A method, device and system for measuring timing clock synchronization error

Abstract

The present application belongs to the field of measurement technology, and discloses a method, device and system for measuring the synchronization error of a timing clock. The method comprises: obtaining point cloud data collected by the laser radar during the reciprocating swing of the laser radar, and recording each time when the photoelectric sensor is irradiated by the laser radar, and comparing the timing time data of the GNSS receiver to obtain a first time series; determining a target cloud point corresponding to a light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the GNSS receiver under test; calculating the timing clock synchronization error between the laser radar and the GNSS receiver under test according to the time difference between each time data of the first time series and the second time series; thereby being able to simply and conveniently measure the timing clock synchronization error between the laser radar and the GNSS receiver.

Description

Technical Field

[0001] The present application relates to the field of measurement technology, and in particular to a method, device and system for measuring a timing clock synchronization error. Background Art

[0002] At present, laser radars integrated with navigation positioning and orientation systems (POS) are widely used, and such laser radars are often used for surveying and mapping in the field of aerial surveying and mapping. When such laser radars are used, they usually obtain position data as initial values ​​through the global navigation satellite system (GNSS), and use the inertial navigation system (IMU) to obtain attitude change increments for solving the laser radar point cloud data collected synchronously.

[0003] In the field of aerial surveying and mapping, the time accuracy of laser radar point cloud data acquisition is extremely high, and the synchronization error between the laser radar and GNSS timing clock needs to be controlled within an extremely low range to ensure the reliability of the laser radar point cloud data. Therefore, measuring the synchronization error between the laser radar and GNSS timing clock is of great significance to whether the point cloud data can guarantee the accuracy of the solved data. At present, the measurement of the synchronization error between the laser radar and GNSS timing clock is usually carried out by the manufacturer using special equipment before the equipment leaves the factory. After leaving the factory, it is difficult for users to measure it by themselves. Therefore, it is usually difficult for users to know whether the synchronization error between the laser radar and GNSS timing clock has changed after leaving the factory and the specific changes. Summary of the invention

[0004] The purpose of this application is to provide a method, device and system for measuring the timing clock synchronization error, which can simply and conveniently measure the timing clock synchronization error between optical radar and GNSS.

[0005] In a first aspect, the present application provides a method for measuring a timing clock synchronization error, which is applied to a host computer, wherein the host computer is electrically connected to a laser radar and a photoelectric pulse timer, the laser radar is electrically connected to a GNSS receiver to be measured, the photoelectric pulse timer is electrically connected to a reference GNSS receiver, a reflective mark is arranged in front of the laser radar, a light-transmitting hole is arranged in the center of the reflective mark, a photoelectric sensor of the photoelectric pulse timer is arranged on a side of the reflective mark facing away from the laser radar and facing the light-transmitting hole, and the laser radar is arranged on a rotating platform, and the rotating platform is used to drive the laser radar to swing back and forth around an axis so that the light beam of the laser radar can sweep through the light-transmitting hole;

[0006] The method for measuring the timing clock synchronization error comprises the steps of:

[0007] A1. During the reciprocating swing of the laser radar, the point cloud data collected by the laser radar is obtained, and the timing data of the reference GNSS receiver is recorded each time the photoelectric sensor is illuminated by the laser radar to obtain a first time series;

[0008] A2. Determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the measured GNSS receiver;

[0009] A3. Calculate the timing clock synchronization error between the laser radar and the GNSS receiver under test according to the time difference between each time data of the first time series and the second time series.

[0010] By introducing a photoelectric pulse timer and a reference GNSS receiver, the time of the reference GNSS receiver when the laser radar sweeps over the center of the reflective mark is collected as a reference time, which is used to compare with the collection time of the laser radar sweeping over the center of the reflective mark obtained by the laser radar according to the timing time data of the GNSS receiver under test. Since the time accuracy of the reference GNSS receiver and the GNSS receiver under test is very high, the time error between the reference GNSS receiver and the GNSS receiver under test can be regarded as zero. Therefore, the error between the reference time and the collection time is the timing clock synchronization error between the laser radar and the GNSS receiver under test. Measuring the timing clock synchronization error between the laser radar and the GNSS receiver under test through the above process is simple and convenient, and the measurement result has good accuracy.

[0011] Preferably, step A2 comprises:

[0012] Comparing the coordinates of each cloud point in the point cloud data with the known coordinates of the light-transmitting hole to determine a target cloud point corresponding to the light-transmitting hole;

[0013] The acquisition time data of each of the target cloud points is extracted, and the acquisition time data is sorted in ascending order according to chronological order to obtain a second time series.

[0014] Preferably, step A3 comprises:

[0015] A301. Calculate the time difference between each time data of the first time series and the second time series;

[0016] A302. Calculate the average value of the time difference as the timing clock synchronization error between the laser radar and the GNSS receiver under test.

[0017] By calculating the average value of multiple time differences as the timing clock synchronization error, it is helpful to improve the accuracy of the measurement results.

[0018] Preferably, after step A301 and before step A302, the method further includes:

[0019] A303. Eliminate abnormal time differences.

[0020] By eliminating the abnormal time difference, large measurement errors caused by the existence of the abnormal time difference can be avoided, thereby further improving the accuracy of the measurement results.

[0021] Preferably, steps A1-A3 are performed multiple times to calculate multiple timing clock synchronization errors;

[0022] The method for measuring the timing clock synchronization error also includes the steps of:

[0023] A4. Calculate the average value of the timing clock synchronization error as the final timing clock synchronization error.

[0024] In a second aspect, the present application provides a device for measuring a timing clock synchronization error, which is applied to a host computer, wherein the host computer is electrically connected to a laser radar and a photoelectric pulse timer, the laser radar is electrically connected to a GNSS receiver to be measured, the photoelectric pulse timer is electrically connected to a reference GNSS receiver, a reflective mark is arranged in front of the laser radar, a light-transmitting hole is arranged in the center of the reflective mark, a photoelectric sensor of the photoelectric pulse timer is arranged on a side of the reflective mark facing away from the laser radar and facing the light-transmitting hole, and the laser radar is arranged on a rotating platform, and the rotating platform is used to drive the laser radar to swing back and forth around an axis so that the light beam of the laser radar can sweep through the light-transmitting hole;

[0025] The measuring device of the timing clock synchronization error comprises:

[0026] A first acquisition module is used to acquire point cloud data collected by the laser radar during the reciprocating swing of the laser radar, and record the timing data of the reference GNSS receiver each time the photoelectric sensor is irradiated by the laser radar to obtain a first time series;

[0027] A second acquisition module is used to determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the measured GNSS receiver;

[0028] The first calculation module is used to calculate the timing clock synchronization error between the laser radar and the GNSS receiver under test according to the time difference between each time data of the first time series and the second time series.

[0029] The above process is used to measure the timing clock synchronization error between the lidar and the GNSS receiver under test, which is simple and convenient, and the measurement result is accurate.

[0030] Preferably, the second acquisition module determines a target cloud point corresponding to the light-transmitting hole in the point cloud data to acquire acquisition time data of the target cloud point, and when forming a second time series, executes:

[0031] Comparing the coordinates of each cloud point in the point cloud data with the known coordinates of the light-transmitting hole to determine a target cloud point corresponding to the light-transmitting hole;

[0032] The acquisition time data of each of the target cloud points is extracted, and the acquisition time data is sorted in ascending order according to chronological order to obtain a second time series.

[0033] Preferably, when the first calculation module calculates the timing clock synchronization error between the laser radar and the measured GNSS receiver according to the time difference between each time data of the first time series and the second time series, the first calculation module executes:

[0034] Calculating the time difference between each time data of the first time series and the second time series;

[0035] The average value of the time difference is calculated as the timing clock synchronization error between the laser radar and the measured GNSS receiver.

[0036] Preferably, after calculating the time difference between each time data of the first time series and the second time series, and before calculating the average value of the time difference as the timing clock synchronization error between the laser radar and the measured GNSS receiver, the first calculation module executes:

[0037] Eliminate abnormal time differences.

[0038] In a third aspect, the present application provides a measurement system for a timing clock synchronization error, comprising a host computer, a laser radar, a photoelectric pulse timer, a GNSS receiver under test, a reference GNSS receiver, a reflective marker and a rotating platform, wherein the laser radar, the photoelectric pulse timer and the rotating platform are all electrically connected to the host computer, the GNSS receiver under test is electrically connected to the laser radar, and the reference GNSS receiver is electrically connected to the photoelectric pulse timer; the reflective marker is arranged in front of the laser radar, and a light-transmitting hole is arranged in the center of the reflective marker, and a photoelectric sensor of the photoelectric pulse timer is arranged on a side of the reflective marker facing away from the laser radar and facing the light-transmitting hole; the laser radar is arranged on the rotating platform, and the rotating platform is used to drive the laser radar to swing back and forth around an axis so that the light beam of the laser radar can sweep through the light-transmitting hole;

[0039] The host computer is used to execute:

[0040] A1. During the reciprocating swing of the laser radar, the point cloud data collected by the laser radar is obtained, and the timing data of the reference GNSS receiver is recorded each time the photoelectric sensor is illuminated by the laser radar to obtain a first time series;

[0041] A2. Determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the measured GNSS receiver;

[0042] A3. Calculate the timing clock synchronization error between the laser radar and the GNSS receiver under test according to the time difference between each time data of the first time series and the second time series.

[0043] Beneficial effects:

[0044] The method, device and system for measuring the timing clock synchronization error provided by the present application introduce a photoelectric pulse timer and a reference GNSS receiver to collect the time of the reference GNSS receiver when the laser radar sweeps over the center of the reflective mark as a reference time, which is used to compare with the collection time of the laser radar sweeping over the center of the reflective mark obtained by the laser radar based on the timing time data of the GNSS receiver under test. Since the time accuracy of the reference GNSS receiver and the GNSS receiver under test is very high, the time error between the reference GNSS receiver and the GNSS receiver under test can be regarded as zero. Therefore, the error between the reference time and the collection time is the timing clock synchronization error between the laser radar and the GNSS receiver under test. Measuring the timing clock synchronization error between the laser radar and the GNSS receiver under test through the above process is simple and convenient, and the measurement result has good accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A flowchart of a method for measuring a timing clock synchronization error provided in an embodiment of the present application.

[0046] Figure 2 A schematic diagram of the structure of a device for measuring timing clock synchronization error provided in an embodiment of the present application.

[0047] Figure 3 A schematic diagram of the structure of a timing clock synchronization error measurement system provided in an embodiment of the present application.

[0048] Explanation of reference numerals: 1. first acquisition module; 2. second acquisition module; 3. first calculation module; 100. host computer; 200. laser radar; 300. photoelectric pulse timer; 400. GNSS receiver under test; 500. reference GNSS receiver; 600. reflective marker; 700. rotating platform. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0050] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0051] Please refer to Figure 1 , Figure 1 A method for measuring a timing clock synchronization error in some embodiments of the present application is applied to a host computer, the host computer is electrically connected to a laser radar and a photoelectric pulse timer, the laser radar is electrically connected to a GNSS receiver to be measured, the photoelectric pulse timer is electrically connected to a reference GNSS receiver, a reflective mark is arranged in front of the laser radar, a light-transmitting hole is arranged in the center of the reflective mark, a photoelectric sensor of the photoelectric pulse timer is arranged on the side of the reflective mark facing away from the laser radar and facing the light-transmitting hole, the laser radar is arranged on a rotating platform, and the rotating platform is used to drive the laser radar to swing back and forth around an axis so that the laser radar light beam can sweep through the light-transmitting hole;

[0052] The method for measuring the timing clock synchronization error comprises the steps of:

[0053] A1. During the reciprocating swing of the laser radar, the point cloud data collected by the laser radar is obtained, and each time the photoelectric sensor is illuminated by the laser radar is recorded, and the timing data of the GNSS receiver (the timing data is collected by the photoelectric pulse timer) is compared to obtain a first time series;

[0054] A2. Determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing data of the GNSS receiver under test;

[0055] A3. Calculate the timing clock synchronization error between the laser radar and the GNSS receiver under test based on the time difference between each time data of the first time series and the second time series.

[0056] By introducing a photoelectric pulse timer and a reference GNSS receiver, the time of the reference GNSS receiver when the laser radar sweeps over the center of the reflective mark is collected as a reference time, which is used to compare with the collection time of the laser radar sweeping over the center of the reflective mark obtained by the laser radar according to the timing time data of the GNSS receiver under test. Since the time accuracy of the reference GNSS receiver and the GNSS receiver under test is very high, the time error between the reference GNSS receiver and the GNSS receiver under test can be regarded as zero. Therefore, the error between the reference time and the collection time is the timing clock synchronization error between the laser radar and the GNSS receiver under test. Measuring the timing clock synchronization error between the laser radar and the GNSS receiver under test through the above process is simple and convenient, and the measurement result has good accuracy.

[0057] Among them, the measurement method of the timing clock synchronization error can be based on Figure 3 The timing clock synchronization error measurement system is implemented as shown.

[0058] In some embodiments, the rotating platform is used to drive the laser radar to swing back and forth around a vertical axis, so that the laser radar swings back and forth in a horizontal plane to scan the point cloud. However, it is not limited thereto, and can also swing back and forth in a vertical plane or in an inclined plane.

[0059] Among them, the light-transmitting hole at the processing center of the reflective mark is light-transmitting, while the other parts are not light-transmitting, so that when the laser radar laser is irradiated on the reflective mark (non-center position), it can reliably reflect light to form cloud points. Whenever the laser radar laser scans the light-transmitting hole, it will trigger the photoelectric sensor of the photoelectric pulse timer, and the photoelectric pulse timer will immediately record the timing data of the reference GNSS receiver at that time and upload it to the host computer. Since the timing accuracy of the photoelectric pulse timer can reach sub-microsecond level, the timing data recorded by it can be used as an accurate reference time.

[0060] Among them, the timing time data in the first time series is sorted in ascending order of time.

[0061] Preferably, step A2 comprises:

[0062] A201. Compare the coordinates of each cloud point in the point cloud data with the known coordinates of the light-transmitting hole to determine the target cloud point corresponding to the light-transmitting hole;

[0063] A202. Extract the acquisition time data of each target cloud point, and sort the acquisition time data in ascending order according to chronological order to obtain a second time series.

[0064] The coordinates of the light-transmitting hole (relative to the coordinates of the laser radar) can be measured in advance and are therefore known.

[0065] There are no other obstructions between the laser radar and the reflective mark. Here, other reflective objects except the reflective mark are called background objects. The depth of the cloud point formed by the reflection of the reflective mark (the depth here refers to the distance from the cloud point to the laser radar) is smaller than the depth of the cloud point formed by the reflection of other background objects. Therefore, in step A201, the cloud points of the reflective mark can be first screened out according to the distance from each cloud point to the laser radar (for example, the cloud points whose distance is less than the preset distance threshold are regarded as the cloud points of the reflective mark), recorded as the first cloud points, and then each first cloud point is compared with the known light-transmitting hole coordinates to determine the target cloud point corresponding to the light-transmitting hole; thereby, the amount of data processing can be greatly reduced and the processing efficiency can be improved.

[0066] Among them, since the laser radar can obtain multiple continuous first cloud points each time it scans the reflective mark, after screening, multiple segments of continuous first cloud points are obtained. Among them, since the laser radar emits laser in a pulsed manner with a preset frequency, when scanning the light-transmitting hole of the reflective mark, it may be in the emission interval of the laser pulse. Therefore, not every segment of continuous first cloud points contains the target cloud point. However, each timing time data in the first time series must fall within the time range of one segment of continuous first cloud points (that is, the time range from the acquisition time of the first first cloud point of the segment to the acquisition time of the last first cloud point of the segment of continuous first cloud points). Therefore, when comparing each first cloud point with the known light-transmitting hole coordinates to determine the target cloud point corresponding to the light-transmitting hole, the time range of each segment of continuous first cloud points can be determined first, and then each segment of continuous first cloud points corresponding to the time range into which each timing time data in the first time series falls is taken as a valid cloud point segment, and finally the first cloud point closest to the light-transmitting hole (that is, the first cloud point with the smallest distance from the light-transmitting hole) is selected from each valid cloud point segment as the target cloud point. Thus, a one-to-one correspondence is achieved between each time data of the first time series and the second time series.

[0067] The laser radar will calculate and record the acquisition time data of each cloud point based on the timing data of the GNSS receiver under test. The host computer can directly read the acquisition time data of each target cloud point from the laser radar.

[0068] Specifically, step A3 includes:

[0069] A301. Calculate the time difference between each time data of the first time series and the second time series;

[0070] A302. Calculate the average value of the time difference as the timing clock synchronization error between the lidar and the GNSS receiver under test.

[0071] By calculating the average value of multiple time differences as the timing clock synchronization error, it is helpful to improve the accuracy of the measurement results.

[0072] In step A301, the time difference between each time data of the first time series and the second time series is calculated by the following formula:

[0073] ΔTi=Tci–Tei;

[0074] Wherein, ΔTi is the time difference between the i-th time data of the first time series and the i-th time data of the second time series, Tci is the i-th time data of the first time series (i.e., the i-th timing time data), and Tei is the i-th time data of the second time series (i.e., the i-th acquisition time data).

[0075] Among them, in step A302, the timing clock synchronization error between the laser radar and the GNSS receiver under test is calculated by the following formula:

[0076] ΔT=(∑ΔTi) / n;

[0077] Wherein, ΔT is the timing clock synchronization error between the lidar and the GNSS receiver under test, and n is the total number of time differences.

[0078] In some preferred implementations, after step A301 and before step A302, the method further includes:

[0079] A303. Eliminate abnormal time differences.

[0080] The abnormal time difference refers to a time difference that is greater than a preset time difference threshold (which can be set according to actual needs) or greater than 3σ (σ is the standard deviation of the time difference).

[0081] By eliminating the abnormal time difference, large measurement errors caused by the existence of the abnormal time difference can be avoided, thereby further improving the accuracy of the measurement results.

[0082] In some implementations, if the proportion of the number of eliminated abnormal time differences in the total number of time differences exceeds a preset proportion threshold (which can be set according to actual needs), the current measurement is determined to be invalid and the measurement is performed again.

[0083] In some implementations, steps A1-A3 are performed once, and the calculated timing clock synchronization error is used as the final timing clock synchronization error.

[0084] In some other implementations, steps A1-A3 are performed multiple times to calculate multiple timing clock synchronization errors;

[0085] Furthermore, the method for measuring the timing clock synchronization error also includes the steps of:

[0086] A4. Calculate the average value of the timing clock synchronization error as the final timing clock synchronization error.

[0087] By repeating steps A1-A3 multiple times to obtain multiple timing clock synchronization errors, and finally taking the average value of these timing clock synchronization errors as the final timing clock synchronization error, the accuracy of the measurement result can be further improved.

[0088] As can be seen from the above, the method for measuring the timing clock synchronization error obtains the point cloud data collected by the laser radar during the reciprocating swing of the laser radar, and records each time the photoelectric sensor is irradiated by the laser radar, and compares it with the timing time data of the GNSS receiver to obtain a first time series; the target cloud point corresponding to the light-transmitting hole is determined in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the GNSS receiver under test; the timing clock synchronization error between the laser radar and the GNSS receiver under test is calculated according to the time difference between each time data of the first time series and the second time series; thereby, the timing clock synchronization error between the laser radar and the GNSS receiver under test can be measured simply and conveniently.

[0089] refer to Figure 2 The present application provides a device for measuring the synchronization error of a timing clock, which is applied to a host computer. The host computer is electrically connected to a laser radar and a photoelectric pulse timer. The laser radar is electrically connected to a GNSS receiver to be measured. The photoelectric pulse timer is electrically connected to a reference GNSS receiver. A reflective mark is arranged in front of the laser radar, and a light-transmitting hole is arranged in the center of the reflective mark. The photoelectric sensor of the photoelectric pulse timer is arranged on the side of the reflective mark facing away from the laser radar and facing the light-transmitting hole. The laser radar is arranged on a rotating platform, and the rotating platform is used to drive the laser radar to swing back and forth around an axis so that the laser radar light beam can sweep through the light-transmitting hole.

[0090] The measuring device of the timing clock synchronization error includes:

[0091] The first acquisition module 1 is used to acquire the point cloud data collected by the laser radar during the reciprocating swing of the laser radar, and record the time data of the photoelectric sensor being irradiated by the laser radar each time, and compare it with the timing time data of the GNSS receiver (the timing time data is collected by the photoelectric pulse timer) to obtain a first time series;

[0092] The second acquisition module 2 is used to determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing data of the GNSS receiver under test;

[0093] The first calculation module 3 is used to calculate the timing clock synchronization error between the laser radar and the GNSS receiver under test according to the time difference between each time data of the first time series and the second time series.

[0094] The above process is used to measure the timing clock synchronization error between the lidar and the GNSS receiver under test, which is simple and convenient, and the measurement result is accurate.

[0095] In some embodiments, the rotating platform is used to drive the laser radar to swing back and forth around a vertical axis, so that the laser radar swings back and forth in a horizontal plane to scan the point cloud. However, it is not limited thereto, and can also swing back and forth in a vertical plane or in an inclined plane.

[0096] Among them, the light-transmitting hole at the processing center of the reflective mark is light-transmitting, while the other parts are not light-transmitting, so that when the laser radar laser is irradiated on the reflective mark (non-center position), it can reliably reflect light to form cloud points. Whenever the laser radar laser scans the light-transmitting hole, it will trigger the photoelectric sensor of the photoelectric pulse timer, and the photoelectric pulse timer will immediately record the timing data of the reference GNSS receiver at that time and upload it to the host computer. Since the timing accuracy of the photoelectric pulse timer can reach sub-microsecond level, the timing data recorded by it can be used as an accurate reference time.

[0097] Among them, the timing time data in the first time series is sorted in ascending order of time.

[0098] Preferably, the second acquisition module 2 determines the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point, and when forming the second time series, executes:

[0099] Compare the coordinates of each cloud point in the point cloud data with the known coordinates of the light-transmitting hole to determine the target cloud point corresponding to the light-transmitting hole;

[0100] The acquisition time data of each target cloud point is extracted, and the acquisition time data is sorted in ascending order according to the chronological order to obtain a second time series.

[0101] The coordinates of the light-transmitting hole (relative to the coordinates of the laser radar) can be measured in advance and are therefore known.

[0102] There are no other obstructions between the laser radar and the reflective mark. Here, other reflective objects except the reflective mark are called background objects. The depth of the cloud point formed by the reflection of the reflective mark (the depth here refers to the distance from the cloud point to the laser radar) is smaller than the depth of the cloud point formed by the reflection of other background objects. Therefore, when the second acquisition module 2 compares the coordinates of each cloud point in the point cloud data with the known coordinates of the light-transmitting hole to determine the target cloud point corresponding to the light-transmitting hole, it can first filter out the cloud point of the reflective mark according to the distance from each cloud point to the laser radar (for example, the cloud point whose distance is less than the preset distance threshold is taken as the cloud point of the reflective mark), record it as the first cloud point, and then compare each first cloud point with the known light-transmitting hole coordinates to determine the target cloud point corresponding to the light-transmitting hole; thereby, the amount of data processing can be greatly reduced and the processing efficiency can be improved.

[0103] Among them, since the laser radar can obtain multiple continuous first cloud points each time it scans the reflective mark, after screening, multiple segments of continuous first cloud points are obtained. Among them, since the laser radar emits laser in a pulsed manner with a preset frequency, when scanning the light-transmitting hole of the reflective mark, it may be in the emission interval of the laser pulse. Therefore, not every segment of continuous first cloud points contains the target cloud point. However, each timing time data in the first time series must fall within the time range of one segment of continuous first cloud points (that is, the time range from the acquisition time of the first first cloud point of the segment to the acquisition time of the last first cloud point of the segment of continuous first cloud points). Therefore, when comparing each first cloud point with the known light-transmitting hole coordinates to determine the target cloud point corresponding to the light-transmitting hole, the time range of each segment of continuous first cloud points can be determined first, and then each segment of continuous first cloud points corresponding to the time range into which each timing time data in the first time series falls is taken as a valid cloud point segment, and finally the first cloud point closest to the light-transmitting hole (that is, the first cloud point with the smallest distance from the light-transmitting hole) is selected from each valid cloud point segment as the target cloud point. Thus, a one-to-one correspondence is achieved between each time data of the first time series and the second time series.

[0104] The laser radar will calculate and record the acquisition time data of each cloud point according to the timing data of the GNSS receiver under test, and the second acquisition module 2 can directly read the acquisition time data of each target cloud point from the laser radar.

[0105] Specifically, when the first calculation module 3 calculates the timing clock synchronization error between the laser radar and the measured GNSS receiver according to the time difference between each time data of the first time series and the second time series, it executes:

[0106] Calculate the time difference between each time data of the first time series and the second time series;

[0107] The average value of the time difference is calculated as the timing clock synchronization error between the lidar and the GNSS receiver under test.

[0108] By calculating the average value of multiple time differences as the timing clock synchronization error, it is helpful to improve the accuracy of the measurement results.

[0109] The time difference between each time data of the first time series and the second time series is calculated by the following formula:

[0110] ΔTi=Tci–Tei;

[0111] Wherein, ΔTi is the time difference between the i-th time data of the first time series and the i-th time data of the second time series, Tci is the i-th time data of the first time series (i.e., the i-th timing time data), and Tei is the i-th time data of the second time series (i.e., the i-th acquisition time data).

[0112] The timing clock synchronization error between the lidar and the GNSS receiver under test is calculated using the following formula:

[0113] ΔT=(∑ΔTi) / n;

[0114] Wherein, ΔT is the timing clock synchronization error between the lidar and the GNSS receiver under test, and n is the total number of time differences.

[0115] In some preferred embodiments, after calculating the time difference between each time data of the first time series and the second time series, and before calculating the average value of the time difference as the timing clock synchronization error between the laser radar and the measured GNSS receiver, the first calculation module 3 executes:

[0116] Eliminate abnormal time differences.

[0117] The abnormal time difference refers to a time difference that is greater than a preset time difference threshold (which can be set according to actual needs) or greater than 3σ (σ is the standard deviation of the time difference).

[0118] By eliminating the abnormal time difference, large measurement errors caused by the existence of the abnormal time difference can be avoided, thereby further improving the accuracy of the measurement results.

[0119] In some implementations, if the proportion of the number of eliminated abnormal time differences in the total number of time differences exceeds a preset proportion threshold (which can be set according to actual needs), the current measurement is determined to be invalid and the measurement is performed again.

[0120] In some implementations, during one measurement process, the first acquisition module 1, the second acquisition module 2, and the first calculation module 3 execute corresponding functional steps once to use the calculated timing clock synchronization error as the final timing clock synchronization error.

[0121] In some other implementations, during one measurement process, the first acquisition module 1, the second acquisition module 2 and the first calculation module 3 cyclically execute corresponding functional steps for multiple times to calculate and obtain multiple timing clock synchronization errors;

[0122] Furthermore, the measuring device for the timing clock synchronization error also includes:

[0123] The second calculation module is used to calculate the average value of the timing clock synchronization error as the final timing clock synchronization error.

[0124] The first acquisition module 1, the second acquisition module 2 and the first calculation module 3 are used to repeat the corresponding functional steps multiple times to obtain multiple timing clock synchronization errors, and finally the average value of these timing clock synchronization errors is used as the final timing clock synchronization error, which can further improve the accuracy of the measurement result.

[0125] As can be seen from the above, the measuring device of the timing clock synchronization error obtains the point cloud data collected by the laser radar during the reciprocating swing of the laser radar, and records each time the photoelectric sensor is irradiated by the laser radar, and compares it with the timing time data of the GNSS receiver to obtain a first time series; determines the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the GNSS receiver under test; the timing clock synchronization error between the laser radar and the GNSS receiver under test is calculated according to the time difference between each time data of the first time series and the second time series; thereby, the timing clock synchronization error between the laser radar and the GNSS receiver under test can be measured simply and conveniently.

[0126] refer to Figure 3The present application provides a measurement system for timing clock synchronization error, including a host computer 100, a laser radar 200, a photoelectric pulse timer 300, a GNSS receiver under test 400, a reference GNSS receiver 500, a reflective marker 600 and a rotating platform 700, wherein the laser radar 200, the photoelectric pulse timer 300 and the rotating platform 700 are all electrically connected to the host computer 100, the GNSS receiver under test 400 is electrically connected to the laser radar 200, and the reference GNSS receiver 500 is electrically connected to the photoelectric pulse timer. The laser radar 200 is electrically connected to the device 300; the reflective mark 600 is arranged in front of the laser radar 200, and a light-transmitting hole is arranged in the center of the reflective mark 600, and the photoelectric sensor of the photoelectric pulse timer 300 is arranged on the side of the reflective mark 600 facing away from the laser radar 200 and facing the light-transmitting hole (the photoelectric sensor is close to the reflective mark 600); the laser radar 200 is arranged on the rotating platform 700, and the rotating platform 700 is used to drive the laser radar 200 to swing back and forth around an axis so that the light beam of the laser radar 200 can sweep through the light-transmitting hole;

[0127] The host computer 100 is used to execute:

[0128] A1. During the reciprocating swing of the laser radar, the point cloud data collected by the laser radar is obtained, and each time the photoelectric sensor is illuminated by the laser radar is recorded, and the timing data of the GNSS receiver (the timing data is collected by the photoelectric pulse timer) is compared to obtain the first time series (the specific process is referred to the previous text);

[0129] A2. Determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing data of the GNSS receiver under test (refer to the previous text for the specific process);

[0130] A3. Calculate the timing clock synchronization error between the lidar and the GNSS receiver under test based on the time difference between each time data of the first time series and the second time series (refer to the previous text for the specific process).

[0131] The reflective mark 600 is a mark plate, the surface of which is coated with a reflective coating, and a light-transmitting hole is provided in the center of the mark plate.

[0132] Among them, the photoelectric pulse timer 300 is a prior art and will not be described in detail here.

[0133] The rotating platform 700 includes a turntable for mounting the laser radar 200 and a servo motor for driving the turntable to rotate back and forth. The output shaft of the servo motor can be directly connected to the turntable, or connected to the turntable through a transmission mechanism (gear transmission mechanism, belt transmission mechanism, chain transmission mechanism, etc.).

[0134] The tested GNSS receiver 400 and the control GNSS receiver 500 are GNSS receivers of the same model.

[0135] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0136] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0137] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0138] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0139] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for measuring a timing clock synchronization error, characterized in that: Applied to a host computer, the host computer is electrically connected to a laser radar and a photoelectric pulse timer, the laser radar is electrically connected to a GNSS receiver under test, the photoelectric pulse timer is electrically connected to a reference GNSS receiver, a reflective mark is arranged in front of the laser radar, a light-transmitting hole is arranged in the center of the reflective mark, a photoelectric sensor of the photoelectric pulse timer is arranged on the side of the reflective mark facing away from the laser radar and facing the light-transmitting hole, the laser radar is arranged on a rotating platform, and the rotating platform is used to drive the laser radar to swing back and forth around an axis so that the light beam of the laser radar can sweep through the light-transmitting hole; The method for measuring the timing clock synchronization error comprises the steps of: A1. During the reciprocating swing of the laser radar, the point cloud data collected by the laser radar is obtained, and the timing data of the reference GNSS receiver is recorded each time the photoelectric sensor is illuminated by the laser radar to obtain a first time series; A2. Determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the measured GNSS receiver; A3. Calculate the timing clock synchronization error between the laser radar and the GNSS receiver under test according to the time difference between each time data of the first time series and the second time series.

2. The method for measuring the timing clock synchronization error according to claim 1, characterized in that: Step A2 includes: Comparing the coordinates of each cloud point in the point cloud data with the known coordinates of the light-transmitting hole to determine a target cloud point corresponding to the light-transmitting hole; The acquisition time data of each of the target cloud points is extracted, and the acquisition time data is sorted in ascending order according to chronological order to obtain a second time series.

3. The method for measuring the timing clock synchronization error according to claim 1, characterized in that: Step A3 includes: A301. Calculate the time difference between each time data of the first time series and the second time series; A302. Calculate the average value of the time difference as the timing clock synchronization error between the laser radar and the GNSS receiver under test.

4. The method for measuring the timing clock synchronization error according to claim 3, characterized in that: After step A301 and before step A302, the method further includes: A303. Eliminate abnormal time differences.

5. The method for measuring the timing clock synchronization error according to claim 1, characterized in that: Execute steps A1-A3 multiple times to calculate multiple timing clock synchronization errors; The method for measuring the timing clock synchronization error also includes the steps of: A4. Calculate the average value of the timing clock synchronization error as the final timing clock synchronization error.

6. A device for measuring a timing clock synchronization error, characterized in that: Applied to a host computer, the host computer is electrically connected to a laser radar and a photoelectric pulse timer, the laser radar is electrically connected to a GNSS receiver under test, the photoelectric pulse timer is electrically connected to a reference GNSS receiver, a reflective mark is arranged in front of the laser radar, a light-transmitting hole is arranged in the center of the reflective mark, a photoelectric sensor of the photoelectric pulse timer is arranged on the side of the reflective mark facing away from the laser radar and facing the light-transmitting hole, the laser radar is arranged on a rotating platform, and the rotating platform is used to drive the laser radar to swing back and forth around an axis so that the light beam of the laser radar can sweep through the light-transmitting hole; The measuring device of the timing clock synchronization error comprises: A first acquisition module is used to acquire point cloud data collected by the laser radar during the reciprocating swing of the laser radar, and record the timing data of the reference GNSS receiver each time the photoelectric sensor is irradiated by the laser radar to obtain a first time series; A second acquisition module is used to determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the measured GNSS receiver; The first calculation module is used to calculate the timing clock synchronization error between the laser radar and the GNSS receiver under test according to the time difference between each time data of the first time series and the second time series.

7. The device for measuring the timing clock synchronization error according to claim 6, characterized in that: The second acquisition module determines the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point, and when forming the second time series, executes: Comparing the coordinates of each cloud point in the point cloud data with the known coordinates of the light-transmitting hole to determine a target cloud point corresponding to the light-transmitting hole; The acquisition time data of each of the target cloud points is extracted, and the acquisition time data is sorted in ascending order according to chronological order to obtain a second time series.

8. The device for measuring the timing clock synchronization error according to claim 6, characterized in that: When the first calculation module calculates the timing clock synchronization error between the laser radar and the measured GNSS receiver according to the time difference between each time data of the first time series and the second time series, the first calculation module executes: Calculating the time difference between each time data of the first time series and the second time series; The average value of the time difference is calculated as the timing clock synchronization error between the laser radar and the measured GNSS receiver.

9. The device for measuring the timing clock synchronization error according to claim 8, characterized in that: After calculating the time difference between each time data of the first time series and the second time series, and before calculating the average value of the time difference as the timing clock synchronization error between the laser radar and the measured GNSS receiver, the first calculation module executes: Eliminate abnormal time differences.

10. A system for measuring timing clock synchronization error, characterized in that: It includes a host computer, a laser radar, a photoelectric pulse timer, a GNSS receiver under test, a reference GNSS receiver, a reflective mark and a rotating platform, wherein the laser radar, the photoelectric pulse timer and the rotating platform are all electrically connected to the host computer, the GNSS receiver under test is electrically connected to the laser radar, and the reference GNSS receiver is electrically connected to the photoelectric pulse timer; the reflective mark is arranged in front of the laser radar, and a light-transmitting hole is arranged in the center of the reflective mark, and the photoelectric sensor of the photoelectric pulse timer is arranged on the side of the reflective mark facing away from the laser radar and facing the light-transmitting hole; the laser radar is arranged on the rotating platform, and the rotating platform is used to drive the laser radar to swing back and forth around an axis so that the light beam of the laser radar can sweep through the light-transmitting hole; The host computer is used to execute: A1. During the reciprocating swing of the laser radar, the point cloud data collected by the laser radar is obtained, and the timing data of the reference GNSS receiver is recorded each time the photoelectric sensor is illuminated by the laser radar to obtain a first time series; A2. Determine the target cloud point corresponding to the light-transmitting hole in the point cloud data to obtain the acquisition time data of the target cloud point to form a second time series; the acquisition time data of the target cloud point is calculated by the laser radar according to the timing time data of the measured GNSS receiver; A3. Calculate the timing clock synchronization error between the laser radar and the GNSS receiver under test according to the time difference between each time data of the first time series and the second time series.

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