JP7247827B2 - forklift side shift controller - Google Patents

Description

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

For example, Patent Literature 1 describes a forklift equipped with side shift forks. The side shift fork described in Patent Document 1 includes a pair of upper and lower finger bars fixed to a pair of left and right lift brackets, a shifter that can move left and right with respect to these finger bars, and this shifter attached to the finger bars. and a shift cylinder for moving left and right.

JP 2018-177514 A

By the way, in the cargo handling work of a forklift, it is necessary to lift the pallet with the fork while inserting the fork into the central portion in the width direction of the pallet. However, in the automatic operation of a forklift, if the positional relationship between the forks and the pallet is unknown when inserting the forks into the pallet, there is a risk that the pallet will be lifted while the forks are inserted at a position shifted from the central portion in the width direction of the pallet. There is In this case, the pallet held by the forks tends to become unstable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a side shift control device for a forklift that can lift a pallet with a fork inserted in the center of the pallet in the width direction.

One aspect of the present invention is a side shift control device for a forklift that controls a side shift cylinder that moves a pair of forks in the left-right direction when inserting the pair of forks into a pallet, the pallet detection detecting the pallet. , an attitude detection unit that detects the attitude of the pallet relative to the forklift based on the detection data of the pallet detection unit, and the width direction center position of the front of the pallet is obtained based on the detection data of the pallet detection unit. Based on the position of the center in the width direction of the front of the pallet and the posture of the pallet relative to the forklift detected by the posture detection unit, a position calculation unit that calculates the position of the center in the width direction of the back of the pallet, and the pallet obtained by the position calculation unit and the distance between the pallet center line and the center point obtained by the distance calculation unit, a control unit for controlling the side shift cylinder so that the is equal to or less than a predetermined value.

In such a side shift control device, the pallet is detected by the pallet detector, and the attitude of the pallet relative to the forklift is detected based on the detection data of the pallet detector. Then, based on the detection data of the pallet detection unit, the position of the center of the width direction of the front of the pallet is obtained, and based on the position of the center of the width direction of the front of the pallet and the attitude of the pallet with respect to the forklift, the position of the back of the pallet is obtained. The position of the center in the width direction is obtained. Then, the distance between the center line of the pallet passing through the widthwise center positions of the front and back sides of the pallet and the center point between the pair of forks is obtained, and the side shift cylinder is controlled so that the distance is equal to or less than a predetermined value. be. Therefore, the positional relationship between the forks and the pallet is grasped, and the center point between the pair of forks approaches the pallet center line passing through the positions of the widthwise centers of the front and rear surfaces of the pallet. As a result, the pallet can be lifted while the forks are inserted in the central portion in the width direction of the pallet.

Based on the detection data of the pallet detection unit, the position calculation unit obtains the position of the width direction center of the front surface of the pallet in the forklift coordinate system with the specified position of the forklift as the origin as the first pallet center position, and calculates the first pallet center position. to the world coordinate system represented by the latitude and longitude of the earth, and based on the first pallet center position and the attitude of the pallet with respect to the forklift, the position of the width direction center of the back surface of the pallet in the forklift coordinate system is converted to the second The second pallet center position may be determined as the pallet center position, the second pallet center position may be transformed into the world coordinate system, and the distance calculation unit may determine the distance between the pallet center line and the center point in the world coordinate system.

In such a configuration, the position of the width direction center of the front surface of the pallet in the forklift coordinate system is transformed into the world coordinate system, and the position of the width direction center of the back surface of the pallet in the forklift coordinate system is transformed into the world coordinate system. . Then, in the world coordinate system, the distance between the pallet centerline and the center point between the pair of forks is determined. Therefore, when the forklift moves toward the pallet to insert the fork into the pallet, even if the positional relationship between the fork and the pallet changes sequentially, it is not necessary to re-determine the widthwise center positions of the front and rear sides of the pallet. done. Thereby, simplification of calculation processing can be achieved.

The control unit may control the side shift cylinders so that the distance between the center line of the pallet and the center point is equal to or less than a predetermined value before the pair of forks are inserted into the pallet.

With such a configuration, the center point between a pair of forks will be close to the pallet centerline before the forks are inserted into the pallet. Therefore, it is possible to prevent the tip of the fork from contacting the pallet when the fork is inserted into the pallet.

ADVANTAGE OF THE INVENTION According to this invention, a pallet can be lifted in the state which inserted the fork into the center part of the width direction of a pallet.

1 is a schematic plan view showing a forklift equipped with a side shift control device according to an embodiment of the present invention together with a net pallet; FIG. 1 is a schematic configuration diagram showing a side shift control device according to an embodiment of the present invention; FIG. 3 is a flow chart showing details of a control processing procedure executed by the controller shown in FIG. 2; FIG. 4 is a conceptual diagram showing the positional relationship between the fork and the net pallet; FIG. 4 is a conceptual diagram showing a state in which the forks are in contact with the legs of the net pallet;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic plan view showing a forklift equipped with a side shift control device according to one embodiment of the present invention together with a net pallet. In FIG. 1, a forklift 1 includes a vehicle body 2 and a cargo handling device 4 disposed on the front side of the vehicle body 2 for handling a net pallet 3 .

The cargo handling device 4 includes a mast 5 attached to the front end of the vehicle body 2, a pair of forks 8 attached to the mast 5 via a lift bracket 6 and a load bracket 7 so as to be able to ascend and descend, and for lifting the net pallet 3. It has a side shift cylinder 9 (see FIG. 2) for moving the pair of forks 8 in the left-right direction by moving the load bracket 7 in the left-right direction (vehicle width direction) with respect to the lift bracket 6 . The fork 8 is a long type fork longer than the normal type. The cargo handling device 4 also has a lift cylinder for raising and lowering the forks 8, although not shown.

The net pallet 3 is a box-shaped pallet having a substantially rectangular parallelepiped shape for accommodating packages. The mesh pallets 3 are placed in a plurality of rows, for example, on the bed of a truck. Two net pallets 3 are arranged in each row in the depth direction (I direction). Since the fork 8 is of a long type, it is possible to lift the two mesh pallets 3 on the front side and the back side together.

The net pallet 3 has a front surface 3a, a rear surface 3b facing the front surface 3a, and two side surfaces 3c orthogonal to the front surface 3a and the rear surface 3b. The front surface 3 a faces the forklift 1 when the net pallet 3 is lifted by the forks 8 . Legs 39 are provided at four corners at the lower end of the net pallet 3 . When the net pallet 3 is lifted by the forks 8, the forks 8 are inserted between the legs 39 positioned on both left and right sides of the net pallet 3.

A plate 10 extending in the width direction (J direction) of the mesh pallet 3 is attached to the front surface 3 a of the mesh pallet 3 . The plate 10 is provided with two square markers 11 on both left and right sides. Note that the shape of the marker 11 may be rectangular or the like.

FIG. 2 is a schematic configuration diagram showing a side shift control device according to one embodiment of the present invention. In FIG. 2, the side shift control device 12 of this embodiment is mounted on the forklift 1. As shown in FIG. The side shift control device 12 is a device that controls the side shift cylinder 9 when the net pallet 3 is loaded and unloaded by the automatic operation of the forklift 1 . Specifically, the side shift control device 12 controls the side shift cylinder 9 when inserting the pair of forks 8 into the mesh pallet 3 .

The sideshift control device 12 has a camera 13 , a GPS receiver 14 and a controller 15 .

The camera 13 captures an image of the mesh pallet 3 and acquires the captured image data. Specifically, the camera 13 images two markers 11 provided on the front surface 3 a of the mesh pallet 3 . The camera 13 constitutes a pallet detector that detects the mesh pallet 3 . The camera 13 is attached to the load bracket 7, although not shown. Thereby, the camera 13 can move in the horizontal direction together with the fork 8 .

The GPS receiver 14 receives signals from GPS satellites and performs predetermined calculations to determine the current position of the forklift 1 . The GPS receiver 14 has, for example, a GPS compass that measures the direction of the forklift 1 using GPS. The azimuth of the forklift 1 may be measured using another compass.

The controller 15 includes a CPU, RAM, ROM, input/output interface, and the like. The controller 15 has an orientation detection section 16 , a position calculation section 17 , a distance calculation section 18 and a control section 19 .

The attitude detection unit 16 detects the attitude of the net pallet 3 with respect to the forklift 1 based on the captured image data of the camera 13 . The captured image data of the camera 13 corresponds to the detection data of the camera 13 .

The position calculation unit 17 obtains the position of the center of the width direction of the front surface 3a of the net pallet 3 (hereinafter referred to as net pallet 3A) located on the near side based on the captured image data of the camera 13, Based on the position of the center of the front face 3a of the mesh pallet 3A in the width direction and the posture of the mesh pallet 3 with respect to the forklift 1 detected by the posture detection unit 16, the mesh pallet 3 (hereinafter referred to as the mesh pallet 3B) located on the back side is selected. The position of the center of the width direction of the back surface 3b of is obtained.

The distance calculation unit 18 calculates the width direction center position of the front surface 3a of the net pallet 3A and the width direction center position of the back surface 3b of the net pallet 3B obtained by the position calculation unit 17, and the pair of forks 8. Calculate the distance to the center point between

The control unit 19 controls the side shift cylinder 9 so that the distance between the center line of the pallet calculated by the distance calculation unit 18 and the center point between the pair of forks is equal to or less than a predetermined value. Here, the control unit 19 controls the side shift cylinder 9 so that the distance between the center line of the pallet and the center point between the pair of forks becomes zero. Note that the predetermined value may be a positive (+) value close to zero.

FIG. 3 is a flow chart showing the details of the control processing procedure executed by the controller 15. As shown in FIG. This process is executed, for example, when the forklift 1 is positioned in front of the mesh pallet 3 to be handled. In other words, this process is executed before the fork 8 is inserted into the mesh pallet 3 .

In FIG. 3, the controller 15 first acquires captured image data of the camera 13 (step S101). Also, the controller 15 acquires the position information of the GPS receiver 14 (step S102).

Subsequently, the controller 15 detects the posture of the net pallet 3 with respect to the forklift 1 based on the captured image data of the camera 13 (step S103). The posture of the mesh pallet 3 with respect to the forklift 1 is represented by the inclination angle θm of the mesh pallet 3 with respect to the forklift 1, as shown in FIG.

Specifically, the inclination angle θm of the mesh pallet 3 with respect to the forklift 1 is the angle between the front-rear direction of the forklift 1 and the depth direction of the mesh pallet 3 . When the forklift 1 faces the front surface 3a of the net pallet 3 straight, the inclination angle θm of the net pallet 3 with respect to the forklift 1 is 0 degrees.

The inclination angle θm of the net pallet 3 with respect to the forklift 1 is detected from the shapes of the two markers 11 on the captured image data. When the forklift 1 faces the front 3a of the net pallet 3 straight, the shape of the marker 11 on the captured image data is square. However, when the forklift 1 is tilted with respect to the front surface 3 a of the mesh pallet 3 , the shape of the marker 11 on the captured image data becomes a trapezoid corresponding to the tilt angle θm of the mesh pallet 3 with respect to the forklift 1 .

Subsequently, the controller 15 calculates the center position A in the width direction of the front surface 3a of the net pallet 3A on the front side in the forklift coordinate system based on the captured image data of the camera 13, as shown in FIG. S104). The widthwise center position A of the front face 3a of the net pallet 3A on the near side is the center position between the two markers 11 on the front face 3a of the net pallet 3A.

The forklift coordinate system is a coordinate system having a specified position of the forklift 1 as an origin. The specified position of the forklift 1 is the center position of the forklift 1 (for example, the center position of the axle of the front wheel in the vehicle width direction).

The position A of the width direction center of the front face 3a of the net pallet 3A on the front side in the forklift coordinate system (hereinafter referred to as the front center position A of the front side net pallet 3A in the forklift coordinate system) is represented by the following formula: position coordinates (xa, ya ). The front center position A of the net pallet on the front side is the center position of the first pallet.
x a = x m
ya = ym + (-act)

Here, xa is the coordinate of the front center position A of the net pallet on the front side along the longitudinal direction of the forklift 1 . xb is the coordinate of the front center position A of the net pallet on the front side along the left-right direction of the forklift 1; xm is the coordinate of the front center position A of the net pallet on the front side along the front-rear direction of the forklift 1 in the camera coordinate system. ym is the coordinate of the front center position A of the front side net pallet along the left-right direction of the forklift 1 in the camera coordinate system. Note that the inclination angle θm of the mesh pallet 3 with respect to the forklift 1 described above is an angle in the camera coordinate system and an angle in the forklift coordinate system.

act is the amount of side shift of the fork 8 with respect to the reference position of the fork 8 (the amount of movement in the left-right direction). The reference position of the fork 8 is the center position of the forklift 1 in the vehicle width direction. The forks 8 are normally in the reference position. Act is positive (+) when the fork 8 is shifted to the right.

Subsequently, the controller 15 transforms the front center position A of the front side net pallet in the forklift coordinate system into the world coordinate system based on the position information of the GPS receiver 14 (step S105).

The world coordinate system is a coordinate system represented by the latitude and longitude of the earth. In the world coordinate system, the coordinates of the current position of the forklift 1 are (X, Y), and the azimuth of the forklift 1 is θ.

The front center position A of the front side net pallet in the world coordinate system is represented by position coordinates (Xa, Ya) as in the following equation.
Xa=X+xa×cos θ−ya×sin θ
Ya=Y+xa×sin θ+ya×cos θ

Subsequently, based on the front center position A of the mesh pallet on the front side in the forklift coordinate system and the attitude of the mesh pallet 3 with respect to the forklift 1, the controller 15 moves the mesh pallet on the back side in the forklift coordinate system, as shown in FIG. A position B of the center in the width direction of the back surface 3b of 3B is calculated (step S106). The position B of the width direction center of the back surface 3b of the back side net pallet 3B in the forklift coordinate system (hereinafter referred to as the center position B of the back surface of the back side net pallet 3B in the forklift coordinate system) is represented by the following formula: position coordinates (xb, yb ). Note that the center position B of the back surface of the inner mesh pallet is the center position of the second pallet.
xb=xa+P×cos θm
yb = ya + (-act) + P x sin θm

Here, xb is the coordinate of the back surface center position B of the back side net pallet along the forklift 1 longitudinal direction. yb is the coordinate of the back surface center position B of the back side mesh pallet along the left-right direction of the forklift 1 . P is the distance from the front surface 3a of the net pallet 3A on the near side to the back surface 3b of the net pallet 3B on the far side.

Subsequently, the controller 15 converts the back surface center position B of the inner mesh pallet in the forklift coordinate system into the world coordinate system based on the position information of the GPS receiver 14 (step S107). The back surface center position B of the inner mesh pallet in the world coordinate system is represented by position coordinates (Xb, Yb) as in the following equation.
Xb=X+xb×cos θ−yb×sin θ
Yb=Y+xb×sin θ+yb×cos θ

Subsequently, the controller 15 calculates the center point C between the pair of forks 8 in the world coordinate system, as shown in FIG. 4, based on the positional information of the GPS receiver 14 (step S108). Specifically, the center point C between the pair of forks 8 is the center point between the pair of forks 8 at the half length of the forks 8 . A half length position of the fork 8 is an intermediate position in the extending direction (longitudinal direction) of the fork 8 .

A center point C between a pair of forks 8 in the world coordinate system is represented by position coordinates (Xc, Yc) as in the following equation.
Xc=X+Q×cos θ−(−act)×sin θ
Yc = Y + Q x sin θ + (-act) x cos θ

Here, xc is the coordinate of the central point C between the pair of forks 8 along the longitudinal direction of the forklift 1 . yc is the coordinate of the center point C between the pair of forks 8 along the left-right direction of the forklift 1; Q is the distance from the center position of the forklift 1 to the half length position of the fork 8 .

Subsequently, as shown in FIG. 4, the controller 15 controls the pallet center line G passing through the front center position A of the front side net pallet in the world coordinate system and the center position B of the back side of the back side net pallet in the world coordinate system, and the world coordinate system. A distance L between the pair of forks 8 and the center point C in the coordinate system is calculated (step S109). The distance L between the pallet center line G and the center point C is the distance from the center point C to the pallet center line G along the direction orthogonal to the pallet center line G. The distance L is represented by the following formula.
L=((xb-xa)(yc-ya)-(yb-ya)(xc-xa))
/(√((xa−xb)^2+(ya−yb)^2))

Subsequently, the controller 15 determines the side shift amount of the forks 8 by PID control so that the distance L becomes 0 (step S110). At this time, when the distance L>0, the center point C between the pair of forks 8 is located on the left side of the pallet center line G. When the distance L<0, the center point C between the pair of forks 8 is located on the right side of the pallet center line G.

Subsequently, the controller 15 controls the side shift cylinder 9 according to the side shift amount determined in procedure S (step S111).

Here, the posture detection unit 16 executes steps S101 and S103. The position calculator 17 executes steps S101, S102, S104 to S107. The distance calculator 18 executes steps S108 and S109. The control unit 19 executes steps S110 and S111.

In the above, when the forklift 1 is positioned in front of the net pallet 3 , the camera 13 picks up an image of the front surface 3 a of the net pallet 3 . Then, the posture of the net pallet 3 with respect to the forklift 1 is detected based on the captured image data of the camera 13 .

Next, based on the captured image data of the camera 13 and the position information of the GPS receiver 14, the front center position A of the front side of the net pallet in the forklift coordinate system is calculated. converted. Then, based on the front center position A of the net pallet on the front side in the forklift coordinate system, the attitude of the net pallet 3 with respect to the forklift 1, and the position information of the GPS receiver 14, the center position B on the back surface of the back side net pallet in the forklift coordinate system is calculated. , the center position B of the rear side mesh pallet back surface is transformed into the world coordinate system.

Next, in the world coordinate system, the distance L between the center point C between the pair of forks 8 and the pallet center line G passing through the front side net pallet front center position A and the back side net pallet back center position B is calculated. Then, the side shift amount is determined so that the distance L between the pallet center line G and the center point C becomes zero, and the side shift cylinder 9 is automatically controlled according to the side shift amount. As a result, the center point C between the pair of forks 8 is aligned with the pallet center line G.

In this state, although not described in detail, the steering (not shown) may be automatically controlled by a steering control device (not shown) so that the forklift 1 faces straight toward the front surface 3a of the mesh pallet 3. .

After that, by advancing the forklift 1 toward the net pallet 3 , the forks 8 are inserted between the left and right leg portions 39 of the net pallet 3 . Then, the net pallet 3 is lifted by raising the fork 8 by the lift cylinder (described above) of the cargo handling device 4 .

By the way, when the forks 8 are inserted into the net pallet 3 with the center point C between the pair of forks 8 deviated from the pallet center line G, the net pallet 3 is positioned against the forklift 1 as shown in FIG. Depending on the inclination angle .theta.m, the tip of the fork 8 may come into contact with the leg 39 of the net pallet 3A located on the front side. In this case, the net pallet 3 cannot be lifted by the fork 8.

On the other hand, in the present embodiment, the camera 13 captures an image of the mesh pallet 3 and the attitude of the mesh pallet 3 with respect to the forklift 1 is detected based on the captured image data of the camera 13 . Then, based on the captured image data of the camera 13, the front side net pallet front center position A is obtained, and based on the front side net pallet front center position A and the posture of the net pallet 3 with respect to the forklift 1, the back side net pallet A pallet back surface center position B is obtained. Then, the distance L between the center point C between the pair of forks 8 and the pallet center line G passing through the front center position A of the net pallet on the front side and the center position B on the back surface of the net pallet on the back side is obtained, and the distance L is a predetermined value. The side shift cylinder 9 is controlled as follows. Therefore, the positional relationship between the forks 8 and the mesh pallet 3 is grasped, and the center point C between the pair of forks 8 is the center line of the pallet that passes through the front center position A of the front side mesh pallet and the back center position B of the back side mesh pallet. Get closer to G. As a result, the net pallet 3 can be lifted with the forks 8 inserted in the center of the net pallet 3 in the width direction. As a result, the net pallet 3 can be stably lifted. At this time, by controlling the posture of the forklift 1 with respect to the net pallet 3 so that the forklift 1 faces straight toward the front surface 3a of the net pallet 3, the net pallet 3 can be lifted more stably.

In this embodiment, the front center position A of the net pallet in the forklift coordinate system is transformed into the world coordinate system, and the back center position B of the back net pallet in the forklift coordinate system is transformed into the world coordinate system. Then, in the world coordinate system, the distance L between the pallet center line G and the center point C between the pair of forks 8 is obtained. Therefore, when the forklift 1 travels toward the net pallet 3 to insert the fork 8 into the net pallet 3, even if the positional relationship between the fork 8 and the net pallet 3 changes sequentially, the center position of the front side of the net pallet can be maintained. It is not necessary to re-determine A and the back surface center position B of the inner mesh pallet. Thereby, simplification of calculation processing can be achieved.

Further, in this embodiment, before the pair of forks 8 are inserted into the net pallet 3, the side members are arranged so that the distance L between the center line G of the pallet and the center point C between the pair of forks 8 is equal to or less than a predetermined value. Shift cylinder 9 is controlled. Therefore, before the forks 8 are inserted into the net pallet 3, the center point C between the pair of forks 8 approaches the pallet center line G. Therefore, when the fork 8 is inserted into the net pallet 3, the tip of the fork 8 can be prevented from coming into contact with the net pallet 3.

In addition, this invention is not limited to the said embodiment. For example, in the above-described embodiment, the mesh pallet 3 is detected by capturing the image of the marker 11 provided on the front surface 3a of the mesh pallet 3 with the camera 13. However, there is no particular limitation to this form, and deep learning or the like is used. Alternatively, the mesh pallet 3 may be detected from the captured image data of the camera 13 .

Further, the pallet detector for detecting the mesh pallet 3 is not particularly limited to the camera 13. For example, a laser sensor or the like that irradiates a laser toward the mesh pallet 3 and receives the reflected light of the laser may be used. .

In the above embodiment, the front center position A of the mesh pallet on the front side and the center position B on the back surface of the back mesh pallet in the forklift coordinate system are transformed into the world coordinate system, but the configuration is not particularly limited to that, and the forklift coordinate system , the distance L between the center point C between the pair of forks 8 and the pallet center line G passing through the center position A on the front side of the net pallet on the near side and the center position B on the back side of the net pallet on the back side may be calculated. In this case, the center point C between the pair of forks 8 is a fixed value and does not need to be calculated.

In the above embodiment, before the forks 8 are inserted into the mesh pallet 3, the side shift cylinder 9 is moved so that the distance L between the center line G of the pallet and the center point C between the pair of forks 8 is equal to or less than a predetermined value. is controlled, but is not particularly limited to its form, and if it is possible to detect the net pallet 3, the pallet center line G and The side shift cylinder 9 may be controlled so that the distance L between the pair of forks 8 and the center point C is equal to or less than a predetermined value.

In the above embodiment, the net pallet 3A on the front side and the net pallet 3B on the back side are lifted together by the long type forks 8. It can also be applied to a forklift that lifts the net pallet 3.

In the above embodiment, the net pallet 3 is lifted by the forks 8, but the present invention can be applied to a pallet other than the net pallet 3, such as a plastic or wooden flat pallet having two pallet holes into which the forks are inserted. is also applicable.

DESCRIPTION OF SYMBOLS 1... Forklift, 3, 3A, 3B... Net pallet (pallet), 3a... Front, 3b... Back, 8... Fork, 9... Side shift cylinder, 12... Side shift control device, 13... Camera (pallet detector), 16... Attitude detection unit 17... Position calculation unit 18... Distance calculation unit 19... Control unit A... Front side mesh pallet front center position B... Back side mesh pallet rear center position C... Center point G... pallet centerline.

Claims (2)

A side shift control device for a forklift that controls a side shift cylinder that moves the pair of forks in the left-right direction when inserting the pair of forks into a pallet,
a pallet detection unit that detects the pallet;
an attitude detection unit that detects the attitude of the pallet relative to the forklift based on the detection data of the pallet detection unit;
Based on the detection data of the pallet detection unit, the position of the front width direction center of the pallet is obtained, and the position of the pallet relative to the forklift detected by the front width direction center position of the pallet and the posture detection unit. a position calculation unit that obtains the position of the center of the back surface of the pallet in the width direction based on the posture;
a distance calculation unit that calculates the distance between the center point between the pair of forks and the center line of the pallet passing through the positions of the width direction centers of the front and back surfaces of the pallet obtained by the position calculation unit;
The distance between the center line of the pallet and the center point obtained by the distance calculating unit is a predetermined value before the pair of forks are inserted into the pallet while the forklift is positioned on the front side of the pallet. A sideshift control device for a forklift, comprising: a controller for controlling said sideshift cylinder to: The position calculation unit obtains, as a first pallet center position, a position of the width direction center of the front surface of the pallet in a forklift coordinate system having a specified position of the forklift as an origin, based on the detection data of the pallet detection unit. transforming the first pallet center position into a world coordinate system represented by the latitude and longitude of the earth, and based on the first pallet center position and the attitude of the pallet with respect to the forklift, the pallet in the forklift coordinate system; Obtaining the position of the center in the width direction of the back surface as the second pallet center position, transforming the second pallet center position into the world coordinate system,
2. A side shift control device for a forklift truck according to claim 1, wherein said distance calculator calculates the distance between said center line of said pallet and said center point in said world coordinate system .

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