JPH08319084A - Turning attitude control method for hanging load of crane - Google Patents

Abstract

PURPOSE: To attenuate harmful twisting oscillation developed for a short time when a hanging load is turned, and stably transport the hanging load with its attitude maintained in direction. CONSTITUTION: A turning device 8 to be driven by a motor is interposed between a hook sheave 10 of a crane A and a hoisting accessory 9. Twisting angle sensors 5 are provided, each of which detects a twisting angle of the hook sheave 10 with respect to the reference position of the crane A when a turning device 8 is driven, and also detects its twisting angular velocity. Furthermore, signals from the respective sensors 5 are inputted into a control device, and the motor 6 of the turning device is then driven by an inverter at a given speed, so that the hoisting accessory 9 and a hanging load are thereby rotated. Besides, the turning angle of the turning device 8 is detected by an encoder 7, and concurrently a twisting angle with respect to a turning speed is estimated based on characteristic frequency determined by the moment of inertia of the hanging load and the hoisting accessory 9 and the distance and length of a wire rope 4 and the like. Twisting is thereby controlled while the turning speed is being fed-back by using the aforesaid estimated twisting angle and the twisting angle measured by the twisting angle sensor 5 at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swinging posture of a suspended load of a crane, in which a twisting motion based on the swinging of the crane is attenuated in a short time when the crane is automatically operated and the suspended load is swung. It relates to a control method.

[0002]

2. Description of the Related Art Conventionally, in an automatic crane, when a suspended load is hung up and swung at a predetermined angle to be transported, a hanging tool and a suspended load hung by a wire are hung by the action of the reaction force at the time of the swing. It was difficult to stop the twisting motion of turning the load. For this reason, the winding wire is shortened as much as possible up to the upper limit of winding so that twisting does not occur with a long wire, and the wire is turned in a mechanically restrained state. During manual operation, the skill of the driver operated the turning motor to prevent twisting.

[0003]

When modifying an existing manually operated crane to an automatic operation, the existing equipment is used as a lifting tool for automatic operation due to dimensional restrictions of the crane and restrictions of hoisting load. Is desired. Regarding the suppression of swinging of the suspended load to achieve stable transport, the steady-state control can suppress the swinging of the suspended load during handling and transport it to the target position, but if a twisting motion occurs, Handling may fail. In addition, in the case of conveyance in which a turning motion is imparted and the direction of the suspended load is changed, unless proper control is performed, the handling must be interrupted until the twisting motion is attenuated, and a practical conveyance capacity cannot be realized.

It is an object of the present invention to attenuate this harmful twisting motion that occurs when a suspended load is turned in a short period of time, and to realize conveyance in which a stable suspended orientation is maintained.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and comprises a turning device driven by a motor between a hook sheave of a crane and a hoisting device. Equipped with a twist angle sensor that detects the twist angle of the hook sheave with respect to the crane reference position, and the twist angle sensor.The signals from these sensors are input to the control device, and the motor of the swing device is driven at an arbitrary speed by an inverter The rotation angle of the swing device is detected by the encoder, and the inertial moment between the load and the hanger and the natural frequency due to the distance and length of the wire rope hanging the load from The gist of the invention is to estimate the twist angle, and feedback control the turning speed based on the estimated twist value and the actual twist angle measured by the twist angle sensor to suppress the twist.

[0006]

[Operation] Gives a command for the turning angle. As a result, the turning speed command value is calculated, and turning is started. In this case, the gain of the proportional element is applied so as to make the estimated twist angle and angular velocity zero, and is added to the turning speed command value. As a result, the torsional vibration is reduced as much as possible, and the vehicle turns to the target angle.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for controlling a turning posture of a suspended load of a crane according to the present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 shows a mechanical configuration of a turning posture control device for a suspended load of a crane of the present invention. In the crane A shown in the figure, 1 is a girder of the crane, and 2 is a club traversing the crane girder 1. Then, the hoisting tool 9 is hung vertically by the wire rope 4 from the winding drum 3 and the head sheave 11 provided in the girder 2. The suspender 9 includes a hook sheave portion 10 and a turning device 8
And the lifting device 9 is rotated by the turning device 8 composed of gears and the like by the turning electric motor 6. The rotation angle of the turning device is detected by the encoder 7 provided in the turning device 8. A twist angle measuring sensor 5, for example, a gyro is installed at the center above the hook sheave 10, and the angle of twist with respect to the reference position (for example, the club 2) of the crane on the hook sheave 10 side is measured.

FIG. 2 is a control block diagram of the turning posture control device for the suspended load of the crane of the present invention. The swing posture control circuit B for the suspended load includes a swing angle command circuit C, a twist angle estimation calculation circuit D, an actual twist angle detection circuit E, and a drive circuit F for the swing motor 6. The turning electric motor 6 is an induction motor, the turning device 8 is rotated through the speed reducer 12, the rotation angle is detected by the encoder 7, and the rotation angle is applied to the turning angle command circuit C as a pulse signal.

In the turning posture control of the suspended load, a command signal for the swing angle θ of the suspended load is given as shown in FIG. That is, with this command signal, the time during which the signal is given is fixed to, for example, 1 second, and the angle θ is changed according to the magnitude of the amplitude.
The turning angle command circuit C includes a bypass circuit c1 and an integrating circuit c.
2. The calculation mechanism c3 is provided, and the turning angle command is applied to the adding circuit c4 via the bypass circuit c1. The integrating circuit c2 integrates the turning angle command to calculate the deviation of the actual rotation angle measured by the encoder 7. The circuit c3 performs proportional integration.
Here, the command value of the turning angle coincides with its integrated value, the deviation of the angle with respect to the turning target is proportionally integrated to follow the target angle, and the turning speed command is given via the rate limiter.

The rate limiter 13 differentiates the input signal and functions as a band limit of the output frequency that limits the value to a fixed value or less. The rate limiter 13 suppresses the output change in response to the input of the ramp signal so that the turning speed command reaches the maximum speed in approximately one cycle of twist.

The characteristics of the inverter and the characteristics of the load are the motor 6
The driving speed, the magnitude of the load, and the characteristics of the inverter are used to calculate the secondary delay or the primary delay to obtain the rotation speed of the turning. Usually, it can be approximated by a first-order delay having a time constant of about 0.2 to 0.4 seconds.

On the other hand, the twist angle detection circuit D detects the actual twist angle by the twist angle sensor (gyro 5), differentiates this twist angle with respect to time to detect the twist angular velocity, and amplifies these outputs to turn. Feedback control is performed by adding to the speed command value.

In this case, the twist angle and the angular velocity can be estimated in advance from the lifting weight, the length of the wire rope and the like. Therefore, it is preferable to control the turning speed by inputting this estimated value. Twist angle estimation The calculation procedure for the twist angle estimation in the calculation circuit C is as follows.
Assuming that the inertial moment J1 of the upper part, the inertial moment J2 of the lower part, the lifting load W, the wire length l, and the wire rope interval are r, the natural period ω of the twist is

[0014]

(Equation 1)

The twist angle can be estimated by the following equation. The twist angular velocity is obtained by differentiating the angle with respect to time. The estimated values of the twist angle and the angular velocity are fed back and added to the turning speed command, and the gain of the proportional element is applied so as to make the twist angle zero.

Although the moment of inertia of a suspended load cannot be directly measured, it is easily determined from the correlation between the load of the suspended load and the moment of inertia in applications where the shape of the transported object is limited, for example, applications such as steel coil transportation. The cycle can be calculated. 90
The results of the control of turning of the degree are shown in FIGS. 4, 5 and 6. FIG.
Indicates the error with respect to the target angle. FIG. 5 shows the turning speed. FIG. 6 shows the twist angle.

In the present embodiment, the example in which the twist angle is measured and controlled by the sensor (gyro 5) has been described. However, when the twist angle sensor cannot be used due to a failure or the like, an abnormal value occurs in the twist numerical value due to disturbance. At this time, malfunction can be prevented by controlling the turning speed based on the estimated value of the twist. Alternatively, in the temporary and simple operation of manual operation, the sensor may not be used and only the estimated value of the twist angle may be used to make a turn with a small twist. This corresponds to setting the twist angle sensor angle gain and the angular velocity gain in FIG. 2 to zero.

The present embodiment is effective in suppressing the motion (vibration phenomenon) that can be approximated by a simple vibration without being limited to the torsional vibration of the suspended load of the crane. For example, the control of the vibration of the load and the extension of the wire rope of the load can be performed. It can also be applied to the damping of vertical vibrations due to.
In this case, a deflection angle detection sensor or a vertical vibration velocity sensor may be prepared instead of the torsion angle sensor, and signal processing may be appropriately performed.

[0019]

As described above, according to the method for controlling the turning posture of the suspended load of the crane of the present invention, the twist angle with respect to the reference position of the crane of the turning device and the twist angular velocity are detected on the hook sheave side, and the hoisting by the turning device is performed. The turning angle between the tool and the suspended load is detected by the encoder, the twist angle with respect to the swivel speed is estimated from the moment of inertia of the suspended load and the hanging tool, and the estimated swirl speed feedback control the swivel speed to suppress the twist. Therefore, the suspended load can be swung smoothly without twisting. Further, according to the present invention, since the estimated value is used for controlling the twist angle, even if the twist angle sensor shows an abnormal value due to disturbance or the like, malfunction due to this does not occur.

[Brief description of drawings]

FIG. 1 is a front view showing a mechanical configuration of a turning posture control device for a suspended load of a crane according to the present invention.

FIG. 2 is a control block diagram of a method for controlling a turning posture of a suspended load of a crane according to the present invention.

FIG. 3 is a graph showing a turning angle command signal.

FIG. 4 is a graph showing the relationship between the time after the start of control and the position error.

FIG. 5 is a graph showing the relationship between the time after the start of control and the turning speed.

FIG. 6 is a graph showing the relationship between the time after the start of control and the twist angle.

[Explanation of symbols]

 A Crane 1 Crane girder 2 Club 4 Wire rope 5 Twist angle measurement sensor 6 Turning drive electric motor 7 Encoder 8 Turning mechanism 9 Lifting tool 10 Hook sheave

Claims (1)

[Claims] 1. A twisting angle sensor for detecting a twisting angle of a hooking sheave with respect to a reference position of a crane and a twisting angular velocity, comprising a turning device driven by a motor between a hook sheave of a crane and a hanger. By inputting the signal from each sensor to the control device, the motor of the turning device is driven at an arbitrary speed by the inverter to rotate the hanger and the suspended load, and the turning angle of the turning device is detected by the encoder. , The torsion angle with respect to the turning speed is estimated from the natural frequency due to the moment of inertia of the suspended load and the suspending equipment and the spacing and length of the wire rope that suspends the suspended load, and the estimated value of this torsion and the torsion measured by the torsion angle sensor. A method for controlling the turning attitude of a suspended load of a crane, characterized in that both are used together to feedback control the turning speed to suppress twisting.