CN114740459A - Laser radar calibration method and device - Google Patents
Laser radar calibration method and device Download PDFInfo
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- CN114740459A CN114740459A CN202210421901.2A CN202210421901A CN114740459A CN 114740459 A CN114740459 A CN 114740459A CN 202210421901 A CN202210421901 A CN 202210421901A CN 114740459 A CN114740459 A CN 114740459A
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Abstract
The embodiment of the invention provides a laser radar calibration method and a laser radar calibration device, which relate to the technical field of laser scanning, and the method comprises the following steps: detecting the phase of a laser emission module of a laser radar, and obtaining the detection time of 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. By applying the laser radar calibration scheme provided by the embodiment of the invention, the accuracy of fusing point cloud data acquired by multiple laser radars can be improved.
Description
Technical Field
The invention relates to the technical field of laser scanning, in particular to a laser radar calibration method and device.
Background
Including the laser emission module among the mechanical rotation type laser radar, the laser emission module is used for to external transmission laser to and receive the laser that the external world reflected, and in mechanical rotation type laser radar working process, the laser emission module rotates around the rotation axis, and laser radar generates a frame point cloud data based on the information of the laser of receiving in an acquisition cycle.
Because there are mechanical errors between each part that mechanical rotation type lidar includes, bring great influence for subsequent multisensor data fusion's accuracy, consequently need calibrate lidar.
Disclosure of Invention
The embodiment of the invention aims to provide a laser radar calibration method and device to improve the accuracy of point cloud data fusion acquired by multiple laser radars. The specific technical scheme is as follows:
in a first aspect, an embodiment of the present invention provides a laser radar calibration method, where the method includes:
detecting the phase of a laser emission module of a laser radar, and acquiring the detection time of 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, wherein the preset time is set according to the acquisition period of the laser radar.
In an embodiment of the present invention, the adjusting the movement speed of the laser emission module based on the detected phase and the detection time includes:
calculating the target speed of the laser emission module according to the difference between the detected phase and a preset phase and the time difference between the detection time and the latest preset time, and adjusting the movement speed of the laser emission module to be the target speed, wherein the latest preset time is the preset time which is adjacent to the detection time after the detection time.
In one embodiment of the present invention, the predetermined phase is a zero phase.
In an embodiment of the present invention, the lidar is a plurality of lidars in the same scene, and the lidars are timed by the same clock device.
In one embodiment of the present invention, the clock device is a GPS clock device.
In an embodiment of the present invention, the number of the laser radars is plural, and the method further includes:
determining a first laser radar from the plurality of laser radars, and determining data which are acquired by the first laser radar and have a frame time as a first moment as first point cloud data;
selecting data which are acquired by the other laser radars and have a frame time as a second time as second point cloud data; wherein the time difference between the first time and the second time is not more than a preset time difference;
and fusing the first point cloud data and the second point cloud data.
In an embodiment of the present invention, the plurality of laser radars include a reference radar and at least one third laser radar having the same acquisition period, and the adjusting the movement speed of the laser emission module based on the detected phase and the detection time to make the phase of the laser emission module at each preset time be a preset phase includes:
adjusting the movement speed of the laser emission module of the third laser radar according to the reference phase of the reference radar at the reference moment, so that the phase of the laser emission module of the third laser radar is the preset phase at the preset moment, wherein,
the reference time corresponds to the preset time;
the reference phases correspond to the preset phases one to one.
In a second aspect, an embodiment of the present invention further provides a laser radar calibration apparatus, where the apparatus includes:
the phase detection module is used for detecting the phase of a laser emission module of the laser radar and obtaining the detection time for detecting the phase;
and the speed adjusting module is used for 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, wherein the preset time is set according to the acquisition period of the laser radar.
In an embodiment of the present invention, the speed adjustment module is specifically configured to:
calculating a target speed of the laser emission module according to a difference between the detected phase and a preset phase and a time difference between the detection time and a latest preset time, and adjusting a movement speed of the laser emission module to the target speed so that the phase of the laser emission module is a preset phase at each preset time, wherein the latest preset time is a preset time which is adjacent to the detection time after the detection time.
In one embodiment of the present invention, the predetermined phase is a zero phase.
In an embodiment of the present invention, the lidar is a plurality of lidars in the same scene, and the lidars are timed by the same clock device.
In one embodiment of the present invention, the clock device is a GPS clock device.
In an embodiment of the present invention, the number of the laser radars is plural, and the apparatus further includes:
the first data acquisition module is used for determining a first laser radar from the plurality of laser radars and determining data which are acquired by the first laser radar and have a frame time as a first moment as first point cloud data;
the second data acquisition module is used for selecting data which are acquired by the other laser radars and have the frame time as the second point cloud data; wherein the time difference between the first time and the second time is not more than a preset time difference;
and the data fusion module is used for fusing the first point cloud data and the second point cloud data.
In one embodiment of the invention, the number of the laser radars is multiple, and the laser radars comprise a reference radar and at least one third laser radar with the same acquisition period;
the speed adjustment module is specifically configured to:
adjusting the movement speed of the laser emission module of the third laser radar according to the reference phase of the reference radar at the reference moment, so that the phase of the laser emission module of the third laser radar is the preset phase at the preset moment, wherein,
the reference time corresponds to the preset time;
the reference phases correspond to the preset phases one to one.
In a third aspect, an embodiment of the present invention further provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, where the processor, the communication interface, and the memory complete mutual communication through the communication bus;
a memory for storing a computer program;
a processor, configured to implement the steps of the laser radar calibration method according to any one of the first aspect described above when executing a program stored in the memory.
In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium, where 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 according to any of the first aspects are implemented.
The embodiment of the invention has the following beneficial effects:
according to the above, when the laser radar is calibrated by applying the scheme provided by the embodiment of the invention, the preset time is set according to the acquisition period of the laser radar, the time difference between two adjacent preset times is the time length corresponding to one or more acquisition periods, and the speed of the laser emission module is adjusted so that the phase of the laser emission module at each preset time is the preset phase, which can be understood as resetting the phase of the laser emission module at every one or more acquisition periods, therefore, the error is prevented from being accumulated continuously along with the increase of the working time of the laser radar, and the influence of the error on the point cloud data quality of the laser radar, particularly the point cloud data accuracy under the multi-sensor fusion scene, is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other embodiments can be obtained by referring to these drawings.
Fig. 1 is a schematic flowchart of a first lidar calibration method according to an embodiment of the present invention;
fig. 2 is a schematic flowchart of a second laser radar calibration method according to an embodiment of the present invention;
FIG. 3 is a schematic flowchart of a third laser radar calibration method according to an embodiment of the present invention;
fig. 4 is a schematic flowchart of a fourth laser radar calibration method according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a first lidar calibration apparatus according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a second lidar calibration apparatus according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention are within the scope of the present invention.
Referring to fig. 1, fig. 1 is a schematic flow chart of a first lidar calibration method according to an embodiment of the present invention, where the method includes the following steps S101-S102.
Step S101: and detecting the phase of a laser emission module of the laser radar and obtaining the detection time of the detected phase.
The phase place of laser radar transmission module can be defined as the rotation angle of laser radar transmission module for initial zero phase position, and the position of laser module can mark in advance or begin the during operation with the radar is zero phase.
In an embodiment of the present invention, the laser radar may include a measurement module for detecting a phase of the laser emission module, and when the laser emission module emits laser to the outside, the measurement module may be used to detect the laser emission module, so as to obtain the phase. And recording the detection time of the measurement module as the detection time. The detection may be performed in real time or at fixed time intervals.
In an embodiment of the invention, the measurement module is an inertial measurement unit.
In addition, besides the phase of the laser emission module is detected by the measuring module, the phase of the laser emission module can be detected by the existing phase measuring technology, and the detailed description is omitted here.
Step S102: 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.
And the preset time is set according to the acquisition period of the laser radar.
The preset time may be preset, and the timing start point may be a time at which the laser radar starts to operate.
For example, the preset time may be set to 1 second or 2 seconds after the laser radar starts operating.
In one embodiment of the present invention, a preset time may be set every one or more acquisition cycles.
For example, if the acquisition period is 100 milliseconds, a preset time may be set every 10 acquisition periods, and the preset time is an integer second such as 1 second and 2 seconds, and the time difference between every two adjacent preset times is the same.
In addition, the time difference between two adjacent preset times can also be different.
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 period.
The preset phase may be any phase that is preset. The preset phase can be set to be zero,
Phase, etc.
The movement speed of the laser emission module can be the angular speed of the laser emission module rotating around the shaft or the linear speed of the laser emission module.
Specifically, the preset phase may be predetermined, and after the detected phase and the detection time are obtained, the movement speed of the laser emitting module is adjusted based on the detected phase, the detection time, and the determined phase.
The specific implementation manner of adjusting the moving speed of the laser emitting module based on the detected phase and the detected time can be seen in the following embodiments, which will not be described in detail here.
According to the above, when the laser radar is calibrated by applying the scheme provided by the embodiment of the invention, the preset time is set according to the acquisition period of the laser radar, the time difference between two adjacent preset times is the time length corresponding to one or more acquisition periods, and the speed of the laser emission module is adjusted so that the phase of the laser emission module at each preset time is the preset phase, which can be understood as resetting the phase of the laser emission module at every one or more acquisition periods, therefore, the error is prevented from being accumulated continuously along with the increase of the working time of the laser radar, and the influence of the error on the point cloud data quality of the laser radar, particularly the point cloud data accuracy under the multi-sensor fusion scene, is reduced.
In an embodiment of the present invention, referring to fig. 2, a flowchart of a second laser radar calibration method is provided, and in this embodiment, the step S102 may be implemented by the following step S102A.
Step S102A: and calculating the target speed of the laser emission module according to the difference between the detected phase and the preset phase and the time difference between the detection moment and the latest preset moment, and adjusting the movement speed of the laser emission module to be the target speed so that the phase of the laser emission module at each preset moment is the preset phase.
And the latest preset moment is a preset moment which is adjacent to the detection moment after the detection moment.
For example, the preset time may be set to be an integer number of seconds such as 1 second or 2 seconds, and in this case, if the detection time is 0.9 second, the latest preset time is 1 second which is after 0.9 second and adjacent to 0.9 second among the respective preset times; if the detection time is 1.1 second, the latest preset time is 2 seconds that are 1.1 seconds later and adjacent to 1.1 seconds among the preset times.
Specifically, the difference between the detected phase and the preset phase and the time difference between the detection time and the latest preset time can be calculated, the target speed of the laser emission module is calculated based on the calculated difference of the phases and the time difference, and then the movement speed of the laser emission module is adjusted to the calculated target speed.
In an 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 subtracted calculation result, which is used as the difference between the detected phase and the preset phase.
In addition, the difference between the detected phase and the preset phase may also be calculated using an inertial measurement mechanism in the laser radar.
When calculating the time difference, the detection time may be subtracted from the latest preset time, and the calculation result is the time difference between the detection time and the latest preset time.
In an embodiment of the present invention, after obtaining the difference and the time difference, the difference may be converted into a position difference between a current phase and a preset phase of the laser emitting module, the position difference is divided by the time difference, a result of the division is a target speed of the laser emitting module, and a moving speed of the laser emitting module is adjusted to the target speed.
If the position difference is represented by the arc, the calculated target speed is the target linear speed of the laser emission module, and the adjusted movement speed is the linear speed of the laser emission module; if the position difference is represented by an 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.
In this case, when the laser emission module reaches the preset phase at the latest preset time, the movement speed of the laser emission module is the calculated target speed.
In another embodiment of the present invention, the current movement speed of the laser emission module may be obtained, the acceleration of the laser emission module may be calculated according to the obtained current movement speed, the difference and the time difference, the target speeds at different times may be calculated according to the acceleration, and the movement speed of the laser emission module may be adjusted to the target speed corresponding to each different time at each different time.
In this case, when the laser emission module reaches the position corresponding to the preset phase at the latest preset time, the movement speed of the laser emission module may be the obtained current movement speed, or may be another speed other than the current movement speed.
In an embodiment of the present invention, when the laser emission module is adjusted to the target speed, a speed difference between the current movement speed of the laser emission module and the target speed may be calculated, and the movement speed of the laser emission module may be adjusted based on the speed difference.
The movement speed of the laser emission module can be controlled to acquire the movement speed of the rotating part through the control mechanism, information detected by the inertia measurement unit is processed to obtain a target speed, and the target speed is sent to the execution mechanism, and the movement speed of the current laser emission module is accelerated or slowed down through the action of the execution mechanism.
As can be seen from the above, when the laser radar is calibrated by applying the scheme provided by the embodiment of the present invention, by calculating the difference between the detected phase and the preset phase and the time difference between the detection time and the latest preset time, the target speed of the laser emission module can be accurately calculated according to the difference and the time difference, and after the movement speed of the laser emission module is adjusted to the target speed, the phase of the laser emission module at the latest preset time can be the preset phase, that is, the laser emission module can accurately pass through the position corresponding to the preset phase at the latest preset time, so that the laser radar calibration is realized, and the accuracy of the point cloud data acquired by the laser radar is improved.
In an embodiment of the invention, the predetermined phase is a zero phase. When the movement speed of the laser emission module is adjusted, in addition to the manner provided by step S102A in the embodiment shown in fig. 2, the movement speed of the laser emission module may be adjusted through a phase locking mechanism included in the laser radar, so that the phase of the laser emission module is zero at each preset time.
Because the zero phase of laser emission module and the corresponding relation between the position of laser emission module are comparatively accurate, consequently, based on the phase place that detects, detect constantly and zero phase place, adjust the velocity of motion of laser emission module, can make when the phase place of laser emission module is for predetermineeing the phase place under each predetermines constantly, the accurate position that corresponds through zero phase place of laser emission module to improve the accuracy of the point cloud data of laser radar collection.
In an embodiment of the present invention, the lidar is a plurality of lidar in the same scene, and the plurality of lidar is timed by the same clock device.
In an embodiment of the present invention, the clock device is a GPS clock device.
Utilize GPS clock equipment, can carry out accurate time service to a plurality of laser radar, guarantee that a plurality of laser radar clocks are synchronous to be favorable to the data fusion between a plurality of radars.
The clock device may be another clock device, which is not limited in the embodiment of the present invention.
In a road end application scenario, a plurality of laser radars are usually deployed at different positions, the plurality of laser radars acquire point cloud data of the same acquisition environment, and acquisition areas of different laser radars may be the same or different or partially overlapped. After the plurality of laser radars collect the point cloud data, the plurality of point cloud data collected by the plurality of laser radars can be fused to obtain fused point cloud data which is used as the point cloud data of the whole collection environment.
For example, when a plurality of laser radars are used to collect point cloud data of a road, the plurality of laser radars may be respectively deployed on two sides of the road, the plurality of laser radars collect the point cloud data of the road from different collection angles, and after the deployed plurality of laser radars collect the point cloud data, the point cloud data collected by the plurality of laser radars are fused to obtain the point cloud data of the road.
However, due to reasons such as accumulation of mechanical errors, the point cloud time of the overlapping area of the fields of view of multiple lidar is prone to be misaligned, and the time error of misalignment of laser emitting components of radars corresponding to data frames from different radars is unpredictable every time data are fused, so that the sensing result is unstable when the road target moves at a high speed, and the sensing precision cannot be guaranteed.
In order to solve this problem, in this embodiment, for each of the plurality of lidar, the same clock device may first time the lidar, then detect a phase of a laser emitting module of the lidar, obtain a detection time of the detected phase, and adjust a movement speed of the laser emitting module of the lidar based on the detected phase, the detection time, and a preset phase. And performing the operation on each laser radar, so that the phase of the laser emission module of each laser radar is the corresponding preset phase at each same preset time.
The acquisition periods of the plurality of laser radars may be the same or different. When the preset time is set, the preset time can be set according to the acquisition period of each laser radar.
As can be seen from the above, when each lidar is calibrated by applying the scheme provided by the embodiment of the present invention, at each preset time, the phases of the laser emission modules of each lidar are the respective corresponding preset phases, so that the synchronous scanning of a plurality of lidars can be realized, thereby avoiding the asynchronism of scanning of a plurality of lidars due to different mechanical errors possibly existing in different lidars, fusing the point cloud data acquired by a plurality of lidars which are synchronously scanned, and obtaining more accurate fused point cloud data.
In an embodiment of the present invention, referring to fig. 3, a flow chart of a third lidar calibration method is provided, in which in this embodiment, the number of the lidar is multiple, and after each of the plurality of the lidar is calibrated, the method further includes the following steps S103 to S105.
Step S103: and determining a first laser radar from the plurality of laser radars, and determining data which are acquired by the first laser radar and have the frame time as the first point cloud data.
Specifically, one of the plurality of laser radars may be selected as a first laser radar, and first point cloud data is determined from point cloud data collected by the first laser radar, where a frame time of the first point cloud data is a first time.
Determining the first point cloud data has the following two cases.
In the first case, each frame of the first lidar acquisition may be determined as the first point cloud data.
In the second case, the first lidar may be operated for a number of scanning cycles during a time period (assumed to be t 1-t 2) consisting of two adjacent preset times, it being understood that the time t1 has been corrected, so that the closer the frame time is to t1, the higher the accuracy, and the closer to t2, the lower the accuracy is. In this case, when determining the first point cloud data, point cloud data having a frame time later than the preset time and a frame time closer to the preset time may be selected as the first point cloud data based on each preset time.
For example, if the acquisition cycle of the first lidar is 100ms and the preset time is an integer of seconds after the lidar starts to operate, when determining the first point cloud data, point cloud data having frame times of 10ms, 110ms, 210ms, etc. later than the preset time and close to the preset time may be determined as the first point cloud data.
In an embodiment of the present invention, for each preset time, the point cloud data of which the frame time is later than the preset time and the time difference with the preset time is less than or equal to a preset time difference may be determined as the first point cloud data.
For example, the preset time difference may be 0.1 second, 0.2 second, 0.3 second, or the like.
For example, if the acquisition cycle of the first lidar is 100ms, the preset time is an integer number of seconds after the lidar starts to operate, and the preset time difference is set to 200ms, when determining the first point cloud data, point cloud data with a frame time of n +0.1 seconds and point cloud data with a frame time of n +0.2 seconds may be determined as the first point cloud data, where n is an integer number of seconds.
Step S104: and selecting data which are acquired by the other laser radars and have the frame time as the second time as second point cloud data.
Wherein the time difference between the first time and the second time does not exceed the preset time difference.
The preset time difference can be set artificially, and the time difference of each laser radar caused by the time service error of the clock equipment and the error in the data transmission process is considered.
For example, the preset time difference may be 1 millisecond, 0.5 millisecond, or other time duration.
Specifically, since the plurality of laser radars to be calibrated are scanned synchronously and the plurality of laser radar collected point cloud data are also synchronized, for each of the remaining laser radars except the first laser radar, point cloud data in which the time difference between the frame time and the first time is smaller than the preset time difference can be determined as second point cloud data in the point cloud data collected by the remaining laser radars according to the first time of the first point cloud data.
For example, if there are two lidar M, N performing calibration, the scanning periods of the two lidar are both 100ms, and the preset time set when the two lidar are calibrated is an integer seconds after the lidar starts to operate, the correspondence between the frames of the two lidar for data fusion can be represented by the following table 1:
TABLE 1
In table 1 above, t is typically 100ms, which is consistent with the radar acquisition period, and d represents the preset time difference, and may be set to 3 ms, for example.
Step S105: and fusing the first point cloud data and the second point cloud data.
Specifically, the first point cloud data may be multiframes, the second point cloud data may also be multiframes, and when point cloud fusion is performed, for each frame of the first point cloud data, the second point cloud data whose second time is closest to the first time of the first point cloud data may be determined in a plurality of second point cloud data acquired by each of the remaining laser radars, and then the determined multiframe second point cloud data and the first point cloud data are fused to obtain fused point cloud data.
After radar calibration, the plurality of lidar are synchronously scanned (i.e., when the phase of the laser emitting module of radar A is
When the phase of the laser emitting module of the radar B is
One-to-one correspondence of phases is guaranteed), and at this time, when data of each group are fused again, the problem of scanning time misalignment caused by radar phase difference among a plurality of continuous fusion frames can be eliminated. Therefore, the laser radar calibration scheme provided by the embodiment of the method can improve the accuracy of the fused point cloud data, and further improve the accuracy of monitoring the acquisition environment.
In the above embodiment, when there are multiple lidar, the timing of each lidar may be unified first, and then each lidar is calibrated, so as to implement synchronous scanning of multiple lidar. In addition, synchronous scanning of multiple lidar units may also be achieved through step S102B in the embodiment shown in fig. 4 below.
In an embodiment of the present invention, referring to fig. 4, a flowchart of a fourth lidar calibration method is provided, in an embodiment of the present invention, the number of the lidar is multiple, and the lidar includes a reference radar and at least one third lidar, where the acquisition cycles of the reference radar and the at least one third lidar are the same, and the step S102 may be implemented by the following step S102B:
step S102B: and adjusting the movement speed of the third laser radar laser emission module according to the reference phase of the reference radar at the reference moment, so that the phase of the third laser radar laser emission module is a preset phase at a preset time.
The reference time corresponds to the preset time, and the reference phases correspond to the preset phases one to one.
The reference radar is used for calibrating the third laser radar, and the reference radar and the third laser radar keep synchronous scanning by adjusting the movement speed of the laser emission module of the third laser radar.
The reference radar may be a laser radar having the highest acquisition accuracy among the plurality of laser radars, or may be any one of the laser radars.
The reference radar and the third laser radar keep synchronous scanning, and when the phase of the laser emission module of the reference radar is the reference phase at the reference time, the time recorded by the clock of the third laser radar is the preset time, and the phase of the laser emission module of the third laser radar is the preset phase.
Specifically, the correspondence between the reference phase and the preset phase may be set first.
The reference time is recorded by a reference radar clock, the preset time is recorded by a third laser radar clock, the reference time and the preset time are in one-to-one correspondence, theoretically, the reference time and the preset time can be the same time, the difference between the reference time and the preset time is not more than 1-2 ms, the error is caused by GPS time service error, and the GPS time service error can be calibrated in advance.
In the working process, assuming that the scanning period of the reference radar is 100ms, the reference time may be set to be 10 times of the scanning period, for example, every 200s is the reference time, the corresponding preset time may be 202ms, 402ms..
The above-described embodiment does not calibrate the relationship between the time and the radar phase, but only adapts the relative phase relationship between multiple radars.
Corresponding to the laser radar calibration method, the embodiment of the invention also provides a laser radar calibration device.
In one embodiment of the present invention, referring to fig. 5, there is provided a schematic structural diagram of a first lidar calibration apparatus, including:
the phase detection module 501 is configured to detect a phase of a laser emission module of a laser radar, and obtain a detection time for detecting the phase;
a speed adjusting module 502, configured to adjust a moving 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, where the preset time is set according to an acquisition cycle of the laser radar.
According to the above, when the laser radar is calibrated by applying the scheme provided by the embodiment of the invention, the preset time is set according to the acquisition period of the laser radar, the time difference between two adjacent preset times is the time length corresponding to one or more acquisition periods, and the speed of the laser emission module is adjusted so that the phase of the laser emission module at each preset time is the preset phase, which can be understood as resetting the phase of the laser emission module at every one or more acquisition periods, therefore, the error is prevented from being accumulated continuously along with the increase of the working time of the laser radar, and the influence of the error on the point cloud data quality of the laser radar, particularly the point cloud data accuracy under the multi-sensor fusion scene, is reduced.
In an embodiment of the present invention, the speed adjusting module 502 is specifically configured to:
calculating a target speed of the laser emission module according to a difference between the detected phase and a preset phase and a time difference between the detection time and a latest preset time, and adjusting a movement speed of the laser emission module to the target speed so that the phase of the laser emission module is a preset phase at each preset time, wherein the latest preset time is a preset time which is adjacent to the detection time after the detection time.
As can be seen from the above, when the laser radar is calibrated by applying the scheme provided by the embodiment of the present invention, by calculating the difference between the detected phase and the preset phase and the time difference between the detection time and the latest preset time, the target speed of the laser emission module can be accurately calculated according to the difference and the time difference, and after the movement speed of the laser emission module is adjusted to the target speed, the phase of the laser emission module at the latest preset time can be the preset phase, that is, the laser emission module can accurately pass through the position corresponding to the preset phase at the latest preset time, so that the laser radar calibration is realized, and the accuracy of the point cloud data acquired by the laser radar is improved.
In an embodiment of the present invention, the predetermined phase is a zero phase.
In this embodiment, the predetermined phase is a zero phase. Because the zero phase place of laser emission module and the corresponding relation between the position of laser emission module are comparatively accurate, consequently, based on the phase place that detects, detect constantly and zero phase place, adjust the velocity of motion of laser emission module, can make the phase place of laser emission module for predetermineeing the phase place under every predetermineeing constantly to improve the accuracy of the some cloud data of laser radar collection.
In an embodiment of the present invention, the lidar is a plurality of lidars in the same scene, and the lidars are timed by the same clock device.
As can be seen from the above, when each lidar is calibrated by applying the scheme provided by the embodiment of the present invention, at each preset time, the phases of the laser emission modules of each lidar are the respective corresponding preset phases, so that the synchronous scanning of a plurality of lidars can be realized, thereby avoiding the asynchronism of scanning of a plurality of lidars due to different mechanical errors possibly existing in different lidars, fusing the point cloud data acquired by a plurality of lidars which are synchronously scanned, and obtaining more accurate fused point cloud data.
In one embodiment of the present invention, the clock device is a GPS clock device.
In this scheme, utilize GPS clock equipment, can carry out accurate time service to a plurality of laser radar, guarantee that a plurality of laser radar clocks are synchronous to be favorable to the data fusion between a plurality of radars.
In an embodiment of the present invention, referring to fig. 6, a schematic structural diagram of a second lidar calibration apparatus is provided, in this embodiment, the number of the lidar is multiple, and the apparatus further includes:
a first data obtaining module 503, configured to determine a first laser radar from the multiple laser radars, and determine data, which is acquired by the first laser radar and whose frame time is a first time, as first point cloud data;
a second data obtaining module 504, configured to select, as second point cloud data, data that is acquired by the other laser radars and whose frame time is a second time; wherein the time difference between the first time and the second time is not more than a preset time difference;
and a data fusion module 505, configured to fuse the first point cloud data and the second point cloud data.
As can be seen from the above, when the lidar is calibrated by using the scheme provided in the embodiment of the present invention, after the lidar calibration, the plurality of lidar scanning units are synchronously scanned (i.e. when the phase of the laser emitting module of the radar a is equal to
When the phase of the laser emission module of the radar B is determined as
One-to-one correspondence of phases is guaranteed), and at this time, when data of each group are fused again, the problem of scanning time misalignment caused by radar phase difference among a plurality of continuous fusion frames can be eliminated. Therefore, the laser radar calibration scheme provided by the embodiment of the method can improve the accuracy of the fused point cloud data.
In one embodiment of the invention, the number of the laser radars is multiple, and the laser radars comprise a reference radar and at least one third laser radar with the same acquisition period;
the speed adjustment module 502 is specifically configured to:
adjusting the movement speed of the laser emission module of the third laser radar according to the reference phase of the reference radar at the reference moment, so that the phase of the laser emission module of the third laser radar is the preset phase at the preset moment, wherein,
the reference time corresponds to the preset time;
the reference phases correspond to the preset phases one to one.
As can be seen from the above, when the third laser radar is calibrated by applying the scheme provided in the embodiment of the present invention, 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 time, so that when the phase of the laser emission module of the reference radar is the reference phase at the reference time, the time recorded by the clock of the third laser radar is the preset time, and the phase of the laser emission module of the third laser radar is the preset phase. Because the clock of reference radar and the clock of third laser radar are difficult to keep synchronous usually, the reference moment is corresponding with the preset moment, can regard as the moment that the clock of these two kinds of laser radar is to same moment record, therefore, after the velocity of motion of adjustment third laser radar laser emission module, under the actual moment that every reference moment or its corresponding preset moment represented, the phase place of reference radar laser emission module is the reference phase place, the phase place of third laser radar laser emission module is for predetermineeing the phase place, thereby realize reference radar and third laser radar synchronous scanning.
An embodiment of the present invention further provides an electronic device, as shown in fig. 7, including a processor 701, a communication interface 702, a memory 703 and a communication bus 704, where the processor 701, the communication interface 702, and the memory 703 complete mutual communication through the communication bus 704,
a memory 703 for storing a computer program;
the processor 701 is configured to implement the following steps when executing the program stored in the memory 703:
detecting the phase of a laser emission module of a laser radar, and obtaining the detection time of 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, wherein the preset time is set according to the acquisition period of the laser radar.
Besides, the electronic device may also implement other lidar calibration methods as described in the previous embodiments, and will not be described in detail here.
The communication bus mentioned in the electronic device may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The communication bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown, but this does not mean that there is only one bus or one type of bus.
The communication interface is used for communication between the electronic equipment and other equipment.
The Memory may include a Random Access Memory (RAM) or a Non-Volatile Memory (NVM), such as at least one disk Memory. Alternatively, the memory may be at least one memory device located remotely from the processor.
The Processor may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; but also Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components.
In a further embodiment of the present invention, a computer-readable storage medium is further provided, in which a computer program is stored, and the computer program, when executed by a processor, implements the steps of any of the laser radar calibration methods described above.
In a further embodiment provided by the present invention, there is also provided a computer program product containing instructions which, when run on a computer, cause the computer to perform any of the lidar calibration methods of the embodiments described above.
In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to be performed in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). 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, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus, the electronic device, the computer-readable storage medium, and the computer program product embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiments.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. A method of lidar calibration, the method comprising:
detecting the phase of a laser emission module of a laser radar, and obtaining the detection time of 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, wherein the preset time is set according to the acquisition period of the laser radar.
2. The method of claim 1, wherein the adjusting the movement speed of the laser emitting module based on the detected phase and the detection time comprises:
calculating the target speed of the laser emission module according to the difference between the detected phase and a preset phase and the time difference between the detection time and the latest preset time, and adjusting the movement speed of the laser emission module to be the target speed, wherein the latest preset time is the preset time which is adjacent to the detection time after the detection time.
3. The method according to claim 1 or 2, wherein the predetermined phase is a zero phase.
4. The method according to claim 1 or 2, wherein the lidar is a plurality of lidar in the same scene, and the plurality of lidar are timed by the same clock device.
5. The method of claim 4, wherein the clock device is a GPS clock device.
6. The method of claim 1, wherein the lidar is plural in number, the method further comprising:
determining a first laser radar from the plurality of laser radars, and determining data which are acquired by the first laser radar and of which the frame time is the first time as first point cloud data;
selecting data which are collected by the other laser radars and have the frame time as the second time as second point cloud data; wherein the time difference between the first time and the second time is not more than a preset time difference;
and fusing the first point cloud data and the second point cloud data.
7. The method according to claim 1, wherein the number of the lidar is plural, the number of the lidar includes a reference radar and at least one third lidar, the acquisition periods of the reference radar and the at least one third lidar are the same, and the 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 at each preset time is a preset phase includes:
adjusting the movement speed of the laser emission module of the third laser radar according to the reference phase of the reference radar at the reference moment so as to enable the phase of the laser emission module of the third laser radar to be the preset phase at the preset moment, wherein,
the reference time corresponds to the preset time;
the reference phases correspond to the preset phases one to one.
8. A lidar calibration apparatus, the apparatus comprising:
the phase detection module is used for detecting the phase of a laser emission module of the laser radar and obtaining the detection time for detecting the phase;
and the speed adjusting module is used for 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, wherein the preset time is set according to the acquisition period of the laser radar.
9. An electronic device is characterized by comprising a processor, a communication interface, a memory and a communication bus, wherein the processor and the communication interface are used for realizing mutual communication by the memory through the communication bus;
a memory for storing a computer program;
a processor for implementing the method steps of any of claims 1 to 7 when executing a program stored in the memory.
10. A computer-readable storage medium, characterized in that a computer program is stored in the computer-readable storage medium, which computer program, when being executed by a processor, carries out the method steps of any one of the claims 1-7.
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| CN115598625B (en) * | 2022-11-07 | 2023-03-10 | 深圳煜炜光学科技有限公司 | Laser radar measurement correction method, device, equipment and storage medium |
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