Crane, load swing suppression system, and load swing suppression method

Abstract

The present invention provides a crane, a load swing suppression system, and a load swing suppression method that can effectively suppress the swinging of a suspended load. [Solution] The crane 1 comprises a spreader 10 for lifting a container C, load sensors L1, L2, L3, and L4 for measuring the load of the container C, a first weight moving device 50A and a second weight moving device 50B provided on the spreader 10 for moving a weight 44, and a control unit 30 that moves the weight 44 in the first weight moving device 50A and the second weight moving device 50B based on the load measured by the load sensors L1, L2, L3, and L4.

Description

Technical Field

[0001] One aspect of the present invention relates to a crane.

Background Art

[0002] Conventionally, as described in Patent Document 1, a crane that moves between land and above the hatch of a container ship is known for loading containers onto the container ship. A spreader is suspended from a trolley that moves along a gantry, and the container is gripped by this spreader. In this container, the position of a laser light source provided on the spreader is detected by a sensor provided on the trolley, and thereby the swing displacement amount of the suspended load is detected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described above, detection of the swing of a container (suspended load) has been an issue. By the way, the cargo handling of a container roughly includes two-stage procedures. First, the crane moves the container near the target position. And in the next stage, the crane aligns the container toward the target position. In this first transportation process, the swing of the container occurs. The swing of the container tends to make, for example, the alignment operation in the next stage difficult.

[0005] While control systems and mechanisms to suppress container sway have been considered, further challenges remain in their practical application, and there is room for improvement in terms of usability. For example, it is difficult to effectively suppress asymmetrical sway of a container caused by its eccentricity. Also, if both spreader movement control and container sway suppression control are attempted using the same (common) actuator, the operations for both control mechanisms will conflict. Effective suppression of sway is practically difficult.

[0006] One aspect of the present invention aims to provide a crane, a load swing suppression system, and a load swing suppression method that can effectively suppress the swing of a suspended load. [Means for solving the problem]

[0007] One aspect of the present disclosure is a crane for transporting a suspended load, comprising: a lifting device for suspending the suspended load; a load measuring means for measuring the load of the suspended load; at least one weight movement unit provided on the lifting device for moving a weight; and a control unit for moving the weight in the weight movement unit based on the load measured by the load measuring means.

[0008] In this crane, the load of the suspended load is measured by a load measuring means. Based on the measured load, the control unit moves the weight in the weight movement unit. The weight movement unit is provided on the lifting device, and the movement of the weight can, for example, correct the center of gravity of the lifting device or generate a reaction torque (moment) at a predetermined point on the lifting device. By performing the above control (weight movement control) on the lifting device based on the load of the suspended load, the swing of the suspended load can be effectively suppressed.

[0009] The crane comprises legs, a girder supported by the legs, and a trolley that can traverse along the girder, and the lifting device may be a spreader suspended from the trolley. With this configuration, the swing of the suspended load in the container crane can be effectively suppressed by performing the above control (control of the movement of the weight) based on the planar position on the spreader.

[0010] The spreader may be provided with at least two weight movement parts, and the weights in each weight movement part may be independently movable. With two or more independently movable weights, the center of gravity on the spreader can be easily adjusted.

[0011] The control unit may estimate the center of gravity of the suspended load based on the measurement results of the load measuring means, and control the movement of each weight in the weight movement unit to correct the overall center of gravity including the spreader and the suspended load based on the center of gravity. With this control, the overall center of gravity including the lifting device and the suspended load is corrected, so the swing of the suspended load can be suppressed more reliably.

[0012] The control unit may control the trolley to suppress the swing of the suspended load in the direction of trolley movement. By combining this with the control of the trolley, a synergistic effect can be obtained with the motion control of the weight described above. The effect of suppressing the swing of the suspended load described above is further enhanced.

[0013] The system includes at least one inertial sensor mounted on the spreader, and the weight motion unit is a flywheel device mounted on the spreader that rotates the weight by a motor. The control unit may control the rotation of the weight in the flywheel device based on the measurement results of the load measuring means and the detection results of the inertial sensor. With this configuration, a desired reaction torque can be generated at the position of the weight on the spreader.

[0014] The control unit may calculate the rotational moment at the position of the weight in the weight movement section based on the detection result of the inertial sensor, the measurement result of the load measuring means, and the positional relationship between the load measuring means and the inertial sensor, and control the rotation of the weight in the flywheel device to cancel out the rotational moment. By rotating the weight in the flywheel device, a predetermined reaction torque (moment) can be generated at the position of the weight on the spreader. By controlling the rotation of the weight to cancel out the rotational moment at the weight's position, the swing of the suspended load can be suppressed more reliably.

[0015] Another aspect of the present invention is a load swing suppression system applied to a crane that lifts and transports a load using a lifting device, comprising: a load measuring means for measuring the load of the load; at least one weight movement unit provided on the lifting device for moving a weight; and a control unit that moves the weight in the weight movement unit based on the load measured by the load measuring means when the load is lifted by the lifting device.

[0016] A further aspect of the present invention is a method for suppressing load swing in a crane that transports a suspended load while suspending it with a lifting device, wherein the load of the suspended load is measured, and when the suspended load is lifted by the lifting device, a weight provided on the lifting device is moved based on the measured load.

[0017] The load swing suppression system and load swing suppression method can achieve the same effects and functions as the crane described above. [Effects of the Invention]

[0018] According to some aspects of the present invention, the swaying of a suspended load can be effectively suppressed. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 shows the overall configuration of a crane according to one embodiment of the present invention. [Figure 2]FIG. 2 is a perspective view showing a spreader (lifting tool) and a suspended load suspended by the spreader. [Figure 3] FIG. 3 is a block diagram showing the main configuration related to the swing suppression control of the crane of the first embodiment. [Figure 4] FIG. 4 is a plan view of a spreader having a weight moving part in the crane of FIG. 3. [Figure 5] FIG. 5(a) is a diagram showing the case where the center of gravity of the suspended load coincides with the planar center position of the suspended load, and FIG. 5(b) is a diagram showing the case where the center of gravity of the suspended load is different from the planar center position of the suspended load. [Figure 6] FIG. 6 is a flowchart of the center of gravity correction control of the suspended load executed by the control unit. [Figure 7] FIG. 7 is a diagram showing an example of the corrected center of gravity as a result of the center of gravity correction control of the suspended load. [Figure 8] FIGS. 8(a) and 8(b) are diagrams for explaining the swing suppression effect in the case of combining the movement control of the trolley. [Figure 9] FIG. 9 is a block diagram showing the main configuration related to the swing suppression control of the crane of the second embodiment. [Figure 10] FIG. 10 is a plan view of a spreader having a weight moving part in the crane of FIG. 9. [Figure 11] FIG. 11(a) is a diagram showing the swing direction of the suspended load when the suspended load is eccentric, and FIG. 11(b) is a diagram showing an example of the swing suppression control using the reaction torque. [Figure 12] FIG. 12 is a flowchart of the swing suppression control of the suspended load executed by the control unit. [Figure 13] FIG. 13(a) is a diagram for explaining the calculation of the rotational moment regarding the position of one weight, and FIG. 13(b) is a diagram showing an example of the swing suppression control by the generation of the reaction torque at the position (predetermined point).

Embodiments for Carrying Out the Invention

[0020] Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0021] First, with reference to Figure 1, an overview of the crane according to an embodiment of the present invention will be described. As shown in Figure 1, the crane 1 is a crane that transports a container (suspended load) C placed inside a container ship 90 (vessel) moored alongside a quay 91. The container C is, for example, an ISO standard container. The container C has a long rectangular parallelepiped shape and has a predetermined length in its longitudinal direction, for example, 20 feet or 40 feet. The crane 1 in this embodiment is, for example, a bridge crane. The crane 1 comprises legs 11, girders 12 (guide members), a trolley 7, a driver's cab 14, and a spreader (lifting device) 10.

[0022] Crane 1 loads containers C into the space inside the container ship 90 (see underdeck UD in the figure) and also loads containers C onto the upper side of deck DK (see ondeck OD in the figure). Crane 1 grabs containers C loaded on the quay 91 with spreader 10, lifts them, transports them onto the container ship 90, and loads containers C onto the loading area P. In other words, crane 1 transports containers C while lifting them with spreader 10. The loading area P is, for example, the top surface of already loaded containers C, the cell guides inside the container ship 90, the bottom surface of the container ship 90, or on deck DK. The cell guides are provided on the inner wall surface of the side wall of the container ship 90 so as to extend in the vertical direction.

[0023] The legs 11 are installed on the ground of the quay 91, and in a view in the direction of travel they have an H shape, extending upward and supporting the entire crane 1. The legs 11 form a pair, left and right, and each has a traveling device 11a at its base end. The traveling device 11a is driven by a traveling motor 23 (see Figure 3) and travels along rails installed on the ground in the direction of travel. The direction of travel is horizontal along the quay. This allows the legs 11 to travel along the quay 91 in the direction of travel.

[0024] The girder 12 is supported by the legs 11. The girder 12 extends from the legs 11 in a longitudinal direction (left-right direction in Figure 1) that intersects the direction of travel in the horizontal direction. The longitudinal direction is the horizontal direction between the sea side and the land side. Supported by the legs 11, the girder 12 extends above the container ship 90 and beyond the quay 91 toward the container ship 90. In other words, the girder 12 extends from the quay 91 toward the sea. The girder 12 is also called a boom.

[0025] The trolley 7 is capable of traversing along the girder 12. The trolley 7 traverses by the drive of a traversing motor 21 (see Figure 3). As the trolley 7 moves, the driver's cab 14 and the spreader 10 are also capable of moving in the longitudinal direction, which is the extension direction of the girder 12 (see direction MV1 in the figure). The trolley 7 is equipped with drums 8A and 8B (see Figure 2) that rotate in forward and reverse directions by a drum drive motor, and the spreader 10 is suspended via wire ropes 9 (suspension members) wrapped around the drums.

[0026] The spreader 10 is suspended from the trolley 7 via a wire rope 9, and can be raised or lowered by the wire rope 9. The spreader 10 can lock onto the container C to be lifted and handles the loading and unloading of the container C. In other words, the spreader 10 lifts the container C. The spreader 10 is suspended via a sheave 18 (see Figure 2) around which the wire rope 9 is wrapped, and can be raised and lowered by the forward and reverse rotation of a drum in the machine room 19.

[0027] Next, the configuration of the spreader 10 will be described with reference to Figure 2. Figure 2 is a perspective view of the spreader 10. As shown in Figure 2, the spreader 10 is a cargo handling mechanism that extends generally horizontally. The spreader 10 can be raised and lowered by a wire rope 9 and is used for handling containers C. The spreader 10 has a main body 15. The main body 15 grips the container C with gripping mechanisms such as flipper claws provided at the four corners. The main body 15 also fixes the container C with locking parts such as lock pins provided at the four corners. For example, the spreader 10 can lock and hold the container C by having a locking piece formed at the lower end of a lock pin enter holes formed at the four corners of the upper surface of the container C and rotate. The locking mechanism (structure) of the spreader 10 to the container C is not limited to this, and other known mechanisms (structures) may be used.

[0028] At least near both ends of the main body 15, in a plan view, it has a shape substantially identical to the shape of the top surface of the container C. The main body 15 has the aforementioned sheaves 18 around which the wire rope 9 is wrapped, located above the four corners. The main body 15 is operated by the hoisting and lowering of drums 8A and 8B, which are provided at arbitrary positions on the crane 1. Drum 8A is a hoisting drum that moves the main body 15 up and down. Drum 8B is a tilting drum that adjusts the angle of the main body 15. The main body 15 is positioned on the container C when the spreader 10 locks the container C. In this embodiment, the short side direction of the spreader 10 and the container C is referred to as the X-axis direction and is substantially parallel to the direction of movement of the trolley 7 (direction MV1 in Figure 1). The longitudinal direction of the spreader 10 and the container C is referred to as the Y-axis direction and is substantially parallel to the direction of travel of the legs 11. Furthermore, the Z-axis direction, which is perpendicular to both the X-axis and Y-axis directions, is generally vertical (up and down). The direction in which the main body 15 moves downward (i.e., descends) is considered to be the positive direction along the X-axis.

[0029] Next, with reference to Figures 3, 4, and 5, the configuration for suppressing the sway of the container C according to the first embodiment will be described. The crane 1 according to this embodiment is equipped with a configuration that can suppress the sway while taking into account the eccentricity of the container C. Figure 3 is a block diagram showing the main configuration related to the sway suppression control of the crane 1. Figure 4 is a plan view of the spreader 10 equipped with a weight moving device (weight movement part) in the crane 1. Figure 5(a) shows the case where the center of gravity of the container C coincides with the planar center position of the spreader 10, and Figure 5(b) shows the case where the center of gravity of the container C is different from the planar center position of the spreader 10. Note that in the plan views of the spreader 10 from Figure 4 onward, the outer shape of the container C, shown by dashed lines, is intentionally drawn to be slightly larger than the outer shape of the spreader 10. The shape and size of the outer shape of the container C may be substantially the same as or different from the shape and size of the outer shape of the spreader 10 in a plan view.

[0030] As shown in Figure 3, the crane 1 is equipped with a load swing suppression system 100. In other words, the crane 1 is equipped with a load swing suppression system 100. The load swing suppression system 100 includes four load sensors L1, L2, L3, and L4 as load measuring means for measuring the load of container C. As shown in Figure 4, each of the load sensors L1, L2, L3, and L4 is provided, for example, at the four corners of the main body 15 of the spreader 10. Each of the load sensors L1, L2, L3, and L4 is, for example, a known load cell and is attached to a locking part such as a lock pin provided at the four corners of the spreader 10. Each of the load sensors L1, L2, L3, and L4 may be attached to a gripping mechanism such as a flipper claw.

[0031] Each of the load sensors L1, L2, L3, and L4 transmits a signal indicating the measured load to the control unit 30. Each load sensor may communicate with the control unit 30 via a wired connection or wirelessly. In this embodiment, the load of container C is measured by the sum of the four load sensors L1, L2, L3, and L4, and the planar load distribution is also measured based on the measurement results of each load sensor. Note that the load sensors are not limited to load cells; piezoelectric load sensors or the like may be used.

[0032] As shown in Figure 4, a first weight moving device 50A and a second weight moving device 50B are installed on, for example, the upper surface of the main body 15 of the spreader 10, extending in the Y-axis direction. The first weight moving device 50A and the second weight moving device 50B have, for example, the same configuration. The first weight moving device 50A and the second weight moving device 50B are fixed to both ends of the main body 15 in the X-axis direction and are spaced apart from each other in the X-axis direction. Each of the first weight moving device 50A and the second weight moving device 50B corresponds to the weight moving part described in the claims.

[0033] The first weight moving device 50A includes a base plate 41 fixed on the main body 15 and extending in the Y-axis direction, a pair of support parts 42 arranged spaced apart in the Y-axis direction on the base plate 41, and a ball screw 43 rotatably supported by the pair of support parts 42. A weight 44 is provided on the base plate 41, whose position in the X-axis direction is restricted, and which can slide (move) in the Y-axis direction by screwing its internal female threaded portion into the ball screw 43. A redundant explanation of the configuration of the second weight moving device 50B will be omitted.

[0034] The first weight moving device 50A includes a first weight moving motor 51 that moves the weight 44 along the Y-axis direction by rotating a ball screw 43. The second weight moving device 50B includes a second weight moving motor 52 that moves the weight 44 along the Y-axis direction by rotating a ball screw 43. The load swing suppression system 100 includes a container center of gravity correction mechanism 40 having these first weight moving devices 50A and second weight moving devices 50B. The load swing suppression system 100 includes a control unit 30 that moves the two weights 44 independently by controlling the first weight moving motor 51 and the second weight moving motor 52. In Figure 3, only the first weight moving motor 51 and the second weight moving motor 52, which are controlled by the control unit 30, are shown as components of the container center of gravity correction mechanism 40.

[0035] The control unit 30 is located, for example, in the machine room 19 (see Figure 1). The control unit 30 is an electronic control unit composed of a processor such as a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The control unit 30 receives the loads measured by the load sensors L1, L2, L3, and L4, and controls the container center of gravity correction mechanism 40 based on these loads.

[0036] In both the first weight moving device 50A and the second weight moving device 50B, the weight 44 is movable within a predetermined range along the Y-axis. In the first embodiment, the "motion" of the weight 44 means linear reciprocating movement. The predetermined range is, for example, the area between a pair of support parts 42, but can be set or changed as appropriate. The control unit 30 can sense the Y-axis position of each 44 by encoders incorporated in, for example, the first weight moving motor 51 and the second weight moving motor 52. For example, the cumulative number of rotations in each moving motor is converted into a coordinate position on the Y-axis.

[0037] The two weights 44 have the same constant weight (or mass). Each weight 44 can also be called a "mass unit". The weight of each weight 44 can be set as appropriate. The first weight moving device 50A and the second weight moving device 50B are designed to be positioned such that their centers of gravity do not affect (cause eccentricity) the center of gravity of the spreader 10. For example, if the center of gravity of the spreader 10 is shifted from the center O due to the positioning of the first weight moving device 50A and the second weight moving device 50B, the center of gravity may be adjusted to coincide with the center O by installing a counterweight or the like. Alternatively, the shift of the center of gravity from the center O may be taken into consideration during calculations by the control unit 30, and the overall center of gravity correction described later may be performed.

[0038] Furthermore, the device configuration is not limited to the ball screw 43 configuration such as the first weight moving device 50A and the second weight moving device 50B shown in Figure 4, but other known devices may be applied to the container center of gravity correction mechanism 40. For example, a belt may be stretched over a pair of pulleys having a rotation axis extending in the Z-axis direction, and the belt may be moved by rotating one of the pulleys with the drive of a motor. The movement of the belt may allow a weight fixed to a part of the belt to move in the Y-axis direction. Alternatively, a weight fixed to a part of the rack may be moved in the Y-axis direction by the meshing of a rack with a pinion integrated with the output shaft of a motor.

[0039] Container C is stacked in such a way that the position of its center of gravity G in a plan view is as even as possible. Therefore, ideally, as shown in Figure 5(a), the center of gravity G of container C coincides with, or nearly coincides with, the position of the planar center O of spreader 10. In that case, the direction D1 of the inertial force generated by the traverse of trolley 7 coincides with the direction of the swing D2. However, in reality, the center of gravity G of container C may be eccentric. In that case, as shown in Figure 5(b), a "mixed swing" (or "composite swing") can occur, consisting of two types of swing: a swing in the same uniaxial (X-axis) direction D2 as the direction of the inertial force D1, and a swing due to rotational moment. More specifically, the swing due to rotational moment is caused by the difference in the amount of swing between a large rotational moment MRa that occurs on the side of the center of gravity G with respect to the center O, and a small rotational moment MRb that occurs on the opposite side (asymmetry of swing around the center O). Such eccentricity of container C caused rotation of container C (and spreader 10), making it difficult to align or insert container C with the cell guide (especially in under-deck UD cargo handling).

[0040] The load swing suppression system 100 and the crane 1 equipped therewith of this embodiment achieve suppression of the swing of the container C. As shown in Figure 3, the load swing suppression system 100 can also suppress swing by controlling the traverse motor 21, the small swing motor 22, and the travel motor 23 used in the prior art (these can be used in combination). The control unit 30 controls the traverse position and traverse speed of the traverse motor 21 to suppress swing in the X-axis direction (direction of movement of the trolley 7). The control unit 30 controls the small swing swing amount and the small swing power cylinder position of the small swing motor 22 to suppress swing (rotation) around the Z-axis. The control unit 30 controls the travel position and travel speed of the travel motor 23 to suppress swing in the Y-axis direction (direction of travel of the leg portion 11).

[0041] Next, with reference to Figures 6 and 7, the center of gravity correction control (load swing suppression method) of container C performed by the control unit 30 of crane 1 will be described. The following control is performed during the first of the two stages of cargo handling, that is, while crane 1 holds container C and moves container C to near the target position. The following control may also be performed after crane 1 has moved container C to near the target position. First, the control unit 30 controls the first weight moving motor 51 and the second weight moving motor 52 to move the two weights 44 to their initial position (the center position in the Y-axis direction shown in Figure 4) (step S11). Only this step S11 may be performed before crane 1 holds container C.

[0042] The control unit 30 acquires the measured load values ​​(measurement results) transmitted from the four load sensors L1, L2, L3, and L4 (step S12). The control unit 30 calculates the sum of the four loads (weights) (step S13). This allows the control unit 30 to obtain the weight of container C. Subsequently, the control unit 30 calculates the position of the center of gravity G of container C in a planar manner (step S14). This calculation can be performed by a known method. For example, the position of the center of gravity G can be determined by adding four vectors based on the measurement results from each load sensor and the planar position information of each load sensor, with the position of load sensor L1 as the origin. Through the processing in steps S12 and S14, the control unit 30 estimates the position of the center of gravity of container C based on the measurement results from load sensors L1, L2, L3, and L4.

[0043] Next, the control unit 30 determines whether or not there is eccentricity (step S15). In this determination process, for example, the control unit 30 can determine that there is eccentricity if the center of gravity G is located outside the range of a circle (a circle with a certain radius) with respect to the position of the center O. In this case, the certain radius is the threshold for determining eccentricity. If the control unit 30 determines that there is no eccentricity (step S15; NO), the control unit 30 terminates the control without moving any of the weights 44.

[0044] If the control unit 30 determines that there is eccentricity (step S15; YES), it calculates the target position of each weight 44 (step S16). Based on the position of the center of gravity G obtained in step S14, the control unit 30 calculates the target position of each weight 44 in such a way as to correct the overall center of gravity including the spreader 10 and the container C (step S16). As shown in Figure 7, the control unit 30 uses, for example, the vector from the origin to the position of the weight 44 of the first weight moving device 50A and the vector from the origin to the position of the weight 44 of the second weight moving device 50B as manipulated variables, and the vector from the origin to the overall operating center of gravity TG as a controlled variable, and determines the target position of each weight 44 so that the position of the center of gravity obtained by summing these coincides with the center O of the spreader 10. The operating center of gravity TG in the figure means the overall center of gravity including the spreader 10 and the container C (the combined center of gravity of the spreader 10 and the container C).

[0045] Then, the control unit 30 moves each weight 44 to the target position (step S17). By correcting the operating center of gravity TG, which is the combined center of gravity, to the center O of the spreader 10 (which is also the center of the container C), the overall sway can be suppressed even if the container C is eccentric. Through the above center of gravity correction control, the occurrence of sway caused by the eccentricity of the container C can be suppressed. In addition, in conjunction with the above series of center of gravity correction controls, the control unit 30 may also control the traverse position and traverse speed of the traverse motor 21 to suppress sway in the X-axis direction (i.e., the direction MV1) (see Figures 8(a) and 8(b)). That is, the control unit 30 controls the trolley 7 so as to suppress the sway of the container C in the direction of movement of the trolley 7.

[0046] In this embodiment of the load sway suppression method, the load of container C is measured, and when container C is suspended by the spreader 10, the weight 44 provided on the spreader 10 is moved based on the measured load.

[0047] According to the crane 1, load swing suppression system 100, and load swing suppression method of this embodiment, the load of container C is measured by load sensors L1, L2, L3, and L4. Based on the measured load, the control unit 30 moves the weights 44 in the first and second weight moving devices 50A and 50B. The first and second weight moving devices 50A and 50B are provided on the spreader 10, and the movement of the weights 44 can, for example, correct the center of gravity of the spreader 10 or generate a reaction torque (moment) at a predetermined point on the spreader 10. By performing the above control (motion control of the weights 44) in the spreader 10 based on the load of container C, the swing of container C can be effectively suppressed. Furthermore, the swing time can be shortened, and insertion into the cell guide described above can be performed easily and quickly.

[0048] With a crane 1 equipped with a spreader 10 suspended from a trolley 7, the above control (motion control of the weight 44) can be performed based on the planar position on the spreader 10, thereby effectively suppressing the swaying of the container C in the container crane.

[0049] The two independently movable weights 44 allow for easy adjustment of the center of gravity on the spreader 10.

[0050] The control unit 30 controls the movement of the weights in the first and second weight moving devices 50A and 50B to correct the overall center of gravity including the spreader 10 and the container C. This control corrects the overall center of gravity including the spreader 10 and the container C, thereby more reliably suppressing the sway of the container C. It also makes it possible to suppress asymmetric sway.

[0051] The control unit 30 controls the trolley 7 to suppress the swaying of the container C in the direction of trolley movement. By combining this control with the control of the trolley 7, a synergistic effect is obtained with the motion control of the weight 44 described above. The effect of suppressing the swaying of the container C described above is further enhanced.

[0052] Next, with reference to Figures 9 and subsequent figures, a crane 1 equipped with a load swing suppression system 100A according to the second embodiment will be described. As shown in Figures 9 and 10, the load swing suppression system 100A includes four inertial sensors N1, N2, N3, and N4 located at the four corners of the spreader 10. Each inertial sensor is, for example, a known inertial measurement unit (IMU). In Figure 10, in order to enable a planar illustration, each of the inertial sensors N1, N2, N3, and N4 is shown in a position adjacent to the load sensors L1, L2, L3, and L4, but their planar positions are the same. Note that each of the inertial sensors N1, N2, N3, and N4 may be adjacent to the load sensors L1, L2, L3, and L4.

[0053] On the upper surface of the main body 15 of the spreader 10, for example, a first flywheel device 70A, a second flywheel device 70B, a third flywheel device 70C, and a fourth flywheel device 70D are installed at equal distances around the center O. These flywheel devices are torque generators having the same configuration. The first flywheel device 70A includes a first wheel motor 71 and a first weight 75A. The second flywheel device 70B includes a second wheel motor 72 and a second weight 75B. The third flywheel device 70C includes a third wheel motor 73 and a third weight 75C. The fourth flywheel device 70D includes a fourth wheel motor 74 and a fourth weight 75D. Each flywheel device can apply a reaction torque to the spreader 10 due to the reaction force associated with the rotational speed fluctuations.

[0054] For example, the first flywheel device 70A and the third flywheel device 70C are arranged symmetrically with respect to a vertical line (Z-axis line) passing through the center O. The output shafts of the first wheel motor 71 and the third wheel motor 73 are arranged, for example, on a straight line passing through the center O and parallel to the Y-axis. The output shafts of the second wheel motor 72 and the fourth wheel motor 74 are arranged, for example, on a straight line passing through the center O and parallel to the X-axis. Each of these flywheel devices corresponds to the weight motion section described in the claims.

[0055] For example, the inertia of each flywheel device may be designed so that only the reaction torque at the initial stage of rotation of each wheel motor can be extracted. For example, each wheel motor may be designed so that the reaction torque in the latter half of rotation is dampened earlier. The magnitude of the reaction torque is controlled by the voltage applied to each wheel motor.

[0056] The load sway suppression system 100A includes a container sway suppression mechanism 60 having a first flywheel device 70A, a second flywheel device 70B, a third flywheel device 70C, and a fourth flywheel device 70D. The load sway suppression system 100A includes a control unit 30A that controls the first wheel motor 71, the second wheel motor 72, the third wheel motor 73, and the fourth wheel motor 74 to rotate each of the four flywheels independently. In Figure 9, only the four wheel motors controlled by the control unit 30A are shown as components of the container sway suppression mechanism 60.

[0057] Furthermore, the flywheel device is not limited to the configuration described above; other known devices may be applied to the container sway suppression mechanism 60 as torque generators. For example, a torque generator including a motor, a disc (weight) rotated by the motor, and a multi-stage brake that clamps the disc may be applied. Such a torque generator can also be considered a type of flywheel device in which a motor rotates a disc (weight). In this case, the disc, which has inertia, is rotated at a constant speed by the motor, and when it is desired to extract reaction torque, one can select the brake to be applied from the multi-stage brakes according to the desired amount and direction of torque to be extracted. For example, when it is desired to extract a moderate amount of reaction torque, an intermediate brake located between the inner brake section closest to the center of rotation and the outer brake section furthest from the center of rotation should be applied.

[0058] As shown in Figure 11(a), when container C is eccentric, an asymmetrical amount of rotation (see rotation amount in rotation direction Ra and rotation amount in rotation direction Rb) may occur around the vertical axis AX passing through the center O. The small swing motor 22 shown in Figure 9 can generate a horizontal canceling input perpendicular to the vertical axis AX, but it cannot control the oscillation in accordance with the above asymmetrical state.

[0059] In the load swing suppression system 100A of this embodiment and the crane 1 equipped therewith, the swing of the container C is suppressed, similar to the first embodiment. As shown in Figure 11(b), the rotation of each weight in each flywheel device generates a reaction torque at the position of each weight, and as a result, a relatively large amount of rotation (rotational moment) in the rotation direction Ra and a relatively small amount of rotation (rotational moment) in the rotation direction Rb can be canceled out.

[0060] Referring to Figures 12, 13(a), and 13(b), the control of container C to suppress sway (load sway suppression method) performed by the control unit 30A of crane 1 will be described. The following control is performed during the first of the two stages of cargo handling, that is, while crane 1 holds container C and moves container C to near the target position. The following control may also be performed after crane 1 has moved container C to near the target position.

[0061] Initially, each flywheel device is stopped. In the following explanation, the control of the first wheel motor 71 will be described using only the first flywheel device 70A as an example. First, the control unit 30A acquires the measured load values ​​(measurement results) transmitted from the four load sensors L1, L2, L3, and L4 (step S21), and further acquires the measured inertia values ​​(measurement results) transmitted from the four inertia sensors N1, N2, N3, and N4 (step S22). The measured inertia values ​​can be decomposed into acceleration in the X-axis direction and acceleration in the Y-axis direction. Next, the control unit 30A calculates the inertial force at each of the four corners (step S23). At this time, the control unit 30A calculates the inertial force in the X-axis direction and the inertial force in the Y-axis direction by multiplying the weights m1 and m2 of mass point 1 at the corner where inertia sensor N1 is installed and mass point 2 at the corner where inertia sensor N2 is installed by the acceleration. The inertial forces in the X-axis direction (Fx1, Fx2) are calculated by multiplying mass 1 by Fx1 = m1 × ax1, and mass 2 by Fx2 = m2 × ax2. The calculation of the inertial forces in the Y-axis direction (Fy1, Fy2) is the same. Note that only the rotational moment in the X-axis direction can be canceled out by the first flywheel device 70A, so it is also acceptable to calculate only the inertial forces in the X-axis direction. (The inertial forces in the Y-axis direction can be canceled out by the second flywheel device 70B or the fourth flywheel device 70D.)

[0062] Next, the control unit 30A calculates the rotational moment at the position of each flywheel device (step S24). With respect to the X-axis direction, the control unit 30A calculates the rotational moment by multiplying the inertial force calculated in step S23 by the arm of the moment (arm q1 shown in Figure 13(a)). Then, the control unit 30A calculates the reaction torque at the first flywheel device 70A so as to cancel out the rotational moment calculated in step S24 (step S25). As the reaction torque that cancels out the rotational moment calculated in step S24, the control unit 30A calculates the value obtained by dividing the rotational moment by the arm q2 related to the position of the first weight 75A.

[0063] Then, the control unit 30A controls the first wheel motor 71 to rotate the first weight 75A and apply a reaction torque (step S26). The applied voltage for generating the reaction torque can be calculated from known models such as the applied voltage and torque characteristics. As shown in Figure 13(b), the rotational moment causing the wobble of the container C is canceled out by the application of the reaction torque RT. The processes in steps S22 to S26 are repeatedly executed at a predetermined control cycle. The control unit 30A terminates the series of controls when the cargo handling is completed (step S27; YES).

[0064] Thus, in the load sway suppression method of the second embodiment, the load of container C is measured, and when container C is suspended by the spreader 10, the first weight 75A etc. provided on the spreader 10 is moved based on the measured load.

[0065] In the second embodiment, the crane 1, load swing suppression system 100A, and load swing suppression method of this embodiment can also effectively suppress the swing of the container C by performing the above control (weight rotation control) in the spreader 10 based on the load and inertia of each point of the container C.

[0066] Furthermore, the control unit 30A controls the rotation of each weight in each flywheel device based on the measurement results of the load sensors L1, L2, L3, and L4 and the detection results of the inertial sensors N1, N2, N3, and N4. With this configuration, a desired reaction torque can be generated at the position of each weight on the spreader 10.

[0067] Furthermore, by controlling the rotation of each weight to counteract the rotational moment at each weight's position, the sway of container C can be suppressed more effectively. Since this control is independent of the operation of the wire rope 9, there is no conflict of operation, and cargo handling efficiency can be improved.

[0068] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the first embodiment, a pair of weights movable in the X-axis direction may be installed to increase the degree of freedom of center of gravity correction. Alternatively, only one weight 44 (weight moving device) may be installed on the spreader 10.

[0069] In the second embodiment, the number of inertial sensors on the spreader 10 may be one, two, three, or five or more. The number of flywheel devices (torque generators) on the spreader 10 may be one, two, three, or five or more.

[0070] In either of the first and second embodiments described above, the load swing suppression systems 100 and 100A are not limited to a configuration in which they are incorporated (applied) to the crane 1 from the outset. The load swing suppression systems 100 and 100A may be retrofitted (introduced) to an existing crane. In that case, for example, load sensors, inertia sensors, weight motion units, and configurations related to the control of the weight motion units would be added to the existing crane.

[0071] For example, the overall structure of crane 1 shown in Figure 1 may be modified as appropriate. Furthermore, the present invention is not limited to container cranes as in the above embodiment, but may be applied to other types of cranes such as RTG cranes and jib cranes. [Explanation of Symbols]

[0072] 1...Crane, 7...Trolley, 9...Wire rope, 10...Spreader (lifting device), 12...Girder, 30,30A...Control unit, 44...Weight, 50A...First weight moving device (weight movement unit), 50B...Second weight moving device (weight movement unit), 100,100A...Load swing suppression system, 70A...First flywheel device (weight movement unit), 70B...Second flywheel device (Weight movement section), 70C...Third flywheel device (weight movement section), 70D...Fourth flywheel device (weight movement section), 75A...First weight, 75B...Second weight, 75C...Third weight, 75D...Fourth weight, C...Container (suspended load), L1, L2, L3, L4...Load sensors (load measuring means), N1, N2, N3, N4...Inertial sensors, G...Center of gravity, O...Center.

Claims

1. A crane for transporting suspended loads, A lifting device for suspending the aforementioned load, A load measuring means for measuring the load of the suspended load, The aforementioned suspension device is provided with at least one weight movement part for moving the weight, A crane comprising: a control unit that moves a weight in the weight movement unit based on the load measured by the load measuring means.

2. Legs and, The girder supported by the aforementioned leg portion, A trolley that can traverse along the girder, The crane according to claim 1, wherein the lifting device is a spreader suspended from the trolley.

3. At least two of the weight movement parts are provided on the spreader, The crane according to claim 2, wherein the weights are independently movable in each of the weight movement parts.

4. The control unit, Based on the measurement results of the load measuring means, the center of gravity of the suspended load is estimated. The crane according to claim 3, wherein the movement of each of the weights in the weight movement section is controlled to correct the overall center of gravity including the spreader and the suspended load based on the aforementioned center of gravity position.

5. The control unit controls the trolley so as to suppress the swing of the suspended load in the direction of movement of the trolley, according to claim 4.

6. The spreader is equipped with at least one inertial sensor, The aforementioned weight movement unit is a flywheel device provided on the spreader, which rotates the weight using a motor. The crane according to claim 2, wherein the control unit controls the rotation of the weight in the flywheel device based on the measurement result of the load measuring means and the detection result of the inertial sensor.

7. The control unit, Based on the detection result of the inertial sensor, the measurement result of the load measuring means, and the positional relationship between the load measuring means and the inertial sensor, the rotational moment at the position of the weight in the weight movement section is calculated. The crane according to claim 6, wherein the rotation of the weight in the flywheel device is controlled to counteract the rotational moment.

8. A load swing suppression system applied to a crane that lifts a load using a lifting device and transports the said load, A load measuring means for measuring the load of the suspended load, The aforementioned suspension device is provided with at least one weight movement part for moving the weight, A load swing suppression system comprising: a control unit that moves a weight in the weight movement unit based on the load measured by the load measuring means when the load is suspended by the lifting device;

9. A method for suppressing load swing in a crane that lifts a load using a lifting device and transports the said load, The load of the suspended load is measured, A method for suppressing load swing, comprising moving a weight provided on the lifting device based on the measured load when the load is lifted by the lifting device.

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