JPS5926899A - Travelling stopping and pallet hole searching method in unmanned 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 The present invention relates to a method for stopping an unmanned forklift and digging holes in a pallet.

Conventionally, in unmanned forklifts, when the forklift is moved a certain distance in front of the cargo loaded at the cargo storage position on the ground, this is detected by a sensor such as a light reflection method attached to the tip of the fork, etc. These two detection signals are used to stop the forklift, and then the fork is raised and a hole in the pallet at a predetermined position is detected by a sensor such as the tip of the fork (another light reflection method installed). It was about noon to stop.

However, the conventional control method has the disadvantage that the structure is complicated because two types of sensors, one for stopping traveling and the other for digging holes in the pallet, must be provided.

The object of the present invention is to provide a type of light reflection sensor (an unmanned sensor that can simplify the structure by using the characteristics of the distance and output voltage to stop the forklift and dig into the pallet). An object of the present invention is to provide a method for stopping a forklift and digging a hole in a pallet.

Hereinafter, one embodiment embodying the present invention will be explained using two figures 1 to 4. In the figure, 1 is a guide cable (illustrated path) laid in advance on the ground R* (along which an unmanned guide is carried out). The unmanned forklift is equipped with a pair of left and right forks 4 and 5 that are moved up and down by a lift cylinder 3 at the front of a vehicle body 2.

The cargo W is placed at the cargo storage position on the ground R via the first pallet) Pl.
1 is placed on the second pallet P, and the upper surface 4 of the cargo W1 is
The cargo W2 is placed through the container 2.

As shown in FIG. 2, a first sensor 8 and a second sensor 9 of a light reflecting type consisting of a light emitter 6 and a light receiver 7 are attached to the tips of the pair of forks 4 and 5, respectively.

These sensors 8 and 9 detect light beams emitted from the projector 6 that are reflected from the surface of the load W1 and enter the light receiver 7, and are detected by the difference in distance between the surface of the load W1 and the tips of the forks 4 and 5. As shown in FIG. 3, the output voltage V changes (i.e., r+
IJ recording distance 1! As IL becomes longer, the output voltage (2) increases proportionally, and this output voltage (2) is outputted as a distance signal in the njj direction. Note that the output voltage can be inversely proportional, but proportional output is used as a fail-safe in case of wire breakage, etc.

FIG. 4 shows a driving control circuit for an unmanned forklift and a hole digging control circuit for pellets Pi and P2, and 10 to 13 are first to fourth comparators, and the first to fourth comparators 10 and 11 are is configured such that the output voltage V from the first sensor 8 is input, and the output voltage V from the second sensor 9 is input to the third and fourth comparators 12 and 13. It has become. Also, the above-mentioned
A constant voltage v1 is inputted to the third comparators 10 and 12 from a separately provided constant voltage generation circuit (the circuit shown in the figure), and a constant voltage v2 is inputted to the second and fourth comparators 11 and 13. It has become.

A first OR circuit 14 for outputting a forklift deceleration signal S5 is connected to the second and third comparators 10 and 12, and a second and fourth comparator 11,
13 is connected to a second OR circuit 15 for outputting a forklift stop signal S6. Furthermore, an AND circuit 16 is connected to the first and third comparators 10 and 124 for outputting a pallet digging signal S7.

Next, the operation will be described in the case where the unmanned forklift configured as described above picks up the second-tier cargo W2.

Now, when the unmanned forklift is being guided at high speed in the direction of approaching cargo W1 along the guidance cable (the illustrated path), the distance between cargo W1 and the fork 4°5 is 400.
When the voltage V output from the second and second sensors 8 and 9 becomes vl, the second and third comparators 1
Operation signals S1 and S3 are outputted from 0 and 12, and a deceleration 1 word S5 is outputted from the first 0R circuit 14, and the forklift is switched from high speed to low speed. At this time, the operation signal S1. S3 is also input to the AND circuit 16, and the A
The hole digging signal S7 is output from the ND circuit 16, but since the travel of the forklift is being controlled, this signal is rendered invalid by the control circuit (the path shown).

Further, when the forklift moves forward and the IJ recording distance becomes 200 mm, and the voltage V output from the second and second sensors 8°9 becomes v2, the second and fourth comparators 11, 13 outputs operations 4ttS2 and S4, and therefore a stop signal S6 is output from the second OR circuit 15, and the forklift moves the load W1's hand f'l'lJ.
It is stopped at 200 mm.

Note that in this embodiment, the first and second OR circuits 14.1
5 is used, so if the output voltage of either one of the first and second sensors 8 and 9 becomes Vl or ■2,
The first 0R circuit 14 also outputs the deceleration signal S5, and the second OR circuit 15 outputs the stop signal S6.

The control circuit (as shown) synchronizes with the stop of the forklift.
A command signal for raising the forks 4, 5 to the second pallet P2 is outputted from the forks 4, 5, and the forks 4, 5 are raised at high speed. When the forks 4 and 5 are moved a certain distance downward from the second pallet P2 from the start of the fork 1's rise, the forks 4 and 5 move from high speed to low speed.
-, and at the same time, the output from the AND circuit 16 (1 knot hole searching signal S7) acts as a valid signal, and the - and second OR circuits 14, 15
The signal S5. output from S5. The control circuit (path shown) is switched so that S6 becomes an invalid signal.

Forks 4 and 5 rise at low speed to reach the second stage (let P).
2, the light rays irradiated from the floodlights 6 of the first and second sensors 8 and 9 are moved to the position corresponding to P.
2, the voltage V output from both sensors 8 and 9 becomes higher than Vl, and therefore the operating signals S1 and S3 from the first and third comparators 10 and 12 become AN
D circuit 16 (this is input, and the pallet hole probing signal S7 is output from the circuit 16. After a minute time has elapsed from this hole probing signal S7, the lifting of the forks 4 and 5 is stopped.
The forks 4 and 5 are stopped at positions corresponding to the vertical centers of the holes in the pallet, and the digging operation is completed.

Now, in the embodiment of the present invention, first and second sensors 8 and 9 of the same type are attached to the forks 4 and 5, and these sensors 8 and 9
Since traveling control and pallet digging control are carried out depending on the magnitude of the voltage V output from the pallet, it is only necessary to use one type of sensor, and the structure can therefore be simplified accordingly.

In addition, although two sensors 8 and 9 were used in the above embodiment,
In this way, when the pallet P2 is not horizontal, it is possible to prevent cargo from being picked up with one of the forks not corresponding to the pallet holes, and safety can be improved.

Further, the present invention can also be embodied in the following embodiments.

(1) The first and second OR circuits 14 and 15 shown in FIG. 4 are also subjected to AND circuit numbers.

(2) As shown in FIG. 5Q, only one sensor 8 is used (configured in this way.
0, a stop signal S6 is output, a deceleration signal S5 is output from the comparator 11, and a pallet hole digging signal S7 is also output from the comparator 11.

As described in detail above, the present invention detects the distance between the fork and the load placed at the cargo storage position on the ground using a light reflection type sensor attached to the fork tip of an unmanned forklift. When the distance signal reaches a certain value, the traveling is stopped, and then the fork is moved up and down so that the hole in the cargo loading pallet corresponds to the fork, and the distance signal from the sensor is different from the specified value. When a predetermined value is reached, a pallet hole probing signal is output, which has the effect of simplifying the structure by using only one type of sensor.

[Brief explanation of the drawing]

Fig. 1 is a right side view showing an overview of the unmanned forklift according to the present invention, Fig. 2 is a perspective view showing the sensor in an expanded state, Fig. 3 is a graph showing the distance-output voltage characteristic of the sensor, and Fig. 4 is a graph showing the distance-output voltage characteristic of the sensor.
The figure is a control circuit diagram for traveling and pallet hole digging, and FIG. 5 is an 11i13 control circuit diagram showing a separate version of the present invention. Fork 4, 5, first (second) sensor 8 (9), first ~
Fourth comparator 10 to 13, first (second) OR circuit 1
4 (15), AND circuit 16, distance L, output voltage ■, voltage Ml, V2, deceleration signal S5, lift stop signal S6, pallet hole probing signal S7゜Patent application hole Ya111 Automatic Loom Manufacturing Co., Ltd. Meiden Patent attorney Hironobu On III

Claims (1)

[Claims] 1. The distance between the fork and the cargo placed at the cargo storage position on the ground is detected by a light reflection sensor attached to the tip of the fork of an unmanned forklift, and the distance signal becomes a constant value. Then, the fork is moved up and down so that the hole in the cargo loading pallet and the fork correspond to each other, so that the distance signal from the sensor 01 changes to another predetermined value different from the constant value. 2. Distance from a pair of sensors attached to the tips of each of a pair of left and right forks. A method for stopping traveling and pallet hole digging in an unmanned forklift according to claim 1, wherein a pallet hole digging signal is output from an AND circuit when both signals exceed a predetermined value ζ.