JPH048325B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to load transfer means used in automated warehouses between a traveling crane for loading and unloading and shelves or loading docks for handling loads, or various conveyance devices. The present invention relates to a method for controlling the movement of a running fork, which is used as a means for transferring loads between vehicles.

(Prior art and its problems) The fork for transferring loads as described above can move forward to the left or right side to the limit position with the center position as the home position. When driving, that is, when moving forward from the center position to either the right or left limit position, or when moving backward from the limit position to the center position, in order to perform each stroke efficiently, the movement should be as close to the stroke limit as possible. It must be controlled so that it moves at high speed, then decelerates to low speed and stops safely.

Conventionally, the current position of the fork is detected by counting the emitted pulses of a pulse encoder that is linked to the movement of the fork, and a pulse count value of the deceleration position determined in advance by learning is set, and this pulse count value and the fork are The conventional method relied on a so-called pulse encoder method, which controls deceleration when the pulse count value corresponding to the current position becomes equal to the pulse count value, but in this conventional method, the pulse encoder and accompanying mechanical and electrical components were used. Not only is the cost high because of the necessity, but it is also difficult to incorporate these parts into a load transfer device that has little space.

(Means for solving the problem) From the start of the movement, move the load transfer fork, which can move in and out left and right from the center position, from one end position to the other end position at high speed Hv. Measure the time T1 required to reach the center position, and after reaching the center position, decelerate to low speed Lv, continue moving at low speed Lv for a certain period of time, then stop, and then move the fork backwards at low speed Lv. In addition to measuring the time T2 required to move and reach the center position again, the speed ratio of low speed Lv to high speed Hv
The time T3 is calculated by multiplying the time T2 by Lv/Hv, and when the fork is in actual operation, after the fork starts moving in and out,
Move at high speed Hv for time T1−T3 and then move at low speed
The point is to decelerate to Lv and stop at the limit position or the center position.

(Embodiment) An embodiment of the present invention will be described below based on the attached illustrative drawings. In FIG. ，
3 and a traveling path 6 located between the cargo handling platforms 4 and 5. This crane 1 is equipped with an elevating carriage equipped with a load transfer fork 7 that can move forward to either the left or right to transfer loads between the left and right shelves 2 and 3 and the left and right loading platforms 4 and 5. 8 is provided.

As shown in FIG. 2, the fork 7 is a conventional fork that is composed of a secondary fork 7a supported on a fixed fork (not shown) and a primary fork 7b supported on the secondary fork 7a. A cam 9 is attached to the lower part of the secondary fork 7a in parallel with the direction of movement of the secondary fork 7a. A right extension detection switch 10 and a left extension detection switch 11 which are turned OFF, and a left and right extension detection switch 12 which is turned ON by contacting the center position of the cam 9 are arranged in the elevating carriage 8. When the fork 7 (secondary fork 7a and primary fork 7b) advances from this central position to the left and right exit limit positions (the imaginary line in Figure 2 shows the state in which it advances to the right exit limit position), the right exit is detected. Of the switch 10 and the left exit detection switch 11, the detection switch on the advancing direction side is turned on, and the left and right exit limit detection switch 12 is turned off.

The calculation/storage/control means 13 shown in FIG. 2 is composed of a microcomputer and associated equipment, and includes the detection switch 10,
11, the detection signal 12a of the left and right output limit detection switch 12, which is inverted from ON to OFF by the NOT gate 14, and the right output detection signal 10a are input. Right output limit detection signal 15a from AND gate 15,
A left output limit detection signal 16a from an AND gate 16 which receives as input the detection signal 12a of the left and right output limit detection switch 12 via the NOT gate 14 and the left output middle detection signal 11a, and a clock pulse supplied from the clock pulse generating means. 17, speed command value 18, and drive device 1 for driving the fork 7 in and out
The current speed value 20 from 9 and the like are input, and a necessary control signal 21 is outputted to the fork ejection/retraction drive device 19 based on these inputs.

In addition, as the moving speed of the fork 7, high speed and low speed values are set in advance in the calculation/storage/control means 13 by the speed command value 18,
Further, an acceleration pattern in which the vehicle accelerates to a predetermined high speed in a fixed time after starting, a deceleration pattern in which the vehicle decelerates from a high speed to a predetermined low speed in a fixed time, and a stop braking pattern to bring the vehicle to a complete stop from a low speed in a fixed time are also programmed in advance. Furthermore, the clock pulse 17 is transmitted at a rate of one pulse every 20 ms, for example, and is counted as a time count value.

[Learning method]

The learning work to be performed before using the fork 7 for actual load transfer work will be explained based on FIG.

(1) First, the fork 7 is advanced either to the left or right, for example, to the right, and stopped by outputting the right-extension limit detection signal 15a. As shown in FIG. 3A, the fork 7 is moved from this right extension limit position at high speed toward the left extension limit position on the opposite side. Of course, when starting, the vehicle is accelerated to a high speed in a certain period of time according to a predetermined acceleration pattern. Counting of the clock pulses 17 is started from the time when the fork 7 starts moving from the right extension limit position, and when the fork 7 reaches the center position, both the right exit detection signal 10a and the left exit detection signal 11a fall. Time count value T1 when
Measure and memorize.

(2) When the fork 7 reaches the center position, it decelerates from high speed to low speed, stabilizes the speed, and performs the next stop braking control safely and satisfactorily.The minimum necessary low speed movement time, e.g. 1s After moving at low speed for a while, the fork 7 is stopped. Of course, the deceleration to the low speed is also performed according to a predetermined deceleration pattern, and the predetermined low speed is reached in a certain period of time after the start of deceleration.

(3) Next, as shown in FIG. 3B, the fork 7, which has stopped at a position beyond the center position to the left, is again moved to the right at low speed, and at the same time as this movement starts, the clock pulse 17 is counted. start,
The time count value T2 when the fork 7 reaches the center position and both the right exit detection signal 10a and the left exit detection signal 11a fall is measured and stored, and the fork 7 is stopped at the center position. End the operation of Fork 7.

(4) Based on the preset low speed and high speed speed command values, calculate the speed ratio Lv/Hv of the low speed Lv to the high speed Hv, and multiply this by the time count value T2 to obtain the data T3 T3= In addition to finding T2·Lv/Hv, calculate and store the high-speed travel time T1-T3.

The above learning work is carried out by calculation, storage and control means 13.
This can be done automatically using a learning program stored in advance.

[Control method]

When carrying out actual load transfer work using the fork 7, for example, move the fork 7 from the right extension position to the center position.
As shown in FIG. 3C, which illustrates a case where the fork 7 is moved backward, counting of clock pulses 17 is started at the same time as the fork 7 starts, and the fork 7 is moved to a position where the time count value is equal to the high speed movement time T1-T3. If the fork 7 continues to move at high speed and decelerates to low speed when the time count value becomes equal to the high speed movement time T1 - T3, the fork 7 will be at the center position (center) when the preset low speed movement time of 1 s has elapsed. (When starting from the left and right starting positions)
By applying stop braking when both the right exit detection signal 10a and the left exit detection signal 11a fall (or when the left and right exit limit detection signals 15a or 16a rise). ,
The fork 7 can be stopped at the central position or at the left and right extension positions.

Of course, a predetermined control signal 2 is sent from the calculation/storage/control means 13 to the fork ejection/retraction drive device 19 at the required time.
1 is supplied, the fork 7 automatically moves in and out according to the above-described movement pattern.

(Operations and Effects of the Invention) As described above, according to the fork advancement/retraction drive control method of the present invention, the minimum required low-speed movement time can be secured after the fork starts to move in and out and before stopping;
In other words, after moving at high speed for the time T1 - T3 mentioned above, it is decelerated to low speed and stopped at the limit position or the center position, so the minimum necessary low speed movement is required before stopping, as in the case of the conventional pulse encoder method. By securing time, it is possible to safely stop the load transfer operation by moving the fork in and out while minimizing the cycle time of the load transfer operation.

Moreover, since the control is based on time, it can be easily implemented using the microcomputer and its attached equipment, which have traditionally been used to control forks. Since it is only necessary to use a detection means for detecting the left and right extreme positions, it can be implemented at a lower cost than when using a conventional pulse encoder method.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view of an automated warehouse, FIG. 2 is a block diagram illustrating the configuration of a control system, and FIG. 3 is a diagram illustrating a learning method and a control method during actual operation. 1... Traveling crane for loading and unloading, 7... Fork for loading and unloading, 7a... Secondary fork, 7b
...Primary fork, 9...Cam, 10~
12...Detector, 10a...Right out detection signal, 1
1a...Left-out middle detection signal, 13...Calculation/memory/
Control means, 14...NOT gate, 15, 16...
...AND gate, 15a...Right output limit detection signal, 1
6a... Left extension limit detection signal, 17... Clock pulse, 19... Fork extension/retraction drive device.

Claims (1)

[Claims] 1 Required time T1 from the start of movement until reaching the center position when a load transfer fork that can move in and out left and right from the center position is moved at high speed Hv from one end position to the other end position. After measuring and reaching the center position, the fork is decelerated to low speed Lv and continues to move at low speed Lv for a certain period of time, then stopped, and then the fork is moved backwards at low speed Lv until it reaches the center position again. In addition to measuring the required time T2, the speed ratio of low speed Lv to high speed Hv
The time T3 is calculated by multiplying the time T2 by Lv/Hv, and when the fork is in actual operation, after the fork starts moving in and out,
Move at high speed Hv for time T1−T3 and then move at low speed
A method for controlling the drive for a load transfer fork, which is characterized by decelerating to Lv and stopping at a limit position or a central position.