Accuracy Testing Method for Vehicle Positioning Systems in Known Environments Based on Repeatable Experiments

Abstract

This invention belongs to the field of autonomous positioning technology for ground mobile platforms, specifically relating to a method for testing the accuracy of a vehicle positioning system in a known environment based on repeatable experiments. The invention proposes a method based on repeatable experiments, selecting a series of checkpoints on an environmental map and determining the reference pose at each checkpoint in the first round of experiments. In subsequent rounds of repeatable experiments, the vehicle is controlled to stop at each checkpoint as close as possible to the reference pose. The change in the actual pose in each round relative to the reference pose in the first round is measured, and the change in the estimated pose of the positioning system in each round relative to the estimated pose in the first round is calculated. By comparing the differences between these two, the positioning error of the vehicle positioning system in a known environment can be statistically determined.

Description

Technical Field

[0001] This invention belongs to the field of autonomous positioning technology for ground mobile platforms, specifically relating to a method for testing the accuracy of vehicle positioning systems in known environments based on repeatable experiments. Background Technology

[0002] When a vehicle operates in a relatively fixed environment, repeatability accuracy is a crucial performance characteristic and the foundation for its extended functionality. Existing methods for testing the accuracy of vehicle positioning systems in known environments can be broadly categorized into two types based on their principles: one involves deploying auxiliary equipment such as ultra-wideband base stations or reflectors to measure and calculate the vehicle's actual pose on an environmental map, then comparing it with the estimated pose of the positioning system to statistically analyze the positioning error; the other utilizes an autonomous navigation system to control the vehicle to different target points on the environmental map, then measures the difference between the actual pose and the target pose at each stop to statistically analyze the positioning error. In terms of specific pose measurement methods, these can be further divided into image processing methods and manual measurement methods.

[0003] Testing positioning accuracy by deploying auxiliary equipment in the environment is costly and computationally complex. Testing positioning accuracy by controlling a vehicle to the target point using an autonomous navigation system cannot eliminate errors inherent in the autonomous navigation control itself. For specific pose measurement methods, image processing offers high accuracy, but requires at least one vision integration subsystem in the environment, presenting significant deployment challenges. Manual measurement methods are highly operable, but are susceptible to human error and contain substantial inaccuracies. Summary of the Invention

[0004] (a) Technical problems to be solved

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

[0006] (II) Technical Solution

[0007] To address the aforementioned technical problems, this invention provides a method for testing the accuracy of a vehicle positioning system under known conditions based on repeatability experiments. The specific steps of the method are as follows:

[0008] Step 1: Fix a laser rangefinder on the top of the vehicle, ensuring that the direction of its laser emission is consistent with the direction of the vehicle's movement.

[0009] Step 2: Select a series of checkpoints in different areas of the work environment, requiring that each checkpoint be surrounded by a wall as a reference for measuring the pose.

[0010] Step 3: In the first round of experiments, control the vehicle to stop at each checkpoint in sequence, ensuring that the laser rangefinder on the roof is always pointed perpendicularly to the wall; mark the exact position of the center of contact between the outer left front wheel and the ground to represent the vehicle's current position, such as... Figure 1 As shown, the marked pose is used as the reference pose for repeatable experiments, and the estimated pose given by the vehicle positioning system at this time is recorded.

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

[0012] Use a measuring tape to measure the longitudinal and lateral displacements of the actual position of the outer center of the left front wheel relative to the marked position on the first wheel, such as... Figure 2 As shown; use a laser rangefinder on the roof of the vehicle to measure the distance from the laser emission point to the projection point on the wall in each round of the experiment, and use a measuring tape to 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;

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

[0014] Table 1

[0015]

[0016] Step 5: Calculate the vehicle's actual heading relative to the reference heading, i.e., the angle of rotation in the direction perpendicular to the wall, using the measurement results from each checkpoint in each round of repeatable testing. Figure 3 As shown;

[0017] Construct a rectangular coordinate system 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 each point, measured value, and calculated value are listed in Table 2. From the geometric relationships within the triangle, we can see that:

[0018]

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

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

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

[0024] d 12 r1 and All of these 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 reference position of the first round in each round of repeatable experiments with the estimated displacement of the positioning system; compare the measured turning angle of the vehicle heading relative to the reference heading of the first round in each round of repeatable experiments with the estimated turning angle of the positioning system, thereby statistically analyzing the error of the vehicle positioning system under known conditions based on repeatable experiments.

[0028] Tables 3-5 show the data recording and calculations required for a 6-checkpoint, 3-round repeatability test. The formulas for calculating the longitudinal positioning error, lateral positioning error, and heading positioning error for each round of repeatability test 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 a vehicle positioning system in a known environment with lower cost, easier operation, and higher accuracy, this invention proposes a method based on repeatable experiments. A series of checkpoints are selected in the environment map, and the reference pose 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 as close as possible to the reference pose. The change in the actual pose of each round relative to the reference pose of the first round is measured, and the change in the estimated pose of the positioning system in each round relative to the estimated pose of the positioning system in the first round is calculated. By comparing the difference between the two, the positioning error of the vehicle positioning system in the known environment can be statistically determined.

[0039] Compared with the prior art, the beneficial effects of this invention are as follows:

[0040] 1. A method for testing the accuracy of vehicle positioning systems under known environments based on repeatable experiments is proposed, which has low cost, easy operation and high accuracy;

[0041] 2. Select the wall in the environment as the reference object for measuring the pose of each check point. 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 geometric relationships using the laser rangefinder on the roof of the vehicle;

[0043] 4. By conducting repeatability experiments to statistically analyze positioning errors, we can reduce the interference from uncertainties in the environment and sensors, and evaluate the repeatability and consistency of the vehicle positioning system under known conditions. Attached Figure Description

[0044] Figure 1 This is a schematic diagram illustrating the marking of the center position of the outer left front wheel contacting the ground at the checkpoint in the first round of experiments, as described in this invention.

[0045] Figure 2 This is a schematic diagram illustrating the measurement of the actual position displacement of a vehicle relative to the reference position of the first wheel in a repeatable experiment, as described in this invention.

[0046] Figure 3 This is a schematic diagram illustrating the calculation of heading angle difference using the measurement results of a laser rangefinder on the top of a vehicle, as described in this invention. Detailed Implementation

[0047] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0048] To address the aforementioned technical problems, this invention provides a method for testing the accuracy of a vehicle positioning system under known conditions based on repeatability experiments. The specific steps of the method are as follows:

[0049] Step 1: Fix a laser rangefinder on the top of the vehicle, ensuring that the direction of its laser emission is consistent with the direction of the vehicle's movement.

[0050] Step 2: Select a series of checkpoints in different areas of the work environment, requiring that each checkpoint be surrounded by a wall as a reference for measuring the pose.

[0051] Step 3: In the first round of experiments, control the vehicle to stop at each checkpoint in sequence, ensuring that the laser rangefinder on the roof is always pointed perpendicularly to the wall; mark the exact position of the center of contact between the outer left front wheel and the ground to represent the vehicle's current position, such as... Figure 1 As shown, the marked pose is used as the reference pose for repeatable experiments, and the estimated pose given by the vehicle positioning system at this time is recorded.

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

[0053] Use a measuring tape to measure the longitudinal and lateral displacements of the actual position of the outer center of the left front wheel relative to the marked position on the first wheel, such as... Figure 2 As shown; use a laser rangefinder on the roof of the vehicle to measure the distance from the laser emission point to the projection point on the wall in each round of the experiment, and use a measuring tape to 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;

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

[0055] Table 1

[0056]

[0057] Step 5: Calculate the vehicle's actual heading relative to the reference heading, i.e., the angle of rotation in the direction perpendicular to the wall, using the measurement results from each checkpoint in each round of repeatable testing. Figure 3 As shown;

[0058] Construct a rectangular coordinate system 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 each point, measured value, and calculated value are listed in Table 2. From the geometric relationships within the triangle, we can understand that:

[0059]

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

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

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

[0065] d 12 r1 and All of these 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 reference position of the first round in each round of repeatable experiments with the estimated displacement of the positioning system; compare the measured turning angle of the vehicle heading relative to the reference heading of the first round in each round of repeatable experiments with the estimated turning angle of the positioning system, thereby statistically analyzing the error of the vehicle positioning system under known conditions based on repeatable experiments.

[0069] Tables 3-5 show the data recording and calculations required for a 6-checkpoint, 3-round repeatability test. The formulas for calculating the longitudinal positioning error, lateral positioning error, and heading positioning error for each round of repeatability test are as follows:

[0070]

[0071]

[0072] Table 3

[0073]

[0074] Table 4

[0075]

[0076] Table 5

[0077]

[0078]

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

[0080] 1. Using objects placed in the environment by people, such as shelves or wooden boxes, to replace walls as reference points for measuring heading is considered to be the same approach;

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

[0082] 3. Changing the installation angle of the laser rangefinder on the vehicle roof, such as changing it from being aligned with the vehicle's direction of travel to being perpendicular to the direction of travel, and changing the angle between the reference pose's heading and the wall, such as changing it from 90° to 0°, are considered the same solution.

[0083] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for testing the accuracy of a vehicle positioning system under known conditions based on repeatability experiments, characterized in that, The specific steps of the method are as follows: Step 1: Fix a laser rangefinder on the top of the vehicle, ensuring that the direction of its laser emission is consistent with the direction of the vehicle's movement; Step 2: Select a series of checkpoints in different areas of the work environment, requiring that each checkpoint be surrounded by a wall as a reference for measuring the pose; Step 3: In the first round of experiments, control the vehicle to stop at each checkpoint in sequence, requiring the laser rangefinder on the roof to be pointed vertically at the wall; mark the specific position of the center of the outer side of the left front wheel touching the ground to represent the position of the vehicle at this time; use the marked pose as the reference pose for the repeatable experiment, and record the estimated pose given by the vehicle positioning system at this time. Step 4: In the next few rounds of repetitive experiments, control the vehicle to stop at each checkpoint with a reference pose, and record the estimated pose given by the vehicle positioning system. Measure the longitudinal and lateral displacements of the actual position of the outer side of the vehicle's left front wheel relative to the marked position in the first round; use a 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: Calculate the vehicle's actual heading relative to the reference heading, i.e., the angle of rotation in the direction perpendicular to the wall, using the measurement results of each checkpoint in each round of repeatable experiments. The projection point of the laser rangefinder on the wall in the first round of experiments Construct a rectangular coordinate system with the origin. From the geometric relationships within the triangle, we can see that: （1） in, The difference in heading angle between the first and second rounds of experiments; The distance between the projection points in the y-direction in the first and second rounds of experiments; The distance in the y-direction between the checkpoints in the first and second rounds of experiments; The distance from the laser beam emission point to the projection point in the first round of experiments. The distance between the checkpoints in the first and second rounds of experiments in the x-direction; Step 6: Compare the measured displacement of the left front wheel outer contact center position relative to the reference position of the first round in each round of repeatable experiments with the estimated displacement of the positioning system; compare the measured turning angle of the vehicle heading relative to the reference heading of the first round in each round of repeatable experiments with the estimated turning angle of the positioning system, thereby statistically analyzing the error of the vehicle positioning system under known conditions based on repeatable experiments.

2. The method for testing the accuracy of a vehicle positioning system under known conditions based on repeatability experiments as described in claim 1, characterized in that, In step 4, Table 1 shows the data records required for all measured 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 under known conditions based on repeatability experiments as described in claim 2, characterized in that, In step 5 , , and All of these can be obtained through measurement.

4. The method for testing the accuracy of a vehicle positioning system under known conditions based on repeatable experiments as described in claim 3, characterized in that, In step 6, Tables 3-5 are provided to show the data recording and calculations to be performed in 6 checkpoints and 3 rounds of repeatable experiments; Table 3 Table 4 Table 5 。 5. The method for testing the accuracy of a vehicle positioning system under a known environment based on repeatable experiments as described in claim 4, characterized in that, In step 6, the formula for calculating the longitudinal positioning error for each round of repeatable experiments is as follows: （2）。 6. The method for testing the accuracy of a vehicle positioning system under known conditions based on repeatability experiments as described in claim 5, characterized in that, In step 6, the formula for calculating the lateral positioning error for each round of repeatable experiments is as follows: （3）。 7. The method for testing the accuracy of a vehicle positioning system under known conditions based on repeatable experiments as described in claim 6, characterized in that, In step 6, the formula for calculating the heading and positioning error for each round of repeatable experiments is as follows: （4）。 8. The method for testing the accuracy of a vehicle positioning system under known conditions based on repeatability experiments as described in claim 7, characterized in that, In step 4, a measuring tape is used to measure the actual longitudinal and lateral displacements of the center of contact with the ground on 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 under known conditions based on repeatability experiments as described in claim 1, characterized in that, In step 4, the horizontal distance between the projection point on the wall of each round of experimental laser beams and the projection point on the wall of the first round is measured with a tape measure.

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

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