Anti-sway control method for a rotary crane

Abstract

To provide a swing stop control method of a revolving crane capable of shortening a conveyance time of a suspended cargo by eliminating residual swing during the stope of the crane in the swing stop control of the revolving crane.SOLUTION: A swing stop control method of a revolving crane 1 performs feedforward control for stopping the swing of a suspended cargo 5 after arriving at an end point when the suspended cargo 5 is conveyed from a start point to the end point by using the revolving crane 1 having a boom 11. The residual swing amount is estimated by using a temporary acceleration pattern or a temporary speed pattern for conveying the suspended cargo 5 from the start point to the end point. A compensation pattern for cancelling the estimated residual swing amount is calculated. After arriving at the end point, the compensation pattern is applied to the temporary acceleration pattern or the temporary speed pattern by going back the time that is the integral multiple of a swing period of the suspended cargo so as to calculate the acceleration pattern or the speed pattern for conveying the suspended cargo 5. The suspended cargo 5 is conveyed by using the calculated acceleration pattern or the temporary acceleration pattern.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an anti-sway control method for a rotary crane. [Background technology]

[0002] In the transport operation of a crane, when a suspended load is transported from a start point to an end point, a method of performing anti-sway control is used so that the suspended load does not sway after arriving at the end point.

[0003] For example, Non-Patent Document 1 and Patent Document 1 disclose a method for controlling sway in an overhead crane, in which an acceleration pattern or speed pattern of the crane transport is used to prevent the sway of the suspended load at the stopping position (end point) after transport.

[0004] Furthermore, Patent Document 2 discloses anti-sway control for a rotary crane, which includes a swinging motion, unlike the linear traveling and traversing transport of overhead cranes. However, the method disclosed in Patent Document 2 cannot completely prevent the swing of the suspended load, so feedback control using an optimal regulator is performed. Furthermore, Non-Patent Document 2 discloses a method for anti-sway control for a rotary crane, which adds an expert's control strategy to pattern generation and further adds feedback control. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-30776 [Patent Document 2] Japanese Patent Application Publication No. 64-64996 [Non-patent literature]

[0006] [Non-Patent Document 1] Automation of Overhead Cranes, NKK Technical Report No. 149, 40 / 45 (1995) [Non-patent document 2] Control of a Rotating Crane Considering Expert Control Strategies, SISE Proceedings Vol. 33, No. 9, 923 / 929 (1997) Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the anti-sway control methods described in Patent Document 2 and Non-Patent Document 2, the load sways (residual sway) after the crane stops, and this is suppressed by feedback control, which has the problem of taking a long time to achieve anti-sway.

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a control method for anti-sway control of a rotary crane that can shorten the transport time of a suspended load by eliminating residual sway when the crane is stopped. [Means for solving the problem]

[0009] According to one aspect of the present invention, when a suspended load is transported from a start point to an end point using a rotary crane with a boom, a sway control method is provided that performs feedforward control to prevent the sway of the suspended load after the load arrives at the end point. The method estimates the residual sway using a provisional acceleration pattern or provisional velocity pattern for transporting the suspended load, and calculates a compensation pattern that cancels out the estimated residual sway. This compensation pattern is applied to the provisional acceleration pattern or provisional velocity pattern for a time period that is an integer multiple of the sway period, counting back from the end time of transport. The applied pattern is used for transport, and sway prevention is performed at the stop position. [Effects of the Invention]

[0010] According to one aspect of the present invention, in anti-sway control of a rotary crane, residual sway when the crane is stopped can be eliminated, thereby shortening the transport time of a suspended load. [Brief explanation of the drawings]

[0011] [Figure 1] Anti-sway control method for a rotary crane [Figure 2] Rotation (θ-axis) acceleration pattern used to estimate residual shake [Figure 3] Pull-in (r-axis) acceleration pattern used for residual shake estimation [Figure 4] Boom tip position route during transport [Figure 5] Radar chart of the amount of vibration during and after a turn [Figure 6] Changes in residual runout in the X-axis and Y-axis directions [Figure 7] Impulse response of deflection angle, (A) input square wave, (B) deflection angle transition caused by square wave [Figure 8] Example of generating a vibration prevention pattern (compensation pattern), (A) Transition of the residual vibration angle, (B) Timing and amount of compensation for the residual vibration [Figure 9] Results of residual steadying using compensation patterns: (A) acceleration of the swing angle, (B) velocity of the swing angle, (C) swing angle [Figure 10] Example of moving the start time of the compensation pattern back by twice the swing period [Figure 11] Corrected rotation (θ axis) acceleration pattern [Figure 12] Corrected retraction (r-axis) acceleration pattern [Figure 13] Amount of vibration during and after turning due to the corrected acceleration pattern [Figure 14] Block diagram for determining the manipulated variable for feedback control of the swing angular velocity [Figure 15] Compensation amount pattern on the X axis [Figure 16] Compensation amount pattern on the Y axis [Figure 17] Corrected rotation (θ axis) acceleration pattern [Figure 18] Corrected retraction (r-axis) acceleration pattern [Figure 19] Amount of vibration during and after turning due to the corrected acceleration pattern DETAILED DESCRIPTION OF THE INVENTION

[0012] In the following detailed description, embodiments of the present invention will be described with reference to the drawings. Each drawing is a schematic diagram and may differ from the actual product. The embodiments shown below exemplify devices and methods for embodying the technical concept of the present invention. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0013] <Embodiment 1> An anti-sway control method according to a first embodiment of the present invention is shown in Figure 1. A slewing crane 1 has a boom 11 and transports a load 5 suspended from the tip of the boom 11 from a start point to an end point by performing slewing and retracting operations. One such slewing crane is a horizontal retractable crane (LLC), and the following discussion will be based on this assumption. Note that the tip position of the boom 11 of the slewing crane 1 is expressed in polar coordinates for the slewing and retracting operations, and the sway angle is expressed in Cartesian coordinates. For this reason, coordinate conversion between these two is performed.

[0014] The slewing crane 1 is equipped with a slewing control device 2, a retraction control device 3, and an anti-sway control device 4. The slewing control device 2 detects the slewing angle of the boom 11 of the slewing crane 1, and outputs a speed command to a motor that performs a slewing operation in accordance with an acceleration pattern or a speed pattern generated by the anti-sway control device 4 in accordance with the movement conditions. In addition, the retraction control device 3 detects the tip position of the boom 11 of the slewing crane 1, and outputs a speed command to a motor that performs a retraction operation in accordance with an acceleration pattern or a speed pattern generated by the anti-sway control device 4 in accordance with the movement conditions.

[0015] The anti-sway control device 4 is a device that generates an acceleration pattern or a speed pattern that takes into consideration a compensation pattern that cancels out the amount of residual sway in accordance with the residual sway estimated from the movement conditions of the suspended load 5, using a method that will be described later.

[0016] Here, we will explain the residual sway in the rotary crane 1. Under the transport conditions shown in Table 1, the rotation (θ-axis) acceleration pattern and retraction (r-axis) acceleration pattern of the rotary crane 1 generated using the method described in Patent Document 1 as anti-sway control are shown in Figures 2 and 3.

[0017] [Table 1]

[0018] The path of the tip position of the boom 11 at this time is shown in Figure 4. The radar chart in Figure 5 shows the amount of sway of the suspended load 5 during rotation (during transport from start point A to end point B in Figure 4) and the amount of residual sway of the suspended load 5 after rotation (after arrival at end point B). With an acceleration pattern that transports the suspended load 5 in a straight line, as in Patent Document 1, an elliptical residual sway occurs, indicating that the load is not properly sway-controlled.

[0019] The anti-sway control device 4 of the crane 1 will now be described. First, a tentative acceleration pattern is generated according to the movement conditions, but a known acceleration pattern such as those shown in Figures 2 and 3 may be used. Next, this tentative acceleration pattern is used to estimate the amount of residual sway. Figure 6 shows a trend display starting from the start of the residual sway (end of transport).

[0020] Next, the operation amount and operation timing that cancel out the estimated residual shake, i.e., the compensation pattern, is calculated. This compensation pattern is made up of multiple patterns of the same shape, but in the following explanation, this pattern of the same shape is assumed to be a square wave. The relationship between the acceleration applied to the suspended load to cancel out the residual shake, the acceleration of the suspended load, and the sway angle of the suspended load (amount of residual shake) is shown in equations (1) and (2).

[0021]

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[0022] The impulse response of the crane acceleration on the X-axis and Y-axis shown in equations (1) and (2) is calculated. As shown in Figure 7(A), the X-axis acceleration is 0.1 m / sec 2 Figure 7(B) shows the transition of the sway angle that occurs when 10 samples of a square wave are input, for a total of 1. The rope length L at this time is 10 m. From this impulse response, the operating amount that cancels out the residual sway can be determined. In this example, the area (height x 2) of the positive side of the sine wave (0 to π) is 0.01, so the gain is 0.01. Note that this gain may be calculated according to the rope length L based on equations (1) and (2), or may be set in advance as a table.

[0023] In residual sway prevention, the sway prevention is performed by moving the slewing crane 1, so the stopping position of the slewing crane 1 must not change when the slewing crane 1 is moved. In other words, the sum of the movement distances of the tip of the boom 11 must be 0 m. Also, the sum of the speeds (time integral) of the tip of the boom 11 for sway prevention must be 0 m / sec, and the sum of the accelerations (time integral) of the tip of the boom 11 must be 0 m / sec. 2 An example of a compensation pattern that satisfies these conditions is shown in Figure 8.

[0024] FIG. 8(A) shows the shake angle X, which is the residual shake amount in the X-axis direction shown in FIG. 6, and FIG. 8(B) shows the compensation pattern. In this example, it is composed of a total of three square waves, two on the positive side and one on the negative side, each with a width of 10 samples. 1、 t 2、 t3 is the time when the deflection angle is inverted, and the start times of each square wave are based on these times, t1, t2, t3, before the 10 sampling.

[0025] Note that the compensation pattern shown in Figure 8(B) is the result of fine-tuning the start times because the square waves have widths, and different fine-tuning can also be performed. For example, the start times of each square wave can be set to t1, before t25 sampling, and before t310 sampling.

[0026] Due to the constraints of pattern generation described above, the manipulated variable (square wave height) must satisfy equations (3) to (5). Here, U in equations (3) to (5) is calculated using equation (6). Also, the 2 in the numerator of equation (6) is used to calculate the area, and the 2 in the denominator is used to represent one side of the operation, since it is performed in both directions.

[0027]

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[0028] The results of vibration suppression in the X-axis direction using the compensation pattern in Figure 8(B) are shown in Figure 9. Figure 9(A) shows the vibration angular acceleration, Figure 9(B) shows the vibration angular velocity, and Figure 9(C) shows the time change in the vibration angle after reaching the end point. By applying the compensation pattern, it can be seen that the vibration angular velocity and vibration angle gradually attenuate, enabling vibration suppression.

[0029] To prevent the sway of the suspended load 5 at the end of transport, the compensation pattern is moved toward the transport side by an integer multiple of the sway period and applied to the temporary acceleration pattern, provided that there is almost no damping in the sway of the suspended load 5 and that the rope length L does not change. Figure 10 shows an example of moving the compensation pattern shown in Figure 8(B) back in time from the arrival time at the end point by a time twice the sway period. By generating such a compensation pattern, it is possible to prevent the sway when the load arrives at the end point (at the end of transport), thereby shortening the transport time. In addition, feedback control to attenuate the residual sway is not required.

[0030] In the present invention, after estimating the residual shake amount, this residual shake amount is evaluated, and only when the residual shake is large, a compensation pattern is calculated, and an acceleration pattern or speed pattern is calculated as in the above embodiment, and the suspended load 5 is transported. On the other hand, when this residual shake amount is small, the tentative acceleration pattern or tentative speed pattern is used as the acceleration pattern or speed pattern, and the suspended load 5 is transported. By performing this evaluation verification before constructing the execution system, there is a possibility that this calculation process can be simplified. Note that the threshold value for this evaluation is preferably 0.01 rad.

[0031] [Example 1] The simulation method for preventing sway of a rotary crane in the first embodiment and the results thereof are shown as Example 1. (Perfect anti-vibration pattern generation) The acceleration patterns shown in Figures 2 and 3 are assumed to be provisional patterns, and the residual shake amount for this pattern is calculated. Here, to express the residual shake amount in Cartesian coordinates, the acceleration patterns for rotation (θ axis) and retraction (r axis) are converted to Cartesian coordinates (X axis, Y axis) according to equations (7) and (8). Note that there are also parameters related to speed and position in addition to acceleration, but these can be calculated by integrating and doubling the acceleration. Also, the first term on the right-hand side of equation (7) is the X-axis acceleration component due to retraction, the second term is the same component due to rotation, the third term is the same component due to centrifugal force, and the fourth term is the same component due to Coriolis force. Equation (8) is for the Y axis, but is similar to the X axis.

[0032]

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[0033] The residual runout of the X-axis that we want to find is θ in equation (1). X Therefore, it can be found by substituting equation (7) into equation (1) and sequentially integrating twice from the start point (start) of the transfer. Note that it is assumed that there is no vibration at the start point of the transfer. Similarly, the vibration in the Y-axis direction can be found by substituting equation (8) into equation (2) and integrating twice.

[0034] Specifically, the simulation process involves sequentially calculating the acceleration, speed, and position in the X-axis and Y-axis directions from the rotation and retraction accelerations every 50 msec from the start of transport, and also calculating the acceleration, speed, and position of the swing angle in the X-axis and Y-axis directions accordingly.

[0035] A residual anti-sway pattern can be generated for the determined sway angle, but because this is anti-sway in a Cartesian coordinate system, the rotation (θ axis) and retraction (r axis) must be converted to a polar coordinate system. To convert from Cartesian coordinates to polar coordinate position, velocity conversion can be performed by the time derivative of the sway angle, and this second derivative can also be used to convert to acceleration. Equations (9) and (10) show the acceleration conversion.

[0036]

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[0037] If the compensation amount found according to this formula is added to the virtual acceleration patterns in Figures 2 and 3 for a period twice the shake period, going back from the time of arrival at the end point, a perfect anti-sway acceleration pattern will be obtained that does not produce residual shake. This pattern is shown in Figures 11 and 12. Six pulse-like waveforms can be seen in the trapezoidal pattern in the latter half of the figures, which are the added compensation amounts. There are three compensations for each of the X-axis and Y-axis, and the rotation (θ-axis) and pull-in (r-axis) conversions make a total of six.

[0038] (Steady-state simulation) In an actual machine, a speed pattern is generated from the acceleration patterns shown in Figures 11 and 12 and used as a speed command for the motor, but in this simulation, we will verify the amount of residual runout when the above-mentioned compensated acceleration pattern is applied. The results of this simulation are shown in Figure 13, and it can be confirmed that there is almost no residual runout compared to the runout angle after turning in Figure 5.

[0039] <Embodiment 2> Next, a sway control method according to a second embodiment of the present invention will be described. The sway control method according to the second embodiment is performed using the rotary crane 1 shown in FIG. 1, as in the first embodiment. The sway control method according to the second embodiment differs from the first embodiment in the method of estimating a compensation pattern that cancels out the residual sway amount, but the other configurations are the same. For this reason, only the method of estimating the compensation pattern will be described below, but the configurations other than the method of estimating the compensation pattern described in the first embodiment can be similarly applied to the second embodiment.

[0040] The compensation pattern is an operation amount pattern when feedback control is performed on the sway angular velocity of the suspended load 5. This feedback control of the sway angular velocity is obtained by simulating the transportation of the suspended load 5, rather than by feedback of the sway angular velocity in actual operation.

[0041] Figure 14 shows a block diagram for calculating this manipulated variable. The time series data of the trolley acceleration in Figure 14 becomes the compensation pattern. Specifically, the manipulated variable is calculated using equations (11) to (14). Note that equations (11) to (14) are written in relation to the X-axis direction in a Cartesian coordinate system, but the same is true for the Y-axis. Note that the target value at this time is zero.

[0042]

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[0043] Equation (11) calculates the feedback compensation amount, but the minus sign is added because this velocity feedback has the same sign as the feedback. Also, dividing by the sampling time is to match the treatment of acceleration in the equation of motion in equation (12). Equation (13) is the time integral to calculate the swing angular velocity, and equation (14) is the time integral to calculate the swing angle. And at time T e The amount of feedback compensation for a time period that is an integer multiple of the vibration period is calculated in accordance with equations (11) to (14), with the vibration angle, vibration angular velocity, and vibration angular acceleration at the initial values.

[0044] The sum of the accelerations and the sum of the velocities of the calculated compensation amounts cannot be made completely zero, so the stopping position of the load 5 will shift. For this reason, when estimating the compensation pattern, the compensation amount is allowed to converge while oscillating positively and negatively over a period of time more than twice the swing period, thereby minimizing the shift in the stopping position to a level that does not pose a practical problem. The feedback gain at this time is about 0.2.

[0045] Here, the anti-sway control method for a rotary crane 1 according to the first embodiment uses a square wave as the compensation pattern, which causes pulse-like irregularities in the conveyance acceleration pattern to which the compensation pattern is applied. If these pulse-like irregularities are large, there is a possibility that the motor's acceleration constraints during conveyance will be exceeded. In such a case, the maximum acceleration of the virtual acceleration pattern calculated initially must be lowered to satisfy the constraints, resulting in reduced conveyance efficiency. On the other hand, the anti-sway control method for a rotary crane 1 according to the second embodiment uses a smooth compensation pattern, which prevents pulse-like irregularities and therefore has a high probability of satisfying the motor's acceleration constraints during conveyance, preventing a decrease in conveyance efficiency.

[0046] [Example 2] A simulation method for preventing sway of a rotary crane in the second embodiment and the results thereof will be described as Example 2.

[0047] (Perfect anti-vibration pattern generation) In the second embodiment, the residual shake amount is estimated in the same manner as in the first embodiment, and a compensation pattern for converging the residual shake is found using feedback control of the shake angular velocity. Note that the start position of the compensation amount is set back by two shake periods from the end point arrival time. 15 and 16 show the calculation results of the compensation amount patterns on the X and Y axes.

[0048] (Steady-state simulation) This compensation pattern was applied to the virtual acceleration pattern shown in Figures 2 and 3, which was converted into Cartesian coordinates, and then reconverted into polar coordinates, as shown in Figures 17 and 18. Compared to Figures 11 and 12, it can be seen that there are no pulse-like irregularities. This is particularly noticeable on the r-axis. Fig. 19 shows the amount of vibration during and after transport when transport is performed using the vibration prevention patterns of Fig. 17 and Fig. 18. The amount of vibration after transport is sufficiently smaller than that in Fig. 5, and it is clear that vibration prevention is possible. Note that it is slightly larger than the amount of residual vibration caused by the corrected acceleration pattern of Example 1. [Explanation of symbols]

[0049] 1. Rotating crane 11. Boom 2. Turning control device 3 Retraction control device 4. Steady-stop control device 5. Suspended load

Claims

1. A sway control method for a rotary crane, which, when transporting a suspended load from a start point to an end point using a rotary crane having a boom, performs feedforward control to prevent the suspended load from swaying after the load arrives at the end point, A residual swing amount is estimated using a tentative acceleration pattern or a tentative velocity pattern for transporting the suspended load from the starting point to the end point; calculating a compensation pattern that cancels the estimated residual shake amount; Applying the compensation pattern to the provisional acceleration pattern or provisional velocity pattern to calculate an acceleration pattern or velocity pattern for transporting the suspended load; A sway prevention control method for a rotary crane, which transports the suspended load using the calculated acceleration pattern or the calculated speed pattern.

2. 2. The sway prevention control method for a rotary crane according to claim 1, wherein, when calculating the acceleration pattern or the speed pattern, the compensation pattern is applied to the provisional acceleration pattern or the provisional speed pattern so that a start time of the compensation pattern is shifted by an integer multiple of a sway period from an arrival time of the suspended load in the provisional acceleration pattern or the provisional speed pattern.

3. the compensation pattern is an acceleration pattern that cancels out an area of ​​a section π on one side of the positive or negative side of a sine wave of the residual shake, or a velocity pattern obtained from the acceleration pattern, and the acceleration pattern is configured with three or more patterns of the same shape but different heights, 3. The anti-sway control method for a rotary crane according to claim 1 or 2, wherein, when calculating the compensation pattern, the sign and height of the pattern of the same shape are changed in units of 1 / 2 of the sway period so that the sum of accelerations, the sum of velocities, and the sum of movement amounts in the pattern of the same shape are 0.

4. 3. The anti-sway control method for a rotary crane according to claim 1, wherein the compensation pattern is an operation amount pattern when feedback control of the sway angular velocity of the suspended load is performed.

5. 5. The anti-sway control method for a rotary crane according to claim 4, wherein the compensation pattern is determined by adjusting a gain of the feedback control so that the residual sway converges over a time period that is at least twice the sway period.

6. 3. The sway prevention control method for a rotary crane according to claim 1 or 2, wherein, when estimating the residual sway amount, an acceleration pattern or a speed pattern capable of preventing the sway of the suspended load when the suspended load is transported in a linear manner is used as the tentative acceleration pattern or the tentative speed pattern.

7. After estimating the residual runout amount, it is determined whether the residual runout amount is 0.01 rad or more; If the estimated amount of the residual shake is 0.01 rad or more in the determination of the residual shake, the compensation pattern is calculated; 3. The anti-sway control method for a rotary crane according to claim 1, wherein, when the estimated amount of the residual sway is less than 0.01 rad in the determination of the residual sway, the tentative acceleration pattern or the tentative speed pattern is used as the acceleration pattern or the speed pattern, and the suspended load is transported.

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