JPH0334088B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the attitude of an unmanned forklift.

In recent years, unmanned forklifts have been made to automatically travel along travel guidance cables that have been laid in advance on the road surface, and to automatically travel to loading positions along cargo handling guidance cables that branch from the travel guidance cables to unload cargo. Unmanned forklift cargo handling systems are becoming popular.

However, in this cargo handling system,
If a forklift that runs along a cargo handling guide cable meanderes and is stopped at an angle with respect to the cargo handling cable to perform a cargo loading operation, the cargo will not only be loaded in an unstable condition, which may be dangerous, but also cause damage to the cargo. There was a defect that caused support during the installation work.

In addition, unmanned forklifts travel from the traveling cable to the cargo handling cable while turning, and do not become parallel to the cargo handling cable unless they travel a certain distance after entering the cargo handling cable, but this makes the cargo storage area more efficient. If you want to use it, it is better to place the cargo as close as possible after the unmanned forklift is moved to the cargo handling cable. However, the closer the unmanned forklift gets, the more the unmanned forklift will remain at an angle with respect to the cargo handling cable, which not only causes cargo to be loaded in an unstable state as mentioned above, but also impedes the cargo handling operation. There was a defect.

The present invention has been made in order to eliminate the above-mentioned defects, and the purpose is that when an unmanned forklift that has automatically traveled along a cargo handling cable approaches a cargo storage position, the unmanned forklift automatically moves along a cargo handling guidance cable. On the other hand, if the forklift is tilted (not in a parallel state), by moving the forklift backwards and then moving it forward, the attitude of the unmanned forklift can be controlled to stop it at the normal cargo handling position and stabilize it. An object of the present invention is to provide a posture control method for an unmanned forklift capable of carrying out cargo loading and unloading operations.

Hereinafter, an embodiment embodying the present invention will be described with reference to the drawings. Reference numeral 1 in FIG. 1 is a traveling guidance cable laid in a loop shape along the traveling route in the center of the traveling route. It is connected to a control device (not shown) on the ground station side that controls the running of the vehicle, and a guidance signal of a predetermined frequency f1 is applied thereto. 2 is a first command coil disposed in the middle of the traveling guidance cable 1,
It is also connected to the control device on the ground station side. 3
is the loading position on the ground from the vicinity of the first command coil 2.
A cargo handling guidance cable laid from P1 to P3,
It is also connected to the control device and has a predetermined frequency f.
2 guidance signals are added.

Reference numeral 4 denotes a second command coil disposed in the middle of the cargo handling guidance cable 3, and is connected to a control device on the ground station side. Reference numeral 5 denotes a corner running guidance cable arranged in a quarter-arc shape to connect the first command coil 2 and the second command coil 4, and is connected to a control device on the ground station side, and is connected to a predetermined frequency f1.
A guidance signal is now added. Reference numeral 6 denotes a stop cable laid in the middle of the cargo handling cable 3 so as to run perpendicular to the cable 3, and is connected to a control device on the ground station side so that a stop signal of a predetermined frequency f3 is applied. . Each of these cables 1, 3, 5, and 6 is connected to a cable selection control circuit (not shown) on the ground station side, and a guidance signal is applied only to the necessary cables.

In Fig. 2, 7 is each cable 1 mentioned above,
5 and 3, the fork 1 is operated by a lift cylinder 9 and is moved up and down by a lift cylinder 9.
0 is attached. Denoted at 12 and 13 are lateral displacement detection coils constituting a cable sensor attached to the bottom of the forklift 7, and as shown in FIG. 3, a pair of coils are provided at the front and rear of the vehicle body. Based on the signals output from these detection coils 12 and 13, a steering control device (not shown) is operated to cause the forklift 7 to travel unmanned along the cables 1, 5, and 3.

Reference numeral 14 denotes a communication device consisting of a receiving coil 15 and a transmitting coil 16 attached to the bottom surface of the central part of the vehicle body, and communicates with the first and second command coils 2 and 4, respectively, and controls the control device on the ground station side. and an on-vehicle station (not shown) on the unmanned forklift 7 side.

Reference numeral 17 denotes a travel distance detector attached to the forklift 7, and includes, for example, a slit plate 19 fixed to the rotating shaft 18a of a travel motor 18 that drives an axle.
and a detection section 20 that detects the slits in the slit plate 19 and generates a pulse signal S1 proportional to the traveling distance.

21 is a stop coil fixed to the lower surface of the mast 8, and when it corresponds to the stop cable 6, it outputs a stop signal and stops the forklift 7 at a position corresponding to the first cargo storage position P1. It's getting old. 22 is a forward distance sensor as a light emitting/receiving type forward detector attached to the tip of the fork 10, and is a distance D between the tip of the fork 10 and the load W.
An output voltage proportional to a change in is output as a distance signal S2.

Reference numeral 23 in FIG. 4 is a comparator, which outputs an operation signal S3 when the distance signal S2 of the front distance sensor 22 reaches a certain level (that is, when the fork tip approaches a certain distance with respect to the cargo W). ing. 24 is a counter which counts the output pulse signal S1 of the mileage sensor 17 and outputs a mileage signal S5.

Reference numeral 25 denotes a control device consisting of a microcomputer, etc., and a memory circuit of the control device 25 stores a second command coil 4 necessary for shifting the attitude of the forklift 7 to a completely parallel state with the cargo handling guidance cable 3. A travel distance L1 after passing through is stored as a memory M1, and a travel distance L2 necessary for the forklift 7, which has stopped tilting on the cargo handling guide cable 3, to move backward and correct its attitude, is stored as a memory M2. This control device 25 outputs a reset signal S4 for the counter 24 when the forklift passes the second command coil 4, thereby resetting the counter 24. Then, the forklift moves forward and the forward distance signal S3 is output from the comparator 23.
When is output, mileage signal S5>Memory M
If it is 1, continue the cargo handling operation, S5<M1
In this case, a reset signal S4 for the counter 24 and a backward movement signal S8 are output. Furthermore, when the forklift moves backward and S5=M2, a stop signal S6 is outputted, followed by a forward signal S7, so that the cargo handling operation can be continued.

Next, a method for controlling the posture of a forklift will be explained based on the unmanned forklift cargo handling system configured as described above.

Now, in order to place the first cargo at the first cargo storage position P1 among the cargo storage positions P1 to P3 in FIG.
When the forklift 7 moves forward while being unmannedly guided along the travel guidance cable 1 and the communication device 14 corresponds to the first command coil 2, communication is performed between the two, and the forklift 7 travels by a cable selection control circuit (not shown). The guidance signal of the guidance cable 1 is released and the guidance signal is applied to the corner traveling guidance cable 5, so that the forklift 7 is guided to turn along the corner running guidance cable 5. Then, when the forelift 7 moves onto the cargo handling guidance cable 3 as shown by the chain line in FIG. 1 and the communication device 14 corresponds to the second command coil 4,
Communication takes place between the two, a reset signal S4 is output from the control device 25, and the counter is reset. Then, the traveling distance L of the forklift 7 from the second command coil 4 is measured.

Even if the forklift 7 moves forward and the traveling distance L becomes a constant distance L1, and the traveling distance signal S5 becomes larger than the memory M1, since there is no load in the loading positions P1 to P3, the distance signal from the forward distance sensor 22 S
2 does not become less than a certain value, therefore, the operation signal S3 is not output from the comparator 23, and the forklift 7 is moved forward. And the stop coil 21
corresponds to the stop cable 6, the stop coil 2
1 outputs a stop signal and the forklift 7 stops running. Thereafter, cargo loading work is performed according to a command from the control device 25, and the cargo W on the fork 10 is
1 is placed at cargo storage position P1.

After the first load W1 is placed at the cargo storage position P1, a plurality of loads are weighted and stacked on the top surface of this load W1, but at this time, the forklift 7 detects the presence of the load W1 by the front distance sensor 22. Therefore, the operation signal S3 is output from the comparator 23, and
The forklift 7 is stopped and loading work is performed.

Also, when placing a plurality of loads W2 at the second load storage position P2, the same procedure as the above-mentioned first load loading operation P1 is performed, but in this case, the lowermost load W2 When placing the load W1, the front distance sensor 22 detects the load W1, the forklift 7 is stopped, and the load W1 is placed.

Next, when placing the cargo W3 on the first stage of the third cargo storage position P3, it is the same as placing the cargo on the first stage of the second cargo storage position P2.

Furthermore, to explain the case where the cargo W3 is placed on the second or higher stage of the third cargo storage position P3, in this case, as shown in FIG. 5, when the distance signal S5 from the counter 24 is smaller than the memory M1, When the presence of the load W2 is confirmed by the forward distance sensor 22 and the distance signal S2 becomes below a certain value, the comparator 23 outputs the operation signal S3, and the control device 25 outputs the counter reset signal S4 and the backward movement signal S8. As a result, the forklift is moved backward along the cargo handling guide cable 3. and,
As shown in FIG. 6, the forklift 7 is moved backward a certain distance L2, and the travel distance signal S5 is stored in the memory M2.
When it becomes the same, the control device 25 issues a stop signal S6.
is output and the forklift 7 is stopped, and then a forward movement signal S7 is output and the forklift 7 is moved forward.

Further, when the forklift 7 is moved forward and the distance signal S2 from the front distance sensor 22 becomes below a certain value, the comparator 23 outputs the operation signal S3, the control device 25 outputs the stop signal S6, and the forklift 7 It was suspended, and since then, Fork 1
The load W3 on 0 is the load W3 at the third storage position P3
(Figure 7).

On the other hand, when picking up any cargo from the first to third tier of cargo at the cargo storage position P3, the traveling distance signal S5 is less than the memory M1, so the posture of the forklift is corrected as described above. .

In this way, cargo loading and unloading operations are carried out on the cargo handling guide cable 3, but in the embodiment of the present invention, the forklift 7 passes the second command coil 4 and moves forward a certain distance L1 before the forklift 7
When the distance signal S2 falls below a certain value due to a load in front of the forklift 7, the forklift 7 is moved backward and moved forward again.
It is possible to move the cargo to the proper cargo storage (pick-up) position and place the cargo stably, and it is also possible to smoothly pick up the cargo and improve safety.

As described in detail above, the present invention provides a posture control method for an unmanned forklift that is guided to turn from a travel guidance cable to a cargo handling guidance cable, then travels unmanned along the cargo handling guidance cable and performs cargo handling work at a cargo loading position. , the forward travel distance of the unmanned forklift from the command coil position is measured based on a command signal from a command coil disposed on the cargo handling guidance cable near the traveling guidance cable, and then,
A forward detector installed on the unmanned forklift determines whether the forward traveling distance reaches a certain distance required for the unmanned forklift to become approximately parallel to the cargo handling guidance cable after passing the command coil position. When it is confirmed that the unmanned forklift is close to the cargo storage position, the unmanned forklift is moved backward from that position by a predetermined distance necessary for attitude correction, and then moved forward to the cargo storage position again. , the posture of the unmanned forklift that has been swivel-guided to the cargo-handling guidance cable can be made to be almost parallel to the cargo-handling guidance cable before the forklift stops at the loading position. This has the effect of controlling the posture and then moving it to the normal stopping position, allowing cargo handling work to be carried out safely.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of an unmanned forklift cargo handling system used in the present invention, FIG. 2 is an enlarged side view of the unmanned forklift, and FIG. 3 is a schematic bottom view of the unmanned forklift. FIG. 4 is an attitude control circuit diagram of the unmanned forklift, and FIGS. 5 to 7 are plan views for explaining the attitude control operation of the unmanned forklift. Traveling guidance cable...1, Cargo handling guidance cable...
...3. Second command coil...4. Unmanned forklift...7. Communicator...14. Mileage sensor...
17. Front distance sensor as a front detector...2
2, Comparator...23, Counter...24,
Control device...25.

Claims (1)

[Scope of Claims] 1. In the attitude control method of an unmanned forklift, which is guided to turn from a travel guidance cable to a cargo handling guidance cable, then travels unmanned along the cargo handling guidance cable and performs cargo handling work at a cargo storage position, comprising: The forward travel distance of the unmanned forklift from the command coil position is measured based on a command signal from a command coil disposed on the cargo handling guidance cable near the travel guidance cable, and then the forward travel distance is determined from the command coil position. A forward detector installed on the unmanned forklift indicates that the unmanned forklift is in the cargo loading position before the unmanned forklift reaches a certain distance required for the attitude of the unmanned forklift to become almost parallel to the cargo handling guidance cable. Attitude control of an unmanned forklift, wherein when it is confirmed that the forklift has approached, the unmanned forklift is moved backward from that position by a predetermined distance necessary for attitude correction, and then moved forward again to the cargo storage position. Method.