JPS61277598A - Guide for reach type forklift - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for guiding a reach-type forklift by applying oil to a guide wire.

(Prior Art) As shown in FIG. 6, a reach-type forklift truck has seven U-shaped frames 1, and a fork 2 arranged inside the frame 1. Note that the fork 2 can be pushed forward by a hydraulic cylinder (not shown).

Conventionally, when a reach-type forklift with the above configuration is to be driven, parallel guide wires 3.4 are buried in the travel course of the forklift, and pick-up coils are placed at each tip of the frame 1. 5L and 5R detect the magnetic field generated by the induction wires 3 and 40, and each coil 5L and S
The forklift was steered so that the difference in R output was zero.

The coil 5R is installed horizontally at a height h with respect to the guide wire 4 at 5 as shown in FIG. αIt is installed at an angle. In addition, the = coil 5L is also attached to the guide wire 3 in the same manner, so both coils 5L,
sR is in the shape of a letter No.1. The voltage V generated in the coils 5L and 5R attached in this manner is given by the following equation (1).

However, K: Constant L: Distance from directly below the center of the pickup coil to the guide wire Main key 1 The curved line in the graph of Figure 9 has an angle α of 6
The above distance for 0°! ! Curve B shows the change characteristic of the voltage (2) with respect to 1, and the curve B shows the same change characteristic when the angle α is 00.

Now, when the forklift lateralizes to the left, for example, the coil 5L moves away from the guide wire 3 and the coil 5R approaches the guide wire, resulting in a difference in output between the two. -For example, if the forklift changes its angle clockwise,
Since the attitude angle α of the coil 5L with respect to the guide wire 3 is small, and the attitude angle α of the coil 5B with respect to the guide wire 4 is large,
There will be a difference in the output of both coils.

Therefore, the difference in output between each of the above coils 5L and 5L is as follows:
．． Conventionally, based on this output difference, steering was performed so that the output difference became zero, and the forklift was driven over the guide line.

(Problems to be Solved by the Invention) By the way, each of the above-mentioned coils 5L and 5 coils corresponds to the curve A in FIG.
As shown in FIG. 1, the output decreases rapidly as the distance from the guide wire increases, and since the guide wires are installed at an angle α, their detection sensitivity is also low. Therefore, in the past, each coil 5L was used as shown in FIG. 6 for the purpose of improving 87N.

5R, dedicated guide wires 3 and 4 are laid, but laying two guide wires over the entire running course not only requires time and effort, but also significantly increases equipment costs.

(Means for Solving the Problems) In order to solve the problems of the conventional art, in the present invention, a running course FcG of a reach-type forklift is laid, and a guide line is laid in the U-shaped frame of the forklift. First and second pickup coils are disposed at each tip so that the detection direction is vertical, and third and fourth pickup coils are disposed at left-right symmetrical positions behind the frame. Then, the output difference between the first and second coils and the output difference between the third and fourth coils based on the magnetic field of the guide wire are detected, and the side of the forklift relative to the guide wire is detected based on the output difference. The amount of displacement and the amount of change in attitude angle (yaw angle) are detected, and a steering command for correcting course deviation is obtained from these.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a plan view conceptually showing a reach-and-reach type forklift to which a visiting device according to the present invention is applied. As shown in the figure, in this embodiment, a single guide wire 13 is buried in the travel course of the forklift. Further, pick-up coils IIL and IIR are arranged at each tip of the U-shaped frame 10 in such a manner that the detection direction is up and down, and in a manner parallel to the road surface at symmetrical positions behind the frame 10. Pick-up coils 12L and 12B are arranged close to the guide wire 16.

Note that the front wheels 14 and 15 of this forklift are so-called fixed wheels whose direction does not change. Also, the left rear wheel 16
1 is a drive wheel that is rotationally driven by a motor (not shown), and is steered by a steering motor that will be described later. Further, the right rear wheel 17 functions as a so-called caster (following wheel). Further, the fork 18 is moved forward and backward by a hydraulic cylinder (not shown) and lifted by a hydraulic motor (not shown).

FIG. 2 shows each of the above pickup coils 1, IL, -11.
The configuration of the arithmetic circuit 19 that creates and outputs a steering command based on the outputs of R, 12L, and 12R is illustrated.

This arithmetic circuit 19 includes amplifiers 191 and 192 that voltage amplify the outputs of the coils IIL and IIR, a coil 12L,
Amplifiers 193 and 194 that voltage amplify each output of 12R, an arithmetic unit 195 that calculates the output difference of each of the above-mentioned amplifiers IIL and IIR, an arithmetic unit 196 that calculates the output difference of each of the above-mentioned amplifiers 193 and 194, and each of the above-mentioned output differences. a computing unit 197 that calculates the amount of lateral deviation and attitude angle change (hereinafter referred to as the yaw angle) of the forklift with respect to the guide line I based on the amount of lateral deviation and the yaw angle; 198.

Now, when an AC signal is applied to the guide wire 13 and a magnetic field is generated around it, this magnetic field is generated by the coil 11L.

11R1 in the vertical direction as shown in FIG. 3, and the coils 12L and 12R in the horizontal direction as shown in FIG.

The coils IIL and IIR, whose detection directions are up and down, can obtain sufficient output even when the distance from the guide wire 13 is large, as shown by characteristic curve C in FIG.
Although L/12L and 12R exhibit characteristic B in the figure, they are provided close to the guide wire 13, so they can still obtain sufficient output! a-・,・ Now, if we consider the case where the forklift deviates from its course as shown in Fig. 5, the difference in the output of coil IIL, 11) 1 is the difference between the center F of the line segment connecting those coils and the guiding wire 1.
Distance from 3 m! Suggests Xy, also; il 12L, 12B
The difference in output indicates the distance between the center of the line segment connecting them and the guide line 7, Xa.

Therefore, the output of the arithmetic unit 195 indicates the distance in, and the output of the arithmetic unit 196 indicates the distance Xa.

The calculation unit 197 first calculates the following equation (3) based on the outputs of the calculation units 195 and 196, and determines the deflection angle θ of the forklift with respect to the guide line 13.

however,! = Coil IIL, 11 and coil 12L, 1
The following equation (4) is calculated based on the obtained declination angle θ at a distance of 2R and C. The amount of displacement × is determined.

X −'I−H+1Hsinθ However, from point 1ySP; distance to the line segment connecting coils IIL and IIR; lR: distance from point P to the line segment connecting coils 12L and 12R; deviation obtained by the above calculator 197; The angle θ and the distance × are added to a calculator 198. The calculation unit 198 calculates the following formula (5) based on the outputs of the calculation unit 197 indicating the lateral deviation amount X of the yaw angle 01, and generates a steering command for steering the steering drive 16 by pressing the button. is required.

δr=KA (K, −x+ and θ・θ) −(5) However, xA, KJ, and 6: A constant determined as appropriate depending on the traveling speed and structure of the forklift. The above steering command δr is based on the steering servo system 20K. is input.

As a result, the steering motor 21 that changes the steering angle of the steering drive wheel 16 changes the steering angle of the steering drive wheel 16 so that the deflection angle θ and the amount of lateral deviation x become 0, and as a result, the guide line The course deviation of forklift snoring with respect to No. 13 is corrected.

According to this embodiment, the amount of lateral deviation x and the angle of deviation θ of the forklift are constantly determined and corrected in this way. Therefore, the forklift can travel on the guide line 13&C&.

In the above embodiment, the coils 12L and 12R provided at the rear of the forklift are arranged horizontally, but they may be arranged so that the detection direction is vertical, similar to the coils IIL and IIR.

Furthermore, it is of course possible to have a micro combinator perform the function of the processor x9s=19s shown in the embodiment.

(Effects of the Invention) As explained above, according to the guide device for a reach type forklift according to the present invention, a pickup coil having a detection direction in the vertical direction is arranged at each tip of the U-shaped frame of the forklift. However, the amount of deviation at the front of the forklift is detected based on the outputs of these coils. Therefore, the amount of deviation can be detected with high accuracy without providing two guiding wires as in the conventional case, and thereby the equipment cost can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view conceptually showing a reach-type forklift to which the present invention is applied and the arrangement of pickup coils for the forklift, and FIG. 2 is a configuration of an arithmetic circuit that creates a steering command based on the output of the pickup coil. A block diagram showing an example, FIGS. 3 and 4 are conceptual diagrams showing the magnetic field detection mode of the pickup coil, and FIG.
The figure is a conceptual diagram for explaining the operation of the guidance device according to the present invention, and FIG. 6 shows the arrangement of the pickup coil and the installation of the guide wire in a conventional reach-type forklift.
FIGS. 7 and 8 are conceptual diagrams showing the arrangement of the pickup coil shown in FIG. 6 in more detail, and FIG. 9 is a conceptual diagram showing the arrangement of the pickup coil shown in FIG. It is a graph illustrating output characteristics. 10...U-shaped frame, IIL, IIR, 12L. 12R...Pickup coil, 13...Guiding wire,
11L, IIR...Front wheel, 16.17...Rear wheel, 1
9... Arithmetic circuit, 20... Steering servo system, 21...
・Steering motor. Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] A single guide wire laid along the traveling course of a reach-type forklift, and first and second pickup coils arranged at each tip of the U-shaped frame of the forklift in such a manner that the detection direction is up and down. , third and fourth pickup coils disposed at symmetrical positions behind the frame, and the first pickup coil based on the magnetic field generated by the guide wire.
, the output difference of the second pickup coil and the third,
The output difference of the fourth pickup coil is detected, and the amount of lateral deviation and the amount of change in attitude angle of the forklift with respect to the guide wire are respectively detected based on the output difference, and the amount of lateral deviation and the amount of change in attitude angle are detected. A guide device for a reach-type forklift, comprising: calculation means for calculating a steering command for correcting course deviation based on the steering command; and means for steering the forklift based on the steering command.