Forklift Side Shift Control Device

Abstract

To provide a side shift control device for a forklift capable of placing a pallet on a side position of an object so that there is no gap between the pallet and the object while preventing the pallet from excessively pushing-in the object.SOLUTION: A side shift control device 30 comprises: a side shift control unit 33 which controls a side shift unit 28 so that a fork 8 starts to move to the side of an existing pallet 3A after the fork 8 is inserted into a pair of fork holes 11 provided in the pallet 3; laser sensors 23A-23D which detects an operational state of the pallet 3 in the state in which the fork 8 is inserted into the fork holes 11; and an abutting determination unit 34 which determines whether or not the pallet 3 abuts against the existing pallet 3A based on the operational state of the pallet 3 detected by the laser sensors 23A-23D.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a side shift control device for a forklift.

Background Art

[0002] For example, Patent Document 1 describes a forklift equipped with a side shift device. The side shift device described in Patent Document 1 includes a lift bracket that moves up and down along a mast, a backrest provided on the lift bracket to which a fork is attached, and a shift mechanism that shifts the fork in the width direction (left and right direction) of the vehicle body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, for example, when loading a load on the loading platform of a truck, the side shift device is used to bring adjacent pallets into contact with each other so that the pallets are placed on the loading platform without gaps between adjacent pallets. At this time, when automatically performing the side shift of the fork, if the side shift amount (movement amount) of the fork is excessively instructed, objects such as the adjacent pallet or the side wall of the loading platform will be excessively pushed in. For this reason, there is a risk that the pallet will be damaged, or the truck will shake and the goods loaded on the truck will collapse.

[0005] An object of the present invention is to provide a side shift control device for a forklift that can place a pallet at a lateral position of an object so that there is no gap between the pallet and the object while preventing the pallet from excessively pushing in the object.

Means for Solving the Problems

[0006] One aspect of the present invention is a side shift control device for a forklift that moves a pair of forks in the left - right direction by a side shift unit to bring a pallet held by the pair of forks into contact with an object when placing the pallet at a lateral position of the object. The side shift control device includes a side shift control unit that controls the side shift unit to start the movement of the forks toward the object side after the forks are inserted into a pair of fork holes provided in the pallet, a detection unit that detects the operating state of the pallet in a state where the forks are inserted into the fork holes, and a determination unit that determines whether the pallet has come into contact with the object based on the operating state of the pallet detected by the detection unit.

[0007] In such a side shift control device, after the forks are inserted into a pair of fork holes provided in the pallet, the side shift unit starts the movement of the forks toward the object side. Then, the operating state of the pallet in a state where the forks are inserted into the fork holes of the pallet is detected, and based on the operating state of the pallet, it is determined whether the pallet has come into contact with the object. Therefore, even if the pallet held by the forks comes into contact with the object, by immediately stopping the movement of the forks toward the object side by the side shift unit, the object is prevented from being excessively pressed against the pallet. As a result, while preventing the pallet from excessively pushing into the object, the pallet is placed at the lateral position of the object so that there is no gap between the pallet and the object.

[0008] The detection unit is a laser sensor that is fixed to at least the outer side surface in the left - right direction or at least the inner side surface in the left - right direction of the proximal end side portion of the pair of forks, and irradiates a linear laser toward the pallet to detect whether the laser is reflected by the front end surface of the pallet. The determination unit determines whether the pallet is in a state of sliding relatively on the forks based on the detection data of the laser sensor, and when the pallet is in a state of sliding relatively on the forks, it may be determined that the pallet has come into contact with the object.

[0009] In such a configuration, when the fork moves toward the object side by the side shift unit and the pallet held by the fork abuts against the object, the pallet slides relative to the fork. Then, when it is detected that the linear laser emitted from the laser sensor is reflected by the front end face of the pallet, it is determined that the pallet is in a state of sliding relative to the fork, and it is determined that the pallet has abutted against the object. Therefore, it is possible to accurately determine whether the pallet has abutted against the object by using an inexpensive laser sensor.

[0010] The detection unit is at least one of an image sensor that images the fork hole and a distance measurement sensor that measures the distance to the pallet, and the determination unit determines whether the relative position of the pallet with respect to the fork has started to shift based on at least one of the image data of the image sensor and the measurement data of the distance measurement sensor. When the relative position of the pallet with respect to the fork has started to shift, it may be determined that the pallet has abutted against the object.

[0011] In such a configuration, when the fork moves toward the object side by the side shift unit and the pallet held by the fork abuts against the object, the relative position of the pallet with respect to the fork shifts. Then, when it is determined that the relative position of the pallet with respect to the fork has started to shift by using at least one of the image sensor and the distance measurement sensor, it is determined that the pallet has abutted against the object. When at least one of the image sensor and the distance measurement sensor is already installed in the forklift, the number of parts can be reduced, and the costs associated with installation and maintenance can be suppressed.

[0012] The side shift control device further includes a determination unit that determines whether the fork is in contact with or close to the inner wall surface of the pallet that defines the fork hole based on the operation state of the pallet detected by the detection unit, and an initial side shift control unit that controls the side shift unit to move the fork toward the center in the left-right direction of the fork hole when the determination unit determines that the fork is in contact with or close to the inner wall surface of the pallet. After the control process by the initial side shift control unit is executed, the side shift control unit may control the side shift unit to start moving the pallet toward the object side.

[0013] In such a configuration, when the fork is inserted into the fork hole of the pallet and the fork is in contact with or close to the inner side surface of the pallet, the fork once moves toward the center in the left-right direction of the fork hole. Then, by starting to move the fork toward the object side, the pallet surely abuts against the object.

[0014] When the determination unit determines that the pallet has abutted against the object, the side shift control unit may control the side shift unit to stop moving the fork toward the object side.

[0015] In such a configuration, when it is determined that the pallet has abutted against the object, the movement of the fork toward the object side automatically stops, so that it is further prevented that the pallet excessively pushes into the object.

Advantages of the Invention

[0016] According to the present invention, while preventing the pallet from excessively pushing into the object, the pallet can be placed at a side position of the object so that there is no gap between the pallet and the object.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0019] FIG. 1 is a schematic plan view showing a forklift equipped with a side shift control device according to an embodiment of the present invention together with a pallet. In FIG. 1, the forklift 1 includes a vehicle body 2 and a cargo handling device 4 disposed on the front side of the vehicle body 2 for handling the pallet 3. The front-rear direction of the forklift 1 is defined as the X direction, and the left-right direction (vehicle width direction) of the forklift 1 is defined as the Y direction.

[0020] The cargo handling device 4 includes a mast 5 attached to the front end of the vehicle body 2, a pair of forks 8 that are attached to the mast 5 via a lift bracket 6 and a load bracket 7 so as to be movable up and down and hold the pallet 3, a lift cylinder 9 (see FIG. 2) for lifting and lowering each fork 8, and a side shift cylinder 10 (see FIG. 2) for moving each fork 8 in the left - right direction (Y - direction) by moving the load bracket 7 relative to the lift bracket 6 in the left - right direction. Note that although not particularly shown, the cargo handling device 4 also has a tilt cylinder for tilting the mast 5.

[0021] The pallet 3 is, for example, a flat pallet made of plastic or wood. The pallet 3 has a square shape in plan view. On the pallet 3, a load (not shown) is placed. The pallet 3 has a front end face 3a, a rear end face 3b, and two side faces 3c. The front end face 3a is the face that faces the forklift 1 when the pallet 3 is held by the forks 8.

[0022] The pallet 3 is provided with a pair of fork holes 11 into which each fork 8 is inserted. The fork holes 11 extend from the front end face 3a to the rear end face 3b of the pallet 3. The pallet 3 is provided with inner side faces 3d that define the fork holes 11. The inner side faces 3d are inner wall faces located on both the left and right sides of the fork holes 11.

[0023] When loading the pallet 3, for example, onto a truck (not shown), the pallet 3 is placed on the loading platform of the truck. At this time, adjacent pallets 3 in the left - right direction are arranged in a state where the side faces 3c are in contact with each other so that there is no gap between them (see FIG. 4).

[0024] FIG. 2 is a schematic configuration diagram showing a stacking control device equipped with a side shift control device according to the first embodiment of the present invention. In FIG. 2, the stacking control device 20 includes an image sensor 21, a distance measuring sensor 22, four laser sensors 23A to 23D, a traveling drive unit 24, a lift drive unit 25, a side shift drive unit 26, and a controller 27.

[0025] The stacking control device 20 is a device that automatically stacks loads at the stacking positions on the loading platform of the truck. The stacking positions are the side positions of the pallet 3 (the existing pallet 3A described later) already placed on the loading platform or the side positions of the wall portion of the loading platform. Note that the pallet 3 already placed on the loading platform and the wall portion of the loading platform correspond to objects.

[0026] The image sensor 21 is a camera that images the front of the forklift 1 to acquire image data. The image sensor 21 is attached to the mast 5, for example.

[0027] The distance measuring sensor 22 measures the distance to an object located in front of the forklift 1. As the distance measuring sensor 22, for example, a LIDAR (light detection and ranging) that irradiates a two-dimensional or three-dimensional laser and receives the reflected light from the object to measure the distance to the object is used. The distance measuring sensor 22 is attached to the mast 5, for example.

[0028] As shown in FIG. 1, the laser sensors 23A to 23D are fixed to the base end side portions of a pair of forks 8. Specifically, the laser sensor 23A is fixed to the left side surface 8a (the outer side surface in the left-right direction) of the base end side portion of the fork 8 located on the left side when facing the front of the forklift 1. The laser sensor 23B is fixed to the right side surface 8a (the inner side surface in the left-right direction) of the base end side portion of the fork 8 located on the left side when facing the front of the forklift 1. The laser sensor 23C is fixed to the left side surface 8a (the inner side surface in the left-right direction) of the base end side portion of the fork 8 located on the right side when facing the front of the forklift 1. The laser sensor 23D is fixed to the right side surface 8a (the outer side surface in the left-right direction) of the base end side portion of the fork 8 located on the right side when facing the front of the forklift 1.

[0029] The laser sensors 23A to 23D irradiate a linear (one-dimensional) laser toward the pallet 3 in a state where the fork 8 is inserted into the fork hole 11 of the pallet 3, and detect whether the laser is reflected by the front end face 3a of the pallet 3. The laser sensors 23A to 23D irradiate the laser in the extending direction of the fork 8 (see FIG. 4).

[0030] By detecting the laser reflected by hitting the front end face 3a of the pallet 3, the laser sensors 23A to 23D can know the operating state of the pallet 3 in a state where the fork 8 is inserted into the fork hole 11 of the pallet 3. Therefore, the laser sensors 23A to 23D constitute a detection unit that detects the operating state of the pallet 3 in a state where the fork 8 is inserted into the fork hole 11 of the pallet 3.

[0031] The traveling drive unit 24 is a drive unit for driving the forklift 1 to travel. The traveling drive unit 24 has, for example (not shown in the figure), a traveling motor for driving the forklift 1 to travel and a steering motor for steering the forklift 1.

[0032] The lifting drive unit 25 is a drive unit for expanding and contracting the lift cylinder 9. The lifting drive unit 25 is, for example (not shown in the figure), an electromagnetic control valve arranged between the hydraulic pump and the lift cylinder 9.

[0033] The side shift drive unit 26 is a drive unit for expanding and contracting the side shift cylinder 10. The side shift drive unit 26 is, for example (not shown in the figure), an electromagnetic control valve arranged between the hydraulic pump and the side shift cylinder 10. The side shift drive unit 26 cooperates with the side shift cylinder 10 to constitute the side shift unit 28.

[0034] The controller 27 is composed of a CPU, a RAM, a ROM, an input / output interface, etc. The controller 27 has a cargo handling control unit 31, a traveling control unit 32, a side shift control unit 33, and a contact determination unit 34 (determination unit).

[0035] When the fork 8 is inserted into the fork hole 11 of the pallet 3, the load handling control unit 31 controls the lift drive unit 25 to raise the fork 8 so that the fork 8 holds the pallet 3.

[0036] The travel control unit 32 controls the travel drive unit 24 so that the forklift 1 with the pallet 3 held by the fork 8 travels to the loading position.

[0037] When the forklift 1 reaches the loading position, the side shift control unit 33 controls the side shift drive unit 26 to start the movement (side shift) of the fork 8 toward the pallet 3 already placed on the loading platform. Here, the pallet 3 already placed on the loading platform is regarded as the existing pallet 3A (see FIG. 4).

[0038] After the fork 8 is inserted into the pair of fork holes 11 provided in the pallet 3, the side shift control unit 33 controls the side shift unit 28 to start the movement of the fork 8 toward the existing pallet 3A.

[0039] Based on the operating state of the pallet 3 detected by the laser sensors 23A to 23D, the contact determination unit 34 determines whether the pallet 3 held by the fork 8 has come into contact with the existing pallet 3A.

[0040] Based on the detection data of the laser sensors 23A to 23D, the contact determination unit 34 determines whether the pallet 3 held by the fork 8 is in a state of sliding relative to the fork 8. When the pallet 3 is in a state of sliding relative to the fork 8, the contact determination unit 34 determines that the pallet 3 held by the fork 8 has come into contact with the existing pallet 3A.

[0041] Here, the laser sensors 23A to 23D, the side shift control unit 33 and the contact determination unit 34 of the controller 27 constitute the side shift control device 30 of the present embodiment. The side shift control device 30 is a device that moves a pair of forks 8 in the left - right direction by a side shift unit 28 to bring the pallet 3 held by the pair of forks 8 into contact with an existing pallet 3A when placing the pallet 3 held by the pair of forks 8 at a lateral position of the existing pallet 3A.

[0042] FIG. 3 is a flowchart showing the details of the control processing procedure executed by the controller 27. This processing is executed when the fork 8 is inserted into the fork hole 11 of the pallet 3. Whether the fork 8 has been inserted into the fork hole 11 is determined from, for example, the image data of the image sensor 21 or the measurement data of the distance measurement sensor 22.

[0043] In FIG. 3, the controller 27 first controls the lift drive unit 25 so as to raise the fork 8 so that the fork 8 holds the pallet 3 (step S101). Subsequently, the controller 27 controls the travel drive unit 24 so as to drive the forklift 1 to the loading position (step S102).

[0044] Subsequently, the controller 27 controls the side shift drive unit 26 to start the movement of the fork 8 toward the existing pallet 3A side (step S103). Then, as shown in FIG. 4(a), the pallet 3 held by the fork 8 moves toward the existing pallet 3A side.

[0045] Subsequently, the controller 27 acquires the detection data of the laser sensors 23A to 23D (step S104). Then, based on the detection data of the laser sensors 23A to 23D, the controller 27 determines whether the pallet 3 held by the fork 8 has slid completely over the fork 8 (step S105).

[0046] As shown in FIG. 4(b), when the pallet 3 held by the fork 8 abuts against the existing pallet 3A, the pallet 3 stops moving toward the existing pallet 3A side. On the other hand, since the fork 8 continues to move toward the existing pallet 3A side by the side shift unit 28, the pallet 3 slides horizontally on the fork 8 relatively.

[0047] However, as shown in FIG. 4(b), even when the pallet 3 held by the fork 8 abuts against the existing pallet 3A and the pallet 3 slides horizontally on the fork 8 relatively, if all the lasers L emitted from the laser sensors 23A to 23D are not reflected by the front end face 3a of the pallet 3 and the reflected light from the front end face 3a of the pallet 3 is not received by the laser sensors 23A to 23D, it is determined that the pallet 3 has not slid completely on the fork 8.

[0048] On the other hand, as shown in FIG. 4(c), when the laser L emitted from one of the laser sensors 23B and 23D and the laser sensors 23A and 23C is not reflected by the front end face 3a of the pallet 3, but the laser L emitted from the other of the laser sensors 23B and 23D and the laser sensors 23A and 23C is reflected by the front end face 3a of the pallet 3 and the reflected light from the front end face 3a of the pallet 3 is received by the other of the laser sensors 23B and 23D and the laser sensors 23A and 23C, it is determined that the pallet 3 has slid completely on the fork 8 relatively.

[0049] In this embodiment, the laser L emitted from the laser sensors 23B and 23D is not reflected by the front end face 3a of the pallet 3, but the laser L emitted from the laser sensors 23A and 23C is reflected by the front end face 3a of the pallet 3 and the reflected light from the front end face 3a of the pallet 3 is received by the laser sensors 23A and 23C.

[0050] Subsequently, when the controller 27 determines that the pallet 3 held by the fork 8 has not slid all the way relative to the fork 8, the above-described procedure S104 is executed again. When the controller 27 determines that the pallet 3 held by the fork 8 has slid all the way relative to the fork 8, the side shift drive unit 26 is controlled to stop the movement of the fork 8 toward the existing pallet 3A side (procedure S106).

[0051] Subsequently, the controller 27 controls the lift drive unit 25 so that the pallet 3 is placed on the loading platform by lowering the fork 8 (procedure S107). Thus, the stacking operation for one pallet 3 is completed.

[0052] Here, the handling control unit 31 executes procedures S101 and S107. The travel control unit 32 executes procedure S102. The side shift control unit 33 executes procedures S103 and S106. The contact determination unit 34 executes procedures S104 and S105.

[0053] In the stacking control device 20 as described above, with the forklift 1 positioned on the front side of the pallet 3 at the loading position, the fork 8 is inserted into the fork hole 11 of the pallet 3 as the forklift 1 moves forward. In that state, the fork 8 is lifted by the lift cylinder 9 so that the fork 8 lifts and holds the pallet 3.

[0054] Then, the forklift 1 travels to the loading position on the loading platform of the truck. At this time, as shown in FIG. 4(a), an existing pallet 3A is placed on the loading platform of the truck. For this reason, the loading position is the position on the right side of the existing pallet 3A on the loading platform. Further, the forklift 1 is stopped at the loading position so that the pallet 3 held by the fork 8 is separated from the existing pallet 3A by a predetermined distance to the right.

[0055] Next, the side shift unit 28 moves the fork 8 to the left toward the existing pallet 3A. Then, as shown in FIG. 4(b), the pallet 3 held by the fork 8 abuts against the existing pallet 3A. When the pallet 3 abuts against the existing pallet 3A, the pallet 3 slides relatively rightward on the fork 8.

[0056] Here, as shown in FIG. 4(b), when the pallet 3 held by the fork 8 abuts against the existing pallet 3A but not all of the laser L emitted from the laser sensors 23A to 23D is reflected by the front end face 3a of the pallet 3, the pallet 3 is sliding relatively rightward on the fork 8.

[0057] Then, as shown in FIG. 4(c), when the laser L emitted from the laser sensors 23A and 23C is reflected by the front end face 3a of the pallet 3, the pallet 3 held by the fork 8 is in a state of having slid completely rightward on the fork 8.

[0058] Then, the movement of the fork 8 to the left by the side shift unit 28 stops. Then, by lowering the fork 8 with the lift cylinder 9, the pallet 3 held by the fork 8 is placed on the right side of the existing pallet 3A on the loading platform. At this time, the left side surface 3c of the pallet 3 and the right side surface 3c of the existing pallet 3A are in contact.

[0059] As described above, in the present embodiment, after the fork 8 is inserted into the pair of fork holes 11 provided in the pallet 3, the side shift unit 28 starts moving the fork 8 toward the existing pallet 3A side. Then, the operating state of the pallet 3 with the fork 8 inserted into the fork hole 11 of the pallet 3 is detected, and based on the operating state of the pallet 3, it is determined whether the pallet 3 has come into contact with the existing pallet 3A. Therefore, even if the pallet 3 held by the fork 8 comes into contact with the existing pallet 3A, by immediately stopping the movement of the fork 8 toward the existing pallet 3A side by the side shift unit 28, it is possible to prevent the existing pallet 3A from being excessively pressed against the pallet 3. As a result, while preventing the pallet 3 from excessively pushing the existing pallet 3A, the pallet 3 is placed at the side position of the existing pallet 3A so that there is no gap between the pallet 3 and the existing pallet 3A. As a result, it is possible to prevent the pallet 3 and the existing pallet 3A from being damaged, or the truck from shaking and the cargo loaded on the truck from collapsing.

[0060] Further, in the present embodiment, when the fork 8 moves toward the existing pallet 3A side by the side shift unit 28 and the pallet 3 held by the fork 8 comes into contact with the existing pallet 3A, the pallet 3 starts to slide relatively on the fork 8. Then, when it is detected that the linearly irradiated laser L from the laser sensors 23A to 23D is reflected by the front end face 3a of the pallet 3, it is determined that the pallet 3 is in a state of sliding relatively on the fork 8, and it is determined that the pallet 3 has come into contact with the existing pallet 3A. Therefore, it is possible to accurately determine whether the pallet 3 has come into contact with the existing pallet 3A by using the inexpensive laser sensors 23A to 23D.

[0061] Further, in the present embodiment, when it is determined that the pallet 3 has come into contact with the existing pallet 3A, the movement of the fork 8 toward the existing pallet 3A side automatically stops, so that it is further possible to prevent the pallet 3 from excessively pushing the existing pallet 3A.

[0062] FIG. 5 is a schematic configuration diagram showing a stacking control device equipped with a side shift control device according to the second embodiment of the present invention. In FIG. 5, the stacking control device 20 includes a controller 27A instead of the controller 27 in the above-described first embodiment.

[0063] The controller 27A includes a position deviation determination unit 36 (determination unit), an initial side shift control unit 37, and the above-described cargo handling control unit 31, travel control unit 32, side shift control unit 33, and contact determination unit 34.

[0064] The position deviation determination unit 36 determines whether the fork 8 is in contact with or close to the inner surface 3d of the pallet 3 based on the detection data of the laser sensors 23A to 23D in a state where the fork 8 is inserted into the fork hole 11 of the pallet 3.

[0065] When the position deviation determination unit 36 determines that the fork 8 is in contact with or close to the inner surface 3d of the pallet 3, the initial side shift control unit 37 controls the side shift unit 28 to move the fork 8 toward the center G (see FIG. 7) in the left-right direction of the fork hole 11.

[0066] Here, the laser sensors 23A to 23D, the position deviation determination unit 36, the initial side shift control unit 37, the side shift control unit 33, and the contact determination unit 34 of the controller 27A constitute the side shift control device 30A of the present embodiment.

[0067] FIG. 6 is a flowchart showing the details of the control processing procedure executed by the controller 27A, corresponding to FIG. 3.

[0068] In FIG. 6, the controller 27A first acquires the detection data of the laser sensors 23A to 23D (step S111). Then, the controller 27A determines whether the fork 8 inserted into the fork hole 11 of the pallet 3 is in contact with or close to the inner surface 3d of the pallet 3 based on the detection data of the laser sensors 23A to 23D (step S112).

[0069] When the fork 8 is in contact with or close to the inner surface 3d of the pallet 3, as shown in FIG. 7(a), the laser L irradiated from one of the laser sensors 23A, 23C and the laser sensors 23B, 23D is reflected by the front end surface 3a of the pallet 3, and the reflected light from the front end surface 3a of the pallet 3 is received by one of the laser sensors 23A, 23C and the laser sensors 23B, 23D. Further, the state where the fork 8 is close to the inner surface 3d of the pallet 3 is a state where the distance between the side surface 8a of the fork 8 and the inner surface 3d of the pallet 3 is equal to or less than a specified value.

[0070] In this embodiment, when the fork 8 is in contact with or close to the inner surface 3d of the pallet 3, the laser L irradiated from the laser sensors 23A, 23C is reflected by the front end surface 3a of the pallet 3, and the reflected light from the front end surface 3a of the pallet 3 is received by the laser sensors 23A, 23C.

[0071] When the controller 27A determines that the fork 8 is in contact with or close to the inner surface 3d of the pallet 3, the controller 27A controls the side shift drive unit 26 to move the fork 8 toward the center G in the left - right direction of the fork hole 11 (procedure S113). At this time, as shown in FIG. 7(b), the controller 27A controls the side shift drive unit 26 to move the fork 8 to a position where the laser L irradiated from all the laser sensors 23A to 23D is not reflected by the front end surface 3a of the pallet 3.

[0072] Then, the controller 27A executes the above - mentioned procedures S101 to S107. When the controller 27A determines that the fork 8 is not in contact with the inner surface 3d of the pallet 3 and the fork 8 is not close to the inner surface 3d of the pallet 3, the controller 27A executes the procedures S101 to S107 without executing the above - mentioned procedure 113.

[0073] Here, the misalignment determination unit 36 executes procedures S111 and S112. The initial side shift control unit 37 executes procedure S113.

[0074] In such an embodiment, when the fork 8 is inserted into the fork hole 11 of the pallet 3 and the fork 8 is in contact with or close to the inner surface 3d of the pallet 3, the fork 8 first moves toward the center G in the left-right direction of the fork hole 11. Then, by starting the movement of the fork 8 toward the existing pallet 3A side, the pallet 3 reliably abuts against the existing pallet 3A.

[0075] FIG. 8 is a schematic configuration diagram showing a stacking control device provided with a side shift control device according to the third embodiment of the present invention. In FIG. 8, the stacking control device 20B does not include the laser sensors 23A to 23D in the above-described first embodiment. In this embodiment, the image sensor 21 and the distance measuring sensor 22 constitute a detection unit that detects the operating state of the pallet 3 when the fork 8 is inserted into the fork hole 11 of the pallet 3.

[0076] Further, the stacking control device 20B includes a controller 27B instead of the controller 27 in the above-described first embodiment. The controller 27B includes the above-described cargo handling control unit 31, traveling control unit 32, side shift control unit 33, and contact determination unit 34B.

[0077] The contact determination unit 34B determines whether the pallet 3 held by the fork 8 has abutted against the existing pallet 3A based on the operating state of the pallet 3 detected by the image sensor 21 and the distance measuring sensor 22.

[0078] The contact determination unit 34B determines whether the relative position of the pallet 3 with respect to the fork 8 has started to deviate based on the image data of the image sensor 21 and the measurement data of the distance measuring sensor 22, and when the relative position of the pallet 3 with respect to the fork 8 has started to deviate, determines that the pallet 3 held by the fork 8 has abutted against the existing pallet 3A.

[0079] Here, the image sensor 21, the distance measuring sensor 22, the side shift control unit 33 of the controller 27B, and the contact determination unit 34B constitute the side shift control device 30B of this embodiment.

[0080] FIG. 9 is a flowchart showing details of the control processing procedure executed by the controller 27B and corresponds to FIG. 3.

[0081] In FIG. 9, after executing the above-described procedures S101 to S103, the controller 27B acquires the image data of the image sensor 21 and the measurement data of the distance measurement sensor 22 (procedure S104B). Then, the controller 27B determines whether the relative position of the pallet 3 with respect to the fork 8 has started to shift based on the image data of the image sensor 21 and the measurement data of the distance measurement sensor 22 (procedure S105B).

[0082] At this time, regarding the image data of the image sensor 21, by comparing the latest image data with the previously acquired image data and detecting the positional shift of the pallet 3 or the load on the pallet 3, it is determined whether the relative position of the pallet 3 with respect to the fork 8 has started to shift.

[0083] Regarding the measurement data of the distance measurement sensor 22, when using LIDAR as the distance measurement sensor 22, since the position of the pallet 3 and the load on the pallet 3 is grasped by the distance measurement sensor 22, by detecting the change in the position of the pallet 3 and the load, it is determined whether the relative position of the pallet 3 with respect to the fork 8 has started to shift.

[0084] As described above, when the pallet 3 held by the fork 8 abuts on the existing pallet 3A, the pallet 3 stops moving toward the existing pallet 3A side, so that a behavior occurs in which the pallet 3 slides horizontally on the fork 8, and the relative position of the pallet 3 with respect to the fork 8 starts to shift. Therefore, when the relative position of the pallet 3 with respect to the fork 8 has not started to shift, it is determined that the pallet 3 held by the fork 8 is not in contact with the existing pallet 3A. When the relative position of the pallet 3 with respect to the fork 8 has started to shift, it is determined that the pallet 3 held by the fork 8 has come into contact with the existing pallet 3A.

[0085] When the controller 27B determines that the relative position of the pallet 3 with respect to the fork 8 has not started to shift, the controller 27B executes the above-described procedure S104B again. When the controller 27B determines that the relative position of the pallet 3 with respect to the fork 8 has started to shift, the controller 27B executes the above-described procedures S106 and S107.

[0086] Here, the contact determination unit 34B executes procedures S104B and S105B.

[0087] In such an embodiment of the present invention, as in the above-described first embodiment, even when the pallet 3 held by the fork 8 abuts against the existing pallet 3A, by immediately stopping the movement of the fork 8 toward the existing pallet 3A side, it is possible to suppress the excessive pressing of the existing pallet 3A against the pallet 3. As a result, while preventing the pallet 3 from excessively pushing in the existing pallet 3A, the pallet 3 is placed at a lateral position of the existing pallet 3A so that there is no gap between the pallet 3 and the existing pallet 3A.

[0088] Further, in the present embodiment, when the fork 8 moves toward the existing pallet 3A side by the side shift unit 28 and the pallet 3 held by the fork 8 abuts against the existing pallet 3A, the relative position of the pallet 3 with respect to the fork 8 starts to shift. Then, when it is determined using the image sensor 21 and the distance measuring sensor 22 that the relative position of the pallet 3 with respect to the fork 8 has started to shift, it is determined that the pallet 3 has abutted against the existing pallet 3A. When the image sensor 21 and the distance measuring sensor 22 are already provided in the forklift 1, the number of parts can be reduced, and the costs associated with mounting and maintenance can be suppressed.

[0089] Note that the present invention is not limited to the above-described embodiments. For example, in the above-described first and second embodiments, the laser sensors 23A and 23B are fixed to the left and right side surfaces 8a of the proximal end side portion of one fork 8, and the laser sensors 23C and 23D are fixed to the left and right side surfaces 8a of the proximal end side portion of the other fork 8, but it is not particularly limited to such a form.

[0090] For example, depending on the dimensions and positions of the fork holes 11 and the like, the laser L irradiated from the laser sensors 23A and 23C fixed to the left side surface 8a of the fork 8 may not be reflected by the front end surface 3a of the pallet 3, or the laser L irradiated from the laser sensors 23B and 23D fixed to the right side surface 8a of the fork 8 may not be reflected by the front end surface 3a of the pallet 3.

[0091] Therefore, as shown in Fig. 10(a), the laser sensor 23A may be fixed to the left side surface 8a in the proximal end portion of the left fork 8, and the laser sensor 23D may be fixed to the right side surface 8a in the proximal end portion of the right fork 8. That is, the laser sensors 23A and 23D may be fixed only to the outer side surfaces in the left-right direction in the proximal end portions of the pair of forks 8.

[0092] Also, as shown in Fig. 10(b), the laser sensor 23B may be fixed to the right side surface 8a in the proximal end portion of the left fork 8, and the laser sensor 23C may be fixed to the left side surface 8a in the proximal end portion of the right fork 8. That is, the laser sensors 23B and 23C may be fixed only to the inner side surfaces in the left-right direction in the proximal end portions of the pair of forks 8.

[0093] In the above first and second embodiments, based on the detection data of the laser sensors 23A to 23D, it is determined whether the pallet 3 held by the fork 8 is in a state of having slid completely relative to the fork 8, but it is not particularly limited to such a form. For example, depending on the mounting positions of the laser sensors 23A to 23D, even when the fork 8 inserted into the fork hole 11 of the pallet 3 and the inner side surface 3d of the pallet 3 are separated, the laser sensors 23A and 23C or the laser sensors 23B and 23D may receive the reflected light from the front end surface 3a of the pallet 3 (see Fig. 7(a)). Therefore, based on the detection data of the laser sensors 23A to 23D, it may be determined whether the pallet 3 held by the fork 8 is in a state of having slid relative to the fork 8.

[0094] Also, in the above-described third embodiment, it is determined whether the relative position of the pallet 3 with respect to the fork 8 has started to deviate based on the image data of the image sensor 21 and the measurement data of the distance measurement sensor 22. However, it is not particularly limited to such a form. For example, based only on the image data of the image sensor 21, it may be determined whether the relative position of the pallet 3 with respect to the fork 8 has started to deviate, or based only on the measurement data of the distance measurement sensor 22, it may be determined whether the relative position of the pallet 3 with respect to the fork 8 has started to deviate.

[0095] Also, instead of the above-described image sensor 21 and distance measurement sensor 22, a TOF camera (Time-of-Flight Camera) or the like may be used. Further, in the above-described third embodiment, the above-described second embodiment may be applied.

[0096] Also, in the above embodiment, when placing the pallet 3 held by the fork 8 at the lateral position of the existing pallet 3A, the fork 8 is moved in the left-right direction by the side shift unit 28 to bring the pallet 3 into contact with the existing pallet 3A. However, it is not particularly limited to such a form. For example, when placing the pallet 3 held by the fork 8 at the lateral position of the side wall, the fork 8 may be moved in the left-right direction by the side shift unit 28 to bring the pallet 3 into contact with the side wall. In this case, the side wall is an object with which the pallet 3 comes into contact.

[0097] Also, in the above embodiment, the pallet 3 is automatically placed at the lateral position of the object by automatic driving. However, the present invention is also applicable when the pallet 3 is placed at the lateral position of the object by the manual driving of the driver. In this case, when it is determined that the pallet 3 has come into contact with the object, an alarm may be given to the driver by an alarm or the like, or the movement of the fork 8 toward the object by the side shift unit 28 may be urgently stopped.

[0098] In addition, in the above embodiment, when loading the cargo, the side shift unit 28 is controlled so that the fork 8 holding the pallet 3 moves toward the object side. However, the present invention is not limited to cargo loading in particular, and is applicable as long as the side shift unit 28 moves the pair of forks 8 in the left-right direction so that the pallet 3 abuts against the object.

Explanation of Signs

[0099] 1... forklift, 3... pallet, 3A... existing pallet (object), 3a... front end face, 3d... inner face, 8... fork, 8a... side face, 11... fork hole, 21... image sensor (detection unit), 22... distance measurement sensor (detection unit), 23A to 23D... laser sensor (detection unit), 28... side shift unit, 30, 30A, 30B... side shift control device, 33... side shift control unit, 34, 34B... contact determination unit (determination unit), 36... displacement determination unit (determination unit), 37... initial side shift control unit, G... center, L... laser.

Claims

1. A side shift control device for a forklift that, when placing a pallet held by a pair of forks at a lateral position of an object, moves the pair of forks in the left - right direction by a side shift unit to bring the pallet into contact with the object, comprising: a side shift control unit that controls the side shift unit to start moving the forks toward the object side after the forks are inserted into a pair of fork holes provided in the pallet; a detection unit that detects the operating state of the pallet in a state where the forks are inserted into the fork holes; a determination unit that determines whether the pallet has come into contact with the object based on the operating state of the pallet detected by the detection unit, wherein the detection unit is a laser sensor fixed to at least the outer side surface in the left - right direction or at least the inner side surface in the left - right direction of the proximal end side portion of the pair of forks, and irradiates a linear laser toward the pallet to detect whether the laser is reflected by the front end surface of the pallet; and the determination unit determines, based on the detection data of the laser sensor, whether the pallet is in a state of sliding relative to the forks, and when the pallet is in a state of sliding relative to the forks, determines that the pallet has come into contact with the object. A side shift control device for a forklift.

2. a determination unit that determines whether the forks are in contact with or close to the inner wall surface of the pallet that defines the fork holes based on the operating state of the pallet detected by the detection unit; an initial side shift control unit that controls the side shift unit to move the forks toward the center in the left - right direction of the fork holes when the determination unit determines that the forks are in contact with or close to the inner wall surface of the pallet; and the side shift control unit controls the side shift unit to start moving the pallet toward the object side after the control process by the initial side shift control unit is executed. The side shift control device for a forklift according to Claim 1.

3. The side shift control unit controls the side shift unit to stop the movement of the fork toward the object when the determination unit determines that the pallet has come into contact with the object, according to the side shift control device for a forklift according to claim 1 or 2.

Images