JPH09267989A - Control method for preventing oscillation of hoisted load of crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately stop the oscillation of a crane, even a crane, which performs the hoisting up/down work at a high speed and of which driving system has the spring characteristic, by setting angle and velocity of oscillation of a hoisted load at zero at the time of conclusion of a speed reduction block as one of speed patterns of the traveling control of a crane. SOLUTION: A trolley position detecting device 11 for detecting position of a trolley 1, which travels on a rail 2, from a starting point detects the traveling position of the trolley 1 on the basis of the rotated variable of wheels of the trolley 1, and a lope length detecting device 12 for detecting length of a rope 4 at the time of traveling detects the length of the rope 4 on the basis of the number of revolution of a hoisting/lowering motor 17. A speed pattern generating device 13 generates the speed pattern to be given to the trolley 1 on the basis of the preset acceleration pattern, and a traveling control device 15 is formed of a minor control loop for realizing the operation speed command to be given from an external equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling steady rest of a crane load in a rope suspension crane.

[0002]

2. Description of the Related Art Generally, in crane operation, it is desired to shorten the so-called cycle time for hoisting a load, traveling laterally, and unloading the load to improve the cargo handling efficiency as much as possible. At this time, if the residual vibration of the load occurs at the end of the lateral traveling, it is not possible to unload the suspended load for safety. Therefore, it is necessary to wait until the vibration of the load falls within the allowable range.
This increases cycle time and causes a decrease in cargo handling efficiency. Particularly in manned cranes, steady rest control is performed based on the driver's intuition and experience, and it took a considerable amount of time to become skilled.

On the other hand, there are two types of steady rest control mechanisms for unmanned cranes, a mechanical control mechanism and an electrical control mechanism. In the former mechanical control mechanism, the movable part such as the crane hook is structurally fixed, so in principle, no shake occurs and complete steady control is possible. However, in the case where the existing equipment is modified, for example, the latter electric control mechanism is often more advantageous in terms of cost. Further, the mechanical control mechanism needs to wind the suspended load to the maximum position before traveling, which is disadvantageous in terms of cycle time. From this point of view, the need for a crane equipped with an electric steady rest mechanism is increasing.

Conventionally, in a crane operation control method provided with an electric steady rest control mechanism, an acceleration / deceleration time related to a swing cycle of a suspended load is set based on a model in which the crane-suspended load system is regarded as a single pendulum, and In many cases, speed pattern control that does not leave runout is adopted as a rule. The speed pattern control methods currently known are roughly classified into FIG. 10 (a).
As shown in Fig. 10, a method of combining a plurality of time sections in which the crane acceleration during operation is constant and controlling the crane speed pattern to be a broken line as shown in Fig. 10B (Japanese Patent Publication No. 61-031032). And FIG.
A method in which the crane acceleration is continuously changed as shown in (a) and the crane speed pattern is controlled so as to draw a smooth continuous curve as shown in FIG. 11 (b) (JP-A-6-3).
05686). And, in the latter publication, it is described that by making the acceleration change continuous, it is difficult to induce rattling of the reduction gear and twist of the drive shaft, and it is possible to realize steady rest.

All of the above are those in which the crane-hoisting system is regarded as a single pendulum, but in the case of a crane whose cycle time is stricter, there are cases where the rope for hoisting the hoisted load is hoisted and unwound simultaneously and traveling. is there. In such a case, if an attempt is made to generate a steady-state pattern while considering a swing cycle corresponding to a continuously changing rope length, it becomes much more complicated than when the rope length is fixed. This is because the solution of the equation of motion for a suspended load that takes into account changes in rope length cannot be represented by an elementary function. Then, an operation control method based on this equation of motion was devised strictly, but the number of calculations was very large, which imposes a great restriction on the control device, which is not practical.

Therefore, a simple operation control method based on the simple pendulum model when the rope length is fixed is disclosed in Japanese Patent Application Laid-Open No. 5-270786 as a method which can be applied to simultaneous operation of hoisting / lowering and traveling. There is a method for controlling the steady of the suspended load. The steady load control method of the suspended load disclosed in the same publication obtains the swing cycle of the suspended load by regarding the average value of the rope lengths for hoisting and unwinding the suspended rope as a representative value of the rope length that changes with time, and The speed pattern control is used to stop the shake.

[0007]

However, the steady rest control method disclosed in the above-mentioned publication is intended for an overhead crane having a small hoisting / lowering speed range (8 m / min), and discontinuous acceleration changes. It is based on the speed pattern that it has. Therefore, it cannot be applied to a container crane that has a large speed range of hoisting and hoisting, such as a container crane that hoists and unloads containers on the quay. Therefore, the speed of hoisting / lowering is 70m / min ~ 150m / m
As a method for performing the steady rest control in a container crane having some in, it is conceivable to perform speed control of the crane based on an acceleration pattern in which the acceleration changes discontinuously as shown in FIG. 12, for example. The acceleration pattern shown in FIG. 12 is a steady rest acceleration pattern when traveling while hoisting a suspended load, and the acceleration is switched from η ₃ to η ₄ after half the total acceleration time has elapsed.

As described above, theoretically, the steady rest can be realized even with the acceleration pattern in which the acceleration is discontinuously changed. However, in reality, when the acceleration is changed discontinuously, it causes adverse effects such as slipping of the crane and rattling of the reducer, and it is not possible to achieve steady rest accurately and it also leads to machine failure. there is a possibility.

Many container cranes are not of the self-propelled type, for example, of the type in which a trolley 57 is pulled by a wire rope 55 stretched from a motor 53 installed in an electric room 50 as shown in FIG. Moreover, in this method, the total length of the wire rope 55 reaches 200 m, which is equivalent to the existence of a spring between the motor 53 and the trolley 57. For such a container crane,
According to the acceleration pattern shown in FIG.
When the anti-rest control is performed by traveling 7, the abrupt change in the acceleration of the trolley 57 affects the wire rope 55 that pulls the trolley (influence of the spring). Can't get

The present invention has been made in view of such circumstances, and it is possible to achieve a highly accurate steady rest even for a crane having a high hoisting / lowering speed and a drive system having a spring characteristic or the like. It is an object of the present invention to provide a steady rest control method for a crane suspended load.

[0011]

SUMMARY OF THE INVENTION A steadying control method for a crane suspended load according to the present invention is achieved by performing traveling control of a suspended crane that travels while hoisting or unwinding a suspended load based on a speed pattern. In the thing for steadying the suspended load, the speed pattern is decelerated from the acceleration section for accelerating the crane to a predetermined speed, a constant speed section for maintaining the predetermined speed accelerated in the acceleration section, and the predetermined speed. A deceleration section for stopping the crane, linearly increasing or decreasing the acceleration pattern in the acceleration section or deceleration section from zero value to a predetermined acceleration η ₁ over time T ₁ , and time T ₂ During that time, the step B of maintaining the acceleration η ₁ and the step C of linearly changing from the acceleration η ₁ to a predetermined acceleration η ₂ over time T ₃ and the time T ₄ includes a step D of maintaining the acceleration η ₂ during ₄ and a step E of linearly decreasing or increasing the acceleration η ₂ to a zero value over time T ₅ , and the steps T ₁ , T ₂ , T The relationship among ₃ , T ₄ , T ₅ , η ₁ and η ₂ is set so that the swing angle of the suspended load and the swing angular velocity of the suspended load become zero at the end of the process E.

Further, it is characterized in that the time T ₂ and the time T ₄ are zero values, and there is no interval for holding the acceleration at a constant value.

Further, the time T ₁ is equal to the time T ₅ .

Further, the initial rope length at the start of acceleration or deceleration or the swing cycle and winding speed associated with the initial rope length and the suspended load are divided into appropriate sections.
In the dimension parameter table, the T ₃ and the acceleration η
₁ and η ₂ , or the T ₃ and the accelerations η ₁ and η
5. The steady rest control of a crane suspended load according to claim 4, wherein a ratio of ₂ is stored and a steady rest parameter suitable for the operating condition is derived by interpolation calculation from the two-dimensional parameter table before the crane operation. Method.

Further, the steady rest pattern generating portion and the steady rest parameter calculating portion are registered as separate tasks in a computer equipped with a multitasking operating system, and the steady rest pattern generating portion calculates the steady rest pattern of the work. In parallel with the above, the steady rest parameter calculation unit calculates the steady rest parameter of the next work from the next work operation condition consisting of the rope length at the start of acceleration or deceleration or the runout period and the winding speed. 4. A method for controlling the steady rest of a crane suspended load according to 4.

[0016]

1 is a block diagram showing an automatic crane control device to which a crane operation control method according to an embodiment of the present invention is applied. In the figure, reference numeral 1 denotes a trolley, which travels in the x direction on a rail 2 while a hoisting load 3 attached to a lower end of a rope 4 is being hoisted and unwound. The trolley position detecting device 11 and the rope length detecting device 12 control the traveling of the trolley 1.
A speed pattern generation device 13, a traveling motor control device 14, a traveling speed control motor 15, a hoisting / lowering speed control device 16, and a hoisting / lowering speed control motor 17.

The trolley position detecting device 11 is a device for detecting the position of the trolley 1 traveling on the rail 2 from the starting point, and detects the traveling position of the trolley 1 from the rotation amount of the wheels of the trolley 1. You can do it. The rope length detection device 12 is a device for detecting the length of the rope 4 during traveling, and is adapted to detect the length of the rope 4 from the number of rotations of the hoisting / lowering motor 19 for the rope 4. There is. The speed pattern generation device 13 is a device that generates a speed pattern to be given to the trolley 1 according to a previously given acceleration pattern. Travel motor controller 15
Is composed of a minor control loop for realizing an operating speed command given to the traveling speed control motor 15 from the outside.

The crane operation control method according to the following embodiments of the present invention is realized by such an automatic control device. In the present embodiment, as shown in FIG.
The mass of the suspended load 3 is m, the deflection angle of the suspended load 3 is θ, and the trolley 1
Is set to x, and the trolley 1 accelerates on the rail 2 on the acceleration d ² x
It is assumed that the vehicle runs at / dt ² (hereinafter referred to as α) and the length L of the rope length 4 changes with time. Assuming that the swing of the suspended load 3 is not large, description will be given using the equation of motion of the swing angle θ seen from the trolley 1 represented by the following equation (1).

[0019]

[Equation 1]

Here, it is assumed that the rope length L changes as L = a + bt (where a: initial rope length, b: hoisting / lowering speed). At this time, (1)
The solution of the equation is expressed using the Bessel function, and its analytic property becomes complicated. In particular, the higher the hoisting / lowering speed is, the more difficult it is to analytically derive the steady-state speed pattern. Therefore, in the following, a steady rest acceleration pattern is derived by a computer using an optimization method so that both the swing load swing angle θ and the swing angular velocity dθ / dt become zero at the end of acceleration (or deceleration) of the trolley 1. .

FIG. 3 shows the most general acceleration pattern of the present invention when the trolley 1 travels while hoisting a suspended load. The acceleration pattern shown in FIG. 3 shows the time change of the acceleration in the acceleration section, and the acceleration is changed from the zero value to the predetermined acceleration η over the time T _1.
A step A for linearly increases to _1, the linear step B of holding the acceleration during the time T ₂ in the acceleration eta _1, the acceleration from the acceleration eta ₁ over time T ₃ to a predetermined acceleration eta ₂ From step C of increasing the acceleration to η ₂ during the time T ₄ , and step E of linearly decreasing the acceleration from the acceleration η ₂ to zero over the time T _5. It consists of In this acceleration pattern, the specific values of the times T ₁ , T ₂ , T ₃ , T ₄ , T ₅ , and the acceleration ratio η ₂ / η ₁ should be derived by the computer using the optimization method as described above. To do.

Next, the initial rope length is 25 m and the winding speed is -1.
The effect of the present embodiment will be described by taking as an example the case where the vehicle travels while being wound up at m / s and a maximum trolley acceleration of 0.5 m / s ² . Further, for simplification of explanation, acceleration rise time T ₁ = acceleration fall time T ₅ = 3.0 sec and acceleration hold time T ₂ = T ₄ = 0.0 are set. The acceleration pattern under this condition is as shown in FIG.
The steady rest parameters are T ₃ and the acceleration ratio η ₂ / η ₁ .

In the container crane shown in FIG. 13, assuming that there is no spring characteristic between the motor and the trolley, the parameters are calculated by the computer using the optimization method so as to realize the steady rest at the end of acceleration. It is calculated that ₃ = 5.816 sec η ₂ / η ₁ = 1.348. As a comparative example, when the total acceleration time and the acceleration ratio η ₄ / η ₃ which are parameters for the acceleration pattern shown in FIG. 12 are calculated, the total acceleration time = 9.089 η ₄ / η ₃ = 1.184 is calculated. .

Next, consider a model having spring characteristics between the motor and the trolley in the container crane shown in FIG. In addition, this model is assumed to be equipped with a damper to damp the vibration due to the spring. First,
When the position command value of the trolley calculated from the speed instruction value of the motor is Xref and the actual position of the trolley is X, the equation of motion of the trolley is as shown in the following equation (2).

[0025]

[Equation 2]

By applying the acceleration pattern of this embodiment shown in FIG. 4 and the acceleration pattern of FIG. 12 to the above equation of motion, changes in the speed of the trolley and changes in the swing angle of the suspended load are simulated. In the following simulation,
ζ / m was 0.15 / s and K / m was 10.0 / s ² . 5 and 6 show simulation results, FIG. 5 is based on the acceleration pattern of the present embodiment, and FIG. 6 is an application of the acceleration pattern of FIG. 5 (a) and 6 (a) show changes in the speed of the trolley. In the figure, the dotted line represents the speed command value given to the motor, and the solid line represents the speed of the trolley. Also, FIG.
FIG. 6B and FIG. 6B show changes in the deflection angle of the suspended load.

As can be seen from FIGS. 5 (a) and 6 (a), the trolley speed oscillates due to the influence of the spring characteristics in both the present embodiment and FIG. 12, but the amplitude is the present embodiment. It is smaller when the acceleration pattern of is applied. Therefore, as shown in FIGS. 5B and 6B, the steady rest error at the end of acceleration is ± 0.2 degrees in the conventional method, while it is ± 0.08 degrees in the present invention. And is greatly reduced. From the above simulation, it was confirmed that according to the acceleration pattern of the present embodiment, the steady rest can be accurately realized even for the type of crane in which the trolley is towed by the wire rope as shown in FIG.

When applying the steady rest control method of the present invention to an actual crane, the points to be noted are that the operating conditions (initial rope length, hoisting speed) differ for each crane operation, and the steady rest is set for each of these different operating conditions. The parameters are also different. Therefore, two methods will be presented below as methods for obtaining the steady rest parameter for each operating condition.

The first method is a pre-processing device for the steady-state pattern generating device 13 shown in FIG. 1, and a steady-state parameter for interpolating an appropriate steady-state parameter from the steady-state parameter table according to an operating condition. It is to put a computing device. FIG. 7 is an explanatory diagram for explaining the first method. The first method will be described with reference to FIG. Prepare a steady rest table that covers all possible operating conditions, calculate steady rest parameters offline for each operating condition, and assign them to the steady rest table. In the steady rest parameter table, the vertical axis represents the initial rope length and the horizontal axis represents the winding speed. Theoretically, there is a one-to-one relationship between the rope length (measurement rope length) and the runout cycle, but in reality the length up to the center of gravity changes depending on the weight of the suspended load, so the runout cycle is different even if the measurement rope length is the same. There are cases. Therefore, it is appropriate to adopt the rope length (rope length to the center of gravity) calculated back from the actual swing cycle as the vertical axis. It is also possible to use the deflection cycle itself as the vertical axis, instead of the rope length. The runout cycle at this time is derived by storing the runout cycle measured in a two-dimensional table consisting of the measured rope length and the suspension load amount and performing linear interpolation.

In this example, the initial rope length is 5 to 25 m
Winding speed is from 2.5m to 5m, winding speed is from -1.0m / s to 1.0m / s
Up to 0.5 m / s is tabulated, and steady rest parameters (for example: T ₃ , η ₂ / η ₁ ) at each point are stored. Then, the steady rest parameters to be used are calculated by linearly interpolating this table for the actual operating conditions. Generally, the steady rest parameter (T
₃ , η ₂ / η ₁ ) does not have a linear relationship between the initial rope length and the winding speed, and therefore an error is generated by the linear interpolation calculation. As a method to reduce this error as much as possible,
It is possible to make the table mesh finer,
There is a problem that the labor of offline calculation increases. Therefore, this method can be adopted when the operating conditions are relatively limited and the vertical and horizontal range of the table is narrow, or when the steady rest is not so highly required. In the above example, T ₃ and acceleration ratio η ₂ /
η ₁ is shown, but instead of this, T ₃ and accelerations η ₁ , η
₂ or T ₃ and the acceleration ratio η ₁ / η ₂ may be substituted.

The second method is to derive a highly accurate steady rest parameter without error due to linear interpolation without using the steady rest parameter table. FIG. 8 is an explanatory diagram illustrating the second method. As shown in FIG. 8, the steady rest pattern generating unit and the steady rest parameter calculating unit are registered as separate tasks in a computer equipped with a multi-task operating system. Then, while performing the calculation of the work in the steady rest speed pattern generation unit,
Based on the shake model (1) and the operating conditions of the next work, the steady rest parameters of the next work are calculated by optimization. With the recent improvements in computer performance and advances in operating systems (OS), such a configuration has become feasible. It is a good idea to use this method when extremely steady rests are required or when the operating conditions are subject to change and the method of cutting the mesh in the parameter table cannot be uniquely determined. Also in this case, the center-of-gravity rope length is required, and the run-out period table is interpolated linearly.
In this method, since the error is accumulated because both the shake period table and the steady rest parameter table are linearly interpolated, this method is only affected by the linear interpolation error of the shake period table.

The acceleration pattern in FIG. 3 is an example of traveling while hoisting a load in the acceleration traveling section of the crane. In the deceleration traveling section of the crane, the absolute values of η ₁ and η ₂ are the same. Then, the sign may be reversed. Also, when traveling while hoisting a suspended load,
As shown in FIG. 9, in step C, the acceleration may be linearly reduced from the acceleration η ₁ to a predetermined acceleration η ₂ over time T ₃ . However, the acceleration pattern shown in FIG. 9 is not limited to traveling while hoisting a hoisted load, and even when traveling while hoisting a hoisted load, for example, the hoisting speed of the hoisted load is slow and the effect of hoisting. When the influence of natural damping is larger than that, the acceleration pattern as shown in FIG. 9 may be obtained.

Further, by combining the speed pattern control according to the present invention and the feedback control using the deflection angle sensor signal, a control system which is strong against disturbance and modeling error can be constructed.

[0034]

As described above, in the present invention,
Since the acceleration pattern that controls the traveling of a suspended crane that travels while hoisting or hoisting a suspended load is continuously changed, the hoisting and lowering speed is high, and the drive system has spring characteristics etc. High-precision steady rests can also be achieved for cranes.

[Brief description of drawings]

FIG. 1 is a block diagram showing an automatic control device for a crane applied to one embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating operations of a crane and a suspended load applied to one embodiment of the present invention.

FIG. 3 is a graph showing an acceleration pattern that is an embodiment of the present invention.

FIG. 4 is a graph showing an acceleration pattern according to another embodiment of the present invention.

FIG. 5 is a diagram showing a simulation example in which the present embodiment is applied to a crane model having a spring characteristic between a motor and a trolley.

FIG. 6 is a diagram showing a simulation example in which an acceleration pattern in which acceleration changes discontinuously is applied to a crane model having a spring characteristic between a motor and a trolley.

FIG. 7 is an explanatory diagram illustrating a first method of deriving a steady rest parameter.

FIG. 8 is an explanatory diagram illustrating a second method for deriving a steady rest parameter.

FIG. 9 is a graph showing an acceleration pattern according to another embodiment of the present invention.

FIG. 10 is a diagram showing an example of a known steady rest pattern.

FIG. 11 is a diagram showing another example of a known steady rest pattern.

FIG. 12 is a graph showing an acceleration pattern in which the acceleration changes discontinuously.

FIG. 13 is a schematic diagram of a drive system of a container crane.

[Explanation of symbols]

 1 Trolley 2 Rail 3 Lifting load 4 Rope

Claims (6)

[Claims] 1. A steadying control method for a crane suspended load for steadying the suspended load by performing traveling control of a suspension crane that travels while hoisting or unwinding a suspended load based on a predetermined speed pattern. In the above, the speed pattern includes an acceleration section for accelerating the crane to a predetermined speed, a constant speed section for maintaining the predetermined speed accelerated in the acceleration section, and a deceleration section for decelerating from the predetermined speed and stopping the crane. , Step A of linearly increasing or decreasing the acceleration pattern in the acceleration section or the deceleration section from zero value to a predetermined acceleration η ₁ over time T ₁ , and holding the acceleration η ₁ for time T _2. and step B, the step C be linearly varied from the acceleration eta ₁ over time T ₃ to a predetermined acceleration eta _2, to hold the acceleration eta ₂ during time T ₄ And step D, were composed of a step E for linearly decreasing or increasing to zero value from the acceleration eta ₂ over time T _5, the _{T 1, T 2, T 3} , T 4, T 5, η 1 , Η ₂ is set so that the swing angle of the suspended load and the swing angular velocity of the suspended load become zero at the end of the process E. 2. The steady rest control method for a crane suspended load according to claim 1, wherein the time T ₂ and the time T ₄ are set to zero and there is no section for holding the acceleration at a constant value. 3. The steady rest control method for a crane suspended load according to claim ₁ , wherein the time T ₁ is equal to the time T ₅ . 4. The steady rest control method for a crane suspended load according to claim 2, wherein the time T ₁ is equal to the time T ₅ . 5. The two-dimensional parameter table configured by dividing the initial rope length at the start of acceleration or deceleration or the initial rope length and the swing cycle and winding speed associated with the suspended load into appropriate sections, the T ₃ and The accelerations η ₁ and η ₂ or the ratio of T ₃ and the accelerations η ₁ and η ₂ are stored, and steady rest parameters suitable for the operating conditions are interpolated from the two-dimensional parameter table before the crane operation. The steady rest control method for a crane suspended load according to claim 4, which is derived. 6. A steady-state pattern generating section and a steady-state parameter calculating section are registered as separate tasks in a computer equipped with a multi-task operating system, and the steady-state pattern generating section calculates a steady-state pattern for the work. In parallel with the above, the steady rest parameter calculation unit calculates the steady rest parameter of the next work from the next work operation condition consisting of the rope length at the start of acceleration or deceleration or the runout period and the winding speed. 4. A method for controlling the steady rest of a crane suspended load according to 4.