forklift

Abstract

To provide a forklift capable of suppressing the contact of a fork with a palette until a fork is completed to be inserted into a palette.SOLUTION: A forklift comprises a fork, an external sensor, and a control device. The external sensor detects an object position with the coordinates in a three-dimensional coordinates system. The control device acquires point group data from the external sensor. The point group data is a set of the points indicating a defined surface to define an insertion hole of a palette. The control device derives a relative distance between the fork and the insertion hole in the direction perpendicular to the direction that the fork and the palette face each other, and a relative angle between the fork and the insertion hole with respect to the direction that the fork and the palette face each other, from the point group data. The control device adjusts the fork position so that the fork does not contact with the palette during inserting the fork into the insertion hole based on the relative distance and the relative angle.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a forklift. [Background technology]

[0002] The forklift includes a fork and a control device. The forklift loads a pallet onto the fork. When loading the pallet onto the fork, the fork is inserted into an insertion hole of the pallet, and then the fork is raised. If the fork comes into contact with the pallet during the process of inserting the fork into the insertion hole, the pallet may not be loaded smoothly. For this reason, the control device aligns the fork before inserting the fork into the insertion hole. The forklift described in Patent Document 1 derives the amount of inclination of the pallet based on the shape and dimensions of the insertion hole. The insertion hole is the opening of the insertion hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-156641 A Summary of the Invention [Problem to be solved by the invention]

[0004] When aligning the forks, the position and inclination of the forks are adjusted. As in Patent Document 1, the position and inclination of the pallet are detected based on the shape and dimensions of the insertion hole, so that the forks are aligned so that the forks and the insertion hole face each other and the inclinations of the forks and the pallet match. However, even when the forks are aligned, there is a risk that the forks and the pallet may come into contact with each other before the forks are completely inserted into the insertion holes. [Means for solving the problem]

[0005] A forklift that solves the above problem includes a fork, an external sensor that detects the position of an object in coordinates of a three-dimensional coordinate system, and a control device, and the control device obtains point cloud data, which is a set of points that represent the position of a definition plane that defines the insertion hole of a pallet, from the external sensor, derives from the point cloud data a relative distance between the fork and the insertion hole in a direction perpendicular to the direction in which the fork and the pallet face each other, and a relative angle between the fork and the insertion hole with respect to the direction in which the fork and the pallet face each other, and adjusts the position of the fork based on the relative distance and relative angle so that the fork and the pallet do not come into contact while the fork is being inserted into the insertion hole.

[0006] The point cloud data is a set of points that represent the position of the demarcation plane. It is the demarcation plane that the fork may come into contact with during the process of inserting the fork into the insertion hole. By deriving the relative distance between the fork and the insertion hole and the relative angle between the fork and the insertion hole from the point cloud data, it is possible to derive the relative distance and relative angle according to the amount of insertion of the fork. Then, by adjusting the position of the fork based on this relative distance and relative angle, it is possible to adjust the position of the fork while it is being inserted into the insertion hole. Even while the fork is being inserted, the position of the fork can be adjusted so that the fork and the pallet do not come into contact with each other, so it is possible to prevent the fork and the pallet from coming into contact with each other until the insertion of the fork is completed.

[0007] Regarding the above-mentioned forklift, the forklift may be equipped with a memory device that stores a point cloud map, which is a collection of points that represent the position of the demarcation plane when the fork and the pallet are not in contact, in coordinates of the three-dimensional coordinate system, and the control device may derive the relative distance from a distance difference of the point cloud data with respect to the point cloud map, and derive the relative angle from an inclination of the point cloud data with respect to the point cloud map.

[0008] Regarding the forklift described above, the forklift may be equipped with a storage device, and the storage device may store a point cloud map which is a set of points representing the positions of the demarcation plane when the fork and the pallet are not in contact, in coordinates of the three-dimensional coordinate system. The control device may detect a plane from the point cloud map, detect a plane identical to the plane from the point cloud data, derive the relative distance from a distance difference between the plane detected from the point cloud map and the plane detected from the point cloud data, and derive the relative angle from a tilt of the plane detected from the point cloud data relative to the plane detected from the point cloud map. Effect of the Invention

[0009] According to the present invention, it is possible to prevent the forks from coming into contact with the pallet until the forks have been completely inserted. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram illustrating a truck and a forklift. [Diagram 2] FIG. 2 is a front view of a pallet loaded on a loading platform of the truck of FIG. 1. [Diagram 3] FIG. 3 is a perspective view of the pallet of FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view of the pallet of FIG. 2. [Diagram 5] FIG. 2 is a side view of a forklift operating in the area of ​​FIG. 1. [Figure 6] FIG. 6 is a perspective view of a cargo handling device provided on the forklift of FIG. 5. [Figure 7] FIG. 6 is a schematic diagram of the forklift shown in FIG. 5. [Figure 8] FIG. 6 is a diagram showing an example of a point cloud map stored in an auxiliary storage device included in the forklift of FIG. 5. [Figure 9] 5 is a flowchart showing a processing procedure of alignment control in the first embodiment. [Figure 10] 10 is a flowchart showing a processing procedure of alignment control according to the second embodiment. [Figure 11] 13 is a flowchart showing a processing procedure of alignment control in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] (First embodiment) A first embodiment of the forklift will be described. As shown in FIG. 1, a truck 10 is parked in area A1. The truck 10 has a loading platform 11. A pallet 20 is loaded on the loading platform 11 of the truck 10. Area A1 is, for example, the whole or part of a location such as a factory, a port, an airport, a commercial facility, or a public facility. A forklift 40 is in operation in area A1. The forklift 40 unloads the pallet 20 loaded onto the truck 10. After unloading, the forklift 40 transports the pallet 20 to another location or another device.

[0012] 2, the pallet 20 is a flat pallet. The pallet 20 includes a first wall portion 21, a second wall portion 24, and beams 27 and 29. As shown in FIG. 3, the first wall portion 21 and the second wall portion 24 are plate-shaped. The first wall portion 21 and the second wall portion 24 are rectangular. The first wall portion 21 and the second wall portion 24 face each other. The first wall portion 21 has a first outer surface 22 and a first inner surface 23. The first outer surface 22 and the first inner surface 23 are surfaces that are opposite to each other in the thickness direction of the first wall portion 21. The second wall portion 24 has a second outer surface 25 and a second inner surface 26. The second outer surface 25 and the second inner surface 26 are surfaces that are opposite to each other in the thickness direction of the second wall portion 24. The first inner surface 23 of the first wall portion 21 and the second inner surface 26 of the second wall portion 24 face each other. The first outer surface 22, the first inner surface 23, the second outer surface 25, and the second inner surface 26 are parallel to each other.

[0013] The beams 27, 29 are provided between the first wall portion 21 and the second wall portion 24. The beams 27, 29 include a first beam 27 and a second beam 29. Four first beams 27 are provided. One first beam 27 is provided at each of the four corners of the pallet 20. Four second beams 29 are provided. One second beam 29 is provided between each of the first beams 27. The first beam 27 has a first surface 28. The first surface 28 is a surface facing the second beam 29. The first beam 27 has two first surfaces 28. The second beam 29 has a second surface 30. The second surface 30 is a surface facing the first beam 27. The second beam 29 has two second surfaces 30. The first surface 28 and the second surface 30 face each other.

[0014] The area surrounded by the first inner surface 23, the second inner surface 26, the first surface 28, and the second surface 30 is the insertion hole 31. The first inner surface 23, the second inner surface 26, the first surface 28, and the second surface 30 are defining surfaces that define the insertion hole 31.

[0015] As shown in FIG. 4 , the first wall portion 21 has a first through hole defining surface 32. The first through hole defining surface 32 extends between the first outer surface 22 and the first inner surface 23. The first through hole defining surface 32 is an annular surface. The area surrounded by the first through hole defining surface 32 is the first through hole 33. The first through hole defining surface 32 defines the first through hole 33. The first through hole 33 penetrates the first wall portion 21.

[0016] The second wall portion 24 includes a second through hole defining surface 34. The second through hole defining surface 34 extends between the second outer surface 25 and the second inner surface 26. The second through hole defining surface 34 is an annular surface. The area surrounded by the second through hole defining surface 34 is the second through hole 35. The second through hole defining surface 34 defines the second through hole 35. The second through hole 35 penetrates the second wall portion 24.

[0017] 5, the forklift 40 includes a driving wheel 41, a steering wheel 42, a loading device 43, and an external sensor 61. The loading device 43 includes a mast 44, a lift bracket 47, two forks 48, a lift cylinder 51, and a tilt cylinder 52.

[0018] The mast 44 includes an outer mast 45 and an inner mast 46. The inner mast 46 is provided so as to be capable of ascending and descending relative to the outer mast 45. The lift bracket 47 is attached to the inner mast 46. The fork 48 is attached to the lift bracket 47. The lift bracket 47 and the fork 48 can be raised and lowered together with the inner mast 46.

[0019] The forks 48 include insertion portions 49. The insertion portions 49 extend from the lift brackets 47 toward the front of the forklift 40. The insertion portions 49 are inserted into the insertion holes 31 when the pallet 20 is loaded onto the forks 48. The insertion portions 49 include an upper surface 50.

[0020] The lift cylinder 51 raises and lowers the inner mast 46. The tilt cylinder 52 tilts the mast 44 in the front-rear direction of the forklift 40. The lift cylinder 51 and the tilt cylinder 52 are hydraulic cylinders.

[0021] 6, the external sensor 61 is provided between the two forks 48 in the vehicle width direction of the forklift 40. The external sensor 61 is provided so as to rise and fall together with the forks 48. In this embodiment, the external sensor 61 is provided on the lift bracket 47.

[0022] The external sensor 61 detects the position of an object by coordinates in a three-dimensional coordinate system. The external sensor 61 is provided to acquire the coordinates of the first inner surface 23, the second inner surface 26, the first surface 28, and the second surface 30 in the three-dimensional coordinate system. The external sensor 61 is provided so as to acquire the coordinates of at least one of the first inner surface 23, the second inner surface 26, the first surface 28, and the second surface 30 even when the insertion portion 49 is inserted into the insertion hole 31. For example, a millimeter wave radar, a ToF (Time of Flight) camera, and a LIDAR (Laser Imaging Detection and Ranging) can be used as the external sensor 61. When no object exists in the depth, such as the insertion hole 31 of the pallet 20, the detection accuracy of the coordinates may decrease with a stereo camera. For this reason, it is preferable to use a sensor that utilizes reflection, such as reflected light of a laser or reflected waves of an electric wave, as the external sensor 61.

[0023] In this embodiment, a LIDAR is used as the external sensor 61. The external sensor 61 irradiates the surroundings with a laser and receives the reflected light reflected from the point where the laser hits, thereby deriving the distance to the point. The point where the laser hits represents a part of the surface of the object. The position of the point can be expressed by the coordinates of a polar coordinate system. The coordinates of the point in the polar coordinate system are converted to the coordinates of a Cartesian coordinate system. The external sensor 61 derives the coordinates of the point in the sensor coordinate system. The sensor coordinate system is a three-dimensional coordinate system with the external sensor 61 as the origin. The sensor coordinate system is a three-axis Cartesian coordinate system and includes an X axis, a Y axis, and a Z axis. The direction in which the X axis extends coincides with the vehicle width direction of the forklift 40. When the loading device 43 is not tilted, the direction in which the Y axis extends coincides with the front-rear direction of the forklift 40. When the loading device 43 is not tilted, the direction in which the Z axis extends coincides with the vertical direction. When inserting the insertion portion 49 into the insertion hole 31, the forklift 40 moves forward with the pallet 20 positioned in front of the forklift 40. The direction in which the Y axis extends is the direction in which the forks 48 and the pallet 20 face each other. In Figures 1, 5, and 6, the X-axis of the sensor coordinate system is indicated by arrow X, the Y-axis is indicated by arrow Y, and the Z-axis is indicated by arrow Z.

[0024] As shown in FIG. 7, the forklift 40 includes a load sensor 62, a drive mechanism 63, a hydraulic mechanism 64, a control device 65, and an auxiliary storage device 68. The loading sensor 62 is a sensor for detecting that a pallet 20 is loaded on the fork 48. The loading sensor 62 is provided, for example, at the base end of the insertion portion 49. When the forklift 40 picks up the pallet 20, the insertion portion 49 is inserted into the insertion hole 31. As the insertion portion 49 is inserted into the insertion hole 31, the pallet 20 approaches the base end of the insertion portion 49. As a result, when the insertion portion 49 is inserted into the insertion hole 31 by a predetermined amount or more, the loading sensor 62 detects that the pallet 20 is loaded on the fork 48. The predetermined amount is the distance from the tip of the insertion portion 49 to the loading sensor 62.

[0025] The drive mechanism 63 is a member for causing the forklift 40 to travel, and includes a travel motor for driving the drive wheels 41 and a steering mechanism for steering the steering wheels 42. The hydraulic mechanism 64 is a member for controlling the supply and discharge of hydraulic oil to the lift cylinder 51 and the tilt cylinder 52, and includes a cargo motor for driving a pump and a control valve. The inner mast 46 is raised and lowered by the supply and discharge of hydraulic oil to the lift cylinder 51. The mast 44 is tilted in the front-to-rear direction of the forklift 40 by the supply and discharge of hydraulic oil to the tilt cylinder 52. The raising and lowering of the inner mast 46 can also be referred to as the raising and lowering of the forks 48. The tilting of the mast 44 can also be referred to as the tilting of the forks 48.

[0026] The control device 65 includes a processor 66 and a storage unit 67. The storage unit 67 includes a random access memory (RAM) and a read only memory (ROM). The storage unit 67 stores program codes or instructions configured to cause the processor 66 to execute processes. The storage unit 67, i.e., the computer-readable medium, includes any available medium accessible by a general-purpose or special-purpose computer. The control device 65 may be configured by a hardware circuit such as an ASIC or an FPGA. The control device 65, which is a processing circuit, may include one or more processors that operate according to a computer program, one or more hardware circuits such as an ASIC or an FPGA, or a combination thereof.

[0027] The control device 65 controls the drive mechanism 63 and the hydraulic mechanism 64. The forklift 40 is an automatically operated forklift that travels and handles cargo under the control of the control device 65.

[0028] The auxiliary storage device 68 stores information that can be read by the control device 65. Examples of the auxiliary storage device 68 include a hard disk drive and a solid state drive.

[0029] The auxiliary storage device 68 stores a point cloud map M1. As shown in Fig. 8, the point cloud map M1 is a collection of points P1 that represent the interior of the pallet 20 by coordinates in the sensor coordinate system. The point cloud map M1 shown in Fig. 8 is a point cloud map M1 that corresponds to the cross section of the pallet 20 shown in Fig. 4. For ease of explanation, the point cloud map M1 shown in Fig. 8 illustrates a point P1 that corresponds to the cross section of the pallet 20, but the point cloud map M1 is a collection of points P1 obtained at a predetermined interval over the entire defined surface. The auxiliary storage device 68 is a storage device.

[0030] The point cloud map M1 is data that expresses the positions of the first inner surface 23, the second inner surface 26, the first surface 28, and the second surface 30 in coordinates of a sensor coordinate system. The point cloud map M1 is the coordinates of a point P1 in the sensor coordinate system acquired in a state where the relative distance between the fork 48 and the insertion hole 31 is 0 and the relative angle between the fork 48 and the insertion hole 31 is 0. The state where the relative distance between the fork 48 and the insertion hole 31 is 0 and the relative angle between the fork 48 and the insertion hole 31 is 0 means that when the forklift 40 and the pallet 20 face each other and the forklift 40 is moved forward, the fork 48 is inserted into the insertion hole 31 without contacting the pallet 20. In the following description, the relative distance between the fork 48 and the insertion hole 31 is referred to as the relative distance, and the relative angle between the fork 48 and the insertion hole 31 is referred to as the relative angle.

[0031] The relative distance is the amount of deviation between the position of the fork 48 and the insertion hole 31 on the XZ plane of the sensor coordinate system. The XZ plane is a plane defined by the X axis of the sensor coordinate system and the Z axis of the sensor coordinate system. When the center position of the tip of the fork 48 on the XZ plane coincides with the center position of the insertion hole 31 on the XZ plane, the relative distance is 0. When the relative distance is 0, there is a clearance between the fork 48 and the demarcation surface on the XZ plane. The XZ plane is a plane that extends in a direction perpendicular to the direction in which the fork 48 and the pallet 20 face each other. The relative distance can be said to be the relative distance between the fork 48 and the insertion hole 31 in the direction perpendicular to the direction in which the fork 48 and the pallet 20 face each other.

[0032] The relative angle is the deviation between the inclination of the fork 48 with respect to the Y axis and the inclination of the insertion hole 31 with respect to the Y axis. The inclination of the fork 48 with respect to the Y axis is the angle between the top surface 50 of the fork 48 and the Y axis. The inclination of the insertion hole 31 with respect to the Y axis is the angle between the first inner surface 23 of the pallet 20 and the Y axis. The first inner surface 23, the second inner surface 26, the first outer surface 22, and the second outer surface 25 are parallel to each other. Therefore, the inclination of the insertion hole 31 with respect to the Y axis can also be said to be the inclination of the second inner surface 26, the first outer surface 22, and the second outer surface 25 with respect to the Y axis. The direction in which the Y axis extends is the direction in which the fork 48 and the pallet 20 face each other. The relative angle can be said to be the relative angle between the fork 48 and the insertion hole 31 with respect to the direction in which the fork 48 and the pallet 20 face each other.

[0033] The point cloud map M1 may include at least a point P1 that represents the position of the demarcated surface in the coordinates of the sensor coordinate system. The point cloud map M1 may also include a point P1 that represents the position of the through hole demarcated surface 32, 34 in the coordinates of the sensor coordinate system.

[0034] The alignment control performed by the control device 65 will be described. The alignment control is a control for raising and lowering the fork 48 and tilting the fork 48 so that the fork 48 is smoothly inserted into the insertion hole 31. In the alignment control, the fork 48 may be moved left and right. For example, the forklift 40 approaches the truck 10 based on a command from a higher-level control device. Then, when the distance between the forklift 40 and the truck 10 becomes less than a predetermined distance, the alignment control is started. The predetermined distance is, for example, a distance at which the pallet 20 can be detected by the external sensor 61. While the alignment control is being performed, the forklift 40 moves forward toward the pallet 20.

[0035] 9, in step S1, the control device 65 acquires point cloud data from the external sensor 61. A laser emitted from the external sensor 61 is irradiated onto the inside of the insertion hole 31. The point cloud data is data including points obtained by irradiating a demarcated surface with a laser.

[0036] Next, in step S2, the control device 65 derives the relative distance and the relative angle. The control device 65 performs scan matching between the point cloud data acquired in step S1 and the point cloud map M1. The scan matching can be performed using, for example, NDT (Normal Distributions Transform) or ICP (Iterative Closest Point).

[0037] The control device 65 performs scan matching between the point cloud data and the point cloud map M1 so that the distance between the point of the point cloud data and the point P1 of the point cloud map M1 corresponding to the point of the point cloud data is shortened. The point P1 of the point cloud map M1 corresponding to the point of the point cloud data is the point P1 assumed to represent the same position as the coordinates corresponding to the point of the point cloud data. In other words, the point P1 of the point cloud map M1 corresponding to the point of the point cloud data is the point P1 assumed to represent the same object as the point of the point cloud data. By performing scan matching, the control device 65 can specify how to move and rotate the point cloud data to match the point cloud map M1.

[0038] The control device 65 can derive the distance difference of the point cloud data with respect to the point cloud map M1. The distance difference of the point cloud data with respect to the point cloud map M1 is the difference between the position of the demarcated surface represented by the point cloud map M1 and the position of the demarcated surface represented by the point cloud data. The point cloud map M1 is acquired in a state where the relative distance is 0. Therefore, when there is no distance difference between the point cloud map M1 and the point cloud data, it can be said that the relative distance is in a state of 0. When there is a deviation in the positions of the fork 48 and the insertion hole 31 on the XZ plane, the point cloud data is deviated from the point cloud map M1 by the amount of this deviation. It can be said that the distance difference between the point cloud map M1 and the point cloud data represents the amount of deviation in the positions of the fork 48 and the insertion hole 31 on the XZ plane.

[0039] The control device 65 can derive the inclination of the point cloud data relative to the point cloud map M1. The inclination of the point cloud data relative to the point cloud map M1 is the difference in attitude between the demarcation surface represented by the point cloud map M1 and the demarcation surface represented by the point cloud data. In this embodiment, the attitude is the inclination relative to the Y axis of the sensor coordinate system. If the point cloud data is not inclined relative to the point cloud map M1, the relative angle can be said to be 0. If there is a deviation between the attitude of the fork 48 and the attitude of the demarcation surface, the point cloud data is inclined relative to the point cloud map M1 by the amount of this deviation. The inclination of the point cloud data relative to the point cloud map M1 can be said to represent a relative angle.

[0040] Next, in step S3, the control device 65 aligns the forks 48. Aligning the forks 48 means adjusting the positions of the forks 48 so that the insertion portions 49 do not come into contact with the demarcation surface. The control device 65 adjusts the positions of the forks 48 so that the relative distance falls within a specified range. The specified range is a range that is set so that the forks 48 do not come into contact with the pallet 20 while the forks 48 are being inserted into the insertion holes 31.

[0041] When the relative distance in the direction in which the Z axis extends is not within a specified range, the control device 65 controls the hydraulic mechanism 64 to raise and lower the fork 48. The control device 65 raises and lowers the fork 48 so as to shorten the relative distance. When the relative distance in the direction in which the Z axis extends falls within a specified range, the control device 65 stops the fork 48.

[0042] The control device 65 moves the fork 48 in the left-right direction when the relative distance in the direction in which the X-axis extends is not within a specified range. The control device 65 may control the drive mechanism 63 to perform steering to move the fork 48 in the left-right direction. When the forklift 40 is equipped with a side shift device, the control device 65 may move the fork 48 in the left-right direction by the side shift device. The side shift device is equipped with a side shift cylinder, and moves the fork 48 in the left-right direction by supplying and discharging hydraulic oil to the side shift cylinder. The control device 65 moves the fork 48 in the left-right direction so that the relative distance becomes shorter. The control device 65 stops the fork 48 when the relative distance in the direction in which the X-axis extends falls within a specified range.

[0043] The control device 65 adjusts the position of the fork 48 so that the relative angle falls within a specified angle range. The specified angle range is a range set so that the fork 48 and the pallet 20 do not come into contact with each other while the fork 48 is being inserted into the insertion hole 31. If the relative angle does not fall within the specified angle range, the control device 65 controls the hydraulic mechanism 64 to tilt the fork 48. The control device 65 tilts the fork 48 so that the relative angle becomes smaller. When the relative angle falls within the specified angle range, the control device 65 stops the fork 48. It can be said that the positioning of the fork 48 is performed so that the point cloud data overlaps with the point cloud map M1.

[0044] Next, in step S4, the control device 65 determines whether or not the insertion of the forks 48 has been completed. Whether or not the insertion of the forks 48 has been completed can be determined from the detection result of the loading sensor 62. If the pallet 20 is loaded on the forks 48, the control device 65 determines that the insertion has been completed. If the pallet 20 is not loaded on the forks 48, the control device 65 determines that the insertion has not been completed. If the determination result of step S4 is negative, the control device 65 returns to step S1. If the determination result of step S4 is positive, the control device 65 ends the alignment control.

[0045] When the alignment control ends, the forward movement of the forklift 40 is stopped. The control device 65 derives the relative distance and the relative angle while the forklift 40 is moving forward. The control device 65 aligns the position of the fork 48 based on the relative distance and the relative angle while the forklift 40 is moving forward. While the forklift 40 is moving forward, the fork 48 is inserted into the insertion hole 31. The control device 65 derives the relative distance and the relative angle while the fork 48 is being inserted into the insertion hole 31. While the fork 48 is being inserted into the insertion hole 31, the control device 65 adjusts the position of the fork 48 so that the fork 48 does not come into contact with the pallet 20.

[0046] The operation of the first embodiment will be described. The fork 48 may come into contact with the demarcated surface during the process of inserting the fork 48 into the insertion hole 31. By deriving the relative distance and the relative angle from the point cloud data, the relative distance and the relative angle according to the insertion amount of the fork 48 can be derived. If the relative distance and the relative angle increase during the insertion of the fork 48 into the insertion hole 31, the position of the fork 48 can be adjusted accordingly. If the relative distance and the relative angle are derived using the insertion opening, which is the opening of the insertion hole 31, the positional relationship between the pallet 20 and the fork 48 inside the pallet 20 cannot be grasped even if the relative distance and the relative angle are derived during the insertion of the fork 48. Therefore, there is a risk that the pallet 20 and the fork 48 may come into contact with each other. In contrast, if the relative distance and the relative angle are derived using the coordinates of the demarcated surface, the positional relationship between the pallet 20 and the fork 48 can be grasped in real time according to the insertion amount of the fork 48. The control device 65 can adjust the position of the fork 48 while the fork 48 is being inserted into the insertion hole 31 by adjusting the position of the fork 48 based on the relative distance and the relative angle.

[0047] The effects of the first embodiment will be described. (1-1) The control device 65 aligns the position of the fork 48 while the fork 48 is being inserted. Even while the fork 48 is being inserted, the position of the fork 48 can be adjusted so that the fork 48 does not come into contact with the pallet 20. This makes it possible to prevent the fork 48 from coming into contact with the pallet 20 until the insertion of the fork 48 is completed.

[0048] (1-2) The control device 65 derives the relative distance and the relative angle by scan matching between the point cloud map M1 and the point cloud data. By using the point cloud map M1 acquired in a state where the relative distance is 0 and the relative angle is 0, the distance difference between the point cloud map M1 and the point cloud data can be regarded as the relative distance. The inclination of the point cloud data with respect to the point cloud map M1 can be regarded as the relative angle. Therefore, the control device 65 can easily derive the relative distance and the relative angle by performing scan matching.

[0049] In addition, by performing scan matching between the point cloud map M1 and the point cloud data, it is easy to derive the relative distance and the relative angle even when the demarcation surface has a complex shape, such as when the demarcation surface has undulations. When the pallet 20 has the through-hole demarcation surfaces 32, 34 as in the embodiment, the demarcation surface has undulations. In such a case, it may be difficult to detect a plane from the point cloud data, and it may be difficult to derive the relative distance and the relative angle by detecting the plane. In contrast, by scan matching between the point cloud map M1 and the point cloud data, it is possible to derive the relative distance and the relative angle without detecting the plane. Therefore, it is possible to derive the relative distance and the relative angle without depending on the shape of the demarcation surface.

[0050] Second embodiment A second embodiment of the forklift will be described. In the second embodiment, the positioning control performed by the control device is different from that in the first embodiment. The positioning control in the second embodiment will be described.

[0051] 10, in step S11, the control device 65 acquires point cloud data. The process of step S11 is similar to the process of step S1. Next, in step S12, the control device 65 detects a plane from the point cloud map M1. More specifically, the control device 65 detects at least one of the first inner surface 23, the second inner surface 26, the first surface 28, and the second surface 30 from the point cloud map M1. The control device 65 calculates a normal vector of each point P1 of the point cloud map M1. The normal vector is a vector that is oriented in a direction perpendicular to the plane surrounded by the multiple points P1. Methods for deriving the normal vector include a method of determining a curved surface from each point P1 and deriving the normal vector of each point P1 from the curved surface, and a method using the cross product of vectors. For example, when the control device 65 determines the normal vector of one point P1, it determines the cross product of vectors that are directed from this point P1 to each of two points P1 located within a predetermined range. This cross product is the normal vector.

[0052] When detecting at least one of the first inner surface 23 and the second inner surface 26 from the point cloud map M1, the control device 65 extracts a point P1 whose normal vector is oriented in the up-down direction. More specifically, the control device 65 determines whether the angle of the normal vector with respect to the XY plane of the sensor coordinate system is within a predetermined range. The XY plane is a plane defined by the X-axis and the Y-axis of the sensor coordinate system. If the point P1 is the point P1 representing the first inner surface 23 or the second inner surface 26, the angle of the normal vector of the point P1 with respect to the XY plane is 90°. In this embodiment, a predetermined range is set based on the inclination of the loading platform 11 due to the stopping position of the truck 10, the accuracy of the external sensor 61, and the like. The range is, for example, 90°±a predetermined angle. The predetermined angle is, for example, 10°. The control device 65 extracts a point P1 whose angle of the normal vector with respect to the XY plane falls within a predetermined range as a point P1 whose normal vector is oriented in the up-down direction. This point P1 represents the first inner surface 23 or the second inner surface 26.

[0053] When detecting at least one of the first surface 28 and the second surface 30 from the point cloud map M1, the control device 65 may extract a point P1 whose normal vector angle with respect to the YZ plane of the sensor coordinate system is within a predetermined range. The point P1 extracted in this way is a point representing the first surface 28 or the second surface 30. The YZ plane is a plane defined by the Y axis and the Z axis of the sensor coordinate system.

[0054] Next, in step S13, the control device 65 detects a plane from the point cloud data. The control device 65 detects the same plane as the plane detected in step S12 from the point cloud data. If the first inner surface 23 is detected in step S12, the first inner surface 23 is detected from the point cloud data in step S13. If the first inner surface 23 and the first surface 28 are detected in step S12, the first inner surface 23 and the first surface 28 are detected from the point cloud data in step S13. The detection of the plane in step S13 can be achieved by performing on the point cloud data the processing performed on the point cloud map M1 in step S12.

[0055] Next, in step S14, the control device 65 derives a relative distance and a relative angle. The control device 65 determines the distance difference between the plane represented by the point P1 extracted in step S12 and the plane represented by the point extracted in step S13 as the relative distance. When calculating the distance difference, the distance difference between the same planes is calculated. For example, when the first inner surface 23 and the first surface 28 are detected in step S12 and step S13, respectively, the control device 65 calculates the distance difference between the first inner surfaces 23, and calculates the distance difference between the first surfaces 28. When calculating the distance difference using a plurality of planes, the control device 65 may calculate an average value of the distance differences.

[0056] The control device 65 determines the inclination of the plane detected from the point cloud data relative to the plane detected from the point cloud map M1 as a relative angle. When calculating the inclination, the control device 65 calculates the inclination between the same planes. When calculating the inclination using multiple planes, the control device 65 may calculate the average value of the inclination.

[0057] Next, in step S15, the control device 65 aligns the forks 48. The process of step S15 is similar to the process of step S3. Next, in step S16, the control device 65 judges whether or not the insertion of the fork 48 is completed. The process of step S16 is the same as that of step S4. If the judgment result of step S16 is negative, the control device 65 returns to step S11. If the judgment result of step S16 is positive, the control device 65 ends the alignment control.

[0058] The effects of the second embodiment will be described below. In addition to the effect (1-1) of the first embodiment, the second embodiment can provide the following effects. (2-1) The control device 65 derives the relative distance and the relative angle based on the plane detected from the point cloud map M1 and the plane detected from the point cloud data. This reduces the calculation cost of the control device 65 compared to deriving the relative distance and the relative angle by scan matching between the point cloud map M1 and the point cloud data.

[0059] Each embodiment can be modified as follows: Each embodiment and the following modified examples can be combined with each other to the extent that there is no technical contradiction. In the first embodiment, the positioning control performed by the control device 65 may be modified as follows. When performing the positioning control as described below, the external sensor 61 is disposed so that the fork 48 is always located within the detection range of the external sensor 61.

[0060] 11, in step S21, the control device 65 acquires point cloud data. The process of step S21 is similar to that of step S1. Next, in step S22, the control device 65 detects the position and attitude of the fork 48. The position of the fork 48 is the coordinates of the fork 48 in the sensor coordinate system. The attitude of the fork 48 is the inclination of the fork 48 with respect to the Y axis of the sensor coordinate system. The control device 65, for example, extracts a point representing the upper surface 50 of the fork 48 from the point cloud data. When the relative position between the external sensor 61 and the fork 48 is constant, a point at a predetermined position may be extracted from the point cloud data. When the relative position between the external sensor 61 and the fork 48 changes, a point representing the upper surface 50 of the fork 48 may be extracted using a trained model that has been machine-learned using an algorithm such as DNN (Deep Neural Network). The control device 65 derives the position of the fork 48 from the upper surface 50 of the fork 48. The control device 65 derives the attitude of the fork 48 from the inclination of the upper surface 50 of the fork 48 with respect to the Y axis.

[0061] Next, in step S23, the control device 65 detects the position and attitude of the insertion hole 31. The position of the insertion hole 31 is the coordinates of the insertion hole 31 in the sensor coordinate system. The attitude of the insertion hole 31 is the inclination of the insertion hole 31 with respect to the Y axis of the sensor coordinate system. The control device 65, for example, extracts points representing the demarcated surface from the point cloud data. The extraction of the points representing the demarcated surface can be performed by detecting a plane, as in step S13. The control device 65 derives the position of the insertion hole 31 from the demarcated surface. The control device 65 derives the attitude of the insertion hole 31 from the inclination of the demarcated surface with respect to the Y axis.

[0062] Next, in step S24, the control device 65 derives the relative distance and the relative angle. The control device 65 determines the difference between the position of the fork 48 and the position of the insertion hole 31 as the relative distance. The control device 65 determines the difference between the posture of the fork 48 and the posture of the insertion hole 31 as the relative angle.

[0063] Next, in step S25, the control device 65 aligns the forks 48. The process of step S25 is similar to the process of step S3. Next, in step S26, the control device 65 judges whether or not the insertion of the fork 48 is completed. The process of step S26 is the same as that of step S4. If the judgment result of step S26 is negative, the control device 65 returns to step S21. If the judgment result of step S26 is positive, the control device 65 ends the alignment control.

[0064] When performing the position matching control as described above, it is possible to derive the relative distance and the relative angle without using the point cloud map M1, and therefore the auxiliary storage device 68 does not need to store the point cloud map M1.

[0065] In the first embodiment, the control device 65 may stop the loading operation when the correspondence between the point cloud map M1 and the point cloud data is low. The more the number of matches between the point P1 of the point cloud map M1 and the point cloud data, the higher the correspondence between the point cloud map M1 and the point cloud data. The control device 65 may stop the loading operation depending on the number of matches between the point P1 of the point cloud map M1 and the point cloud data. When the correspondence between the point cloud map M1 and the point cloud data is low, it is expected that the forklift 40 is approaching a pallet other than the pallet 20 to be loaded on the fork 48, or that the pallet 20 is broken. In such a case, by stopping the loading operation, it is possible to prevent the forklift 40 from attempting to load the cargo even though the cargo cannot be loaded.

[0066] In each embodiment, the control device 65 may only align the fork 48 with respect to the direction in which the Z axis extends. In this case, the control device 65 may derive only the relative distance with respect to the direction in which the Z axis extends as the relative distance.

[0067] In each embodiment, the control device 65 may only align the fork 48 with respect to the extension direction of the X-axis. In this case, the control device 65 may derive only the relative distance with respect to the extension direction of the X-axis as the relative distance.

[0068] In each embodiment, the point cloud map M1 may be stored in the storage unit 67. In this case, the storage unit 67 is a storage device. In each embodiment, the point cloud map M1 may be a set of points that represent the positions of the demarcation plane in the coordinates of the sensor coordinate system when the forks 48 are not in contact with the pallet 20. The point cloud map M1 may be coordinates acquired when the relative distance is greater than 0 and the relative angle is greater than 0.

[0069] In each embodiment, the forklift 40 can load the pallet 20 placed in any position onto the forks 48. Examples of the arbitrary position include a shelf and the ground.

[0070] In each embodiment, the forklift 40 may be a forklift that is operated by an operator. In this case, when the forklift 40 is approached by the operator, the control device 65 may align the forks 48. [Explanation of symbols]

[0071] M1...point cloud map, P1...point, 20...pallet, 23...first inner surface as demarcating surface, 26...second inner surface as demarcating surface, 28...first surface as demarcating surface, 30...second surface as demarcating surface, 31...insertion hole, 40...forklift, 48...fork, 61...external sensor, 65...control device, 68...auxiliary memory device as memory device.

Claims

1. Fork and An external sensor that detects the position of an object in a three-dimensional coordinate system; A control device, The control device acquires point cloud data, which is a set of points representing the positions of a demarcation surface that defines an insertion hole of a pallet and includes a surface extending in a horizontal direction and a surface extending in a vertical direction, from the external sensor; Deriving from the point cloud data a relative distance between the fork and the insertion hole in a direction perpendicular to the direction in which the fork and the pallet face each other, and a relative angle between the fork and the insertion hole with respect to the direction in which the fork and the pallet face each other; A forklift that adjusts positions of the forks based on the relative distance and the relative angle so that the forks do not come into contact with the pallet while inserting the forks into the insertion holes.

2. The forklift is A storage device is provided, the storage device stores a point cloud map that is a set of points that represent the position of the demarcation plane in a state where the fork and the pallet are not in contact with each other, using coordinates in the three-dimensional coordinate system; The forklift according to claim 1 , wherein the control device derives the relative distance from a distance difference of the point cloud data with respect to the point cloud map, and derives the relative angle from an inclination of the point cloud data with respect to the point cloud map.

3. The forklift is A storage device is provided, the storage device stores a point cloud map that is a set of points that represent the position of the demarcation plane in a state where the fork and the pallet are not in contact with each other, using coordinates in the three-dimensional coordinate system; The control device includes: Detecting a plane from the point cloud map; Detecting a plane identical to the plane from the point cloud data; 2. The forklift according to claim 1, wherein the relative distance is derived from a distance difference between the plane detected from the point cloud map and the plane detected from the point cloud data, and the relative angle is derived from an inclination of the plane detected from the point cloud data with respect to the plane detected from the point cloud map.

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