JPH07187320A - Speed control device for stacker crane - Google Patents

Abstract

PURPOSE:To travel at stable speed even if a load change is caused, and smoothly stop a stacker crane in a prescribed position without using a brake. CONSTITUTION:A speed control device for a stacker crane is composed of an AC servomotor 7 to drive a driving wheel of the stacker crane in rotation, a rotating speed detecting sensor 14 to detect rotating speed of this AC servomotor 7, a controller 10 to output a rotating speed signal according to traveling speed of the stacker crane 1, a motor driver 13 to perform current-carrying control according to this rotating speed signal and a comparing operation circuit 11 to correct the current-carrying control to the motor driver 13 according to actual rotating speed detected by the rotating speed detecting sensor 14. Even if a load change is caused, the AC servomotor 7 is made drivable at stable rotational speed, and deceleration control is made possible until the AC servomotor 7 stops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling the traveling speed of a stacker crane used in an automatic warehouse.

[0002]

2. Description of the Related Art In an automatic warehouse, shelves are installed along a traveling direction of a stacker crane, and the stacker crane travels to store or take out luggage on a predetermined shelf. The stacker crane includes drive wheels that are driven to rotate by an electric motor, and the traveling speed is controlled by controlling the rotation of the electric motor by a motor driver using a controller, a control circuit, and an inverter.

[0003]

In such a traveling speed control device, the rotation speed of the electric motor may differ depending on the load acting on the electric motor, and the weight of the luggage stored and taken out by the stacker crane changes. In this case, the traveling speed of the stacker crane may be different from the steady speed, and malfunction may occur during automatic control.

Further, in the conventional speed control using the inverter, the output torque of the electric motor is small in the low frequency region, so that the output torque of the electric motor is small and difficult to control when the stacker crane starts or stops traveling. .
In particular, when the stacker crane is stopped, the electric motor cannot be controlled until it stops rotating, so the stacker crane is stopped by controlling the brake.
The stacker crane is decelerated to a sudden decrease as the deceleration curve indicated by the dotted line. As a result, it causes the stacker crane to swing.

Therefore, an object of the present invention is to provide a speed control device for a stacker crane, which can solve the above-mentioned problems.

[0006]

An AC servomotor 7 for rotatably driving a drive wheel 6 of a stacker crane 1 and this AC
Rotation speed detection sensor 1 for detecting the rotation speed of the servo motor 7
4, a controller 10 that outputs a rotation speed signal based on the traveling speed of the stacker crane 1, a motor driver 13 that controls energization according to the rotation speed signal, and an actual rotation speed detected by the rotation speed detection sensor 14. A speed control device for a stacker crane, which comprises means for correcting the energization control to the motor driver 13 based on the above.

[0007]

[Operation] There is no speed change when the stacker crane 1 changes in load, and no malfunction occurs when the stacker crane 1 is automatically controlled. Even when the traveling speed of the stacker crane 1 is extremely low, the output torque is stable and easy to control. Therefore, the stacker crane 1 can be smoothly stopped at a predetermined position by decelerating until the AC servomotor 7 is stopped without using a brake. Swinging when the stacker crane stops can be reduced.

[0008]

[Example] As shown in Fig. 2, stacker crane 1
Mounts a mast 3 on the traveling body 2, and an elevating body 4 which moves up and down along the mast 3 is provided with a loading fork 5 so as to be reciprocally movable. Driving wheels 6 of the traveling body 2 are driven by an AC servomotor 7. By doing so, the vehicle runs along the rails 8, and the shelves 9 are installed along the rails 8 to form an automated warehouse.

As shown in FIG. 3, a controller 10, a comparison operation circuit 11, a control circuit 12, and a motor driver 13 are provided.
The rotational speed of the AC servomotor 7 is detected by a rotational speed detection sensor 14 such as an encoder and fed back to the comparison calculation circuit 11.

Next, the speed control operation will be described. The controller 10 outputs a preset rotation speed signal by inputting a running start signal and a stop signal, and the rotation speed signal is input to the control circuit 12 via the comparison operation circuit 11, and the control circuit 12 is input. Based on the signal, a control signal is output to the motor driver 13 to energize the AC servo motor 7 to drive it to rotate. The actual rotation speed of the AC servo motor 7 is detected by the rotation speed detection sensor 14, and the detected actual rotation speed is compared with the rotation speed signal output from the controller 10 by being input to the comparison calculation circuit 11 to obtain both. Correct so that they match. As a result, the AC servomotor 7 is rotationally driven at a rotational speed preset by the controller 10.

Because of this, the stacker crane 1
Even if the weight of the load on the loading fork 5 changes and the load acting on the AC servomotor 7 changes, the rotation speed reaches the set value, and the stacker crane can travel at a stable speed.

Further, since the AC servomotor 7 can output a torque of 100% or more even in a low frequency region, it is possible to control the rotation of the stacker crane 1 until it stops rotating,
The deceleration curve at that time draws a smooth curve as shown by the solid line in FIG. 1, the stacker crane can be stopped at a predetermined position without using a brake, and the swing of the stacker crane can be reduced.

[0013]

The speed of the stacker crane 1 does not change when the load of the stacker crane 1 changes, and no malfunction occurs when the stacker crane 1 is automatically controlled. Even when the traveling speed of the stacker crane 1 is extremely low, the output torque is stable and easy to control. Therefore, the stacker crane 1 can be smoothly stopped at a predetermined position by decelerating until the AC servomotor 7 is stopped without using a brake. Swinging when the stacker crane stops can be reduced.

[Brief description of drawings]

FIG. 1 is a chart showing a deceleration curve of a motor.

FIG. 2 is a schematic explanatory diagram of an automated warehouse.

FIG. 3 is an explanatory diagram of a speed control device according to the present invention.

[Explanation of symbols]

1 ... Stacker crane, 7 ... AC servo motor, 10 ...
Controller, 11 ... Comparison arithmetic circuit, 12 ... Control circuit,
13 ... Motor driver, 14 ... Rotation speed detection sensor.

Claims (2)

[Claims] 1. An AC servomotor 7 for rotationally driving drive wheels 6 of a stacker crane 1, and this AC servomotor 7
Rotation speed detection sensor 14 that detects the rotation speed of the stacker crane 1, a controller 10 that outputs a rotation speed signal based on the traveling speed of the stacker crane 1, a motor driver 13 that controls energization according to the rotation speed signal, and the rotation speed. Detection sensor 1
4. A speed control device for a stacker crane, comprising: means for correcting the energization control to the motor driver 13 based on the actual rotation speed detected in 4. 2. When stopping the stacker crane 1, A
The speed control device for a stacker crane according to claim 1, wherein deceleration control is performed until the C servo motor 7 is stopped.