An automatic container placing method for external container trucks based on area array laser scanning

Abstract

The application provides an automatic container placing method of external container truck based on surface array laser scanning, relates to the field of port automation technology, and comprises the following steps: receiving a PLC collection signal, and starting collection of point cloud information of the external container truck plate by a 3D surface array laser scanner; extracting a lock head feature through the point cloud information of the external container truck plate, solving the coordinates of four lock tip points on the external container truck plate in an XOY plane, and reporting a corresponding error code to the PLC if the lock head feature is not successfully extracted; solving the coordinates of the centers of four lock holes of a container bottom carried by a spreader in the XOY plane through a spreader posture; solving a rotation angle and a size vehicle direction translation amount of the spreader to the external container truck plate adjustment alignment through affine transformation; and sending the calculation results to the PLC, performing offset adjustment of the spreader angle and the size vehicle direction after the PLC receives the adjustment amount, and automatically placing the container after the adjustment is completed. The automatic operation function in the container placing process of the external container truck is realized, and the automation degree of the gantry crane and the efficiency of the full-automatic operation are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of port automation, and particularly relates to an automatic container placing method for external container trucks based on planar array laser scanning. BACKGROUND

[0002] With the acceleration of economic globalization, more and more production and operation activities and resource allocation processes gradually expand to every corner of the world. The role and position of modern ports in social and economic development have thus undergone profound changes, and various schemes for improving operational efficiency have been continuously proposed and applied, and port operation automation has gradually become a trend. Container transportation is an important development trend of global transportation industry. To meet the requirements of automatic container loading and unloading at the wharf, how to automatically place containers by external container trucks is one of the problems that need to be solved in the current automated process. At present, there are few examples of fully automatic operation of external container trucks at container terminals, and most of them only solve the deviation in the two-dimensional direction of the container truck / car / dolly by guiding the container truck, and the positioning accuracy is low, and the deviation in the angle direction has not been properly solved, so the manual intervention rate is high and the adjustment failure rate is high in actual application.

[0003] Chinese Patent CN110619645A "Automatic identification and positioning device and method of container trailer under bridge crane" discloses an automatic identification and positioning device and method of container trailer under bridge crane, which identifies and positions the vehicle and container through a camera to realize automatic loading and unloading of containers at the wharf. However, the above method is more inclined to identify the vehicle, and the container identification is incidental, and the accuracy of camera image recognition is low, so there may be deviation when placing the container, which poses a safety hazard. SUMMARY

[0004] Therefore, the present application provides an automatic container placing method for external container trucks based on planar array laser scanning, which solves the problem of low accuracy of current container recognition methods using cameras, deviation when placing containers, and safety hazards.

[0005] The technical scheme of the present application is as follows: The present application provides an automatic container placing method for external container trucks based on planar array laser scanning, which includes the following steps:

[0006] S1, receiving a PLC acquisition signal, and starting to collect point cloud information of the external container truck plate by a 3D planar array laser scanner;

[0007] S2, extracting the lock head feature from the external container truck plate point cloud information, solving the coordinates of the four lock tip points on the external container truck plate in the XOY plane, and reporting the corresponding error code to the PLC if the lock head feature is not successfully extracted;

[0008] S3, solving the coordinates of the four lock hole centers of the container bottom carried by the spreader in the XOY plane by the spreader attitude.

[0009] S4, solving the rotation angle and the size of the truck direction translation of the spreader to the external truck plate adjustment by affine transformation;

[0010] S5, sending the calculation result to the PLC, the PLC receiving the adjustment amount and adjusting the spreader angle and the size of the truck direction offset, and automatically lowering the container after the adjustment is completed.

[0011] Preferably, step S1 specifically comprises:

[0012] A world coordinate system is established, the point cloud coordinate system is rotated to coincide with the world coordinate system by rotating calibration of the 3D area array laser scanner, and then translation calibration is performed to make the position relationship of each point of the point cloud coincide with the world coordinate system.

[0013] Further preferably, step S1 further comprises:

[0014] The point cloud information collected by the 3D area array laser scanner is converted into the world coordinate system through matrix rotation transformation R and translation transformation T, and the conversion relationship is:

[0015]

[0016] Wherein, x w , y w , z w are the world coordinate system coordinates, x lidar-i , y lidar-i , z lidar-i are the corresponding point cloud coordinate system coordinates, R i is the rotation transformation, and T i is the translation transformation.

[0017] Preferably, step S2 specifically comprises:

[0018] According to the difference between the truck plate point cloud and the lock head point cloud on the truck plate in the outline distribution, the point cloud features of the two lock heads near the radar side on the truck plate are extracted, the position information of the lock tip points is obtained from the highest points of the lock head point cloud, and according to the three-dimensional position information of the two lock tip points near the radar side, the two lock tip points on the far radar side are projected onto the XOY plane to obtain the position information of the two lock tip points in the XOY plane.

[0019] Further preferably, step S2 further comprises:

[0020] The coordinates of the two lock tip points near the radar side are (x1, y1) and (x2, y2), the distance of the truck plate in the width direction is W, the distance of the truck plate in the length direction is L, and the deflection angle is Then the position relationship of the two lock tip points on the far radar side in the XOY plane is:

[0021]

[0022]

[0023]

[0024]

[0025] wherein (x3, y3) and (x4, y4) are the XOY plane coordinates of the two far radar side lock points in the world coordinate system.

[0026] Further preferably, the step S2 further comprises:

[0027] The XOY plane coordinates of the four lock points in the world coordinate system are transferred to the XOY plane coordinates of the four lock points in the hoist coordinate system by the position of the trolley in the world coordinate system and the hoist attitude:

[0028] x si = x i - Δx t - Δx s

[0029] y si = y i - Δy t - Δy s

[0030] wherein x i , y i are the XOY plane coordinates of the four lock points in the world coordinate system, Δx t , Δy t are the position of the trolley in the world coordinate system, Δx s , Δy s are the offset of the hoist coordinate system relative to the trolley coordinate system, x si , y si are the XOY plane coordinates of the four lock points in the hoist coordinate system.

[0031] Preferably, the step S3 specifically comprises:

[0032] Let the offset angle B be the distance from the box center to the lock hole center, and A be the distance of the lock hole center in the width direction of the trolley, according to the hoist attitude information (x s , y s , Δθ), the XOY plane coordinates of the four lock hole centers of the box carried by the hoist in the hoist coordinate system are calculated, x s , y s are both 0, Δθ is the value of the angle between the line connecting the box center and the lock hole center and the y axis of the hoist coordinate system minus θ, and the four lock hole center coordinates are:

[0033] x's1 = -B*sin(θ + Δθ)

[0034] y' s1 = B*cos(θ - Δθ)

[0035] x' s2 = -B*sin(θ + Δθ)

[0036] y' s2 = -B*cos(θ - Δθ)

[0037] x' s3 = B*sin(θ + Δθ)

[0038] y' s3 = B*cos(θ + Δθ)

[0039] x' s4 = -B*sin(θ - Δθ)

[0040] y' s4 = -B*cos(θ + Δθ)

[0041] wherein (x' si , y' si )(i = 1, 2, 3, 4) are the XOY plane coordinates of the corresponding lock hole center in the sling coordinate system.

[0042] Preferably, the step S4 specifically comprises:

[0043] According to the coordinates (x si , y si ) of the four lock tips in the sling coordinate system and the coordinates (x' si , y' si ) of the four lock hole centers of the tank bottom, an affine transformation is used to solve the conversion matrix M of the sling to the external truck plate posture:

[0044]

[0045] wherein, is the angle of rotation required for the adjustment of the sling to the external truck plate, and Δx, Δy are the translation amounts required for the adjustment of the sling to the external truck plate.

[0046] Preferably, the step S5 specifically comprises:

[0047] Real-time communication is established with the PLC through TCP communication, the PLC provides a signal for data acquisition, data is collected through the 3D area array laser scanner after receiving the PLC acquisition signal, and the collected data is processed and output to the PLC end. If a fault occurs in the middle, it is directly reported to the PLC for fault handling.

[0048] The automatic container placing method of external container trucks based on planar array laser scanning has the following beneficial effects relative to the prior art:

[0049] (1) The lock head features on the truck plate are extracted by multiple 3D planar array laser scanners respectively, the truck plate posture of the external container truck is calculated based on the lock head features, and the real-time posture of the spreader, i.e. the movement offset of the spreader relative to the truck plate of the external container truck, is combined to realize the function of automatic adjustment and alignment of the spreader to the truck plate of the external container truck, thereby completing the automatic container placing process of the external container truck;

[0050] (2) The point cloud information of the truck plate of the external container truck is converted to the same coordinate as the spreader by converting between the world coordinate system and the spreader coordinate system, thereby solving the deviation caused by different reference systems;

[0051] (3) The conversion matrix is solved by affine transformation, i.e. the angle of rotation and the amount of translation required for the adjustment and alignment of the spreader to the truck plate of the external container truck, to accurately control the container placing process and improve the success rate of container placing. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0053] Figure 1 A flow chart of the automatic container placing method of external container trucks based on planar array laser scanning of the present application;

[0054] Figure 2 A world coordinate system diagram of the automatic container placing method of external container trucks based on planar array laser scanning of the present application;

[0055] Figure 3 A rotation change R solving diagram of the automatic container placing method of external container trucks based on planar array laser scanning of the present application;

[0056] Figure 4 A 3D planar array laser scanner calling strategy diagram of the automatic container placing method of external container trucks based on planar array laser scanning of the present application;

[0057] Figure 5 A lock head point cloud feature extraction diagram of the automatic container placing method of external container trucks based on planar array laser scanning of the present application;

[0058] Figure 6 A far radar side lock tip coordinate solving diagram of the automatic container placing method of external container trucks based on planar array laser scanning of the present application

[0059] Figure 7 It is a world coordinate system, trolley coordinate system and lifting appliance coordinate system conversion schematic diagram of an automatic container placing method of external container truck based on planar array laser scanning of the application;

[0060] Figure 8 It is a lifting appliance posture solving four lower hole coordinates of the box carried by the lifting appliance schematic diagram of the automatic container placing method of external container truck based on planar array laser scanning of the application;

[0061] Figure 9 It is a technical roadmap of the automatic container placing method of external container truck based on planar array laser scanning of the application. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the application will be clearly and completely described in combination with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0063] EMBODIMENT

[0064] An automatic container placing method of external container truck based on planar array laser scanning is provided, as shown in the figure, comprising the following steps: Figure 1

[0065] S1, receiving PLC collection signals, starting to collect point cloud information of the external container truck plate by the 3D planar array laser scanner;

[0066] S2, extracting the lock head features through the external container truck plate point cloud information, solving the coordinates of the four lock tip points on the external container truck plate in the XOY plane, and reporting the corresponding error code to the PLC if the lock head features are not successfully extracted;

[0067] S3, solving the coordinates of the four lock hole centers of the box bottom carried by the lifting appliance in the XOY plane through the lifting appliance posture;

[0068] S4, solving the rotation angle and the size car direction translation amount of the lifting appliance to the external container truck plate adjustment alignment through affine transformation;

[0069] S5, sending the calculation results to the PLC, and adjusting the lifting appliance angle and the size car direction offset after the PLC receives the adjustment amount, and automatically lowering the container after the adjustment is completed.

[0070] The step S1 specifically comprises:

[0071] A world coordinate system is established, the point cloud coordinate system is rotated to coincide with the world coordinate system through rotation calibration of the 3D planar array laser scanner, and then translation calibration is performed to make the position relationship of each point of the point cloud coincide with the world coordinate system.​

[0072] The default world coordinate system is constructed as follows: the direction of the trolley is the X axis, and the forward direction is the positive direction of the X axis; the direction of the large trolley is the Y axis, and the left direction is positive; the lifting direction is the Z axis, and the upward direction is positive, as shown in Figure 2 .

[0073] Since the posture of the laser scanner cannot be determined during installation, the original data collected by the scanner and the actual world coordinate system have rotation and translation deviations, and all scanner coordinate systems need to be unified to the same world coordinate system through calibration.

[0074] 3D area array laser calibration includes rotation calibration and translation calibration. Rotation calibration refers to the process of rotating the point cloud coordinate system XYZ axis to coincide with the world coordinate system XYZ axis; translation calibration refers to the process of making the position relationship of each point of the point cloud coincide with the position of the corresponding point of the world coordinate system through translation in the XYZ three dimensions after rotation calibration is completed.

[0075] The point cloud information collected by the 3D area array laser scanner is converted into the world coordinate system through matrix rotation transformation R and translation transformation T, and the conversion relationship is:

[0076]

[0077] Wherein, x w , y w , z w are world coordinate system coordinates, x lidar-i , y lidar-i , z lidar-i are corresponding point cloud coordinate system coordinates, R i is a rotation transformation, and T i is a translation transformation.

[0078] Rotation calibration: the device coordinate system of the 3D area array laser scanner needs to be rotated to be flush with the world coordinate system, and the Euler angles of three-dimensional rotation, i.e., the pitch angle, the yaw angle, and the roll angle, need to be solved. The present application takes a container as a calibration target, and point cloud information of the vertical surface of the placed flush container and the ground is collected by 3D area array laser radar scanning, the normal vectors of the two surfaces are calculated by point cloud algorithm, the pitch angle, the yaw angle, and the roll angle are solved through the two sets of normal vectors, and the rotation change R is obtained, as shown in Figure 3 .

[0079] The point cloud of the vertical surface and the horizontal surface of the container is collected by area array laser radar scanning, wherein N x , N z are the normal vectors of the vertical surface and the horizontal surface, respectively, and the Euler angles of rotation around the XYZ axis are denoted as α, β, and γ. The normal vectors N x , N zThe values of the Euler angles alpha, beta and gamma and the corresponding rotation transformation R can be calculated by solving the values of beta and gamma with the sling coordinate system X axis direction vector (1, 0, 0) and solving the values of alpha and beta with the sling coordinate system Z axis direction vector (0, 0, 1).

[0080] Translation calibration: by extracting the coordinates of the box corner points in the point cloud, and performing translation mapping with the coordinates of the box corner points in the world coordinate system, the translation transformation T is obtained.

[0081] The strategy of the 3D area array laser scanner is called.

[0082] The standard containers of the container terminal are mainly 20 feet and 40 feet, when the truck drags the container to the gantry crane runway, the truck will first guide itself to the position near the 20 feet or 40 feet, at this time, the spreader will be automatically adjusted to the length of 20 feet or 40 feet according to the size of the working container, when the spreader is 20 feet long, the 20 feet around area array laser is called for detection, when the spreader is 40 feet long, the 40 feet around area array laser is called for detection, and the detection schematic diagram is as shown in Figure 4 .

[0083] The step S2 specifically comprises:

[0084] According to the difference between the point cloud of the truck plate and the point cloud of the lock head on the truck plate in the contour distribution, the point cloud features of the two lock heads near the radar side on the truck plate are extracted, the position information of the lock tip points is obtained from the highest points of the lock head point cloud, and the position information of the two lock tip points on the far radar side in the XOY plane is solved by projecting the three-dimensional position information of the two lock tip points near the radar side to the XOY plane.

[0085] After the 20 feet around or 40 feet around radar collects complete external truck plate point cloud data, according to the difference between the point cloud of the truck plate and the point cloud of the lock head on the truck plate in the contour distribution, the point cloud features of the two lock heads near the radar side on the truck plate are extracted, as shown in Figure 5 , the left side is the extraction of the 40 feet left lock head, and the right side is the extraction of the 40 feet right lock head.

[0086] After the lock head point cloud features are extracted, the position information of the lock tip points can be obtained from the highest points of the lock head point cloud. In the XOY plane, the distance size relationship between the four lock heads on the external truck plate is unchanged, and the position information of the two lock tip points on the far radar side in the XOY plane can be solved by projecting the three-dimensional position information of the two lock tip points near the radar side to the XOY plane, as shown in Figure 6 .

[0087] The coordinates of the two lock tip points near the radar side are (x1, y1) and (x2, y2), the distance of the external truck lock head in the truck plate width direction is W, and the distance in the truck plate length direction is L, and the deflection angle is The position relationship of the two lock tip points on the far radar side in the XOY plane is:

[0088]

[0089]

[0090]

[0091]

[0092] wherein (x3, y3) and (x4, y4) are the XOY plane coordinates of the two lock tip points on the far radar side in the world coordinate system.

[0093] The XOY plane coordinates of the four lock tip points of the external container truck plate in the world coordinate system have been obtained, and since the rotation of the spreader is performed around the spreader center, it is also necessary to transfer the XOY coordinates of the four lock tips to the spreader center coordinate system through the position of the trolley in the world coordinate system and the spreader attitude, and the conversion relationship is as shown in the following formula (4): Figure 7 w wherein O trolley is the world coordinate system, O spreader is the trolley coordinate system, and O

[0094] The XOY plane coordinates of the four lock tip points in the world coordinate system are transferred to the spreader center coordinate system through the position of the trolley in the world coordinate system and the spreader attitude:

[0095] x si =x i -Δx t -Δx s

[0096] y si =y i -Δy t -Δy s

[0097] wherein x i , y i are the XOY plane coordinates of the four lock tip points in the world coordinate system, Δx t , Δy t are the position of the trolley in the world coordinate system, Δx s , Δy s are the offset of the spreader coordinate system relative to the trolley coordinate system, and x si , y si are the XOY plane coordinates of the four lock tip points in the spreader coordinate system.

[0098] The step S3 specifically comprises:

[0099] Let the offset angle​ B is the distance from the center of the box to the center of the locking hole, A is the distance of the center of the locking hole in the width direction of the truck plate, and the pose information (x s ,y s , Δθ) of the spreader is used to calculate the XOY plane coordinates of the four locking hole centers of the box carried by the spreader in the spreader coordinate system, x s ,y s , Δθ is the value of the angle between the line connecting the center of the box and the center of the locking hole and the y-axis of the spreader coordinate system minus θ, and the solving principle diagram is shown in Figure 8 , and the four locking hole center coordinates are:

[0100] x' s1 = -B * sin (θ-Δθ)

[0101] y' s1 =B*cos(θ-Δθ)

[0102] x' s2 =-B*sin(θ+Δθ)

[0103] y' s2 =-B*cos(θ+Δθ)

[0104] x' s3 =B*sin(θ-Δθ)

[0105] y' s3 =-B*cos(θ-Δθ)

[0106] x' s4 =B*sin(θ+Δθ)

[0107] y' s4 =B*cos(θ+Δθ)

[0108] where (x' si ,y' si )(i = 1, 2, 3, 4) are the XOY plane coordinates of the corresponding locking hole center in the spreader coordinate system.

[0109] Step S4 specifically includes:

[0110] According to the coordinates (x si ,y si ) of the four locking points in the spreader coordinate system and the coordinates (x' si ,y' si ) of the four locking hole centers at the bottom of the box carried by the spreader, an affine transformation is used to solve the conversion matrix M of the pose of the spreader to the truck plate of the external truck:

[0111]

[0112] where, The angle of rotation of the hoist to the external container truck plate is Δx, and the translation amount of the hoist to the external container truck plate is Δy.

[0113] The step S5 specifically comprises:

[0114] Real-time communication is established with the PLC through TCP communication, the PLC provides a signal for data acquisition, data is collected through the 3D area array laser scanner after receiving the PLC acquisition signal, and the collected data is processed and output to the PLC end, and if a fault occurs in the middle, the fault is directly reported to the PLC for fault processing.

[0115] As shown in Figure 9 Fig. 1 is a technical roadmap of an automatic container placing method for external container trucks based on area array laser scanning, and the specific process is as follows:

[0116] 1) The system receives the PLC acquisition signal, and the 3D area array laser starts collecting point cloud information of the external container truck plate;

[0117] 2) The lock head feature is extracted through the point cloud information of the external container truck plate, and the coordinates of the four lock tip points on the external container truck plate in the XOY plane are solved, and if the lock head feature is not extracted successfully, the corresponding error code is reported to the PLC;

[0118] 3) The coordinates of the four lock hole centers of the box bottom carried by the hoist in the XOY plane are solved through the hoist posture;

[0119] 4) The rotation angle and the translation amount in the large and small car direction of the hoist to the external container truck plate adjustment are solved through affine transformation;

[0120] 5) The system calculation result is sent to the PLC, the PLC receives the adjustment amount and adjusts the hoist angle and the offset in the large and small car direction, and after the adjustment is completed, it is automatically lowered, that is, the whole process of the automatic container placing of the external container truck is completed.

[0121] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An automatic container placing method for external container trucks based on area array laser scanning, characterized in that, It comprises the following steps: S1, receiving a PLC collection signal, starting to collect point cloud information of the external container truck plate by a 3D area array laser scanner; The step S1 specifically comprises: Establishing a world coordinate system, rotating the point cloud coordinate system to coincide with the world coordinate system through rotation calibration of the 3D area array laser scanner, and then performing translation calibration to make the position relationship of each point of the point cloud coincide with the world coordinate system; S2, extracting the lock head features from the external container truck plate point cloud information, solving the coordinates of the four lock tip points on the external container truck plate in the XOY plane, and reporting the corresponding error code to the PLC if the lock head features are not successfully extracted; The step S2 specifically comprises: According to the difference between the truck plate point cloud and the lock head point cloud on the truck plate in the contour distribution, the point cloud features of the two lock heads near the radar side truck plate are extracted, the position information of the lock tip points is solved from the highest point of the lock head point cloud, and the three-dimensional position information of the two lock tips near the radar side is projected to the XOY plane, and the position information of the two lock tips far from the radar side in the XOY plane is solved; S3, solving the coordinates of the four lock hole centers of the box bottom carried by the spreader in the XOY plane through the spreader posture; S4, solving the rotation angle and the size of the truck direction translation of the spreader to the external container truck plate adjustment alignment through affine transformation; S5, sending the calculation results to the PLC, and the PLC receives the adjustment amount to adjust the offset of the spreader angle and the size of the truck direction, and automatically releases the container after the adjustment is completed.

2. The automatic container placing method for external container trucks based on area array laser scanning according to claim 1, characterized in that, The step S1 further comprises: The point cloud information collected by the 3D area array laser scanner is converted to the world coordinate system through matrix rotation transformation R and translation transformation T, and the conversion relationship is: where x w , y w , z w are world coordinate system coordinates, x lidar-i , y lidar-i , z lidar-i are corresponding point cloud coordinate system coordinates, R i is a rotation transformation, and T i is a translation transformation.

3. The automatic container placing method for external container trucks based on area array laser scanning according to claim 1, characterized in that, The step S2 further comprises: The coordinates of the two lock tip points near the radar side are (x1, y1) and (x2, y2), the distance of the outer container lock head in the width direction of the truck plate is W, the distance in the length direction of the truck plate is L, and the deflection angle is The position relationship of the two lock tip points far from the radar side in the XOY plane is: Wherein, (x3, y3) and (x4, y4) are the XOY plane coordinates of the two lock tip points far from the radar side in the world coordinate system.

4. The automatic container placing method for external container trucks based on area array laser scanning according to claim 3, characterized in that, The step S2 further comprises: The XOY plane coordinates of the four lock tip points in the world coordinate system are transferred to the spreader center coordinate system through the position of the trolley in the world coordinate system and the spreader posture: x si = x i - Δx t - Δx s y si = y i - Ay t - Ay s wherein x i ,y i are the XOY plane coordinates of the four lock tips in the world coordinate system, Δx t ,Δy t are the position of the trolley in the world coordinate system, Δx s ,Δy s are the offset of the spreader coordinate system relative to the trolley coordinate system, x si ,y si are the XOY plane coordinates of the four lock tips in the spreader coordinate system.

5. The automatic container placing method for external container trucks based on area array laser scanning according to claim 4, characterized in that, The step S3 specifically comprises: Set the offset angle B is the distance from the center of the box to the center of the lock hole, A is the distance of the center of the lock hole in the width direction of the car plate, according to the attitude information (x s ,y s ,Δθ) of the spreader, the plane coordinates of the four lock hole centers of the box carried by the spreader under the spreader coordinate system are calculated, x s ,y s are all 0, and Δθ is the value of the included angle between the line connecting the center of the box and the center of the lock hole and the y-axis of the spreader coordinate system minus θ, and the four lock hole center coordinates are: x' s1 = -B * sin(θ - Δθ) y' s1 = B * cos(θ - Δθ) x' s2 = -B * sin(θ + Δθ) y' s2 = -B*cos(θ+Δθ) x' s3 = B * sin(θ - Δθ) y' s3 = -B*cos(θ-Δθ) x' s4 = B * sin(θ + Δθ) y' s4 = B * cos(θ + Δθ) wherein (x si ,y si )(i = 1, 2, 3, 4) are the XOY plane coordinates of the corresponding lock hole center in the sling coordinate system.

6. The automatic container placing method for external container trucks based on area array laser scanning according to claim 5, characterized in that, The step S4 specifically comprises: According to the coordinates (x si ,y si ) of the four locking points in the sling coordinate system and the coordinates (x' si ,y' si ) of the centers of the four locking holes of the bottom of the box carried by the sling, an affine transformation is used to solve the conversion matrix M of the posture of the sling to the external truck plate: wherein, is the angle of rotation needed for the spreader to align with the external truck bed, and Δx, Δy are the translation needed for the spreader to align with the external truck bed.

7. The automatic container placing method for external container trucks based on area array laser scanning according to claim 1, characterized in that, The step S5 specifically comprises: Through TCP communication, real-time communication with the PLC is established, the PLC provides a data collection signal, and after receiving the PLC collection signal, data is collected by the 3D area array laser scanner, and the collected data is processed and output to the PLC end, and if a fault occurs in the middle, it is directly reported to the PLC for fault handling.

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