JPH06255984A - Automatic swinging-control method of crane - Google Patents

Abstract

PURPOSE:To restrain the swinging of a crane in a short time, and to stop it in a specific position by correcting the moving velocity on the basis of the positional deviation from an objective position and the phase and magnitude of the swinging, so that both the restrain of swinging at the time the crane reached the specific position and the positioning can be simultaneously carried out. CONSTITUTION:When a swinging-restrain acceleration correction value is caused, both the deviation between the swinging inherent in the velocity pattern and the swinging detected by a sensor, and the angular velocity of the swinging are input so as to bring the deviation and the angular velocity to zero. By integrating the correction values of this acceleration, a velocity correction value Vss is obtained. By integrating the velocities obtained by a pattern generation mechanism, the position of a crane is obtained. The actual position of the crane is obtained by counting the pulses generated by the encoder that has been fitted to the driven wheel of the crane, by means of a counter. By proportionally integrating these deviations, a velocity correction value Vp is obtained. In the control system, a velocity pattern based on the moving distance being output from an operation command unit is generated, and thereto the velocity correction value Vss for restraining swinging and the velocity correction value Vp for controlling the position are synthesized, and this is made to be the velocity command value of an inverter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic crane control method, and more particularly, to an anti-sway control method for an overhead crane, which is suitable for controlling the oscillation of a suspended load that is required during automation.

[0002]

2. Description of the Related Art During operation of an overhead crane, a load suspended by a wire rope is likely to cause a load swing, and on the other hand, the suspended load needs to descend to a predetermined position without swing. For this reason, program control, fuzzy control, or the like is generally adopted, and as a result, a control means for making the shake zero when stopped is adopted. As an example of this, Japanese Patent Publication No. Sho 61-
No. 31029 and Japanese Patent Publication No. 4-59596.

[0003]

In the conventional method, since the control is performed without measuring the swing condition of the load, optimum control cannot be performed according to the suspended load condition and the shake condition.
Further, even in the method of measuring the shake, the time required for suppressing the shake depends on the cycle of the shake of the load, and the shake cannot be suppressed in a short time.

It is an object of the present invention to provide a control method for a crane, which suppresses a shake generated during traveling of the crane in a short time and stops at a predetermined position.

[0005]

The present invention has been made to achieve the above object, and in a steady rest control method of an overhead crane for suspending and moving a suspended load with a rope, the length of the rope, the suspended load of the suspended load, and the like. When the crane moves a predetermined distance, the speed and the load are detected as the speed pattern that makes the shake caused by the acceleration / deceleration of the crane zero when stopped.The shake during constant speed movement, deceleration or stop of the crane , The length of the rope, the deviation of the position from the target position, the phase and magnitude of the shake, and the movement speed is corrected to simultaneously suppress the shake when the vehicle arrives at a predetermined position and perform alignment.

[0006]

The present invention moves a predetermined distance by a speed pattern that becomes zero when the shake caused by the acceleration and deceleration of the crane by itself is stopped at a predetermined position, and the shake generated during running is being moved at a constant speed or during deceleration. Or, in a stable area where the shake during a stop maintains a constant angle, compare the shake caused by accelerating and decelerating the crane with the shake of the actual load, and correct the moving speed so that the difference between the two becomes zero. , Suppress the shake. The predetermined position is moved to a predetermined position by comparing the actual position with a position obtained by integrating the speed of the crane and correcting the moving speed so that the deviation between the two and the accumulated deviation become zero. The runout caused by the acceleration / deceleration of the crane is described as a simple pendulum with the upper end fixed. The swing of a simple pendulum does not originally depend on the weight of the suspended load, but is determined by the length of the rope and the acceleration of gravity, but cranes have suspenders to hold the load in a stable state. The center of gravity moves due to the weight of the load and the weight of the suspended load, and the swing cycle of the load is different from the cycle determined by the rope length. The weight is measured to correct this cycle. The suppression of runout is the runout (θp) caused by the acceleration / deceleration for the movement of the crane and the actual runout (θ
The acceleration is controlled so that θerr is always zero on the phase plane represented by the difference (a) (θerr = θp−θa) and the angular velocity of the shake.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A steady rest control method for an automatic crane according to the present invention will be described below with reference to the illustrated embodiments. The movement of the crane is performed independently of traverse and traveling, but the traveling movement will be described next.

(1) Mechanism of speed pattern generation The speed pattern has four areas: an acceleration area, a constant speed area, a deceleration area, and an adjustment area. In the acceleration region in the velocity diagram of FIG. 1, the region of FIG. 1 alternates the acceleration between the rated acceleration a of the crane and zero at a cycle of 1/6. The time in the region of FIG. 1 is the time obtained by subtracting 1/3 of the cycle from the time required to accelerate to the maximum speed.

As a result, in FIG.

[0010]

[Formula 1]

[0011] When the position is maintained while maintaining the above, both the deflection angle θ and the angular velocity ω become zero.

The deceleration area is decelerated from the maximum speed to the speed of the low speed adjustment area. The area of FIG. 1 and the position of the circle 11 are acceleration -a, and the time is 1/6 of the cycle. And the circled circle 10 sets the acceleration to -a / 4 and the time

[0013]

[Formula 2]

[0014]

[Formula 3]

The reason why the acceleration of the area and the circled circle 10 is not zero is to reduce the control error in the transient response of the control system and improve the followability.

The adjustment area circled 12 decelerates in one cycle at an acceleration smaller than the rated acceleration, for example, 1a / 8. As a result, the shake and angular velocity when stopped are zero.

In the constant velocity area, the moving distances of the acceleration area, the deceleration area, and the adjustment area are subtracted from the moving distance to the target, and the remaining distance is moved at the rated speed. When the moving distance is small and acceleration to the maximum speed is not possible, the maximum speed is suppressed according to the moving distance. This makes it possible to generate a basic speed pattern that moves to an arbitrary target point.

(2) Shake suppression mechanism The stable point of shake is a point where both the shake angle and the angular velocity are zero.
Instead of directly bringing the shake angle to zero, control is performed so as to bring the deviation of the shake unique to the speed pattern generated by the speed pattern generation mechanism and the shake measured by the sensor to zero. The peculiar shake of the pattern is obtained by differentiating the speed pattern to obtain acceleration, and by solving the equation of motion of the simple pendulum model with this acceleration, the shake (θp) can be obtained for any speed pattern.

The shake suppression acceleration correction value is generated by inputting the shake unique to the speed pattern, the deviation of the shake detected by the sensor, and the angular velocity of the shake, and the deviation θerr = by the bang-bang control.
θp-θa and its angular velocity

[0020]

[Formula 4]

The acceleration correction value is switched as shown in FIG. If the state is a, control ass = -k,
When it arrives at c, it switches to ass = k. If it is b, it arrives at d with ass = k and switches to ass = -k. This switching line-changes depending on the length of the pendulum and the responsiveness of the crane.

The acceleration correction value is integrated to obtain the speed correction value Vss. The shake suppression operation can be performed in all areas of circled circle 12, and the amount of operation to be added is variable for each area.

(3) Position control mechanism The shake suppressing mechanism changes the moving speed of the crane to suppress the shake, and the crane arrives at a position deviated from the target position. Therefore, the position controlling mechanism corrects this. Guide to the target position.

The speed (xp) of the crane is obtained by integrating the speed obtained from the pattern generating mechanism. The actual position of the crane is obtained by counting (xa) the pulses generated by the encoder mounted by the driven wheels of the crane with a counting counter. A velocity correction value vp is obtained by proportionally integrating the deviation of xp-xa.

If the positional deviation due to the shake suppression is to be corrected, a method of integrating the speed correction value vss for suppressing the shake and controlling so that this value becomes zero is also devised. In addition to the above, the method includes a method of correcting only the positional deviation of the runout described above, since the positional error in the entire drive system of the crane can be suppressed.

(4) Overall control In the control system, a speed pattern is generated based on the moving distance output from the operation command, and a speed correction value for suppressing shake at this speed,
The speed correction value for position control is combined and used as the speed command value for the inverter.

In the control of this system, a vector control inverter having a wider speed control range and excellent responsiveness than an open loop type inverter of V / F control is suitable. The drive device is not limited to the combination of the inverter and the induction motor as long as the drive response of the motor is about 10 rad / s or more, and any type such as a servo motor or a DC motor can be used.

[0028]

EFFECT OF THE INVENTION The steady rest control method for an automatic crane according to the present invention is a steady rest control method for an overhead crane which suspends and moves a suspended load with a rope, and detects the length of the rope, the load of the suspended load, and the swing of the load. When the crane moves a predetermined distance, the speed pattern that makes the vibration caused by the acceleration / deceleration of the crane zero when stopped is used as the speed pattern of the crane during constant speed movement, deceleration or stop, and the rope length and the target position. Deviation, and the phase and magnitude of the shake, the moving speed is corrected, and the shake is suppressed and aligned at the same time when arriving at a predetermined position.Therefore, it is possible to reliably control the shake of the suspended load. is there.

[Brief description of drawings]

FIG. 1 is a velocity diagram of a crane showing a steady rest control method for an automatic crane of the present invention.

FIG. 2 is an in-phase diagram.

FIG. 3 is a block diagram for explaining the same shake suppression.

FIG. 4 is a switching diagram.

FIG. 5 is a block diagram of a position correction mechanism.

FIG. 6 is an overall block diagram showing an embodiment of a steady rest control method for an automatic crane according to the present invention.

[Explanation of symbols]

 ass Acceleration correction value g Gravity acceleration K Proportional constant l Suspended rope length S Laplace conversion operator T Integral constant V Crane movement speed Vss Speed correction value Vp Position control speed correction value xp Crane position xa Actual position θp Caused by pattern Runout θa Actual runout θerr Runout deviation

Claims (1)

[Claims] 1. In a steady rest control method for an overhead crane that suspends and moves a suspended load with a rope, the length of the rope, the load of the suspended load, and the swing of the load are detected, and when the crane moves a predetermined distance, the crane The speed pattern is set so that the shake caused by acceleration / deceleration of the crane becomes zero at the time of stop, and the shake during constant-speed movement, deceleration or stop of the crane is calculated from the rope length, the deviation from the target position, the shake phase and magnitude. A method for controlling a steady rest of an automatic crane, characterized in that the moving speed is corrected, and the runout is restrained and the position is adjusted at the same time when the vehicle reaches a predetermined position.