as described in claim 1, characterized in that, The photoelectric detection component includes at least one of an avalanche diode, a silicon photomultiplier tube, a single-photon avalanche diode, and a photodiode.

3. The laser receiving module as described in claim 1, characterized in that, The ranging circuit includes: A transimpedance amplifier circuit, connected to the photodetector component, is used to convert the current signal into a voltage signal and amplify it to obtain an amplified voltage signal. The processing circuit, connected to the transimpedance amplifier circuit, is used to determine distance information based on the amplified voltage signal.

4. The laser receiving module as described in claim 1, characterized in that, The discharge circuit includes a discharge switch, the first end of which is connected to the photoelectric detection component, the second end of which is grounded, and the controlled end of which is used to receive control signals.

5. The laser receiving module as described in claim 4, characterized in that, The laser receiving module further includes: A signal suppression circuit is provided, which is connected to the discharge switch, and is used to suppress interference signals generated when the discharge switch is switched on and off.

6. The laser receiving module as described in claim 5, characterized in that, The signal suppression circuit includes a capacitor and a first resistor; The first end of the capacitor is connected to the photoelectric detection component, the second end of the capacitor is connected to the first end of the discharge switch, the second end of the discharge switch is grounded, the controlled end of the discharge switch is connected to the first end of the first resistor, and the second end of the first resistor is used to receive the control signal.

7. A lidar, characterized in that, It includes a laser emitting module, a controller, and a laser receiving module as described in any one of claims 1 to 6, wherein the controller is connected to the laser emitting module and the laser receiving module respectively; The controller is used to output a drive signal to the laser emitting module to drive the laser emitting module to emit a laser signal, and to output a discharge control signal to the discharge circuit of the laser receiving module during a preset time period.

8. The lidar as described in claim 7, characterized in that, The laser emitting module includes: A laser emitting assembly, wherein the laser emitting assembly is used to receive and emit the laser signal; A laser driving circuit, connected to the laser emitting component, is used to trigger the output of driving power to the laser emitting component according to the driving signal.

9. The lidar as described in claim 8, characterized in that, The laser emitting assembly includes a laser.

10. A laser ranging method, characterized in that, include: Emit laser signals; The current signal generated by the photoelectric detection component is discharged within a preset time period, wherein the preset time period is the time period during which the laser signal reaches the photoelectric detection component through stray optical paths other than the ranging optical path; After a preset time period, distance information is determined based on the current signal generated by the photoelectric detection component; In this process, invalid laser echo signals reflected by other stray optical paths within the lidar arrive at the photoelectric detection component before valid laser echo signals.

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