Driving control system

Abstract

To provide a traveling control device capable of improving throughput while preventing a forklift from overturning.SOLUTION: A traveling control device for a forklift detects, when a cargo is placed on a fork, a gravity central position of the forklift including the cargo, acquires correspondence information associating a lift height indicating a position of the fork in a vertical direction, a reach length indicating a protrusion amount of the fork in an advancing direction, and acceleration that positions a zero moment point within a stable region on the basis of the gravity central position, acquires the lift height and the reach length, acquires allowable acceleration from the correspondence information on the basis of the acquired lift height and reach length, acquires a target reach length from the correspondence information on the basis of the lift height and maximum acceleration when the allowable acceleration is smaller than the maximum acceleration, drives a cargo device such that the reach length becomes the target reach length, and accelerates the forklift at acceleration greater than the allowable acceleration when the reach length is taken to be the target reach length.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a travel control device.

Background Art

[0002] For example, Patent Document 1 discloses a travel control device for a forklift that calculates an allowable acceleration based on a lifting height detected by a lifting height detector and a load detected by a load detector. This travel control device suppresses overturning of the forklift by controlling an actual acceleration based on the allowable acceleration.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] By the way, in the travel control device described in the above Patent Document 1, the actual acceleration is restricted by the allowable acceleration corresponding to the load. In a logistics facility or the like where a forklift operates, throughput (cargo handling capacity of the forklift) may be higher as the acceleration of the forklift, that is, the moving speed of the forklift, is higher. Therefore, there is a demand for a technique that can improve throughput while suppressing overturning of the forklift.

[0005] The present disclosure has been made to solve the above problem, and an object of the present disclosure is to provide a travel control device that can improve throughput while suppressing overturning of a forklift.

Means for Solving the Problem

[0006] To solve the above problems, the mobility control device according to this disclosure includes a vehicle, a drive wheel provided on the vehicle and driven to move the vehicle, and a device provided on the vehicle that can move together with the vehicle. A pair of rails, which are spaced apart in the width direction of the vehicle and extend in the longitudinal direction of the vehicle. Straddle legs and, A pair of straddle legs are provided with a first driven wheel and a second driven wheel, which are arranged apart from the drive wheels in the front-rear direction, A travel control device for a forklift, comprising a load handling device provided on the straddle leg and driven so that the forks can be raised and lowered vertically and move back and forth in the direction of travel of the vehicle, wherein when a load is placed on the forks, a center of gravity position detection unit detects the center of gravity position of the forklift including the load, a correspondence relationship information acquisition unit acquires correspondence relationship information in which the lifting height indicating the position of the forks in the vertical direction, the reach length indicating the amount the forks protrude in the direction of travel, and the acceleration that positions the zero moment point within a stable region is related to each other based on the center of gravity position, and a load handling device acquires the lifting height and the reach length of the forks The system comprises: a position information acquisition unit; an allowable acceleration acquisition unit that acquires an allowable acceleration from the correspondence relationship information based on the lifting height and reach length acquired by the cargo handling device information acquisition unit; a target reach length acquisition unit that acquires a target reach length from the correspondence relationship information based on the lifting height and maximum acceleration when the allowable acceleration is smaller than the maximum acceleration of the forklift; a cargo handling device drive unit that drives the cargo handling device so that the reach length of the forks becomes the target reach length; and a drive wheel control unit that drives the drive wheels so that the forklift accelerates at an acceleration greater than the allowable acceleration when the reach length of the forks becomes the target reach length. The zero moment point is the intersection of a hypothetical extension of the resultant force vector F+G, which is the vector F representing the direction and magnitude of the inertial force acting on the center of gravity in the opposite direction to the direction of acceleration of the vehicle when the vehicle is accelerating, and a vector G representing the direction and magnitude of gravity acting on the center of gravity, and the road surface on which the vehicle is traveling. The stable region is a region that forms a hypothetical triangle when viewed from above, with its vertices at the positions of the rotation axes extending in the vertical direction of the respective drive wheels, the first driven wheels, and the second driven wheels. .

[0007] Furthermore, the driving control device according to the present disclosure is a driving control device for a forklift comprising: a vehicle; drive wheels provided on the vehicle and driven to move the vehicle; a pair of straddle legs provided on the vehicle and capable of moving together with the vehicle, spaced apart in the vehicle width direction and extending in the longitudinal direction of the vehicle; a first driven wheel and a second driven wheel provided on the pair of straddle legs and spaced apart from the drive wheels in the longitudinal direction; and a load handling device provided on the straddle legs and driven to allow the forks to move up and down in the vertical direction and to move back and forth in the direction of travel of the vehicle, wherein the driving control device includes: a center of gravity position detection unit that detects the center of gravity position of the forklift including the load when a load is placed on the forks; a lifting height indicating the position of the forks in the vertical direction and a lead height indicating the amount of protrusion of the forks in the direction of travel based on the center of gravity position The forklift comprises: a correspondence relationship information acquisition unit that acquires correspondence relationship information relating the reach length and the acceleration that positions the zero moment point within a stable region; a cargo handling device information acquisition unit that acquires the lifting height of the forks when the center of gravity position of the forklift is detected; a target reach length acquisition unit that acquires a target reach length from the correspondence relationship information based on the lifting height of the forks and the maximum acceleration of the forklift acquired by the cargo handling device information acquisition unit; a cargo handling device drive unit that drives the cargo handling device so that the reach length of the forks becomes the target reach length; an allowable acceleration acquisition unit that acquires an allowable acceleration from the correspondence relationship information based on the lifting height of the forks and the target reach length; and a drive wheel control unit that drives the drive wheels so that the forklift accelerates at the allowable acceleration when the reach length of the forks becomes the target reach length. The aforementioned zero moment point is, When the vehicle accelerates, the stable region is the intersection of a hypothetical extension of the resultant force vector F+G, which is the resultant of a vector F representing the direction and magnitude of the inertial force acting on the center of gravity in the opposite direction to the direction of acceleration of the vehicle, and a vector G representing the direction and magnitude of gravity acting on the center of gravity, and the road surface on which the vehicle travels. When viewed from above, the stable region is a region that forms a hypothetical triangle with its vertices at the positions of the rotation axes extending in the vertical direction of the respective drive wheels, the first driven wheels, and the second driven wheels. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a travel control device that can improve throughput while suppressing the tipping of a forklift. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing the overall configuration of a motion control system according to an embodiment of this disclosure. [Figure 2] This is a perspective view showing the configuration of a forklift according to the first embodiment of this disclosure. [Figure 3] This is a conceptual diagram illustrating the zero moment point according to the first embodiment of this disclosure. [Figure 4] This is a functional block diagram of a driving control device according to the first embodiment of the present disclosure. [Figure 5] This is a conceptual diagram illustrating the stable region and the permissible region according to the first embodiment of this disclosure. [Figure 6] This flowchart shows an example of the operation of a driving control device according to the first embodiment of this disclosure. [Figure 7] This flowchart shows an example of the operation of a driving control device according to the first embodiment of this disclosure. [Figure 8] This flowchart shows an example of a cargo handling control step in the operation of a travel control device according to the first embodiment of this disclosure. [Figure 9] A flowchart illustrating an example of the operation of a driving control device according to the second embodiment of this disclosure. [Figure 10] This is a hardware configuration diagram showing the configuration of a computer according to the embodiments of this disclosure. [Figure 11] A flowchart illustrating an example of the operation of a driving control device according to another embodiment of this disclosure. [Modes for carrying out the invention]

[0010] Hereinafter, a movement control system including a travel control device according to an embodiment of the present disclosure will be described with reference to the drawings.

[0011] <First Embodiment> [Movement Control System] The movement control system is a system that controls the movement of a moving body. The movement control system according to the present embodiment controls the movement of a forklift as a moving body that performs cargo handling work such as loading, unloading, and transporting cargo in a logistics facility such as a distribution center or a warehouse, for example.

[0012] Here, as shown in FIG. 1, the forklift 10 according to the present embodiment passes through an aisle when moving cargo from a predetermined position to a target position in the logistics facility LF. The aisle is sandwiched between a pair of opposing walls W and extends in one direction.

[0013] Examples of the wall W in the present embodiment include a rack on which a plurality of cargoes or the like are placed. Hereinafter, the one direction in which the aisle extends will be referred to as "aisle extending direction D1", and the width direction of the aisle, which is the direction in which the pair of walls W face each other, will be referred to as "aisle width direction D2". In the present embodiment, the aisle extending direction D1 and the aisle width direction D2 are directions orthogonal to each other.

[0014] The movement control system 1 includes a forklift 10, a travel control device 20, and a host device 40.

[0015] (Forklift) The forklift 10 is an industrial vehicle that moves cargo placed on a pallet in the logistics facility LF. The forklift 10 according to the present embodiment is a vehicle that travels autonomously in accordance with commands received from the host device 40. The forklift 10 is, for example, a reach-type automated guided forklift (AGF).

[0016] As shown in Figure 2, the forklift 10 in this embodiment includes a vehicle 11, straddle legs 12, a cargo handling device 13, a travel mechanism 14, a weight sensor 15, and a self-position sensor 16.

[0017] (vehicle) Vehicle 11 is the main body of the forklift 10 and travels on the road surface R within the logistics facility LF via the driving mechanism 14. For the sake of explanation, the direction in which this vehicle 11 moves (the direction in which the vehicle 11 moves forward and backward) will be referred to as the "direction of travel Ds". Furthermore, of the two sides of this direction of travel Ds, the forward side will be referred to as the "front side Dsf", and the opposite side, the backward side, will be referred to as the "rear side Dsb".

[0018] Furthermore, the width direction of this vehicle 11 is referred to as the "vehicle width direction Dw". In addition, of the two sides of the vehicle width direction Dw, the right side when viewing the vehicle 11 from the rear side Dsb is referred to as the "one side Dwr", and the opposite side (left side) is referred to as the "other side Dwl".

[0019] (Straddle legs) The straddle legs 12 are integrally provided with the vehicle 11 on the rear side Dsb and lower side of the vehicle 11. The straddle legs 12 are a pair of axial members extending from the vehicle 11 to the rear side Dsb. The pair of straddle legs 12 are spaced apart from each other in the vehicle width direction Dw.

[0020] Hereinafter, of the pair of straddle legs 12, the straddle leg 12 located on one side Dwr will be referred to as the "right straddle leg 121," and the straddle leg 12 located on the opposite side (the other side Dwl) will be referred to as the "left straddle leg 122."

[0021] (Cargo handling equipment) The cargo handling device 13 is the part of the forklift 10 on which the cargo is placed. The cargo handling device 13 is installed on the straddle leg 12. The cargo handling device 13 has a mast 131 and forks 132.

[0022] The mast 131 extends vertically in the vertical direction Dv from the straddle leg 12 and is also mounted on the straddle leg 12 so as to be movable in the direction of travel Ds. For the sake of explanation, the lower side (the direction in which gravity acts) in the vertical direction Dv will be simply referred to as "lower side Dvd," and the opposite side (upper side) will be simply referred to as "upper side Dvu."

[0023] The mast 131 is mounted so as to span both the right straddle leg 121 and the left straddle leg 122, and extends upward Dvu from each of the right and left straddle legs 121 and 122, respectively. When driven, the mast 131 moves back and forth in the direction of travel Ds along the direction in which the right and left straddle legs 121 and 122 extend. Specifically, for example, the entire mast 131 is moved in the direction of travel Ds when a reach mechanism (not shown) provided on the mast 131 is driven.

[0024] Furthermore, the mast 131 can be tilted forward on the straddle legs 12 by being driven. Specifically, for example, the entire mast 131 tilts forward on the straddle legs 12 by being driven by a tilt mechanism (not shown) provided on the mast 131. Here, "tilting forward on the straddle legs" means that the mast 131 is tilted such that the end of the upper Dvu on the mast 131 is positioned further forward on the straddle legs than the end of the lower Dvd on the mast 131.

[0025] The forks 132 are mounted in pairs on the mast 131, extending from the mast 131 to the rear side Dsb. The pair of forks 132 are spaced apart from each other in the vehicle width direction Dw. The pair of forks 132 are mounted on the mast 131 so as to be movable in the vertical direction Dv. The pair of forks 132 move up and down in the vertical direction Dv along the mast 131 when the mast 131 is driven. Specifically, for example, the entire fork 132 moves in the vertical direction Dv when a lift mechanism (not shown) provided on the mast 131 is driven.

[0026] Therefore, as the mast 131 moves vertically Dv on the straddle leg 12 and also moves to the rear Dsb, the fork 132 is inserted into, for example, the fork pocket of a pallet on which a load is placed. By being inserted into this fork pocket, the fork 132 can lift the load placed on the pallet together with the pallet.

[0027] For the sake of explanation, both the pallet and the cargo placed on it will be collectively referred to as "cargo Lg" (see Figure 3). Furthermore, the fork 132 is tilted relative to the horizontal plane along with the cargo Lg when the cargo Lg is placed on it, as the mast 131 is tilted forward Dsf on the straddle leg 12.

[0028] Hereinafter, the movement of the mast 131 in the direction of travel Ds along with the fork 132 when the mast 131 is driven will be referred to as "reaching motion". Furthermore, within this reaching motion, the movement of the mast 131 to the rear side Dsb will be referred to as "reaching out", and the movement of the mast 131 to the front side Dsf will be referred to as "reaching in".

[0029] Furthermore, the movement of the forks 132 up and down in the vertical direction Dv due to the driving of the mast 131 is referred to as "lift operation." Within this lift operation, the movement of the forks 132 upwards to Dvu is referred to as "lift up," and the movement of the forks 132 downwards to Dvd is referred to as "lift down."

[0030] Furthermore, the movement in which the forks 132 tilt relative to the horizontal plane when the mast 131 is driven is called "tilt movement." Of this tilt movement, the tilt of the forks 132 toward the front side Dsf relative to the horizontal plane is called "tilt up," and the return of the forks 132 from the state of being tilted toward the front side Dsf to their original position is called "tilt down." Here, "tilting toward the front side Dsf relative to the horizontal plane" means that the forks 132 tilt so that the end of the rear side Dsb of the pair of forks 132 is positioned above the end of the front side Dsf of the pair of forks 132.

[0031] Furthermore, the mast 131 transmits to the travel control device 20 the lifting height, which indicates the position of the fork 132 in the vertical direction Dv, and the reach length, which indicates the amount of protrusion of the fork 132 in the direction of travel Ds. The lifting height, which indicates the position of the fork 132 in the vertical direction Dv, means the height in the vertical direction Dv from the position when the fork 132 is positioned at its lowest point Dvd. The amount of protrusion of the fork 132 in the direction of travel Ds means the amount of protrusion in the direction of travel Ds from the position when the fork 132 is positioned at its furthest forward point Dsf.

[0032] (Traction mechanism) The running mechanism 14 supports the vehicle 11 and the straddle legs 12 from the lower side Dvd in the vertical direction Dv, and makes them movable on the road surface R. As shown in Figures 2 and 3, the running mechanism 14 in this embodiment has a drive wheel 141, a first driven wheel 142, and a second driven wheel 143.

[0033] The drive wheel 141 is provided on the vehicle 11. As shown in Figure 3, the drive wheel 141 has a drive wheel body 141a that can rotate while in contact with the road surface R, a drive motor 141b that rotates the drive wheel body 141a while it is in contact with the road surface R, and a steering motor 141c that can change the direction of the drive wheel body 141a. These drive motor 141b and steering motor 141c are connected to the drive wheel body 141a, for example.

[0034] The drive motor 141b rotates based on a signal indicating a drive instruction transmitted from the travel control device 20. Specifically, the drive motor 141b receives a signal indicating torque (rotational speed) from the travel control device 20 and rotates the drive wheel body 141a by rotating based on this torque. The steering motor 141c is rotatable around a first pivot axis O1 that extends in the vertical direction Dv. In this embodiment, the first pivot axis O1 extends in the vertical direction Dv so as to pass through the center of the drive wheel 141. The steering motor 141c steers the drive wheel body 141a based on a signal indicating a steering instruction transmitted from the travel control device 20.

[0035] Specifically, the steering motor 141c receives a signal indicating the rotation angle from the travel control device 20 and adjusts its own posture to this rotation angle. In other words, the rotation of the steering motor 141c adjusts the inclination of the drive wheel body 141a with respect to the direction of travel Ds, resulting in a change in the direction of the drive wheel body 141a.

[0036] The first driven wheel 142 is located at the rear end Dsb of the left straddle leg 122. The first driven wheel 142 includes, for example, a first driven wheel body 142a that can rotate while in contact with the road surface R, and a steering motor 142b that can change the orientation of the first driven wheel body 142a. The steering motor 142b is connected to, for example, the first driven wheel body 142a. The steering motor 142b is rotatable about a second pivot axis O2 that extends in the vertical direction Dv. In this embodiment, the second pivot axis O2 extends in the vertical direction Dv so as to pass through the center of the first driven wheel 142. The steering motor 142b steers the first driven wheel body 142a based on a signal indicating a steering instruction transmitted from, for example, the travel control device 20.

[0037] Specifically, the steering motor 142b receives a signal indicating the rotation angle from the travel control device 20 and adjusts its own posture to this rotation angle. In other words, the rotation of the steering motor 142b adjusts the inclination of the first driven wheel body 142a with respect to the direction of travel Ds, resulting in a change in the orientation of the first driven wheel body 142a.

[0038] The second driven wheel 143 is located at the rear end Dsb of the right straddle leg 121. The second driven wheel 143 includes, for example, a second driven wheel body 143a that can rotate while in contact with the road surface R, and a steering motor 143b that can change the orientation of the second driven wheel body 143a. The steering motor 143b is connected to, for example, the second driven wheel body 143a. The steering motor 143b is rotatable about a third pivot axis O3 that extends in the vertical direction Dv. In this embodiment, the third pivot axis O3 extends in the vertical direction Dv so as to pass through the center of the second driven wheel 143. The steering motor 143b steers the second driven wheel body 143a based on a signal indicating a steering instruction transmitted from, for example, the travel control device 20.

[0039] Specifically, the steering motor 143b receives a signal indicating the rotation angle from the travel control device 20 and adjusts its own posture to this rotation angle. In other words, the rotation of the steering motor 143b adjusts the inclination of the second driven wheel body 143a with respect to the direction of travel Ds, resulting in a change in the orientation of the second driven wheel body 143a.

[0040] In this embodiment, a virtual triangle is formed when viewed from the vertical direction Dv by a first virtual line V1 connecting the first rotation axis O1 and the second rotation axis O2, a second virtual line V2 connecting the first rotation axis O1 and the third rotation axis O3, and a third virtual line V3 connecting the second rotation axis O2 and the third rotation axis O3. This triangle is, for example, an isosceles triangle in which the lengths of the first virtual line V1 and the second virtual line V2 are equal when viewed from the vertical direction Dv.

[0041] In other words, the distance between the first rotation axis O1 and the second rotation axis O2 (length of the first virtual line V1) in a two-dimensional plane coordinate system consisting of the passage extension direction D1 and the passage width direction D2 is equal to the distance between the first rotation axis O1 and the third rotation axis O3 (length of the second virtual line V2). In this embodiment, the distance between the second rotation axis O2 and the third rotation axis O3 (length of the third virtual line V3) is shorter than the length of the first virtual line V1 and the length of the second virtual line V2.

[0042] (Weight sensor) The weight sensor 15 is a sensor that detects the weight of a load Lg when it is placed on the fork 132. In this embodiment, the weight sensor 15 is a load cell. The weight sensor 15 acquires weight data when a load is applied to it. The weight sensor 15 transmits a signal indicating the acquired weight data to the travel control device 20.

[0043] As shown in Figures 2 and 3, multiple weight sensors 15 are provided on the forks 132. Specifically, two weight sensors 15 are located on the fork 132 on one side Dwr of the pair of forks 132, and two weight sensors 15 are located on the fork 132 on the other side Dwl.

[0044] These weight sensors 15, provided on each fork 132, are positioned spaced apart from each other in the direction of travel Ds on each fork 132. The positions of the two weight sensors 15 provided on the fork 132 located on one side Dwr are aligned in the direction of travel Ds with the positions of the two weight sensors 15 provided on the fork 132 located on the other side Dwl.

[0045] (Self-positioning sensor) In this embodiment, the self-position sensor 16 detects the position and orientation of an object by irradiating the surroundings with laser light and detecting (receiving) reflected light from surrounding objects. The self-position sensor 16 is, for example, a laser scanner such as a 2D-LiDAR (Light Detection And Ranging) that scans laser light in the horizontal direction. The self-position sensor 16 is provided, for example, on a surface of the vehicle 11 facing upward Dvu.

[0046] The self-position sensor 16 detects the contours of a pair of walls W and the contour of the forklift 10 by scanning a laser beam horizontally when the forklift 10 is traveling in a passageway. Specifically, the self-position sensor 16 acquires data showing the contours of the walls W and the contour of the forklift 10 through multiple plots. Each plot of data showing the contours of the walls W and the forklift 10 is associated with coordinates in a two-dimensional planar coordinate system, for example. The self-position sensor 16 transmits a signal indicating the acquired data to the travel control device 20.

[0047] (Driving control device) The travel control device 20 controls the travel mechanism 14 of the forklift 10 as it travels toward a target position P within the logistics facility LF, thereby controlling the speed of the moving object (acceleration in the direction of travel Ds of the forklift 10). The travel control device 20 is installed, for example, inside the vehicle 11 of the forklift 10.

[0048] The "target position P" referred to here can be, for example, multiple points located along a pre-instructed travel route for the forklift 10, or a position in a passageway where the forklift 10 can perform loading or unloading operations such as loading or unloading cargo Lg. The target position P is pre-set by, for example, a higher-level device 40. The travel control device 20 receives a signal from the higher-level device 40 indicating the location of this target position P.

[0049] As shown in Figure 4, the driving control device 20 in this embodiment includes a cargo handling device drive unit 21, a cargo information acquisition unit 22, a vehicle information acquisition unit 23, a correspondence relationship information acquisition unit 24, a cargo handling device information acquisition unit 25, an allowable acceleration acquisition unit 26, an acceleration determination unit 27, a target reach length acquisition unit 28, a reach length determination unit 29, a self-position acquisition unit 30, a self-position determination unit 31, a drive wheel control unit 32, and a storage unit 33.

[0050] (Cargo handling equipment drive unit) The cargo handling device drive unit 21 drives the mast 131 of the cargo handling device 13, thereby causing the cargo handling device 13 to perform the reach, lift, and tilt operations described above. In this embodiment, the cargo handling device drive unit 21 drives the mast 131 of the cargo handling device 13 based on signals received from the outside indicating the lifting height of the forks 132, the reach length of the forks 132, and instructions for tilt operation. The cargo handling device drive unit 21 includes a lifting control unit 211, a forward / backward control unit 212, and a tilting control unit 213.

[0051] The lifting control unit 211 transmits a signal to the mast 131 indicating a lift operation based on the lifting height of the fork 132 received from the outside. In this embodiment, the lifting control unit 211 has a lift-down instruction unit 211a and a lift-up instruction unit 211b.

[0052] The lift-down instruction unit 211a transmits a signal to the mast 131 indicating that the fork 132 should be lowered (moved to the lower side DVD) until it reaches the accepted lifting height. When the mast 131 receives the signal from the lift-down instruction unit 211a, it moves the fork 132 to the lower side DVD. After the mast 131 has moved the fork 132 to the lifting height, the lift-down instruction unit 211a transmits a signal to the drive wheel control unit 32 indicating that the lift-down is complete.

[0053] The lift-up instruction unit 211b sends a signal to the mast 131 indicating that the forks 132 should be raised (moved to the upper Dvu) until the accepted lifting height is reached. When the mast 131 receives the signal from the lift-up instruction unit 211b, it moves the forks 132 to the upper Dvu. After the mast 131 has moved the forks 132 to the lifting height, the lift-up instruction unit 211b sends a signal to the drive wheel control unit 32 indicating that the lift-up is complete.

[0054] The forward / backward control unit 212 transmits a signal to the mast 131 indicating a reach operation based on the reach length of the fork 132 received from the outside. In this embodiment, the forward / backward control unit 212 has a reach-out instruction unit 212a and a reach-in instruction unit 212b.

[0055] The reach-out instruction unit 212a sends a signal to the mast 131 indicating that the forks 132 should be extended (moved to the rear Dsb of the mast 131) until the received reach length is reached. When the mast 131 receives the signal from the reach-out instruction unit 212a, it moves the forks 132 to the rear Dsb. After the mast 131 has moved the forks 132 to the reach length, the reach-out instruction unit 212a sends a signal to the drive wheel control unit 32 indicating that the reach-out is complete.

[0056] The reach-in instruction unit 212b sends a signal to the mast 131 indicating that the fork 132 should be retracted (moved to the front Dsf of the mast 131) until it reaches the received reach length. When the mast 131 receives the signal from the reach-in instruction unit 212b, it moves the fork 132 to the front Dsf. After the mast 131 has moved the fork 132 to the reach length, the reach-in instruction unit 212b sends a signal to the drive wheel control unit 32 indicating that the reach-in is complete.

[0057] The tilt control unit 213 transmits a signal to the mast 131 indicating an instruction for tilt operation. In this embodiment, the tilt control unit 213 has a tilt-up instruction unit 213a and a tilt-down instruction unit 213b.

[0058] The tilt-up instruction unit 213a transmits a signal to the mast 131 indicating an instruction to tilt the mast 131 by a predetermined angle (tilting the mast 131 toward the forward side Dsf). When the mast 131 receives the signal from the tilt-up instruction unit 213a, it tilts the forks 132 toward the forward side Dsf with respect to the horizontal plane. After the mast 131 has tilted, the tilt-up instruction unit 213a sends a signal to the cargo information acquisition unit 22 indicating that the tilt-up is complete.

[0059] The tilt-down instruction unit 213b transmits a signal to the mast 131 indicating an instruction to return the tilt to its original position. When the mast 131 receives the signal from the tilt-down instruction unit 213b, it returns the forks 132 to their original position parallel to the horizontal plane. After the tilt of the mast 131 has been returned to its original position, the tilt-down instruction unit 213b transmits a signal to the cargo information acquisition unit 22 indicating that the tilt-down is complete.

[0060] (Package Information Acquisition Unit) The cargo information acquisition unit 22 acquires cargo information when the cargo handling device drive unit 21 is driven and cargo Lg is placed on the fork 132. In this embodiment, the cargo information includes the weight of cargo Lg and the center of gravity position CG1 of cargo Lg (see Figure 3(a)). The cargo information acquisition unit 22 includes a cargo load acquisition unit 221, a cargo weight calculation unit 222, and a cargo center of gravity position detection unit 223.

[0061] The load acquisition unit 221 acquires the load acting on the fork 132 from the load Lg placed on the fork 132. In this embodiment, the load acquisition unit 221 receives weight data transmitted from each weight sensor 15 provided on the fork 132. The load acquisition unit 221 sends signals indicating the weight acquired by each weight sensor 15 to the load weight calculation unit 222 and the load center of gravity position detection unit 223.

[0062] The load weight calculation unit 222 obtains the weight of the load Lg by summing up the weight data received from the load weight acquisition unit 221. In other words, in this embodiment, the load weight calculation unit 222 obtains the weight of the load Lg based on the weight data acquired by the four weight sensors 15 provided on the fork 132. The load weight calculation unit 222 sends a signal indicating the acquired weight of the load Lg to the vehicle information acquisition unit 23.

[0063] The load center of gravity detection unit 223 detects the center of gravity position CG1 of the load Lg placed on the fork 132. An example of the center of gravity position CG1 of the load Lg in the direction of travel Ds is shown in Figure 3. The load center of gravity detection unit 223 detects the center of gravity position CG1 of the load Lg based on the weight data received from the load load acquisition unit 221.

[0064] Specifically, the cargo center of gravity position detection unit 223 detects the center of gravity position CG1 of the cargo Lg in the vehicle width direction Dw based on, for example, the load difference of a pair of forks 132. Also, when, for example, the cargo center of gravity position detection unit 223 receives a signal from the tilt-up instruction unit 213a in the cargo handling device drive unit 21 indicating that tilt-up is complete, it detects the center of gravity position CG1 of the cargo Lg in the direction of travel Ds based on the change in load before and after tilt-up measured by two weight sensors 15 provided on each fork 132. The cargo center of gravity position detection unit 223 sends a signal indicating the detected center of gravity position CG1 to the vehicle information acquisition unit 23.

[0065] (Vehicle Information Acquisition Unit) The vehicle information acquisition unit 23 acquires vehicle information when the cargo handling device drive unit 21 is driven and the load Lg is placed on the forks 132. In this embodiment, the vehicle information includes the weight of the forklift 10 including the load Lg and the center of gravity position CG of the forklift 10 including the load Lg. The vehicle information acquisition unit 23 has a weight calculation unit 231 and a center of gravity position detection unit 232.

[0066] The weight calculation unit 231 obtains the total weight of the forklift 10, including the load Lg, by adding the weight of the load Lg received from the load weight calculation unit 222 of the load information acquisition unit 22 and the weight of the forklift 10 that has been previously stored in the storage unit 33.

[0067] The center of gravity detection unit 232 detects the overall center of gravity CG of the forklift 10, including the load Lg. Based on the center of gravity CG1 of the load Lg received from the load center of gravity detection unit 223 of the load information acquisition unit 22, and the center of gravity CG2 of the forklift 10 which is stored in advance by the storage unit 33, the center of gravity detection unit 232 detects the overall center of gravity CG of the forklift 10, including the load Lg.

[0068] Specifically, the center of gravity detection unit 232 acquires the center of gravity position CG in coordinates of a three-dimensional coordinate system defined by the vehicle width direction Dw (X direction), the direction of travel Ds (Y direction), and the vertical direction Dv (Z direction). The origin of this three-dimensional coordinate system is set, for example, at a predetermined position within the vehicle 11. The center of gravity detection unit 232 sends a signal indicating the acquired center of gravity position CG to the correspondence relationship information acquisition unit 24.

[0069] (Relationship information acquisition unit) The correspondence relationship information acquisition unit 24 acquires correspondence relationship information based on the center of gravity position CG detected by the center of gravity position detection unit 232 of the vehicle information acquisition unit 23. In the correspondence relationship information in this embodiment, the lifting height of the fork 132, the reach length of the fork 132, and the acceleration that positions the zero moment point Zmp within the stable region R1 are related to each other.

[0070] Here, when the forklift 10 accelerates while in motion, the resultant force vector F+G, which is the vector F representing the direction and magnitude of the inertial force acting in the opposite direction to the direction of acceleration, and the vector G representing the direction and magnitude of gravity acting on the downward side Dvd, is conceptually shown in Figure 3.

[0071] In the correspondence information, the Zero Moment Point (Zmp) refers to the intersection point between the virtual extension of the resultant force vector F+G and the road surface R. Figure 3 shows an example where the direction of travel Ds of the forklift 10 coincides with the direction of passage extension D1, and the forklift 10 is traveling while accelerating towards the front side Dsf.

[0072] Furthermore, as shown in Figure 5, the stable region R1 refers to the triangular region defined when a virtual triangle formed by the first virtual line V1, the second virtual line V2, and the third virtual line V3 is projected onto the road surface R when viewed from the upper side Dvu.

[0073] Therefore, the stable region R1 in this embodiment is the region formed by connecting the first rotation axis O1, the second rotation axis O2, and the third rotation axis O3 with straight lines (shown as dashed lines in Figure 5) on the road surface R. In other words, the stable region R1 in this embodiment is arranged such that the vertices of a triangle formed by the intersection of two sides of the same length face the front side Dsf.

[0074] Furthermore, in this embodiment, an allowable region R2, which is triangular in shape (isosceles triangle) and similar to the stable region R1, is arranged within the stable region R1. The area of ​​the allowable region R2 is smaller than the area of ​​the stable region R1, and the vertices of the triangle formed by the intersection of two sides of equal length are positioned to face the front side Dsf.

[0075] For the sake of explanation, in the following, we will refer to the vertex of the triangle formed by two sides of equal length intersecting in the stable region R1 as "A1," and the vertex of the triangle formed by two sides of equal length intersecting in the allowable region R2 as "A2." Furthermore, we will refer to the vertices of the triangles other than vertex A2 in the allowable region R2 as "A3."

[0076] The correspondence information acquired by the correspondence information acquisition unit 24 in this embodiment is represented, for example, by the following formulas (i) and (ii). α≧(L1-Yg-R·Kr) / (Zg+L·Kr) ···(i) α≦(L2-Yg-R Kr) / (Zg+L Kr) ···(ii)

[0077] Here, α in equations (i) and (ii) is the allowable acceleration that positions the zero-moment point Zmp within the stable region R1, and is treated as a variable during the operation of the travel control device 20. The unit of the allowable acceleration α is G, and it is the value obtained by dividing the acceleration by the acceleration due to gravity.

[0078] In equation (i), L1 is the distance in the direction of travel Ds from vertex A1 of the stable region R1 to vertex A2 of the allowable region R2, and in equation (ii), L2 is the distance in the direction of travel Ds from vertex A1 of the stable region R1 to vertex A3 of the allowable region R2.

[0079] These L1 and L2 are constants that are set in advance, for example, during the design phase of the forklift 10. These L1 and L2 are stored in advance, for example, by the storage unit 33. In other words, L1 and L2 are acquired by the correspondence relationship information acquisition unit 24 by the correspondence relationship information acquisition unit 24 referring to the storage unit 33.

[0080] Furthermore, Yg in equations (i) and (ii) is the coordinate of the center of gravity position CG of the forklift 10, including the load Lg, in the direction of travel Ds (Y direction) when the forks 132 are positioned at their lowest Dv and forward Dsf. Zg in equations (i) and (ii) is the coordinate of the center of gravity position CG of the forklift 10, including the load Lg, in the vertical direction Dv (Z direction) when the forks 132 are positioned at their lowest Dv and forward Dsf. In other words, these Yg and Zg are coordinates received by the correspondence relationship information acquisition unit 24 from the center of gravity position detection unit 232 of the vehicle information acquisition unit 23.

[0081] Furthermore, in equations (i) and (ii), R is the reach length, which indicates the amount of fork 132 protruding in the direction of travel Ds, and L is the lifting height, which indicates the position (height) of fork 132 in the vertical direction Dv. These R and L are treated as variables during the operation of the travel control device 20.

[0082] Furthermore, Kr in equations (i) and (ii) is a value determined by the weight of the package Lg (reach-mass ratio), and can be expressed, for example, by the following equation. Kr = Mr / M ... (iii)

[0083] Mr is the weight of the cargo handling device 13, which is stored in the memory unit 33, plus the weight of the cargo Lg obtained by the cargo weight calculation unit 222. M is the weight of the forklift 10, which is stored in the memory unit 33, plus the weight of the cargo Lg obtained by the cargo weight calculation unit 222. In other words, M is the total weight of the forklift 10, including the cargo Lg.

[0084] The correspondence relationship information acquisition unit 24 sends a signal indicating the acquired correspondence relationship information to the allowable acceleration acquisition unit 26 and the target reach length acquisition unit 28.

[0085] (Cargo handling equipment information acquisition unit) In this embodiment, the cargo handling equipment information acquisition unit 25 acquires the lifting height and reach length of the forks 132 transmitted from the mast 131 while the forklift 10 is in motion. The cargo handling equipment information acquisition unit 25 sends signals indicating the acquired lifting height and reach length of the forks 132 to the allowable acceleration acquisition unit 26. The cargo handling equipment information acquisition unit 25 also sends a signal indicating the acquired lifting height of the forks 132 to the target reach length acquisition unit 28.

[0086] (Allowable acceleration acquisition unit) The permissible acceleration acquisition unit 26 acquires the permissible acceleration from the correspondence relationship information acquired by the correspondence relationship information acquisition unit 24, based on the lifting height and reach length of the fork 132 acquired by the cargo handling equipment information acquisition unit 25.

[0087] Specifically, the allowable acceleration acquisition unit 26 calculates the allowable acceleration as acceleration by substituting the lifting height and reach length of the fork 132, which are received from the cargo handling equipment information acquisition unit 25, into the correspondence relationship information represented by the above formulas (i) and (ii) received from the correspondence relationship information acquisition unit 24.

[0088] Specifically, the allowable acceleration acquisition unit 26 calculates the allowable acceleration α using the following equation (iv), which shows the case where equation (i) above is equal when the acceleration of the moving forklift 10 is applied to the rear side Dsb. α=(L1-Yg-R Kr) / (Zg+L Kr) ···(iv)

[0089] Furthermore, the allowable acceleration acquisition unit 26 calculates the allowable acceleration α using the following equation (v), which shows the case where equation (ii) above is equal when the acceleration of the moving forklift 10 is applied to the front side Dsf. α=(L2-Yg-R Kr) / (Zg+L Kr) ···(v)

[0090] The allowable acceleration acquisition unit 26 sends a signal indicating the calculated allowable acceleration to the acceleration determination unit 27, the target reach length acquisition unit 28, and the self-position determination unit 31, respectively.

[0091] (Acceleration judgment section) The acceleration determination unit 27 determines (compares) whether the magnitude of the allowable acceleration received from the allowable acceleration acquisition unit 26 is smaller than the magnitude of the maximum acceleration of the forklift 10. Here, "magnitude of the maximum acceleration of the forklift 10" means, for example, the magnitude of the acceleration acting on the forklift 10 when the drive motor 141b rotates with the maximum torque that the drive wheels 141 can generate, with no load Lg placed on the forks 132. The maximum acceleration is a constant (in units of G). The maximum acceleration is stored in advance, for example, by the storage unit 33. In other words, the maximum acceleration is obtained by the acceleration determination unit 27 referring to the storage unit 33.

[0092] The acceleration determination unit 27 determines that "the allowable acceleration is less than the maximum acceleration" if the magnitude of the allowable acceleration is less than the magnitude of the maximum acceleration. On the other hand, the acceleration determination unit 27 determines that "the allowable acceleration is greater than or equal to the maximum acceleration" if the magnitude of the allowable acceleration is greater than or equal to the magnitude of the maximum acceleration. The acceleration determination unit 27 sends a signal indicating the determination result to the target reach length acquisition unit 28 and the drive wheel control unit 32.

[0093] (Target reach length acquisition section) If the determination result received from the acceleration determination unit 27 indicates that "the allowable acceleration is less than the maximum acceleration", the target reach length acquisition unit 28 acquires the reach length of the fork 132 corresponding to the allowable acceleration received from the allowable acceleration acquisition unit 26 from the correspondence information acquired by the correspondence information.

[0094] Specifically, the target reach length acquisition unit 28 calculates the target reach length by substituting the lifting height of the fork 132 received from the cargo handling equipment information acquisition unit 25 and the acceleration received from the allowable acceleration acquisition unit 26 into the correspondence information represented by the above formulas (i) and (ii) received from the correspondence information acquisition unit 24.

[0095] The target reach length acquisition unit 28 calculates the target reach length R using the following equation (vi), which is obtained by rearranging equation (iv) above, when the acceleration of the moving forklift 10 is applied to the rear side Dsb. R=(L1-Yg-α·(Zg+L·Kr)) / Kr···(vi)

[0096] Furthermore, when the acceleration of the moving forklift 10 is applied to the rear side Dsb, the target reach length acquisition unit 28 calculates the target reach length R using the following equation (vii), which is obtained by rearranging equation (v) above. R=(L2-Yg-α·(Zg+L·Kr)) / Kr···(vii)

[0097] The target reach length acquisition unit 28 sends a signal indicating the calculated target reach length to the cargo handling device drive unit 21.

[0098] (Reach length determination unit) The reach length determination unit 29 determines whether the reach length of the fork 132, as received from the cargo handling equipment information acquisition unit 25, has reached the target reach length, as received from the target reach length acquisition unit 28. Specifically, the reach length determination unit 29 determines whether the reach length of the fork 132 falls within a range obtained by adding or subtracting a predetermined threshold value from the target reach length. This predetermined threshold value is stored in advance, for example, by the storage unit 33.

[0099] The reach length determination unit 29 determines that the target reach length has been reached if the reach length falls within this range. On the other hand, the reach length determination unit 29 determines that the target reach length has not been reached if the reach length does not fall within this range. The reach amount determination unit sends a signal indicating the determination result to the cargo information acquisition unit 22 and the cargo handling equipment information acquisition unit 25.

[0100] (Self-location acquisition unit) The self-position acquisition unit 30 acquires the position of the forklift 10 based on the data received from the self-position sensor 16. Specifically, the self-position acquisition unit 30 acquires data indicating the location on the travel path where the position of the forklift 10 indicated by the data received from the self-position sensor 16 corresponds, by referring to the travel path data stored in advance by the storage unit 33. This data is represented, for example, in coordinates in a two-dimensional plane coordinate system. The self-position acquisition unit 30 sends a signal indicating the acquired data to the self-position determination unit 31.

[0101] (Self-position determination unit) The self-position determination unit 31 determines whether the forklift 10 has reached the target position P based on the data received from the self-position acquisition unit 30. Specifically, the self-position determination unit 31 determines whether the position (coordinates) of the forklift 10 indicated by the data received from the self-position acquisition unit 30 is located within a predetermined threshold range relative to the coordinates of the target position P, which are stored in advance by the storage unit 33. The threshold range can be represented, for example, by a circle with its center at the target position P and a radius of a distance on the order of millimeters (mm).

[0102] Therefore, the self-position determination unit 31 determines that the forklift 10 has reached the target position if its position is within a predetermined threshold range relative to the target position P. On the other hand, the self-position determination unit 31 determines that the forklift 10 has not reached the target position if its position is outside the predetermined threshold range relative to the target position P. This threshold range is stored in advance, for example, by the storage unit 33. The self-position determination unit 31 sends a signal indicating this determination result to the cargo handling equipment information acquisition unit 25.

[0103] Here, the cargo handling equipment information acquisition unit 25 receives this determination result from the self-position determination unit 31, and if the determination result indicates that the target position has been reached, it acquires the lifting height and reach length of the forks 132 transmitted from the mast 131.

[0104] Furthermore, the self-position determination unit 31 determines whether the stopping position of the forklift 10 is in front of the target position P, based on the allowable acceleration received from the allowable acceleration acquisition unit 26. Here, "stopping position" means the position where the forklift 10 can stop if it continues to travel with the allowable acceleration applied to the rear side Dsb from the position of the forklift 10 obtained from the self-position acquisition unit 30. Here, "in front" means on the side of the forklift 10 that is closer to the target position P. The self-position determination unit 31 calculates the geometric distance in a two-dimensional plane coordinate system based, for example, the coordinates of the self-position obtained from the self-position acquisition unit 30 and the coordinates of the target position P.

[0105] Therefore, the self-position determination unit 31 determines that "the stopping position is in front of the target position P" if the stopping position is in front of the target position P. On the other hand, the self-position determination unit 31 determines that "the stopping position is not in front of the target position P" if the stopping position is not in front of the target position P. The self-position determination unit 31 sends a signal indicating this determination result to the drive wheel control unit 32.

[0106] (Drive wheel control unit) When the drive wheel control unit 32 receives a signal from the forward / backward control unit 212 indicating that reach-out is complete or reach-in is complete, and the determination result received from the self-position determination unit 31 indicates that "the stopping position is close", it acquires multiple torques and drives the drive wheel 141 using one of the acquired torques. In this embodiment, the drive wheel control unit 32 includes a torque acquisition unit 321, a torque determination unit 322, and a drive wheel drive unit 323.

[0107] The torque acquisition unit 321 acquires acceleration torque when the determination result received from the self-position determination unit 31 indicates that "the stopping position is close ahead." Here, "acceleration torque" refers to, for example, the torque required to rotate the drive wheels 141 so that the forklift 10 is subjected to an allowable acceleration toward the forward side Dsf. The torque acquisition unit 321 sends a signal indicating the acquired acceleration torque to the torque determination unit 322.

[0108] Furthermore, the torque acquisition unit 321 acquires deceleration torque if the determination result received from the self-position determination unit 31 indicates that "the stopping position is not close." Here, "deceleration torque" refers to, for example, the torque required to rotate the drive wheels 141 so that an allowable acceleration is applied to the rear side Dsb of the forklift 10. The torque acquisition unit 321 sends a signal indicating the acquired deceleration torque to the torque determination unit 322.

[0109] Furthermore, the torque acquisition unit 321 acquires an upper limit torque when it acquires acceleration torque or deceleration torque, or when the acceleration determination unit 27 indicates that "the allowable acceleration is equal to or greater than the maximum acceleration." Here, "upper limit torque" refers to the maximum torque that the drive wheels 141 can generate. The torque acquisition unit 321 sends a signal indicating the acquired upper limit torque to the torque determination unit 322.

[0110] Furthermore, when the upper limit torque is acquired, the torque acquisition unit 321 acquires the indicative torque. Here, "indicative torque" refers to the torque determined by the PID control unit (not shown) of the travel control device 20, which can acquire the difference between the position of the forklift 10 and the target position P, as well as the derivative of this difference. Therefore, the torque acquisition unit 321 acquires the indicative torque from this PID control unit. The torque acquisition unit 321 sends a signal indicating the acquired indicative torque to the torque determination unit 322.

[0111] The torque determination unit 322 determines the torque to be used to drive the drive wheels 141 from the torques acquired by the torque acquisition unit 321. Specifically, the torque determination unit 322 determines the smallest of the acceleration torque or deceleration torque, the upper limit torque, and the instructed torque as the torque to be used to drive the drive wheels 141. The torque determination unit 322 sends a signal indicating the determined torque to be used for driving to the drive wheel drive unit 323.

[0112] The drive wheel drive unit 323 rotates the drive wheel 141 using the torque received from the torque determination unit 322. Specifically, the drive wheel drive unit 323 drives the drive wheel 141 by transmitting a signal indicating the torque received from the torque determination unit 322 to the drive motor 141b of the drive wheel 141.

[0113] (Operation of the driving control system) Next, an example of the operation of the travel control device 20 in this embodiment will be described with reference to Figure 6.

[0114] When the forklift 10 performs cargo handling operations at a target position P where cargo handling operations can be performed, the cargo handling device drive unit 21 drives the cargo handling device 13 (step S1). The cargo handling device drive unit 21 causes the cargo handling device 13 to sequentially perform lift operations (lift down or lift up), reach operations (reach out), lift operations (lift up), reach operations (reach in), lift operations (lift down), tilt operations (tilt up and tilt down). In this case, during reach-in, the mast 131 is driven in the direction of travel Ds so that the forks 132 are positioned at the furthest forward Dsf. During lift-down, the mast 131 is driven in the vertical direction Dv so that the forks 132 are positioned at the lowest Dvd.

[0115] When the cargo handling device drive unit 21 drives the cargo handling device 13 and the cargo Lg is placed on the forks 132, the cargo information acquisition unit 22 acquires cargo information (step S2). Specifically, before the mast 131 is tilted up, the center of gravity position detection unit 232 of the cargo information acquisition unit 22 detects the center of gravity position CG1 of the cargo Lg in the vehicle width direction Dw, and when the mast 131 is tilted up, the center of gravity position detection unit 232 detects the center of gravity position CG1 of the cargo Lg in the direction of travel Ds.

[0116] Next, the vehicle information acquisition unit 23 acquires the weight of the forklift 10, including the load Lg, and the center of gravity position CG as vehicle information (step S3). Then, the correspondence relationship information acquisition unit 24 acquires correspondence relationship information (step S4).

[0117] The processes described above, from step S1 to step S4, are repeatedly executed while the forklift 10 is in operation (while the movement control system 1 is running).

[0118] Next, an example of the operation of the driving control device 20 after the correspondence information has been acquired will be explained with reference to Figure 7.

[0119] First, the drive wheel drive unit 323 of the drive wheel control unit 32 drives the drive wheels 141 to move the forklift 10 along the travel path (step S10). The cargo handling equipment information acquisition unit 25 acquires the lifting height and reach length of the forks 132 while the forklift 10 is traveling (step S11).

[0120] Next, the permissible acceleration acquisition unit 26 acquires the permissible acceleration from the correspondence relationship information acquired by the correspondence relationship information acquisition unit 24, based on the lifting height and reach length of the fork 132 acquired by the cargo handling equipment information acquisition unit 25 (step S12).

[0121] Next, the acceleration determination unit 27 determines whether the magnitude of the allowable acceleration obtained by the allowable acceleration acquisition unit 26 is less than the magnitude of the maximum acceleration of the forklift 10 (step S13). If the acceleration determination unit 27 determines that "the allowable acceleration is greater than or equal to the maximum acceleration" (step S13: NO), the torque acquisition unit 321 of the drive wheel control unit 32 acquires the upper limit torque (step S14). On the other hand, if the acceleration determination unit 27 determines that "the allowable acceleration is less than the maximum acceleration" (step S13: YES), the target reach length acquisition unit 28 acquires the target reach length of the fork 132 corresponding to the acquired allowable acceleration from the correspondence information (step S18).

[0122] Following the processing in step S18, the cargo handling control step S20 is executed. As shown in Figure 8, in the cargo handling control step S20, first, the cargo handling device drive unit 21 receives the target reach length from the target reach length acquisition unit 28 (step S21). Next, the forward / backward control unit 212 of the cargo handling device drive unit 21 drives the mast 131 of the cargo handling device 13 by transmitting a signal indicating an instruction for reach operation based on the target reach length to the mast 131 (step S22).

[0123] Next, the reach length determination unit 29 determines whether the reach length of the fork 132 has reached the target reach length (step S23). If the reach length determination unit 29 determines that the target reach length has been reached (step S23: YES), the cargo handling control step S20 is terminated. After the cargo handling control step S20 is terminated, step S14 described above is executed. On the other hand, if the reach length determination unit 29 determines that the target reach length has not been reached (step S23: NO), the process returns to step S22.

[0124] Returning to Figure 7, following the processing in step S14, the torque acquisition unit 321 acquires the instructed torque (step S15). Next, the torque determination unit 322 of the drive wheel control unit 32 determines the drive torque (step S16). Then, the drive wheel drive unit 323 of the drive wheel control unit 32 drives the drive wheels 141 with the drive torque determined by the torque determination unit 322 (step S17).

[0125] The processes described above in steps S10 to S18 and step S20 are repeatedly executed while the forklift 10 is in operation (while the movement control system 1 is running).

[0126] (Effects and Benefits) According to the above, the allowable acceleration is obtained from the correspondence information based on the lifting height and reach length of the cargo handling device 13 of the forklift 10 while it is in motion. Furthermore, if the magnitude of the obtained allowable acceleration is smaller than the magnitude of the maximum acceleration, the reach length is set to a target reach length corresponding to this allowable acceleration, and the forklift 10 is accelerated at a greater acceleration than the initial allowable acceleration before the reach length was changed. As a result, the zero moment point Zmp can be moved to the direction of travel Ds compared to the case where the forks 132 are not protruding, and as a result, the forklift 10 can be moved at a greater acceleration. Therefore, throughput can be improved while suppressing the forklift 10 from tipping over.

[0127] <Second Embodiment> Next, a second embodiment of the operation of the driving control device 20 according to this disclosure will be described with reference to Figure 8.

[0128] (Operation of the driving control system) When the forklift 10 performs cargo handling operations at a target position P where cargo handling operations can be performed, the cargo handling device drive unit 21 drives the cargo handling device 13 (step S101). Specifically, the cargo handling device drive unit 21 causes the cargo handling device 13 to sequentially perform lifting operations (lift down or lift up), reach-out operations, lift-up operations, tilt-up operations, and tilt-down operations. Therefore, in the process of step S101 in this embodiment, reach-in and lift-down operations are not performed by the cargo handling device drive unit 21.

[0129] When the cargo handling device drive unit 21 drives the cargo handling device 13 and the cargo Lg is placed on the forks 132, the cargo information acquisition unit 22 acquires cargo information (step S102). Specifically, before the mast 131 is tilted up, the center of gravity position detection unit 232 of the cargo information acquisition unit 22 detects the center of gravity position CG1 of the cargo Lg in the vehicle width direction Dw, and when the mast 131 is tilted up, the center of gravity position detection unit 232 detects the center of gravity position CG1 of the cargo Lg in the direction of travel Ds.

[0130] Next, the vehicle information acquisition unit 23 acquires the weight of the forklift 10, including the load Lg, and the center of gravity position CG as vehicle information (step S103). Next, the correspondence relationship information acquisition unit 24 acquires correspondence relationship information (step S104).

[0131] Next, the cargo handling equipment information acquisition unit 25 acquires the lifting height of the forks 132 (step S105). Then, the target reach length acquisition unit 28 acquires the target reach length from the correspondence relationship information acquired by the correspondence relationship information acquisition unit 24, based on the lifting height of the forks 132 acquired by the cargo handling equipment information acquisition unit 25 and the maximum acceleration of the forklift 10 which is stored in advance by the storage unit 33 (step S106).

[0132] Next, the cargo handling device drive unit 21 drives the cargo handling device 13 (step S107). Specifically, the forward / backward control unit 212 of the cargo handling device drive unit 21 causes the cargo handling device 13 to perform a reach-in, and the lifting / lowering control unit 211 of the cargo handling device drive unit 21 causes the cargo handling device 13 to perform a lift-down. During this process, the mast 131 is driven so that the position of the forks 132 reaches the target reach length.

[0133] Next, the reach length determination unit 29 determines whether the reach length of the fork 132 has reached the target reach length (step S108). If the reach length determination unit 29 determines that the target reach length has been reached (step S108: YES), the cargo handling equipment information acquisition unit 25 acquires the lifting height and reach length of the fork 132 (step S109). At this time, the reach length of the fork 132 acquired by the cargo handling equipment information acquisition unit 25 is the target reach length acquired by the target reach length acquisition unit 28 in step S106. On the other hand, if the reach length determination unit 29 determines that the target reach length has not been reached (step S108: NO), the process returns to step S107.

[0134] Next, the permissible acceleration acquisition unit 26 acquires the permissible acceleration from the correspondence relationship information acquired by the correspondence relationship information acquisition unit 24, based on the lifting height and reach length of the fork 132 acquired by the cargo handling equipment information acquisition unit 25 (step S110).

[0135] Next, the self-position determination unit 31 determines whether the stopping position of the forklift 10 is before the next target position P (step S111). If the self-position determination unit 31 determines that "the stopping position is before" (step S111: YES), the torque acquisition unit 321 acquires the acceleration torque (step S112). On the other hand, if the self-position determination unit 31 determines that "the stopping position is not before" (step S111: NO), the torque acquisition unit 321 acquires the deceleration torque (step S113). After completing the processes in steps S27 and S28, the torque acquisition unit 321 of the drive wheel control unit 32 acquires the upper limit torque (step S114).

[0136] Next, the torque acquisition unit 321 acquires the instructed torque (step S115). Then, the torque determination unit 322 of the drive wheel control unit 32 determines the drive torque (step S116). Then, the drive wheel drive unit 323 of the drive wheel control unit 32 drives the drive wheels 141 with the drive torque determined by the torque determination unit 322 (step S117).

[0137] The processes described above, from steps S101 to S117, are repeatedly executed while the forklift 10 is in operation (while the movement control system 1 is running).

[0138] (Effects and Benefits) According to the above, when the forklift 10 performs cargo handling operations at the target position P, the target reach length is obtained from the correspondence information based on the lifting height of the forks 132 and the maximum acceleration of the forklift 10. Furthermore, the amount of fork 132 protrusion is set to the target reach length, and the allowable acceleration is obtained from the correspondence information based on the lifting height of the forks 132 and this target reach length, and the forklift 10 is moved at this allowable acceleration. As a result, for example, the forklift 10 can be moved toward the next target position P with a greater acceleration compared to when the forklift 10 is traveling with the forks 132 not protruding. Therefore, throughput can be improved while suppressing the forklift 10 from tipping over.

[0139] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to that of the embodiments, and additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the gist of this disclosure.

[0140] Figure 10 is a hardware configuration diagram showing the configuration of the computer 1100 according to this embodiment. Computer 1100 includes a processor 1110, main memory 1120, storage 1130, and interface 1140.

[0141] The aforementioned driving control device 20 is implemented in the computer 1100. The operation of each processing unit described above is stored in the storage 1130 in the form of a program. The processor 1110 reads the program from the storage 1130, loads it into the main memory 1120, and executes the above processing according to the program. The processor 1110 also allocates a storage area in the main memory 1120 corresponding to the storage unit 33 described above, according to the program.

[0142] The program may be intended to implement some of the functions that the computer 1100 is to perform. For example, the program may perform its functions in combination with other programs already stored in the storage 1130, or in combination with other programs implemented in other devices.

[0143] Furthermore, in addition to the above configuration, or in place of the above configuration, the computer 1100 may also be equipped with a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device). Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor 1110 may be realized by the integrated circuit.

[0144] Examples of storage 1130 include magnetic disks, magneto-optical disks, and semiconductor memory. Storage 1130 may be internal media directly connected to the bus of computer 1100, or external media connected to computer 1100 via interface 1140 or a communication line.

[0145] Furthermore, if this program is distributed to computer 1100 via a communication line, the receiving computer 1100 may load the program into main memory 1120 and execute the above processing. In the above embodiment, storage 1130 is a tangible storage medium that is not temporary.

[0146] Furthermore, the program may be intended to implement some of the functions described above. Moreover, the program may be a so-called differential file (differential program) that implements the functions described above in combination with other programs already stored in the storage 1130.

[0147] Furthermore, the correspondence information acquired by the correspondence information acquisition unit 24 may include a correlation between the lifting height of the fork 132, the reach length of the fork 132, and the slewing speed that positions the zero moment point Zmp within the stable region R1. In this case, the allowable acceleration acquisition unit 26 acquires the allowable slewing speed from the correspondence information acquired by the correspondence information acquisition unit 24, based on the lifting height and reach length of the fork 132 acquired by the cargo handling equipment information acquisition unit 25. The following describes an example of the operation of the driving control device 20 after the correspondence information has been acquired, with reference to Figure 11.

[0148] First, the drive wheel drive unit 323 of the drive wheel control unit 32 drives the drive wheels 141 to move the forklift 10 along the travel path (step S10). The cargo handling equipment information acquisition unit 25 acquires the lifting height and reach length of the forks 132 while the forklift 10 is traveling (step S11).

[0149] Next, the permissible acceleration acquisition unit 26 acquires the permissible slewing speed from the correspondence relationship information acquired by the correspondence relationship information acquisition unit 24, based on the lifting height and reach length of the fork 132 acquired by the cargo handling equipment information acquisition unit 25 (step S12').

[0150] Next, the acceleration determination unit 27 determines whether the magnitude of the allowable turning speed obtained by the allowable acceleration acquisition unit 26 is smaller than the magnitude of the target speed of the forklift 10 (step S13'). Here, "magnitude of the target speed of the forklift 10" means, for example, the magnitude of the turning speed applied to the forklift 10 when the drive motor 141b rotates with the maximum torque that the drive wheels 141 can generate, with no load Lg placed on the forks 132. The target speed is an example of the maximum acceleration of the forklift 10 and is stored in advance, for example, by the storage unit 33.

[0151] If the acceleration determination unit 27 determines that "the allowable turning speed is equal to or greater than the target speed" (step S13': NO), the torque acquisition unit 321 of the drive wheel control unit 32 acquires the instructed speed (step S14'). The torque acquisition unit 321 acquires the smaller of the magnitude of the allowable turning speed and the magnitude of the target speed as the instructed speed.

[0152] On the other hand, if the acceleration determination unit 27 determines that "the allowable turning speed is less than the target speed" (step S13': YES), the target reach length acquisition unit 28 acquires the target reach length of the fork 132 corresponding to the acquired allowable turning speed from the correspondence information (step S18'). Following the processing in step S18', the cargo handling control step S20 described above is executed.

[0153] Following the processing in step S14', the torque determination unit 322 of the drive wheel control unit 32 determines the drive torque (step S15'). The torque determination unit 322 determines the drive torque from the standard deviation of the instructed speed acquired by the torque acquisition unit 321. Next, the drive wheel drive unit 323 of the drive wheel control unit 32 drives the drive wheels 141 with the drive torque determined by the torque determination unit 322 (step S16').

[0154] The series of processes described above are repeatedly executed while the forklift 10 is in operation (while the movement control system 1 is running).

[0155] Furthermore, if the target position P described in the first embodiment is a position where the forklift 10 can load the cargo Lg, the lifting height and reach length of the forks 132 of the forklift 10 when it is traveling without cargo Lg loaded may be the height and protrusion amount that allows for loading the cargo Lg. This makes it possible to shorten the time required to drive the cargo handling device 13 at the target position P, for example. Therefore, the time required for cargo handling operations can be shortened, and throughput can be further improved.

[0156] Furthermore, the operation of the travel control device 20 described in each of the above embodiments is not limited to independent configurations, and the operation of the travel control device 20 may be configured by appropriately combining the operations described in each embodiment.

[0157] <Note> The driving control device described in the embodiment can be understood, for example, as follows:

[0158] (1) A driving control device 20 according to the first embodiment is a driving control device 20 for a forklift 10 comprising: a vehicle 11; drive wheels 141 provided on the vehicle 11 and driven to move the vehicle 11; straddle legs 12 provided on the vehicle 11 and capable of moving together with the vehicle 11; and a cargo handling device 13 provided on the straddle legs 12 and driven to allow the forks 132 to move up and down in the vertical direction Dv and to move back and forth in the direction of travel Ds of the vehicle 11, wherein the driving control device 20 includes: a center of gravity position detection unit 232 that detects the center of gravity position CG of the forklift 10 including the load Lg when a load Lg is placed on the forks 132; a lifting height indicating the position of the forks 132 in the vertical direction Dv, a reach length indicating the amount of protrusion of the forks 132 in the direction of travel Ds, and an acceleration that positions the zero moment point Zmp within the stable region R1 based on the center of gravity position CG; The system includes: a correspondence information acquisition unit 24 that acquires correspondence information relating to each other; a cargo handling device information acquisition unit 25 that acquires the lifting height and reach length of the fork 132; an allowable acceleration acquisition unit 26 that acquires an allowable acceleration from the correspondence information based on the lifting height and reach length acquired by the cargo handling device information acquisition unit 25; a target reach length acquisition unit 28 that acquires a target reach length from the correspondence information based on the lifting height and maximum acceleration when the allowable acceleration is smaller than the maximum acceleration of the forklift 10; a cargo handling device drive unit 21 that drives the cargo handling device 13 so that the reach length of the fork 132 becomes the target reach length; and a drive wheel control unit 32 that drives the drive wheels 141 so that the forklift 10 accelerates at an acceleration greater than the allowable acceleration when the reach length of the fork 132 becomes the target reach length.

[0159] As a result, the permissible acceleration is obtained based on the lifting height and reach length of the cargo handling device 13 of the forklift 10 while it is in motion. If the magnitude of the permissible acceleration is smaller than the magnitude of the maximum acceleration, the lifting height and reach length are set to correspond to this maximum acceleration, thereby accelerating the forklift 10 with a greater acceleration than the initial permissible acceleration before the reach length was changed. Therefore, the forklift 10 can be moved with a greater acceleration.

[0160] (2) The travel control device 20 according to the second embodiment is the travel control device 20 of (1), wherein the forklift 10 travels toward the target position P, which is the loading / unloading position, with no load Lg placed on the forks 132, and the lifting height and reach length of the forks 132 acquired by the loading / unloading device information acquisition unit 25 are the height and protrusion amount that allow the load Lg to be loaded onto the forks 132 at the target position P.

[0161] This reduces the time required to drive the cargo handling device 13 at the target position P. Therefore, the time required for cargo handling operations can be reduced, and throughput can be further improved.

[0162] (3) A driving control device 20 according to a third embodiment is a driving control device 20 for a forklift 10 comprising: a vehicle 11; drive wheels 141 provided on the vehicle 11 and driven to move the vehicle 11; straddle legs 12 provided on the vehicle 11 and capable of moving together with the vehicle 11; and a cargo handling device 13 provided on the straddle legs 12 and driven to allow the forks 132 to move up and down in the vertical direction Dv and to move back and forth in the direction of travel Ds of the vehicle 11, wherein when a load Lg is placed on the forks 132, a center of gravity position detection unit 232 detects the center of gravity position CG of the forklift 10 including the load Lg; and based on the center of gravity position CG, a lifting height indicating the position of the forks 132 in the vertical direction Dv, a reach length indicating the amount of protrusion of the forks 132 in the direction of travel Ds, and an acceleration that positions the zero moment point Zmp within the stable region R1 The system includes: a correspondence information acquisition unit 24 that acquires associated correspondence information; a cargo handling device information acquisition unit 25 that acquires the lifting height of the forks 132 when the center of gravity position CG of the forklift 10 is detected; a target reach length acquisition unit 28 that acquires a target reach length from the correspondence information based on the lifting height of the forks 132 and the maximum acceleration of the forklift 10 acquired by the cargo handling device information acquisition unit 25; a cargo handling device drive unit 21 that drives the cargo handling device 13 so that the reach length of the forks 132 becomes the target reach length; a permissible acceleration acquisition unit 26 that acquires a permissible acceleration from the correspondence information based on the lifting height of the forks 132 and the target reach length; and a drive wheel control unit 32 that drives the drive wheels 141 so that the forklift 10 accelerates at the permissible acceleration when the reach length of the forks 132 becomes the target reach length.

[0163] As a result, for example, when the forklift 10 performs a loading / unloading operation, the target reach length is determined based on the lifting height of the forks 132 and the maximum acceleration of the forklift 10. Furthermore, the amount of fork 132 protrusion is set to the target reach length, and based on the lifting height of the forks 132 and this target reach length, the allowable acceleration is determined, and the forklift 10 is moved at this allowable acceleration. Therefore, for example, the forklift 10 can be moved at a greater acceleration compared to when the forklift 10 is traveling with the forks 132 not protruding. [Explanation of Symbols]

[0164] 1…Movement control system 10…Forklift 11…Vehicle 12…Straddle leg 13…Cargo handling device 14…Driving mechanism 15…Weight sensor 16…Self-position sensor 20…Driving control device 21…Cargo handling device drive unit 22…Cargo information acquisition unit 23…Vehicle information acquisition unit 24…Relationship information acquisition unit 25…Cargo handling device information acquisition unit 26…Allowable acceleration acquisition unit 27…Acceleration determination unit 28…Target reach length acquisition unit 29…Reach length determination unit 30…Self-position acquisition unit 31…Self-position determination unit 32…Drive wheel control unit 321…Torque acquisition unit 322…Torque determination unit 323…Drive wheel drive unit 33…Memory unit 40…Host device 121…Right straddle leg 122…Left straddle leg 131…Mast 132…Fork 141…Drive wheel 141a…Drive wheel body 141b…Drive motor 141c,142b,143b…Steering motor 142…First driven wheel 142a…First driven wheel body 143…Second driven wheel 143a…Second driven wheel body 211…Lifting control unit 211a…Lift-down instruction unit 211b…Lift-up instruction unit 212…Forward / backward control unit 212a…Reach-out instruction unit 212b…Reach-in instruction unit 213…Tilt control unit 213a…Tilt-up instruction unit 213b…Tilt-down instruction unit 221…Load load acquisition unit 222…Load weight calculation unit 223…Load center of gravity position detection unit 231…Weight calculation unit 232…Center of gravity position detection unit 1100…Computer 1110…Processor 1120…Main memory 1130…Storage 1140…Interface D1…Aisle extension direction D2…Aisle width direction Ds…Direction of travel Dsb…Rear side Dsf…Front side Dv…Up and down direction Dvd…Down side Dvu…Up side Dw…Vehicle width direction Dwl…Other side Dwr…One side Lg…Luggage O1…First rotation axis O2…Second rotation axis O3…Third rotation axis P…Target position R…Road surface R1…Stable area R2…Allowable area V1…First virtual line V2…Second virtual line V3…Third virtual line W…Wall Zmp…Zero moment point

Claims

1. Vehicles and, A drive wheel provided on the vehicle and driven to move the vehicle, A pair of straddle legs are provided on the vehicle, are capable of traveling together with the vehicle, are positioned apart in the vehicle width direction, and extend in the front-rear direction of the vehicle, A pair of straddle legs are provided with a first driven wheel and a second driven wheel, which are arranged apart from the drive wheels in the front-rear direction, A load handling device provided on the straddle leg, which is driven so that the forks can be raised and lowered vertically and move back and forth in the direction of travel of the vehicle, A forklift travel control device equipped with, A center of gravity detection unit detects the center of gravity of the forklift, including the load, when a load is placed on the forks. A correspondence relationship information acquisition unit acquires correspondence relationship information relating the lifting height, which indicates the position of the fork in the vertical direction, the reach length, which indicates the amount of protrusion of the fork in the direction of travel, and the acceleration that positions the zero moment point within the stable region, based on the aforementioned center of gravity position. A cargo handling device information acquisition unit that acquires the lifting height and reach length of the fork, Based on the lifting height and reach length acquired by the cargo handling equipment information acquisition unit, an allowable acceleration acquisition unit acquires the allowable acceleration from the correspondence information, When the allowable acceleration is smaller than the maximum acceleration of the forklift, a target reach length acquisition unit acquires a target reach length from the correspondence information based on the lifting height and the maximum acceleration, A cargo handling device drive unit drives the cargo handling device so that the reach length of the fork becomes the target reach length, A drive wheel control unit drives the drive wheels so that the forklift accelerates at an acceleration greater than the allowable acceleration when the reach length of the fork is set to the target reach length, Equipped with, The aforementioned zero moment point is, When the vehicle accelerates, the intersection point of the imaginary extension of the resultant force vector F+G, which is the vector F representing the direction and magnitude of the inertial force acting on the center of gravity in the opposite direction to the direction of acceleration of the vehicle, and the road surface on which the vehicle travels, is the point where the vehicle travels. The aforementioned stable region is A driving control device that, when viewed from above, forms a virtual triangle with its vertices at the positions of the rotation axes extending vertically from the drive wheel, the first driven wheel, and the second driven wheel, respectively.

2. The forklift travels toward the target position, which is the loading / unloading position, with no load placed on the forks. The travel control device according to claim 1, wherein the lifting height and reach length of the fork acquired by the cargo handling device information acquisition unit are the height and protrusion amount that allow the cargo to be loaded onto the fork at the target position.

3. Vehicles and, A drive wheel provided on the vehicle and driven to move the vehicle, A pair of straddle legs are provided on the vehicle, are capable of traveling together with the vehicle, are positioned apart in the vehicle width direction, and extend in the front-rear direction of the vehicle, A pair of straddle legs are provided with a first driven wheel and a second driven wheel, which are arranged apart from the drive wheels in the front-rear direction, A load handling device provided on the straddle leg, which is driven so that the forks can be raised and lowered vertically and move back and forth in the direction of travel of the vehicle, A forklift travel control device equipped with, A center of gravity detection unit detects the center of gravity of the forklift, including the load, when a load is placed on the forks. A correspondence relationship information acquisition unit acquires correspondence relationship information relating the lifting height, which indicates the position of the fork in the vertical direction, the reach length, which indicates the amount of protrusion of the fork in the direction of travel, and the acceleration that positions the zero moment point within the stable region, based on the aforementioned center of gravity position. A cargo handling device information acquisition unit that acquires the lifting height of the forks when the center of gravity position of the forklift is detected, A target reach length acquisition unit acquires a target reach length from the correspondence information based on the lifting height of the forks and the maximum acceleration of the forklift acquired by the cargo handling equipment information acquisition unit, A cargo handling device drive unit drives the cargo handling device so that the reach length of the fork becomes the target reach length, An allowable acceleration acquisition unit that acquires an allowable acceleration from the correspondence information based on the lifting height of the fork and the target reach length, A drive wheel control unit drives the drive wheels so that the forklift accelerates at the allowable acceleration when the reach length of the fork is set to the target reach length, Equipped with, The aforementioned zero moment point is, When the vehicle accelerates, the intersection point of the imaginary extension of the resultant force vector F+G, which is the vector F representing the direction and magnitude of the inertial force acting on the center of gravity in the opposite direction to the direction of acceleration of the vehicle, and the road surface on which the vehicle travels, is the point where the vehicle travels. The aforementioned stable region is A driving control device that, when viewed from above, forms a virtual triangle with its vertices at the positions of the rotation axes extending vertically from the drive wheel, the first driven wheel, and the second driven wheel, respectively.

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