JP2003081595A - Unattended forklift - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an unattended forklift simplified in structure and control, and preventing cargo dragging. SOLUTION: This unattended forklift 1 comprises a pair of forks 6 provided on a vehicular body 2 and vertically ascending/descending, a control device 10, an encoder 1 detecting a traveling distance, and a detecting device 7 comprising a floodlight 7a and a photoreceptor 7b respectively provided tip ends of the pair of the forks 6 and detecting the presence or absence of a load. After detecting the load by the detecting device 7 at the time of a cargo receiving, a forward traveling distance is detected by the encoder 11 and stored in the control device 10. Then, when the forklift is moved backward by the forward traveling distance, it is determined that cargo dragging is absent if the detecting device 7 does not detect the load, and it is determined that cargo dragging is present if the detecting device 7 detects the load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unmanned forklift truck, and more particularly, when unloading, the pallet on which the load is placed is not completely separated from the forks, and the pallet is dragged along with the backward movement of the pallet, and when the work is completed, The present invention relates to an unmanned forklift that prevents a load from being damaged by being dropped.

[0002]

2. Description of the Related Art When loading a pallet on a shelf with a forklift, place the pallet on the shelf with the fork, and level or lower the fork to retract the forklift and leave the pallet with the luggage. I was doing. However, in an unmanned forklift, the operator cannot visually confirm that the fork is separated from the pallet, so when trying to pull out the fork when the fork and the pallet are not separated, the pallet is dragged. May occur. In other words, there is a danger that the cargo will be dragged, and as a result, the luggage will fall from the shelf.

Therefore, conventionally, a sensor is arranged at the tip of the fork or at the base of the fork to operate in contact with the lower surface of the pallet, and the upper surface of the fork must be in contact with the lower surface of the pallet when the sensor stops operating. Judging from the control device installed on the vehicle body, the forks were being moved backwards. However, there is a forward or backward inclination of the forks due to changes in floor surface accuracy and elevation, and it is not always the case that the bottom surface of the pallet and the top surface of the forks contact each other even if the sensor is not operating. The phenomenon of pulling the palette occurred.

Therefore, a light emitting / receiving device is provided on the lift bracket of the forklift to detect the presence / absence of a package in a predetermined range, and a traveling distance detector is provided to detect the traveling distance, and the package is detected based on the detection results. There is a device that determines whether the forklift is dragging or not, and when it determines that the luggage is dragged, it stops the backward traveling of the forklift.

[0005]

In the above-mentioned prior art,
The presence or absence of luggage is detected by the light reflected by the light projector and reflected by the light receiver and received by the light receiver. However, depending on the shape and surface condition of the luggage, it may not be possible to reliably detect the presence or absence of the luggage, and it may not be possible to prevent dragging.

The present invention was devised in view of the above circumstances, and an object of the present invention is to provide an unmanned forklift truck having a simple structure and control and capable of preventing load drag.

[0007]

An unmanned forklift according to claim 1 of the present invention comprises a pair of forks provided on a vehicle body of the forklift and capable of moving up and down, a control device for controlling traveling and cargo handling work, and a forward movement. And a traveling distance detector for detecting the backward traveling distance, and a detection device for detecting the presence or absence of a load at the tip of the pair of forks, and when the forklift is moved forward during unloading, the detection device detects the load. The forward traveling distance after being detected by the traveling distance detector is stored in the control device, and then, when the forklift is retracted at the time of unloading, it is moved backward by the forward traveling distance, and the luggage is detected by the detection device. If this is the case, it is determined that there is a drag drag and the backward running of the forklift is stopped.

Thus, when the forklift is unloading the load, the pair of forks are provided at the tips of the fork to detect the presence or absence of the load and the travel distance detector. The detected forward distance is detected and stored in the control device. After that, at the time of unloading,
When the forklift is moved backward by the forward travel distance, if no load is detected by the detection device, it is determined that there is no load drag, and the work is continued. If the detection device detects the load, it can be determined that there is a load drag and the backward traveling of the forklift can be stopped. As a result, it is possible to prevent the luggage from falling due to the dragging of the cargo. Also,
Since we improved the pair of detection devices that detect the presence of luggage,
Therefore, the detection device and the control device can be simplified.

The unmanned forklift according to claim 2 is the unmanned forklift according to claim 1, wherein the detection device comprises a light projector provided at one end of the fork and a light receiver provided opposite to the other end of the fork. The package is detected by blocking the light projected from the light projector to the light receiver. As a result, the light emitted by the light emitter provided at the tip of one of the forks is directly received by the light receiver provided at the tip of the other fork, so that it is possible to reliably detect the presence or absence of the luggage, and It is possible to prevent luggage from falling due to dragging.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. 1 is a side view of an unmanned forklift truck (hereinafter, also simply referred to as a forklift truck) for preventing load drag according to the present embodiment, FIG. 2 is a perspective view of a fork tip portion thereof, FIG. 3 is a block diagram of its operation control system, FIG. 4 is a process diagram for explaining a work of unloading work by the unmanned forklift of the present embodiment, FIG. 5 is a process diagram for explaining a work of unloading the load, and FIG. 6 is a control method of another embodiment. FIG. 3 is a perspective view of a luggage for.

(Embodiment 1) In an unmanned forklift 1 of this embodiment, straddle arms 3 are provided at both left and right front ends of a vehicle body 2, and a mast 4 is erected vertically on the straddle arm 3. Then, a pair of forks 6 are mounted on the mast 4 via a lift bracket 5 so as to be vertically movable, and a light emitter 7a or a light receiver 7b of the detection device 7 faces the tips 6a and 6b of the pair of forks 6, respectively. It is provided.

A pair of left and right traveling wheels 8 are attached to the front side of the straddle arm 3 and one drive steering wheel 9 is attached to the rear side of the vehicle body 2. Further, on the vehicle body 1, a traveling device (not shown) for driving and driving the drive steered wheels 9, a steering steering device, a cargo handling device, a control device 10 such as a microcomputer for controlling these devices, a traveling distance detection device. The device 11 and the like are built in. Further, a track detecting means 12 such as a magnetic sensor for detecting a guide line laid on the road surface is attached to the bottom surface of the vehicle body 2.

The forklift 1 detects, for example, a signal of a constant frequency generated from a guide line or the like buried in a traveling path by a track detecting means 12 at the lower part of the vehicle body, and outputs the output signal and a central command installed outside the vehicle. While comparing a signal instructed by the device with a predetermined traveling program, the control device 10 controls the vehicle to automatically steer and travel. In addition, the loading and unloading operations of the unmanned forklift 1 are also performed by the control device 1 based on the command signal from the central command device.
It is controlled to be 0.

As shown in FIG. 3, the control device 10 has an arithmetic control unit 13 and a memory 14 for storing various data. The arithmetic and control unit 13 receives the command from the central command device and executes the command so that the memory 14, the encoder 11 as a mileage detector, the track detecting means 12, the traveling device 15, the steering device 16, and the cargo handling device 17 are executed. Etc. are controlled.

The detecting device 7 detects that the projected light is shielded and detects the presence of an object. In this embodiment, as shown in FIG. 2, the projector 7a is attached to each of the tips 6a and 6b of the pair of forks 6.
And the light receiver 7b are provided so as to face each other. The light projector 7a and the light receiver 7b are provided so as to be recessed from the surface of the fork 6 so that the work of the fork 6 is not hindered. Then, the light projected from the light projector 7a is received by the light receiver 7b.
When the light from the light projector 7a is blocked by the pallet (luggage) and is not received by the light receiver 7b, a light blocking signal is output.

The mileage detector 11 uses, for example, a known encoder or the like which detects the number of rotations of the rotating wheel. In this embodiment, the number of rotations of the drive steered wheels 9 of the forklift 1 is counted by the encoder and the number of rotations is calculated to calculate the traveling distance.

The traveling device 15 drives the steering drive wheels 9 so as to allow the forklift to move forward and backward, and the steering device 16 causes the steering drive wheels 9 to be steered.
Reference numeral 7 causes the fork to move up and down, tilt, and move back and forth.

Next, the operation of the unmanned forklift 1 configured as described above will be described with reference to FIGS. First, the control device 10 receives a command from the central command device regarding the type of cargo, the loading location, and the unloading location, and executes traveling of the unmanned forklift and cargo handling work. The forklift 1 is driven by a traveling device and a steering device to travel on a shelf in which a predetermined load is stored, and then the detection device 7 is turned on and moved forward toward the shelf. When the light emitted from the light projector 7a of the detection device 7 is no longer received by the light receiver 7b, a light shielding signal is output to the control device 10 (FIG. 4).
(A)). Here, when the light-shielding signal of the detection device 7 is input, the control device 10 turns on the traveling distance detector 11 and advances the pallet to a position where it can be completely placed on the fork (FIG. 4 (b)). The memory 14 stores the traveled distance. Then, the fork is moved up and down, tilted, and the like to place the pallet on the fork.

Next, when unloading the pallets loaded as described above, the control device 10 causes the forklift 1 to travel to a predetermined unloading place, and performs operations such as vertical movement and tilting of the forks to remove the pallets from the pallets. The fork is released and the pallet is placed on the shelf (Fig. 5 (a)). Therefore,
The detection device 7 is turned on, the forklift 1 is moved backward, and at the same time, the traveling distance detector 11 is turned on. Here, when the backward traveling distance of the forklift 1 becomes equal to the forward traveling distance stored in the memory 14 when loading, it is determined whether the light projected from the projector 7a is received by the light receiver 7b. Let it be detected. At this time, the control device 10
If the light-shielding signal is input at, it is determined that there is a load drag, the traveling device 15 is controlled, the traveling of the forklift truck 1 is stopped, and it is confirmed whether the pallet is normally placed on the shelf. Further, if the light from the light projector 7a is received by the light receiver 7b and it is determined that there is no drag drag (FIG. 5).
(B)), continue operation.

The forklift of the present embodiment configured as described above has a control device for performing work based on a command for loading and unloading work from a central command device,
It has a detection device for detecting a pallet and a traveling distance detector for detecting a traveling distance. Then, when loading the forklift, the forward travel distance traveled after detecting the pallet is calculated. Then, at the time of unloading, the pallet is placed on the shelf, and when the pallet is retracted by the forward traveling distance, the detection device detects the presence or absence of the pallet by light projection and light reception. I'm trying to stop. As described above, since the pair of detecting devices for detecting the presence / absence of the pallet is improved, the detecting device and the control device can be simplified accordingly. Further, it is possible to eliminate the cargo drag and prevent the cargo from being damaged due to the cargo drag dropping or the like.

In the above description, it is explained that whether or not there is luggage is determined when the forward traveling distance when loading the traveling distance detector is equal to the backward traveling distance when unloading. As the traveling distance, in consideration of the distance between the installation position of the detection device and the tip of the fork, it is actually preferable to set the backward traveling distance larger than the forward traveling distance in order to ensure reliability. Since this correction can be performed by the control device, the device does not have to be complicated.

(Second Embodiment) In the first embodiment,
The example in which the forks facing each other are shielded from light over the entire lower surface of the luggage has been described, but in the case of a four-way pallet (for example, as shown in FIG. 6), the drag drag can be prevented as follows. . Since the unmanned forklift 1 is almost the same as that of the first embodiment, detailed description of the parts having the same operation is omitted and the same drawings are used.
The operation will be described with the same reference numerals.

The forklift 1 is driven by driving a traveling device and a steering device on a shelf in which predetermined luggage is stored,
Next, the detection device 7 is turned on and moved forward toward the shelf (direction of arrow in FIG. 6). When the light projected from the light projector 7a of the detection device 7 is no longer received by the light receiver 7b, a light-shielding signal is output to the control device 10. Here, the control device 10
When the light-shielding signal of the detection device 7 is input, the mileage detector 11 is turned on to move the pallet forward to a position where it can be completely placed on the fork. In this case, on the way (A in FIG. 6,
When the projection light is received in B), the encoder 11 counts the number of forward movements to calculate the traveling distance, and the light reception position is stored in the memory 14.

At the time of unloading, even if the detector 7 receives the light projected, the light receiving position stored in the memory 14 (A in FIG. 6,
If it is B), continue the retreat. Then, if the light-shielding signal is output regardless of the light-receiving position, it is determined that there is cargo dragging, the backward movement of the forklift is stopped,
It prevents the luggage from being damaged by being dropped due to dragging.

[0025]

As described above, the unmanned forklift according to the first aspect of the present invention has the following advantages:
A detection device provided at the tip of the pair of forks, a mileage detector provided on the vehicle body, and a control device allow the vehicle to run backwards for a distance equivalent to the forward mileage traveled after detecting the luggage during unloading. Then, the presence or absence of the luggage is determined, and if the luggage is not detected, it is determined that the luggage is not dragged and the work is continued. If a load is detected, it is determined that there is a load drag, and the backward traveling of the forklift is stopped. As a result, it is possible to prevent the accident of dropping the luggage due to the dragging of the cargo. Further, since only one detecting device for detecting the presence or absence of luggage is sufficient, the detecting device and the control device can be simplified accordingly. And

In the unmanned forklift according to claim 2 of the present invention, the light emitted by the light projector provided at one end of the fork is directly received by the light receiver provided at the other end of the fork. Therefore, it is possible to prevent the luggage from falling due to the dragging of the cargo.

[Brief description of drawings]

FIG. 1 shows a side view of an unmanned forklift of the present invention.

FIG. 2 is a perspective view of a tip portion of a fork of the unmanned forklift according to the present invention.

FIG. 3 is a block diagram of the operation control system of the unmanned forklift according to the present invention.

FIG. 4 is a process diagram for explaining a work of picking up an unmanned forklift according to the present invention.

FIG. 5 is a process diagram for explaining an operation of unloading an unmanned forklift according to the present invention.

FIG. 6 is a perspective view illustrating an application example of another embodiment of the unmanned forklift according to the present invention.

[Explanation of symbols]

1 unmanned forklift 2 car body 6 forks 7 Detection device 7a Floodlight 7b light receiver 8 running wheels 9 Drive Steering Wheel 10 Control device 11 Distance detector (encoder) 12 Track detection means (magnetic sensor) 13 Arithmetic control unit 14 memory 15 Traveling device 16 Steering device 17 cargo handling equipment

Claims (2)

[Claims] 1. A pair of forks provided on a vehicle body of a forklift which can be moved up and down, a control device for controlling traveling and cargo handling work, a traveling distance detector for detecting forward and backward traveling distances, and The pair of forks is provided with a detection device for detecting the presence or absence of luggage, and when the forklift is moved forward during unloading, the traveling distance detector detects the forward traveling distance after detecting the luggage with the detection device. Stored in the control device, and then when the forklift is retracted at the time of unloading, it is retracted by the forward travel distance,
An unmanned forklift, wherein if the detection device detects a load, it is determined that there is a drag drag and the backward traveling of the forklift is stopped. 2. The detection device comprises a light emitter provided at one end of the fork and a light receiver provided opposite to the other end of the fork, and the light is blocked from the light emitter to the light receiver. The unmanned forklift according to claim 1, wherein the unmanned forklift is for detecting.