Cargo handling control device for forklift

Abstract

To provide a cargo handling control device for a forklift capable of properly inserting a fork into a pallet hole regardless of the presence or absence of a pallet inclination.SOLUTION: A cargo handling control device 1 comprises a pre-insertion determination part 38 to determine whether or not the tip 6a of a fork 6 is in a state before being inserted into a pallet hole 10; a first fork operation control part 39 to control a lift cylinder 7 so that the fork 6 moves up / down toward the center side in the height direction of a pallet 5 if it is determined that the tip 6a of the fork 6 is in the state before being inserted into the pallet hole 10; and a second fork operation control part 40 to control a tilt cylinder 8 so that the fork 6 tilts in a direction following the inner wall surface of an upper wall surface 11 or a lower wall surface 12 of the pallet 5, and to control the lift cylinder 7 so that the fork 6 moves up / down toward the center side in the height direction of the pallet 5 if it is determined that the tip 6a of the fork 6 is in the state after being inserted into the pallet hole 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cargo handling control device for a forklift.

Background Art

[0002] As a cargo handling control device for a forklift, for example, the technology described in Patent Document 1 is known. The cargo handling control device described in Patent Document 1 includes a sensor that detects whether the distance between the insertion portion of the fork and the opposing surface of the insertion hole of the pallet is equal to or less than a predetermined value, and when it is detected by this sensor that the insertion portion has approached the opposing surface until the distance between the insertion portion and the opposing surface of the insertion hole becomes equal to or less than the predetermined value, after executing a stop process for stopping the moving device, a control device that executes an avoidance process for separating the insertion portion from the opposing surface of the insertion hole so that the height position of the insertion portion with respect to the entrance of the insertion hole does not change by controlling the tilting device and the lifting device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above prior art, when unloading a pallet, in order not to change the height position of the fork at the entrance of the insertion hole (pallet hole) of the pallet, the variation in the height position of the fork due to the tilting control of the fork is offset by the lifting control of the fork. However, in an automatically operated forklift, when detecting a pallet and inserting the fork into the pallet hole of the pallet, due to variations in pallet detection, fork control, etc., the fork may not be positioned at the central part in the height direction of the pallet, but may be positioned near the upper wall part or the lower wall part of the pallet. In this case, even though the pallet is not tilted, the tilting control and lifting control of the fork following the inner wall surface of the upper wall part or the lower wall part of the pallet are carried out, which may lead to unloading failure.

[0005] An object of the present invention is to provide a load handling control device for a forklift that can appropriately insert a fork into a pallet hole of a pallet regardless of the presence or absence of tilting of the pallet.

Means for Solving the Problems

[0006] (1) One aspect of the present invention is a cargo handling control device for a forklift having a lift cylinder that raises and lowers a fork for holding a pallet and a tilt cylinder that tilts the fork, the device including: a donation distance detection unit that detects a donation distance, which is the distance from the tip of the fork to the front surface of the pallet; an insertion control unit that controls the forklift so as to insert the fork into the pallet hole of the pallet; an insertion amount calculation unit that calculates the insertion amount of the fork into the pallet hole based on the donation distance detected by the donation distance detection unit and the movement distance of the fork after the processing of the insertion control unit is started; an insertion pre-determination unit that determines whether it is a state before the tip of the fork is inserted into the pallet hole based on the insertion amount of the fork into the pallet hole calculated by the insertion amount calculation unit after the processing of the insertion control unit is started; a first fork operation control unit that controls the lift cylinder so that the fork moves up and down toward the center side in the height direction of the pallet when it is determined by the insertion pre-determination unit that it is a state before the tip of the fork is inserted into the pallet hole after the processing of the insertion control unit is started; and a second fork operation control unit that controls the tilt cylinder so that the fork tilts in a direction following the inner wall surface of the upper wall portion or the lower wall portion of the pallet and controls the lift cylinder so that the fork moves up and down toward the center side in the height direction of the pallet when it is determined by the insertion pre-determination unit that it is a state after the tip of the fork is inserted into the pallet hole after the processing of the insertion control unit is started.

[0007] In such a handling control device, after the donation distance, which is the distance from the tip of the fork to the front surface of the pallet, is detected, a process of controlling the forklift to insert the fork into the pallet hole of the pallet is started. Then, based on the donation distance and the moving distance of the fork, the insertion amount of the fork into the pallet hole is calculated. Then, based on the insertion amount of the fork into the pallet hole, it is determined whether the state is before the tip of the fork is inserted into the pallet hole. If it is determined that the state is before the tip of the fork is inserted into the pallet hole, the lift cylinder is controlled so that the fork moves up and down toward the center side in the height direction of the pallet. If it is determined that the state is after the tip of the fork is inserted into the pallet hole, the tilt cylinder is controlled so that the fork tilts in a direction following the inner wall surface of the upper wall portion or the lower wall portion of the pallet, and the lift cylinder is controlled so that the fork moves up and down toward the center side in the height direction of the pallet. Thus, when the state is before the tip of the fork is inserted into the pallet hole of the pallet, the fork moves up and down toward the center side in the height direction of the pallet. For this reason, even if the fork is displaced from the central portion in the height direction of the pallet due to detection deviation of the pallet or control deviation of the fork, etc., before the tip of the fork is inserted into the pallet hole of the pallet, the height position of the fork is corrected to the center side in the height direction of the pallet. Thereby, regardless of the presence or absence of inclination of the pallet, the fork is appropriately inserted into the pallet hole of the pallet.

[0008] (2) In the above (1), the forklift's cargo handling control device further includes a pallet upper wall detection unit that detects whether the distance from the tip of the fork to the upper wall of the pallet is equal to or less than a predetermined specified value, and a pallet lower wall detection unit that detects whether the distance from the tip of the fork to the lower wall of the pallet is equal to or less than the specified value. When the first fork movement control unit determines that the state is before the tip of the fork is inserted into the pallet hole by the insertion pre-determination unit, if the pallet upper wall detection unit detects that the distance from the tip of the fork to the upper wall of the pallet is equal to or less than the specified value, the lift cylinder is controlled so that the fork descends; if the pallet lower wall detection unit detects that the distance from the tip of the fork to the lower wall of the pallet is equal to or less than the specified value, the lift cylinder is controlled so that the fork ascends. When the second fork movement control unit determines that the state is after the tip of the fork is inserted into the pallet hole by the insertion pre-determination unit, if the pallet upper wall detection unit detects that the distance from the tip of the fork to the upper wall of the pallet is equal to or less than the specified value, the tilt cylinder is controlled so that the fork tilts forward and the lift cylinder is controlled so that the fork ascends; if the pallet lower wall detection unit detects that the distance from the tip of the fork to the lower wall of the pallet is equal to or less than the specified value, the tilt cylinder is controlled so that the fork tilts backward and the lift cylinder is controlled so that the fork descends.

[0009] In such a configuration, when the state is before the tip of the fork is inserted into the pallet hole of the pallet, if it is detected that the distance from the tip of the fork to the upper wall of the pallet is equal to or less than the specified value, the fork descends. When the state is before the tip of the fork is inserted into the pallet hole of the pallet, if it is detected that the distance from the tip of the fork to the lower wall of the pallet is equal to or less than the specified value, the fork ascends. Therefore, no matter whether the fork is displaced in either the upper or lower direction from the central part in the height direction of the pallet, the height position of the fork will be corrected toward the center side in the height direction of the pallet. Accordingly, regardless of the presence or absence of the inclination of the pallet, the fork can be inserted more appropriately into the pallet hole of the pallet.

[0010] (3) In the above (2), when the first fork operation control unit determines that the state is before the tip of the fork is inserted into the pallet hole by the pre-insertion determination unit, if the distance from the tip of the fork to the upper wall portion of the pallet is detected to be less than or equal to a specified value by the pallet upper wall detection unit, the lift cylinder is controlled so that the fork descends by a certain amount until the pallet upper wall detection unit detects that the distance from the tip of the fork to the upper wall portion of the pallet is not less than or equal to the specified value. When the distance from the tip of the fork to the lower wall portion of the pallet is detected to be less than or equal to a specified value by the pallet lower wall detection unit, the lift cylinder is controlled so that the fork ascends by a certain amount until the pallet lower wall detection unit detects that the distance from the tip of the fork to the lower wall portion of the pallet is not less than or equal to the specified value. When the second fork operation control unit determines that the state is after the tip of the fork is inserted into the pallet hole by the pre-insertion determination unit, if the distance from the tip of the fork to the upper wall portion of the pallet is detected to be less than or equal to a specified value by the pallet upper wall detection unit, the tilt cylinder is controlled so that the fork tilts forward by a certain amount and the lift cylinder is controlled so that the fork ascends by a certain amount until the pallet upper wall detection unit detects that the distance from the tip of the fork to the upper wall portion of the pallet is not less than or equal to the specified value. When the distance from the tip of the fork to the lower wall portion of the pallet is detected to be less than or equal to a specified value by the pallet lower wall detection unit, the tilt cylinder is controlled so that the fork tilts backward by a certain amount and the lift cylinder is controlled so that the fork descends by a certain amount until the pallet lower wall detection unit detects that the distance from the tip of the fork to the lower wall portion of the pallet is not less than or equal to the specified value.

[0011] In such a configuration, when it is detected that the distance from the tip of the fork to the upper wall portion of the pallet is less than or equal to a specified value in a state before the tip of the fork is inserted into the pallet hole of the pallet, the fork descends by a certain amount. When it is detected that the distance from the tip of the fork to the lower wall portion of the pallet is less than or equal to a specified value in a state before the tip of the fork is inserted into the pallet hole of the pallet, the fork ascends by a certain amount. Therefore, even if the fork is displaced in either the upward or downward direction from the central portion in the height direction of the pallet, the height position of the fork will be gradually corrected toward the center side in the height direction of the pallet. Accordingly, regardless of whether the pallet is inclined or not, the fork can be smoothly inserted into the pallet hole of the pallet.

[0012] (4) In any of the above (1) to (3), when the cargo handling control device of the forklift determines by the insertion pre-judgment unit that the state is not before the tip of the fork is inserted into the pallet hole, the forklift further includes an insertion post-judgment unit that determines whether the fork is inserted into the pallet hole by a predetermined specified amount or more. When the first fork operation control unit determines by the insertion post-judgment unit that the fork is not inserted into the pallet hole by the specified amount, the lift cylinder is controlled so that the fork moves up and down toward the center side in the height direction of the pallet. When the second fork operation control unit determines by the insertion post-judgment unit that the fork is inserted into the pallet hole by a specified amount or more, the tilt cylinder is controlled so that the fork tilts in a direction following the inner wall surface of the upper wall portion or the lower wall portion of the pallet, and the lift cylinder may be controlled so that the fork moves up and down toward the center side in the height direction of the pallet.

[0013] In such a configuration, when chamfered portions are provided on the inner wall surfaces of the upper wall portion and the lower wall portion at the open end of the pallet, even in a state after the tip of the fork is inserted into the pallet hole of the pallet, until the fork is inserted to a position beyond the chamfered portion, only the lifting control of the fork is performed and the tilting control of the fork is not performed, so that the fork is less likely to hit the upper wall portion or the lower wall portion of the pallet. Therefore, regardless of whether the pallet is tilted or not, the fork can be more appropriately inserted into the pallet hole of the pallet.

[0014] (5) In any of the above (1) to (4), the insertion control unit controls the forklift so that the forklift travels and inserts the fork into the pallet hole, the insertion amount calculation unit acquires the travel distance of the forklift as the movement distance of the fork, and based on the donation distance detected by the donation distance detection unit and the travel distance of the forklift, the insertion amount of the fork into the pallet hole may be calculated.

[0015] In such a configuration, the movement amount of the fork can be easily obtained as the travel distance of the forklift. Further, by using the distance from the tip of the fork to the front surface of the pallet (donation distance) and the travel distance of the forklift, the insertion amount of the fork into the pallet hole of the pallet can be calculated by a simple calculation formula, so that the processing can be simplified.

Effect of the Invention

[0016] According to the present invention, regardless of whether the pallet is tilted or not, the fork can be appropriately inserted into the pallet hole of the pallet.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

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Figure 6

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Figure 8

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Figure 10

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Figure 16

Best Mode 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 descriptions are omitted.

[0019] FIG. 1 is a block diagram showing the configuration of a cargo handling control device for a forklift according to an embodiment of the present invention. In FIG. 1, the cargo handling control device 1 of the present embodiment is mounted on a forklift 2. As shown in FIG. 2, the forklift 2 has a mast 3 and a pair of left and right forks 6 that are attached to the mast 3 via a spacer 4 so as to be movable up and down and hold a pallet 5.

[0020] Further, the forklift 2 has a lift cylinder 7 for raising and lowering the forks 6 and a tilt cylinder 8 for tilting the forks 6 by tilting the mast 3 (see FIG. 1). The forklift 2 may also have a side shift cylinder (not shown) for moving the forks 6 in the left-right direction (lateral direction).

[0021] The pallet 5 is a cargo handling platform for loading a load M (see FIGS. 7 to 12). The pallet 5 is, for example, a flat pallet. The pallet 5 has a substantially rectangular shape in plan view. The pallet 5 is placed on a loading platform 9 such as a truck or the ground. The pallet 5 is provided with two pallet holes 10 into which the respective forks 6 are inserted. The pallet 5 has an upper wall portion 11 and a lower wall portion 12 that form the pallet holes 10. Inner wall surfaces 11a and 12a facing each other are provided on the upper wall portion 11 and the lower wall portion 12, respectively.

[0022] The cargo handling control device 1 is a device that automatically performs loading and unloading of the pallet 5 by the forklift 2. The cargo handling control device 1 inserts the forks 6 into the pallet holes 10 of the pallet 5 and lifts the pallet 5 by the forks 6 in that state.

[0023] The load handling control device 1 includes a laser sensor 21, a map storage unit 22, a laser sensor 23, a vehicle speed sensor 24, a limit switch 25, an upper hole detection sensor 26, a lower hole detection sensor 27, a driving unit 28 for traveling, a driving unit 29 for load handling, and a controller 30.

[0024] The laser sensor 21 irradiates a laser toward the surroundings of the forklift 2 and receives the reflected light of the laser, thereby detecting the distance to an object existing in the surroundings of the forklift 2 and acquiring point cloud data. The point cloud is a collection of laser reflection points. The horizontal irradiation range of the laser by the laser sensor 21 is 360 degrees. As the laser sensor, for example, a 3D LIDAR or the like is used.

[0025] The map storage unit 22 stores map data of the area where the forklift 2 travels. The map data includes buildings, columns, shelves, walls, and the like. The map data is created in advance using the laser sensor 21.

[0026] The laser sensor 23 irradiates a laser toward the front of the forklift 2 and receives the reflected light of the laser, thereby detecting the distance to an object existing in the front of the forklift 2 and acquiring point cloud data. The objects existing in the front of the forklift 2 include the pallet 5. The horizontal irradiation range of the laser by the laser sensor 23 is a specified angle narrower than the horizontal irradiation range of the laser by the laser sensor 21.

[0027] The vehicle speed sensor 24 detects the traveling speed of the forklift 2. The limit switch 25 is attached to the spacer 4 although not shown in the figure. The limit switch 25 detects contact with the pallet 5 after the insertion of the fork 6 into the pallet hole 10 of the pallet 5 is started. When the limit switch 25 comes into contact with the front surface 5a of the pallet 5, it outputs an ON signal as a detection signal.

[0028] As shown in FIG. 3, the upper hole detection sensor 26 and the lower hole detection sensor 27 are arranged vertically inside the tip of the fork 6. As the upper hole detection sensor 26 and the lower hole detection sensor 27, for example, a reflective photoelectric sensor that irradiates 1D light is used.

[0029] The upper hole detection sensor 26 is a sensor that detects whether the tip 6a of the fork 6 is close to the upper wall portion 11 of the pallet 5. The upper hole detection sensor 26 constitutes a pallet upper wall detection portion that detects whether the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value. The upper hole detection sensor 26 outputs an ON signal as a detection signal when the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than the specified value. The specified value is, for example, about several millimeters.

[0030] The lower hole detection sensor 27 is a sensor that detects whether the tip 6a of the fork 6 is close to the lower wall portion 12 of the pallet 5. The lower hole detection sensor 27 constitutes a pallet lower wall detection portion that detects whether the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value. The lower hole detection sensor 27 outputs an ON signal as a detection signal when the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than the specified value. The specified value is the same as that of the upper hole detection sensor 26.

[0031] The traveling drive unit 28 is a drive unit that drives the forklift 2 to travel. The traveling drive unit 28 has, for example, although not shown in the figure, a traveling motor that rotates the front wheels 16 (see FIG. 2), which are drive wheels, and a steering motor that steers the rear wheels, which are steering wheels.

[0032] The handling drive unit 29 is a drive unit that operates handling hydraulic actuators such as the lift cylinder 7 and the tilt cylinder 8. The handling drive unit 29 is, for example, although not shown in the figure, an oil control valve arranged between the hydraulic pump and the lift cylinder 7 and the tilt cylinder 8.

[0033] The controller 30 is composed of a CPU, a RAM, a ROM, an input / output interface, etc. The controller 30 includes a self-position estimation unit 31, a pallet detection unit 32, a path generation unit 33, a guidance control unit 34, a docking distance calculation unit 35, an insertion travel control unit 36, an insertion amount calculation unit 37, a pre-insertion determination unit 38, a first fork operation control unit 39, a second fork operation control unit 40, and a load handling control unit 41.

[0034] The self-position estimation unit 31 estimates the self-position of the forklift 2 based on the point cloud data of the laser sensor 21 and the map data stored in the map storage unit 22. Specifically, the self-position estimation unit 31 estimates the self-position of the forklift 2 by, for example, using the SLAM (simultaneous localization and mapping) method to match the point cloud data of the laser sensor 21 and the map data. SLAM is a self-position estimation technology that performs self-position estimation using sensor data and map data.

[0035] The pallet detection unit 32 detects the position and orientation of the pallet 5 with respect to the forklift 2 based on the point cloud data of the laser sensor 23, and calculates an insertion start position at which the fork 6 can be inserted into the pallet hole 10 of the pallet 5. The insertion start position is a position in front of the pallet 5 where the tip 6a of the fork 6 faces the pallet hole 10 of the pallet 5.

[0036] The path generation unit 33 generates a travel path from the current position of the forklift 2 estimated by the self-position estimation unit 31 to the insertion start position calculated by the pallet detection unit 32.

[0037] The guidance control unit 34 controls the travel drive unit 28 to guide the forklift 2 to the insertion start position along the travel path generated by the path generation unit 33 based on the self-position of the forklift 2 estimated by the self-position estimation unit 31.

[0038] After the forklift 2 reaches the insertion start position, the donation distance calculation unit 35 calculates a donation distance S, which is the distance from the tip 6a of the fork 6 to the front surface 5a of the pallet 5, based on the point cloud data of the laser sensor 23 and the vehicle specifications of the forklift 2. The donation distance calculation unit 35 constitutes a donation distance detection unit that detects the donation distance S in cooperation with the laser sensor 23.

[0039] At this time, as shown in Fig. 2(a), the distance A from the forklift 2 to the front surface 5a of the pallet 5 is detected by the laser sensor 23 with the central axis G of the front wheel 16 as the origin. Therefore, the donation distance calculation unit 35 calculates the donation distance S by subtracting the distance B between the central axis G of the front wheel 16 and the front surface 3a of the mast 3, the length C of the spacer 4, and the length D of the fork 6 from the distance A from the forklift 2 to the front surface 5a of the pallet 5.

[0040] After the donation distance S is calculated by the donation distance calculation unit 35, the insertion travel control unit 36 controls the travel drive unit 28 so that the fork 6 is inserted into the pallet hole 10 of the pallet 5. The insertion travel control unit 36 constitutes an insertion control unit that controls the forklift 2 so that the fork 6 is inserted into the pallet hole 10 of the pallet 5.

[0041] After starting the process of the insertion travel control unit 36, the insertion amount calculation unit 37 calculates an insertion amount P of the fork 6 into the pallet hole 10 of the pallet 5 based on the donation distance S calculated by the donation distance calculation unit 35 and the movement distance of the fork 6. As shown in Fig. 2(b), the insertion amount calculation unit 37 acquires the travel distance R of the forklift 2 as the movement distance of the fork 6, and calculates the insertion amount P of the fork 6 into the pallet hole 10 based on the donation distance S and the travel distance R of the forklift 2.

[0042] After starting the process of the insertion travel control unit 36, the pre-insertion determination unit 38 determines whether the tip 6a of the fork 6 is in a state before being inserted into the pallet hole 10 of the pallet 5 based on the insertion amount P of the fork 6 into the pallet hole 10 of the pallet 5 calculated by the insertion amount calculation unit 37.

[0043] After the insertion travel control unit 36 starts its processing, when the insertion front determination unit 38 determines that the state is before the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, the first fork operation control unit 39 controls the lift cylinder 7 via the handling drive unit 29 so that the fork 6 moves up and down toward the center side in the height direction of the pallet 5.

[0044] Specifically, when the insertion front determination unit 38 determines that the state is before the tip 6a of the fork 6 is inserted into the pallet hole 10, and when the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value, the first fork operation control unit 39 controls the lift cylinder 7 via the handling drive unit 29 so that the fork 6 moves down. When the insertion front determination unit 38 determines that the state is before the tip 6a of the fork 6 is inserted into the pallet hole 10, and when the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value, the first fork operation control unit 39 controls the lift cylinder 7 via the handling drive unit 29 so that the fork 6 moves up.

[0045] More specifically, when the insertion front determination unit 38 determines that the state is before the tip 6a of the fork 6 is inserted into the pallet hole 10, and when the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is less than or equal to a specified value, the first fork operation control unit 39 controls the lift cylinder 7 via the cargo handling drive unit 29 so that the fork 6 descends by a certain amount until the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is not less than or equal to the specified value. When the insertion front determination unit 38 determines that the state is before the tip 6a of the fork 6 is inserted into the pallet hole 10, and when the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is less than or equal to a specified value, the first fork operation control unit 39 controls the lift cylinder 7 via the cargo handling drive unit 29 so that the fork 6 ascends by a certain amount until the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is not less than or equal to the specified value.

[0046] When the insertion rear determination unit 38 determines that the state is after the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, the second fork operation control unit 40 controls the tilt cylinder 8 via the cargo handling drive unit 29 so that the fork 6 tilts in a direction following the inner wall surface 11a of the upper wall portion 11 or the inner wall surface 12a of the lower wall portion 12 of the pallet 5, and at the same time, controls the lift cylinder 7 via the cargo handling drive unit 29 so that the fork 6 moves up and down toward the center side in the height direction of the pallet 5.

[0047] Specifically, when the insertion front determination unit 38 determines that the state is after the tip 6a of the fork 6 has been inserted into the pallet hole 10, and when the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is less than or equal to a specified value, the second fork operation control unit 40 controls the tilt cylinder 8 via the handling drive unit 29 so that the fork 6 tilts forward, and controls the lift cylinder 7 via the handling drive unit 29 so that the fork 6 rises. When the insertion front determination unit 38 determines that the state is after the tip 6a of the fork 6 has been inserted into the pallet hole 10, and when the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is less than or equal to a specified value, the second fork operation control unit 40 controls the tilt cylinder 8 via the handling drive unit 29 so that the fork 6 tilts backward, and controls the lift cylinder 7 via the handling drive unit 29 so that the fork 6 descends.

[0048] More specifically, when the insertion front determination unit 38 determines that the state is after the tip 6a of the fork 6 has been inserted into the pallet hole 10, and when the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value, the second fork operation control unit 40 controls the tilt cylinder 8 via the cargo handling drive unit 29 so that the fork 6 tilts forward by a certain amount until the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is not equal to or less than the specified value, and controls the lift cylinder 7 via the cargo handling drive unit 29 so that the fork 6 rises by a certain amount. When the insertion front determination unit 38 determines that the state is after the tip 6a of the fork 6 has been inserted into the pallet hole 10, and when the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value, the second fork operation control unit 40 controls the tilt cylinder 8 via the cargo handling drive unit 29 so that the fork 6 tilts backward by a certain amount until the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is not equal to or less than the specified value, and controls the lift cylinder 7 via the cargo handling drive unit 29 so that the fork 6 descends by a certain amount.

[0049] After the insertion of the fork 6 into the pallet hole 10 of the pallet 5 is completed by the second fork operation control unit 40, the cargo handling control unit 41 controls the lift cylinder 7 via the cargo handling drive unit 29 so that the fork 6 rises to lift the pallet 5.

[0050] FIG. 4 is a flowchart showing the procedure of the fork insertion control process executed by the controller 30. This process is executed by the insertion travel control unit 36, the insertion amount calculation unit 37, the insertion front determination unit 38, the first fork operation control unit 39, and the second fork operation control unit 40 after the process of the insertion travel control unit 36 is started.

[0051] Note that at the start of this process, both the forward tilt count value and the backward tilt count value are set to 0. The forward tilt count value is the value indicating the forward tilt amount of the fork 6. When the forward tilt count value is 0, the fork 6 is in a state where it has not tilted forward. The larger the forward tilt count value, the greater the forward tilt amount of the fork 6. The backward tilt count value is the value indicating the backward tilt amount of the fork 6. When the backward tilt count value is 0, the fork 6 is in a state where it has not tilted backward. The larger the backward tilt count value, the greater the backward tilt amount of the fork 6.

[0052] In FIG. 4, the controller 30 first acquires the detected value of the vehicle speed sensor 24 (step S101). Then, the controller 30 calculates the travel distance R of the forklift 2 from the insertion start position (described above) based on the detected value of the vehicle speed sensor 24 (step S102). At this time, the controller 30 calculates the travel distance R of the forklift 2 by integrating the travel speed and travel time of the forklift 2.

[0053] Subsequently, the controller 30 calculates the insertion amount P of the fork 6 into the pallet hole 10 of the pallet 5 based on the donation distance S calculated by the donation distance calculation unit 35 and the travel distance R of the forklift 2 (step S103). At this time, as shown in FIG. 2(b), the controller 30 calculates the insertion amount P of the fork 6 by the following formula. Insertion amount P = Travel distance R - Donation distance S

[0054] Subsequently, the controller 30 acquires the detection signals of the upper hole detection sensor 26 and the lower hole detection sensor 27 (step S104). Then, the controller 30 determines whether the tip 6a of the fork 6 is in a state close to the upper wall portion 11 of the pallet 5 based on the detection signal of the upper hole detection sensor 26 (step S105). The state where the tip 6a of the fork 6 is close to the upper wall portion 11 of the pallet 5 means that if the forklift 2 travels as it is, there is a high possibility that the tip 6a of the fork 6 will hit the upper wall portion 11 of the pallet 5.

[0055] When the controller 30 determines that the tip 6a of the fork 6 is in a state close to the upper wall portion 11 of the pallet 5, it executes the upper proximity fork operation control process (step S106).

[0056] FIG. 5 is a flowchart showing the details of the procedure of the upper proximity fork operation control process. In FIG. 5, the controller 30 first determines whether the tip 6a of the fork 6 is in a state before being inserted into the pallet hole 10 of the pallet 5 based on the insertion amount P of the fork 6 with respect to the pallet hole 10 of the pallet 5 calculated in step S103 (step S201).

[0057] At this time, when the insertion amount P of the fork 6 is negative (-), it is determined that the tip 6a of the fork 6 is in a state before being inserted into the pallet hole 10 of the pallet 5. When the insertion amount P of the fork 6 is positive (+), it is determined that the tip 6a of the fork 6 is in a state after being inserted into the pallet hole 10 of the pallet 5.

[0058] When the controller 30 determines that the tip 6a of the fork 6 is in a state before being inserted into the pallet hole 10, it controls the handling drive unit 29 to lower the fork 6 by a predetermined distance (step S202). The lowering distance is, for example, several millimeters and is set according to the height dimension of the pallet 5.

[0059] When the controller 30 determines that the tip 6a of the fork 6 is not in a state before being inserted into the pallet hole 10, it controls the handling drive unit 29 to tilt the fork 6 forward by a predetermined angle (step S203). The forward tilt angle is, for example, several degrees and is set according to the vertical and horizontal dimensions and the height dimension of the pallet 5. Then, the controller 30 increments the forward tilt count value by 1 (step S204).

[0060] Also, the controller 30 controls the handling drive unit 29 to raise the fork 6 by a predetermined distance (step S205). The raising distance is, for example, equal to the lowering distance in step S202.

[0061] Returning to FIG. 4, when the controller 30 determines that the tip 6a of the fork 6 is not in a state close to the upper wall portion 11 of the pallet 5 in step S105, based on the detection signal of the lower hole detection sensor 27, it determines whether the tip 6a of the fork 6 is in a state close to the lower wall portion 12 of the pallet 5 (step S107). The state where the tip 6a of the fork 6 is close to the lower wall portion 12 of the pallet 5 means that if the forklift 2 travels as it is, there is a high possibility that the tip 6a of the fork 6 will hit the lower wall portion 12 of the pallet 5.

[0062] When the controller 30 determines that the tip 6a of the fork 6 is in a state close to the lower wall portion 12 of the pallet 5, it executes the lower proximity fork operation control process (step S108).

[0063] FIG. 6 is a flowchart showing the details of the procedure of the lower proximity fork operation control process. In FIG. 6, the controller 30 first determines whether the tip 6a of the fork 6 is in a state before being inserted into the pallet hole 10 of the pallet 5 based on the insertion amount P of the fork 6 with respect to the pallet hole 10 of the pallet 5 calculated in step S103 (step S211).

[0064] When the controller 30 determines that the tip 6a of the fork 6 is in a state before being inserted into the pallet hole 10, it controls the cargo handling drive unit 29 to raise the fork 6 by a predetermined distance (step S212). The raising distance is, for example, equal to the lowering distance in step S202.

[0065] When the controller 30 determines that the tip 6a of the fork 6 is not in a state before being inserted into the pallet hole 10, it controls the cargo handling drive unit 29 to tilt the fork 6 backward by a predetermined angle (step S213). The backward tilt angle is, for example, equal to the forward tilt angle in step S203. Then, the controller 30 adds 1 to the backward tilt count value (step S214).

[0066] Further, the controller 30 controls the handling drive unit 29 so as to lower the fork 6 by a predetermined distance (step S215). The lowering distance is equal to, for example, the lowering distance in step S202.

[0067] Returning to FIG. 4, when the controller 30 determines that the tip 6a of the fork 6 is not in a state close to the lower wall portion 12 of the pallet 5 in step S107, the controller 30 determines whether or not the forward tilt count value is not zero (step S109).

[0068] When the controller 30 determines that the forward tilt count value is not zero, the controller 30 controls the handling drive unit 29 so as to lower the fork 6 by a distance corresponding to the forward tilt count value (step S110). At this time, the larger the forward tilt count value, the longer the lowering distance of the fork 6.

[0069] When the controller 30 determines that the forward tilt count value is zero, the controller 30 determines whether or not the backward tilt count value is not zero (step S111). When the controller 30 determines that the backward tilt count value is not zero, the controller 30 controls the handling drive unit 29 so as to raise the fork 6 by a distance corresponding to the backward tilt count value (step S112). At this time, the larger the backward tilt count value, the longer the raising distance of the fork 6.

[0070] After the controller 30 executes any one of steps S106, S108, S110, and S112, or when the controller 30 determines that the backward tilt count value is zero in step S111, the controller 30 acquires the detection signal of the limit switch 25 (step S113). Then, the controller 30 determines whether or not the insertion of the fork 6 into the pallet hole 10 of the pallet 5 is completed based on the detection signal of the limit switch 25 (step S114).

[0071] When the controller 30 determines that the insertion of the fork 6 into the pallet hole 10 of the pallet 5 is not completed, the above-described procedure S101 is executed again. When the controller 30 determines that the insertion of the fork 6 into the pallet hole 10 of the pallet 5 is completed, the running drive unit 28 is controlled to stop the running of the forklift 2 (procedure S115), and this process is terminated.

[0072] Here, the insertion travel control unit 36 executes the above-described procedures S113 to S115. The insertion amount calculation unit 37 executes the above-described procedures S101 to S103. The pre-insertion determination unit 38 executes the above-described procedures S201 and S211. The first fork operation control unit 39 executes the above-described procedures S105, S107, S202, and S212. The second fork operation control unit 40 executes the above-described procedures S105, S107, S203 to S205, S213 to S215, S109 to S112.

[0073] In the cargo handling control device 1 as described above, when unloading the pallet 5, the forklift 2 moves forward so that the fork 6 is inserted into the pallet hole 10 of the pallet 5 from the insertion start position (described above).

[0074] Here, as shown in FIG. 7(a), before the fork 6 is inserted into the pallet hole 10 of the pallet 5 placed on a flat ground without inclination, when it is detected by the upper hole detection sensor 26 that the tip 6a of the fork 6 is in a state close to the upper wall portion 11 of the pallet 5, as shown in FIG. 7(b), the fork 6 descends toward the central portion in the height direction of the pallet 5. And in that state, as shown in FIG. 7(c), the fork 6 is inserted into the pallet hole 10 of the pallet 5. Therefore, it is possible to prevent the tip 6a of the fork 6 from hitting the upper wall portion 11 of the pallet 5.

[0075] Also, as shown in Fig. 8(a), before the fork 6 is inserted into the pallet hole 10 of the pallet 5 placed on the flat loading platform 9 without inclination, when it is detected by the lower hole detecting sensor 27 that the tip 6a of the fork 6 is in a state close to the lower wall portion 12 of the pallet 5, as shown in Fig. 8(b), the fork 6 rises toward the central portion in the height direction of the pallet 5. And in that state, as shown in Fig. 8(c), the fork 6 is inserted into the pallet hole 10 of the pallet 5. Therefore, it is possible to prevent the tip 6a of the fork 6 from hitting the lower wall portion 12 of the pallet 5.

[0076] Also, as shown in Fig. 9(a), before the fork 6 is inserted into the pallet hole 10 of the pallet 5 placed on the inclined loading platform 9 where the front side is higher than the back side, when it is detected by the upper hole detecting sensor 26 that the tip 6a of the fork 6 is in a state close to the upper wall portion 11 of the pallet 5, as shown in Fig. 9(b), the fork 6 descends toward the central portion in the height direction of the pallet 5. And in that state, as shown in Fig. 9(c), the fork 6 is inserted into the pallet hole 10 of the pallet 5. Therefore, it is possible to prevent the tip 6a of the fork 6 from hitting the upper wall portion 11 of the pallet 5.

[0077] And, as shown in Fig. 10(a), after the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, when it is detected by the upper hole detecting sensor 26 that the tip 6a of the fork 6 is in a state close to the upper wall portion 11 of the pallet 5, as shown in Fig. 10(b), the fork 6 tilts forward so as to approach parallel to the inner wall surface 11a of the upper wall portion 11 of the pallet 5. Also, as shown in Fig. 10(c), the fork 6 rises.

[0078] After that, the forklift 2 travels while gradually lowering the fork 6 until the insertion of the fork 6 is completed. Therefore, in a state where the fork 6 is tilted forward, it is possible to prevent the tip 6a of the fork 6 from hitting the upper wall portion 11 of the pallet 5.

[0079] Also, as shown in Fig. 11(a), before the fork 6 is inserted into the pallet hole 10 of the pallet 5 placed on the inclined loading platform 9 where the front side is lower than the back side, when it is detected by the lower hole detection sensor 27 that the tip 6a of the fork 6 is in a state close to the lower wall portion 12 of the pallet 5, as shown in Fig. 11(b), the fork 6 rises toward the central portion in the height direction of the pallet 5. And in that state, as shown in Fig. 11(c), the fork 6 is inserted into the pallet hole 10 of the pallet 5. Therefore, it is possible to prevent the tip 6a of the fork 6 from hitting the lower wall portion 12 of the pallet 5.

[0080] And, as shown in Fig. 12(a), after the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, when it is detected by the lower hole detection sensor 27 that the tip 6a of the fork 6 is in a state close to the lower wall portion 12 of the pallet 5, as shown in Fig. 12(b), the fork 6 tilts backward so as to approach parallel to the inner wall surface 12a of the lower wall portion 12 of the pallet 5. Also, as shown in Fig. 12(c), the fork 6 descends.

[0081] Thereafter, the forklift 2 travels while gradually raising the fork 6 until the insertion of the fork 6 is completed. Therefore, in a state where the fork 6 is tilted backward, it is possible to prevent the tip 6a of the fork 6 from hitting the lower wall portion 12 of the pallet 5.

[0082] As described above, in the present embodiment, after the donation distance S, which is the distance from the tip 6a of the fork 6 to the front surface 5a of the pallet 5, is detected, the process of controlling the fork lift 2 to insert the fork 6 into the pallet hole 10 of the pallet 5 is started. Then, based on the donation distance S and the moving distance of the fork 6, the insertion amount P of the fork 6 into the pallet hole 10 is calculated. Then, based on the insertion amount P of the fork 6 into the pallet hole 10, it is determined whether the state is before the tip 6a of the fork 6 is inserted into the pallet hole 10. When it is determined that the state is before the tip 6a of the fork 6 is inserted into the pallet hole 10, the lift cylinder 7 is controlled so that the fork 6 moves up and down toward the center side in the height direction of the pallet 5. When it is determined that the state is after the tip 6a of the fork 6 is inserted into the pallet hole 10, the tilt cylinder 8 is controlled so that the fork 6 tilts in a direction following the inner wall surface 11a of the upper wall portion 11 or the inner wall surface 12a of the lower wall portion 12 of the pallet 5, and the lift cylinder 7 is controlled so that the fork 6 moves up and down toward the center side in the height direction of the pallet 5. Thus, when the state is before the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, the fork 6 moves up and down toward the center side in the height direction of the pallet 5. For this reason, even if the fork 6 is displaced from the central portion in the height direction of the pallet 5 due to a detection deviation of the pallet 5 or a control deviation of the fork 6 or the like, before the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, the height position of the fork 6 is corrected toward the center side in the height direction of the pallet 5. As a result, regardless of the presence or absence of the inclination of the pallet 5, the fork 6 is appropriately inserted into the pallet hole 10 of the pallet 5. As a result, false detection of the inclination of the pallet 5 can be suppressed, and failure of loading and unloading of the pallet 5 can be prevented.

[0083] In addition, in the present embodiment, when the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is detected to be equal to or less than a specified value in a state before the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, the fork 6 descends. When the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is detected to be equal to or less than a specified value in a state before the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, the fork 6 ascends. Therefore, even if the fork 6 is displaced in either the upward or downward direction from the central portion in the height direction of the pallet 5, the height position of the fork 6 is corrected toward the center side in the height direction of the pallet 5. Accordingly, regardless of whether the pallet 5 is inclined or not, the fork 6 is more appropriately inserted into the pallet hole 10 of the pallet 5.

[0084] In addition, in the present embodiment, when the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is detected to be equal to or less than a specified value in a state before the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, the fork 6 descends by a certain amount at a time. When the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is detected to be equal to or less than a specified value in a state before the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, the fork 6 ascends by a certain amount at a time. Therefore, even if the fork 6 is displaced in either the upward or downward direction from the central portion in the height direction of the pallet 5, the height position of the fork 6 is gradually corrected toward the center side in the height direction of the pallet 5. Accordingly, regardless of whether the pallet 5 is inclined or not, the fork 6 is smoothly inserted into the pallet hole 10 of the pallet 5.

[0085] In addition, in the present embodiment, the movement amount of the fork 6 can be easily obtained as the travel distance R of the forklift 2. Further, by using the distance (attachment distance S) from the tip 6a of the fork 6 to the front surface 5a of the pallet 5 and the travel distance R of the forklift 2, the insertion amount P of the fork 6 into the pallet hole 10 of the pallet 5 can be calculated by a simple calculation formula, so that the processing can be simplified.

[0086] FIG. 13 is a block diagram showing the configuration of a cargo handling control device for a forklift according to another embodiment of the present invention. In FIG. 13, the cargo handling control device 1A of the present embodiment includes a controller 30A instead of the controller 30 in the above embodiment.

[0087] The controller 30A includes a self-position estimation unit 31, a pallet detection unit 32, a path generation unit 33, a guidance control unit 34, an insertion distance calculation unit 35, an insertion travel control unit 36, an insertion amount calculation unit 37, a pre-insertion determination unit 38, a post-insertion determination unit 50, a first fork operation control unit 39A, a second fork operation control unit 40A, and a cargo handling control unit 41.

[0088] When the post-insertion determination unit 50 determines that the state is not before the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5 by the pre-insertion determination unit 38, the post-insertion determination unit 50 determines whether the fork 6 is inserted into the pallet hole 10 by a predetermined amount or more.

[0089] For example, as shown in FIG. 14, when chamfered portions 51 are provided on the inner wall surface 11a of the upper wall portion 11 and the inner wall surface 12a of the lower wall portion 12 at the opening end portion of the pallet 5, respectively, the predetermined amount is the length dimension L of the chamfered portion 51. The chamfered portion 51 is formed in an R shape or a tapered shape such that the pallet hole 10 tapers inward from the opening end surface 5b of the pallet 5.

[0090] When the first fork operation control unit 39A determines that the fork 6 is not inserted into the pallet hole 10 of the pallet 5 by a predetermined amount or more by the post-insertion determination unit 50, the first fork operation control unit 39A controls the lift cylinder 7 via the cargo handling drive unit 29 so that the fork 6 moves up and down toward the center in the height direction of the pallet 5.

[0091] When the insertion post-determination unit 50 determines that the fork 6 has been inserted into the pallet hole 10 of the pallet 5 by a specified amount or more, the second fork operation control unit 40A controls the tilt cylinder 8 via the handling drive unit 29 so that the fork 6 tilts in a direction following the inner wall surface 11a of the upper wall portion 11 or the inner wall surface 12a of the lower wall portion 12 of the pallet 5, and controls the lift cylinder 7 via the handling drive unit 29 so that the fork 6 moves up and down toward the center in the height direction of the pallet 5.

[0092] FIG. 15 is a flowchart showing a modified example of the procedure of the upper proximity fork operation control process shown in FIG. 5. In FIG. 15, when the controller 30A determines in step S201 that the state is not before the fork 6 is inserted into the pallet hole 10 of the pallet 5, it determines whether the fork 6 has been inserted into the pallet hole 10 by a specified amount or more based on the insertion amount P of the fork 6 calculated in step S103 of FIG. 4 (step S208).

[0093] When the controller 30A determines that the fork 6 has not been inserted into the pallet hole 10 by a specified amount or more, it executes step S202. When the controller 30A determines that the fork 6 has been inserted into the pallet hole 10 by a specified amount or more, it executes step S203.

[0094] FIG. 16 is a flowchart showing a modified example of the procedure of the lower proximity fork operation control process shown in FIG. 6. In FIG. 16, when the controller 30A determines in step S211 that the state is not before the fork 6 is inserted into the pallet hole 10 of the pallet 5, it determines whether the fork 6 has been inserted into the pallet hole 10 by a specified amount or more based on the insertion amount P of the fork 6 calculated in step S103 of FIG. 4 (step S218).

[0095] When the controller 30A determines that the fork 6 has not been inserted into the pallet hole 10 by a specified amount or more, it executes step S212. When the controller 30A determines that the fork 6 has been inserted into the pallet hole 10 by a specified amount or more, it executes step S213.

[0096] In the present embodiment as described above, when the chamfered portions 51 are provided on the inner wall surface 11a of the upper wall portion 11 and the inner wall surface 12a of the lower wall portion 12 at the opening end of the pallet 5, even in the state after the tip 6a of the fork 6 is inserted into the pallet hole 10 of the pallet 5, until the fork 6 is inserted to a position beyond the chamfered portion 51, only the lifting control of the fork 6 is performed and the tilting control of the fork 6 is not performed, so that it is less likely that the fork 6 hits the upper wall portion 11 or the lower wall portion 12 of the pallet 5. Therefore, regardless of whether the pallet 5 is inclined or not, the fork 6 is more appropriately inserted into the pallet hole 10 of the pallet 5.

[0097] Note that the present invention is not limited to the above embodiment. For example, in the above embodiment, when it is detected by the upper hole detecting sensor 26 that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value, the fork 6 is lowered by a certain amount to the central portion in the height direction of the pallet 5, but it is not particularly limited to such a form. For example, when it is detected by the upper hole detecting sensor 26 that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value, the fork 6 is lowered until it is detected by the lower hole detecting sensor 27 that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value, and then the fork 6 may be raised to the central portion in the height direction of the pallet 5.

[0098] Also, in the above embodiment, when it is detected by the lower hole detecting sensor 27 that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value, the fork 6 is raised by a certain amount to the central portion in the height direction of the pallet 5, but it is not particularly limited to such a form. For example, when it is detected by the lower hole detecting sensor 27 that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value, the fork 6 is raised until it is detected by the upper hole detecting sensor 26 that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value, and then the fork 6 may be lowered to the central portion in the height direction of the pallet 5.

[0099] Also, in the above embodiment, when the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value, the fork 6 is tilted forward little by little so as to be parallel to the pallet 5. However, the form is not particularly limited to such a form. For example, when the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value, the fork 6 is tilted forward until the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value, and then the fork 6 may be tilted backward so as to be parallel to the pallet 5.

[0100] Also, in the above embodiment, when the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value, the fork 6 is tilted backward little by little so as to be parallel to the pallet 5. However, the form is not particularly limited to such a form. For example, when the lower hole detection sensor 27 detects that the distance from the tip 6a of the fork 6 to the lower wall portion 12 of the pallet 5 is equal to or less than a specified value, the fork 6 is tilted backward until the upper hole detection sensor 26 detects that the distance from the tip 6a of the fork 6 to the upper wall portion 11 of the pallet 5 is equal to or less than a specified value, and then the fork 6 may be tilted forward so as to be parallel to the pallet 5.

[0101] Also, in the above embodiment, the donation distance S, which is the distance from the tip 6a of the fork 6 to the front surface 5a of the pallet 5, is detected using the laser sensor 23. However, the sensor used for detecting the donation distance S is not particularly limited to the laser sensor 23, and a ToF camera or the like may be used, or the above-described laser sensor 21 for self-position estimation may also be used.

[0102] In the above-described embodiment, the traveling distance R of the forklift 2 is calculated by integrating the traveling speed and the traveling time detected by the vehicle speed sensor 24. However, the form is not particularly limited thereto, and the traveling distance R of the forklift 2 may be detected by an odometry sensor or the like.

[0103] In the above-described embodiment, when the forklift 2 travels forward, the fork 6 is inserted into the pallet hole 10 of the pallet 5. However, the form is not particularly limited thereto. For example, when the forklift 2 is a reach-type forklift, the fork 6 may be inserted into the pallet hole 10 of the pallet 5 by extending the mast 3 by a reach cylinder.

Explanation of reference numerals

[0104] 1, 1A... cargo handling control device, 2... forklift, 5... pallet, 5a... front surface, 6... fork, 6a... tip, 7... lift cylinder, 8... tilt cylinder, 10... pallet hole, 11... upper wall portion, 11a... inner wall surface, 12... lower wall portion, 12a... inner wall surface, 23... laser sensor (donation distance detection unit), 26... upper hole detection sensor (pallet upper wall detection unit), 27... lower hole detection sensor (pallet lower wall detection unit), 35... donation distance calculation unit (donation distance detection unit), 36... insertion travel control unit (insertion control unit), 37... insertion amount calculation unit, 38... pre-insertion determination unit, 39, 39A... first fork operation control unit, 40, 40A... second fork operation control unit, 50... post-insertion determination unit, P... insertion amount, R... travel distance, S... donation distance.

Claims

1. A cargo handling control device for a forklift having a lift cylinder for raising and lowering a fork for holding a pallet and a tilt cylinder for tilting the fork, a donation distance detection unit that detects a donation distance, which is the distance from the tip of the fork to the front surface of the pallet, an insertion control unit that controls the forklift so as to insert the fork into the pallet hole of the pallet, an insertion amount calculation unit that calculates an insertion amount of the fork into the pallet hole based on the donation distance detected by the donation distance detection unit and the movement distance of the fork after starting the process of the insertion control unit, a pre-insertion determination unit that determines whether or not it is a state before the tip of the fork is inserted into the pallet hole based on the insertion amount of the fork into the pallet hole calculated by the insertion amount calculation unit after starting the process of the insertion control unit, a first fork operation control unit that controls the lift cylinder so that the fork moves up and down toward the center side in the height direction of the pallet when it is determined by the pre-insertion determination unit that it is a state before the tip of the fork is inserted into the pallet hole after starting the process of the insertion control unit, a second fork operation control unit that controls the tilt cylinder so that the fork tilts in a direction following the inner wall surface of the upper wall portion or the lower wall portion of the pallet and controls the lift cylinder so that the fork moves up and down toward the center side in the height direction of the pallet when it is determined by the pre-insertion determination unit that it is a state after the tip of the fork is inserted into the pallet hole after starting the process of the insertion control unit. A cargo handling control device for a forklift.

2. a pallet upper wall detection unit that detects whether or not the distance from the tip of the fork to the upper wall portion of the pallet is equal to or less than a predetermined specified value, further comprising a pallet lower wall detection unit that detects whether or not the distance from the tip of the fork to the lower wall portion of the pallet is equal to or less than the specified value. When the first fork operation control unit determines that the tip of the fork is in a state before being inserted into the pallet hole by the pre-insertion determination unit, if the distance from the tip of the fork to the upper wall portion of the pallet is detected to be equal to or less than the specified value by the pallet upper wall detection unit, the lift cylinder is controlled so that the fork descends. When the distance from the tip of the fork to the lower wall portion of the pallet is detected to be equal to or less than the specified value by the pallet lower wall detection unit, the lift cylinder is controlled so that the fork ascends. When the second fork operation control unit determines that the tip of the fork is in a state after being inserted into the pallet hole by the pre-insertion determination unit, if the distance from the tip of the fork to the upper wall portion of the pallet is detected to be equal to or less than the specified value by the pallet upper wall detection unit, the tilt cylinder is controlled so that the fork tilts forward and the lift cylinder is controlled so that the fork ascends. When the distance from the tip of the fork to the lower wall portion of the pallet is detected to be equal to or less than the specified value by the pallet lower wall detection unit, the tilt cylinder is controlled so that the fork tilts backward and the lift cylinder is controlled so that the fork descends. The load handling control device for a forklift according to claim 1.

3. When the first fork operation control unit determines that the tip of the fork is in a state before being inserted into the pallet hole by the pre-insertion determination unit, if the distance from the tip of the fork to the upper wall portion of the pallet is detected to be equal to or less than the specified value by the pallet upper wall detection unit, the lift cylinder is controlled so that the fork descends by a certain amount until the distance from the tip of the fork to the upper wall portion of the pallet is detected to be not equal to or less than the specified value by the pallet upper wall detection unit. When the distance from the tip of the fork to the lower wall portion of the pallet is detected to be equal to or less than the specified value by the pallet lower wall detection unit, the lift cylinder is controlled so that the fork ascends by a certain amount until the distance from the tip of the fork to the lower wall portion of the pallet is detected to be not equal to or less than the specified value by the pallet lower wall detection unit. When the second fork operation control unit determines that the state is after the tip of the fork has been inserted into the pallet hole by the pre-insertion determination unit, if the pallet upper wall detection unit detects that the distance from the tip of the fork to the upper wall portion of the pallet is less than or equal to the specified value, the tilt cylinder is controlled so that the fork tilts forward by a certain amount until the pallet upper wall detection unit detects that the distance from the tip of the fork to the upper wall portion of the pallet is not less than or equal to the specified value, and the lift cylinder is controlled so that the fork rises by a certain amount. When the pallet lower wall detection unit detects that the distance from the tip of the fork to the lower wall portion of the pallet is less than or equal to the specified value, the tilt cylinder is controlled so that the fork tilts backward by a certain amount until the pallet lower wall detection unit detects that the distance from the tip of the fork to the lower wall portion of the pallet is not less than or equal to the specified value, and the lift cylinder is controlled so that the fork descends by a certain amount. The load handling control device for a forklift according to claim 2.

4. When the pre-insertion determination unit determines that the state is not before the tip of the fork is inserted into the pallet hole, the forklift further includes a post-insertion determination unit that determines whether the fork has been inserted into the pallet hole by a predetermined specified amount or more. When the post-insertion determination unit determines that the fork has not been inserted into the pallet hole by the specified amount or more, the first fork operation control unit controls the lift cylinder so that the fork moves up and down toward the center side in the height direction of the pallet. When the post-insertion determination unit determines that the fork has been inserted into the pallet hole by the specified amount or more, the second fork operation control unit controls the tilt cylinder so that the fork tilts in a direction following the inner wall surface of the upper wall portion or the lower wall portion of the pallet, and controls the lift cylinder so that the fork moves up and down toward the center side in the height direction of the pallet. The load handling control device for a forklift according to claim 1.

5. The insertion control unit controls the forklift so that the forklift travels and inserts the fork into the pallet hole. The insertion amount calculation unit acquires the travel distance of the forklift as the movement distance of the fork, and calculates the insertion amount of the fork into the pallet hole based on the donation distance detected by the donation distance detection unit and the travel distance of the forklift. The cargo handling control device for a forklift according to claim 1.

Images