Commercial vehicle transfer attitude correction method based on tire detection

Abstract

The invention discloses a commercial vehicle docking posture correction method based on tire detection, and belongs to the unmanned driving field in the automatic control field. According to the method, when a transfer AGV carries out vehicle taking operation on a target commercial vehicle, original scanning data of four single-line laser radars in the vehicle are obtained, and point cloud information, scanned by the single-line laser radars, of four tires of the target commercial vehicle is obtained through preprocessing; the position and the orientation of the target commercial vehicle in the transfer AGV are calculated through the single-line laser radars installed at the four corners of the interior of the transfer AGV, the orientation and the position of the transfer AGV are corrected in a small range so that the orientation and the position of the transfer AGV can be consistent with the target commercial vehicle, the safety and the accuracy of follow-up vehicle taking operation are guaranteed, and the stability of the operation process of the transfer AGV system is improved. According to the method, the position and direction of the target commercial vehicle are sensed through the single-line laser radar, the transfer AGV docking offset correction value is calculated, and the method has the advantages of being high in deviation correction precision, high in operation efficiency and low in implementation difficulty.

Description

Technical Field

[0001] This invention relates to a method for correcting the attitude of a commercial vehicle during transport based on tire detection, which belongs to the field of unmanned driving within the field of automatic control. Background Technology

[0002] With strong support from China's economic policies and rapid development of manufacturing technology, China's automobile export trade has experienced booming growth, making my country the world's largest automobile exporter. The ever-increasing demand for automobiles poses significant challenges to the traditional automobile terminal operation model in terms of throughput and storage capacity.

[0003] Therefore, the Automated Guided Vehicle (AGV) system for vehicle transfer has emerged. This system consists of a port vehicle management system, a cloud-based AGV dispatching system, AGVs, and automated storage and retrieval systems. The port vehicle management system issues vehicle transfer orders, the cloud-based dispatching system plans the transfer route, and sends the orders to the individual AGV actuators. The AGVs then transfer the vehicles from the port's vehicle yard to the intelligent automated storage and retrieval system, completing the vehicle transfer.

[0004] The operational system based on the AGV (Automated Guided Vehicle) system for vehicle transfer has achieved intelligent and unmanned vehicle transfer at the port. Compared with traditional manual transfer, the number of operators has been reduced by more than 60%, and the turnover efficiency has been increased by more than 20%, alleviating the pressure on vehicle transfer at the port.

[0005] In the AGV system for vehicle transfer, the cloud-based scheduling system plans the routes, and the AGVs track these routes to perform vehicle retrieval and placement operations in the port's vehicle yard. Because the actual placement and orientation of the vehicles may differ from the records in the cloud system, when the AGVs retrieve vehicles with these errors, they amplify these errors. Ultimately, after multiple retrieval and placement operations, the error between the actual placement and orientation of the vehicles and the cloud records exceeds a threshold. At this point, the cloud-planned AGV operation routes will no longer accurately guide the AGVs in their retrieval and placement operations, posing a challenge to the stability of the AGV operations and impacting the overall operational efficiency of the vehicle transfer system. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a method for determining the vehicle's position and orientation based on the position and orientation of the vehicle's tires during vehicle retrieval operations, and thereby correcting the retrieval posture of the transfer AGV. This method has advantages such as high path correction accuracy, high correction efficiency, and ease of implementation.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] This invention discloses a method for correcting the transport posture of a commercial vehicle based on tire detection, comprising the following steps:

[0009] Step 1: When the AGV is locating the target vehicle, acquire the original scanning data of the four single-line lidars installed in the vehicle and perform lidar point cloud data preprocessing.

[0010] Step 2: Based on the preprocessed laser point cloud data obtained in Step 1, obtain the point cloud sets of the left front, left rear, right front, and right rear tires of the target vehicle, and further extract the geometric center coordinates of the above four tires.

[0011] Step 3: Based on the coordinates of the geometric center points of the four tires obtained in Step 2, obtain the coordinates of the vehicle's geometric center point.

[0012] Step 4: Based on the geometric center points of the left and right front tires obtained in Step 2, determine the coordinates of the center point of the front of the vehicle.

[0013] Step 5: Based on the vehicle geometric center point coordinates in Step 3 and the vehicle front center point coordinates in Step 4, obtain the horizontal offset angle of the target vehicle relative to the transfer AGV.

[0014] Step 6: Process the horizontal offset angle obtained in Step 5 to obtain the rotation direction and rotation angle of the transfer AGV;

[0015] Step 7: Process the coordinates of the vehicle's geometric center point obtained in Step 3 and the horizontal offset angle of the target vehicle relative to the transfer AGV obtained in Step 5 to obtain the displacement correction amount for the longitudinal and lateral movements of the transfer AGV.

[0016] The specific implementation method of step one is as follows: when the transfer AGV is performing a vehicle retrieval operation on the target vehicle, the raw scanning data of the single-line LiDAR inside the vehicle (left front, right front, left rear, and right rear) is acquired. The raw scanning data of the single-line LiDAR is preprocessed to acquire the point cloud information of the left front, right front, left rear, and right rear tires of the target vehicle scanned by the single-line LiDAR. The point cloud set of the left front tire is recorded as L1, the point cloud set of the right front tire is recorded as L2, the point cloud set of the left rear tire is recorded as L3, and the point cloud set of the right rear tire is recorded as L4. The data preprocessing includes point cloud coordinate transformation and point cloud threshold filtering.

[0017] The specific implementation method of step two is as follows: The point cloud sets of the left front, right front, left rear, and right rear tires of the vehicle obtained in step one are processed to obtain the coordinate values ​​of the center points of the four tires. The center point of the left front tire is denoted as P1, the center point of the right front tire as P2, the center point of the left rear tire as P3, and the center point of the right rear tire as P4. The tire point cloud set L...i Its tire center coordinates (P) ix P iy It is calculated using the following formula:

[0018]

[0019] Where n is the point cloud set L i The number of laser points in the point cloud set L i Any point P inside j Its x-coordinate is The vertical axis is

[0020] The specific implementation method of step three is as follows: based on the coordinate values ​​of the center points of the left front, right front, left rear, and right rear tires obtained in step two (P... ix P iy Calculate the center point P of the target vehicle. 中心 (P Δx P Δy ):

[0021]

[0022] The specific implementation method of step four is to calculate the front center point P of the target vehicle based on the coordinate values ​​of the center points of the left and right front tires obtained in step two. 前中 :

[0023]

[0024] The specific implementation method of step five is as follows: based on the target vehicle center point P obtained in step three... 中心 The target vehicle's front center point P obtained in step four 前中 The horizontal offset angle θ of the target vehicle relative to the transfer AGV is obtained. Δ :

[0025]

[0026] The specific implementation method of step six is ​​as follows: based on θ obtained in step five... Δ The rotation direction and rotation angle θ of the transfer AGV are obtained. Δ If θ Δ If the angle is negative, the rotation direction is counterclockwise, and the rotation angle is equal to -θ. Δ If θ Δ If the angle is positive, the direction of rotation is clockwise, and the rotation angle is equal to θ. Δ The transfer AGV rotates to align its orientation with that of the target vehicle, thus completing the angle correction of the transfer AGV.

[0027] The specific implementation method of step seven is as follows: based on the horizontal offset angle θ of the target vehicle relative to the transfer AGV obtained in step five... Δ The center point P of the target vehicle obtained in step three 中心 (P Δx P Δy The longitudinal displacement correction L of the transfer AGV is obtained. Δ1 With lateral displacement correction L Δ2 :

[0028] L Δ1 =P Δx sinθ Δ +P Δy cosθ Δ ,L Δ2 =P Δx cosθ Δ -P Δy sinθ Δ

[0029] Taking the forward direction of the transfer AGV as the positive direction of longitudinal displacement and the right side of the transfer AGV as the positive direction of lateral displacement, let the longitudinal displacement L of the transfer AGV be... Δ1 Lateral displacement L Δ2 This ensures that the AGV being transported is aligned with the target vehicle in terms of orientation and geometric center, thus achieving the target correction.

[0030] Beneficial effects:

[0031] 1. The present invention discloses a method for correcting the docking posture of a commercial vehicle based on tire detection. By using single-line laser radar installed at the four corners inside the transfer AGV to identify the position and orientation of the four tires of the target commercial vehicle, the method calculates the orientation angle and longitudinal and lateral offset of the target commercial vehicle relative to the transfer AGV, and finely corrects the orientation and position of the transfer AGV to make it consistent with the target commercial vehicle, thereby ensuring the safety and accuracy of subsequent vehicle retrieval operations and improving the stability of the transfer AGV system operation process.

[0032] 2. This invention discloses a method for correcting the attitude of transporting commercial vehicles based on tire detection. It uses a single-line lidar to sense the position and orientation of the target commercial vehicle and calculates the correction amount for the transport AGV relative to the target commercial vehicle. This method offers high correction accuracy, high operational efficiency, and low implementation difficulty.

[0033] 3. The present invention discloses a method for correcting the attitude of a transport vehicle based on tire detection. It constructs a formula for calculating the offset of the target vehicle relative to the transport AGV based on the tire position and orientation. Based on this, it constructs formulas for calculating the correction amount of the orientation angle of the transport AGV and the correction amount in the longitudinal and transverse directions, so as to accurately and precisely complete the correction work of the transport AGV in picking up the target vehicle. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall process of a vehicle transport posture correction method based on tire detection proposed in this invention;

[0035] Figure 2 It is a simplified top view of the relative relationship between the transfer AGV and the target vehicle during the attitude correction process;

[0036] Figure 3 This is a simplified top-view diagram of the process by which the AGV (Automated Guided Vehicle) makes precise motion adjustments based on the position and posture of the target goods vehicle.

[0037] Among them: 1-Transfer AGV, 2.1-Left front single-line LiDAR, 2.2-Right front single-line LiDAR, 2.3-Left rear single-line LiDAR, 2.4-Right rear single-line LiDAR, 3-Carrying vehicle, 4.1-Left front tire scanning point cloud, 4.2-Right front tire scanning point cloud, 4.3-Left rear tire scanning point cloud, 4.4-Right rear tire scanning point cloud, 5.1-Left front tire center point, 5.2-Right front tire center point, 5.3-Left rear tire center point, 5.4-Right rear tire center point, 6-Target vehicle geometric center point, 7-Target vehicle front center point, 8-Target vehicle front orientation, 9-Transfer AGV correction angle, 10-Transfer AGV longitudinal correction distance, 11-Transfer AGV lateral correction distance. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0039] Implementation Method 1

[0040] like Figure 1 This embodiment discloses a vehicle docking posture correction method based on tire detection, which can correct the posture of vehicles with incorrect parking posture when the straddle-type dual-body AGV transfer vehicle is performing vehicle picking and placing operations. This ensures that the target vehicle can maintain the same position coordinates and orientation angle as recorded in the cloud after the transfer AGV is placed, thus guaranteeing the operational stability of the subsequent vehicle picking and placing process of the vehicle transfer system.

[0041] This embodiment is based on an AGV system for transporting finished vehicles, such as... Figure 2As shown, the system includes a transfer AGV 1 and four single-line LiDARs installed at the four corners inside the transfer AGV 1: left front single-line LiDAR 2.1, right front single-line LiDAR 2.2, left rear single-line LiDAR 2.3, and right rear single-line LiDAR 2.4. The transfer AGV 1 has a straddle-type double-body structure. During transfer operations, it can straddle the target vehicle, clamp the tires of the vehicle with mechanical grippers, and carry the vehicle for transfer. After reaching the target transfer location, it unloads the vehicle and exits the parking space to perform subsequent work processes.

[0042] like Figure 1 As shown in the figure, the specific implementation steps of the commercial vehicle transfer pose correction method based on tire detection disclosed in this embodiment are as follows:

[0043] S1. When the transfer AGV 1 is performing vehicle retrieval operations, a coordinate system is established with the geometric center point of the transfer AGV as the origin, the lateral movement direction of the AGV to the right as the positive X-axis direction, and the forward movement direction of the AGV as the positive Y-axis direction. The left front, right front, left rear, and right rear tires of the target vehicle 3 are scanned by the left front, right front, left rear, and right rear single-line laser point clouds, respectively, to obtain the original single-line laser point clouds. The original single-line laser point clouds are then filtered: a longitudinal filtering range of 50cm in front and behind and a lateral filtering range of 20cm inward are selected, and point clouds outside the filtering range are removed. Based on the installation position constraints of the single-line laser radars and the vehicle body, the filtered point clouds are subjected to coordinate transformation processing to obtain the scanned point clouds 4.1 (left front tire), 4.2 (right front tire), 4.3 (left rear tire), and 4.4 (right rear tire).

[0044] S2, based on the scanned point clouds 4.1 (outer side of the left front tire), 4.2 (outer side of the right front tire), 4.3 (outer side of the left rear tire), and 4.4 (outer side of the right rear tire) obtained in S1, is processed to obtain the center points 5.1 (outer side of the left front tire), 5.2 (outer side of the right front tire), 5.3 (outer side of the left rear tire), and 5.4 (outer side of the right rear tire) of the vehicle.

[0045]

[0046] Where n is the point cloud set L i The number of laser points in the point cloud set L i Any point P inside j Its x-coordinate is The vertical axis is Using centimeters as the unit, the center point coordinates of the single-line laser scan point cloud of the left front tire are (-479.7, 1336.3) for 5.1, (912.2, 1090.8) for 5.2, (-904.8, -1074.4) for 5.3, and (487.1, -1319.9) for 5.4.

[0047] S3, based on the center points 5.1, 5.2, 5.3, 5.4 of the single-line laser scanning point cloud of the left front tire, 5.4, obtained in S2, the coordinates (P) of the geometric center point 6 of the target vehicle are obtained. Δx P Δy ):

[0048]

[0049] The geometric center point of the target vehicle is located at (3.7, 8.2) centimeters.

[0050] S4, based on the coordinates 5.1 of the center point of the single-line laser scanning point cloud of the left front tire and 5.2 of the center point of the single-line laser scanning point cloud of the right front tire obtained in S2, the coordinates of the center point 7 of the front of the target vehicle are obtained (P). x前中 P y前中 ):

[0051]

[0052] The coordinates of the center point of the front end of the target vehicle are (216.3, 1213.6) in centimeters.

[0053] S5, based on the coordinates of the geometric center point 6 of the target vehicle obtained in S3 and the coordinates of the front center point 7 of the target vehicle obtained in S4, the orientation 8 of the target vehicle inside the transfer AGV is obtained:

[0054]

[0055] Where θ Δ The angle of orientation of the target vehicle inside the transfer AGV is calculated to be 10.1°.

[0056] S6, based on the orientation angle θ of the target vehicle inside the transfer AGV obtained from S5, if θ Δ If the angle is negative, the rotation direction is counterclockwise, and the rotation angle is equal to -θ. Δ If θ Δ If the angle is positive, the direction of rotation is clockwise, and the rotation angle is equal to θ. ΔThe transfer AGV enters rotation mode and rotates 10.1° clockwise, aligning the transfer AGV with the target vehicle's orientation, thus completing the AGV angle correction.

[0057] S7, based on the coordinates of the geometric center point 6 of the target vehicle obtained in S3 (P) Δx P Δy The longitudinal displacement correction L of the transfer AGV is obtained by comparing the orientation of the target vehicle inside the transfer AGV obtained from S5 with that of S5. Δ1 With lateral displacement correction L Δ2 :

[0058] L Δ1 =P Δx sinθ Δ +P Δy cosθ Δ ,L Δ2 =P Δx cosθ Δ -P Δy sinθ Δ

[0059] The longitudinal displacement correction L of the transfer AGV, measured in centimeters. Δ1 The lateral displacement correction value L of the transfer AGV is 8.2. Δ2 The value is 3.7. The transfer AGV enters the straight-line motion mode, moving forward 8.2 cm. Subsequently, the transfer AGV switches to the lateral motion mode, moving to the right 3.7 cm. After the movement, the absolute value of the target vehicle's offset relative to the transfer AGV in the longitudinal and lateral directions is less than 1 cm, and the absolute value of the orientation angle offset is less than 0.3°, which meets the transfer AGV's operational error requirements. It is considered that the transfer AGV and the target vehicle have the same orientation angle and coincident geometric center, thus completing the correction target.

[0060] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A commodity vehicle docking attitude correction method based on tire detection, characterized in that, The method comprises the following steps: Step one, when the transfer AGV positions the target commodity vehicle, obtain the original scanning data of the four single-line laser radars installed in the vehicle, and perform laser point cloud data preprocessing; Step two, according to the preprocessed laser point cloud data obtained in step one, obtain the point cloud sets of the left front, left rear, right front and right rear tires of the target commodity vehicle, and further extract the geometric center point coordinate values of the four tires; Step three, according to the geometric center point coordinate values of the four tires obtained in step two, obtain the coordinate values of the vehicle geometric center point; Step four, according to the geometric center points of the left front and right front tires obtained in step two, determine the coordinate values of the vehicle front end center point; Step five, according to the vehicle geometric center point coordinate in step three and the vehicle front end center point coordinate in step four, obtain the horizontal direction offset angle of the target commodity vehicle relative to the transfer AGV; Step six, process the horizontal direction offset angle obtained in step five to obtain the self-rotation direction and self-rotation angle of the transfer AGV; Step seven, process the coordinate of the vehicle geometric center point obtained in step three and the horizontal direction offset angle of the target commodity vehicle relative to the transfer AGV obtained in step five to obtain the displacement correction amount of the longitudinal and lateral movement of the transfer AGV.

2. The method for correcting the docking attitude of the commercial vehicle based on the tire detection according to claim 1, characterized in that: The specific implementation method of step one is that, when the transfer AGV positions the target commodity vehicle, the original scanning data of the left front, right front, left rear and right rear single-line laser radars installed in the vehicle are obtained, and the original scanning data of the single-line laser radars are preprocessed to obtain the point cloud information of the left front, right front, left rear and right rear tires of the target commodity vehicle scanned by the single-line laser radars. The point cloud set of the left front tire is recorded as L1, the point cloud set of the right front tire is recorded as L2, the point cloud set of the left rear tire is recorded as L3, and the point cloud set of the right rear tire is recorded as L4. The data preprocessing includes point cloud coordinate transformation and point cloud threshold filtering.

3. The method of claim 1, wherein: The specific implementation method of step two is that the point cloud sets of the left front, right front, left rear and right rear tires of the commodity vehicle obtained in step one are processed to obtain the center point coordinate values of the four tires of the commodity vehicle, and the center point coordinate values of the left front tire, right front tire, left rear tire and right rear tire are respectively denoted as P1, P2, P3 and P4; and the tire point cloud set L i , the center point coordinate values (P ix , P iy ) of which are calculated by the following formula: where n is the number of laser points in the point cloud set L i where n is the number of laser points in the point cloud set L i for any point P j whose horizontal coordinate is whose vertical coordinate is 4. The method of claim 1, wherein: The specific implementation method of step three is to calculate the target vehicle center point P 中心 (P Δx , P Δy ) according to the left front, right front, left rear and right rear tire center point coordinate values (P ix , P iy ) obtained in step two. ix , iy , 中心 , Δx , Δy 5. The method for correcting the docking attitude of a commercial vehicle based on tire detection according to claim 1, characterized in that: The specific implementation method of step four is to calculate the target car front end center point P according to the left front and right front tire center point coordinate values obtained in step two 前中 :

6. The method of correcting the docking pose of a commercial vehicle based on tire detection of claim 1, wherein: The specific implementation method of step five is to obtain the target commodity vehicle center point P 中心 and the target commodity vehicle front end center point P 前中 obtained in step four Δ to obtain the horizontal direction offset angle θ of the target commodity vehicle relative to the transfer AGV 7. The method of claim 1, wherein: The specific implementation method of step six is that according to θ Δ obtained in step five, the rotation direction and rotation angle θ of the transfer AGV are obtained Δ . If θ Δ is a negative angle, the rotation direction is counterclockwise, and the rotation angle is equal to -θ Δ . If θ Δ is a positive angle, the rotation direction is clockwise, and the rotation angle is equal to θ Δ . The transfer AGV rotates so that the transfer AGV and the target commodity vehicle have the same orientation angle, and the angle correction of the transfer AGV is completed.

8. The method of correcting the docking pose of a commercial vehicle based on tire detection of claim 1, wherein: The specific implementation method of step seven is to obtain the horizontal direction offset angle θ of the target commodity vehicle relative to the transfer AGV according to the target commodity vehicle obtained in step five Δ and the center point P of the target commodity vehicle obtained in step three 中心 (P Δx , P Δy ) to obtain the longitudinal displacement correction amount L of the transfer AGV Δ1 and the lateral displacement correction amount L Δ2 : L Δ1 = P Δx sin θ Δ + P Δy cos θ Δ , L Δ2 = P Δx cos θ Δ - P Δy sin θ Δ Taking the forward direction of the transfer AGV as the longitudinal displacement positive direction, taking the right side of the transfer AGV as the transverse displacement positive direction, longitudinally displacing the transfer AGV L Δ1 , transversely displacing the transfer AGV L Δ2 , so that the transfer AGV is consistent with the target commodity vehicle in the orientation angle and the geometric centers coincide, and the correction target is completed.

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