Method and system for suppressing sway of suspended load

Abstract

To provide a suspended load oscillation suppression method and a suspended load oscillation suppression system which are capable of reducing the oscillation of a suspended load, suspended from a floating crane with a simple structure without being restricted by the size of the floating crane or the weight of the suspended load, and the like.SOLUTION: A suspended load oscillation suppression method includes a wave height measurement step of measuring the height and a cycle of a wave, a hull oscillation calculation step of calculating the oscillation amount of a hull which is the oscillation amount of a floating crane 3 based on the wave height and the cycle, a suspended load oscillation calculation step of calculating the oscillation amount of the suspended load which is the oscillation amount of a pile 2 based on the hull oscillation amount, and an oscillation reduction step of vertically moving a weight suspended from a crane 31 between a tip of the crane 31 and the pile 2 in accordance with the oscillation amount of the suspended load.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a load swing suppression method and a load swing suppression system for suppressing swings of a suspended load on a crane ship. [Background technology]

[0002] When loading and unloading cargo using a crane ship, the rocking of the crane ship can cause the suspended load to sway, making it difficult to lower the load to the desired location. For example, when driving piles into the bottom of the water using a pile gripper, the piles suspended by the crane ship must be set (set) into the pile gripper, but if the piles sway, this makes it difficult to set them in place. For example, Patent Document 1 discloses a method for reducing the rocking of a crane ship by connecting a mooring reaction member installed on the bottom of the water to the crane of the crane ship via a wire, with the aim of reducing the rocking of the suspended load. Furthermore, Patent Document 2 discloses a method for suppressing the rocking of a suspended load by controlling the rotation speed of a winch that raises and lowers the suspended load via a crane in accordance with the rocking of the crane ship. However, to suppress the motion of a heavy load such as a monopile using the motion reduction method of Patent Document 1, a crane ship would need to be large in size depending on the weight of the load, and the reaction material used to suppress the motion of the crane ship would also need to be large in size. As a result, constructing and installing such a large-scale reaction material requires time and money. Furthermore, since the motion reduction method using a reaction material can only suppress motion in a specific direction determined by the relative positions of the crane ship and the reaction material, there is a risk that the motion reduction effect will not be achieved depending on the direction of the crane boom. Furthermore, the motion reduction method of Patent Document 2 predicts the amount of motion of the crane ship and controls the rotation speed of the winch, but when motion occurs suddenly, there is a risk that the winch control will not be able to keep up. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-070025 [Patent Document 2] Patent Publication No. 2021-091529 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to propose a method and system for suppressing the swaying of a load suspended from a crane vessel that can reduce the swaying of a load suspended from the crane vessel with a simple configuration, without being limited by the size of the crane vessel or the weight of the suspended load, etc. [Means for solving the problem]

[0005] The method for suppressing suspended load sway of the present invention for solving the above-mentioned problems comprises a wave height measurement step of measuring the wave height and period of waves; a hull sway calculation step of calculating the amount of sway of the crane ship, which is the amount of sway of the crane ship, based on the wave height and period; a suspended load sway calculation step of calculating the amount of sway of the load, which is the amount of sway of the suspended load, based on the amount of sway of the hull; and a sway reduction step of moving a weight suspended by the crane between the tip of the crane and the suspended load up and down in accordance with the amount of sway of the load. The load motion suppression system of the present invention includes a motion suppression device provided between the tip of the crane and the suspended load, a wave height meter that measures the wave height and period, calculation means that calculates the amount of motion of the suspended load based on the wave height and period, and control means that controls the motion suppression device. The motion suppression device has a pair of electromagnets spaced apart from each other above and below, and a weight that moves up and down between the pair of electromagnets due to the magnetic force of the electromagnets, and the control means controls the electromagnets so that the weight moves up and down in accordance with the amount of motion. According to this method and system for suppressing the swing of a suspended load, the swing of the suspended load can be reduced by moving the weight suspended from the crane vessel up and down, eliminating the need for large-scale facilities. Furthermore, the amount of swing of the suspended load is calculated from the direction and height of the crane boom based on the amount of swing of the crane vessel calculated from the wave height and period. This allows the up and down movement of the weight to be controlled in accordance with the swing of the suspended load, resulting in effective suppression of the swing of the suspended load. Furthermore, because the swing of the suspended load can be reduced simply by moving the weight up and down, this is also effective against momentary swings. Reducing the swing of the suspended load in this way improves the operating efficiency of the crane vessel, shortening construction time, and reducing construction costs.

[0006] In addition, in the hull sway calculation process, the hull sway amount can be calculated from the vertical translational movement amount of the crane ship, the rotation amount around the hull longitudinal axis of the crane ship, and the rotation amount around the hull minor axis of the crane ship. In the load sway calculation step, the load sway amount may be calculated based on the ship hull sway amount, the elevation angle of the crane boom, and the horizontal angle of the boom. Calculating the load sway amount according to the crane tip position in this manner enables more accurate estimation of the load sway amount. Furthermore, the sway reducing force caused by the movement of the weight in accordance with the amount of sway of the suspended load may be calculated based on the mass and acceleration of the weight, the amount of sway of the suspended load, and the mass of the suspended load. When the motion reduction device is suspended from the crane by a device hoisting wire, it is desirable that the load hoisting wire that suspends the load passes through a through hole formed in the center of the motion reduction device without contacting it. [Effects of the Invention]

[0007] The method and system for suppressing the sway of a suspended load of the present invention can reduce the sway of a suspended load suspended from a crane vessel with a simple configuration, without being limited by the size of the crane vessel or the weight of the suspended load, etc. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a front view showing an embodiment of the water facility of the present invention. [Figure 2] (a) and (b) are side views showing the installation of piles. [Figure 3] FIG. 1 is a schematic diagram showing an overview of a suspended load sway suppression system. [Figure 4] 1A and 1B are diagrams showing an overview of a motion reduction device, in which FIG. 1A is a side view and FIG. 1B is an enlarged side view. [Figure 5] FIG. 1 is a schematic diagram showing an example of a wave height meter. [Figure 6] 10 is a flowchart showing a method for suppressing swaying of a suspended load. DETAILED DESCRIPTION OF THE INVENTION

[0009] In this embodiment, we will explain the construction of a foundation structure for an offshore wind power generation facility (floating facility) 1. The floating facility of this embodiment is shown in Fig. 1. As shown in Fig. 1, the offshore wind power generation facility 1 of this embodiment is made of a so-called monopile foundation in which columns 12 of a wind turbine 11 are supported on pile foundations 13. The construction of piles 2, which constitute the foundation structure of an offshore wind power generation facility (floating facility) 1, is carried out by driving the piles 2, held by pile grippers 33 attached to a crane ship 3, into the waterbed (ground G). Figure 2 shows the installation of the piles 2. When setting the piles 2 in the pile grippers 33, the piles 2 are suspended from the crane ship 3's crane 31. As shown in Figures 2(a) and 2(b), the piles 2 suspended by hoisting wires 32 extending from the crane 31 sway in conjunction with the swaying of the crane ship 3 caused by waves (heaving and pitching in Figure 2). Setting the piles 2 in a swaying state is difficult. Therefore, in this embodiment, a load sway suppression method using a load sway suppression system 4 is used to reduce the swaying of the piles 2 suspended from the crane 31, thereby improving the efficiency of the pile 2 installation work. Figure 3 shows an overview of the load sway suppression system 4 of this embodiment. As shown in FIG. 3, the suspended load motion suppression system 4 includes a motion suppression device 5, a wave height meter 6, a calculation means 7, and a control means 8.

[0010] FIG. 4 shows the motion reduction device 5. As shown in FIG. 4(a), the motion reduction device 5 is provided between the tip of the crane 31 (boom) and the pile 2 (suspended load). As shown in FIG. 4(b), the motion reduction device 5 has a pair of electromagnets 51, 51 spaced apart from each other in the vertical direction, and a weight 52 that moves up and down between the pair of electromagnets 51, 51 due to the magnetic force of the electromagnets 51. In this embodiment, the pair of electromagnets 51, 51 and the weight 52 are housed in a cylindrical container 50. The electromagnets 51 are fixed to the upper and lower ends of the container 50, respectively. The outer diameter of the weight 52 is smaller than the inner diameter of the container 50, and the weight 52 can move up and down between the pair of electromagnets 51, 51 within the container 50. The motion reduction device 5 is suspended from the crane 31 by a device wire 53, which is a wire different from the load wire 32 used to suspend the pile 2. The device wire 53, which runs from the motion reduction device 5 to the lifting jig 21 for the pile 2, is attached to the lower end of the motion reduction device 5. A through-hole 54 is formed in the center of the motion reduction device 5, allowing the load wire 32 to pass through. The inner diameter of the through-hole 54 is larger than the outer diameter of the load wire 32. The hoisting wire 32 passes through the through-hole 54 without contacting it, and is attached to a hoisting jig 21 provided at the upper end of the pile 2 below the motion reduction device 5.

[0011] An example of the wave height meter 6 is shown in Figure 5. As shown in Figure 5, the wave height meter 6 measures the wave height and period of waves at a position away from the crane barge 3. The wave height meter 6 is provided on a buoy or the like installed at a position away from the crane barge 3. The type of wave height meter 6 is not limited, and for example, a GPS wave height meter or an ultrasonic wave height meter can be used. The measurement results of the wave height meter 6 are transmitted to the calculation means 7.

[0012] The calculation means 7 calculates the amount of sway of the pile 2 (amount of sway of the suspended load). The amount of sway of the pile 2 is calculated based on the wave height and period of the waves transmitted from the wave height meter 6. The calculation means 7 stores the amount of hull sway corresponding to the wave height and period, which have been compiled into a database through numerical analysis. Note that half the wave height is the wave amplitude. The amount of hull sway is based on the position (height) of the hull when the wave height is zero (wave amplitude is zero). The calculation means 7 extracts the amount of hull sway based on the data transmitted from the wave height meter 6 from the database and calculates the amount of sway of the suspended load using this amount of hull sway and the direction of the boom (angle of elevation and horizontal angle). After calculating the amount of sway of the suspended load, the calculation means 7 calculates the force required to reduce the sway of the pile 2 (sway reduction force) and the timing for applying this force (action time). The sway reduction force is calculated as a function of the mass of the weight 52, the moving speed and acceleration of the weight 52, and the amount of sway of the suspended load (pile 2). After calculating the vibration reduction force and the duration of action, the calculation results (vibration reduction force and duration of action) are transmitted to the control means 8.

[0013] The control means 8 controls the motion reduction device 5 based on the motion reduction force and duration of action transmitted from the calculation means 7. The control means 8 controls the energization of the electromagnets 51 so that the weight 52 moves up and down. When power is supplied to the electromagnets 51 at one or both ends to generate a magnetic force in the electromagnets 51, a reaction force is generated in the opposite direction to the direction of movement the moment the weight 52 moves, and an impact force is generated when the weight 52 collides with the side of the electromagnet 51 in the direction of movement. The motion reduction force generated in this way is applied up and down via the device wire 53 to reduce the motion of the load (pile 2) suspended by the crane 31. The duration of action of the vibration reduction force is as follows: When the pile 2 vibrates downward, an upward impact force is applied to the pile 2 via the device wire 53 by having the weight 52 collide with the upper electromagnet 51, and an upward reaction force is applied to the pile 2 via the device wire 53 by supplying power to the electromagnets 51 at one or both ends to move the weight 52 downward with an acceleration corresponding to the amount of vibration of the pile 2. On the other hand, when the pile 2 vibrates upward, a downward force is applied to the crane 31 (boom) via the device wire 53 by having the weight 52 collide with the lower electromagnet 51, and an downward reaction force is applied to the crane 31 (boom) via the device wire 53 by supplying power to the electromagnets 51 at one or both ends to move the weight 52 upward with an acceleration corresponding to the amount of vibration of the pile 2.

[0014] This shows a method for suppressing load oscillations using the suspended load oscillation suppression system 4. Fig. 6 shows the steps of the method for suppressing load oscillations. As shown in Fig. 6, the method for suppressing load oscillations of this embodiment includes a waveform measurement step S1, a hull oscillation calculation step S2, a suspended load oscillation calculation step S3, and an oscillation reduction step S4. The waveform measurement step S1 is a step of measuring the wave height and period of waves using a wave height meter 6. The measurement results from the wave height meter 6 are transmitted to the calculation means 7.

[0015] The ship oscillation calculation step S2 is a step of calculating the ship oscillation amount, which is the amount of oscillation of the crane ship 3, based on the wave height and period. In this embodiment, the response amplitude (RAO) for the wave height H and period T is calculated in advance by numerical analysis. h ,RAO r , R.A.O. p ) is calculated and stored in a database, and the amount of ship rolling according to the wave height and period is calculated based on this database. The amount of ship rolling is calculated by calculating the amount of vertical translation of the crane ship 3, the amount of rotation around the hull major axis of the crane ship 3, and the amount of rotation around the hull minor axis of the crane ship 3 (Equations 1 to 3). Ship motion d h =f(H,RAO h (T))=H×RAO h (T): Vertical translation (Heave) Equation 1 d r =f(H,RAO r(T))=H×RAO r (T): Rotation around the hull's longitudinal axis (Roll) Equation 2 d p =f(H,RAO p (T))=H×RAO p (T): Rotation around the hull's minor axis (Pitch) Equation 3 Here, the wave conditions are H: wave height, T: period. h ,RAO r , R.A.O. p ) is the amplitude of ship motion for a wave height of 1 m, and is expressed as a function of the wave period T.

[0016] The suspended load sway calculation step S3 is a step of calculating the suspended load sway amount, which is the amount of sway of the suspended load (pile 2), based on the amount of hull sway. In the suspended load sway calculation step S3, the suspended load sway amount is calculated based on the amount of hull sway and the elevation angle and horizontal angle of the boom of the crane 31 (Equation 4). Amount of hanging load sway δ = f(d h , d r , d p , φ, θ) . Equation 4 Here, the boom conditions of the crane 31 are φ: boom elevation angle, and θ: boom horizontal angle.

[0017] In the vibration reduction step S4, the vibration of the pile 2 is reduced. The vibration of the pile 2 is reduced by moving the weight 52 up and down between the tip of the crane 31 and the pile 2 at an acceleration corresponding to the amount of vibration of the suspended load. By moving the weight 52 up and down at an acceleration corresponding to the amount of vibration of the suspended load, an impact force and a reaction force are generated, thereby reducing the vibration of the pile 2. When the pile 2 is raised, the weight 52 is lowered and hits the lower electromagnet 51, causing a downward impact force to act, and the weight 52 is raised from the lower electromagnet 51, causing a downward reaction force to act. When the pile 2 is lowered, the weight 52 is hit by the upper electromagnet 51, causing an upward impact force to act, and the weight 52 is lowered from the upper electromagnet 51, causing an upward reaction force to act. At this time, the magnitude of the acceleration of the weight 52 is adjusted by adjusting the amount of current passed through the electromagnet 51. The sway reduction force is calculated based on the mass of the weight 52, the moving speed and acceleration of the weight 52, the amount of sway of the suspended load, and the mass of the suspended load (Equation 5). Vibration reduction force Impact force: F im = m v m f(δ, M) / Δt Reaction force: F re = m α m ·f(δ, M) ···Equation 5 Here, the weight conditions are m: mass of the weight, v m : moving speed of the weight, α m : acceleration of the weight movement, Δt: time until the weight comes to rest, and as a condition of the lifting load, M: mass of the pile.

[0018] According to the method for suppressing the swaying of a suspended load and the system for suppressing the swaying of a suspended load 4 of this embodiment, the swaying of the pile 2 can be reduced by moving the weight 52 suspended from the crane ship 3 up and down, thereby making it possible to improve the efficiency of the work of driving the pile 2 without requiring large-scale equipment. In addition, the amount of rocking of the pile 2 is calculated based on the amount of rocking of the crane ship 3, which is calculated from the wave height and period of the waves, so that the rocking of the pile 2 can be effectively suppressed by controlling the up and down movement of the weight 52 in accordance with the rocking of the pile 2. In addition, since the rocking of the pile 2 can be reduced simply by moving the weight 52 up and down, it is possible to effectively reduce instantaneous rocking. By reducing the rocking of the pile 2 in this way, the operating efficiency of the crane ship 3 can be improved, and the construction period and construction costs can be reduced. Furthermore, by calculating the amount of load sway according to the position of the tip of the crane, it is possible to estimate the amount of load sway more accurately. The rolling reduction device 5 has a structure in which the hoisting wire 32 is passed through, and therefore can be installed without changing the structure of the crane 31 or the barge (crane ship 3). Therefore, it can be installed easily and inexpensively.

[0019] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and each of the above-described components can be appropriately modified within the scope of the present invention. In the above embodiment, the case of pile construction has been described, but the use of the method for suppressing the swaying of a suspended load and the system for suppressing the swaying of a suspended load 4 is not limited thereto, and they can be used to suppress the swaying of any suspended load on water, such as crane work in general offshore construction work or the lifting and lowering of cargo. [Explanation of symbols]

[0020] 1. Offshore wind power generation facilities (floating facilities) 2 stakes 3. Crane ship 31 Crane 32 Lifting wire 33 Pile Gripper 4. Load sway suppression system 5. Motion reduction device 51 Electromagnet 52 Weight 53 Device wire 54 Through hole 6 Wave height gauge 7 Calculation method 8 Control Means

Claims

1. A method for suppressing the swaying of a load suspended by a crane of a crane ship, comprising: a wave height measurement step of measuring the wave height and period of waves; a hull oscillation calculation step of calculating a hull oscillation amount, which is an oscillation amount of the crane ship, based on the wave height and the wave period; a load sway calculation step of calculating a load sway amount, which is the amount of sway of the load, based on the ship hull sway amount; a sway reduction step of moving a weight suspended by the crane up and down between the tip of the crane and the suspended load in accordance with the amount of sway of the suspended load.

2. 2. The method for suppressing swings of a suspended load according to claim 1, wherein the step of calculating swings of the suspended load calculates the amount of swings of the suspended load based on the amount of hull swings, the angle of elevation of the boom of the crane, and the horizontal angle of the boom.

3. In the ship motion calculation step, 3. A method for suppressing the swinging of a suspended load according to claim 1, wherein the amount of hull swinging is calculated based on the amount of translational movement of the crane vessel in the vertical direction, the amount of rotation of the crane vessel about the longitudinal axis of the hull, and the amount of rotation of the crane vessel about the minor axis of the hull.

4. 4. A method for suppressing the sway of a suspended load according to claim 1, further comprising the step of calculating a sway reduction force caused by movement of the weight according to the amount of sway of the suspended load based on the mass and acceleration of the weight, the amount of sway of the suspended load, and the mass of the suspended load.

5. A load sway suppression system for suppressing the sway of a load suspended by a crane of a crane ship, a motion reduction device provided between the tip of the crane and the suspended load; a wave height meter for measuring the wave height and period; a calculation means for calculating the amount of oscillation of the suspended load based on the wave height and the wave period; and a control means for controlling the motion reduction device, The motion reduction device includes a pair of electromagnets spaced apart from one another in the vertical direction, and a weight that moves up and down between the pair of electromagnets due to the magnetic force of the electromagnets, The control means controls the electromagnet so that the weight moves up and down in accordance with the amount of sway.

6. a hoisting wire for suspending the load passes through a through-hole formed in the center of the motion reduction device without contacting the wire; 6. The suspended load motion suppression system according to claim 5, wherein the motion suppression device is suspended from the crane by a device hoisting wire.

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