JPS6175704A - Method of and apparatus for controlling stacker crane - Google Patents

Abstract

PURPOSE:To improve loading efficiency by determining waiting time until a fork device is operated by detecting a parameter having an influence on rocking of a stacker crane prior to the time when the crane is stopped, and estimating a state of the rocking thereafter wit use of the parameter. CONSTITUTION:Upon controlling the operation of a stacker crane 1 adapted to move along a traveling rail 3 on a floor and a guide rail 4 on a ceiling surface, a computer first evaluates a speed pattern and controls a motor 10 for traveling the crane in accordance with the pattern. In addition, respective detectors 14, 15 detect elevated height of an elevator 7 of the stacker crane where it is stopped as well as the weight of a load 13, and estimates a state of rocking of the crane after said stoppage with use of those variable parameters. It further determines waiting time until the rocking state gets less than an allowable amount thereof for operating a fork device 8 disposed on the elevator immediately after the passage of said waiting time from the time of stoppage of the stacker crane 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method and *i for controlling a stacker crane used for cargo handling work in an automated warehouse.

[Background of the invention]

The stacker crane is well known as a loading machine that performs cargo handling work in automated warehouses.A typical stacker crane runs on rails and lifts and lowers the loaded cargo to the destination shelf. Then, the fork 5[1 provided on this elevating body performs the work of storing the cargo on the target shelf (this is called warehousing or warehousing work).

In addition, on the contrary, the cargo stored on the target shelf is transferred onto the elevating body using a fork device, and the stacker crane is run to carry it to the cargo exit (this is carried out at the warehouse or (referred to as work). For the above-mentioned loading and unloading work, the stacker crane has a traveling device consisting of a running wheel and a traveling motor that drives the second running wheel, an elevating am that raises and lowers the elevating body, and a fork device provided on the elevating body. has. The fork device is composed of four parts, such as a fork part such as a slide fork, and a fork motor that drives the fork part.

When loading and unloading operations using a stacker crane, it is essential to move to a predetermined position and float (hereinafter referred to as movement stop). Therefore, when the stacker crane is stopped, the stacker crane shakes and at the same time the elevating body shakes. There is.

Note that shaking here refers to shaking and swinging.

If this shaking is large when the vehicle is stopped, operating the fork device installed on the elevating body is likely to cause problems such as falling cargo or collisions in which the cargo or fork collides with the shelf structure. . 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 (operation of the fork device). Waiting for the sway to naturally attenuate after the piping is stopped will result in poor cargo handling efficiency.

For this reason, various anti-sway devices have been devised for forcibly damping the shaking of the stacker crane (strictly speaking, the shaking of the elevating body of the stacker crane). That is, there are those that use electromagnets and those that use mechanical brakes. As an example of such a technique, the one disclosed in Japanese Utility Model Publication No. 10624/1983 is known. In this publication, a pair of guide rollers that sandwich the guide rail by the elastic force of a spring and a brake device connected to the guide rollers are provided, and the brake device of the guide roller is activated at the same time as the brake device of the traveling device is activated. The technology has been disclosed.

Now, in a conventional device of this kind, a vibration damping device (sway stop device t) is operated simultaneously with the braking action (stopping operation) of the stacker crane. However, although the amount of shaking is reduced to some extent due to the operation of the vibration damping device,
Immediately after stopping, there is still considerable shaking, and the fork device cannot be operated immediately upon stopping. Therefore, the reality is that after stopping, the fork device is operated after a certain period of time. This so-called waiting time is usually set to a certain period of time using a timer or the like. This setting is generally done on the safe side by determining from empirical rules the time required until the attenuation of the shaking is almost completely gone, and then setting a timer to use this determined time as the waiting time.

[Purpose of the invention]

An object of the present invention is to provide a control method and apparatus for a stacker crane that can further improve the cargo handling efficiency of the stacker crane.

[Summary of the invention]

The present invention has demonstrated through experiments that the amount of sway of an elevating object and its damping characteristics vary significantly depending on changes in the speed pattern of the stacker crane, changes in the weight of the elevating object including the load, height and position of the elevating object, etc. The aim is to confirm this, take this into account, find the minimum waiting time until the fork device operates, and use this to perform the fork operation.

In other words, in case -B of the present invention, parameters that affect the shaking of the stacker crane are detected before the crane stops, and the detected parameters are used to estimate the shaking state after the crane stops, and the shaking The present invention is characterized in that the time required for the condition to become below the allowable amount of shaking is determined, and the fork device is operated immediately after the waiting time has elapsed since the stacker crane stopped.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

First, the outline Ra of the stacker crane in one embodiment of the present invention will be explained with reference to Figure @1. In this diagram,
The stanker crane 1 is installed between the traveling rail 3 and the guide rail 4, and travels along the shelf without being guided by the guide rail 4I on the traveling rail 3.

The shelf 2 is loaded with cargo 1 loaded by the stacker crane 1.
This is for storing 3. stacker crane 1
The frame is composed of a lower frame (saddle) 5, two posts 6, and an upper frame 18.

The elevating body 7 is suspended from this frame by a rope 11, and is moved up and down by replacing the rope 11. The fork device t8 is installed on the elevating body 7, and is actually composed of a slide fork and a motor for driving the fork.

Wheels 9a and 9b that are removably attached to the saddle 5 are
It is designed for running. A traveling device is constituted by the wheels 9a, 9b and a traveling motor 10 that rotationally drives the vehicle @9b. The elevating device 12 is for elevating and lowering the elevating body 7.

In this example, go up and down! ! 112 is the rope or wire 11 with one end attached to the elevating body 7! By taking it out and putting it back in, the elevating body 7 is caused to move up and down. Raise and lower! Specifically, f12 is composed of a drum and a motor for driving the drum. The detector 14 detects the weight of the load 130 loaded on the elevating body 7. The detector 15 is
This device is only for detecting the height (height and position) of the elevating body 7, and detects the height by detecting the object 16 provided on the post 6. Detected object 16 in this case
may be a mere sensed object, or may itself be something like a encoded code plate. Here, the sensing object includes a striker that can be mechanically sensed by a limit switch, a sensitive plate that can be sensed by a proximity switch, a photosensitive object that can be sensed by an optical switch, and the like. Note that the height of elevation of the elevating body 7 can also be obtained by measuring the amount of rope winding of the elevating device 12 using a pulse generator and a counter, so such a method may be used. Reference numeral 19 denotes a control panel in which a control device to be described later is stored. Control of traveling, lifting, fork operation, etc. is performed by a control device.

A detailed configuration example of a portion of this control device related to the present invention is shown in FIG. In FIG. 2, reference numeral 20 denotes a control calculation 81 (a general-purpose microcomputer can be used).

), and uses the input parameters to calculate and output a control signal for the stacker crane by a method described later. The input control unit 21 performs control for inputting warehousing/discharging commands from the host computer 30 and data regarding handled cargo via a transmission means or the like. In addition, the input control section 21
It also performs control for inputting detected values from a detector attached to the stuff car crane and control for inputting data from the data setting section 24.

The calculation unit 22 is a normal central processing unit (CPU),
In accordance with the program stored in the memory 25, each process of inputting data and outputting data is performed.

The output control unit 23 performs control to output a control signal that is the calculation result of the calculation unit 22 to each operating end (for example, a power supply unit for a fork or a drive motor). The memory 25 contains programs necessary for the operation of the computer 20.

It stores various input data, calculation results, etc. The data setting unit 24 is for an operator to set data necessary for control.

FIG. 3 shows the operational flow of the portion of the computer 20 in FIG. 2 related to the embodiment of the present invention. Based on the command Cζ from the host computer 30, the computer 20 determines a speed pattern for driving the stacker crane 1 to the target position corresponding to the command and stopping it, and applies this to the speed adjustment section (not shown) of the travel motor 10. Output. As a result, the stacker crane 1 starts traveling. The operation shown in FIG. 3 is started by the start of travel, and before stopping, the lifting height 11 of the lifting body 7 and the weight iw of the load 13 at the time of stopping are input. This is step Fl in FIG. Here, the lifting height l9
The reason for inputting the weight is the shaking condition (swinging frequency) of the stacker crane 1.

This is because it is a variable parameter that has a large influence on the amplitude of vibration. Note that if / and W are known, this can be handled by inputting that data, and in this case it is not necessary to install a detector. For example, if the weight gkW of the load 13 is known, this information may be given to the computer 20 from the host computer 30 or the data setting section 24.

Once the parameters that affect the shaking at one stop of the stacker crane (especially the variable parameters mentioned above) are input, this parameter is used to determine the waiting time t.
Determine a. This step is F2 in FIG. In this embodiment, the waiting time ta is calculated using a formula derived from the relational expression described below. The equivalent bending stiffness of the stacker crane 1 in the traveling direction is EI (Kgf-7
), the mass of the post 6 is mp (Kg), the mass of the upper frame 18 is mu (Kg"l, the mass of the load 1ζ determined from the weight W of the load 13, the mass of the lifting body 7 (including the fork device) is added. The mass of the lifting unit 17 is mCKg), the height of the post 6 is /max(Q++), and the lifting height of the lifting body 7 when stopped is /
(ffl), the vibration system of the stacker crane 1 is expressed as shown in FIG. Natural frequency ω at this time
(rad/s) is expressed by the following formula.

"'r=±tz"max<mu+8mp>+1!
3-m +=two positive °m (1+αβ3)...
・・・・・・・・・(1) Here, m0=mu+τmp m=α”m□ l=β・I!ma! α; Coefficient related to weight β; Coefficient related to lifting height 1 In equation (1), The natural frequency ω becomes the minimum value ωmin when the lifting height j is l=1max (that is, β=1)
This is a case where the mass m is the maximum value mmaX<the load 3 is equal to the rated weight I). Coefficient α at this time
If αmax (=mmax/mo), then 0m
In is represented by the following formula.

Using 0 mIn expressed by equation (2), the natural frequency ω
ω can be expressed by the following formula.

For example, αmjl! For the case of = 1, the characteristic perturbation number ω
Lifting height relative to Iζ! , the influence of the mass m of the lifting section 17 is determined as shown in FIG.

Further, the inertia force P during braking of the stacker crane 1 is expressed by the following equation, where g1 is the deceleration during braking, and me is the equivalent mass.

P=me@g・old・・・・・・・・・・・・・・＋41Here, me=(1+αβ)m.

During braking, the maximum initial displacement when a constant deceleration g acts for a certain period of time is such that the natural frequency ω is the minimum value ωm11
The displacement X of the top of the post 6 in the running direction after the maximum initial displacement max is the portion surrounded by two curves approximately expressed by the following equation -rωtX=±A-e...・・・・・・・・・・・・・・・(
6) results in a damped oscillation in which the maximum and minimum values periodically fluctuate. This situation is shown in FIG. The time (waiting time) ta required for the displacement X to attenuate below a preset allowable value xa is expressed by the following equation.

/n(xa/person) ta=-□・・・・・・・・・(7) reω If this equation (7) is rewritten as an equation using AmaX and 0 mIn, the waiting time ta is expressed by the following equation. It will be done.

The damping ratio r and the maximum initial displacement Amax are values determined experimentally or by theoretical analysis. αm yo is also a value determined in advance. These values are stored in memory 25 in advance.

Therefore, the calculator 20 can calculate the waiting time ta by performing the calculation of equation (8) using the input parameters.

Returning to FIG. 3 again, once the waiting time ta has been determined, a stop signal timing indicating when the stacker crane 1 is stopped is waited for.

When this timing is input in step F3, step F5. A judgment operation as indicated by F6 is performed. This is a judgment as to whether the output t of the timer that measures the time from the time of stopping matches the waiting time ta, and when the output t of the timer becomes t=t a, the process proceeds to the next step F7. In step F7, a control signal (fork activation signal) for operating the fork device 8 is output at this timing. The control shown in FIG. 3 can be performed every time the stacker crane 1 stops traveling.

In the embodiments described above, the waiting time ta is calculated each time, but the present invention is not limited to this. That is, a waiting time table is created in advance using the lifting height l of the lifting body 7 and the weight W of the load 13 as parameters, and is stored in the memory 25, and the waiting time table is used from the input l and W. The corresponding waiting time ta may be extracted. FIG. 7 shows the operation of the computer 20 in such a case. In FIG. 7, step P11. At F12, l and W are input. In step F13, the corresponding waiting time t is selected from the waiting time table created in advance using this input value.
Extract (search) a.

Steps F14 to F18 are the same operations as steps F3 to F7 in FIG. 3. Therefore, the explanation thereof will be omitted.

According to the first embodiment of the present invention described above, the height of the lifting body and the weight of the lifting body including the load, which are parameters that have a large influence on the shaking condition, are input, and these variables are used to determine the actual shaking condition. The fork device is operated by estimating the amount of time required for the shaking state to fall below the allowable value and using this time as the waiting time, so the waiting time is minimized and cargo handling efficiency is improved.

In the above-mentioned embodiment, each parameter was detected by each detector, but the present invention is not limited to this. It goes without saying that parameters can be set as data, and even if it is not the parameter itself, it can be used to detect changes in the parameter. A correspondingly varying physical quantity may also be used. For example, in the case of weight detection, the weight of the lifting section may be estimated from the current of the drive motor of the lifting device.

〔Effect of the invention〕

As explained above, according to the present invention, the waiting time for fork operation when the stacker crane is stopped can be shortened, and cargo handling efficiency can be improved by that much.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the entire stacker crane in an embodiment of the present invention, Fig. 2 is a diagram showing a control device part in an embodiment of the invention, and Fig. 3 is a diagram showing the control device shown in Fig. 2. FIG. 4, FIG. 5, and FIG. 6 are diagrams for deriving a mathematical formula for determining the waiting time, and FIG. 7 is a diagram showing the operation flow of the control device. 1...Stacker crane, 2...Shelf, 3...Travel seal, 4...Guide rail, 5...Lower frame, 6 ...Post, 7...Elevating body, 8...Fork device, 9a, 9b...Wheel, 10...
Motor, 11...Lobe or wire, 12
...Lifting device, 13...Load, 14...
...Detector, 15...Detector, 16...
...Object to be detected, 17... Lifting section, 18...
...Upper frame, 19...Control panel, 20...
・・・・For control Figure 1 Figure 2 Figure 3; Figure 1-5 Memaχ Besai Otsu diagram Off □ 1 card □ No m-6) Nitto Seigo) Uke]] i1 Niko-r: u - F/4 F15 -F/6 -F Tour F/8

Claims (1)

[Scope of Claims] 1. A method for controlling a stacker crane having a traveling function of traveling along a shelf for storing loads and an elevating function of moving an elevating body in the height direction of the shelf, comprising: Detect parameters that affect the vehicle before the stop, use the detected parameters to estimate the shaking condition after the stop, and determine the waiting time until the shaking condition becomes less than the allowable shaking amount. A method for controlling a stacker crane, characterized in that a fork device provided on the elevating body is operated immediately after the waiting time has elapsed since the stop. 2. In the control method according to claim 1, the parameter is a physical quantity related to the weight or weight of the elevating body including a loaded load, and a physical quantity related to the elevating height or the elevating height of the elevating object. A method for controlling a stacker crane, characterized in that: 3. In the control method according to claim 1, the waiting time is determined using a waiting time table stored in advance according to each value of the parameter, and the waiting time is determined in accordance with the input value of the parameter. A method for controlling a stacker crane, characterized in that a waiting time for a stacker crane is determined from the table. 4. In a stacker crane control device that controls a stacker crane equipped with a traveling device for traveling along a shelf, an elevating body that moves up and down in the height direction of the shelf, and an elevating device that moves the elevating body up and down. , a detection means for detecting a parameter that affects the shaking of the stacker crane, and an output value from the detection means is inputted before the stacker crane is stopped, and the input value is used to control the vibration of the stacker crane. Calculating means for calculating a waiting time until the shaking state after the time of stopping becomes equal to or less than the allowable shaking amount, and outputting an operation signal for operating a fork device provided on the elevating body after the waiting time has elapsed from the time of stopping; A control device for a stacker crane, characterized in that it is provided with.