Laser radar calibration method and device

Abstract

Embodiments of the present invention provide a laser radar calibration method and apparatus, relating to the field of laser scanning technology. The method comprises: detecting the phase of a laser radar's laser emission module and obtaining a detection time for detecting the phase; and adjusting the movement speed of the laser emission module based on the detected phase and the detection time, so that the phase of the laser emission module is a preset phase at each preset time. Application of the laser radar calibration scheme provided in embodiments of the present invention can improve the accuracy of fusing point cloud data collected by multiple laser radars.

Description

Technical Field

[0001] The present invention relates to the field of laser scanning technology, and in particular to a laser radar calibration method and device. Background Art

[0002] The mechanical rotating laser radar includes a laser emitting module, which is used to emit laser to the outside world and receive laser reflected from the outside world. During the operation of the mechanical rotating laser radar, the laser emitting module rotates around the rotation axis. The laser radar generates a frame of point cloud data based on the laser information received within an acquisition cycle.

[0003] Since mechanical errors exist between the various components of the mechanical rotating lidar, which has a significant impact on the accuracy of subsequent multi-sensor data fusion, the lidar needs to be calibrated. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a laser radar calibration method and apparatus to improve the accuracy of point cloud data fusion collected by multiple laser radars. The specific technical solution is as follows:

[0005] In a first aspect, an embodiment of the present invention provides a laser radar calibration method, the method comprising:

[0006] Detecting the phase of a laser emission module of a laser radar and obtaining a detection time of detecting the phase;

[0007] Based on the detected phase and the detection moment, the movement speed of the laser emission module is adjusted so that the phase of the laser emission module is a preset phase at each preset moment, wherein the preset moment is set according to the acquisition cycle of the laser radar.

[0008] In one embodiment of the present invention, adjusting the movement speed of the laser emission module based on the detected phase and the detection time includes:

[0009] Based on the difference between the detected phase and the preset phase, and the time difference between the detection moment and the most recent preset moment, the target speed of the laser emission module is calculated, and the movement speed of the laser emission module is adjusted to the target speed, wherein the most recent preset moment is a preset moment after the detection moment and adjacent to the detection moment.

[0010] In one embodiment of the present invention, the preset phase is a zero phase.

[0011] In one embodiment of the present invention, the laser radars are multiple laser radars in the same scene, and the multiple laser radars are timed by the same clock device.

[0012] In one embodiment of the present invention, the clock device is a GPS clock device.

[0013] In one embodiment of the present invention, there are multiple laser radars, and the method further includes:

[0014] Determine a first laser radar from the multiple laser radars, and determine data collected by the first laser radar with a first frame time as first point cloud data;

[0015] Selecting data collected by the remaining laser radars with a frame time of the second moment as the second point cloud data; wherein the time difference between the first moment and the second moment does not exceed the preset time difference;

[0016] The first point cloud data and the second point cloud data are fused.

[0017] In one embodiment of the present invention, the number of the laser radars is multiple, including a reference radar and at least one third laser radar, all of which have the same acquisition period. The adjusting of the movement speed of the laser emission module based on the detected phase and the detection time so that the phase of the laser emission module at each preset time is a preset phase includes:

[0018] According to the reference phase of the reference radar at the reference time, the movement speed of the laser emission module of the third laser radar is adjusted so that the phase of the laser emission module of the third laser radar at the preset time is the preset phase, wherein,

[0019] The reference time corresponds to the preset time;

[0020] The reference phase corresponds to the preset phase in a one-to-one manner.

[0021] In a second aspect, an embodiment of the present invention further provides a laser radar calibration device, the device comprising:

[0022] A phase detection module is used to detect the phase of the laser emission module of the laser radar and obtain a detection time of the phase;

[0023] A speed adjustment module is used to adjust the movement speed of the laser emission module based on the detected phase and the detection time, so that the phase of the laser emission module is a preset phase at each preset time, wherein the preset time is set according to the acquisition cycle of the laser radar.

[0024] In one embodiment of the present invention, the speed adjustment module is specifically configured to:

[0025] Based on the difference between the detected phase and the preset phase, and the time difference between the detection moment and the most recent preset moment, the target speed of the laser emission module is calculated, and the movement speed of the laser emission module is adjusted to the target speed, so that the phase of the laser emission module at each preset moment is the preset phase, wherein the most recent preset moment is a preset moment after the detection moment and adjacent to the detection moment.

[0026] In one embodiment of the present invention, the preset phase is a zero phase.

[0027] In one embodiment of the present invention, the laser radars are multiple laser radars in the same scene, and the multiple laser radars are timed by the same clock device.

[0028] In one embodiment of the present invention, the clock device is a GPS clock device.

[0029] In one embodiment of the present invention, there are multiple laser radars, and the device further includes:

[0030] A first data acquisition module is used to determine a first laser radar from multiple laser radars, and determine data collected by the first laser radar with a first frame time as first point cloud data;

[0031] The second data acquisition module is used to select data collected by the remaining laser radars and having a frame time of the second moment as the second point cloud data; wherein the time difference between the first moment and the second moment does not exceed the preset time difference;

[0032] A data fusion module is used to fuse the first point cloud data and the second point cloud data.

[0033] In one embodiment of the present invention, the number of the laser radars is multiple, including a reference radar and at least one third laser radar, all of which have the same acquisition period;

[0034] The speed adjustment module is specifically used to:

[0035] According to the reference phase of the reference radar at the reference time, the movement speed of the laser emission module of the third laser radar is adjusted so that the phase of the laser emission module of the third laser radar at the preset time is the preset phase, wherein,

[0036] The reference time corresponds to the preset time;

[0037] The reference phase corresponds to the preset phase in a one-to-one manner.

[0038] In a third aspect, an embodiment of the present invention further provides an electronic device, comprising a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus;

[0039] Memory for storing computer programs;

[0040] The processor is used to implement the steps of the laser radar calibration method described in any one of the first aspects above when executing the program stored in the memory.

[0041] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the laser radar calibration method described in any one of the first aspects are implemented.

[0042] Beneficial effects of the embodiments of the present invention:

[0043] Since the error between the time required for the laser emission module to rotate one circle and the acquisition cycle of the laser radar is usually small, the smaller error has little impact on the point cloud data collected by the laser radar. However, during the operation of the laser radar, the above error will continue to accumulate as the working time of the laser radar increases, and eventually have a greater impact on the point cloud data collected by the laser radar, reducing the accuracy of the point cloud data collected by the laser radar. It can be seen from the above that when the scheme provided by the embodiment of the present invention is used to calibrate the laser radar, the preset moment is set according to the acquisition cycle of the laser radar, and the time difference between two adjacent preset moments is the duration corresponding to one or more acquisition cycles. The speed of the laser emission module is adjusted so that the phase of the laser emission module at each preset moment is the preset phase. It can be understood that the phase of the laser emission module is reset every one or more acquisition cycles, thereby avoiding the above error from accumulating as the working time of the laser radar increases, reducing the impact of the above error on the quality of the laser radar point cloud data, especially the impact on the accuracy of the point cloud data in the multi-sensor fusion scenario. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0045] Figure 1 A schematic diagram of a flow chart of a first laser radar calibration method provided in an embodiment of the present invention;

[0046] Figure 2 A schematic diagram of a flow chart of a second laser radar calibration method provided in an embodiment of the present invention;

[0047] Figure 3 A schematic diagram of a flow chart of a third laser radar calibration method provided in an embodiment of the present invention;

[0048] Figure 4 A schematic diagram of a fourth laser radar calibration method according to an embodiment of the present invention;

[0049] Figure 5 A schematic structural diagram of a first laser radar calibration device provided in an embodiment of the present invention;

[0050] Figure 6 A schematic structural diagram of a second laser radar calibration device provided in an embodiment of the present invention;

[0051] Figure 7 A schematic structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 based on the present invention are within the scope of protection of the present invention.

[0053] See also Figure 1 , Figure 1 A flowchart of a first laser radar calibration method is provided for an embodiment of the present invention. The method includes the following steps S101-S102.

[0054] Step S101: Detect the phase of the laser emission module of the laser radar and obtain the detection time of the detection phase.

[0055] The phase of the laser radar transmitting module can be defined as the rotation angle of the laser radar transmitting module relative to the initial zero phase position. It can be pre-calibrated or the position of the laser module when the radar starts working can be used as zero phase.

[0056] In one embodiment of the present invention, the laser radar may include a measurement module for detecting the phase of a laser emission module. When the laser emission module emits laser light, the measurement module can be used to detect the phase of the laser emission module, thereby obtaining the phase. The moment the measurement module performs the detection is recorded as the detection moment. The detection can be performed in real time or at fixed intervals.

[0057] In one embodiment of the present invention, the measurement module is an inertial measurement mechanism.

[0058] In addition, in addition to using the above-mentioned measurement module to detect the phase of the laser emission module, the phase of the laser emission module can also be detected by existing phase measurement technology, which will not be described in detail here.

[0059] Step S102: Based on the detected phase and the detection time, adjusting the movement speed of the laser emitting module so that the phase of the laser emitting module is a preset phase at each preset time.

[0060] Among them, the above-mentioned preset time is set according to the acquisition cycle of the laser radar.

[0061] The preset time can be set in advance, and the timing starting point can also be the moment when the laser radar starts working.

[0062] For example, the preset time can be set to 1 second, 2 seconds, etc. after the laser radar starts working.

[0063] In one embodiment of the present invention, a preset time may be set every one or more collection cycles.

[0064] For example, if the acquisition cycle is 100 milliseconds, a preset time can be set every 10 acquisition cycles. The preset time is an integer of 1 second, 2 seconds, etc. At this time, the time difference between any two adjacent preset times is the same.

[0065] In addition, the time differences between any two adjacent preset moments may also be different.

[0066] In the above example of setting the preset time, the preset time may also be 1 second, 2 seconds, 2.5 seconds, or other seconds set according to the acquisition cycle.

[0067] The above-mentioned preset phase can be any pre-set phase. The preset phase can be set to zero phase, Phase, etc.

[0068] The movement speed of the laser emitting module may be the angular velocity of the laser emitting module rotating around its axis, or may be the linear velocity of the laser emitting module.

[0069] Specifically, a preset phase may be determined in advance, and after obtaining the detected phase and detection time, the movement speed of the laser emission module may be adjusted based on the detected phase, detection time and the determined phase.

[0070] The specific implementation method of adjusting the movement speed of the laser emission module based on the detected phase and detection time can be found in the subsequent embodiments and will not be described in detail here.

[0071] Since the error between the time required for the laser emission module to rotate one circle and the acquisition cycle of the laser radar is usually small, the smaller error has little impact on the point cloud data collected by the laser radar. However, during the operation of the laser radar, the above error will continue to accumulate as the working time of the laser radar increases, and eventually have a greater impact on the point cloud data collected by the laser radar, reducing the accuracy of the point cloud data collected by the laser radar. It can be seen from the above that when the scheme provided by the embodiment of the present invention is used to calibrate the laser radar, the preset moment is set according to the acquisition cycle of the laser radar, and the time difference between two adjacent preset moments is the duration corresponding to one or more acquisition cycles. The speed of the laser emission module is adjusted so that the phase of the laser emission module at each preset moment is the preset phase. It can be understood that the phase of the laser emission module is reset every one or more acquisition cycles, thereby avoiding the above error from accumulating as the working time of the laser radar increases, reducing the impact of the above error on the quality of the laser radar point cloud data, especially the impact on the accuracy of the point cloud data in the multi-sensor fusion scenario.

[0072] In one embodiment of the present invention, see Figure 2 , provides a flow chart of a second lidar calibration method. In this embodiment, the above step S102 can be implemented by the following step S102A.

[0073] Step S102A: Calculate the target speed of the laser emission module based on the difference between the detected phase and the preset phase, and the time difference between the detection moment and the most recent preset moment, and adjust the movement speed of the laser emission module to the target speed so that the phase of the laser emission module is the preset phase at each preset moment.

[0074] The latest preset time is a preset time after the detection time and adjacent to the detection time.

[0075] For example, the above-mentioned preset time can be set to an integer second such as 1 second or 2 seconds. At this time, if the above-mentioned detection time is 0.9 seconds, the above-mentioned latest preset time is 1 second after 0.9 seconds and adjacent to 0.9 seconds among each preset time; if the above-mentioned detection time is 1.1 seconds, the above-mentioned latest preset time is 2 seconds after 1.1 seconds and adjacent to 1.1 seconds among each preset time.

[0076] Specifically, the difference between the detected phase and the preset phase, as well as the time difference between the detection moment and the most recent preset moment, can be calculated. Based on the calculated phase difference and time difference, the target speed of the laser emission module can be calculated, and then the movement speed of the laser emission module can be adjusted to the calculated target speed.

[0077] In one embodiment of the present invention, when calculating the difference between the detected phase and the preset phase, the detected phase may be subtracted from the preset phase to obtain a calculation result after subtraction as the difference between the detected phase and the preset phase.

[0078] In addition, the inertial measurement unit in the lidar can also be used to calculate the difference between the detected phase and the preset phase.

[0079] When calculating the time difference, the detection time may be subtracted from the latest preset time, and the calculated result is the time difference between the detection time and the latest preset time.

[0080] In one embodiment of the present invention, after obtaining the above-mentioned difference and time difference, the above-mentioned difference can be converted into the position difference between the current phase of the laser emission module and the preset phase, and the position difference is divided by the time difference. The result of the division is the target speed of the laser emission module, and the movement speed of the laser emission module is adjusted to the target speed.

[0081] If the above-mentioned position difference is expressed by the above-mentioned arc, the calculated target speed is the target linear speed of the laser emission module, and the adjusted movement speed is also the linear speed of the laser emission module; if the above-mentioned position difference is expressed by angle, the calculated target speed is the target angular speed of the laser emission module, and the adjusted movement speed is also the angular speed of the laser emission module.

[0082] In this case, when the laser emission module reaches the preset phase at the latest preset moment, the movement speed of the laser emission module is the calculated target speed.

[0083] In another embodiment of the present invention, the current movement speed of the laser emission module can be obtained, and the acceleration of the laser emission module can be calculated based on the obtained current movement speed, the above-mentioned difference and the time difference. The target speed at different moments is calculated based on the acceleration, and the movement speed of the laser emission module at each different moment is adjusted to the target speed corresponding to each different moment.

[0084] In this case, when the laser emission module reaches the position corresponding to the preset phase at the latest preset moment, the movement speed of the laser emission module can be the current movement speed obtained above, or can be other speeds except the current movement speed.

[0085] In one embodiment of the present invention, when adjusting the laser emitting module to a target speed, the speed difference between the current movement speed of the laser emitting module and the target speed may be calculated, and the movement speed of the laser emitting module may be adjusted based on the speed difference.

[0086] Among them, the movement speed of the laser emission module can be controlled by collecting the movement speed of the rotating parts through the control mechanism, and processing the information detected by the inertial measurement unit to obtain the target speed, which is then sent to the actuator. The actuator will act to speed up or slow down the movement speed of the current laser emission module.

[0087] It can be seen from the above that when the solution provided by the embodiment of the present invention is applied to calibrate the laser radar, by calculating the difference between the detected phase and the preset phase, as well as the time difference between the detection moment and the most recent preset moment, the target speed of the laser emission module can be accurately calculated based on the above difference and time difference. After adjusting the movement speed of the laser emission module to the target speed, the phase of the laser emission module at the most recent preset moment can be the preset phase, that is, the laser emission module can accurately pass through the position corresponding to the preset phase at the most recent preset moment, thereby realizing the laser radar calibration and improving the accuracy of the point cloud data collected by the laser radar.

[0088] In one embodiment of the present invention, the preset phase is zero phase. Figure 2 In addition to the implementation method provided in step S102A in the illustrated embodiment, the movement speed of the laser emission module can also be adjusted through the phase locking mechanism included in the laser radar, so that the phase of the laser emission module is zero phase at each preset moment.

[0089] Since the correspondence between the zero phase of the laser emission module and the position of the laser emission module is relatively accurate, the movement speed of the laser emission module is adjusted based on the detected phase, detection time and zero phase. This can ensure that when the phase of the laser emission module is the preset phase at each preset moment, the laser emission module accurately passes through the position corresponding to the zero phase, thereby improving the accuracy of the point cloud data collected by the lidar.

[0090] In one embodiment of the present invention, the above-mentioned laser radars are multiple laser radars in the same scene, and the multiple laser radars are timed by the same clock device.

[0091] In one embodiment of the present invention, the clock device is a GPS clock device.

[0092] By using GPS clock equipment, multiple lidars can be accurately timed to ensure that the clocks of multiple lidars are synchronized, which is conducive to data fusion between multiple radars.

[0093] In addition, the above-mentioned clock device may also be other clock devices, which is not limited in the embodiment of the present invention.

[0094] In roadside applications, multiple LiDARs are typically deployed at different locations to collect point cloud data from the same environment. The acquisition areas of these LiDARs can be the same, different, or even partially overlapping. After collecting point cloud data, the multiple LiDAR point cloud data can be fused to generate the fused point cloud data, which serves as the point cloud data for the entire environment.

[0095] For example, when using multiple laser radars to collect point cloud data of a road, multiple laser radars can be deployed on both sides of the road. Multiple laser radars collect point cloud data of the road from different collection angles. After the deployed multiple laser radars collect point cloud data, the point cloud data collected by the multiple laser radars are fused to obtain the point cloud data of the above-mentioned road.

[0096] However, due to reasons such as the accumulation of mechanical errors, the point cloud time in the overlapping areas of view of multiple lidars is prone to misalignment. Moreover, each time the data is fused, the time error of the laser emission components of the radar corresponding to the data frames from different radars is unpredictable, which leads to unstable perception results when road targets move at high speeds and the perception accuracy cannot be guaranteed.

[0097] To address this issue, in this embodiment, for each of the multiple laser radars, the same clock device can first be used to synchronize the laser radar with the laser. The phase of the laser emission module of the laser radar is then detected, and the detection time of the phase is obtained. Based on the detected phase, the detection time, and the preset phase, the movement speed of the laser emission module of the laser radar is adjusted. This operation is performed for each laser radar, so that the phase of the laser emission module of each laser radar is the corresponding preset phase at each identical preset time.

[0098] The acquisition cycles of the above-mentioned multiple laser radars may be the same or different. When setting the above-mentioned preset time, it can be set according to the acquisition cycle of each laser radar.

[0099] It can be seen from the above that when each laser radar is calibrated using the solution provided in the embodiment of the present invention, at each preset moment, the phase of the laser emission module of each laser radar is the corresponding preset phase, thereby enabling synchronous scanning of multiple laser radars. This avoids the asynchronous scanning of multiple laser radars due to different mechanical errors that may exist in different laser radars. By fusing the point cloud data collected by multiple laser radars that are scanned synchronously, more accurate fused point cloud data can be obtained.

[0100] In one embodiment of the present invention, see Figure 3, a flow chart of a third laser radar calibration method is provided. In this embodiment, there are multiple laser radars. After calibrating each of the multiple laser radars, the above method also includes the following steps S103-S105.

[0101] Step S103: Determine a first laser radar from multiple laser radars, and determine data collected by the first laser radar with a frame time of the first moment as first point cloud data.

[0102] Specifically, any one laser radar can be selected from the above-mentioned multiple laser radars as the first laser radar, and the first point cloud data can be determined in the point cloud data collected by the first laser radar, and the frame time of the first point cloud data is the first moment.

[0103] It is determined that the first point cloud data has the following two situations.

[0104] In the first case, each frame collected by the first laser radar can be determined as the first point cloud data.

[0105] In the second case, within the time period consisting of two adjacent preset moments (assuming it is t1-t2), the first lidar may operate for multiple scanning cycles. It is understandable that moment t1 has been calibrated, so the closer the frame moment is to t1, the higher the accuracy, and the closer it is to t2, the lower the accuracy. In this case, when determining the first point cloud data, based on each preset moment, the point cloud data with a frame moment later than the preset moment and a frame moment closer to the preset moment can be selected as the first point cloud data.

[0106] For example, if the acquisition period of the first laser radar is 100ms, and the above-mentioned preset time is an integer number of seconds after the laser radar starts working, when determining the first point cloud data, the point cloud data with a frame time of 10ms, 110ms, 210ms, etc., which is later than the preset time and close to the preset time, can be determined as the first point cloud data.

[0107] In one embodiment of the present invention, for each preset moment, point cloud data whose frame time is later than the preset moment and whose time difference with the preset moment is less than or equal to the preset time difference may be determined as the first point cloud data.

[0108] For example, the preset time difference may be 0.1 seconds, 0.2 seconds, 0.3 seconds, etc.

[0109] For example, if the acquisition period of the first laser radar is 100ms, the above-mentioned preset time is an integer number of seconds after the laser radar starts working, and the above-mentioned preset time difference is set to 200ms, then when determining the first point cloud data, the point cloud data with a frame time of n+0.1 seconds and the point cloud data with a frame time of n+0.2 seconds can be determined as the first point cloud data, where n is an integer number of seconds.

[0110] Step S104: Select the data collected by the remaining laser radars with the frame time being the second moment as the second point cloud data.

[0111] The time difference between the first moment and the second moment does not exceed the preset time difference.

[0112] The above-mentioned preset time difference can be set manually, taking into account the time differences of various lidars caused by the timing errors of the clock equipment and the errors in the data transmission process.

[0113] For example, the preset time difference may be 1 millisecond, 0.5 milliseconds or other durations.

[0114] Specifically, since the multiple laser radars being calibrated are scanned synchronously, the point cloud data collected by the multiple laser radars are also collected synchronously. Therefore, for each remaining laser radar except the first laser radar, the point cloud data collected by the remaining laser radar can be determined as the second point cloud data based on the first moment of the above-mentioned first point cloud data, in which the time difference between the frame moment and the first moment is less than the preset time difference.

[0115] For example, if there are two laser radars M and N to be calibrated, the scanning period of these two laser radars is 100 milliseconds, and the preset time set when calibrating these two laser radars is an integer number of seconds after the laser radars start working, then the correspondence between the frames used for data fusion of these two laser radars can be expressed by the following Table 1:

[0116] Table 1

[0117]

[0118] In Table 1 above, the above t is usually 100 ms, which is consistent with the acquisition period of the radar, and the above d represents the above preset time difference. For example, d can be set to 3 milliseconds.

[0119] Step S105: Fusing the first point cloud data and the second point cloud data.

[0120] Specifically, the first point cloud data can have multiple frames, and the second point cloud data can also have multiple frames. When performing point cloud fusion, for each frame of the first point cloud data, the second point cloud data that is closest to the first moment of the first point cloud data at the second moment can be determined from the multiple second point cloud data collected by each of the remaining lidars, and then the determined multiple frames of second point cloud data and the first point cloud data are fused to obtain fused point cloud data.

[0121] After the radar calibration, the above multiple laser radars are scanned synchronously (ie, when the phase of the laser emission module of radar A is When the phase of the laser emission module of radar B is To ensure a one-to-one correspondence between phases, when each set of data is fused, the problem of scanning time misalignment caused by radar phase differences between consecutive fused frames can be eliminated. Therefore, the lidar calibration solution provided by this method embodiment can improve the accuracy of the fused point cloud data, thereby improving the accuracy of monitoring the acquisition environment.

[0122] In the above embodiment, when there are multiple laser radars, each laser radar can be synchronized first, and then each laser radar can be calibrated to achieve synchronous scanning of multiple laser radars. In addition, the following can also be used Figure 4 In the illustrated embodiment, step S102B implements synchronous scanning of multiple laser radars.

[0123] In one embodiment of the present invention, see Figure 4 , a flowchart of a fourth laser radar calibration method is provided. In an embodiment of the present invention, there are multiple laser radars, including a reference radar and at least one third laser radar with the same acquisition period. The above step S102 can be implemented by the following step S102B:

[0124] Step S102B: According to the reference phase of the reference radar at the reference moment, the movement speed of the laser emission module of the third laser radar is adjusted so that the phase of the laser emission module of the third laser radar at the preset moment is the preset phase.

[0125] The reference time corresponds to the preset time, and the reference phase corresponds to the preset phase one by one.

[0126] The above-mentioned reference radar is used to calibrate the third laser radar. By adjusting the movement speed of the laser emission module of the third laser radar, the reference radar and the third laser radar maintain synchronous scanning.

[0127] The above-mentioned reference radar can be the laser radar with the highest acquisition accuracy among the above-mentioned multiple laser radars, or it can be any laser radar.

[0128] The above-mentioned reference radar and the third laser radar maintain synchronous scanning, which can be understood as when the phase of the laser emission module of the reference radar is the reference phase at the reference moment, the moment recorded by the clock of the third laser radar is the preset moment, and the phase of the laser emission module of the third laser radar is the preset phase.

[0129] Specifically, the corresponding relationship between the reference phase and the preset phase may be set first.

[0130] Among them, the reference time is recorded by the reference radar clock, and the preset time is recorded by the third laser radar clock. The reference time and the preset time correspond one to one. In theory, they can be the same time, and the difference between the two does not exceed 1 to 2ms. The error is caused by the GPS timing error and can be calibrated in advance.

[0131] During operation, assuming that the scanning period of the reference radar is 100ms, the reference moment can be set to 10 times the scanning period. For example, every 200s is the reference moment, and the corresponding preset moment can be 202ms, 402ms... Based on the phase of the current reference radar, its phase at each reference moment can be estimated and recorded as the reference phase. Then, based on the pre-calibrated relationship, the preset phase is determined. Then, based on the difference between the current moment and the preset moment, and the difference between the current phase and the preset phase of the third laser radar, the movement speed of the third laser radar is adjusted so that the third laser radar passes through the preset phase at the preset moment, thereby ensuring the scanning synchronization between the reference radar and the third laser radar.

[0132] The above embodiment does not calibrate the relationship between time and radar phase, but only adjusts the relative phase relationship between multiple radars.

[0133] Corresponding to the above-mentioned laser radar calibration method, an embodiment of the present invention also provides a laser radar calibration device.

[0134] In one embodiment of the present invention, see Figure 5 , provides a structural schematic diagram of a first laser radar calibration device, the device comprising:

[0135] The phase detection module 501 is used to detect the phase of the laser emission module of the laser radar and obtain the detection time of the phase;

[0136] The speed adjustment module 502 is used to adjust the movement speed of the laser emission module based on the detected phase and the detection time, so that the phase of the laser emission module is a preset phase at each preset time, wherein the preset time is set according to the acquisition cycle of the laser radar.

[0137] Since the error between the time required for the laser emission module to rotate one circle and the acquisition cycle of the laser radar is usually small, the smaller error has little impact on the point cloud data collected by the laser radar. However, during the operation of the laser radar, the above error will continue to accumulate as the working time of the laser radar increases, and eventually have a greater impact on the point cloud data collected by the laser radar, reducing the accuracy of the point cloud data collected by the laser radar. It can be seen from the above that when the scheme provided by the embodiment of the present invention is used to calibrate the laser radar, the preset moment is set according to the acquisition cycle of the laser radar, and the time difference between two adjacent preset moments is the duration corresponding to one or more acquisition cycles. The speed of the laser emission module is adjusted so that the phase of the laser emission module at each preset moment is the preset phase. It can be understood that the phase of the laser emission module is reset every one or more acquisition cycles, thereby avoiding the above error from accumulating as the working time of the laser radar increases, reducing the impact of the above error on the quality of the laser radar point cloud data, especially the impact on the accuracy of the point cloud data in the multi-sensor fusion scenario.

[0138] In one embodiment of the present invention, the speed adjustment module 502 is specifically configured to:

[0139] Based on the difference between the detected phase and the preset phase, and the time difference between the detection moment and the most recent preset moment, the target speed of the laser emission module is calculated, and the movement speed of the laser emission module is adjusted to the target speed, so that the phase of the laser emission module at each preset moment is the preset phase, wherein the most recent preset moment is a preset moment after the detection moment and adjacent to the detection moment.

[0140] It can be seen from the above that when the solution provided by the embodiment of the present invention is applied to calibrate the laser radar, by calculating the difference between the detected phase and the preset phase, as well as the time difference between the detection moment and the most recent preset moment, the target speed of the laser emission module can be accurately calculated based on the above difference and time difference. After adjusting the movement speed of the laser emission module to the target speed, the phase of the laser emission module at the most recent preset moment can be the preset phase, that is, the laser emission module can accurately pass through the position corresponding to the preset phase at the most recent preset moment, thereby realizing the laser radar calibration and improving the accuracy of the point cloud data collected by the laser radar.

[0141] In one embodiment of the present invention, the preset phase is a zero phase.

[0142] In this solution, the preset phase is zero phase. Because the correspondence between the laser emission module's zero phase and its position is relatively accurate, adjusting the laser emission module's speed based on the detected phase, detection moment, and zero phase ensures that the laser emission module's phase is the preset phase at each preset moment, thereby improving the accuracy of the point cloud data collected by the lidar.

[0143] In one embodiment of the present invention, the laser radars are multiple laser radars in the same scene, and the multiple laser radars are timed by the same clock device.

[0144] It can be seen from the above that when each laser radar is calibrated using the solution provided in the embodiment of the present invention, at each preset moment, the phase of the laser emission module of each laser radar is the corresponding preset phase, thereby enabling synchronous scanning of multiple laser radars. This avoids the asynchronous scanning of multiple laser radars due to different mechanical errors that may exist in different laser radars. By fusing the point cloud data collected by multiple laser radars that are scanned synchronously, more accurate fused point cloud data can be obtained.

[0145] In one embodiment of the present invention, the clock device is a GPS clock device.

[0146] In this solution, the GPS clock device is used to accurately provide time for multiple lidars, ensuring that the clocks of multiple lidars are synchronized, which is conducive to data fusion between multiple lidars.

[0147] In one embodiment of the present invention, see Figure 6 , provides a structural schematic diagram of a second laser radar calibration device. In this embodiment, the number of the laser radars is multiple, and the device further includes:

[0148] A first data acquisition module 503 is configured to determine a first laser radar from a plurality of laser radars, and determine data collected by the first laser radar with a first frame time as first point cloud data;

[0149] The second data acquisition module 504 is configured to select data collected by the remaining laser radars and having a frame time of the second moment as the second point cloud data; wherein the time difference between the first moment and the second moment does not exceed a preset time difference;

[0150] The data fusion module 505 is configured to fuse the first point cloud data with the second point cloud data.

[0151] As can be seen from the above, when the solution provided by the embodiment of the present invention is applied to calibrate the laser radar, after the radar is calibrated, the above-mentioned multiple laser radars are scanned synchronously (that is, when the phase of the laser emission module of radar A is When the phase of the laser emission module of radar B is To ensure a one-to-one correspondence between phases, when each set of data is fused, the problem of scanning time misalignment caused by radar phase differences between consecutive fused frames can be eliminated. Therefore, the lidar calibration solution provided by this method embodiment can improve the accuracy of the fused point cloud data.

[0152] In one embodiment of the present invention, the number of the laser radars is multiple, including a reference radar and at least one third laser radar, all of which have the same acquisition period;

[0153] The speed adjustment module 502 is specifically configured to:

[0154] According to the reference phase of the reference radar at the reference time, the movement speed of the laser emission module of the third laser radar is adjusted so that the phase of the laser emission module of the third laser radar at the preset time is the preset phase, wherein,

[0155] The reference time corresponds to the preset time;

[0156] The reference phase corresponds to the preset phase in a one-to-one manner.

[0157] As can be seen from the above, when the solution provided by the embodiment of the present invention is applied to calibrate the third laser radar, the movement speed of the laser emission module of the third laser radar is adjusted according to the reference phase of the reference radar at the reference moment, so that when the phase of the laser emission module of the reference radar at the reference moment is the reference phase, the moment recorded by the clock of the third laser radar is the preset moment, and the phase of the laser emission module of the third laser radar is the preset phase. Since the clock of the reference radar and the clock of the third laser radar are usually difficult to keep synchronized, the reference moment corresponds to the preset moment and can be regarded as the moment recorded by the clocks of the two laser radars for the same moment. Therefore, after adjusting the movement speed of the laser emission module of the third laser radar, at each reference moment or the actual moment represented by the preset moment corresponding to it, the phase of the laser emission module of the reference radar is the reference phase, and the phase of the laser emission module of the third laser radar is the preset phase, thereby achieving synchronous scanning of the reference radar and the third laser radar.

[0158] The embodiment of the present invention further provides an electronic device, such as Figure 7 As shown, it includes a processor 701, a communication interface 702, a memory 703 and a communication bus 704, wherein the processor 701, the communication interface 702, and the memory 703 communicate with each other through the communication bus 704.

[0159] Memory 703, used for storing computer programs;

[0160] The processor 701 is configured to execute the program stored in the memory 703, and implement the following steps:

[0161] Detecting the phase of a laser emission module of a laser radar and obtaining a detection time of detecting the phase;

[0162] Based on the detected phase and the detection moment, the movement speed of the laser emission module is adjusted so that the phase of the laser emission module is a preset phase at each preset moment, wherein the preset moment is set according to the acquisition cycle of the laser radar.

[0163] In addition, the above-mentioned electronic device can also implement other lidar calibration methods as described in the previous method embodiment part, which will not be described in detail here.

[0164] The communication bus mentioned in the electronic device mentioned above may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. This communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is used in the figure, but this does not mean that there is only one bus or only one type of bus.

[0165] The communication interface is used for communication between the above electronic device and other devices.

[0166] The memory may include random access memory (RAM) or non-volatile memory (NVM), such as at least one disk storage. Alternatively, the memory may be at least one storage device located away from the processor.

[0167] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, and discrete hardware components.

[0168] In another embodiment provided by the present invention, a computer-readable storage medium is also provided, which stores a computer program. When the computer program is executed by a processor, the steps of any of the above-mentioned lidar calibration methods are implemented.

[0169] In another embodiment provided by the present invention, a computer program product containing instructions is also provided, which, when executed on a computer, enables the computer to execute any of the laser radar calibration methods in the above embodiments.

[0170] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) method. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that includes one or more available media. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0171] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0172] Each embodiment in this specification is described in a related manner. Similar portions between embodiments can be referenced to each other. Each embodiment focuses on the differences between other embodiments. In particular, the device, electronic device, computer-readable storage medium, and computer program product embodiments are generally similar to the method embodiments, so their descriptions are relatively simple. For related portions, reference can be made to the descriptions of the method embodiments.

[0173] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A laser radar calibration method, characterized in that: The method comprises: Detecting the phase of a laser emission module of a laser radar and obtaining a detection time of the phase; the laser radars are multiple laser radars deployed at different locations; the multiple laser radars collect point cloud data of the environment from different collection angles; Based on the detected phase and the detection time, adjusting the movement speed of the laser emission module so that the phase of the laser emission module is a preset phase at each preset time, wherein the preset time is set according to the acquisition period of the laser radar; After adjusting the movement speed of the laser emission module based on the detected phase and the detection time, the method further includes: The point cloud data collected by the multiple laser radars are fused; the point cloud data involved in the fusion include: for each preset moment, the point cloud data whose frame time is later than the preset moment and the time difference between the frame time and the preset moment is not greater than the preset time difference.

2. The method according to claim 1, characterized in that The adjusting the movement speed of the laser emission module based on the detected phase and the detection time includes: Based on the difference between the detected phase and the preset phase, and the time difference between the detection moment and the most recent preset moment, the target speed of the laser emission module is calculated, and the movement speed of the laser emission module is adjusted to the target speed, wherein the most recent preset moment is a preset moment after the detection moment and adjacent to the detection moment.

3. The method according to claim 1 or 2, characterized in that The preset phase is a zero phase.

4. The method according to claim 1 or 2, characterized in that The multiple laser radars are timed by the same clock device.

5. The method according to claim 4, characterized in that The clock device is a GPS clock device.

6. The method according to claim 1, characterized in that The method further comprises: Determine a first laser radar from the multiple laser radars, and determine data collected by the first laser radar with a first frame time as first point cloud data; Selecting data collected by the remaining laser radars with a frame time of the second moment as the second point cloud data; wherein the time difference between the first moment and the second moment does not exceed the preset time difference; The first point cloud data and the second point cloud data are fused.

7. The method according to claim 1, characterized in that The laser radar includes a reference radar and at least one third laser radar having the same acquisition period. The adjusting of the movement speed of the laser emission module based on the detected phase and the detection time so that the phase of the laser emission module at each preset time is a preset phase includes: According to the reference phase of the reference radar at the reference time, the movement speed of the laser emission module of the third laser radar is adjusted so that the phase of the laser emission module of the third laser radar at the preset time is the preset phase, wherein, The reference time corresponds to the preset time; The reference phase corresponds to the preset phase in a one-to-one manner.

8. A laser radar calibration device, characterized in that: The device comprises: A phase detection module is used to detect the phase of the laser emission module of the laser radar and obtain a detection time of the phase; a speed adjustment module, configured to adjust the movement speed of the laser emission module based on the detected phase and the detection time, so that the phase of the laser emission module is a preset phase at each preset time, wherein the preset time is set according to the acquisition period of the laser radar; The laser radars are multiple laser radars deployed at different locations; the multiple laser radars collect point cloud data of the environment from different collection angles; The device further comprises: A fusion module is used to fuse the point cloud data collected by the multiple lidars after the speed adjustment module adjusts the movement speed of the laser emission module based on the detected phase and the detection moment; the point cloud data involved in the fusion include: for each preset moment, the point cloud data whose frame moment is later than the preset moment and the time difference between the frame moment and the preset moment is not greater than the preset time difference.

9. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; Memory for storing computer programs; A processor, configured to implement the method steps described in any one of claims 1 to 7 when executing a program stored in a memory.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method steps according to any one of claims 1 to 7 are implemented.

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