Method for testing precision of vehicle positioning system in known environment based on repetitive experiment

Abstract

The invention belongs to the technical field of autonomous positioning of ground mobile platforms, and particularly relates to a method for testing the precision of a vehicle positioning system in a known environment based on a repetitive experiment, which comprises the following steps of: selecting a series of check points in an environment map, and determining a reference pose on each check point in a first round of experiment; in the subsequent repetitive experiment of each round, the vehicle is controlled to stop at each check point as much as possible in the reference pose, the change of the actual pose of each round relative to the reference pose of the first round is measured, the change of the estimated pose of the positioning system of each round relative to the estimated pose of the positioning system of the first round is calculated, and the difference between the two is compared to determine the position of the vehicle. And the positioning error of the vehicle positioning system in the known environment can be counted.

Description

Technical Field

[0001] The invention belongs to the technical field of autonomous positioning of ground mobile platforms, and in particular relates to a method for testing the accuracy of a vehicle positioning system in a known environment based on repeatable experiments. Background Art

[0002] When a vehicle is working in a relatively fixed environment, repeatable positioning accuracy is a very important performance and the basis for expanding other functions. The existing vehicle positioning system accuracy test methods in known environments can be divided into two categories in principle: one is to measure and calculate the actual position of the vehicle in the environment map by deploying auxiliary equipment such as ultra-wideband base stations or reflectors, and then compare it with the estimated position of the positioning system to calculate the positioning error; the other is to use the autonomous navigation system to control the vehicle to reach different target points in the environment map, and then measure the difference between the actual position and the target position at each stop, so as to calculate the positioning error. From the specific position measurement method, it can be further divided into image processing method and manual measurement method.

[0003] The method of testing the positioning accuracy by placing auxiliary equipment in the environment has high cost and computational complexity; the method of testing the positioning accuracy by controlling the vehicle to reach the target point through the autonomous navigation system cannot eliminate the errors caused by the autonomous navigation control itself. As for the specific posture measurement method, the image processing method has higher accuracy, but it is difficult to deploy because it needs to configure at least one visual integration subsystem in the environment; the manual measurement method has strong operability, but it is often interfered by human factors and has large errors. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The technical problem to be solved by the present invention is: how to provide a method for testing the accuracy of a vehicle positioning system in a known environment based on repeatable experiments.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the present invention provides a method for testing the accuracy of a vehicle positioning system in a known environment based on a repetitive experiment. The specific steps of the method are as follows:

[0008] Step 1: A laser rangefinder is fixedly installed on the top of the vehicle, and the direction of its laser emission is required to be consistent with the direction of the vehicle's movement.

[0009] Step 2: Select a series of checkpoints in different areas of the working environment, and each checkpoint must be surrounded by walls as reference objects for measuring posture.

[0010] Step 3: In the first round of experiments, the vehicle is controlled to stop at each checkpoint in turn, and the laser rangefinder on the roof is required to point vertically to the wall; the specific position of the center of the outer left front wheel of the vehicle touching the ground is marked to represent the position of the vehicle at this time, such as Figure 1 As shown; the marked pose is used as the reference pose for the repetitive experiment, and the estimated pose given by the vehicle positioning system at this time is recorded.

[0011] Step 4: In the next few rounds of repeated experiments, control the vehicle to stop at each checkpoint as much as possible with the reference posture, and record the estimated posture given by the vehicle positioning system;

[0012] Use a tape measure to measure the longitudinal and lateral displacement of the actual position of the center of contact of the outer left front wheel of the vehicle relative to the marked position in the first wheel, such as Figure 2 As shown; the distance from the laser emission point to the projection point on the wall in each round of experiments was measured with a laser rangefinder on the roof, and the horizontal distance between the projection point on the wall of each round of experiments and the projection point on the wall in the first round was measured with a tape measure;

[0013] Table 1 shows the data records required for all measured and calculated values, taking the first and second rounds of experiments at the first checkpoint as an example.

[0014] Table 1

[0015]

[0016] Step 5, using the measurement results of each checkpoint in each round of repeated experiments, calculate the angle of the vehicle's actual heading relative to the reference heading, that is, the direction pointing vertically to the wall, as Figure 3 As shown;

[0017] The rectangular coordinate system is constructed with the projection point LP1 of the laser rangefinder on the wall in the first round of experiments as the origin. Figure 3 The meanings of the various points, measured values, and calculated values ​​are listed in Table 2. From the geometric relationship in the triangle, we can see that:

[0018]

[0019] in, The heading angle difference between the first and second rounds of experiments;

[0020] d 12 : The distance of the projection points in the y direction in the first and second rounds of experiments;

[0021] The distance of the checkpoints in the y direction for the first and second rounds of experiments;

[0022] r1: The distance from the laser beam emission point to the projection point in the first round of experiments

[0023] The distances of the checkpoints in the x direction for the first and second rounds of experiments;

[0024] d 12 、r1、 and All can be obtained through measurement;

[0025] Table 2

[0026]

[0027] Step 6: Compare the measured displacement of the left front wheel outer contact center position relative to the first round reference position in each round of repetitive experiments with the estimated displacement of the positioning system, and compare the measured turning angle of the vehicle heading relative to the first round reference heading in each round of repetitive experiments with the estimated turning angle of the positioning system, so as to statistically calculate the error of the vehicle positioning system in a known environment based on repetitive experiments.

[0028] Tables 3 to 5 show the data records and calculations required for three rounds of repetitive experiments with six checkpoints. The calculation formulas for the longitudinal positioning error, lateral positioning error, and heading positioning error for each round of repetitive experiments are as follows:

[0029]

[0030] Table 3

[0031]

[0032] Table 4

[0033]

[0034]

[0035] Table 5

[0036]

[0037] (III) Beneficial effects

[0038] Based on the above analysis, in order to test the accuracy of the vehicle positioning system in a known environment with lower cost, easier operation and higher accuracy, the present invention proposes a method based on repeatable experiments, in which a series of checkpoints are selected in the environmental map and the reference posture at each checkpoint is determined in the first round of experiments. In each subsequent round of repeatable experiments, the vehicle is controlled to stop at each checkpoint with the reference posture as much as possible, and the change of the actual posture of each round relative to the reference posture of the first round is measured. The change of the estimated posture of the positioning system of each round relative to the estimated posture of the positioning system in the first round is calculated. By comparing the difference between the above two, the positioning error of the vehicle positioning system in the known environment can be statistically calculated.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. A vehicle positioning system accuracy test method based on repeatable experiments in a known environment is proposed, which has low cost, easy operation and high accuracy;

[0041] 2. Select the wall in the environment as the reference for measuring the position of each checkpoint. Its position is fixed and known, and no other auxiliary equipment is needed. The layout difficulty and calculation complexity are low.

[0042] 3. The reference headings are all perpendicular to the wall, so the heading angle difference can be easily and accurately derived and calculated based on the geometric relationship using the laser rangefinder on the roof;

[0043] 4. By conducting repeated experiments to statistically analyze positioning errors, we can reduce the uncertainty interference from the environment and sensors, and evaluate the repeatability and consistency of the vehicle positioning system in a known environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of marking the center position of the left front wheel's outer side touching the ground at the check point of the first round of experiments according to the present invention.

[0045] Figure 2 It is a schematic diagram of measuring the displacement of the actual position of the vehicle relative to the reference position of the first wheel in a repetitive experiment according to the present invention.

[0046] Figure 3 This is a schematic diagram of calculating the heading angle difference using the measurement results of the laser rangefinder on the top of the vehicle according to the present invention. DETAILED DESCRIPTION

[0047] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0048] In order to solve the above technical problems, the present invention provides a method for testing the accuracy of a vehicle positioning system in a known environment based on a repetitive experiment. The specific steps of the method are as follows:

[0049] Step 1: A laser rangefinder is fixedly installed on the top of the vehicle, and the direction of its laser emission is required to be consistent with the direction of the vehicle's movement.

[0050] Step 2: Select a series of checkpoints in different areas of the working environment, and each checkpoint must be surrounded by walls as reference objects for measuring posture.

[0051] Step 3: In the first round of experiments, the vehicle is controlled to stop at each checkpoint in turn, and the laser rangefinder on the roof is required to point vertically to the wall; the specific position of the center of the outer left front wheel of the vehicle touching the ground is marked to represent the position of the vehicle at this time, such as Figure 1 As shown; the marked pose is used as the reference pose for the repetitive experiment, and the estimated pose given by the vehicle positioning system at this time is recorded.

[0052] Step 4: In the next few rounds of repeated experiments, control the vehicle to stop at each checkpoint as much as possible with the reference posture, and record the estimated posture given by the vehicle positioning system;

[0053] Use a tape measure to measure the longitudinal and lateral displacement of the actual position of the center of contact of the outer left front wheel of the vehicle relative to the marked position in the first wheel, such as Figure 2 As shown; the distance from the laser emission point to the projection point on the wall in each round of experiments was measured with a laser rangefinder on the roof, and the horizontal distance between the projection point on the wall of each round of experiments and the projection point on the wall in the first round was measured with a tape measure;

[0054] Table 1 shows the data records required for all measured and calculated values, taking the first and second rounds of experiments at the first checkpoint as an example.

[0055] Table 1

[0056]

[0057] Step 5, using the measurement results of each checkpoint in each round of repeated experiments, calculate the angle of the vehicle's actual heading relative to the reference heading, that is, the direction pointing vertically to the wall, as Figure 3 As shown;

[0058] The rectangular coordinate system is constructed with the projection point LP1 of the laser rangefinder on the wall in the first round of experiments as the origin. Figure 3 The meanings of the various points, measured values, and calculated values ​​are listed in Table 2. From the geometric relationship in the triangle, we can see that:

[0059]

[0060] in, The heading angle difference between the first and second rounds of experiments;

[0061] d 12 : The distance of the projection points in the y direction in the first and second rounds of experiments;

[0062] The distance of the checkpoints in the y direction for the first and second rounds of experiments;

[0063] r1: The distance from the laser beam emission point to the projection point in the first round of experiments

[0064] The distances of the checkpoints in the x direction for the first and second rounds of experiments;

[0065] d 12 、r1、 and All can be obtained through measurement;

[0066] Table 2

[0067]

[0068] Step 6: Compare the measured displacement of the left front wheel outer contact center position relative to the first round reference position in each round of repetitive experiments with the estimated displacement of the positioning system, and compare the measured turning angle of the vehicle heading relative to the first round reference heading in each round of repetitive experiments with the estimated turning angle of the positioning system, so as to statistically calculate the error of the vehicle positioning system in a known environment based on repetitive experiments.

[0069] Tables 3 to 5 show the data records and calculations required for three rounds of repetitive experiments with six checkpoints. The calculation formulas for the longitudinal positioning error, lateral positioning error, and heading positioning error for each round of repetitive experiments are as follows:

[0070]

[0071]

[0072] Table 3

[0073]

[0074] Table 4

[0075]

[0076] Table 5

[0077]

[0078]

[0079] The alternative contents of the solution of the present invention include:

[0080] 1. Using objects artificially placed in the environment, such as shelves and wooden boxes, to replace walls as reference objects for measuring heading is considered to be the same solution;

[0081] 2. Using other wheels, such as the left rear wheel, the right front wheel, etc., instead of the left front wheel to mark the vehicle position is considered to be the same solution;

[0082] 3. Changing the installation angle of the laser rangefinder on the top of the vehicle, such as changing from being consistent with the vehicle's forward direction to being perpendicular to the forward direction, and changing the angle between the heading of the reference posture and the wall, such as changing from 90° to 0°, are considered to be the same solution.

[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment, characterized in that: The specific steps of the method are as follows: Step 1: A laser rangefinder is fixedly installed on the top of the vehicle, and the direction of its laser emission is required to be consistent with the direction of the vehicle's movement. Step 2: Select a series of checkpoints in different areas of the working environment, and each checkpoint must be surrounded by walls as reference objects for measuring posture. Step 3. In the first round of experiments, the vehicle is controlled to stop at each checkpoint in turn, and the laser rangefinder on the roof is required to point vertically to the wall; the specific position of the center of the outer left front wheel of the vehicle touching the ground is marked to represent the position of the vehicle at this time; the marked posture is used as the reference posture for repeated experiments, and the estimated posture given by the vehicle positioning system at this time is recorded. Step 4: In the next few rounds of repeated experiments, control the vehicle to stop at each checkpoint as much as possible with the reference posture, and record the estimated posture given by the vehicle positioning system; Measure the longitudinal and lateral displacements of the actual position of the center of contact with the ground by the outer left front wheel of the vehicle relative to the marked position in the first round; use the laser rangefinder on the roof to measure the distance from the laser emission point to the projection point on the wall in each round of the experiment, and measure the horizontal distance between the projection point on the wall of the laser beam in each round of the experiment and the projection point on the wall in the first round; Step 5, using the measurement results of each checkpoint in each round of repeated experiments, calculate the turning angle of the vehicle's actual heading relative to the reference heading, that is, the direction pointing vertically to the wall; The rectangular coordinate system is constructed with the projection point LP1 of the laser rangefinder on the wall in the first round of experiments as the origin. From the geometric relationship in the triangle, we can know that: in, The heading angle difference between the first and second rounds of experiments; d 12 : The distance of the projection points in the y direction in the first and second rounds of experiments; The distance of the checkpoints in the y direction for the first and second rounds of experiments; r1: The distance from the laser beam emission point to the projection point in the first round of experiments The distances of the checkpoints in the x direction for the first and second rounds of experiments; Step 6: Compare the measured displacement of the left front wheel outer contact center position relative to the first round reference position in each round of repetitive experiments with the estimated displacement of the positioning system, and compare the measured turning angle of the vehicle heading relative to the first round reference heading in each round of repetitive experiments with the estimated turning angle of the positioning system, so as to statistically calculate the error of the vehicle positioning system in a known environment based on repetitive experiments.

2. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 1, characterized in that: In step 4, Table 1 shows the data records required for all measured values ​​and calculated values ​​in the first and second rounds of experiments at the first checkpoint; Table 1 3. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 2, characterized in that: In step 5, d 12 、r1、 and All can be obtained through measurement.

4. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 3, characterized in that: In step 6, Tables 3 to 5 are provided to show the data records and calculations required in 6 checkpoints and 3 rounds of repeated experiments; Table 3 Table 4 Table 5 5. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 4, characterized in that: In step 6, the calculation formula for the longitudinal positioning error of each round of repeatability experiment is: Where i=1,2,...,6,j=2,3(2).

6. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 5, characterized in that: In step 6, the calculation formula for the lateral positioning error of each round of repeatability experiment is: Where i=1,2,...,6,j=2,3(3).

7. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 6, characterized in that: In step 6, the calculation formula for the heading positioning error of each round of repetitive experiments is: Where i=1,2,...,6,j=2,3(4).

8. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 1, characterized in that: In step 4, a tape measure is used to measure the longitudinal displacement and lateral displacement of the actual position of the ground contact center of the outer side of the left front wheel of the vehicle relative to the marked position in the first wheel.

9. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 1, characterized in that: In step 4, a tape measure is used to measure the horizontal distance between the projection point on the wall of each round of experimental laser beam and the projection point on the wall of the first round.

10. The method for testing the accuracy of a vehicle positioning system in a known environment based on a repeatable experiment as claimed in claim 1, characterized in that: The method belongs to the technical field of autonomous positioning of ground mobile platforms.

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