JP4155785B2 - Method for controlling steady rest of suspended load - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a suspended load steadying control method, and more particularly to a suspended load steadying control method capable of effectively reducing the swing of a crane suspended load with a simple device configuration.
[0002]
[Prior art]
FIG. 7 shows a crane of a type that travels by lifting a suspended load with a traversing trolley, and the crane 1 travels along a rail 3 by a traveling wheel 2 driven by a traveling motor M1. The crane 1 is provided with a winch drum 6 that is driven by a hoisting motor M <b> 2 and lifts and lowers a suspended load 5 via a rope 4.
[0003]
When the crane 1 in FIG. 7 starts traveling in the direction of the arrow with the suspended load 5 suspended, the suspended load 5 is delayed backward as shown by the broken line due to inertia, and the suspended load 5 generates a swing. Further, when the crane 1 traveling at a predetermined speed is decelerated and stopped, the suspended load 5 moves forward as shown by a two-dot chain line due to inertia, and the suspended load 5 generates a swing due to this. . This swing is caused by a gravity spring due to inertia acting on the suspended load 5, and such a swing of the suspended load 5 is a factor that impairs workability and safety in the cargo handling operation of the crane 1.
[0004]
Conventionally, various methods have been proposed in order to stop such a swing of the suspended load. For example, a method of accelerating or decelerating the crane speed in steps to reduce the swing width of the suspended load, a method of detecting the swing of the suspended load and controlling the acceleration or deceleration of the crane to reduce the swing, There is a method of controlling acceleration or deceleration so that the gravity spring is eliminated when a gravity spring of a certain value or more acts on the suspension load. And all of the above-described suspension of the suspended load is performed by feedback control.
[0005]
Such an anti-swaying method using feedback control has a problem that equipment is expensive because special sensors are required, and there is a problem that the detection accuracy of the sensors greatly affects the anti-sway effect.
[0006]
For this reason, in recent years, the crane is started from a stopped state in synchronization with one cycle of the suspended load's swing cycle and accelerated at a constant acceleration to a predetermined speed, and the crane is moved in one cycle of the suspended load's swing cycle. A method has been proposed in which a constant deceleration to a predetermined speed is performed to prevent the swing of a suspended load from being fed forward (for example, Patent Document 1).
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-095477
[Problems to be solved by the invention]
However, the steadying method disclosed in the above publication is controlled on the assumption that the suspended load swings during acceleration and deceleration of the crane. However, once a shake occurs in this way, there is a problem that it is difficult to reliably prevent the shake even if the crane is accelerated or decelerated in synchronization with one cycle of the shake.
[0009]
The present invention has been made by paying attention to the problems existing in the prior art as described above, and the object is to prevent a suspended load from swinging during acceleration and deceleration of the crane with a simple device configuration. Thus, an object of the present invention is to provide a suspension control method for a suspended load that enables simple stabilization.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, when the crane is accelerated, linear acceleration is performed from the travel start point to the set travel speed, and the pendulum whose travel start point is the dead point moves to the lowest point. And calculating a downward displacement distance and a quarter period of the pendulum in advance ,
On the other hand, when the traveling crane stops, linear deceleration is performed from the deceleration start point of the traveling speed to the stop point, and the upward displacement distance when the pendulum with the deceleration start point as the lowest point moves to the dead point, Calculate the 1/4 period of the pendulum in advance ,
When accelerating the crane, the linear acceleration time of the crane is made to coincide with the time of a quarter cycle of the pendulum, and simultaneously with the start of acceleration, the suspended load is unwound by the downward displacement distance within the time of a quarter cycle of the pendulum ,
On the other hand, when stopping the crane, rolling up the upward displacement distance suspended load linear deceleration time of the crane in a time of 1/4 period of the start and at the same time pendulum matched allowed and deceleration time of 1/4 period of the pendulum The present invention relates to a steady-state control method for a suspended load.
[0012]
According to the above means, it operates as follows.
[0013]
In the present invention, when accelerating the crane, the linear acceleration time of the crane is made to coincide with the 1/4 period of the pendulum, and the suspended load is wound by the downward displacement distance within the 1/4 period of the pendulum simultaneously with the start of the acceleration. By lowering the gravity spring of the suspended load by lowering, when the crane is stopped, the linear deceleration time of the crane is made coincident with the time of 1/4 period of the pendulum, and at the same time as the start of deceleration, the time of 1/4 period of the pendulum Since the suspended load is lifted by the upward displacement distance in the interior, the gravity spring of the suspended load is offset, so that the suspended load can be prevented from shaking when the crane is accelerated and stopped. Therefore, effective suspension of suspended loads can be achieved with a simple apparatus configuration by feedforward control.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.
[0016]
FIG. 1 and FIG. 2 show an example of a case where the suspension load steadying control method of the present invention is applied to a traversing trolley. FIG. 1 is an explanatory view showing the operation of the crane during acceleration, and FIG. FIG. 8 is an explanatory diagram showing the operation at the time of stopping, in which the same parts as those in FIG.
[0017]
As shown in FIGS. 1 and 2, the hoisting motor M <b> 2 provided in the crane 1 is provided with a hoisting detection device 7 composed of a rotary encoder or the like, and the hoisting detection device 7 detects the lifting height L of the suspended load 5. I am doing so. Various methods other than the illustrated example can also be adopted for detecting the suspension height L of the suspended load 5.
[0018]
Driving of the traveling motor M1 and the hoisting motor M2 of the crane 1 is controlled by control signals S1 and S2 from the control device 8.
[0019]
The control device 8 includes an arithmetic device 9 shown in the block diagram of FIG. 3, and the arithmetic device 9 includes a traveling speed V ₁ (set constant speed) of the crane 1 and a suspended load detected by the hoisting detection device 7. A suspension height L of 5 is input.
[0020]
As shown in FIG. 1A, the arithmetic unit 9 controls linear acceleration (constant acceleration) from the traveling start point (speed V ₀ ) to the traveling speed V ₁ during the acceleration of the crane. As shown in FIG. 1B, a downward displacement distance Δh that is a gravity spring when the pendulum whose dead center R ₀ is the position of the suspended load 5 at the starting point of acceleration moves to the lowest point R ₁ during acceleration. ₁ and a quarter period of the pendulum period T, that is, T / 4 are calculated in advance.
[0021]
Further, in order to cancel the downward displacement distance Δh ₁ that is the gravity spring, the suspended load 5 is controlled to be lowered during the linear acceleration, and the lowering speed Vvm ₁ at this time is obtained.
[0022]
The downward displacement distance Δh ₁ is obtained from the potential energy U and the kinetic energy K when the suspended load 5 moves to the lowest point R ₁ of the pendulum with the travel start point as the dead point R ₀ . That is,
U = mGh
K = 1 / 2mV ₁ ²
Therefore, by setting U = K, the downward displacement distance Δh ₁ is given by
Δh ₁ = V ₁ ² / 2G (1)
It is.
[0023]
The angular velocity ω is given by
ω = √ {G / (L + Δh ₁ )} (2)
Therefore, the period T is
T = 2π / ω (3)
It is.
[0024]
Furthermore, in order to cancel the downward displacement distance Δh ₁ which is a gravity spring, the lowering speed Vvm _{1 for} lowering the suspended load 5 during linear acceleration is given by
Vvm ₁ = 8Δh ₁ / T (4)
It is. Further, the lowering acceleration αv ₁ at this time is αv ₁ = ± 64Δh ₁ / T ² . A + sign indicates downward, and a-sign indicates upward.
[0025]
The horizontal acceleration α _h at this time is
α _h = 4V ₁ / T (5)
Therefore, the speed v during linear acceleration is
v = α _h t (6)
It becomes.
[0026]
On the other hand, as shown in FIG. 2A, the arithmetic unit 9 controls linear deceleration (constant deceleration) from the deceleration start point to the stop point of the traveling speed V ₁ when the traveling crane 1 is stopped. Further, as shown in FIG. 2 (B), it is a gravity spring when the pendulum moves to the dead point F ₀ with the deceleration start point at the time of stop as the lowest point F ₁ of the suspended load 5. An upward displacement distance Δh ₂ and a quarter period of the pendulum period T, that is, T / 4 are calculated in advance.
[0027]
Further, in order to cancel the upward displacement distance Δh ₂ that is the gravity spring, the suspended load 5 is hoisted during the linear deceleration, and the hoisting speed Vvm ₂ at this time is obtained.
[0028]
The upward displacement distance Δh ₂ is obtained from the potential energy U and kinetic energy K when the suspended load 5 moves to the pendulum dead center F ₀ with the deceleration start point as the lowest point F ₁ . That is,
U = mGh
K = 1 / 2mV ₁ ²
Therefore, by setting U = K, the upward displacement distance Δh ₂ is given by
Δh ₂ = V ₁ ² / 2G (7)
It is.
[0029]
Also, the angular velocity ω is
ω = √ (G / L) (8)
And the period T is
T = 2π / ω (9)
It is.
[0030]
Furthermore, in order to cancel the upward displacement distance Δh ₂ that is a gravity spring, the hoisting speed Vvm _{2 for} hoisting the suspended load 5 during linear deceleration is given by
Vvm ₂ = 8Δh ₂ / T (10)
It is. Further, the winding acceleration αv ₂ at this time is αv ₂ = ± 64Δh ₂ / T ² . A + sign indicates downward, and a-sign indicates upward.
[0031]
The horizontal deceleration rate α _h at this time is
α _h = 4V ₁ / T (11)
Therefore, the speed v ′ at the time of linear deceleration is given by
v ′ = V ₁ −α _h t (12)
It becomes.
[0032]
The arithmetic unit 9 in FIG. 3 stores the result of the above arithmetic operation, and controls the traveling of the crane 1 by outputting a control signal S1 to the traveling motor M1 via the inverter device 10 when the crane 1 is accelerated and stopped. The control signal S2 is output to the hoisting motor M2, and the hoisting and lowering of the suspended load 5 is controlled.
[0033]
Next, a steady-state control method during acceleration of the crane 1 will be described with reference to FIGS.
[0034]
During acceleration of the crane 1, as shown in FIG. 1 (A), the traveling motors M1 to running start point to the traveling speed V ₁ is set to (velocity = 0) (accelerated at a constant rate of change) linear accelerator At this time, the traveling is controlled so that the linear acceleration time t of the crane 1 is accelerated in accordance with T / 4, which is ¼ of the period T of the pendulum previously obtained by the arithmetic unit 9.
[0035]
Further, simultaneously with the start of the acceleration, the suspended load 5 is unwound by the downward displacement distance Δh ₁ obtained by the arithmetic unit 9 within the time T / 4 of the quarter period of the pendulum. At this time, the suspended load 5 is lowered at the lowering speed Vvm ₁ . In this way, when the suspended load 5 is lowered by the downward displacement distance Δh ₁ within the time T / 4 of the quarter period of the pendulum, the suspended load 5 starts from the dead point R ₀ as shown by the broken line in FIG. Since it moves to the lowest point R ₁ , the gravity spring cancels out, thereby eliminating the problem that the suspended load 5 swings during acceleration.
[0036]
When the traveling speed V ₁ of the crane 1 is 1 m / s and L is 10 m, the downward displacement distance Δh ₁ , the period T, and the lowering speed Vvm ₁ at the downward displacement distance Δh ₁ are expressed by the above equation (1). -It calculated | required using Formula (4).
Downward displacement distance Δh ₁ = 1 / (2 × 9.8) = 0.051 m
Angular velocity ω = √ {9.8 / (10 + 0.051)} = 0.987 rad / s
Period T = 2π / 0.987 = 6.36 s
Lowering speed Vvm ₁ = 8 × 0.051 / 6.36 = 0.064 m / s
[0037]
As described above, when the crane 1 is accelerated, linear acceleration is performed in accordance with the time of a quarter period of the pendulum, and at the same time, the suspended load 5 is moved by the downward displacement distance Δh ₁ within the time of the quarter period of the pendulum. By lowering, the gravity spring of the pendulum generated by acceleration cancels out and the suspended load 5 does not swing, so that the crane can move to the traveling speed V ₁ without the suspended load 5 swinging.
[0038]
Next, a description will be given of a steady-state control method when the crane 1 traveling at the traveling speed V ₁ is stopped with reference to FIGS.
[0039]
When the crane 1 traveling at the traveling speed V ₁ is stopped, as shown in FIG. 2A, linear deceleration (constant) from the deceleration start point (speed = V ₁ ) to the stop point (speed = V ₀ ) is performed. The traveling motor M1 is controlled so as to decelerate at a change rate. At this time, control is performed so that the linear deceleration time t of the crane 1 is decelerated in accordance with the time of a quarter period of the pendulum previously obtained by the arithmetic unit 9.
[0040]
Further, simultaneously with the start of the deceleration, the suspended load 5 is wound up by the upward displacement distance Δh ₂ obtained by the arithmetic unit 9 within the time of a quarter period of the pendulum. In this way, when the suspended load 5 is wound up by the upward displacement distance Δh ₂ within the time T / 4 of the quarter period of the pendulum, the suspended load 5 starts from the lowest point F ₁ as shown by the broken line in FIG. Since the gravity spring is moved to the dead point F ₀ , the gravity spring cancels out, thereby preventing the problem that the suspended load 5 swings during deceleration.
[0041]
When the traveling speed V _{1 of the} crane is 1 m / s and L is 10 m, the upward displacement distance Δh ₂ , the period T, and the hoisting speed Vvm ₂ at the upward displacement distance Δh ₂ are expressed by the above equations (5) to (5) It calculated | required using (8).
Upward displacement distance Δh ₂ = 1 / (2 × 9.8) = 0.051 m
Angular velocity ω = √ (9.8 / 10) = 0.990 rad / s
Period T = 2π / 0.990 = 6.34 s
Winding speed Vvm ₂ = 8 × 0.051 / 6.34 = 0.064 m / s
[0042]
As described above, when the crane 1 is stopped, linear deceleration is performed in accordance with the time of the quarter period of the pendulum, and at the same time, the suspended load 5 is moved by the upward displacement distance Δh ₂ within the time of the quarter period of the pendulum. By winding up, the gravitational spring of the pendulum generated by the deceleration cancels out and the suspended load 5 does not swing, so that the suspended load 5 stops accurately at the stop point.
[0043]
Next, an example of a simple embodiment of the suspension load control method of the present invention will be described with reference to FIG.
[0044]
The crane traveling speed is set in advance, and when the crane is accelerated, linear acceleration (constant change) is performed so that the crane at the traveling start point (speed V ₀ = 0) reaches the maximum traveling speed V ₁ after t time. Rate acceleration). Further, when the crane traveling at the set traveling speed V ₁ is stopped, linear deceleration (deceleration at a constant rate of change) is performed from the time point t before the stopping point in order to stop at the scheduled stopping point. The linear acceleration and linear deceleration operations are completed in a period of a quarter cycle of the suspended load swing cycle T = π / 2ω.
[0045]
As described above, the swing of the suspended load can be reduced by simple control in which the operations of the linear acceleration and the linear deceleration are completed within the time of a quarter cycle of the suspended load.
[0046]
It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.
[0047]
【The invention's effect】
According to the present invention, during the acceleration of the crane, the linear acceleration time of the crane is made to coincide with the time of the quarter period of the pendulum, and at the same time as the acceleration starts , the crane is suspended by the downward displacement distance within the time of the quarter period of the pendulum. The gravity spring of the suspended load is canceled by lowering the crane. On the other hand, when the crane is stopped, the linear deceleration time of the crane is made to coincide with the 1/4 period of the pendulum and the 1/4 period of the pendulum simultaneously with the start of deceleration. The gravity spring of the suspended load is offset by hoisting the suspended load by the upward displacement distance within this time, so that the suspended load can be prevented from shaking when the crane is accelerated and stopped. Therefore, effective suspension of suspended loads can be achieved with a simple apparatus configuration by feedforward control.
[Brief description of the drawings]
FIG. 1A is a diagram illustrating a speed control method during acceleration of a crane according to the present invention, and FIG. 1B is a diagram illustrating a principle of steadying a suspended load during acceleration of the crane.
2A is a diagram showing a speed control method when a crane is stopped according to the present invention, and FIG. 2B is a diagram showing a principle of steadying a suspended load when the crane is stopped.
FIG. 3 is a block diagram of a control apparatus for carrying out the present invention.
FIG. 4 is a flowchart for performing suspension control of a suspended load during acceleration of the crane according to the present invention.
FIG. 5 is a flowchart for performing steadying control of a suspended load when the crane is stopped according to the present invention.
FIG. 6 is a diagram showing a simple form example of the hanging load steadying control method of the present invention.
FIG. 7 is an explanatory view showing the principle of occurrence of a swing of a suspended load.
[Explanation of symbols]
1 Crane 5 Hanging load V ₁ Travel speed Δh ₁ Downward displacement distance Δh ₂ Upward displacement distance F ₀ Dead point R ₀ Dead point R ₁ Bottom point T Period

Claims (1)

When accelerating the crane, linear acceleration is performed from the travel start point to the set travel speed, the downward displacement distance when the pendulum with the travel start point as the dead point moves to the lowest point, and a quarter cycle of the pendulum And calculating in advance ,
On the other hand, when the traveling crane stops, linear deceleration is performed from the deceleration start point of the traveling speed to the stop point, and the upward displacement distance when the pendulum with the deceleration start point as the lowest point moves to the dead point, Calculate the 1/4 period of the pendulum in advance ,
When accelerating the crane, the linear acceleration time of the crane is made to coincide with the time of a quarter cycle of the pendulum, and simultaneously with the start of acceleration, the suspended load is unwound by the downward displacement distance within the time of a quarter cycle of the pendulum ,
On the other hand, when the crane is stopped, the linear deceleration time of the crane is made to coincide with the 1/4 period of the pendulum, and the suspended load is wound up by the upward displacement distance within the 1/4 period of the pendulum simultaneously with the start of the deceleration. A suspension control method for a suspended load.

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