JPS6219353B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for detecting the swing of a suspended load (or a load lifting device such as a hook) in a crane, and in particular utilizes the behavior of a movable pulley to which a hook is attached in an overhead traveling type crane. This paper proposes a highly accurate shake detection method.

Cranes that lift loads and transport them to desired positions tend to vibrate due to inertia during the acceleration and deceleration of the trolleys that move the loads after hoisting them. After the load has stopped, it is necessary to wait until the load stops vibrating before lowering the load, which not only impairs cargo handling efficiency, but also causes the heavy load to vibrate in a pendulum-like manner, creating an extremely dangerous situation and causing safety issues. There is. In addition, in order to suppress the swing of the suspended load as much as possible and stop the suspended load quickly and safely at a predetermined position, it is necessary to delicately adjust the moving speed of the trolley, and its operation requires a high level of skill. It's work.

In recent years, automatic operation of cranes has been promoted from the perspective of labor saving, but the biggest challenge is how to prevent the swing of the suspended load, and one solution is to detect the swing of the suspended load. It is conceivable to adjust and control the moving speed of the trolley based on this detection result, but the accuracy of this control depends on the accuracy of detecting the swing of the suspended load. By the way, as a method for detecting swinging of a suspended load, a method disclosed in Japanese Patent Publication No. 11857/1983 is known. This is to detect the amount of swing of the suspended load by detecting the swing angle of the rope as follows. That is, a swing detection rod whose upper end is rotatably supported in the direction of movement of the trolley is attached to the trolley of the crane, and the rope is passed through a horizontal ring formed at the lower end of the detection rod and has approximately the same inner diameter as the rope. This method detects the angle of swing of the detection rod accompanying this, and detects the swing angle of the rope based on this detection result. However, in this method, the position where the rope leaves the hoisting drum that suspends it (the rope fulcrum position) moves in the axial direction of the hoisting drum as the suspended load is hoisted or lowered due to the structure of the hoisting drum. The rope fulcrum position changes, and on the other hand, the rope fulcrum position and the pivot point of the detection rod must have different vertical positions, so the relationship between the rope inclination angle and the detection rod inclination angle is determined by the hoisting device. Therefore, this method has low detection accuracy and is not satisfactory as a shake detection method for automated crane operation.

The present invention has been made in view of the above circumstances, and in the control of preventing the hanging load of a crane from swinging,
It is an object of the present invention to provide a highly accurate method for detecting the swing of a suspended load, which makes it possible to improve the control accuracy.

The method for detecting swing of a crane suspended load according to the present invention includes:
A crane comprising a movable pulley with a load lifting device attached to a rope that hangs around a pair of hoisting drums placed a predetermined distance apart,
The rotation angle of the movable pulley and the hoisting drum from a predetermined state is measured, and the rotation angle of the movable pulley and the hoisting position of the movable pulley due to swinging of the suspended load are detected, and this detection result and the hoisting drum and movable pulley are measured. The radius of the hoisting drum and the distance between the hoisting drums are defined as the movable pulley position directly below the middle of both hoisting drums and the actual movement when the length of the rope from one hoisting drum via the movable pulley to the other hoisting drum is constant. The swing amount or swing speed of the suspended load is detected by applying it to a relational expression showing that the swing amount of the suspended load, defined as the horizontal distance from the pulley position, is proportional to the detected value of the rotation angle of the movable pulley. It is characterized by

The method of the present invention will be specifically explained below based on the drawings. Figure 1 is a schematic diagram of an overhead crane. Brackets 4, 4 are formed on the side walls near the ceiling of the factory building, and a pair of runways 3, 3 are laid on the brackets 4, 4 along the side walls. The runway 3 includes a runway girder 32 fixedly installed on a bracket 4 and a runway girder 3.
A pair of rails 31, 31 are arranged parallel to each other. The crane main body 2 is placed astride between the pair of runways 3, 3, and the main girder 2 of the crane main body 2
Wheels 23, 23 attached to saddles 22, 22 installed at both ends of the crane 1 are fitted to rails 31, 31, and rotation of the wheels 23, 23 driven by a traveling drive device (not shown) causes the crane main body to move. 2 is designed to be able to travel along the longitudinal direction of the building. On the other hand, a trolley 1 is placed on the main girder 21, and the trolley 1 has wheels 14, 14 driven by a traverse drive device (not shown).
Due to the rotation of the main girder 21, the main girder 21 is moved horizontally. A pair of hoisting drums 11 and 12 are installed on the trolley 1 in a transverse direction with their axes in the traveling direction of the crane body 2, and a rope 15 whose both ends are fixed to the hoisting drums 11 and 12 is A movable pulley 13 is suspended in the middle of the movable pulley 13, and a hook 16 is supported on the shaft of the movable pulley 13 to suspend a suspended load (not shown). An elevating drive device 17 (see FIG. 2) is connected to one of the hoisting drums 11 and 12 (for example, the hoisting drum 12), and by rotating the hoisting drum 12 in forward and reverse directions, the hoisting drum 12 is rotated. coiled rope 15
As the amount of winding increases or decreases, the length of the rope hanging between the hoisting drums 11 and 12 increases or decreases, making it possible to hoist or lower the movable pulley 13 or the suspended load suspended from the hook 16. can. Note that the winding drum 11 is fixed during normal operations.

As shown in FIG. 2, the hoisting drum 12 is equipped with a pulse generator 5 that emits one pulse each time the hoisting drum 12 rotates by a certain angle, depending on the direction of rotation.
1 is connected in motion, and its pulse output is input to the up-count terminal and down-count terminal of the up-down counter 61, respectively. The counter 61 adds the number of pulses corresponding to the rotation angle (or number of rotations) when the hoist drum 12 rotates to lower a suspended load, and conversely adds the number of pulses corresponding to the rotation angle (or rotation speed) when the hoist drum 12 rotates to hoist a suspended load. The addition/subtraction mode is switched so as to subtract the number of pulses corresponding to It is set to 0. Therefore, the count content of the counter 61 is the highest height position (upper limit position) of the movable pulley 13.
The contents of this count are input to the arithmetic circuit 63.
On the other hand, a similar pulse generator 52 is also connected to the movable pulley 13, and its output is input to an up-down counter 62. FIG. 5 shows an example of how the pulse generator 52 is attached to a movable pulley. One side of the frame 13a of the movable pulley rotatably supports the movable pulley 13 and suspends the hook 16. Pulse generator 5 on the outside
The fixed part 2 is fixed in such a way that its rotating shaft is parallel to the rotating shaft of the movable pulley 13, and the rotating shaft is operatively connected to the rotating shaft of the movable pulley 13 via a gear mechanism 52'. ing. Therefore, as the movable pulley 13 rotates, the rotating shaft portion of the pulse generator 52 rotates via the gear mechanism 52', and the rotation angle is measured by the number of output pulses. The counter 62 is configured to add or subtract the number of pulses depending on the rotation direction of the movable pulley 13. For example, when the movable pulley 13 swings toward the hoisting drum 12, the number of pulses generated due to the rotation accompanying the swing. is added, and conversely, when the winding drum swings toward the winding drum 11 side, the number of pulses generated due to the rotation accompanying the swing is subtracted. The count contents of the counter 62 are input to the arithmetic circuit 63. When the count content of the counter 61 is constant, that is, when the hoisting drum 12 is stopped, the counter 62 does not receive a pulse output from the pulse generator 52, and the count content changes over a predetermined period of time. When not rotating, that is, when the movable pulley 13 is not rotating, the count value is set to 0. In addition, instead of setting the count value of the counter 62 to 0 when it remains unchanged for a certain period of time, the counter 62 counts by inputting a clear signal that is manually issued when there is no vibration of the movable pulley 13. The content may be set to 0. The arithmetic circuit 63 calculates the movable pulley 1 from the count values input from the counter 61 and the counter 62.
3 or calculate the swing amount x and swing speed x of the suspended load.

The principle of calculating the above x and x〓 in the arithmetic circuit 63 and the contents of the calculation will be explained below. As shown in FIG. 2, point A is the point where the rope 15 leaves the hoisting drum 11, and point B is the point where the rope 15 leaves the hoisting drum 11.
Let it be the point away from. That is, points A and B are the rope fulcrums of the hoisting drums 11 and 12, respectively. Also point O
is the lower end position on the outer periphery of the movable pulley 13 when the suspended load is completely stationary, that is, when the movable pulley 13 is located directly below the center between the hoisting drums 11 and 12. Further, the radius of the rope winding surfaces of the hoisting drums 11 and 12 is R, the radius of the circumferential surface of the movable pulley 13 is r,
Also, the distance between the centers of both winding drums 11 and 12 is set to 2.
s, and the vertical distance between the hoisting drums 11, 12 and the center of the movable pulley 13 is h, the geometric relationship between points A, B, and O can be expressed as shown in FIG. In other words, the magnitude relationship of 2s, R, and r is (2s or h)
≫(R or r), so the distance between points A and B is 2
(s+R), the vertical distance between point A or B and point O is (h
+r), and furthermore, the rope 15
The geometric position of (see FIG. 2) can be approximated and represented by a straight line connecting points A and O and points B and O. If the movable pulley 13 swings toward the hoisting drum 11 and the lower end position on the outer circumference of the movable pulley 13 moves to point P when the rotation of the hoisting drum 12 is stopped, then from the above-mentioned size relationship, the rope fulcrum A , B do not change, the geometrical position of the rope 15 can be expressed as shown by the broken line in FIG. In this case, the rope length + is equal to the rope length + when the movable pulley 13 is located directly below the center between both the hoisting drums 11 and 12, so the rope length + is the same as the rope length + when the movable pulley 13 is located directly below the center between the hoisting drums 11 and 12. Considering an x-y orthogonal coordinate system with the x-axis and the y-axis pointing vertically upward, the coordinates of point P are P(x,
y), then +=+, so
The following formula (1) holds true.

2√(+) ² +(+) ² =√(+-) ² +(++) ² +√(+-) ² +(+-) ² ...(1) According to Taylor expansion, generally a≪1 When √1
±a〓1±1/2a. Assuming that the swing of the movable pulley 13 is relatively small, x≫y, (h+r)≫x
Since it can be considered that (S+R)≫y, the above approximate formula can be written as (1)
When used to simplify the first and second terms on the right side of the equation, we end up with
Equation (1) is transformed as shown in Equation (2) below.

x ² -2(h+r)y=0 ...(2) On the other hand, the movable pulley 13 swings from the stopped state toward the hoisting drum 11, and the lower end position of its outer circumference changes from point O to point P.
The rotation angle θ of the movable pulley 13 when it moves in the direction (x, y) is expressed by the following equation (3).

rθ=√(+−) ² +(++) ² −√(+) ² +(+) ² ...(3) Equation (3) is transformed from equation (1) to equation (2), and the following equation Approximate transformation is performed as shown in equation (4).

By substituting equation (2) into equation (4), the following equation (5) is obtained.

x=rθ√(+) ² +(+) ² /(s+
R) ...(5) In other words, the amount of deflection x is the movement of the intermediate droop of both hoisting drums 11 and 12 when the length of the rope from one hoisting drum to the other hoisting drum via the movable pulley 13 is constant. It is defined as the horizontal distance between the position of the pulley 13 (origin O) and the actual position P of the movable pulley 13, and this amount of deflection x is proportional to the rotation angle θ of the movable pulley 13 as expressed by equation (5). Therefore, it can be found.

Further, h is expressed by the following equation (6) using the rope length 2l (=+).

h=√ ² −(+) ² −r ...(6) In formulas (5) and (6), s, R, and r are constants,
θ and l are determined based on the integrated contents of the counters 61 and 62 as shown in the following equations (7) and (8).

θ=2πN ₂ /n ₂ ...(7) l=l ₀ /2+2πRN ₁ /n ₁ ...(8) However, N ₁ , N ₂ : Count values of counters 61, 62 respectively n ₁ , n ₂ : respectively Each time the hoisting drum 12 or movable pulley 13 makes one rotation, the pulse generators 51 and 52
Number of pulses emitted by l ₀ : Length of the rope between both hoisting drums 11 and 12 when the movable pulley 13 is hoisted to its maximum height position Substitute equations (6), (7), and (8) into equation (5) Then, the following equation (9) is obtained, x=2πrN ₂ /n ₂ (s+R)・(l ₀ /2+2πR
N ₁ /n ₁ )...(9) The arithmetic circuit 63 calculates the counted values of the counters 61 and 62.
Using N ₁ , N ₂ and preset constants s, R, r, and n ₁ , n ₂ , l ₀ , move the movable pulley 1 according to equation (9).
3, the swing amount x of the suspended load is calculated. As mentioned above, N ₂ is a positive value when the movable pulley 13 swings toward the hoisting drum 12 side, and a negative value when the movable pulley 13 swings toward the hoisting drum 11 side. If it is located directly below the center between 12, it will be 0, so x found from equation (9)
corresponds to a positive value, a negative value, or 0. The arithmetic circuit 63 further determines the amount of change x in x per unit time, that is, the swing speed x of the suspended load or movable pulley 13.

As described above, when the trolley 1 travels horizontally and the suspended load swings in the horizontal direction due to the inertia caused by its acceleration and deceleration, the rotation angle of the movable pulley 13 is counted by the pulse output of the pulse generator 13 by the counter 62. The winding position of the movable pulley 13 is determined by
The pulse output of 2 is detected by counting with a counter 61, and a calculation is performed in an arithmetic circuit 63 based on the count contents of the counters 61 and 62 to calculate the swing amount x of the movable pulley 13, that is, the suspended load, Also, the swing speed x is calculated. The data regarding the amount of swing x and the swing speed x obtained in this way is input to an operation control device (not shown) that controls automatic operation of the crane and is provided as data for steady rest control. However, the detection accuracy of x and x〓 is extremely high, and precise steady rest control is possible. Fourth
Figures a and b are x and x recorded on the recorder, respectively.
The horizontal axis is time, and the vertical axis is a
is x (mm), and b is x〓 (mm/sec). Note that the constants such as s and R when obtaining this detection result are as follows.

s=1.2m, h=10m, R=0.18m, r=0.15
m, n ₁ = 360 pulses, n ₂ = 360 pulses As is clear from Figure 4 a and b, the damped vibration when the suspended load swings is very clearly captured, and the swing amount x and swing speed x It can be seen that the detection accuracy of 〓 is high.

As detailed above, in the case of the method of the present invention, the rotation angle of the movable pulley and the hoisting drum from a predetermined state is measured to detect the rotation angle of the movable pulley and the hoisting device of the movable pulley due to the swinging of the suspended load, This detection result, the radius of the hoisting drum and movable pulley, and the distance between the hoisting drums are calculated using the following equation: The amount of swing of the suspended load, defined as the horizontal distance between the movable pulley position immediately below the intermediate position and the actual movable pulley position, is proportional to the detected value of the rotation angle of the movable pulley. Since the amount or speed of swing of the load is detected, the detection accuracy of the amount and speed of swing is extremely high, and when used in a steady rest control system, a system with extremely high control accuracy can be constructed. The invention has a great effect on improving crane automatic operation technology.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of an overhead crane, Figure 2 is a schematic diagram of the equipment used to implement the method of the present invention, Figure 3 is an explanatory diagram of the principle of calculating the amount of runout, and Figure 4 is the effect of the method of the present invention. FIG. 5 is a vertical sectional view showing how the pulse generator 52 is installed. 1... Traveling part, 2... Crane main body, 3... Runway, 11, 12... Hoisting drum, 13...
...Moving pulley, 15...Rope, 51, 52...Pulse generator, 61, 62...Counter, 63
...Arithmetic circuit.

Claims (1)

[Scope of Claims] 1. A crane comprising a movable pulley with a load lifting device attached to a rope that is wound around a pair of hoisting drums arranged a predetermined distance apart and hanging down, the movable pulley and The rotation angle of the hoisting drum from a predetermined state is measured to detect the rotation angle of the movable pulley and the hoisting position of the movable pulley due to the swinging of the suspended load, and based on this detection result, the radius of the hoisting drum and movable pulley, and the hoisting drum. The horizontal distance between the movable pulley position directly below the middle of both hoisting drums and the actual movable pulley position when the length of the rope from one hoisting drum via the movable pulley to the other hoisting drum is constant. A crane characterized in that the swing amount or swing speed of the suspended load is detected by applying it to a relational expression showing that the swing amount of the suspended load defined as a distance is proportional to the detected rotation angle value of the movable pulley. Method for detecting swing of a suspended load.