JP3243346B2 - Control termination method for crane steady rest control - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the control of an overhead crane which suppresses the deflection of a running load by suppressing acceleration and controls position control by controlling the speed by the difference between a target position and an actual position. In particular, control for vibration suppression and adjustment to the target position
After the position control is completed,
The present invention relates to a control end method of a steady rest control of a crane that can accurately stop at a mark position .

[0002]

2. Description of the Related Art A conventional anti-sway control method judges the convergence of a run-out and the matching of a position, stops the output of an inverter when a condition is satisfied, brakes the crane by a braking means such as a brake, and stops the crane. .

[0003]

In this method, the control is stopped in the shortest time when the control is stopped, so that the position can be stopped without shifting. However, the load is shaken by the negative acceleration due to the application of the brake. For this reason, there was a drawback that accurate shake suppression control could not be performed. Further, when control is continued until the control output of the vibration suppression and the position control becomes zero, there is a disadvantage that it takes time for the control to converge.

[0004] The present invention is, after the end of the position control to match the suppression control and goal position of deflection, provides a way to stop accurately at the target position without be large oscillations of suspended load, to improve the control performance of the crane The purpose is to:

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and a vibration control mechanism for controlling a vibration during traveling of a crane by controlling a traveling acceleration, and an object for monitoring a suspended load. In an overhead traveling crane having a position control mechanism for guiding to a target position, the allowable range of the target position and the allowable range of the amplitude
Is set to the middle position where the suspended load does not reach the tolerance of the target position.
At the position, run-out suppression control and position control are performed,
Within the allowable range of the mark position, and the vibration is within the allowable range of the amplitude.
When entering, stop the vibration suppression control and
Stop the control and then control the remaining runout and position
Stop the load at the target position by gradually reducing
It is characterized by making it.

[0006]

In order to suppress the vibration and control the position by controlling the vibration in a coherent manner, if the acceleration is controlled, the control amount of the acceleration becomes a disturbance of the position control, and the position changes. If the moving speed is controlled to control the position, the acceleration of the control amount becomes a disturbance of the shake suppression control, and a positive or negative shake occurs. Therefore, for the control of the shake and the control of the position, the target value (permissible value) of each control has a range, and the determination of the shake target is performed when the shake is within the target range and the position is also within the target range. To stop the vibration suppression control. After that, only the position control is continued. After the run-out suppression is over,
If the position of the suspended load is within the target range, the position control is also stopped. After the end of the shake control, if a shake occurs during the position control, the shake suppression control is restarted. When the position control is stopped, the shake control amount and the position control amount are not zero. Therefore, the control amounts are converged to zero at a constant acceleration. As a result, the crane is stopped and the control is terminated while maintaining the state in which the amount of shake and the error in the position can be predicted.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a control termination method for a steady rest control of a crane according to the present invention. As shown in FIG. 1, the steady rest control device 1 controls a traveling speed of a crane and generates a speed command so as to reach a target position, and a shake suppression control mechanism that controls acceleration and suppresses shake. 3, a position control mechanism 4 for controlling the traveling position and stopping the control when the stop position is reached, and a stop position correcting mechanism 5 for correcting the stop position after the end of the position control.

When the moving distance of the crane is given, the speed commanding mechanism 2 generates a speed command according to the moving distance and gives it to the inverter IV to drive the induction motor IM.

The load vibration suppression control machine includes a vibration control mechanism 10 for switching a control amount according to a load fluctuation state and a vibration control release mechanism 11. Depending on the state of the load deflection, the deflection control mechanism 10 determines that the deflection is 2 in the phase plane with the deflection angle θ and the deflection angular velocity θ ′ / ω of the load as the coordinate axes.
Among the divided areas, SW1 is switched to 1 in an area above the switching line, and SW1 is switched to 2 in an area below the switching line.
The control amount is supplied to the inverter IV through the primary delay circuit 12 and the operation circuit 6 via the primary delay circuit 12 to provide a speed control amount signal for suppressing vibration.

The swing control release mechanism 11 switches the switch SW2 to 2 when the suspended load arrives in the allowable range near the target position and the amplitude of the shake falls within the allowable range, and the shake constant = 0, that is, the swing Stop the suppression control.

The position control mechanism 4 includes a position control mechanism 13 for controlling the position based on the difference between the target position and the current position at time t from the start, and a position control release mechanism 14 for switching the speed control amount to zero when the position control is stopped. And The position regulating mechanism 13 adjusts the current position of the crane t hours after the start to the calculated position after the lapse of the time, that is, the target position. Are compared, and the difference is proportionally integrated to obtain a speed correction amount.

When the anti-sway control is already stopped near the target position, the position control release mechanism 14 switches the switch SW.
3 is switched to 2, the control value is set to zero, and the position control is stopped.

The stop position correcting mechanism 5 includes a rate-of-change limiting mechanism 15 for limiting the maximum rate of change per unit time of the speed command input to the inverter to a constant value after the end of position control, and a load swing and target And a switch SW4 for judging the stop of the above-mentioned control based on an error in the position of the switch SW. When the position control is stopped, the control amount of the shake suppression control and the position control amount are generally not zero. For this reason, the rate-of-change limiting mechanism 15 gradually converges the control amount to zero, and sets the switch SW4 so as not to generate a large swing during this time.
Is switched to 2, and the control amount is gradually released by the rate limiter that limits the rate of change per unit time. The distance traveled during the release of the control amount is determined by the speed at the time when the switch SW4 is switched and the rate of change (acceleration) of the rate limiter.

FIG. 2 shows a control flow chart of the present invention having the above configuration. First, the distance from the start position of the crane to the stop position of the suspended load is measured by the speed command mechanism 2, the transport speed is set, a command output is applied to the inverter IV, and the motor IM is driven. With the traveling of the crane, the traveling distance from the traveling time, and hence the remaining traveling distance, is measured. At an intermediate position where the remaining distance is larger than the allowable distance 1 (which will be described later), that is, the intermediate position where the remaining distance does not reach the allowable distance, The shake suppression control mechanism 3 and the position control mechanism 4 simultaneously control shake suppression and position control. When the remaining distance is smaller than the remaining distance allowable value 1, that is, within the allowable value, and the swing of the suspended load is within the allowable value, the switch SW2 of the load swing suppression control mechanism 3 is switched to 2, and the swing Release control.

Next, the remaining distance is the allowable distance value 2 (described later).
If the shake suppression control is already stopped within a smaller range, that is, within the allowable range of the stop position, the switch 3 is switched to 2 and the switch SW4 of the stop position correction mechanism 5 is switched to 2 side. This is to gradually reduce the amount of control of the remaining shake and position by the change rate limiting mechanism 15 as described later, and to stop at a predetermined position. When it is confirmed that the speed is 0, that is, in a stopped state, the control is terminated. Incidentally, the remaining distance is than the distance tolerance 2 large, i.e. can the Most Do not reach the stop position tolerance repeats the control from the beginning.

The above-mentioned distance allowable values 1 and 2 are set in advance, and the control condition can be selected according to the magnitude relation between the judgment conditions. (A) When the remaining distance allowable value 1> the remaining distance allowable value 2, the shake is preferentially suppressed, and the position is adjusted thereafter. (B) When the remaining distance allowable value 1 <the remaining distance allowable value 2, the position is preferentially adjusted.

When the position control is stopped, the control amount of the shake suppression control and the position control amount are not generally zero as described above. For this reason, the switch SW4 is switched to 2, and the control amount is gradually released by the rate limiter that limits the rate of change per unit time. Assuming that the time from when the switch SW4 is switched to when it is stopped is t, t = (Vs + Vp) / a (1)

Assuming that the moving distance from when the switch SW4 is switched to when it is stopped is L, L = (Vs + Vp) t / 2 (2)

[0019]

(Equation 1)

In the equation (3), the first term indicates the shake caused by the acceleration of the rate limiter, and the second term indicates the continuation of the shake when the switch SW4 is switched. The first term is π / 4
And the value is a / g.

The travel distance, travel time, and runout after the control is stopped can be estimated. By taking into account the behavior after the stop with respect to the final required accuracy, the allowable value of the remaining distance and the allowance of the runout are set. Control that satisfies errors in the magnitude and position of the shake can be performed.

FIG. 3 shows the state of the control output. That is, position A
Until the position A, both the shake suppression and the position control are performed.
Stops vibration suppression at. At the position B, the position control is also stopped. Each control amount as described above at this time is not Tsu name to zero. For this reason, the stop position correction mechanism 5 is operated, and the control amount is gradually converged to zero by the change rate per unit time set in the change rate limiting mechanism 15,
Stop at the stop position C. FIG. 4 is a phase diagram showing the effect of the steady rest. In FIG. 4, reference numerals are as follows. θ Load swing angle ω Angular velocity T Switching line for switching the movement acceleration for steadying The load swing draws a circular trajectory on the phase plane without control. When the deflection of the load reaches the point A on the phase plane, the switch SW1 is switched to the side of 1 to apply a positive acceleration to the load and cause the phase plane trajectory to move inward. Further, when the point B is reached, the switch SW1 is switched to 2, and a negative acceleration is applied to move the phase plane trajectory further toward the inner center. In the present embodiment, an example is described in which the trajectory reaches point A first.
When arriving at the point earlier, a negative acceleration can be applied first.

[0023]

As described above, the control termination method of the anti- sway control of the crane according to the present invention controls the run-out during crane running by controlling the acceleration of the running, and guides the suspended load to the target position. In an overhead traveling crane equipped with a position control mechanism, the allowable range of the target position and the allowable range of the amplitude
Set to an intermediate position where the load does not reach the target position tolerance
Control the run-out and position control, and
The position is within the allowable range, and the vibration is within the allowable amplitude range.
Stop the vibration suppression control and
Control and then control the remaining runout and position
The load is stopped at the target position by gradually reducing the load.
Since the cause, can be stopped accurately at the target position without be large oscillations of the load suspended on the control of after the end, cranes
Control performance can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of control in a control termination method of a steady rest control of a crane according to the present invention.

FIG. 2 is a control flowchart.

FIG. 3 is an explanatory diagram showing a state of a control output.

FIG. 4 is a phase diagram showing the effect of the steady rest.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anti-sway controller 2 Speed command mechanism 3 Anti-sway control mechanism 4 Position control mechanism 5 Stop position correction mechanism Vs Anti-sway control output Vp Position control control output a Maximum rate of change of rate limiter t Moving time after stop of position control L Position Movement distance after control stop g Gravitational acceleration θ (0) Shake angle at stop of position control θ '(0) Shake angular velocity at stop of position control θ (t) Shake angle at stop ω Angular velocity

Claims (1)

(57) [Claims] And 1. A crane runout traveling control the acceleration of the traveling suppressing vibration control mechanism, the overhead traveling crane having a position control mechanism that induces the suspended load in the target position, and the allowable range of the target position Set the amplitude tolerance and
In the middle position where the suspended load does not reach the tolerance of the target position,
Performs run-out suppression control and position control so that the suspended load
If the vibration falls within the allowable range and
In this case, stop the vibration suppression control and stop the position control.
Stop, and then gradually reduce the remaining vibration and position control amounts.
A method for terminating the steadying control of a crane, characterized in that the load is stopped at a target position by reducing the load .