Pallet detection device, pallet detection method, and pallet detection program

Abstract

This pallet detection device is provided with: an optical detector that outputs point-cloud data that is represented by two-dimensional coordinates, comprising an X-axis extending along a pallet transporter widthwise and a Y-axis orthogonal to the X-axis and extending along the pallet transporter lengthwise, and that correspond to a detected object; and a processing circuit. The processing circuit is configured so as to, if determining that a detected object is a pair of legs of the pallet: compute a first virtual point on the basis of first point-cloud data corresponding to one of the pair of legs; compute a second virtual point on the basis of second point-cloud data corresponding to the other of the pair of legs; and compute, as a target point toward which the pallet transporter should head, a midpoint of a line segment connecting the first virtual point and the second virtual point.

Description

Pallet detection device, pallet detection method, and pallet detection program

[0001] The present disclosure relates to a palette detection device, a palette detection method, and a palette detection program.

[0002] Patent Document 1 describes a device for detecting pallets. In this device, approximate position information regarding the approximate position of the pallet relative to a pallet carrier vehicle is first obtained. Next, detection light is projected from the pallet carrier vehicle onto a pair of legs of the pallet, and the reflected light of the detection light is received, thereby acquiring multiple detection data regarding the reflection points. Next, corner points, which are reflection points where the alignment direction of the point cloud data changes, are detected from the multiple detection data. Next, the point cloud data is divided into multiple groups separated by the corner points. Next, the multiple groups are classified into horizontal groups aligned in the width direction of the pallet or vertical groups aligned in the depth direction of the pallet based on the approximate position information. Finally, a centerline extending along the length of the pallet through the center of the width direction of the pallet is derived using the multiple detection data belonging to at least one of the vertical and horizontal groups.

[0003] Japanese Patent Application Laid-Open No. 2022-188455

[0004] In Patent Document 1, the processing is complicated because it is necessary to perform relatively complex calculations, such as classifying a plurality of pieces of detected data for each leg into vertical and horizontal groups.

[0005] The present disclosure aims to easily calculate a target point to which a carrier pallet vehicle should head in a pallet detection device.

[0006] A pallet detection device according to one aspect of the present disclosure is a device for detecting pallets, the pallet comprising a loading section on which heavy objects are loaded and a plurality of legs supporting the loading section, the plurality of legs including a pair of legs arranged at a longitudinal end of the pallet at a distance from each other in the width direction of the pallet, the device comprising: an optical detector that, when attached to a pallet carrier vehicle, receives light reflected by a detection object present around the pallet carrier vehicle and outputs point cloud data represented by two-dimensional coordinates including an X-axis extending along the width direction of the pallet carrier vehicle and a Y-axis perpendicular to the X-axis and extending along the longitudinal direction of the pallet carrier vehicle, and corresponds to the detection object; and a processing circuit connected to the optical detector, the processing circuit acquiring the point cloud data from the optical detector and determining, based on the point cloud data, whether the detection object is the pair of legs. If it is determined that the object to be detected is the pair of legs, a first virtual point is calculated in which the X coordinate of a first point in first point cloud data corresponding to one of the pair of legs in the point cloud data is closest to the other of the pair of legs in the X axis direction, and the Y coordinate of a second point in the first point cloud data is closest to the carrier pallet vehicle in the Y axis direction, as a first X coordinate; if it is determined that the object to be detected is the pair of legs, a second virtual point is calculated in which the X coordinate of a third point in second point cloud data corresponding to the other of the pair of legs in the X axis direction is closest to the one of the pair of legs in the X axis direction, and the Y coordinate of a fourth point in the second point cloud data is closest to the carrier pallet vehicle in the Y axis direction, as a second Y coordinate; and the midpoint of the line segment connecting the first virtual point and the second virtual point is calculated as a target point to which the carrier pallet vehicle should head.

[0007] A pallet detection method according to one aspect of the present disclosure is a method for detecting a pallet, the pallet comprising a loading section on which a heavy object is loaded and a plurality of legs supporting the loading section, the plurality of legs including a pair of legs arranged at an end of the longitudinal direction of the pallet at a distance from each other in a width direction of the pallet, the method comprising the steps of: acquiring point cloud data from an optical detector that, when attached to the pallet carrier vehicle, receives light reflected by a detection object present around the pallet carrier vehicle, the point cloud data being represented by two-dimensional coordinates including an X-axis extending along the width direction of the pallet carrier vehicle and a Y-axis orthogonal to the X-axis and extending along the longitudinal direction of the pallet carrier vehicle, and outputs point cloud data corresponding to the detection object; determining based on the point cloud data whether the detection object is the pair of legs; When it is determined that the object to be detected is a pair of legs, a first virtual point is calculated having, as a first X-coordinate, the X-coordinate of a first point in first point cloud data corresponding to one of the pair of legs that is closest to the other of the pair of legs in the X-axis direction, and a first Y-coordinate of a Y-coordinate of a second point in the first point cloud data that is closest to the carrier pallet vehicle in the Y-axis direction; when it is determined that the object to be detected is the pair of legs, a second virtual point is calculated having, as a second X-coordinate, the X-coordinate of a third point in second point cloud data corresponding to the other of the pair of legs that is closest to the one of the pair of legs in the X-axis direction, and a second Y-coordinate of a fourth point in the second point cloud data that is closest to the carrier pallet vehicle in the Y-axis direction; and calculating the midpoint of the line segment connecting the first virtual point and the second virtual point as a target point toward which the carrier pallet vehicle should head.

[0008] A palette detection program according to one aspect of the present disclosure causes a processor to execute the palette detection method. The program may be stored in a computer-readable storage medium. The storage medium is a non-transitory, tangible medium. The storage medium may be built into or external to a computer. Examples of computers include portable information terminals, personal computers, and servers. The storage medium may include RAM, ROM, EEPROM, and external storage devices. The storage medium may be, for example, a hard disk, flash memory, or optical disk. The program stored in the storage medium may be executed on a computer to which the storage medium is directly connected, or on a computer connected to the storage medium via a communications network. Examples of communications networks include a local area network (LAN) or the Internet.

[0009] According to one aspect of the present disclosure, a pallet detection device can easily calculate a target point to which a pallet carrier vehicle should head.

[0010] Fig. 1 is a schematic diagram of a pallet carrier vehicle and a pallet equipped with a pallet detection device according to an embodiment. Fig. 2 is a block diagram of a control system for the pallet carrier vehicle. Fig. 3 is a flowchart of processing performed by a processing circuit of the pallet detection device according to an embodiment. Fig. 4 is a schematic diagram showing point cloud data, a first virtual point, a second virtual point, and a midpoint as a target point. Fig. 5 is a schematic diagram showing a pallet carrier vehicle traveling toward a target point.

[0011] Hereinafter, embodiments will be described with reference to the drawings.

[0012] 1 is a schematic diagram of a carrier pallet car 2 and pallets 3 equipped with a pallet detection device 1 according to an embodiment. The pallet detection device 1 detects pallets 3 arranged around the carrier pallet car 2. The pallet detection device 1 includes a first computer 11 and at least one optical detector 18. Details of the first computer 11 and the at least one optical detector 18 will be described later.

[0013] The carrier pallet vehicle 2 includes a loading platform 20 and a plurality of tires 21 that support the loading platform 20. The loading platform 20 is capable of carrying a pallet 3. The plurality of tires 21 includes a plurality of pairs of tires 21. Each pair of the plurality of pairs of tires 21 is coupled to a separate axle 22. A hydraulic lifting cylinder 23 is individually provided between the loading platform 20 and each axle 22. The loading platform 20 is raised and lowered by the extension and contraction of each lifting cylinder 23.

[0014] The pallet 3 includes a loading section 40 on which a heavy object is loaded, and a plurality of legs 41 that support the loading section 40. The pallet 3 is defined by a longitudinal direction, a width direction, and a height direction that are perpendicular to one another. The height direction is perpendicular to the ground. The number of the legs 41 is, for example, 20. In this embodiment, each of the legs 41 is an H-shaped steel. Each leg 41 extends along the height direction so that a cross section perpendicular to the height direction has an H-shape. Each leg 41 is fixed to the loading section 40. The plurality of legs 41 includes a plurality of pairs of legs 41. Each pair of legs 41 is arranged at the same position as each other in the longitudinal direction of the pallet 3 and is arranged at a distance from each other in the width direction of the pallet 3. Each pair of legs 41 is arranged at a distance from each other in the longitudinal direction of the pallet 3. The plurality of pairs of legs 41 includes a pair of legs 41 arranged at the longitudinal ends of the pallet 3.

[0015] Figure 2 is a block diagram of the control system of the carrier pallet vehicle 2. Figure 2 shows an example in which the pallet detection device 1 is configured by a first computer 11 and the automatic driving control device 30 is configured by a second computer 31 different from the first computer 11, but the pallet detection device 1 and the automatic driving control device 30 may also be configured by a single computer. The carrier pallet vehicle 2 further includes the automatic driving control device 30, a satellite positioning receiver 24, an antenna 25, an engine 26, a switching valve 27, a braking device 28, and a steering device 29.

[0016] The automatic driving control device 30 receives position information from the satellite positioning receiver 24 via the antenna 25. The satellite positioning receiver 24 and the antenna 25 constitute part of a satellite positioning system. The satellite positioning system includes, for example, an RTK-GNSS (Real Time Kinematic-Global Navigation Satellite System) or a quasi-zenith satellite system. The automatic driving control device 30 adjusts the speed, acceleration, and deceleration of the pallet truck 2 by controlling the engine 26. The driving energy of the engine 26 is used to rotate the tires 21. The driving energy of the engine 26 is also used to drive a hydraulic pump connected to the lift cylinder 23 via a switching valve 27. The automatic driving control device 30 controls the switching valve 27 to extend and retract the lift cylinder 23, thereby raising and lowering the platform 20. The automatic driving control device 30 brakes the pallet truck 2 by controlling the braking device 28. The automatic driving control device 30 adjusts the steering angle of the carrier pallet vehicle 2 by controlling the steering device 29 .

[0017] Depending on the relative positional relationship between the carrier pallet vehicle 2 and the pallet 3, the automatic driving control device 30 may automatically drive the carrier pallet vehicle 2 with one longitudinal end of the carrier pallet vehicle 2 as the front end, or may automatically drive the carrier pallet vehicle 2 with the other longitudinal end of the carrier pallet vehicle 2 as the front end.

[0018] The automatic driving control system 30 includes a second computer 31. The second computer 31 is communicatively connected to the satellite positioning receiver 24, the engine 26, the braking device 28, and the steering device 29 via electric cables or wireless communication devices. The second computer 31 includes a processor 32, a system memory 33, a storage memory 34, and interfaces (I / F) 35 to 37. The processor 32 is, for example, a microcontrol unit (MPU) or a central processing unit (CPU). The processor 32 may be distributed across multiple processors. The system memory 33 is, for example, a RAM. The storage memory 34 is an example of a computer-readable medium and is a non-transitory, tangible medium. The storage memory 34 may include a ROM, an EEPROM, a hard disk, a flash memory, an optical disk, or a combination thereof.

[0019] The storage memory 34 stores an automatic driving control program PR2. The processor 32 reads the automatic driving control program PR2 from the storage memory 34 into the system memory 33 and executes it. The configuration in which the processor 32 executes the automatic driving control program PR2 read into the system memory 33 is an example of a processing circuit of the automatic driving control device 30. The second computer 31 can be an example of a processing circuit. Part or all of the automatic driving control program PR2 may be executed by a processing circuit of a server connected to the automatic driving control device 30 via a network.

[0020] The interface 35 receives position information received by the satellite positioning receiver 24 via the antenna 25. The interface 36 outputs drive commands generated by the processor 32 in accordance with the automatic driving control program PR2 to the engine 26, the braking device 28, and the steering device 29. The interface 37 is an I / O interface that receives data such as a target point TP (described later) output from the interface 16 of the pallet detection device 1.

[0021] The pallet detection device 1 includes a first computer 11 and at least one optical detector 18. In this embodiment, the at least one optical detector 18 includes a pair of optical detectors 18. The first computer 11 is communicatively connected to each of the pair of optical detectors 18 via an electrical cable or a wireless communication device. Each of the pair of optical detectors 18 has the same structure. The first computer 11 includes a processor 12, a system memory 13, a storage memory 14, and interfaces 15 and 16. The processor 12 is, for example, a microcontroller unit (MPU) or a central processing unit (CPU). The processor 12 may be distributed across multiple processors. The system memory 13 is, for example, a RAM. The storage memory 14 is an example of a computer-readable medium and is a non-transitory, tangible medium. The storage memory 14 may include a ROM, an EEPROM, a hard disk, a flash memory, an optical disk, or a combination thereof.

[0022] The storage memory 14 stores a pallet detection program PR1. The processor 12 reads the pallet detection program PR1 from the storage memory 14 into the system memory 13 and executes it. The configuration in which the processor 12 executes the pallet detection program PR1 read into the system memory 13 is an example of a processing circuit of the pallet detection device 1. The first computer 11 can be an example of a processing circuit. Part or all of the pallet detection program PR1 may be executed by a processing circuit of a server connected to the pallet detection device 1 via a network.

[0023] The interface 15 receives point cloud data PG corresponding to the detection target from each of the pair of optical detectors 18. The interface 16 is an I / O interface that outputs data such as target points TP (described later) calculated based on commands generated by the processor 12 in accordance with the pallet detection program PR1 to an interface 37 of the automatic driving control device 30. The interface 16 of the first computer 11 and the interface 37 of the second computer 31 are connected to each other so that they can communicate data with each other. The interface 16 of the first computer 11 and the interface 37 of the second computer 31 are connected to each other so that they can communicate with each other via an electric cable or a wireless communication device.

[0024] When attached to the carrier pallet car 2, each of the pair of optical detectors 18 receives light reflected by a detection target present around the carrier pallet car 2. One of the pair of optical detectors 18 is attached to one longitudinal end 2a of the carrier pallet car 2 and to a central portion 2b in the width direction of the carrier pallet car 2. The other of the pair of optical detectors 18 is attached to the other longitudinal end 2c of the carrier pallet car 2 and to a central portion 2d in the width direction of the carrier pallet car 2. For example, each of the pair of optical detectors 18 may be a 2D-LiDAR (Light Detection and Ranging) that can measure distances by scanning a laser beam in the horizontal direction.

[0025] Figure 3 is a flowchart of the processing performed by the processing circuit of the pallet detection device 1 according to this embodiment. Below, the steps of the method for detecting a pallet 3 by the pallet detection device 1 will be described according to the flow in Figure 3, with reference to Figures 1 and 2 as appropriate and primarily to Figure 4. The processor 12 executes the pallet detection program PR1 loaded into the system memory 13. For example, the processor 12 may operate only the optical detector 18 of the pair that is closest to the pallet 3 to be transported, in accordance with the position information of the pallet carrier vehicle 2 and the position information of the pallet 3.

[0026] 4 is a schematic diagram showing point cloud data PG, a first virtual point VP1, a second virtual point VP2, and a midpoint CP as a target point TP. First, the processor 12 acquires point cloud data PG corresponding to the detection target object from one optical detector 18 (step S1). The point cloud data PG is represented by two-dimensional coordinates including an X-axis extending along the width direction of the pallet vehicle 2 and a Y-axis perpendicular to the X-axis and extending along the length direction of the pallet vehicle 2. In this embodiment, the origin of the two-dimensional coordinates is set at the location of the optical detector 18.

[0027] The processor 12 may start acquiring the point cloud data PG from the time when the pallet carrier vehicle 2, traveling by automatic driving, is positioned within a predetermined range from the pallet 3 to be transported. The processor 12 may start acquiring the point cloud data PG before the pallet carrier vehicle 2 is positioned within the predetermined range from the pallet 3. The processor 12 may acquire the point cloud data PG at intervals of, for example, 20 milliseconds.

[0028] Next, the processor 12 determines whether the detection object is a pair of legs 41 of the pallet 3 based on the point cloud data PG acquired in step S1 (step S2). For example, the storage memory 14 stores data indicating the shape and dimensions of each of the pair of legs 41 of the pallet 3 and the spacing between the pair of legs 41. The processor 12 determines whether the detection object indicated by the point cloud data PG is a pair of legs 41 of the pallet 3 by, for example, performing pattern matching to compare the detection object indicated by the point cloud data PG with reference data stored in the storage memory 14. The processor 12 may perform filtering using a median filter on the point cloud data PG acquired in step S1 to remove noise before performing step S2. If the processor 12 does not determine in step S2 that the detection object is a pair of legs 41 of the pallet 3 (step S2: NO), the processor 12 returns to the procedure of step S1.

[0029] Next, when the processor 12 determines in step S2 that the detection object is a pair of legs 41 of the pallet 3 (step S2: YES), it calculates a first virtual point VP1 (step S3). The first virtual point VP1 is a virtual point whose first X coordinate is the X coordinate X1max of a first point P1 that is closest to the other of the pair of legs 41 in the X axis direction in the first point cloud data PG1 corresponding to one of the pair of legs 41 in the point cloud data PG, and whose first Y coordinate is the Y coordinate Y1min of a second point P2 that is closest to the pallet vehicle 2 in the Y axis direction in the first point cloud data PG1.

[0030] Next, the processor 12 calculates a second virtual point VP2 (step S4). The second virtual point VP2 is a virtual point whose second X coordinate is the X coordinate X2min of a third point P3 that is closest to one of the pair of legs 41 in the X axis direction in the second point cloud data PG2 corresponding to the other of the pair of legs 41 in the point cloud data PG, and whose second Y coordinate is the Y coordinate Y2min of a fourth point P4 that is closest to the pallet vehicle 2 in the Y axis direction in the second point cloud data PG2.

[0031] Next, the processor 12 calculates the midpoint CP of the line segment L connecting the first imaginary point VP1 calculated in step S3 and the second imaginary point VP2 calculated in step S4 as the target point TP toward which the pallet carrier vehicle 2 should head (step S5). In step S5, the processor 12 calculates the X coordinate of the midpoint CP by calculating the relational expression (X1max+X2min) / 2, and calculates the Y coordinate of the midpoint CP by calculating the relational expression (Y1min+Y2min) / 2.

[0032] Next, the processor 12 calculates the angle α of the Y axis with respect to the line segment L (step S6).

[0033] Finally, the processor 12 outputs the X and Y coordinates of the midpoint CP as the target point TP calculated in step S5 and the angle α calculated in step S6 to the automatic driving control device 30 (step S7). In step S7, the processor 12 may further output the point cloud data PG acquired in step S1 to the automatic driving control device 30.

[0034] Figure 5 is a schematic diagram showing the carrier pallet vehicle 2 traveling toward the target point TP. As shown in Figure 5, the automatic driving control device 30 automatically drives the carrier pallet vehicle 2 to travel so that the Y axis is perpendicular to the line segment L and the center of the carrier pallet vehicle 2 in the width direction is directed toward the target point TP, based on the X and Y coordinates of the target point TP and the angle α received from the pallet detection device 1. The automatic driving control device 30 automatically drives the carrier pallet vehicle 2 to travel toward the target point TP, with the lifting cylinder 23 retracted to lower the loading platform 20.

[0035] When the carrier pallet vehicle 2 approaches the target point TP and a pair of legs 41 goes out of the detection range of the optical detector 18, the optical detector 18 detects another pair of legs 41 adjacent to the pair of legs 41 in the longitudinal direction of the pallet 3, and can output the target point TP and angle α for the other pair of legs 41 to the automatic driving control device 30 using a procedure similar to steps S1 to S7. The automatic driving control device 30 can automatically drive the carrier pallet vehicle 2 toward the target point TP for the other pair of legs 41. By repeating the above procedure, the carrier pallet vehicle 2 properly enters below the pallet 3 while avoiding collision with the multiple legs 41 of the pallet 3.

[0036] Next, the automatic driving control device 30 extends the lifting cylinder 23 to raise the loading platform 20, thereby placing the pallet 3 on the loading platform 20. Next, the automatic driving control device 30 automatically drives the carrier pallet vehicle 2 to the location where the pallet 3 is to be transported. Finally, the automatic driving control device 30 retracts the lifting cylinder 23 at the location where the pallet 3 is to be transported, thereby lowering the loading platform 20, thereby placing the pallet 3 at the location where the pallet 3 is to be transported.

[0037] According to the configuration of this embodiment, a first virtual point VP1 is calculated based on the first point cloud data PG1 corresponding to one of the pair of legs 41 of the pallet 3, a second virtual point VP2 is calculated based on the second point cloud data PG2 corresponding to the other of the pair of legs 41 of the pallet 3, and the midpoint CP of the line segment L connecting the first virtual point VP1 and the second virtual point VP2 is calculated, thereby calculating the target point TP toward which the pallet carrier vehicle 2 should head. Therefore, the pallet detection device 1 can easily calculate the target point TP with a relatively simple calculation. Furthermore, the pallet detection device 1 can calculate the target point TP without depending on the distance between one of the pair of legs 41 and the other of the pair of legs 41. Furthermore, the pallet detection device 1 can calculate the target point TP without depending on the shape of each of the pair of legs 41.

[0038] Because the angle α of the Y-axis with respect to the line segment L connecting the first imaginary point VP1 and the second imaginary point VP2 is calculated, the automatic driving control device 30 can automatically drive the pallet vehicle 2 so that the Y-axis is perpendicular to the line segment L based on the angle α. This makes it possible to prevent the pallet vehicle 2 from tilting relative to the pallet 3 when viewed from above and below when the pallet vehicle 2 reaches the target point TP. This allows the pallet vehicle 2 to properly enter under the pallet 3. The automatic driving control device 30 may also bring the pallet vehicle 2 to an emergency stop if it determines that the angle α of the Y-axis with respect to the line segment L is greater than a threshold value. This makes it possible to avoid the pallet vehicle 2 colliding with the legs 41 of the pallet 3.

[0039] The optical detector 18 is attached to the longitudinal end of the carrier pallet vehicle 2 and the center of the width of the carrier pallet vehicle 2, and the origin of the two-dimensional coordinate system is set to the location point of the optical detector 18, so the pallet detection device 1 can easily calculate the target point TP to which the carrier pallet vehicle 2 should head.

[0040] Since the optical detector 18 includes a 2D-LiDAR, the pallet detection device 1 can detect point cloud data PG corresponding to a pair of legs 41 of the pallet 3 with a relatively inexpensive configuration.

[0041] In this embodiment, the optical detector 18 is described as being attached to the longitudinal end of the pallet car 2 and the center of the pallet car 2 in the width direction. The attachment position of the optical detector 18 is not limited to the position described in this embodiment, as long as it can properly detect detection targets present around the pallet car 2. For example, the optical detector 18 may be attached to the longitudinal end of the pallet car 2 and the center of the pallet car 2 in the width direction, or may be attached to another part of the pallet car 2. For example, the storage memory 14 may store data indicating the relative position of the optical detector 18 with respect to the longitudinal end of the pallet car 2 and the center of the pallet car 2 in the width direction. By using the data indicating the relative position, the origin of the two-dimensional coordinate system can be set to the longitudinal end of the pallet car 2 and the center of the pallet car 2 in the width direction, rather than the placement point of the optical detector 18, based on the data indicating the relative position.

[0042] In this embodiment, the pallet detection device 1 calculates the angle α of the Y-axis with respect to the line segment L, and the automatic driving control device 30 automatically drives the carrier pallet car 2 so that the Y-axis is perpendicular to the line segment L. However, the pallet detection device 1 may calculate the angle of the X-axis with respect to the line segment L, and the automatic driving control device 30 may automatically drive the carrier pallet car 2 so that the X-axis is parallel to the line segment L.

[0043] In this embodiment, the optical detector 18 includes a 2D-LiDAR. However, the optical detector 18 may include a laser range finder (LRF) instead of the 2D-LiDAR, as long as it can output point cloud data corresponding to detection targets present around the carrier pallet vehicle 2.

[0044] In this embodiment, the case where step S3 for calculating the first virtual point VP1 is performed and then step S4 for calculating the second virtual point VP2 is performed has been described based on the flowchart of Fig. 3. However, step S3 may be performed after step S4 is performed, or steps S3 and S4 may be performed in parallel.

[0045] In the present embodiment, the pallet detection device 1 is described as including a pair of optical detectors 18. However, one of the pair of optical detectors 18 may be omitted.

[0046] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0047] Each of the following aspects is a disclosure of a preferred embodiment. [Aspect 1] A device for detecting a pallet, wherein the pallet comprises a loading section on which a heavy object is loaded and a plurality of legs supporting the loading section, the plurality of legs including a pair of legs arranged at longitudinal ends of the pallet at a distance from each other in the width direction of the pallet, the device comprising: an optical detector that, when attached to a pallet carrier vehicle, receives light reflected by a detection object present around the pallet carrier vehicle and outputs point cloud data represented by two-dimensional coordinates including an X-axis extending along the width direction of the pallet carrier vehicle and a Y-axis perpendicular to the X-axis and extending along the longitudinal direction of the pallet carrier vehicle, and corresponds to the detection object; and a processing circuit connected to the optical detector, wherein the processing circuit acquires the point cloud data from the optical detector and determines whether the detection object is the pair of legs based on the point cloud data. a pallet detection device configured to calculate, when it is determined that the object to be detected is the pair of legs, a first virtual point having, as its first X coordinate, the X coordinate of a first point in first point cloud data corresponding to one of the pair of legs in the point cloud data that is closest to the other of the pair of legs in the X axis direction, and a first Y coordinate of a Y coordinate of a second point in the first point cloud data that is closest to the pallet vehicle in the Y axis direction; when it is determined that the object to be detected is the pair of legs, a second virtual point having, as its second X coordinate, the X coordinate of a third point in second point cloud data corresponding to the other of the pair of legs in the X axis direction, and a second Y coordinate of a fourth point in the second point cloud data that is closest to the pallet vehicle in the Y axis direction; and to calculate the midpoint of the line segment connecting the first virtual point and the second virtual point as a target point to which the pallet vehicle should head. [Aspect 2] The pallet detection device according to aspect 1, wherein the processing circuitry is configured to calculate an angle of the X-axis or the Y-axis relative to the line segment.[Aspect 3] The pallet detection device according to Aspect 1 or 2, wherein the optical detector is attached to an end of the carrier pallet car in the longitudinal direction and to the center of the carrier pallet car in the width direction, and the origin of the two-dimensional coordinate system is set to the arrangement point of the optical detector. [Aspect 4] The pallet detection device according to any one of Aspects 1 to 3, wherein the optical detector includes a 2D-LiDAR (Light Detection and Ranging) that can measure distances by scanning a laser beam in the horizontal direction.[Aspect 5] A method for detecting a pallet, wherein the pallet comprises a loading section on which a heavy object is loaded and a plurality of legs supporting the loading section, the plurality of legs including a pair of legs arranged at longitudinal ends of the pallet at a distance from each other in the width direction of the pallet, the method comprising: acquiring point cloud data from an optical detector that, when attached to the pallet carrier vehicle, receives light reflected by a detection object present around the pallet carrier vehicle, and outputs point cloud data represented by two-dimensional coordinates including an X-axis extending along the width direction of the pallet carrier vehicle and a Y-axis perpendicular to the X-axis and extending along the longitudinal direction of the pallet carrier vehicle, and that corresponds to the detection object; determining whether the detection object is the pair of legs based on the point cloud data; A pallet detection method comprising: when it is determined that the detection object is the pair of legs, calculating a first virtual point having as its first X coordinate the X coordinate of a first point in first point cloud data corresponding to one of the pair of legs in the point cloud data that is closest to the other of the pair of legs in the X axis direction and as its first Y coordinate the Y coordinate of a second point in the first point cloud data that is closest to the pallet vehicle in the Y axis direction; when it is determined that the detection object is the pair of legs, calculating a second virtual point having as its second X coordinate the X coordinate of a third point in second point cloud data corresponding to the other of the pair of legs in the point cloud data that is closest to the one of the pair of legs in the X axis direction and as its second Y coordinate the Y coordinate of a fourth point in the second point cloud data that is closest to the pallet vehicle in the Y axis direction; and calculating the midpoint of the line segment connecting the first virtual point and the second virtual point as a target point to which the pallet vehicle should head. [Aspect 6] A pallet detection program that causes a processor to execute the pallet detection method described in Aspect 5.

[0048] REFERENCE SIGNS LIST 1 Pallet detection device 2 Carrier pallet vehicle 3 Pallet 12 Processor 18 Optical detector 40 Loading section 41 Leg PG Point cloud data PG1 First point cloud data PG2 Second point cloud data P1-4 First to fourth points TP Target point CP Midpoint VP1, 2 First and second virtual points L Line segment α Angle PR1 Pallet detection program

Claims

1. A device for detecting pallets, wherein the pallet comprises a loading section on which a heavy object is loaded and a plurality of legs supporting the loading section, the plurality of legs including a pair of legs arranged at an end of the longitudinal direction of the pallet with a gap between them in the width direction of the pallet, the device comprising: an optical detector which, when attached to a pallet carrier vehicle, receives light reflected by a detection object present around the pallet carrier vehicle and outputs point cloud data represented by two-dimensional coordinates including an X axis extending along the width direction of the pallet carrier vehicle and a Y axis perpendicular to the X axis and extending along the longitudinal direction of the pallet carrier vehicle, and which corresponds to the detection object; and a processing circuit connected to the optical detector, wherein the processing circuit acquires the point cloud data from the optical detector and determines whether the detection object is the pair of legs based on the point cloud data, a pallet detection device configured to calculate, when it is determined that the object to be detected is the pair of legs, a first virtual point having, as its first X coordinate, the X coordinate of a first point in first point cloud data corresponding to one of the pair of legs in the point cloud data that is closest to the other of the pair of legs in the X axis direction, and a first Y coordinate of a Y coordinate of a second point in the first point cloud data that is closest to the pallet vehicle in the Y axis direction; when it is determined that the object to be detected is the pair of legs, a second virtual point having, as its second X coordinate, the X coordinate of a third point in second point cloud data corresponding to the other of the pair of legs in the X axis direction, and a second Y coordinate of a fourth point in the second point cloud data that is closest to the pallet vehicle in the Y axis direction; and to calculate the midpoint of the line segment connecting the first virtual point and the second virtual point as a target point to which the pallet vehicle should head.

2. The pallet detection device of claim 1, wherein the processing circuitry is configured to calculate the angle of the X-axis or the Y-axis relative to the line segment.

3. A pallet detection device as described in claim 1 or 2, wherein the optical detector is attached to the longitudinal end of the carrier pallet car and the center of the width of the carrier pallet car, and the origin of the two-dimensional coordinate system is set at the location point of the optical detector.

4. A pallet detection device according to any one of claims 1 to 3, wherein the optical detector includes a 2D-LiDAR (Light Detection and Ranging) that can measure distances by scanning a laser beam horizontally.

5. A method for detecting a pallet, wherein the pallet comprises a loading section on which a heavy object is loaded and a plurality of legs supporting the loading section, the plurality of legs including a pair of legs arranged at an end of the longitudinal direction of the pallet with a gap between them in the width direction of the pallet, the method comprising: acquiring point cloud data from an optical detector that, when attached to a pallet carrier vehicle, receives light reflected by a detection object present around the pallet carrier vehicle, and outputs point cloud data represented by two-dimensional coordinates including an X-axis extending along the width direction of the pallet carrier vehicle and a Y-axis perpendicular to the X-axis and extending along the longitudinal direction of the pallet carrier vehicle, and that corresponds to the detection object; and determining whether the detection object is the pair of legs based on the point cloud data. a pallet detection method comprising: when it is determined that the detection object is the pair of legs, calculating a first virtual point having, as a first X coordinate, the X coordinate of a first point in first point cloud data corresponding to one of the pair of legs in the point cloud data that is closest to the other of the pair of legs in the X axis direction, and a first Y coordinate of a Y coordinate of a second point in the first point cloud data that is closest to the pallet vehicle in the Y axis direction; when it is determined that the detection object is the pair of legs, calculating a second virtual point having, as a second X coordinate, the X coordinate of a third point in second point cloud data corresponding to the other of the pair of legs in the point cloud data that is closest to the one of the pair of legs in the X axis direction, and a second Y coordinate of a fourth point in the second point cloud data that is closest to the pallet vehicle in the Y axis direction; and calculating a midpoint of a line segment connecting the first virtual point and the second virtual point as a target point to which the pallet vehicle should head.

6. A palette detection program that causes a processor to execute the palette detection method according to claim 5.

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