Method for changing the position of a load on a load-receiving portion of an unmanned transport vehicle

Abstract

The invention relates to a method for changing the position of a load on a load-receiving area of an unmanned transport vehicle, the travel drive of the transport vehicle being controlled by a vehicle controller. Here, the actual position of the load is detected by a detection device connected to the controller, and a load position correction vector is determined by the vehicle controller from the actual position of the load to the desired position of the load on the load-receiving area, and the vehicle controller controls the travel drive such that the transport vehicle accelerates substantially in the opposite direction to the load position correction vector, thereby bringing the load to the desired position of the load on the load-receiving area.

Description

Technical Field

[0001] The present invention relates to a method for changing the position of a load located on a load receiving section of an unmanned transport vehicle, wherein the vehicle's driving drive is controlled by a vehicle controller. Background Technology

[0002] Driverless transport vehicles used for transporting loads are widely used in the logistics sector. Here, automated driverless transport vehicles controlled by a vehicle controller are preferred. For specific functions, such as load delivery, preventing loads from falling off during braking, acceleration, turning, and interaction with other machines, it is crucial to accurately position the load at the pre-set desired location in the load receiving section.

[0003] The positioning of the load on the loading receiving section of a transport vehicle can be implemented in various ways. Thus, the load can be positioned specifically using tools or robots. The load can also be secured to the loading receiving section using form-locking and / or force-locking elements. Elements that actively (e.g., pushers) or passively (e.g., top feeders) can also be used to change the position of the load. Furthermore, the load can be output very precisely from a continuous conveyor to elements that rotate at a coordinated speed (e.g., for outputting to pallets from an automated parcel sorting machine).

[0004] If the accurate positioning of the load on the load receiving section of the transport vehicle cannot be established, this inaccuracy must be taken into account in other operations (e.g., identifying the load position before the load is output), which is correspondingly complicated.

[0005] Methods for changing the position of a load located on a load receiving section of an unmanned transport vehicle are known from DE 20 2020 000 762 U1 and EP 3 699 066 A1. Summary of the Invention

[0006] The purpose of this invention is to provide a solution for unmanned transport vehicles in which the positioning of the load on the transport vehicle is achieved by the transport vehicle itself, without the need for additional positioning elements on the transport vehicle or at the load receiving station.

[0007] According to the present invention, the objective is achieved in a method of the type described above in such a way that the actual position of the load is detected by a detection device connected to a controller, and the vehicle controller determines a load position correction vector from the actual position of the load to the desired position of the load on the load receiving section, and the vehicle controller controls the driving drive such that the transport vehicle accelerates substantially in the direction opposite to the load position correction vector, thereby causing the load to reach the desired position of the load on the load receiving section.

[0008] Using this method, a load on the loading receiver of an unmanned transport vehicle can be positioned at a desired location without additional positioning elements. This is achieved by selectively accelerating the vehicle once or multiple times in the opposite direction of displacement from the actual position to the desired position. After overcoming friction, the load slides to the desired position due to the inertial force acting on the loading receiver. Depending on the specific circumstances (e.g., necessary movement path, friction), a short acceleration may be sufficient. In many applications, precise positioning of the load is not required; it is sufficient to ensure that the load is not located at the edge of the loading receiver and thus within the desired loading area, or that it does not partially protrude outward from the loading receiver. In these cases, the measurement accuracy of the detection device is not critical, and it is not necessary to precisely detect the actual position of the load. The transport vehicle preferably has an omnidirectional drive, which allows for short accelerations in all directions, independent of the current trajectory and thus also in the opposite direction to all necessary load position correction vectors.

[0009] Here, the detection device can be configured to continuously detect the actual position of the load, and the vehicle control device can take the actual position of the load into account. This design is particularly useful when multiple vehicle accelerations are required to move the load.

[0010] Advantageously, the coefficient of friction of the cargo receiving surface is altered before the transport vehicle accelerates in a direction substantially opposite to the cargo position correction vector. This adjusts the contact surface between the cargo receiving section and the cargo during normal vehicle operation, ensuring the cargo remains reliably on the cargo receiving section. Reducing the coefficient of friction before vehicle acceleration for cargo repositioning allows the cargo to slide more easily to the desired position. The vehicle acceleration can be correspondingly smaller, resulting in less deviation of the transport vehicle from its actual travel path.

[0011] According to the first design scheme, the detection device is fixedly and spatially separated from the transport vehicle. In this case, the detection device is naturally positioned in the transport vehicle's travel path so that it can detect the cargo.

[0012] According to the second design scheme, the detection device is connected to the transport vehicle.

[0013] Driverless transport vehicles can move along a pre-defined trajectory. Two variations of this approach can be employed.

[0014] According to the first variant, the vehicle controller controls the driving drive to make the transport vehicle move from the starting point to the ending point of the trajectory on a trajectory with a predetermined desired position. During the movement of the vehicle on the trajectory, the transport vehicle is accelerated to change the position of the load, thereby causing the actual position of the vehicle to deviate from the desired position of the trajectory. After the acceleration of the transport vehicle ends, the vehicle controller re-determines the remaining trajectory to the ending point of the trajectory and controls the driving drive to make the transport vehicle move on the newly determined trajectory.

[0015] Alternatively, according to the second variant, the vehicle controller controls the drive in such a way that the transport vehicle moves from the start point to the end point of the trajectory on a trajectory with a predetermined desired position. During the movement of the vehicle on the trajectory, the transport vehicle is accelerated to change the position of the load, thereby causing the actual position of the vehicle to deviate from the desired position. After the acceleration of the transport vehicle ends, the vehicle controller re-determines a relative vehicle position correction vector that reduces the difference between the current actual position of the vehicle and the current desired position without causing a change in the position of the load. The vehicle controller then controls the drive so that the transport vehicle approaches the desired position using the determined relative vehicle position correction vector and continues to move on the trajectory after reducing the difference between the actual position of the vehicle and the desired position.

[0016] The present invention also relates to an unmanned transport vehicle for implementing the method, the transport vehicle having a detection device connected to the transport vehicle, the transport vehicle having a cargo receiving section and a vehicle controller, the cargo receiving section being disposed on a driving mechanism having a driving drive.

[0017] Especially when it is necessary to accurately detect the actual position of the load, it is preferable that the detection device be a camera.

[0018] At this point, the camera is advantageously positioned below the transparent bottom area of ​​the loading receiving section. Additionally, in addition to the loading's position information, the camera can also detect the loading's optical identification features, such as barcodes or QR codes.

[0019] Alternatively, the detection device can be configured to have a light sensor that monitors the edge of the desired loading area on the loading receiving section. This solution is particularly suitable when precise position determination is not required. Thus, an area can exist on the loading receiving section within which the loading is permitted to be located. If the loading is within this area, no correction is needed. If the loading is at least partially outside the area, correction is required. This is confirmed by monitoring the outer edge of the area from below through a small aperture using light sensors at defined intervals. If at least one light sensor detects the loading, correction is required. In this case, the loading position correction vector is related to the number of sensors currently detecting the loading and the positions of those sensors.

[0020] As a variation, the transport vehicle can also have multiple light sensors arranged in a defined pattern, such as a simple grid, through holes in the cargo receiving section below. The grid should reasonably have a density such that at least one sensor can always detect the cargo. Depending on the sensor density (similar to camera resolution), the actual position of the cargo can be determined at any time with varying degrees of accuracy. Furthermore, with a larger number of sensors, the approximate size of the cargo can also be determined.

[0021] The detection device may not be optically configured, but rather used, for example, to monitor the center of gravity of the load by using appropriate sensors to detect different spring displacements in the wheel spring suspension of the transport vehicle. The detection device may also have ultrasonic sensors or inductive sensors (for identifying metallic loads).

[0022] Furthermore, the present invention also relates to an unmanned transportation system having at least one unmanned transport vehicle, the transport vehicle having a cargo receiving section and a vehicle controller, the cargo receiving section being disposed in a driving mechanism having a driving drive, and the transport vehicle having at least one detection device connected to the controller, the detection device being fixedly and spatially separated from the at least one transport vehicle. In this case, the at least one detection device is preferably a camera. Attached Figure Description

[0023] The present invention will now be described in detail by way of example with reference to the accompanying drawings.

[0024] in:

[0025] Figure 1 A schematic perspective view of an unmanned transport vehicle suitable for implementing the method according to a first design is shown.

[0026] Figure 2 Showing according to Figure 1A side view of the transport vehicle.

[0027] Figure 3 Showing according to Figure 1 A top view of a transport vehicle with a load, the load being in an actual position offset from its intended location.

[0028] Figure 4 Showing with Figure 3 A similar view, showing the load position correction vector,

[0029] Figure 5 Showing according to Figure 1 A perspective view of a transport vehicle showing the actual location of the load.

[0030] Figure 6 The diagram shows a perspective view of a transport vehicle according to a second design, the vehicle carrying a load in an actual position that is offset from the desired position of the load.

[0031] Figure 7 Showing according to Figure 6 A transport vehicle carrying cargo in the desired location.

[0032] Figure 8 Showing the use of according to Figure 1 The illustrative method and process for transport vehicles,

[0033] Figure 9 The diagram shows a perspective view of a transport vehicle according to a third design, the vehicle carrying a load in an actual position that is offset from the desired position of the load.

[0034] Figure 10 Show Figure 9 Side view,

[0035] Figure 11 Showing according to Figure 9 A transport vehicle carrying cargo that is actually in the loading position.

[0036] Figure 12 The field of view of the external camera, which serves as the detection device, is shown according to... Figure 6 A schematic perspective view of the transport vehicle.

[0037] Figure 13 Shown in the field of view of the external camera according to Figure 7 transport vehicles,

[0038] Figure 14 A schematic perspective view of a transport vehicle according to a fourth design is shown, the transport vehicle carrying a load in an actual position that is offset from the desired position of the load.

[0039] Figure 15 Showing according to Figure 14 A transport vehicle carrying cargo in the desired location.

[0040] Figure 16 A schematic perspective view of the transport vehicle according to the fifth design scheme is shown.

[0041] Figure 17 Show Figure 16 Side view,

[0042] Figures 18 to 20 This illustrates the movement of a transport vehicle along a pre-defined trajectory, up to its acceleration.

[0043] Figures 21 to 22 The diagram illustrates the motion of the transport vehicle after acceleration in the first method design scheme, and...

[0044] Figures 23 to 24 The diagram illustrates the motion of the transport vehicle after acceleration in the second method design scheme. Detailed Implementation

[0045] An unmanned transport vehicle for implementing the method according to the invention is generally indicated by 1 in the figure. The transport vehicle 1 is used to transport a load, generally indicated by 2, and has a surface-type load receiving section 3 on which the load 2 is located. The load receiving section 3 is made of, for example, metal or plastic, and in these embodiments, the contact surface between the load receiving section and the load 2 is flat. Furthermore, the transport vehicle 1 has a running gear, generally indicated by 4, with casters or wheels 5 provided on the underside of the running gear.

[0046] In the illustrated embodiment, the load receiving part 3 is not directly mounted on the traveling mechanism 4, but rather an intermediate body is provided between the upper side of the traveling mechanism 4 and the lower side of the load receiving part 3. To secure the load 2 to the load receiving part 3 during transport, according to... Figures 1 to 5 The transport vehicle is provided with an edge limiting structure 6, which extends, for example, only in a portion of the periphery of the cargo receiving section 3.

[0047] The transport vehicle 1 has a drive unit (not shown) that is connected to wheels or casters 5 in a drive linkage, and the drive unit can be controlled by a controller (not shown). Figures 1 to 3 In the illustration, the load 2 is in its actual position, which is located in a corner area of ​​the load receiving section 3. This actual position of the load does not match the desired position of the load; this position of the load 2 is... Figure 5 As shown in the image.

[0048] Therefore, using the method according to the invention, the position of the load 2 should be changed from according to Figures 1 to 3 The actual position of the load was changed according to Figure 5 The desired position of the load is determined. To this end, a detection device, detailed below, is installed, which is connected to the controller of the unmanned transport vehicle and detects the actual position of the load 2. After detecting the actual position of the load, the vehicle controller determines a load position correction vector based on the actual position and the pre-defined desired position of the load. This load position correction vector is in Figure 4 As shown in the figure, the load position correction vector extends from the center of gravity of the load 2 in its actual position to the center of gravity of the load 2 in its desired position, indicated by a dashed line.

[0049] Correction vector for determining the load position Subsequently, the vehicle controller controls the drive mechanism of the transport vehicle, causing the transport vehicle 1 to travel substantially along the same path as the load position correction vector. Accelerating in the opposite direction means that... Figure 4 In other words, it accelerates by tilting to the lower left.

[0050] exist Figure 8 The diagram illustrates the movement of transport vehicle 1. Transport vehicle 1 first moves in region A, for example, in a straight line, and then moves along a correction vector opposite to the position of the load. The vehicle accelerates in the direction of the load into area B. Afterward, the load 2 on the load receiving unit 3 slides to the desired position due to inertia after overcoming friction. Next, the transport vehicle 2 moves in area C in the direction of the original transport path so as to reach the same transport path again in area D.

[0051] Figure 6 The image shows transport vehicle 1, which is in accordance with... Figures 1 to 5 The difference between the transport vehicles is that the loading receiving section 3 does not have an edge restraint structure. The loading 2 is also in its actual position, deviating from the desired loading position, and moves to the desired position through one or more accelerations as described above. Figure 7 The desired location of the load.

[0052] exist Figures 9 to 11 The diagram shows a transport vehicle 1 without edge-limiting structures. The transport vehicle 1 is equipped with a detection device connected to a vehicle controller, which includes, for example, multiple light sensors 7. The light sensors 7 are positioned below a load receiving section 3 and emit a beam 8 vertically upward through an opening in the load receiving section 3. The light sensors 7 are configured to monitor the edges of desired loading areas on the load receiving section 3. Figure 9In this process, the load 2 is positioned such that the light beam from the front light sensor 7 hits the load 2, thereby the light sensor recognizes that the load 2 is not in the desired load area and accordingly the load must be moved on the load receiving part 3. Figure 11 The image shows the load 2 in the desired loading position, where all the optical sensors 7 can emit light beams 8 without being obstructed by the load 2, thus determining that the load 2 is in the desired loading position.

[0053] exist Figure 12 and 13 The diagram illustrates an unmanned transport system for implementing the method using an unmanned transport vehicle 1 and a detection device configured as a camera 9 connected to a controller. The detection device is fixedly and spatially separated from the transport vehicle 1, for example, positioned above the travel path of the transport vehicle 1. The detection area of ​​the camera 9 is shown schematically by a cone 10.

[0054] exist Figure 14 and 15 The image shows a transport vehicle 1, in which a camera (not shown) is integrated as a detection device in the cargo receiving section 3. The camera is positioned below at least a partially transparent bottom region 3a of the cargo receiving section.

[0055] exist Figure 16 and 17 The image shows a transport vehicle 1 with a load 2 in an actual position that is offset from the desired position of the load. In this transport vehicle 1, the wheels 5 are equipped with spring suspension 11, here referring to... Figure 17 Since the load 2 (center of gravity) is positioned outside the desired load location, the spring travel of the two spring suspensions 11 is different. In this case, the detection device has a spring travel sensor (not shown) connected to the controller. If the controller detects that the spring travel of each spring suspension 11 is different, the controller can determine the center of gravity position of the load 2 from the spring travel and thus determine the actual position of the load, and initiate a position change.

[0056] exist Figures 18 to 24 The diagram illustrates two method flows, in which the vehicle controller controls the drive of the transport vehicle 1, causing the transport vehicle 1 to move from the starting point 12 to the ending point 13 along a trajectory with a predetermined desired position. Figure 18 ).

[0057] exist Figures 18 to 20 The diagram shows the starting positions of two process flows. Transport vehicle 1 follows the trajectory T shown by the dashed line and is at the desired position on the trajectory. In contrast, the load 2 is not at the desired position on the load.

[0058] Therefore, according to Figure 19 It must be done in accordance with Figure 19 Load position correction vector The position of load 2 is corrected.

[0059] To correct the load position to its actual position, now, while transport vehicle 1 is moving along trajectory T, transport vehicle 1 is reversed relative to the load position correction vector. Accelerate. Next, the vehicle's actual position deviates from the expected trajectory position. Figure 20 This situation is illustrated in the diagram. To enable transport vehicle 1 to reach the target point, i.e., the trajectory endpoint 13, two different method flows are proposed. Here, in... Figure 20 and 21 The first method flow is shown below:

[0060] After the acceleration of transport vehicle 1 (travel path F) ends, the vehicle controller re-determines the remaining trajectory to the trajectory endpoint 13 and controls the driving drive to make transport vehicle 1 move on the newly determined trajectory T1. The old trajectory is deactivated.

[0061] Alternative sites, based on Figure 23 and 24 The configuration is as follows: after the acceleration of transport vehicle 1 ends, the vehicle controller determines a relative vehicle position correction vector. This vector reduces the difference between the current actual vehicle position and the desired trajectory position without simultaneously causing a change in the position of the load. The controller then controls the drive mechanism so that the transport vehicle uses the determined relative vehicle position correction vector to approach the desired trajectory position and continues moving on the (original) trajectory T after reducing the difference between the actual vehicle position and the desired trajectory position. Thus, in this case, no new trajectory is determined, and the vehicle continues moving on the original trajectory T until the trajectory endpoint 13.

[0062] List of reference numerals

[0063] 1. Transport vehicles

[0064] 2. Loading

[0065] 3. Loading receiving section

[0066] 3a Transparent bottom area

[0067] 4. Driving mechanism

[0068] 5 wheels

[0069] 6. Edge-constrained structure

[0070] 7. Optical Sensor

[0071] 8 beams

[0072] 9 cameras

[0073] 10 Conical

[0074] 11. Spring suspension

[0075] 12. Trajectory Starting Point

[0076] 13. End of the trajectory

[0077] T and T1 trajectories

[0078] Load position correction vector A region

[0079] Area B

[0080] Area C

[0081] Area D

[0082] F. Driving route.

Claims

1. A method for changing the position of a load located on a load receiving section of an unmanned transport vehicle, wherein a vehicle controller controls the drive mechanism of the transport vehicle, the method comprising: The actual position of the load is detected by a detection device connected to the controller, and the vehicle controller determines a load position correction vector from the actual position of the load to the desired position of the load on the load receiving section. The vehicle controller then controls the driving drive to cause the transport vehicle to accelerate in the opposite direction to the load position correction vector, thereby causing the load to reach the desired position on the load receiving section. The load then slides on the load receiving section into the desired loading position by means of inertial force.

2. The method according to claim 1, characterized in that, The detection device continuously detects the actual position of the load, and the vehicle controller takes the actual position of the load into account.

3. The method according to claim 1 or 2, characterized in that, Before the transport vehicle accelerates in the direction opposite to the load position correction vector, the coefficient of friction of the surface of the load receiving part is changed.

4. The method according to claim 1 or 2, characterized in that, The detection device is fixed and spatially separated from the transport vehicle.

5. The method according to claim 1 or 2, characterized in that, The detection device is connected to the transport vehicle.

6. The method according to claim 1 or 2, characterized in that, The vehicle controller controls the driving drive to make the transport vehicle move from the starting point to the ending point of the trajectory on a trajectory with a predetermined desired position. During the movement of the transport vehicle on the trajectory, the vehicle is accelerated to change the position of the load, thereby causing the actual position of the vehicle to deviate from the desired position of the trajectory. After the acceleration of the transport vehicle ends, the vehicle controller re-determines the remaining trajectory to the ending point of the trajectory and controls the driving drive to make the transport vehicle move on the newly determined trajectory.

7. The method according to claim 1 or 2, characterized in that, The vehicle controller controls the driving drive to move the transport vehicle from the starting point to the ending point of the trajectory along a trajectory with a pre-set desired position. During the movement of the transport vehicle along the trajectory, acceleration is applied to change the position of the load, thereby causing the actual position of the vehicle to deviate from the desired position. After the acceleration of the transport vehicle ends, the vehicle controller determines a relative vehicle position correction vector that reduces the difference between the current actual vehicle position and the current desired position without causing a change in the position of the load. The vehicle controller then controls the driving drive to move the transport vehicle closer to the desired position using the determined relative vehicle position correction vector, and the transport vehicle continues to move along the trajectory after reducing the difference between the actual vehicle position and the desired position.

8. An unmanned transport vehicle for implementing the method according to claim 5, 6 or 7, the transport vehicle having a cargo receiving section (3) and a vehicle controller, the cargo receiving section being disposed on a driving mechanism (4) having a driving drive, characterized in that, The transport vehicle (1) is equipped with a detection device (7, 9) connected to the vehicle controller.

9. The transport vehicle according to claim 8, characterized in that, The detection device is a camera (9).

10. The transport vehicle according to claim 9, characterized in that, The camera (9) is located below the transparent bottom area (3a) of the loading receiving part (3).

11. The transport vehicle according to claim 8, characterized in that, The detection device has a light sensor (7) that monitors the edge of the desired loading area on the loading receiving section (3).

12. An unmanned transport system for implementing the method according to claim 4, 6 or 7, the transport system having at least one unmanned transport vehicle (1), the transport vehicle having a cargo receiving unit (3) and a vehicle controller, the cargo receiving unit being disposed on a driving mechanism (4) having a driving drive, and the transport vehicle having at least one detection device (7, 9) connected to the controller, the detection device being fixedly and spatially separated from the at least one transport vehicle (1).

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