JPH0733210A - Drive control device of stacker crane - Google Patents

Abstract

PURPOSE:To aim at improvement in operating cycle time while maintaining safety and accuracy by memorizing creep data by each travel and performing drive control upon reading the creep data appropriate to the planned travel at the time of traveling. CONSTITUTION:A control/calculation unit 8 reads the creep data appropriate to a distance of travel intended to make at the time of travel, from a ROM 9 which memorizes the creep data by each travel. The creep data, which is composed of a travel mutually adding an over shoot travel and an under shoot travel which occur by each travel and there is an addition creep data, which is the case when the over shoot travel is more than the under shoot travel, and a subtraction travel, which is the case when the under shoot is more than the over shoot travel. The control/calculation unit 8 calculates the creep travel by creep data read and makes a travel on the basis of the creep travel found. Thus any travel may make it possible to travel about a fixed creep travel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for controlling the drive of a stacker crane provided in an automatic warehouse, and more particularly to a drive control of a stacker crane for ensuring safety and accuracy and improving operation efficiency. Regarding the device.

[0002]

2. Description of the Related Art In order to temporarily store products and workpieces,
Two racks having a plurality of racks arranged in a matrix,
An automated warehouse consisting of a stacker crane that travels up and down between two racks to transport articles is used. Figure 4
As shown in Fig. 1, the stacker crane mainly consists of rail 1,
2 is provided with a traveling carriage 4 that travels between the racks along with 2, and an elevating stand 3 that ascends and descends along two masts 5 and 6 that are erected on the traveling carriage 4. Articles are delivered to and from the shelves and stations by the slide fork 7.

The traveling of the traveling carriage 4 of the stacker crane and the raising and lowering of the lifting platform 3 are controlled according to so-called triangular control. FIG. 5 is a diagram showing a time-speed relationship in traveling of the traveling vehicle. As shown in this figure, the traveling vehicle accelerates at a constant acceleration, travels at a high speed VH, and reaches a low speed VL at a constant acceleration. Slow down and stop at the destination. The distance traveled at the low speed VL immediately before the stop at the destination is detected is called the creep distance Cr.

[0004]

The drive control device for controlling the stacker crane controls the driver for driving the traveling motor so that the linear time-speed relationship shown by the triangular control in FIG. 5 is obtained. However, the actual speed of the traveling carriage is not linear, and a deviation occurs. That is, during acceleration, it is not possible to follow the assumed acceleration and undershoot mainly occurs in the motor output, and overshoot occurs when shifting to high speed VH and during deceleration.

When the undershoot distance U is larger than the overshoot distance O as shown in FIG. 5, the distance becomes insufficient by subtracting the overshoot distance O from the undershoot distance U, so the creep distance running at low speed VL. Cr becomes larger accordingly. Therefore, it takes a lot of time from the start of traveling to the stop, and the cycle time increases. On the contrary, especially when the traveling speed is high V as shown in FIG.
In the case of a short distance movement that does not reach H, the overshoot distance O becomes larger than the undershoot distance U. If there is a large difference between the overshoot distance O and the undershoot distance U, the vehicle will reach the destination point while decelerating to the low speed VL, causing a sudden stop from a speed higher than the speed at which the vehicle normally stops. Occasionally, there was an accident such as a load collapse, or there was an overrun.

Therefore, an object of the present invention is to provide a drive control device for a stacker crane which can improve the operation cycle time while ensuring safety and accuracy.

[0007]

In order to achieve the above object, the present invention provides a storage means for storing creep data for each moving distance, and a creep corresponding to the moving distance to be moved when moving. The drive control device of the stacker crane is configured by including the data read from the storage means to calculate the creep distance and the drive control means for moving based on the obtained creep distance.

[0008]

Since the present invention has the above-mentioned structure, it has the following effects.

According to the drive control device for the stacker crane of the present invention, the drive control means reads the creep data corresponding to the moving distance to be moved from the storage means during the movement. The storage unit stores the creep data for each moving distance. The creep data consists of the sum of the overshoot distance and the undershoot distance that occur for each movement distance, and the additional creep data and the undershoot distance when the overshoot distance is greater than the undershoot distance. There is subtraction creep data when it is larger than the overshoot distance.
The drive control means calculates the creep distance from the read creep data, and moves based on the calculated creep distance. That is, the drive control means controls the drive so that when the moving distance is the additional creep data, the creep distance is increased by adding the creep distance, and when the moving distance is the subtractive creep data, the creep distance is shortened accordingly. As a result, it is possible to move with a substantially constant creep distance at any moving distance.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments shown in the drawings will be described below.

FIG. 1 is a block diagram showing the main part of the configuration of an embodiment of a drive control device for a stacker crane according to the present invention.

In FIG. 1, the drive control device for controlling the operation of the stacker crane as shown in FIG. 4 comprises a control / arithmetic unit 8 and a ROM 9 storing creep data. The control / arithmetic unit 8 controls the inverters 10 and 11 to drive the lifting motor 12 and the traveling motor 13. control·
The transport command to the calculation unit 8 is transmitted from the operation unit 14.

The transfer command issued from the operation unit 14 is one shelf or a shipping station as a starting point and a receiving station or one shelf as an ending point. control·
The calculation unit 8 calculates the lifting motor 12 from the distance between the start point and the end point,
Compute the process of the change in speed that drives the traveling motor 13,
The inverters 10 and 11 are controlled according to the result.

Creep data is stored in the ROM 9 in the form of a data table. That is, the addition creep data Cr _add or the subtraction creep data Cr _sub corresponding to each moving distance is stored for each table number. These creep data are actually pulse values of the pulse generator that measures the moving distance.

First, the control / calculation unit 8 converts the number of stations to be moved (in the case of the traveling carriage 4; the number of steps in the case of the lifting table 3) into a movement distance. The table number is obtained by dividing the moving distance by the set pitch. The reason that the distance is not the number of stations or the number of steps but the movement distance is to enable one program to support automatic warehouses having various layouts. The creep data is a value actually measured by actually performing a test operation of the traveling vehicle 4 and the lifting platform 3 of the stacker crane.

Next, the creep data corresponding to the moving distance is read from the ROM 9 and the creep distance is calculated.
The creep distance Cr ^* is obtained by the sum of the reference creep distance Cr and the creep data. That is, Cr ^* = Cr + Cr _add Cr ^* = Cr-Cr _sub is calculated, and the obtained creep distance Cr ^* is set as the set creep distance when actually driving.

First, the case where the data corresponding to the moving distance is the subtractive creep distance Cr _sub will be described with reference to 2. In this case, since the undershoot distance U is larger than the overshoot distance O, the creep distance becomes too long as shown in FIG. 5 without correction. Therefore, the creep distance Cr ^* obtained by subtracting the subtractive creep distance Cr _sub from the reference creep distance Cr is set, and traveling drive is performed using this.

The control / calculation unit 8 sets the low speed VL at a distance obtained by subtracting the creep distance Cr ^* from the moving distance.
Calculate the motor command value for triangular control. The process of change of the moving speed calculated by the control / calculation unit 8 is a linear speed-time of accelerating to a high speed VH at a constant acceleration, traveling at a high speed VH, and decelerating to a low speed VL at a constant acceleration. Get involved.

When the traveling vehicle 4 is driven by the obtained motor command value, undershoot and overshoot actually occur in the motor speed output, and a curvilinear speed change occurs. In this case, since the undershoot distance U is larger than the overshoot distance O, when the vehicle is decelerated to the low speed VL, the traveling vehicle 4 is in front of the scheduled point by the subtractive creep distance Cr _sub . Therefore, as a result, the traveling vehicle 4 travels at the low speed VL for the reference creep distance Cr, which is the sum of the creep distance Cr ^* and the subtractive creep distance Cr _sub, and stops at the destination point.

On the contrary, in the case of the additive creep distance Cr _add ,
Since the overshoot distance O is larger than the undershoot distance U, the creep distance disappears as shown in FIG. 6 without correction, and overrun and load collapse occur.
The calculation unit 8 adds the creep distance C to the reference creep distance Cr.
The creep distance Cr ^*, which is obtained by adding _radd , is set, and the motor command value is calculated so that the low speed VL is obtained by subtracting the creep distance Cr ^* from the moving distance. Then, since reaching the low speed BL starts deceleration from the front by adding the creep distance Cr _{the add} compared to linear velocity changes obtained by computation as shown, over due to the deviation of only caused the drive control summing creep distance Cr _{the add} The run can be corrected, and as a result, the distance traveled at the low speed VL becomes the reference creep distance Cr.

As described above, according to the drive control device for the stacker crane according to this embodiment, the creep distance can be kept constant regardless of the moving distance in which the overshoot and the undershoot change. It is possible to prevent a long running time at the low speed VL, which adversely affects the cycle time, and an overrun or a load collapse due to an abrupt stop from a relatively high speed.

The embodiment of the present invention has been described above.
It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be appropriately modified within the scope of the gist of the present invention.

[0023]

As described above, according to the drive control device for the stacker crane of the present invention, the creep distance can be kept constant without being affected by the overshoot and the undershoot which vary depending on the moving distance. It is possible to prevent a long running time at low speed from increasing the operation cycle time, and it is possible to prevent an accident such as an overrun or a load collapse caused by stopping at a speed higher than the low speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of an embodiment of a drive control device for a stacker crane according to the present invention.

FIG. 2 is a diagram showing a change in speed-time in the case of subtractive creep data of a traveling carriage of a stacker crane driven by the embodiment of FIG.

FIG. 3 is a diagram showing a change in speed-time in the case of additive creep data of a traveling vehicle of a stacker crane driven by the embodiment of FIG.

FIG. 4 is a perspective view showing an example of a stacker crane to which the embodiment of FIG. 1 can be applied.

FIG. 5 is a diagram showing a change in speed-time of a traveling carriage by a drive control device for a conventional stacker crane.

FIG. 6 is a diagram showing a change of speed-time of a traveling carriage by a drive control device of a conventional stacker crane.

[Explanation of symbols]

Cr Standard creep distance Cr ^* Creep distance Cr _sub Subtractive creep distance U Undershoot distance O Overshoot distance VH High speed VL Low speed

Claims (1)

[Claims] 1. A storage means for storing creep data for each moving distance, and a creep distance corresponding to a moving distance to be moved is read from the storing means at the time of moving to calculate and calculate the creep distance. A drive control device for a stacker crane, comprising: a drive control unit that moves based on a creep distance.