Automated guided vehicle, automated guided vehicle control method, and automated guided vehicle control program

Abstract

To provide a technology capable of preventing an event that a shelf collides with a person or an object and falls down and an event that the shelf falls down by detecting an external force or a load collapse.SOLUTION: An automated guided vehicle according to an embodiment includes an interface configured to receive a transport work plan, and a processor configured to control a lift device included in the automated guided vehicle to lift a transport object after the automated guided vehicle is moved to a position where the transport object is disposed according to the transport work plan, measure a position of a center of gravity of the transport object based on a measurement result of a pressure sensing element disposed on an upper surface of the lift device while the automated guided vehicle is moved to a destination based on the transport work plan, and control a tilt of a tilt stage using the tilt stage including a rotation mechanism having a rotation axis at least in a moving direction according to the measured position of the center of gravity.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an automated guided vehicle, an automated guided vehicle control method, and an automated guided vehicle control program. [Background technology]

[0002] In recent years, the volume of various products (hereinafter referred to as "goods") handled at warehouses such as distribution centers for logistics has increased, and automation of goods handling has been promoted to reduce the workload of workers. For example, various automated devices cooperate with each other according to instructions from a higher-level device, and shelves on which goods are stored are transported by automatic guided vehicles or the like.

[0003] An AGV is equipped with an obstacle sensor, and if it collides with a person or an object, the AGV will make an emergency stop in response to the sensor's detection. However, if the AGV collides with an object or other object at a location other than the sensor, the AGV will continue traveling without stopping. For example, if a worker collides with the top of the AGV at a workstation, or if a shelf protruding from the AGV comes into contact with another AGV, the AGV will continue traveling because no sensors are attached to these locations. If the AGV continues traveling despite such a collision, the worker may collide with the shelf and fall, or the worker may be caught in the collapse of the shelf. For example, Patent Document 1 discloses a technology for preventing load collapse. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-135469 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 does not detect external forces acting on the shelves, and therefore has the problem of not being able to detect when an external force is acting on a shelf that is not an automated guided vehicle.

[0006] The present invention provides a technology that can prevent events in which a shelf collides with a person or object and falls over, and events in which the shelf itself falls over, by detecting external force or load collapse. [Means for solving the problem]

[0007] An automated guided vehicle according to an embodiment includes an interface that receives a transport operation plan, and a processor that moves the automated guided vehicle to a position where an object to be transported is placed in accordance with the transport operation plan, and then controls a lifting device provided on the automated guided vehicle to lift the object, and while the automated guided vehicle is moving to a destination based on the transport operation plan, measures the position of the center of gravity of the object to be transported based on the measurement results of a pressure-sensitive element provided on the upper surface of the lifting device, and controls the tilt of the tilting stage using a tilting stage equipped with a rotation mechanism having a rotation axis at least in the direction of movement according to the measured position of the center of gravity. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual diagram illustrating an example of a logistics system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of an automatic guided vehicle according to the embodiment. [Figure 3] FIG. 3 is a diagram showing an example of the appearance and cross section of an automatic guided vehicle. [Figure 4] FIG. 4 is a diagram showing an example of the arrangement of pressure-sensitive elements and an example of the measured intensity sensed by the pressure-sensitive elements when a shelf is placed on a lifting device. [Figure 5] FIG. 5 is a flowchart showing an example of the transport operation of the automatic guided vehicle according to the embodiment. [Figure 6] FIG. 6 is a diagram showing an example of the operation of the tilt stage when the center of gravity of the shelf is shifted. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an automated guided vehicle, an automated guided vehicle control method, and an automated guided vehicle control program will be described in detail with reference to the drawings. In the following embodiments, parts with the same numbers perform the same operations, and redundant description will be omitted. For example, when there are multiple identical or similar elements, a common symbol may be used to describe each element without distinguishing between them, or a sub-number may be used in addition to the common symbol to describe each element with distinction between them.

[0010] In the following description, the term "A" or "B" means at least one of A or B, and the term "A," "B," or "C" means at least one of A, B, or C. Furthermore, the term "A" and "B" also means at least one of A and B, and the term "A," "B," and "C" means at least one of A, B, and C.

[0011] [Embodiment] (composition) FIG. 1 is a conceptual diagram illustrating an example of a logistics system according to an embodiment. As shown in FIG. 1, the warehouse system S includes a warehouse management system (WMS) 1 and a warehouse processing system 2.

[0012] The warehouse processing system 2 is an example of an item processing system, and includes a warehouse execution system (WES) 3, a warehouse control system (WCS) 4, an operator terminal 5, a digital assortment system (DAS) 6, an automated guided vehicle 7, shelves 8, etc.

[0013] The WMS1 and the WES3 may be connected via a network. Here, the network is, for example, a local area network (LAN). The WES3, the WCS4, the worker terminal 5, and the DAS6 may be connected via a network. Furthermore, the WCS4 and the automated guided vehicle 7 may each be connected via a network. Here, the WCS4 and the automated guided vehicle 7 may be connected to the network wirelessly.

[0014] The WMS1 can be configured with one or more computers, i.e., processors, memories, interfaces, etc. The processors can be central processing units (CPUs), micro processing units (MPUs), digital signal processors (DSPs), etc. The WMS1 receives an order list from an upper server and transmits the order list to the WES3. The order list may be received during any of a warehousing operation, a warehousing operation, or an inventory operation.

[0015] The WES3 (server) can be configured with one or more general-purpose computers, i.e., a processor 301, a memory 302, and an interface 303. The processor 301 is a CPU, MPU, DSP, or the like. The memory 302 stores the processor's operating program, etc. The interface 303 communicates with the WMS1, WCS4, worker terminal 5, and DAS6.

[0016] The processor 301 of the WES3 realizes various functions by executing programs stored in the memory 302. For example, when the interface 303 receives an order list from the WMS1, the processor 301 acquires the order list. The processor 301 generates a transportation work plan from the order list. The processor 301 transmits the generated transportation work plan to the WCS4, the worker terminal 5, the DAS6, etc. via the interface 303. The interface 303 also receives processing results, including results of processing based on the transportation work plan, from the WCS4, the worker terminal 5, and the DAS6, and transmits the results to the WMS1. The processor 301 may also update the inventory management database in the memory 302 according to the transportation processing results.

[0017] The method for creating a transport operation plan based on the order list may be any common method, and a detailed description thereof will be omitted here. The transport operation plan includes information such as the destination position of the automated guided vehicle and the transport destination.

[0018] The WCS 4 can be configured with one or more general-purpose computers and includes a processor 401, a memory 402, and an interface 403. The processor 401 is a CPU, an MPU, a DSP, or the like. The processor 401 controls the automated guided vehicle 7 based on a program stored in the memory and a transportation operation plan transmitted from the WES 3.

[0019] The automated guided vehicle 7 is a robot that transports the shelf 8 under the control of the WCS 4. For example, the automated guided vehicle may be an AGV (Automated Guided Vehicle) or an AMR (Autonomous Mobile Robot). The automated guided vehicle 7 may also include a SLAM (Simultaneous Localization and Mapping) type AGV. The automated guided vehicle 7 operates based on control signals (picking instructions) from the WCS 4. For example, the automated guided vehicle 7 travels toward a designated loading position based on route information received from the WCS 4 and picks up the shelf 8 (POD) at the designated loading position. The automated guided vehicle 7 travels toward a designated unloading position and moves to the designated unloading position (e.g., a specified workstation). The automated guided vehicle 7 also returns the shelf 8 to the shelf storage area after the picking operation at the workstation is completed. The automated guided vehicle 7 may or may not unload the shelf 8 at the unloading position.

[0020] The shelves 8 are transportable objects that can be transported by the automated guided vehicle 7. The shelves 8 are capable of storing items such as merchandise, and are transportable objects that can be transported by the automated guided vehicle 7. For example, the shelves 8 may be POD shelves or the like.

[0021] The worker terminal 5 is a terminal carried by a worker. The worker terminal 5 can be configured with one or more general-purpose computers. The worker terminal 5 includes a processor 501, a memory 502, and an interface 503. The processor 501 is a CPU, an MPU, a DSP, or the like. The memory 502 stores the operating program of the processor 501, and the like. The interface 503 communicates with the WES3.

[0022] The worker terminal 5 is carried by a worker who works in the warehouse processing system 2. The worker terminal 5 may be any terminal that can be carried by a worker, such as a smartphone, tablet terminal, or wearable terminal. Although only one worker terminal 5 is shown in FIG. 1, it goes without saying that multiple worker terminals 5 corresponding to the number of workers may be connected to the WES 3.

[0023] The DAS 6 can be configured with one or more general-purpose computers. The DAS 6 includes a processor 601, a memory 602, and an interface 603. The processor 601 is a CPU, an MPU, a DSP, or the like. The memory 602 stores the operating program of the processor 601, and the like. The interface 603 communicates with the WES 3.

[0024] For example, the DAS 6 scans the barcode of an item picked from the shelf 8 by the picking means, and a lamp corresponding to the tray into which the scanned item is to be sorted lights up. When the DAS 6 has finished sorting the items onto the tray, the worker presses a switch located at the position of that tray, which determines that the work is complete. Then, the processor 601 creates a work log that indicates the work results (work performance), such as the work time. After creating the work log, the processor 601 supplies the created work log to the WES 3. Here, the picking means is a worker or a picking robot.

[0025] Next, the configuration of the automatic guided vehicle 7 according to the embodiment will be described. FIG. 2 is a diagram showing an example of the configuration of the automatic guided vehicle 7 in the embodiment. The automated guided vehicle 7 includes a processor 701, a ROM 702, a RAM 703, an auxiliary storage device 704, a communication interface 705, a sensor 706, a drive unit 707, a battery 708, a charging mechanism 709, tires 710, an elevator device 711, and a tilting stage 712. The elevator device 711 includes a pressure-sensitive element 7111, and the tilting stage 712 includes a rotation mechanism 7121 and a translation mechanism 7122.

[0026] The processor 701 has a function of controlling the overall operation of the automated guided vehicle 7. The processor 701 may also include an internal cache and various interfaces. The processor 701 performs various processes by executing programs stored in advance in the internal memory, the ROM 702, or the auxiliary storage device 704.

[0027] For example, the processor 701 is a CPU. The processor 701 may be realized by hardware such as an LSI, an ASIC, or an FPGA.

[0028] The processor 701 performs processing such as calculations and controls required for operations such as acceleration, deceleration, stopping, and direction changes. Based on control signals from the WCS 4, the processor 701 executes programs stored in the ROM 702 or the like to generate drive signals and output them to each unit.

[0029] For example, the WCS 4 transmits a control signal to move the automated guided vehicle 7 from its current position to a first position (shelf loading position) and then from the first position to a second position (storage / retrieval position). The WCS 4 also transmits a control signal to move the automated guided vehicle 7 from the second position to the first position. The processor 701 of the automated guided vehicle 7 outputs a drive signal in response to the control signal transmitted from the WCS 4. As a result, the automated guided vehicle 7 moves from its current position to the first position, from the first position to the second position, and from the second position to the first position.

[0030] Furthermore, the WCS 4 may transmit control signals all at once to move the automated guided vehicle 7 from its current position to a first position, from the first position to a second position, and from the second position to the first position. The control signal to move the automated guided vehicle 7 to the first position or the second position may be transmitted separately. For example, the WCS 4 may set at least one waypoint and transmit the control signal into a control signal to move the automated guided vehicle 7 to the waypoint and a control signal to move the automated guided vehicle 7 from the waypoint to the first position or the second position, and transmit each control signal to the automated guided vehicle 7.

[0031] The ROM 702 is a non-transitory computer-readable storage medium that stores the above-mentioned programs. The ROM 702 also stores data and various setting values ​​used by the processor 701 when performing various processes.

[0032] The RAM 703 is a memory used for reading and writing data, and is used as a so-called work area for storing data that is temporarily used when the processor 701 performs various processes.

[0033] The auxiliary storage device 704 is a non-transitory computer-readable storage medium and may store the above-mentioned programs. The auxiliary storage device 704 also stores data used by the processor 701 when performing various processes, data generated by the processes of the processor 701, various setting values, and the like.

[0034] The communication interface 705 is an interface for transmitting and receiving data to and from the WCS 4 etc. via a wireless LAN access point etc. For example, the communication interface 705 supports wireless LAN connection.

[0035] The sensor 706 is a plurality of reflective sensors. Each reflective sensor is attached around the periphery of the automated guided vehicle 7. Each reflective sensor emits a laser beam, detects the time it takes for the laser beam to be reflected by an object and return, detects the distance to the object based on the detected time, and notifies the processor 701 of a detection signal. The sensor 706 may also include a sensor capable of reading position information from a two-dimensional code placed on the floor.

[0036] The drive unit 707 is a motor or the like, and rotates or stops the motor based on a drive signal output from the processor 701. The power of the motor is transmitted to the tires 710 and then to the steering mechanism. The power from the motor moves the automated guided vehicle 7 to its destination.

[0037] Furthermore, the processor 701 operating as a self-position detection unit detects the current position of the automated guided vehicle 7 using the sensor 706 and images captured by a camera or the like. Then, the processor 701 transmits position information including the detected position, the direction of travel, etc. to the WCS 4.

[0038] The battery 708 supplies the necessary power to the drive unit 707 etc. The charging mechanism 709 is a mechanism that connects the charging station and the battery 708, and the battery 708 is charged with power supplied from the charging station etc. via the charging mechanism 709.

[0039] Next, the tires 710, the lifting device 711, and the tilt stage connected to the driving unit 707 will be described in detail. FIG. 3 is a diagram showing an example of the appearance and cross section of the automatic guided vehicle 7. As shown in FIG. FIG. 3(a) is a diagram showing an example of the appearance of the automatic guided vehicle 7, and FIG. 3(b) is a diagram showing an example of a cross section of the automatic guided vehicle 7.

[0040] 3, tires 710 are attached to the sides of the main body of the automatic guided vehicle 7. Furthermore, a tilting stage 712 is arranged inside the automatic guided vehicle 7, and an elevating device 711 is arranged on the tilting stage 712.

[0041] The lifting device 711 is a device that is raised and lowered by a drive unit 707 that is driven by a drive signal corresponding to an instruction to load or unload the shelf 8, which is included in a control signal from the processor 701. For example, when the automated guided vehicle 7 is under the shelf 8, the drive unit 707 rotates the motor (forward rotation) based on the drive signal output from the processor 701. The power from this motor raises the lifting device 711, lifting the shelf 8. After the automated guided vehicle 7 reaches its destination, the drive unit 707 rotates the motor (reverse rotation) based on the drive signal output from the processor 701. The power from this motor lowers the lifting device 711, and the shelf 8 is lowered to the floor.

[0042] As shown in FIG. 3, the lifting device 711 has a pressure-sensitive element 7111 disposed on the upper surface of the lifting device 711, that is, on the surface that holds the shelf 8. FIG. 4 is a diagram showing an example of the arrangement of the pressure-sensitive elements 7111 and an example of the measured intensity sensed by the pressure-sensitive elements 7111 when the shelf 8 is placed on the lifting device 711. As shown in Figures 3(a) and 4(a), the pressure-sensitive elements 7111 are elements that are uniformly attached to the upper surface of the lifting device 711. By arranging the pressure-sensitive elements 7111 uniformly on the upper surface of the lifting device 711, the pressure-sensitive elements 7111 can measure the weight of the shelf 8 two-dimensionally. The pressure-sensitive elements 7111 may be any elements that can measure the weight of the shelf 8. The pressure-sensitive elements 7111 output the measured intensity to the processor 701. The processor 701 calculates the position of the center of gravity of the shelf 8 based on this measured intensity. For example, the processor 701 calculates the position of the center of gravity of the shelf 8 by adding up the measured intensities.

[0043] Furthermore, when the shelf 8 is tilted, as shown in Fig. 4(b), the measurement intensity of the pressure-sensitive element 7111 is biased to one side, and the center of gravity position calculated by the processor 701 moves to the side where the shelf 8 is tilted. Therefore, the processor 701 of the automatic guided vehicle 7 can detect that the shelf 8 is tilted from the movement of the center of gravity position.

[0044] The tilting stage 712 is a stage that controls the tilt of the lifting device 711, i.e., the tilt of the shelf 8. The tilting stage 712 includes a rotation mechanism 7121 and a translation mechanism 7122. As shown in FIGS. 3 and 4 , the rotation mechanism 7121 is disposed below the lifting device 711, and the translation mechanism 7122 is disposed below the rotation mechanism 7121.

[0045] The rotation mechanism 7121 is a two-axis rotation mechanism having a rotation axis in the traveling direction, i.e., in front of the automatic guided vehicle 7, and a rotation axis in a direction perpendicular to the traveling direction. The rotation mechanism 7121 may also be a one-axis rotation mechanism having one rotation axis in the traveling direction of the automatic guided vehicle 7. The rotation mechanism 7121 is a mechanism for correcting the tilt of the lifting device 711 from the horizontal direction. The rotation mechanism 7121 may be any mechanism that can correct the tilt of the lifting device 711. For example, the rotation mechanism 7121 may be a mechanism that can tilt the tilting stage 712 by rotating the rotation mechanism 7121 using the drive unit 707 in accordance with instructions from the processor 701.

[0046] The translation mechanism 7122 is a mechanism capable of moving the lifting device 711 in the horizontal direction. For example, the translation mechanism 7122 corrects a deviation in the center of gravity of the shelf 8 held by the lifting device 711 by moving in the horizontal direction (e.g., the x direction and the y direction). The translation mechanism 7122 may be any mechanism capable of correcting the horizontal movement of the lifting device 711. For example, the translation mechanism 7122 may be any mechanism capable of moving the lifting device 711 in the horizontal direction. For example, the translation mechanism 7122 may be any mechanism capable of moving the lifting device 711 in the horizontal direction by the drive unit 707 in accordance with instructions from the processor 701, thereby moving the lifting device 711.

[0047] Next, the functions realized by the processor 701 will be described. The processor 701 has a function of receiving a transportation work plan transmitted by the WCS 4 via the communication interface 705. The transportation work plan includes information on the position of the shelf 8 to be transported by the automated guided vehicle 7, the position to which the shelf 8 should be transported, the weight of the item to be stored or removed by the work of the picking means, information on the return position of the shelf 8, etc.

[0048] The processor 701 has a function of moving the automated guided vehicle 7 to the shelf 8 based on the position information of the shelf 8 to be transported, which is included in the transport work plan. The processor 701 has a function of controlling the automated guided vehicle 7 to lift the shelf 8 after it has moved to the shelf 8.

[0049] The processor 701 has a function of obtaining the measurement results of the pressure-sensitive element 7111 after lifting the shelf 8. The processor 701 also has a function of calculating the weight and center of gravity position of the shelf 8 based on the measurement results. The method of calculating the weight and center of gravity position will be described later.

[0050] The processor 701 has a function of controlling the position of the center of gravity of the shelf 8 so as not to move in accordance with the position of the center of gravity of the shelf 8 while the shelf 8 is being transported. For example, when the automated guided vehicle 7 stops to change direction while moving the shelf 8, the processor 701 has a function of controlling the tilt stage 712 so as not to shift the position of the center of gravity of the shelf 8 due to the stop. For example, when the automated guided vehicle 7 starts or stops, the processor 701 has a function of controlling the tilt stage 712 so as to cancel out the inertial force associated with the shelf 8.

[0051] The processor 701 has a function to control the tilt stage 712 so that the shelf 8 does not tip over when the center of gravity is significantly shifted due to the application of an external force to the shelf 8, for example. Furthermore, when an external force is applied to the shelf 8, the processor 701 has a function to control the automated guided vehicle 7 to move in the direction of the applied external force so that the shelf 8 does not tip over. For example, when the automated guided vehicle 7 receives an external force due to contact with a worker, the processor 701 has a function to drive the drive unit 707, move in the direction of the applied external force, i.e., away from the worker, and then perform an emergency stop. Note that a method for determining whether an external force has been applied and a method for controlling the tilt stage 712 will be described later.

[0052] The processor 701 has a function of measuring the weight of an item carried into or out of the shelf 8 by the picking means during a storage or retrieval operation.

[0053] The processor 701 has a function of notifying the picking means of re-stacking information for performing the storing or retrieving operation again when the center of gravity position is shifted from the center of the lifting device 711 due to the storing or retrieving operation.

[0054] The processor 701 has a function to determine whether the weight of an item stored in or removed from the shelf 8 by a storing or removing operation meets the required weight based on the transportation work plan. If the required weight is not met, the processor 701 may have a function to notify the picking means.

[0055] (operation) Next, the flow of operations of the automatic guided vehicle 7 will be described using an example in which the order list is a warehousing order. FIG. 5 is a flowchart showing an example of the transport operation of the automatic guided vehicle 7 according to the embodiment. The operation of this flowchart is realized by the processor 701 of the automatic guided vehicle 7 reading and executing a program stored in a memory such as the ROM 702, RAM 703, or auxiliary storage device 704.

[0056] First, WMS1 receives an order list for storing items and transmits the order list to WES3. Processor 301 of WES3 generates a transport operation plan based on the order list and transmits the transport operation plan to WCS4. Processor 401 of WCS4 outputs the transport operation plan to the automated guided vehicle 7, thereby starting this flowchart. Note that while this flowchart explains the operation of the automated guided vehicle 7 in a storing operation, it is of course equally applicable to the operation of the automated guided vehicle 7 in an retrieval operation and an inventory operation.

[0057] In step S1, the processor 701 of the automated guided vehicle 7 receives a transportation work plan. The processor 701 receives the transportation work plan transmitted by the WCS 4 via the communication interface 705. Here, the transportation work plan includes information such as position information of the shelf 8 to which the automated guided vehicle 7 should transport, the destination of the shelf 8 (for example, the DAS 6 which is a workstation), weight information of the article to be stored on the shelf 8 in the warehousing work, and the destination of the article after the warehousing work (storage node position).

[0058] In step S2, the processor 701 controls the movement to the shelf 8. Here, the shelf 8 may be a POD or the like, and in the case of warehousing, the shelf 8 may be an empty shelf 8 that does not store any items. Conversely, in the case of warehousing, the shelf 8 may be a shelf 8 that stores items. Then, the processor 701 drives the drive unit 707 to raise the lifting device 711 and lift the shelf 8.

[0059] In step S3, the processor 701 measures the weight and center of gravity of the shelf 8 before it is stored. After lifting the shelf 8, the processor 701 receives the measurement results from the pressure-sensitive element 7111. The processor 701 then calculates the weight and center of gravity position of the shelf 8 based on the measurement results. For example, the processor 701 calculates the weight by adding up the measurement results of the pressure-sensitive elements 7111. Furthermore, the processor 701 calculates the center of gravity position of the shelf 8 based on the locations where the pressure-sensitive elements 7111 are respectively arranged and the measurement results.

[0060] In step S4, the processor 701 starts movement. The processor 701 drives the drive unit 707 to start movement of the shelf 8 to the destination.

[0061] In step S5, the processor 701 measures the position of the center of gravity of the shelf 8. As in step S3, the processor 701 calculates the position of the center of gravity of the shelf 8. Furthermore, the processor 701 may calculate the acceleration of the moving shelf 8 based on the measurement results of the pressure-sensitive element 7111. For example, the processor 701 may calculate the acceleration based on the movement of the position of the center of gravity.

[0062] In step S6, the processor 701 determines whether the shelf 8 is stationary or unsteady. For example, the center of gravity may move due to an external force (such as when the shelf 8 hits a person or another shelf 8). In these cases, the position of the center of gravity on the lifting device 711 will move over time. Therefore, the processor 701 determines whether the amount of movement of the center of gravity position over a predetermined time period exceeds a first threshold. Here, the first threshold is a predetermined value that is updated by machine learning, which will be described below, with a value determined by an administrator or the like as an initial value. If the processor 701 determines that the amount of movement exceeds the first threshold, the processor 701 determines that the shelf 8 is unsteady, that is, that there is a possibility that the shelf 8 may tip over. In this case, the process proceeds to step S7. On the other hand, if the processor 701 determines that the shelf 8 is stationary, the process proceeds to step S13.

[0063] In step S7, the processor 701 determines whether correction is possible using the tilting stage 712. The processor 701 determines whether correction is possible using the tilting stage 712 based on the center of gravity position measured in step S5. For example, the processor 701 determines whether the distance between the center of the lifting device 711 and the center of gravity of the shelf 8 is less than a second threshold. Here, the second threshold is a predetermined value determined based on the correction capabilities of the rotation mechanism 7121 and the translation mechanism 7122 of the tilting stage 712, etc. The second threshold is greater than the first threshold. If the processor 701 determines that the distance is less than the second threshold, it determines that control is possible using the tilting stage 712. Then, the process proceeds to step S12. On the other hand, if the distance is equal to or greater than the second threshold, the processor 701 determines that control is not possible using the tilting stage 712. Then, the process proceeds to step S8.

[0064] In step S8, the processor 701 moves the automated guided vehicle 7 forward and backward. The processor 701 drives the drive unit 707 to move the automated guided vehicle 7 forward and backward. For example, the processor 701 moves the automated guided vehicle 7 in the direction in which the position of the center of gravity has moved. For example, if the position of the center of gravity of the shelf 8 has shifted in the direction opposite to the traveling direction of the automated guided vehicle 7, that is, if an external force is being applied in the direction opposite to the traveling direction, the processor 701 controls the automated guided vehicle 7 to move in the opposite direction to the traveling direction, that is, to move backward. By controlling the automated guided vehicle 7 to move in the same direction as the external force is being applied, the processor 701 can prevent the shelf 8 from tipping over.

[0065] In step S9, the processor 701 controls the tilt stage 712. The processor 701 controls the rotation mechanism 7121 and translation mechanism 7122 of the tilt stage 712 so as to move the center of gravity of the shelf 8 toward the center of the lifting device 711.

[0066] FIG. 6 is a diagram showing an example of the operation of the tilt stage 712 when the center of gravity of the shelf 8 is shifted. FIG. 6 shows the appearance of an automated guided vehicle 7 transporting a shelf 8.

[0067] Fig. 6(a) is a diagram showing an example in which the automated guided vehicle 7 is transporting a shelf 8 in a steady state. Fig. 6(b) is a diagram showing an example in which an external force is applied to the shelf 8, causing the center of gravity of the shelf 8 to shift. Fig. 6(c) is a diagram showing an example of the operation of the tilt stage 712 when the center of gravity position is shifted due to an external force.

[0068] As shown in Figure 6(b), when an external force is applied from the direction of travel, as shown in Figure 6(c), the rotation mechanism 7121 is controlled to tilt toward the direction of travel and the translation mechanism 7122 is controlled to move in the opposite direction to the direction of travel, i.e., the side opposite to the side to which the external force was applied. In this way, the automated guided vehicle 7 is controlled to prevent the shelf 8 from tipping over. The amount of tilt may be an amount that prevents the legs of the shelf 8 from contacting the floor surface.

[0069] Note that steps S8 and S9 are operations aimed at preventing the shelf 8 from tipping over. Therefore, the processor 701 may perform steps S8 and S9 in reverse order, or may perform them simultaneously.

[0070] In step S10, the processor 701 controls the tilt stage 712. The processor 701 controls the rotation mechanism 7121 and the translation mechanism 7122 of the tilt stage 712 so as to move the center of gravity of the shelf 8 toward the center of the lifting device 711. The processor 701 controls the shelf 8 to prevent it from tipping over, in the same manner as described in step S9.

[0071] In step S11, the processor 701 stops the automated guided vehicle 7. In step S7, the automated guided vehicle 7 is stopped while controlling it to prevent the shelf 8 from tipping over in step S8 and step S9, or step S10. Then, the processor 701 sends an abnormal stop notification to the WCS 4, indicating that the center of gravity position has become unsteady due to an external force and the automated guided vehicle 7 has stopped.

[0072] In step S12, the processor 701 obtains a safety confirmation. The processor 401 of the WCS4 receives the abnormal stop notification and sends it to the WES3. The processor of the processor 301 of the WES3 controls the system to display and notify the manager of the abnormal stop notification. In response to the notification, the manager has the worker check the shelf 8 of the automated guided vehicle 7 that sent the abnormal stop notification. Then, if safety is confirmed, the manager inputs a safety confirmation into the WES3. The processor 301 of the WES3 notifies the WCS4 of the safety confirmation, and the processor 401 of the WCS4 notifies the automated guided vehicle 7 of the safety confirmation. After the automated guided vehicle 7 obtains the safety confirmation, the process returns to step S4. The processor 301 of the WES3 may also send an abnormal stop notification to the WMS1.

[0073] In step S13, the processor 701 controls the tilt stage 712. The processor 701 controls the tilt stage 712 so as not to shift the center of gravity of the shelf 8 in a steady state. That is, the control of the tilt stage 712 in step S13 is a control for preventing the center of gravity from moving from the center of the lifting device 711. For example, when the automated guided vehicle 7 stops, the processor 701 controls the tilt stage 712 so as to cancel out the inertial force caused by stopping or starting.

[0074] In step S14, the processor 701 determines whether the vehicle has arrived at the destination. It determines whether the vehicle has arrived at the destination specified in the storage instruction, for example, the DAS 6, which is a workstation. The processor 701 determines the position of the automated guided vehicle 7 using information read from a two-dimensional code attached to the floor or the sensor 706, etc., and determines whether the vehicle has arrived at the destination. If it is determined that the vehicle has not arrived at the destination, the process returns to step S4. On the other hand, if it is determined that the vehicle has arrived at the destination, the process proceeds to step S13. In step S15, the processor 701 ends the movement. After arriving at the destination, the processor 701 ends the movement. In this embodiment, the storage operation is performed without placing the shelf 8 on the floor.

[0075] 5, the operations of steps S4 to S15 are movement to the DAS 6, which is a workstation, that is, transportation processing of the shelf 8. Steps S16 to S20, which will be described below, are processing of the automated guided vehicle 7 in the warehousing operation.

[0076] In step S16, the processor 701 measures the weight. After the automated guided vehicle 7 stops moving, the picking means, which is a worker or a picking robot, starts storing the item. The processor 701 then measures the weight of the shelf 8 onto which the item is to be stored. The processor 701 subtracts the pre-operation weight, which is the weight of the shelf 8 before storage measured in step S3, from the measured post-operation weight to measure the amount of change in weight, i.e., the weight of the stored item.

[0077] In step S17, the processor 701 measures the position of the center of gravity. The processor 701 receives the measurement result via the pressure-sensitive element 7111. Then, similar to step S3, the processor 701 calculates the position of the center of gravity of the shelf 8 based on the measurement result.

[0078] In step S18, processor 701 determines whether the distance from the center of gravity position before warehousing to the center of gravity position shifted due to the warehousing operation is within a third threshold. The third threshold may be a predetermined value determined by a manager or the like. If it is determined that the distance is greater than the third threshold, the process proceeds to step S19. On the other hand, if it is determined that the distance is equal to or less than the third threshold, the process proceeds to step S20.

[0079] In step S19, the processor 701 transmits re-stacking information. The processor 701 generates re-stacking information indicating that the items received by the warehousing operation need to be re-stacking, and transmits the re-stacking information to the WCS 4. The processor 401 of the WCS 4 transmits the re-stacking information to the WES 3. The processor 301 of the WES 3 then transmits the re-stacking information to the operator terminal 5 or DAS 6 carried by the operator who is the picking means. The picking means will perform re-stacking based on the re-stacking information. Then, the process returns to step S17.

[0080] In step S20, processor 701 determines whether the required weight is met. Based on the weight information of the item included in the warehousing instruction, processor 701 determines whether the change measured in step S16 meets the required weight. If it is determined that the required weight is not met, the process returns to step S16. On the other hand, if it is determined that the required weight is met, the process proceeds to step S21.

[0081] Here, if the amount of change, i.e., the weight of the items received through picking work, does not meet the required weight during a predetermined period, the processor 701 may send a notification to the WCS 4 indicating that the predetermined weight is not met. The processor 401 of the WCS 4 then notifies the picking means of the notification via the WES 3. This allows the picking means to know if there are any items that have been missed or missed to be picked.

[0082] In step S21, the processor 701 controls movement to a storage node. The processor 701 controls the drive unit 707 to drive the unit 707 and move it to the shelf 8 that is the destination. During movement, the processor 701 performs the processes from step S5 to step S15 described above.

[0083] In step S22, the processor 701 records the measurement results. The processor 701 stores the measurement results, including information about the measured weight and center of gravity position, in the ROM 702, the RAM 703, or the auxiliary storage device 704. The processor 701 then transmits the measurement results to the WCS 4. The processor 401 of the WCS 4 then transmits the measurement results to the WES 3. The processor 701 then performs machine learning on the setting values ​​of the first threshold and the second threshold based on the measurement results. That is, the processor 701 uses machine learning to learn what range the steady-state range should be set to. The learned results are then reflected in the next transport. Here, the machine learning method may be any general supervised learning method, and therefore a detailed description thereof will be omitted here.

[0084] Furthermore, the processor 701 transmits the measurement results to the WCS 4. The processor 401 of the WCS 4 transmits the measurement results to the WES 3. Then, the processor 401 of the WCS 4 or the processor 301 of the WES 3 may perform machine learning based on the measurement results. The processor 701 of the automated guided vehicle 7 may then receive the results of the machine learning.

[0085] (Effects of the embodiment) According to the embodiment described above, pressure-sensitive elements 7111 are evenly arranged on the lifting device 711 of the automated guided vehicle 7, and the tilting stage 712 is arranged below the lifting device 711. These pressure-sensitive elements 7111 measure the weight and center of gravity of the shelf 8, and if the center of gravity is displaced, the tilting stage 712 is controlled to prevent the shelf 8 from tipping over. Furthermore, if the shelf 8 collides with a worker or the like and the center of gravity is displaced beyond a predetermined threshold, the processor 701 controls the automated guided vehicle 7 to move in the direction opposite to the displacement, thereby preventing the shelf 8 from tipping over.

[0086] Furthermore, the automated guided vehicle 7 measures the position of the center of gravity of the shelf 8 before warehousing, and then measures the position of the center of gravity of the shelf 8 after warehousing. This allows the automated guided vehicle 7 to check whether the position of the center of gravity of the shelf 8 has shifted due to warehousing. If the position of the center of gravity has shifted due to the warehousing operation, this shift is reported and the picking means is caused to re-stack the shelves, thereby preventing the shelf 8 from becoming unstable during transportation.

[0087] Furthermore, when an item is received, it is determined whether the required weight has been received. This allows the picking means to be notified if the item is received by mistake, thereby improving the accuracy of the work of the picking means.

[0088] [Other embodiments] In this embodiment, an example has been described in which the warehousing operation is performed without lowering the shelf 8 to the floor after arriving at the destination, but the automated guided vehicle 7 may place the shelf 8 on the floor after arriving at the destination. In this case, the processor 701 may drive the drive unit 707 to lower the lifting device 711 and place the shelf 8 on the floor. Then, after receiving an instruction from the WCS 4 that the warehousing operation is complete, the processor 701 may drive the drive unit 707 to raise the lifting device 711 and lift the shelf 8. The processor 701 may measure the weight and center of gravity when the shelf 8 is lifted, and determine whether the required weight is met or whether the shelf 8 needs to be re-stacked based on the measurement results.

[0089] The program according to this embodiment may be transferred in a state where it is stored in an electronic device (computer) such as the automated guided vehicle 7, or may be transferred in a state where it is not stored in an electronic device. In the latter case, the program may be transferred via a network, or may be transferred in a state where it is stored in a storage medium. The storage medium is a non-transitory tangible medium. The storage medium is a medium that can be read by a computer such as the automated guided vehicle 7 (computer-readable medium). The storage medium may be in any form, such as an optical disk (e.g., a CD-ROM), a magnetic disk, or a semiconductor memory (e.g., a memory card), as long as it is capable of storing a program and is readable by a computer.

[0090] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0091] S...Warehouse system 1. WMS 2. Warehouse processing system 3…WES 301...Processor 302...Memory 303...Interface 4. WMS 401...Processor 402...Memory 403...Interface 5...Worker terminal 501...processor 502...Memory 503...Interface 6…DAS 601...processor 602...Memory 603...Interface 7...Automated guided vehicle 701...Processor 702...ROM 703...RAM 704...Auxiliary storage device 705...Communication interface 706...Sensor 707...Drive unit 708...Battery 709…Charging mechanism 710...Tire 711...Lifting device 7111...Pressure-sensitive element 712...Tilt stage 7121...Rotation mechanism 7122…Translation mechanism 8…Shelf

Claims

1. An automated guided vehicle, an interface for receiving a transportation work plan; moving the automated guided vehicle to a position where the transported object is placed in accordance with the transport work plan, and then controlling a lifting device provided in the automated guided vehicle to lift the transported object; measuring a center of gravity position of the transported object based on a measurement result of a pressure-sensitive element disposed on an upper surface of the lifting device while the automated guided vehicle is being moved to a destination based on the transport operation plan; controlling the tilt of the tilt stage using a tilt stage equipped with a rotation mechanism having a rotation axis at least in the movement direction according to the measured center of gravity position; a processor; An unmanned guided vehicle equipped with

2. the processor determines whether the state is steady or unsteady based on the measured amount of movement of the center of gravity position, and if it determines that the state is unsteady, determines whether the amount of movement can be corrected by the tilt stage. The automated guided vehicle according to claim 1 .

3. When the processor determines that the amount of movement cannot be corrected by the tilt stage, the processor controls the automatic guided vehicle to move in a direction opposite to the direction in which the center of gravity position has moved.

3. The automated guided vehicle according to claim 2.

4. When the processor determines that the movement amount cannot be corrected by the tilt stage, the processor controls the tilt stage so that the transported object does not tip over.

3. The automated guided vehicle according to claim 2.

5. When the processor determines that the movement amount can be corrected by the tilt stage, the processor controls the tilt stage to prevent the transported object from tipping over.

3. The automated guided vehicle according to claim 2.

6. When it is determined that the state is steady, the processor controls the tilt stage so as to cancel out the inertial force acting on the automatic guided vehicle 7.

3. The automated guided vehicle according to claim 2.

7. The processor: After the movement based on the transport operation plan is completed, the measurement result of the center of gravity position is recorded in memory, updating a first threshold for determining whether the state is steady or unsteady by performing machine learning based on the measurement results stored in the memory; 3. The automated guided vehicle according to claim 2.

8. the tilt stage is disposed below the lifting device and includes a two-axis rotation mechanism further having a rotation axis in a direction perpendicular to the movement direction, and a translation mechanism is disposed below the two-axis rotation mechanism and is capable of moving the lifting device in a horizontal direction. The automated guided vehicle according to claim 1 .

9. The processor: After arriving at the destination, the center of gravity of the transported object is measured; determining whether a distance between a center of gravity position before a picking operation at the destination and a center of gravity position after the picking operation is within a predetermined threshold; If the predetermined threshold is not met, transmit re-stacking information indicating that the center of gravity position has shifted. The automated guided vehicle according to claim 1 .

10. The processor: After lifting the transported object, a pre-operation weight of the transported object is measured based on the measurement result of the pressure-sensitive element; After arriving at the destination, a post-work weight of the transported object is measured based on the measurement result of the pressure-sensitive element; calculating a change in weight due to the picking operation based on the post-operation weight and the pre-operation weight; determining whether a change in weight due to the picking operation is a predetermined weight based on the transportation operation plan; If the weight has not reached the predetermined weight, the weight of the transported object is measured again based on the measurement result of the pressure-sensitive element. The automated guided vehicle according to claim 1 .

11. the processor, when the amount of change does not satisfy the predetermined weight for the predetermined period, transmits a notification indicating that the predetermined weight is not satisfied. The automated guided vehicle according to claim 10.

12. An automated guided vehicle control method executed by a processor of the automated guided vehicle, comprising: receiving a transportation operation plan; moving the automated guided vehicle to a position where the transported object is placed in accordance with the transport operation plan, and then controlling a lifting device provided in the automated guided vehicle to lift the transported object; measuring a center of gravity position of the transported object based on a measurement result of a pressure-sensitive element disposed on an upper surface of the lifting device while the automated guided vehicle is being moved to the destination based on the transport operation plan; controlling the tilt of the tilt stage using a tilt stage equipped with a rotation mechanism having a rotation axis at least in the movement direction according to the measured center of gravity position; An automated guided vehicle control method comprising:

13. 1. An automated guided vehicle control program comprising instructions for execution by a processor of an automated guided vehicle, the instructions comprising: receiving a transportation operation plan; moving the automated guided vehicle to a position where the transported object is placed in accordance with the transport operation plan, and then controlling a lifting device provided in the automated guided vehicle to lift the transported object; measuring a center of gravity position of the transported object based on a measurement result of a pressure-sensitive element disposed on an upper surface of the lifting device while the automated guided vehicle is being moved to the destination based on the transport operation plan; controlling the tilt of the tilt stage using a tilt stage equipped with a rotation mechanism having a rotation axis at least in the movement direction according to the measured center of gravity position; An automated guided vehicle control program comprising:

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