JPH1160153A - Swing angle measuring device for hoisted load on crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a swing angle measuring device which is accurate, is high reliable, and is used for a hoisted load on a crane, by using acceleration information for hoisted load which is measured by a first accelerometer and trolley's acceleration information which is measured by a second accelerometer, and estimating swing angle and angular velocity of a hoisted load using an observer operation method. SOLUTION: A first accelerometer 1 is fixed to a hoisting accessory 6 for a hoisted load 8 with screws or the like and measures acceleration information for the hoisted load, and a second accelerometer 2 is fixed to a trolley 7 with screws or the like and measures trolley's acceleration information. Output signals from the first accelerometer 1 and the second accelerometer 2 are transmitted to an operation device 3 through a first communication wire 4 and a second communication wire 5, respectively. The operation device 3 employs an observer operation method and can estimate angle of the hoisted load 8 from the vertical direction and its angular velocity. Therefore, a swing angle measuring device which is accurate, is high reliable, and is used for the hoisted load on a crane can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a swing angle of a suspended load from a vertical direction when the load is suspended by a crane or the like. In particular, the present invention relates to an apparatus for measuring a swing angle of a suspended load capable of performing accurate measurement by using an accelerometer and an arithmetic unit.

[0002]

2. Description of the Related Art In a crane, when a suspended load is hoisted, or when the crane traverses or runs, the suspended load swings. In particular, when a suspended load is transported by an automatic crane and the suspended load is accurately landed at a desired position, it is necessary to detect the swing of the suspended load and perform control to suppress the swing. Conventionally, when a load is hung by a crane or the like, the deflection angle of the load from the vertical direction is measured by an inclinometer, image processing, or the like. There were the following problems.

(1) In the inclinometer, the object to be measured is not a suspended load but a rope. Therefore, when the rope has a bend or a bend, an error becomes large. Also, when a plurality of ropes are hung, measurement cannot be performed correctly. (2) Image processing is easily affected by natural environments such as snow. In addition, the target may be erroneously recognized. At this time, there is a high risk, and it is difficult to recognize the correct target. In addition, image processing devices are very expensive. (3) In the case of measurement using an accelerometer, the following problems exist, and correct values cannot be obtained unless these problems are solved. That is, the accelerometer is subjected to an acceleration obtained by adding the acceleration due to the motion of the attached object and the gravitational acceleration component according to the tilt, but these cannot be separately measured. If a gyro is used together, it is possible to perform an operation to separate them, but the cost of the apparatus is high. (4) When an angle or the like is obtained using an accelerometer, disturbance or measurement error received due to wind, vibration, or the like accumulates with time in a method of simply integrating acceleration information.

[0004]

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an accurate and highly reliable swing angle measuring apparatus for a crane using a accelerometer and an arithmetic unit. That is the task.

[0005]

According to the present invention, there is provided an apparatus for measuring the swing angle of a suspended load of a crane according to the present invention, wherein acceleration information of a suspended load measured by a first accelerometer attached to a lifting device is used in the crane. The swing angle and the angular velocity of the suspended load from the vertical direction are estimated by using an observer calculation method using acceleration information of the trolley measured by the second accelerometer attached to the trolley. Instead of the trolley acceleration information measured by the second accelerometer attached to the trolley, the trolley speed measured by the motor tachometer, the command value to the motor controller, or the motor Any information such as a command value to the drive unit such as a command value to the motor or a driving force such as a motor voltage or current may be used.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the apparatus of the present invention will be described with reference to FIG. The apparatus shown in FIG. 1 includes a first accelerometer 1, a second accelerometer 2, and an arithmetic unit 3. The first accelerometer 1 is fixed to the hanging member 6 of the hanging load 8 with a screw or the like. The second accelerometer 2 is fixed to a trolley (hereinafter referred to as a trolley) 7 with screws or the like. Output signals of the first accelerometer 1 and the second accelerometer 2 are transmitted to the arithmetic unit 3 via the first communication line 4 and the second communication line 5, respectively. The arithmetic unit 3 employs an observer arithmetic method having the structure shown in FIG. 2 (see "Basics and Application of Control Theory" by Umaki and Akashi, published by Ohmsha in 1986).
Thereby, the angle and angular velocity of the suspended load 8 from the vertical direction can be estimated from the information of the first accelerometer 1 and the second accelerometer 2.

[0007] Incidentally, an observer is an arithmetic technique for estimating the state of a controlled object using its model. In general, since an actual controlled object cannot be completely modeled, even if the same input as the controlled object is given to the model, the state of the controlled object cannot be known from the state of the model. A system that estimates while correcting the state by using the difference between the output of the control target and the output of the model for the same input is called an observer.

Hereinafter, the observer will be schematically described with reference to FIG. The dynamic characteristic is as follows:

[0009]

(Equation 1)

The structure of the observer will be described with reference to FIG. The inside of the dotted line in the upper part of FIG. 3 is the control target, and the inside of the dotted line in the lower part is the system model.

[0011]

(Equation 2)

[0012]

(Equation 3)

[0013]

(Equation 4)

[0014]

(Equation 5)

The observer in the present invention is shown in FIG.
The configuration is as shown in FIG. From the first communication line 4 for transmitting the output signal of the first accelerometer 1 and the second communication line 5 for transmitting the output signal of the second accelerometer 2, signals from the first accelerometer 1 and the second An acceleration signal is output. The inputs to the integrator 9 are the acceleration signals transmitted from the first and second accelerometers 1 and 2 via the first communication line 4 and the second communication line 5, and the output of the integrator 9, respectively. As shown in FIG. 2, appropriate gains B and E and (A-E)
It is calculated by multiplying by C) and then adding. Each gain is obtained as described below. Thus, the output of the integrator 9 becomes the estimated value of the angle, angular velocity and disturbance.

[0016]

(Equation 6)

If u (t) = [trolley driving force] and y (t) = [suspension of load], these relations can be expressed by the following mathematical expressions.

[0018]

(Equation 7)

If the crane is a traversing crane having a loop length l, A, B, and C are respectively defined using a constant δ determined by the crane and a gravitational acceleration g.

[0020]

(Equation 8)

By expressing the crane as a mathematical expression in this manner, a state estimating mechanism serving as the observer can be designed. The use of this observer can prevent accumulation of measurement errors and disturbances caused by a method of simply integrating acceleration information. In actual measurement, the following problems may occur. (1) The swing varies depending on the length of the rope, the manner of hanging the rope, the state of the load, and the like. (2) Only the acceleration of the suspended load cannot be correctly measured. As a problem due to the fact that the accelerometer measures a value obtained by adding two values of the acceleration caused by the swing of the suspended load and the component of the gravitational acceleration according to the inclination of the suspended load, there are the following problems. (2-1) Steady inclination due to load imbalance. (2-2) An inclination caused by swing caused by hanging a plurality of ropes. (3) The driving force u (t) of the trolley cannot be measured.

These problems are A, B, C and x
(t), y (t) and u (t) are set as follows, respectively.
The problem is solved by designing an observer.

(1) The length of the rope, the method of applying the rope,
The problem of how the load changes depending on the load condition When the length of the rope changes, the period of the change changes. Therefore, unless a model having an appropriate loop length is used (unless A, B, and C are set appropriately), correct estimation cannot be performed.
For accurate estimation, A,
Obtain B and C and design an observer. A function or correspondence table of the relationship between the parameters of the observer and the loop length is obtained and used (see the correspondence table between the loop length and the gain in FIG. 4).

Further, the swinging manner changes even when a plurality of ropes hang. Furthermore, the swinging method changes depending on the presence or absence of a suspended load and the change in the center of gravity. The change in the swing is mainly reflected in the cycle. Therefore, approximation is made using a single pendulum crane model having the same period. A function or correspondence table is obtained and used for this relationship (see the table of the loop length having the same swing period in FIG. 5).

(2-1) Problem caused by tilting due to load imbalance A stationary disturbance such as a suspended load tilting due to load imbalance or an offset in the accelerometer itself is estimated by the disturbance. By adopting a technique of doing so, adverse effects can be suppressed. Specifically, the amount of disturbance is added to the element of x (t). As a result,

[0026]

(Equation 9)

(2-2) Inclination in accordance with run-out caused by hanging a plurality of ropes When a suspended load is hung by a plurality of ropes, the load is tilted according to the run-out (see FIG. 6). Therefore, not only the acceleration due to the motion of the suspended load, but also the component of the gravitational acceleration according to the inclination is measured by the accelerometer. A function or correspondence table of the relationship between the gravitational acceleration component and the shake angle is obtained and used (see FIG. 7).

For example, in the case of FIG. 7, C = (0−
By setting 1.8 001), y (t) = [acceleration due to motion] + [gravity acceleration according to shake] + [offset] = [accelerometer output value].

(3) Regarding the problem that the driving force u (t) of the trolley cannot be measured If u (t) and y (t) are set to independent quantities, a similar design can be made by variable conversion. is there. Among the quantities independent of y (t), the acceleration of the trolley, the speed of the trolley, the command value to the trolley drive unit, and the like can be measured and used as u (t). If u (t) = [trolley acceleration], A, B,
C is converted as follows.

[0030]

(Equation 10)

[0031]

[Equation 11]

When an observer is designed for A, B, and C obtained as described above, the gain E of the observer is obtained as a value that changes according to the loop length. FIG. 8 shows this correspondence.

(Operation) The operation as described above will be described below. Acceleration information is measured by the first accelerometer 1 and the second accelerometer 2 in accordance with the swing of the hanging device 6 and the movement of the trolley 7. This acceleration information is transmitted to the arithmetic unit 3 via the first communication line 4 and the second communication line 5. In the arithmetic unit 3, the angle and angular velocity of the suspended load 8 from the vertical direction are calculated by the observer using the acceleration information.
The observer contains a model of the movement of the crane inside, and even if an error or disturbance is included in the measured value, estimation is performed while correcting the value by feedback. In addition, the model of the observer considers that the measured value of the first accelerometer 1 includes two factors, the acceleration due to the movement of the hanging device 6 and the gravitational acceleration due to the inclination of the hanging device 6. There is no adverse effect due to the inability to separate the two types of acceleration.

(Embodiment 2) The basic configuration of the present apparatus is the same as that of the above-mentioned Embodiment 1, but it is possible to know any one of the speed of the trolley 7, the command value to the drive unit, and the drive force. If possible, it is possible to estimate the angle and the angular velocity only by the first accelerometer 1 attached to the hanging device 6. At this time, the second accelerometer 2 is unnecessary, and the second communication line 5 is arranged so as to connect the alternative measuring point to the arithmetic unit. When the command value to the trolley drive motor is known, the signal from the first accelerometer 1 and the command value to the drive unit of the trolley 7 are transmitted via the first communication line 4 and the second communication line 5, respectively. It is transmitted to the arithmetic unit 3. The arithmetic unit 3 estimates an angle and an angular velocity from information and a command value of the first accelerometer 1 using an observer.
The structure of the observer is the same as that of the first embodiment shown in FIG. 3, except for the parameters. The parameters are set in the first embodiment.
Can be performed according to

[0035]

According to the present invention, the crane utilizes the acceleration information of the suspended load by the first accelerometer attached to the hanging device and the trolley acceleration information by the second accelerometer attached to the trolley. -The deflection angle of the suspended load from the vertical direction was measured using the bar calculation method. As described above, the observer contains a model of the movement of the crane inside, and even if the measurement value includes an error or disturbance, estimation can be performed while correcting the value by feedback. it can. The model of the observer also includes the measured value of the first accelerometer 1 and the acceleration due to the motion of
It is taken into account that two types of gravitational acceleration due to the inclination are included, so that there is no adverse effect due to the inability to separate the two types of acceleration, and the accuracy is extremely high in accuracy. Alternatively, in place of the second acceleration information attached to the trolley, the speed of the trolley determined by the tachometer of the motor, the command value to the motor controller, the command value to the motor, etc. Since the information is either the command value to the drive unit or the drive force such as the motor voltage or current, the swing angle of the crane's suspended load is accurate and highly reliable by the accelerometer and the arithmetic unit. It became possible to obtain a measuring device.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration of a deflection angle measuring device according to the present invention.

FIG. 2 is a configuration diagram of an observer of the present invention.

FIG. 3 is a diagram illustrating the configuration of a general observer.

FIG. 4 is a graph showing a correspondence between a loop length and an observer gain.

FIG. 5 is a graph showing a relationship between a loop length and a single pendulum loop length having the same swing period.

FIG. 6 is a view showing an assumed inclination of a suspended load.

FIG. 7 is a graph showing a correspondence between a shake angle and a dynamic acceleration.

FIG. 8 is a graph showing a relationship between a loop length and an observer gain.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 First accelerometer 2 Second accelerometer 3 Arithmetic unit 4 First communication line 5 Second communication line 6 Hanging tool 7 Trolley 8 Hanging load 9 Integrator

Claims (2)

[Claims] In a crane, acceleration information of a suspended load measured by a first accelerometer attached to a suspending device;
A crane characterized by estimating a swing angle and an angular velocity of a suspended load from a vertical direction using an observer calculation method using acceleration information of the trolley measured by a second accelerometer attached to the trolley. For measuring the swing angle of suspended loads. 2. A trolley speed measured by a motor tachometer, a command value to a motor controller or a command value to a motor controller instead of the trolley acceleration information measured by a second accelerometer attached to the trolley. 2. A crane as claimed in claim 1, wherein said information is a command value to said drive unit such as a command value to said motor or a driving force such as voltage or current of said motor. A swing angle measuring device for suspended loads.