JPS5986600A - Method of searching hole of pallet 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 detecting holes in pallets in an unmanned forklift.

Conventionally, an unmanned forklift has been used to pick up loads W1. loaded in three tiers as shown in FIG. W2. When picking up the load W3, the fork F is raised to the top load W3. Then, when it rises, a hole probe installed at the tip of the fork F @
At S, the hole Ph of the third pallet P was set to detect the fork insertion position.

The hole detecting device S conventionally includes a light emitting element and a light receiving element, and detects a hole Ph based on the presence or absence of reflection of light emitted from the light emitting element.

Therefore, in the case of loads loaded via each pallet P as shown in FIG. 1, there was no particular problem when detecting the hole ph in the pallet P while raising the fork F.

However, as shown in FIG. 2, the load W2. When picking up cargo W3 using the above method, there is a problem that the hole detection device S mistakenly detects the gap between the cargo W1 and the rack R1 and the gap between the cargo W2 and the rack R2 as a hole ph in the pallet P on the way up. Ta.

An object of the present invention is to solve the above-mentioned problem, and by detecting the hole in pallet 1 without lowering the fork, it is possible to accurately stop the fork at the fork insertion position. To provide a method for detecting a hole in a pallet in an unmanned forklift, which enables cargo picking work to be carried out safely, reliably, and quickly.

An embodiment embodying the present invention will be described below with reference to the drawings.

In Fig. 3, the body frame 2 of the unmanned forklift 1
A bearing attached to the axle of the front wheel 3 on the front side supports the outer mast 4 via a tube (not shown) so as to be tiltable in the front-rear direction. The tilt cylinder 5 has its base end rotatably connected to the front upper surface of the vehicle body frame 2, and the tip of the piston rod 5a of the tilt cylinder 5 is rotatably connected to the outer surface of the outer mast 4. ing. Therefore, when the piston rod 5a of the tilt cylinder 5 is retracted when the outer mast 4 is in the vertical position shown in FIG. Then, the outer mast 4 is tilted forward.

An angle detection device 6 consisting of a potentiometer or the like is provided on the outside of the base end of the tilt cylinder 5, and as the piston rod 5a of the tilt cylinder 5 contracts or expands, the tilt cylinder 5 is 5b
The angle of the fork 14, which will be described later, is detected by detecting the rotation position of the fork 14, which will be described later.

The lift cylinder 7 is fixedly installed inside the rear part of the outer mast 4, and the tip of its piston rod 7a (as shown in FIGS. It is fitted and fixed to a connecting member 9 fixed to the upper part of the rear surface.A lift bracket 10 is mounted on the inside of the inner mast 8, as shown in FIG. A fork 14 is attached to the rift 1 to the bracket 10 via upper and lower finger bars 12 and 13.

Further, on the rear surface of the inner mast 8, as shown in FIG.
A mounting block 15 is fixed between the blocks 1 and 1.
5, a chain wheel 16 is rotatably supported by a support shaft 17.

Then, both ends of the lift chain 20 are connected to the mounting bracket 18 attached to the upper part of the lift cylinder 7 and the mounting bracket 19 attached to the rear edge of the lift bracket 1o, and the intermediate part is connected to the mounting bracket 19 attached to the rear edge of the lift bracket 1o. It is hung on the wheel 16.

Therefore, when the piston rod 7a of the lift cylinder 7 is driven in the vertical direction, the inner mast 8 and the chain wheel 16 are moved up and down, and the fork 14 is moved to the inner mast 8 via the lift chain 20. It moves up and down at twice the speed. At this time, the chain wheel 16 is moved by the amount of movement of the lift chain 20, that is,
It is rotated in proportion to the amount of movement of the fork 14.

In FIG. 5, a support arm 21 is fixed to the rear surface of the inner mast 8, and a lifting height detection device 22 consisting of a rotary encoder is attached to the tip attachment portion 21a of the support arm 21. The input shaft 22a of the lift height detection device 22 is interlocked with the chain wheel 1G, and the fork 14 is moved up and down by the lift cylinder 7, and the chain wheel 16 is moved forward and backward in proportion to this. On the other hand, in conjunction with this, the input shaft 22a of the lift height detection device 22 is also rotated in the forward and reverse directions.Then, based on the rotational force direction and rotation maximum of the input shaft 22.'l, the amount of elevation and height of the fork 14 is The lift height detection device 22 outputs a signal for position detection.

A microswitch 23 is attached to the lower end of the outer mast 4 as shown by the broken line in FIG. The same micro switch 23
It is designed to turn on. In this embodiment, when the fork 14 reaches a raised height position of 30 cm (the height position of the running posture), the dock 24 in front turns on the microswitch 23, and the microswitch 23 outputs an on signal. It is designed to let you do so.

On the tip surface of the leaf 14, there is a mark t J shown in broken line in FIG. 3.
: A hole detection sensor 25 consisting of a sea urchin light emitting diode and a phototransistor is provided to detect the hole Ph of the pallet P and detect the insertion position of the fork 14. As shown in FIG. 3, on the outer surface of the outer mast 4, there are first and second stage number sensors 26, 2 as load detection sensors each consisting of a light emitting diode and a phototransistor.
7 is attached forward and upward so that its angle can be adjusted.

Then, the loads W1. Among W2゜W3, to the second and third tier cargo\/2. By irradiating light onto W3 and receiving the reflected light with a phototransistor, the load W2. Detects the presence or absence of W3.

Next, an electric circuit of a control device for driving and controlling the lift cylinder 7 installed in the unmanned forklift 1 will be explained.

In FIG. 6, a fork elevation control circuit 31 receives an ON signal from the microswitch 23 and a detection signal from the lift height detection device 22. When the fork lift control circuit 31 receives the ON signal, the fork lift control circuit 31 changes the contents of the built-in counter to 30 (30).
At the same time, the content of the counter is adjusted based on the detection signal from the lifting height detection device 22 to calculate the lifting height position of the fork. Further, the fork elevation control circuit 31 determines the position of the pallet P by inputting the detection signal from the hole detection sensor 25.

Furthermore, the fork elevation control circuit 31
Detection signals from the stage number sensors 26 and 27 are input, and based on these detection signals, predetermined data is read from a readable and replaceable memory (hereinafter referred to as RAM) 32, and a read-only memory (hereinafter referred to as ROM) is read out. 33).

The RAM 32 stores various data, and in this embodiment, as shown in FIG. 7, data 11.
4 HO, data α for raising the fork 11 to a higher position than the same pallet P, data High-speed ascent data for lowering the fork 14 at a low speed and low-speed lowering data for lowering the fork 14 at a low speed are stored.

The actuator drive circuit 34 drives and controls the lift cylinder actuator 35 based on the drive control signal from the fork elevation control circuit 31 to control the elevation speed of the lift cylinder 7, that is, the fork 14.

Next, the fork elevating control circuit 31 configured as described above
The effect of this will be explained.

Now, as shown in FIG. 7, loads W1.
'W2. The case where W3 is picked up will be explained. First, the unmanned forklift 1 carries the load W1°W2. While stopped at the forward position of Vl/3, the first and second stage number sensors 26 and 27 detect three loads Wl, W2 . W3 is the product - F
When the fork elevating control circuit 31 determines that the fork is being lowered, the fork elevating and lowering control circuit 31 operates according to a flowchart not shown in FIG.

The fork lift control circuit 31 receives data MHO of the lifting height at the center position of the hole 1''h of the third pallet P from the RAM 32, and the fork 14 at a position higher than the pallet P.
Read the data α etc. for increasing the
A first lift height 1 direct MH1 is calculated by adding the values of HO and data α, and the lift height value M1-11 is stored in a register built in the control circuit 31. The fork lift control circuit 31 then reads the high speed lift data from the RAM 32 and outputs a drive control signal to the actuator drive circuit 34 based on the data. The actuator drive circuit 34 operates the lift cylinder actuator 35 in response to the signal.
is driven to raise the fork 14 at high speed.

At the same time as the fork 14 rises at high speed, the lifting height detection device 22
A detection signal is output from. Fork lift control circuit 31
This detection signal is counted by a counter of the fork lift control circuit 31, and the lift height position of the fork 14 at any given time is determined from the count contents.

Eventually, when the content of the counter, that is, the lift height value of the fork 14 matches the lift height value Ml-11 of zl set in the register, the fork elevation control circuit 31 outputs a drive control signal to the actuator drive circuit 34 to stop the fork. to immediately stop the fork 14. At the same time as stopping the fork 14, the fork elevation control circuit 3
1 resets the contents of the register and the second
The lift height value 'MH2 is calculated. This second lift value MH2
In this embodiment, is a position below the pallet P, and is the value obtained by subtracting the data α from the data MHO. After calculating the second lifting height value MH2, the fork elevation control circuit 31 sets the value in the register.

After setting the second lifting height value MH2 in the register, the fork elevation control circuit 31 reads the low speed descending data from the RAM 32. Fork lift control circuit 31
Based on this data, outputs a drive control signal to the actuator drive circuit 34 to lower the fork 14 at a low speed.

The actuator drive circuit 34 drives the lift cylinder actuator 35 in response to this signal, and lowers the fork 14 at a low speed with the second lifting height value N4H2 as a target value.

The fork 14 starts descending from the lifting height MH1, and when the fork 15 reaches the upper edge position of the opening of the pallet P, the fork 14
The hole detection sensor 25 installed at the tip of the hole p of the pallet hP
Detect h. In response to the detection signal from the hole detection sensor 25, the fork lift control circuit 31 obtains the lift height position of the fork 14 at that time from the counter, sets this as a third lift height value CNTPO, and stores it in the RAM.
32, data α of one half of the length of the hole Ph of the pallet P in the downward direction is read out.

Next, the fork elevating control circuit 31 performs the seventh calculation to calculate the fork insertion position CNT (-M to 10) based on both of these data. That is, the fork lift control circuit 31 sets the value obtained by subtracting the value of data X from the third lifting height value CNTR0 in the register.

When the fork elevating control circuit 31 determines that the lowered fork 14 has finally descended to the fork insertion position CNT by comparing it with the contents of the counter, it resets the contents of the register to 0 and also resets the contents of the register to 0.
A drive control signal for stopping the actuator 4 is output to the actuator drive circuit 34. The actuator drive circuit 34
immediately stops the fork 14 in response to the control signal.

Therefore, the fork 14 is at the fork insertion position C; n T
That is, the hole searching operation is stopped in front of the center position of the hole Ph of the pallet P, and the hole searching operation is completed.

In this embodiment, the fork 14 is raised to the first lifting height position MH1 where the load W3 is partially loaded, and then lowered. does not pass through a space other than the pallet P, and only the hole Ph in the pallet P can be reliably detected. Further, since the fork 14 is raised at a high speed, the time required for searching the hole can be shortened.

Furthermore, in this embodiment, when the hole detection sensor 25 provided at the tip of the fork 14 detects the hole ph in the pallet P, the third lifting height position CNTR0 is approximately half the thickness of the pallet l-P, that is, the data The A-ri 14 can be inserted into the pallet P without contacting the inner wall thereof.

Furthermore, if the method of this embodiment is applied to detect holes in the pallets 1 to P of the load W3 placed on the rack R2-]2 shown in FIG.
Rack R2 and load W2 generated by the conventional hole detection method of detecting holes Ph in one pallet while keeping the fork 14 on its back
There is no problem of erroneously detecting the hole R11 of the pallet P due to the gap between them, and hole searching can be performed accurately and accurately.

This invention is not limited to the above embodiments, but can also be implemented in the following embodiments.

(1) Data α1 that determines the first lift height value MH1 (=MHO+α1), second lift height position MH2 (=M'l-10-
data β1 for determining β1), medium speed raising data VUM for raising the fork 14 at low speed, and fork lift 14
Very slow descent data vDD for slow descent is stored in the RAM 32.

Based on these data, as shown in FIGS. 9 and 10, the fork 14 is moved at high speed from the second lifting height position MH2 to the first lifting height position MHI. Alternatively, the fork 14 may be lowered at a very slow speed after being raised at a medium speed.

(2) A fourth lifting height position MH3 (=MHO
+γ), and the data γ for that purpose is stored in the RAM 32.

Then, as shown in FIGS. 11 and 12, the fork 14 is moved upward at high speed to the fourth lifting height position Ml-13, and from the fourth lifting height position MH3 to the first lifting height position. MHI
14 at low speed.
As described in detail, this invention raises the fork to a preset load position and then lowers the fork to detect holes in the pallet. By doing so,
The fork insertion position can be accurately detected, and loading operations can be carried out safely, reliably, and quickly.
This is an industrially accepted method for detecting holes in pallets for unmanned forklifts.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing the loading state for explaining the present invention, Figure 3 is a side view of an unmanned forklift embodying the invention, and Figure 4 shows the fork installation state. 5 is an enlarged front view showing the installation state of the lifting height detection device, FIG. 6 is an electric block circuit diagram of the lift A-lifting device, and FIG. 7 is a diagram for explaining the lifting and lowering operation of the fork. Explanatory diagram, FIG. 8 (J is also a flowchart diagram, FIG. 9 is an explanatory diagram for explaining the fork raising and lowering operation showing another example of this invention, FIG. 10 is also a flowchart diagram, and FIG. 11 is also a diagram of this invention) FIG. 12, an explanatory diagram illustrating another example of the fork raising and lowering operation, is also a flowchart. Hole detection sensor 25, stage number sensor 26, 27, fork elevation control circuit 31, RAM 32, acticoator drive circuit 34, pallet P1 load W1. W2, W3゜Patent applicant Toyota Industries Corporation Meiden Shashiro Patent attorney On 1) Hironobu No. 1 Zukan 2 Fig. 4 Fig. 8th Fig. 5 Fig. 8th @7 Fig. 8 Fig. 8

Claims (1)

[Claims] 1. A load detection sensor installed in the unmanned forklift detects the load in front, and based on this detection, the fork is raised to a preset load position, and then the fork is lowered to the same position. A method for detecting holes in a pallet in an unmanned forklift, characterized in that a hole detecting sensor provided on a fork detects holes in a pallet on which a load is placed. 2. The load detection sensor is a tier sensor that detects the number of loaded loads, and the fork lifts up to a preset load position of the uppermost load based on the detection. A method for detecting holes in a pallet in an unmanned forklift according to claim 1. 3. The unmanned vehicle according to claim 1 or 2, wherein the lifting speed of the fork is decelerated at a preset lifting position while lifting the fork to a preset lifting position. How to find holes in pallets using a forklift. 4. The fork descends by a predetermined distance from the position where the hole detection sensor detects the hole in the pallet, and then stops.Claims 1 and 2
The method for detecting holes in a pallet as described in Section 3 or Section 3. 5. The fork is lowered at a lower speed than the rising speed of the fork.Claim 1
A method for detecting holes in a pallet in an unmanned forklift according to any one of items 1 to 4.