Target distance adjustable laser radar calibration system and calibration method

Abstract

The embodiment of the invention discloses a target distance adjustable laser radar calibration system and calibration method, targets with different reflectivity are installed on a target tool table, the target tool table slides on a guide rail and can rotate to switch the targets, and the distance between the targets and a to-be-calibrated laser radar is measured through a range finder. During calibration, the upper computer controls the target tool table to slide along the guide rail and receives the distance measured by the distance measuring instrument, controls the target tool table to stop moving when the distance is equal to the calibration distance, controls the to-be-calibrated laser radar to measure the distance of the target to obtain distance measuring data, receives the distance measuring data of the to-be-calibrated laser radar and stores the distance measuring data and the calibration distance. The targets are not required to be manually placed and the targets with different reflectivity are not required to be manually replaced according to the calibration distance, the distance of the targets on the target tool table can be accurately controlled and the targets with different reflectivity can be automatically switched through the range finder and the upper computer, the accuracy of the distance from the targets to the to-be-calibrated laser radar is improved, manual operation is not required, and the working efficiency is improved. And the calibration data acquisition efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser radar calibration, and in particular to a laser radar calibration system and method with adjustable target distance. BACKGROUND

[0002] In the research and production process of a laser radar, a standard distance needs to be calibrated. The calibration method is to collect original measurement data of a target with different reflectivity at different distances by using the laser radar.

[0003] In the existing laser radar calibration, a large number of targets with different reflectivity are needed. A target with the same reflectivity is placed at different distances by using the laser radar to measure the distance, and then a target with another reflectivity is replaced to repeat the above process. On the one hand, the distance accuracy is low when the target is placed manually, and on the other hand, the efficiency of data collection and distance measurement is low when the target with different reflectivity is replaced manually. SUMMARY

[0004] The present application provides a laser radar calibration system and method with adjustable target distance. The target does not need to be placed and replaced manually, the distance from the target to the laser radar can be accurately controlled, and the accuracy and efficiency of laser radar calibration are improved.

[0005] In a first aspect, the present application provides a laser radar calibration system with adjustable target distance, comprising: a calibration tool table and a guide rail arranged outside the calibration tool table; a target tool table for mounting targets with different reflectivity, the target tool table being slidably arranged on the guide rail and switching targets with different reflectivity by a rotating mechanism; a radar tool table arranged on the calibration tool table and a distance meter, the distance meter being used to measure the distance from the target to a laser radar to be calibrated mounted on the radar tool table; a host computer, the host computer being in communication with the distance meter, the target tool table and the laser radar to be calibrated mounted on the radar tool table; the host computer is used to: control the target tool table to slide along the guide rail and receive the distance measured by the distance meter; control the target tool table to stop moving when the distance is equal to a preset calibration distance; control the laser radar to be calibrated to measure the distance to the target and obtain distance measurement data; receive the distance measurement data of the laser radar to be calibrated and store the distance measurement data and the calibration distance.

[0006] Optionally, a camera arranged on the calibration tool table is further included, the camera being connected with the host computer. The host computer is further configured to: control the target tool table to move to a maximum calibration distance, and control the to-be-calibrated laser radar to emit a laser signal; control the camera to capture a target image of the target; determine whether the target image includes a light spot area; if not, control the radar tool table to rotate in a horizontal and / or vertical direction until the captured target image includes a light spot area.

[0007] Optionally, the host computer is further configured to: control the target tool table to slide to the radar tool table to a zero position.

[0008] Optionally, the host computer is further configured to: when receiving an instruction to switch the target, control a rotating mechanism of the target tool table to drive the target tool table to rotate to switch to a target reflectivity target.

[0009] Optionally, a sliding distance of the target tool table on the guide rail is 10-50000 mm.

[0010] Optionally, a width of the target installed on the target tool table is 10-2000 mm, and a height is 30-2000 mm.

[0011] Optionally, an adjustment range of the radar tool table in a pitch angle is -20°-20°, and a horizontal rotation angle is 0°-360°.

[0012] In a second aspect, an embodiment of the present application provides a laser radar calibration method, applied to the laser radar calibration system with a target distance adjustment function according to any one of the first aspect, and the laser radar calibration method comprises: controlling the target tool table to slide along the guide rail, and receiving a distance measured by the distance measuring instrument; controlling the target tool table to stop moving when the distance is equal to a preset calibration distance; controlling the to-be-calibrated laser radar to measure the distance of the target, to obtain distance measurement data; receiving the distance measurement data of the to-be-calibrated laser radar, and storing the distance measurement data and the calibration distance.

[0013] Optionally, before controlling the target tool table to slide along the guide rail and receiving the distance measured by the distance measuring instrument, the laser radar calibration method further comprises: controlling the target tool table to move to a maximum calibration distance, and controlling the to-be-calibrated laser radar to emit a laser signal; controlling the camera to capture a target image of the target; determining whether the target image includes a light spot region; If not, the radar tool table is controlled to rotate in the horizontal and / or vertical direction until the collected target image includes a light spot region.

[0014] Optionally, further comprising: Upon receiving an instruction to switch the target, a rotating mechanism of the target tool table is controlled to drive the target tool table to rotate to switch to a target of a target reflectivity.

[0015] The laser radar calibration system of the embodiment of the present application has a target tool table that is installed with targets of different reflectivities and is slidable on a guide rail and rotatable to switch the targets, and a distance measuring instrument is used to measure the distance from the target to the laser radar to be calibrated installed on the target tool table. In calibration, an upper computer controls the target tool table to slide along the guide rail and receives the distance measured by the distance measuring instrument, controls the target tool table to stop moving when the distance is equal to a preset calibration distance, and controls the laser radar to be calibrated to measure the distance to the target to obtain distance measuring data. The distance measuring data of the laser radar to be calibrated is received and stored, and the target is placed and the target of different reflectivity is replaced without manual operation. The distance of the target on the target tool table and the target of different reflectivity are accurately controlled by the distance measuring instrument and the upper computer, the accuracy of the distance from the target to the laser radar to be calibrated is improved, and manual operation is not required, and the efficiency of calibration data acquisition is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A structural diagram of a laser radar calibration system with adjustable target distance provided by the embodiment of the present application; Figure 2 A structural diagram of a laser radar calibration system with adjustable target distance provided by another embodiment of the present application; Figure 3 A flowchart of a laser radar calibration method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application.

[0018] Figure 1 A structural diagram of a laser radar calibration system with adjustable target distance provided by the embodiment of the present application, which is used to calibrate the distance measuring performance of a laser radar. Specifically, the laser radar is used to measure the distance to a target of different reflectivities at the same distance, and the distance to a target of the same reflectivity at different distances, and the laser radar is calibrated by comparing the measured distance with the real distance. Figure 1The target distance adjustable laser radar calibration system can include a host computer, a calibration tool table 1, a guide rail 2, a target tool table 3, a radar tool table 4, and a range finder 5.

[0019] The calibration tool table 1 can be a component for mounting the radar tool table 4 and the range finder 5, one end of the guide rail 2 can be connected with the calibration tool table 1, the guide rail 2 can be a single guide rail or a double guide rail, the target tool table 3 can slide on the guide rail 2, and the target tool table 3 can include a motor and a sliding mechanism, the target tool table 3 is slidably connected with the guide rail 2 through the sliding mechanism, the sliding mechanism can be driven by the motor, so that the target tool table 3 can slide on the guide rail 2 towards or away from the calibration tool table 1, a plurality of targets with different reflectivities can be mounted on the target tool table 3, and the target tool table 3 can be rotated in the horizontal direction to make the targets with different reflectivities face the calibration tool table 1.

[0020] The radar tool table 4 is used for mounting a laser radar to be calibrated, and the radar tool table 4 is rotatable in the horizontal direction and the vertical direction, that is, the radar tool table 4 is a tool table with adjustable horizontal angle and pitch angle, so that after the laser radar to be calibrated is mounted on the radar tool table 4, the laser radar to be calibrated can emit a laser signal to the target after the radar tool table 4 is rotated in the horizontal and / or vertical direction.

[0021] The range finder 5 can be an instrument capable of high-precision ranging after calibration, such as a laser range finder, and the range finder 5 can range the target on the target tool table 3 to obtain the real distance from the target to the laser radar.

[0022] As shown in Figure 1 The guide rail 2 is arranged outside the calibration tool table 1 and connected with one end of the calibration tool table 1, the target tool table 3 is slidably arranged on the guide rail 2, the radar tool table 4 and the range finder 5 are arranged on the calibration tool table 1, the range finder 5 is used for measuring the distance from the target to the laser radar to be calibrated mounted on the radar tool table, and the host computer communicates with the range finder 5, the target tool table 3, and the laser radar to be calibrated mounted on the radar tool table 4.

[0023] The working principle of the target distance adjustable laser radar calibration system is as follows: One or more calibration distances are pre-configured. When calibrating with a target of the same reflectivity, the host computer controls the target fixture 3 to slide along the guide rail and receives the distance measured by the rangefinder 5. When the distance is equal to each preset calibration distance, the host computer controls the target fixture 3 to stop moving and controls the laser radar to be calibrated to measure the distance of the target to obtain the distance measurement data. The host computer receives the distance measurement data of the laser radar to be calibrated and stores the distance measurement data and calibration distance. This completes the data acquisition required for calibrating the laser radar to be calibrated at different calibration distances with a target of the same reflectivity. Then, the host computer controls the target fixture 3 to rotate and switch to a target with another reflectivity. After the target fixture 3 is returned to zero, the above process is repeated to complete the data acquisition required for calibrating the laser radar to be calibrated at different calibration distances with a target with another reflectivity.

[0024] In the lidar calibration system of this invention, a target fixture is equipped with targets of different reflectivities, which slide and rotate on a guide rail. The distance from the target to the lidar to be calibrated on the fixture is measured by a rangefinder. During calibration, the host computer controls the target fixture to slide along the guide rail and receives the distance measured by the rangefinder. When the distance equals a preset calibration distance, the target fixture stops moving, and the lidar to be calibrated measures the distance to the target to obtain ranging data. The system receives and stores the ranging data and calibration distance. This eliminates the need for manual placement of targets according to the calibration distance and replacement of targets with different reflectivities. The rangefinder and host computer can precisely control the distance to the targets on the fixture and automatically switch between targets with different reflectivities, improving the accuracy of the distance from the target to the lidar to be calibrated. Furthermore, the system eliminates the need for manual operation, thus improving the efficiency of calibration data acquisition.

[0025] like Figure 2 The diagram shows a schematic of a laser radar calibration system with adjustable target distance provided in another embodiment. In this embodiment, the laser radar calibration system also includes a camera 6 mounted on a calibration fixture. The camera 6 is connected to a host computer. The host computer is also used to control the target fixture 3 to slide along the guide rail 2 to the maximum calibration distance, and to control the laser radar to be calibrated to emit laser signals, control the camera 6 to acquire target images, and determine whether the target image includes a light spot area. If not, the radar fixture 4 is controlled to rotate in the horizontal and / or vertical directions until the acquired target image includes the light spot area. The identification of the light spot area in the image can refer to the prior art, which will not be described in detail here.

[0026] This embodiment uses six cameras to capture images of the target and then determines whether the lidar to be calibrated forms a light spot on the target. It can automatically adjust the pitch and horizontal angles of the lidar to be calibrated without the need for manual adjustment, thus improving the automation and efficiency of calibration.

[0027] In one embodiment, the host computer is also used to control the target fixture 6 to move to the zero position on the radar fixture 4 before calibration. For example, before switching targets with different reflectivities for calibration, the host computer controls the target fixture 3 to move to the zero position on the radar fixture 4 to avoid differences between different target fixtures, eliminate calibration errors caused by fixture differences, and improve the accuracy of lidar calibration.

[0028] In another embodiment, the host computer is also used to control the rotation mechanism in the target fixture 3 to rotate when it receives a target switching instruction during the calibration process, so as to drive the target fixture 3 to rotate to switch to the target with the target reflectivity. For example, targets with different reflectivities are installed at different positions on the target fixture 3. Through the mapping between the position and the angle of the target fixture 3, the target fixture 3 is driven to rotate to different angles by the rotation mechanism to correspond to targets with different reflectivities. The host computer can control the rotation mechanism in the target fixture to rotate to a preset angle to switch to the target with the target reflectivity, thereby realizing automatic switching of targets with different reflectivities without the need for manual target replacement and improving the efficiency of lidar calibration.

[0029] It should be noted that the rotating mechanism can be a motor. The host computer can control the motor to rotate the target fixture 3 in the horizontal direction so that targets with different reflectivities are facing the radar fixture 4.

[0030] Optionally, the sliding distance of the target fixture on the guide rail is 10 to 50,000 mm. This sliding distance can be the distance from the target fixture to the lidar to be calibrated. In one embodiment, a limiting mechanism can be installed at both ends of the guide rail to limit the sliding distance of the target fixture on the guide rail to 10 to 50,000 mm. Of course, the limiting mechanism on the guide rail can be adjusted to adjust the range of the sliding distance of the target fixture.

[0031] Optionally, the target mounted on the target fixture has a width of 10-2000mm and a height of 30-2000mm. When calibrating a lidar to be calibrated, the width and height of targets with different reflectivities can be the same or different.

[0032] Optionally, the radar fixture has an elevation angle adjustment range of -20° to 20° and a horizontal rotation angle of 0° to 360° to ensure that the laser radar to be calibrated can form a light spot on the target when the target size is different.

[0033] The target-distance adjustable lidar calibration system in this embodiment performs the following lidar calibration steps: S1. Install the lidar on the lidar fixture; S2. Install targets with different reflectivities on the target fixture table; S3. The host computer controls the target fixture to move along the guide rail toward the laser radar, and the rangefinder's ranging measurement returns to zero. S4. The host computer controls the target fixture to move to the farthest point (maximum calibration distance), controls the lidar to emit laser signals, the camera to collect target images, and controls the lidar fixture to adjust the pitch and horizontal angles so that the laser signal forms a light spot on the target. S5. The host computer controls the target fixture to move along the guide rail toward the laser radar, and the rangefinder's ranging measurement returns to zero. S6. According to one or more pre-configured calibration distances, control the target fixture to slide to each calibration distance in sequence to control the lidar to emit laser signals and collect data; S7. After using a target with one reflectivity to calibrate and collect data for the lidar, control the target fixture to rotate and switch to a target with another reflectivity, return to S3, and repeat S3-S6.

[0034] Through the above steps, the lidar can collect calibration data for targets with different reflectivities and at different distances. There is no need for manual placement of targets at the calibration distance or replacement of targets with different reflectivities. The distance of the targets on the target fixture can be precisely controlled by the rangefinder and the host computer, and targets with different reflectivities can be automatically switched. This improves the accuracy of the distance from the target to the lidar to be calibrated, and the efficiency of calibration data collection is improved without the need for manual operation.

[0035] Figure 3 This is a flowchart illustrating a lidar calibration method provided in an embodiment of the present invention. The lidar calibration method of this embodiment is applied to a lidar calibration system with adjustable target distance provided by the present invention. This method can be executed by a host computer within the lidar calibration system with adjustable target distance. Figure 3 As shown, the lidar calibration method of this embodiment of the invention may specifically include the following steps: S301, control the target fixture to slide along the guide rail and receive the distance measured by the rangefinder.

[0036] like Figure 2 As shown, the target distance adjustable lidar calibration system may include a host computer, calibration fixture 1, guide rail 2, target fixture 3, radar fixture 4, rangefinder 5, and camera 6.

[0037] In one embodiment, before testing the lidar to be calibrated, the host computer can control the target fixture to move to the maximum calibration distance, control the lidar to be calibrated to emit a laser signal, control the camera to acquire target images, determine whether the target image includes a light spot area, and if not, control the lidar fixture to rotate in the horizontal and / or vertical directions until the acquired target image includes the light spot area, so as to ensure that the lidar to be calibrated can be aligned with the target without manual adjustment of the lidar to be calibrated, thereby improving the automation and efficiency of calibration.

[0038] In another embodiment, before testing the lidar to be calibrated, the host computer can also control the target fixture to move to the zero position on the lidar fixture to avoid differences between different target fixtures, eliminate calibration errors caused by fixture differences, and improve the accuracy of lidar calibration.

[0039] In this embodiment, one or more calibration distances can be pre-configured. When using a target with the same reflectivity for calibration, the host computer controls the target fixture to slide along the guide rail and receives the distance measured by the rangefinder. This distance is the distance from the target on the target fixture to the lidar to be calibrated.

[0040] S302. When the distance is equal to the preset calibration distance, control the target fixture to stop moving.

[0041] When the distance equals each preset calibration distance, the target fixture is controlled to stop moving. For example, when the host computer determines that the distance equals the calibration distance, it stops outputting current to the motor of the target fixture or stops outputting excitation signal. The motor stops working, and the target fixture stops moving, so that the distance from the target to the lidar equals the calibration distance.

[0042] S303: Control the lidar to be calibrated to measure the distance to the target and obtain the ranging data; The host computer can control the lidar to be calibrated to measure the distance to the target and obtain the distance measurement data, and receive the distance measurement data from the lidar to be calibrated.

[0043] S304. Receive the ranging data of the lidar to be calibrated, and store the ranging data and calibration distance.

[0044] The host computer communicates with the lidar to be calibrated, can receive the ranging data of the lidar to be calibrated, and store the ranging data and calibration distance, thus completing the data collection required for calibrating the lidar to be calibrated when the target with the same reflectivity is at different calibration distances.

[0045] When it is necessary to switch to a target with a different reflectivity, the host computer receives the instruction to switch targets and controls the target fixture to rotate to switch to the target with the target reflectivity. After the target fixture is brought to zero, the above process is repeated to complete the data collection required for the calibration of the lidar to be calibrated at different calibration distances using a target with another reflectivity.

[0046] It should be noted that, for the method embodiment, since it is basically similar to the embodiment of the target-distance adjustable lidar calibration system, the description is relatively simple. For relevant details, please refer to the description of the target-distance adjustable lidar calibration system embodiment.

[0047] The lidar calibration method provided in this embodiment of the invention is applied to the target distance adjustable lidar calibration system provided in this embodiment of the invention, so that the lidar calibration method has corresponding beneficial effects.

[0048] It should be understood that although the steps in the flowcharts of the various embodiments of the present invention are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the various embodiments may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.

[0049] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0050] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

[0052] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A laser radar calibration system with adjustable target distance, characterized in that, include: A calibration fixture and guide rails located outside the calibration fixture; A target fixture is used to install targets with different reflectivities. The target fixture is slidably mounted on the guide rail and the target with different reflectivities can be switched by a rotation mechanism. The radar fixture and rangefinder are set on the calibration fixture, and the rangefinder is used to measure the distance from the target to the lidar to be calibrated installed on the radar fixture. The host computer communicates with the rangefinder, the target fixture, and the laser radar to be calibrated, which is mounted on the radar fixture. The host computer is used for: The target fixture is controlled to slide along the guide rail and the distance measured by the rangefinder is received. When the distance equals the preset calibration distance, the target tooling table is controlled to stop moving; The laser radar to be calibrated is controlled to measure the distance to the target, and the ranging data is obtained; Receive the ranging data of the lidar to be calibrated, and store the ranging data and the calibration distance.

2. The system according to claim 1, characterized in that, It also includes a camera mounted on the calibration fixture, the camera being connected to the host computer; The host computer is also used for: Control the target fixture to move to the maximum calibration distance, and control the lidar to be calibrated to emit a laser signal; Control the camera to acquire target images of the target; Determine whether the target image includes a spot area; If not, control the radar fixture to rotate in the horizontal and / or vertical directions until the acquired target image includes the spot area.

3. The system according to claim 1, characterized in that, The host computer is also used for: Control the target fixture to slide towards the radar fixture to the zero position.

4. The system according to claim 1, characterized in that, The host computer is also used for: Upon receiving a target switching instruction, the rotation mechanism of the target fixture is controlled to drive the target fixture to rotate in order to switch to the target with the target reflectivity.

5. The system according to claim 1, characterized in that, The sliding distance of the target tooling table on the guide rail is 10 to 50,000 mm.

6. The system according to claim 1, characterized in that, The target mounted on the target tooling table has a width of 10-2000mm and a height of 30-2000mm.

7. The system according to claim 1, characterized in that, The radar fixture has an elevation angle adjustment range of -20° to 20° and a horizontal rotation angle of 0° to 360°.

8. A lidar calibration method, characterized in that, The laser radar calibration method, applied to the target-distance adjustable laser radar calibration system according to any one of claims 1-7, comprises: The target fixture is controlled to slide along the guide rail and the distance measured by the rangefinder is received. When the distance equals the preset calibration distance, the target tooling table is controlled to stop moving; The laser radar to be calibrated is controlled to measure the distance to the target, and the ranging data is obtained; Receive the ranging data of the lidar to be calibrated, and store the ranging data and the calibration distance.

9. The method according to claim 8, characterized in that, Before controlling the target fixture to slide along the guide rail and receiving the distance measured by the rangefinder, the method further includes: Control the target fixture to move to the maximum calibration distance, and control the lidar to be calibrated to emit a laser signal; Control the camera to acquire target images of the target; Determine whether the target image includes a spot area; If not, control the radar fixture to rotate in the horizontal and / or vertical directions until the acquired target image includes the spot area.

10. The method according to claim 8, characterized in that, Also includes: Upon receiving a target switching instruction, the rotating mechanism of the target fixture is controlled to drive the target fixture to rotate in order to switch to the target with the target reflectivity.

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