JP2955493B2 - Control method of swing posture of suspended load of crane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for automatically or manually operated cranes for turning a suspended load, and more particularly to a control method for operating the crane to prevent a twisting motion when the suspended load is rotated.

[0002]

2. Description of the Related Art In a conventional automatic crane, it was difficult to stop the twisting motion generated when turning a suspended load, so that the hook sheave portion was raised to the upper limit of hoisting so that twisting did not occur, and mechanically restrained. I was turning while doing it. During manual operation, the turning motor was operated to prevent twisting due to the skill of the driver.

[0003]

When an existing manually-operated crane is converted to automatic operation, the existing equipment is used for the automatic operation due to the dimensional restrictions of the crane and the restriction of the lifting load. It is desired to do. In order to achieve stable conveyance, the swing of the suspended load is controlled by the anti-sway control, which enables the suspended load to be restrained from moving during handling and can be transported to the target position. May fail. In addition, in the transport in which the direction of the load is changed by the swiveling motion, if the appropriate control is not performed, the handling must be interrupted until the torsional motion is attenuated, and a practical transport capability cannot be realized.

[0004] It is an object of the present invention to attenuate this harmful torsional movement in a short time and to realize a transport while maintaining a stable posture of the suspended load.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and comprises a swing mechanism driven by a motor between a hook sheave portion and a grip portion for fixing a suspended load on a hanging portion of a crane. , A inverter for driving a turning motor, and a mechanism for generating a turning speed command to be given to the inverter in response to a turning angle command. The gist is that a speed pattern is created, the motor is driven by an inverter, and the occurrence of a twist angle is minimized.

[0006]

[Operation] The swivel device is driven by an electric motor rotating at an arbitrary speed by an inverter, and rotates the lifting gear and the suspended load via a speed reducer. In response to the command of the turning angle, the torsional motion solves the equation of motion of a simple vibration with a natural frequency determined by the moment of inertia of the load and the lifting gear and the spacing and length of the wire rope that suspends the load, and a combination of a single acceleration Create a pattern of turning speed that does not generate twisting at constant speed operation and twisting at the end of turning with
The inverter-controlled motor is driven in accordance with this speed pattern to minimize the occurrence of a twist angle.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a method for controlling a swinging posture of a suspended load of a crane according to the present invention. In the crane A shown in the figure, 1 is a girder of the crane, and 2 is a club traveling on a crane gutter. And this gata 2
The hanging tool 9 is hung vertically by the wire rope 4 from the hoisting drum 3 and the head sheave 11 provided in the above. The hanging tool 9 is divided between the hook sheave portion 10 and the turning mechanism 8, and the hanging tool 9 is rotated by the turning mechanism 8 including the turning motor 6 and the gear 7.

FIG. 2 shows the configuration of the control device. The turning angular velocity command gives a patterned speed command corresponding to the turning angle. The speed command pattern is determined by the natural oscillation period and the turning angle determined by the length and interval of the wire rope supporting the suspended load, the weight of the suspended load, and the moment of inertia of the turning portion.

The turning speed of the turning mechanism is significantly lower than the rotating speed of the electric motor, and the reduction ratio is preferably 1/100 or less. In addition, when the turning angle accuracy is at most several degrees or less, sufficient speed accuracy can be obtained even when driven by a combination of a general-purpose inverter and an induction motor. The mechanism for detecting the rotation angle can be omitted.

The natural vibration period ω of the torsion is determined by the moment of inertia J1 of the portion above the turning mechanism of the lifting device, the moment of inertia J2 of the portion below, the lifting load W, the length 1 of the wire rope, and the distance between the wire ropes. When r is obtained, the following equation is obtained.

[0011]

(Equation 1)

From the natural vibration period ω, the initial condition at the start of turning is defined as a velocity pattern, and the solution at which the torsion angle is set to zero and the end of the turn is set to zero is defined as a speed pattern. Thus, the vehicle turns without causing torsional vibration at the target angle.

FIGS. 3, 4 and 5 show examples of the speed pattern.
Shown in This speed pattern is constituted by a combination of a single acceleration, and is suitable for driving the turning with a general-purpose induction motor and an inverter.

FIG. 3 (a) shows that acceleration is performed in one cycle of the natural period of torsion.
It is the simplest speed pattern figure which performs deceleration. Since the constant speed portion does not twist, the turning time of the constant speed portion can be determined only by the turning angle and the turning speed regardless of the twisting cycle. The maximum speed N during turning is N = aT. Here, a indicates the angular acceleration of the turn.

FIG. 3b shows a trajectory diagram of the torsional phase plane for this velocity pattern, ie, starting point 0 (zero torsion angle).
During acceleration, the maximum torsion angle reaches (−θa) by drawing a circular locus on the left side, and then decreases and returns to the origin O at a constant velocity portion. At the time of deceleration, the maximum torsion angle draws a right circular locus. After reaching (+ θb), it decreases thereafter and returns to the starting point 0 (zero torsion angle) when stopped.

FIG. 4A is a speed pattern diagram for performing acceleration / deceleration in a combination of a quarter of the natural period. Also in this embodiment, since the constant speed portion does not twist, the turning time of the constant speed portion can be determined only by the turning angle and the turning speed regardless of the twisting cycle. The maximum speed N during the turn is N = aT / 2.

FIG. 4B shows a phase plane locus diagram during acceleration, which is a combination of π / 4, π / 2, and π / 4 arcs on the left half surface. That is, it twists from the origin O in the direction of the arrow, reaches the maximum twist angle (-θc) after T / 4 hours, shifts to the constant speed operation, then shifts to the acceleration operation again, and stops at the origin O when reaching the rated speed. During deceleration, the trajectory is symmetrical on the right half surface. In this case, as is apparent from FIG.
The twist angles (−θc) and (+ θd) are all (−θa) of the previous example.
(+ Θb).

FIG. 5A shows a speed pattern in which acceleration and deceleration are performed in a combination of 1/6 period of the natural period. Also in this embodiment, since the constant speed portion does not twist, the turning time of the constant speed portion can be determined only by the turning angle and the turning speed regardless of the cycle of the twist. The acceleration time is determined by a combination of a part that depends on the 1/6 cycle and a part that accelerates regardless of the cycle. The maximum speed N during the turn is Nmax>N> aT / 3, and the vehicle can be accelerated to an arbitrary speed. Here, Nmax is the rated angular velocity of the electric motor.

FIG. 5B shows a phase plane locus. After passing through a locus of a combination of circular arcs of π / 6 and π / 6 on the left half surface, FIG.
It stops at the maximum value (-θe) on the horizontal axis. Furthermore, π / 6,
After passing through the trajectory of the combination of circular arcs of π / 6, the vehicle stops at the origin O when the rated speed is reached. At the time of deceleration, a trajectory is drawn on the right half surface, which is symmetrical to that of acceleration. In this case, the maximum twist angle -θe, +
As is clear from FIG. 5B, θf is smaller than the twist angles −θa, −θc, + θb, and + θd in the above-described examples.

These embodiments are selected according to the operating speed and the turning angle. Further, the angular velocity of the turning is N = 1.5a by the combination of the speed pattern of FIG. 3 and the speed pattern of FIG.
It is easy to set to T and to be able to operate at a higher angular velocity by repeating the acceleration pattern a plurality of times.

Although the moment of inertia of a suspended load cannot be directly measured, in applications where the shape of the conveyed object is limited, for example, in applications such as coil transport of steel, the characteristic is easily determined from the correlation between the load of the suspended load and the moment of inertia. Period can be calculated.

In this embodiment, a single combination of accelerations is used. However, even in a combination of a plurality of accelerations, there are various patterns in the solution of the differential equation for making the torsion zero at the end of the turn.

The present embodiment is not limited to the torsional vibration of the load of the crane, but is effective in suppressing the motion (vibration reduction) that can be approximated by a single vibration. For example, the control of the load deflection and the extension of the load wire rope It can also be applied to vibration suppression of vertical vibration.

[0024]

According to the method for controlling the swing posture of a suspended load of a crane according to the present invention, a swing mechanism driven by a motor between a hook sheave portion and a grip portion for fixing the suspended load is provided on the hanging portion of the crane. Equipped with a lifting device, an inverter for driving the turning motor, and a mechanism for generating a turning speed command given to the inverter in response to the turning angle command. A turning speed pattern that does not generate torsion at the end of turning is created in advance by a combination of and a constant speed motion, and the motor is driven by an inverter according to the pattern to perform turning, so that occurrence of a twist angle is minimized. Can be suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing the structure of a turning control crane.

FIG. 2 is a control block diagram.

3A and 3B show a first embodiment of a speed pattern. FIG. 3A is a speed pattern diagram for performing acceleration / deceleration in one natural period, and FIG. 3B is a phase plane locus diagram based on the speed pattern.

4A and 4B show a second embodiment of a speed pattern, FIG. 4A is a speed pattern diagram for performing acceleration / deceleration in a combination of a quarter of the natural period, and FIG. 4B is a phase plane locus diagram based on the speed pattern.

5A and 5B show a third embodiment of a speed pattern. FIG. 5A is a speed pattern diagram for performing acceleration / deceleration in a combination of 1/6 of the natural period, and FIG. 5B is a phase plane locus diagram based on the speed pattern.

[Explanation of symbols]

 Reference Signs List A crane 1 crane girder 2 club 3 hoist drum 4 wire rope 6 turning drive motor 8 turning mechanism 9 hanging tool 10 hook sheave 11 head sheave

Claims (1)

(57) [Claims] 1. A hoist provided with a turning mechanism driven by a motor between a hook sheave portion and a gripping portion for fixing a suspended load, a hoisting portion of the crane, an inverter driving the turning motor, and a turning angle command. To generate a turning speed command to be given to the inverter in response to the turning angle command, create a turning speed pattern that does not generate twist at the end of turning in advance in response to the turning angle command, drive the motor by the inverter, and minimize the occurrence of twist angle. A method for controlling the swinging posture of a suspended load of a crane, characterized in that the swing posture is controlled to a minimum.