JPH0422802B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a control method for a stacker crane, and particularly to a control method for reducing shaking when a stacker crane stops running. [Background of the Invention] Stacker cranes are often used as cargo handling machines in automated warehouses. A normal stacker crane transports the load to a target shelf by loading the load onto an elevating body, traveling along the upper and lower rails using a traveling device, and raising and lowering the elevating body using a lifting device. It is. The running device of a Statzker crane consists of wheels that run on rails, a drive motor that provides rotational driving force to the wheels, and a power adjustment unit (for example, a thyristor power converter) that adjusts the power supplied to the motor. configured. In order to support the stacker crane, a rail is also provided on the upper part, and guide rollers are attached so that it can run along the rail. Now, as a shaking prevention mechanism to prevent the shaking of the Stutzker crane that occurs when the Stutzker crane travels to the target position, there is a mechanism that uses electromagnets and friction members to stop the shaking by braking. It is publicly known. This is disclosed, for example, in Japanese Utility Model Publication No. 49-10624. Such a known anti-sway mechanism for a stacker crane is useful for preventing shaking when the crane is stopped, thereby increasing the efficiency of the stacker crane. Incidentally, recently, there has been a trend toward the construction of higher-rise warehouse shelves with the aim of increasing the storage density of automated warehouses. Along with this, the height of the stacker cranes used for loading and unloading cargo onto warehouse shelves has become higher, and they have also started to run at higher speeds in order to improve cargo handling efficiency. Under such circumstances, the conventional shaking prevention mechanism alone is insufficient to prevent the stacker crane from shaking when the crane is stopped, resulting in the problem that it takes time for the shaking to become smaller. In order to reliably prevent shaking of a large-sized, high-speed stacker crane, a large-scale shaking prevention mechanism is required to prevent it, which increases the weight of the stacker crane and significantly increases its price. . [Object of the Invention] An object of the present invention is to provide a control method for a stacker crane that can reduce shaking of the stacker crane with a simple configuration. [Summary of the Invention] The present invention determines the traveling distance and traveling speed of the upper traveling device of a stacker crane, and also determines the traveling distance and traveling speed of the lower traveling device, and calculates the deviation of the vertical traveling amount and the vertical traveling distance. Determining the speed deviation, determining a speed control signal for at least one of the upper and lower traveling devices from the traveling distance deviation and the traveling speed deviation, and outputting the determined value to the target traveling device. It is characterized by the following. [Embodiments of the Invention] The present invention will be described in detail below with reference to the drawings. FIG. 1 is a control block diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing the running status of the Statzker crane, FIG. 3 is a diagram showing the configuration of the Statzker crane, and FIG. 4 is an enlarged view of a part of FIG. 3. FIG. 5 is a diagram showing the speed pattern of the stacker crane, and FIG. 6 is a diagram showing the control operation flow of the embodiment shown in FIG. 1. First, the overall structure of the stacker crane 1 used in the embodiment shown in FIG. 1 will be explained with reference to FIGS. 3 and 4. In FIGS. 3 and 4, 200 is a warehouse shelf, 300 is an upper rail, and 400 is a lower rail. The stacker crane 1 is arranged between upper and lower rails 300 and 400 and moves along these rails. 10
1 and 102 are wheels running on the lower rail 400, and 103 and 104 are wheels running on the upper rail 300. Reference numeral 105 denotes a traveling device provided at the bottom, which drives the wheels 101 to rotate. 1
06 is a traveling device provided at the top, and wheels 1
03 is rotated. 107 and 108 are guide members for preventing the stacker crane from falling; 109 is a lower truck member; 110 is an upper truck member; and 111 and 112 are columns connected between the truck members. Reference numeral 114 denotes an elevating body that lifts and lowers the load 113, and 115 represents a fork device provided on the elevating body. 116 is a rope for lifting and lowering; 117 is a lifting device that lifts and lowers the lifting body 114 by unwinding the rope 116; 118 and 119 are running detection devices for detecting the running speeds of the lower and upper parts, respectively; 120 is an elevation detection device for detecting the elevation position of the elevation body 114. In FIG. 4, 121 is a support plate, 122 is a support member, 1
Reference numeral 23 denotes a mounting member connected to the support plate 121 with a pin. The traveling device 106 is attached to this attachment member 123. 124 is a drive motor, 125 is a gear on the motor side, and 126 is a gear on the wheel 103 side. Next, the embodiment shown in FIG. 1 will be described. In FIG. 1, 1 is the stacker crane shown in FIGS. 3 and 4. In FIG. Reference numeral 2 is a calculation device, and specifically, a microcomputer may be used. 30 and 40 are V/F circuits that convert voltage signals into corresponding frequency signals, 31 and 41 are adders, 32 and 42 are proportional control circuits, 33 and 34
is a limiter, and 34 and 44 are adders. 5 is an inverter circuit, which supplies power at a frequency corresponding to the input signal to each traveling device 105, 106.
is supplied to perform speed control. 6 and 7 indicate integrators. Arithmetic device 2 outputs speed setting voltages V ₁ and V ₂ as command signals. V/F circuit 30, 40
outputs frequency signals f ₁ and f ₂ based on the signals. The inverter circuit 5 inputting this signal via the adders 34 and 44 generates electric power according to the frequency, and transmits this to the upper and lower traveling devices 10
5, 106, the stacker crane 1 is made to travel. The output of the V/F circuit is also output to adders 31 and 41, respectively, and the deviation from the output (speed) of traveling detection devices 119 and 118 is determined.
43, the correction amount of the frequency signal is sent to the adder 34,
44 respectively. In this way, speed control is implemented. Note that the arithmetic unit 2 receives the upper and lower travel distances, which are the outputs of the integrators 6 and 7, and uses these travel amounts to control the stacker crane 1 to prevent it from swinging. This will be explained in detail below. The stacker crane 1 shakes as shown in FIG. 2 while traveling or when stopped.
x ₁ and x _{2 in Fig. 2} indicate the travel distance without shaking. x ₂ ′ indicates the travel distance of the upper part when there is shaking as shown by the dotted line in the figure. Therefore, the instantaneous swing width δ of the stacker crane 1 is expressed by the following equation. δ=x ₁ −x ₂ ...(1) However, x ₁ : Travel distance on the lower side x ₂ : Travel amount on the upper side In addition, the swaying speed δ is expressed by the following formula. δ〓＝dx ₁ /dt−dx ₂ /dt＝x〓 ₁ −x〓 ₂ ...(2) However, x〓 ₁ : Lower traveling speed δ〓 ₂ : Upper traveling speed Movement of Statzker crane 1 Once the desired position is set, the arithmetic unit 2 determines the distance _xr from the current position to the desired position (target travel distance), thereby determining the traveling speed pattern of the traveling device 105. This pattern is, for example, as shown in FIG. The constant speed running period _t4 of the Statzker crane in this pattern is obtained by the following equation. t ₄ = [x _r − {1/2x〓 ₁₀ (t ₁ + t ₇ ) + x〓 ₁₀ (t ₂ + t ₆
) +1/2x〓 ₁₁ (t ₃ + t ₅ )} / x〓 ₁₁ ...(3) However, x〓 ₁₀ : Intermediate speed t ₁ : Time from start of movement to reaching intermediate speed t ₇ : From intermediate speed _Time until stopping t _{2 ,} t ₆ : Time during _which the intermediate speed is maintained Time required for deceleration to speed Now, the traveling speed pattern of the upper traveling device 106 of the stacker crane 1 is also almost the same as that shown in FIG. 5, but in the embodiment of the present invention, the vertical swing width δ is To reduce the speed, control the speed as follows. x〓=x〓 ₂ +k(x-x ₂ ) ...(4) However, x〓: Target speed setting value at current sampling x〓 ₂ : Target speed setting value at previous sampling k: Position speed gain x ₁ : Lower travel amount x ₂ : Upper travel amount In other words, the calculation device 2 uses the vertical travel deviation amount (x ₁ - x ₂ ) to calculate a speed control signal that eliminates this deviation, and converts this into V /F circuit 30. As a result, the amount of vertical travel deviation is reduced, and the shaking of the stacker crane is reduced. Next, the operation shown in FIG. 1 described above will be explained using the flowchart shown in FIG. The flow (steps ~) on the left side of FIG. 6 shows the entire operation from the start of running to the time of stopping. The flow (steps ~) on the right side of FIG. 6 shows the speed control operation to prevent shaking. When the position to which the stacker crane is to be moved is set while the stacker crane is in a stopped state, steps .about. are sequentially executed. Step: Initial settings of the arithmetic unit 2 are performed. Step... Determination of target mileage x _r and
Set the speed pattern using x _r . Further, constant speed running time t ₄ is calculated using equation (3). Step... Clear the current mileage x ₁ and x ₂ to zero. Step: Start traveling and drive the lower traveling device 105 according to the speed pattern described above. The upper traveling device 106 is also driven in the same manner. Then, the deviation (x _1
-x2 ), speed control is performed to prevent shaking to eliminate it. The operation of this step is shown in steps ~ and will be discussed later. Step...The steps are repeated until the vehicle travels close to the destination. That is, |
The steps are repeated until x _r −x ₁ | becomes less than ε ₁ , and when it becomes less than ε ₁ , proceed to the next step. Step......When the lower position of the stacker crane reaches the target stopping position,
While applying the brake, the traveling device 106 is controlled so that the upper position is at that position, and the brake is applied while performing anti-sway control. Next, details of the operation of the above-mentioned steps will be explained using steps . Step: The speed of the lower traveling device 105 is controlled in accordance with the speed pattern at regular intervals. Step: Detecting the distance of elevation as the elevating body 114 moves. Step: Detect travel distances x ₁ and x ₂ . Step...Using x ₁ and x ₂ detected in step, the running deviation amount δ (= x ₁ - x ₂ ) is determined. Step... From the running speeds x〓 ₁ and x〓 ₂ obtained by the speed detectors 118 and 119, the runout speed δ〓 (=x〓 ₁ −
Find x〓 ₂ ). Step......The current driving condition is replaced by the five-stage mode shown in the table below, depending on the deviation amount δ of the traveling distance obtained in the step and the deviation amount δ of the traveling speed obtained in the step, and the upper The gain k used to control the traveling device is determined.

[Table] −← 0 →＋
(x ₁ −x ₂ )

【table】

Claims (1)

[Claims] 1. The travel distance and travel speed of the upper traveling device of the stacker crane are determined, and the travel distance and travel speed of the lower travel device are determined, and the deviation of the upper and lower travel amounts and the upper and lower travel speeds are calculated. determining a deviation, determining a speed control signal for at least one of the upper and lower traveling devices from the deviation of the traveling amount and the deviation of the traveling speed, and outputting the determined value to the target traveling device. Characteristics of the control method of the Stadka crane. 2. Travel distance and travel of the elevating body along the pillar, the lower traveling device installed at the bottom of the pillar, the upper traveling device installed at the top of the pillar and driving the pillar with respect to the upper rail, and the lower traveling device a first means for detecting the speed; a second means for detecting the traveling distance and traveling speed of the upper traveling device; A stacker crane comprising: third means for obtaining a speed control signal for at least one of the traveling devices and outputting it to the corresponding traveling device.