JPH0419126B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for controlling a stacker crane used for cargo handling work in an automated warehouse, and in particular to a method for controlling a fork device provided on an elevating body of a stacker crane. This invention relates to a stacker crane control method.

[Background of the invention]

As a cargo handling machine that performs cargo handling work in automated warehouses,
Statzker cranes are well known. Normally, a stacker crane runs on rails, lifts and lowers cargo loaded onto an elevating body to the target shelf, and uses a fork device attached to the elevating body to store the cargo on a designated shelf. Do this. On the other hand, a fork device is used to take out cargo stored on a shelf. In such work using a stacker crane, it is essential to move the crane to a predetermined position and stop it, and therefore, there is a problem that when the stacker crane is stopped, the elevating body loaded with cargo may sway. If the elevating body sways greatly during this stop (there is usually quite a large sway immediately after stopping), operating the fork device immediately will prevent problems such as the cargo falling or the cargo hitting the shelf structure. There is a high possibility that it will happen. Therefore, in order to carry out safe cargo handling operations, it is necessary to wait until the shaking has subsided before starting the fork operation. but,
Waiting for the vibrations to decay naturally after the vehicle stops will result in poor cargo handling efficiency.

For this reason, various anti-sway devices for forcibly attenuating the sway of the elevating body have been devised. That is, there are those that use electromagnets and those that damp vibration using a hydraulic mechanism. Examples of these techniques include Publications No. 49-10624 and Publication No. 10624,
The one disclosed in Japanese Patent No. 52-3267 is known.

Now, in conventional devices of this type, the vibration damping device was operated simultaneously with the braking action of the stacker crane. However, no matter how much the damping device is operated, there is considerable shaking when the vehicle is stopped, and the fork device cannot be operated immediately after the vehicle is stopped. In other words, it must last for a certain period of time determined by the ability of the vibration damping device.
Therefore, the current situation is that the fork device waits for a certain period of time after it is stopped before operating the fork device.

[Purpose of the invention]

An object of the present invention is to improve cargo handling efficiency without using a vibration damping device, that is, to do so at low cost.

[Summary of the invention]

The present invention was made based on the fact that cargo handling efficiency is determined by the amount of swing of the fork device.

The present invention is characterized in that the amount of sway of the fork device is determined after stopping the stacker crane, and the fork device is operated under the condition that the amount of sway is less than or equal to the allowable amount of sway.

According to this, the fork device is immediately operated under the condition that the amount of sway in the position of the fork device is equal to or less than the allowable amount of sway, so that the cargo handling efficiency of the stacker crane is improved.

The amount of sway of the fork device is determined by the height position of the fork device (i.e., the elevating body) and the weight of the load on the fork device, so if the height is low, the amount of sway will be small, so the height of the fork device is determined by the weight of the load on the fork device. The fork device can be operated immediately after the vehicle stops running. The lower the height position and the smaller the weight of the load, the shorter the time from stop to operation of the fork device.

Therefore, cargo handling efficiency can be improved at low cost without using a vibration damping device.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail based on specific embodiments shown in the drawings. Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the state of the stacker crane when it is stopped, Fig. 3 is a diagram showing the configuration of the stacker crane, and Fig. 4 is a diagram showing the state when the stacker crane is stopped. FIG. 6 is a diagram showing the relationship between the rocking characteristics and the operation start time of the fork device.

First, the overall structure of the stacker crane will be explained with reference to FIG. 1 is a three-dimensional warehouse shelf, and 2 and 3 are the upper and lower guide rails of the stacker crane.
4 is a Statzker crane, 5 is a traveling device for running the Statzker crane, 6a is a trolley, 6
b is the structure, and 7a and 7b are support columns. 8 is an elevating body, 11 is a fork device provided on the elevating body 8, 12 is a rope for elevating the elevating body 8, and 13 is an elevating device that raises and lowers the elevating body 8 by hoisting and lowering the elevating rope 12. Reference numeral 14 denotes an on-board control device that outputs control commands for running, lifting and lowering, fork operation, etc. of the stacker crane. 15 is a lower travel detector, and 17 is an upper travel detector. 16
is an elevation detection device for detecting the elevation speed of the elevating body 8. 18a to 18c are running wheels, and in this example, only 18a is driven by the running device 5. 19 is a guide roller. 9 indicates a shelf, and 10 indicates a cargo.

Next, an embodiment of the present invention for controlling a stacker crane as shown in FIG. 3 will be described with reference to FIG. In FIG. 1, a calculation device 21 outputs a speed setting voltage V according to a speed pattern as a command signal. As a result, the voltage/frequency conversion circuit (V/circuit) 22 outputs the operating frequency and supplies this to the inverter circuit 27 via the adder 24. Thereby, the inverter circuit 27 generates electric power according to the operating frequency, and drives the drive motor 51 of the traveling device 5. As a result, running wheel 1
8a receives rotational driving force through the gear 52, and the stacker crane 4 travels. Traveling detector 1
5 and 17 respectively detect the running speeds x ₁ and x ₂ , which are then converted to the running distance via integration circuits 28 and 29.
Obtain x ₁ and x ₂ . Similarly, by the elevation detector 16,
The elevating speed l of the elevating body 8 is detected, and this is passed through the integrating circuit 30 to obtain the elevating position l of the elevating body 8. These detected physical quantities are provided to the arithmetic unit 21. In addition, the output x ₁ of the running detector 15 is sent to the adder 23
The difference is given to the proportional control circuit 25, and the correction frequency Δ is calculated via the limiter 26. This△
is applied to an inverter circuit 27 via an adder 24, forming a feedback speed control system.

FIG. 2 shows the situation when the Statzker crane is stopped, with the dotted line showing the maximum amplitude shaking state and the solid line showing the state where the shaking has subsided. In the figure, x ₁ and x ₂ indicate the travel distance from the origin or deceleration start point to the stop point. When the shaking has subsided, x ₁ and x ₂ have the same value, but as long as the shaking continues, x ₂ changes over time. Similarly, x ₃ is the travel distance from the origin or deceleration start point to the stop point. This x ₃ itself was not measured. 1 is the elevation position of the elevating body 8. The swing angle θ of the Statzker crane when stopped is expressed by the following formula.

θ＝t _ao ^-1 x ₁ − x ₂ / l ₀ ...(1) However, l ₀ is the height when the elevating body 8 rises to the maximum height position or the height of the pillar of the Statzker crane .

The swing width δ of the elevating body 8 located at a height l from the bottom of the stacker crane is determined by the following equation.

δ=l・t _ao θ=l・(x ₁ − x ₂ )/l ₀ ...(2) Next, the first
The operation of the diagram will be explained. The stacker crane moves toward a target position in response to an operation command. During movement, the speed of the Statzker crane is controlled while detecting the running state quantities (traveling distance x ₁ , x ₂ , traveling speed x ₁ , x ₂ , lifting position l, etc.) of the Statzker crane 4 . The oscillation width δ is calculated sequentially, and oscillation prevention control is also performed separately. Then, upon reaching the target position, the Statzker crane is stopped. Swing width δ after reaching the target position and stopping
is calculated by the calculation device 21 and compared with the permissible swing width δ _p as shown in the following equation.

|δ|≦δ _p ...(3) Then, the vibration amplitude δ detected by the calculation is (3)
When the condition of the formula is satisfied, the arithmetic unit 21 gives a fork drive command to the fork drive device 111 of the fork device 11, and causes the fork 112 to operate. FIG. 4 illustrates the above-mentioned judgment in the arithmetic unit 21 and the timing of starting the operation of the fork device. Driving of the fork device is started at time _t2 when the vibration δ shown by the broken line in FIG. 4 falls within the permissible range. When the elevating body is at the highest position, its sway is δ _nax , and in this case the sway is δ
The timing at which is within the permissible range is at time t ₁ . Note that the reference times of t ₂ and t ₁ are the times when the stacker crane stops.

According to the embodiment described above, the amount of sway (width) δ of the elevating body after it stops traveling is detected in real time, and the fork device is activated when this falls within the allowable range, thereby eliminating unnecessary long waiting times. There is no longer a need to operate the system after hours, and cargo handling efficiency is greatly improved. Furthermore, since the actual shaking width δ is detected, there is no problem of the fork device operating after a certain period of time even if the shaking does not subside due to some inconvenience, which improves safety. Note that the determination as to whether or not it is within the allowable range is actually made by comparing average values within a certain predetermined time period, or by comparing integrated values of the amount of shaking within a predetermined time period.

Now, in the above-described embodiment, although the amount of sway δ was determined based on the difference between the vertical travel distance and the vertical position of the elevating body, the present invention is not limited thereto. That is, it is sufficient that the amount of vibration δ is determined directly or indirectly using some kind of detection means, and the drive of the fork device is started when this amount δ becomes less than the allowable amount. The amount of sway δ can also be determined using the outputs of the sway angle detector and the elevation position detector.
In FIG. 1, the arithmetic device 21 or most of the other components including the arithmetic device 21 can be realized by a general-purpose microcomputer 210.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to improve the cargo handling efficiency of a stacker crane without using a vibration damping device, that is, with an inexpensive configuration.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram for explaining the state when the stacker crane is stopped, Fig. 3 is a diagram showing an example of the stacker crane, and Fig. 4 is a diagram showing the shaking. FIG. 3 is a diagram showing the relationship between the time of operation of the fork device and the operation start time of the fork device. 4... Statzker crane, 5... Traveling device,
8...Elevating body, 11...Fork device, 15,1
7... Traveling detector, 16... Lifting detector, 21...
... Arithmetic device, 22 ... Voltage/frequency conversion circuit, 2
3, 24... Adder, 25... Proportional control circuit, 2
6... limiter, 27... inverter circuit.

Claims (1)

[Claims] 1. When the computing device detects that the moving Statzker crane has stopped at the target position, the computing device immediately uses the value of the detection means installed on the Statzker crane to determine the position of the Statzker crane's elevating body at the vertical position. The amount of sway in the moving direction of the crane is determined, and then the calculation device determines whether the determined amount of sway is smaller than the allowable amount of sway, and the calculation device determines whether the amount of sway determined is the permissible amount of sway. If the amount of shaking is smaller than the allowable amount of shaking, the fork device of the elevator is commanded to operate, and if the amount of shaking determined is larger than the allowable amount of shaking, the amount of shaking is determined again, and the amount of shaking determined is smaller than the allowable amount of shaking. A method for controlling a stacker crane, characterized in that the operation of a fork device is commanded at a certain point in time.