A system and method for moving a floating object on water to a target location.

Abstract

Compared to conventional technologies for automating ship movement, this system enables the floating object to reach its target position with high precision and in a short amount of time. [Solution] The arrival determination unit 111 determines whether or not the floating body B has reached the target position. The difference identification unit 112 identifies the difference between the actual direction of movement and the direction of movement towards the target position from the position at the end of the previous cycle. The target movement direction determination unit 113 takes the identified difference into account and determines the target direction of movement from the current position of the floating body B to the target position at regular intervals. The tension ratio determination unit 114 determines the ideal tension to be applied to each winch 2 so that the maximum and minimum values ​​of the load ratio of the winch 2, which are determined based on the determined target movement direction and the direction of the wire, fall within a predetermined range. The rotational force determination unit 115 determines the rotational force of the winch drum so that the tension of the wires connected to each of the multiple winches becomes the ideal tension.

Description

Technical Field

[0001] The present invention relates to each of a plurality of winches mounted on a floating body on water, and controls the operations of the plurality of winches in an operation of moving the floating body on water from a current position to a target position by adjusting the payout amount of a wire connected to each of the winches and an anchor dropped into water.

Background Art

[0002] Among floating bodies on water such as ships, floats, and floating bridges, there are so-called non-self-propelled types that do not have a propulsion mechanism for navigating themselves. A non-self-propelled floating body on water is moored in a work area by, for example, a plurality of anchors lowered around it. And, for example, a ground improvement work ship such as a deep mixing treatment ship, which is one of the non-self-propelled floating bodies on water, moves by adjusting the payout amount (including the hoisting amount) of a wire connected to those anchors by a winch installed on the hull. This moving operation is generally called "ship rotation".

[0003] By the way, a floating body on water is subjected to the action of many external forces such as wind, waves, tidal currents, water flow from rivers, wake waves caused by the navigation of other ships, and reflected waves from structures such as breakwaters. Since it is difficult to predict the action of these external forces received by the hull, the winch operation for ship rotation depends on an operator with accumulated experience. However, since operators are chronically insufficient and aging is also a problem, a technology for automating the winch operation for ship rotation is required.

[0004] As a patent document including the above description regarding the automation of ship rotation, for example, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] When automating the movement of a floating vessel, it is necessary to determine the rotational force of each drum of multiple winches so that the floating vessel moves from its current position to its target position. Such rotational forces of drums can be calculated using a relatively simple method.

[0007] However, when the drum is rotated using the rotational force calculated as described above to change the amount of wire released, the actual direction in which the floating body moves will not necessarily coincide with the assumed direction due to the influence of waves, wind, wire slack, frictional force between the sheave and the wire that feeds out the wire, and so on.

[0008] In view of the above circumstances, the present invention provides a technology that can reach a floating body on the water to a target position with high precision and in a short time, compared to conventional technologies for automating boat turning. [Means for solving the problem]

[0009] In one embodiment, the present invention provides a system for controlling the operation of a plurality of winches mounted on a floating body in an operation to move the floating body from its current position to a target position by adjusting the amount of wire paid out from each of the winches connected to an anchor dropped into the water, the system comprising: a process of determining a target movement direction which is the direction in which the floating body approaches the target position from its current position; a process of determining the rotational force of each drum of the plurality of winches so that the floating body moves in the target movement direction; and a process of instructing each of the plurality of winches to rotate its drum with the rotational force determined in the process of determining the rotational force, the system repeats this series of processes until the floating body reaches a predetermined distance from the target position. [Effects of the Invention]

[0010] According to the present invention, compared to conventional technologies for automating boat movement, a floating body on the water can be reached to its target position with high precision and in a short amount of time. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram illustrating the overview of ground improvement system 9. [Figure 2] A diagram showing an example of the configuration installed on floating body B. [Figure 3] A diagram showing an example of the configuration of the ground improvement machine 3. [Figure 4] A diagram showing an example of the configuration of ground improvement system 9. [Figure 5] A diagram showing an example of the functional configuration of the control device 1. [Figure 6] A flowchart illustrating an example of the overall operation flow of control device 1. [Figure 7] A diagram illustrating the procedure for determining the target movement direction. [Figure 8] A diagram illustrating the procedure for calculating the winch's load ratio. [Figure 9] A flowchart illustrating an example of the operation flow in which control device 1 determines rotational force. [Figure 10] A diagram showing an example of a damping formula. [Figure 11] A diagram showing examples of each parameter that is calculated. [Figure 12] A diagram showing an example of the configuration of a modified ground improvement system 9. [Figure 13] A diagram showing an example of the functional configuration of a modified ground improvement system 9. [Figure 14] A diagram showing an example of the configuration of a modified ground improvement system 9. [Figure 15] A diagram showing an example of the functional configuration of a modified ground improvement system 9. [Modes for carrying out the invention]

[0012] <Embodiment> <Configuration of the ground improvement system> FIG. 1 is a diagram for explaining the outline of the ground improvement system 9. FIG. 1 depicts a plan view of the floating body B floating on water such as the sea, viewed from above. In this figure, the water surface is approximated as a plane. That is, the coordinates of the water surface are defined in the xy plane coordinates. For example, the x coordinate corresponds to latitude and the y coordinate corresponds to longitude.

[0013] The floating body B shown in FIG. 1 is connected by wires to anchors A1 to A6 (hereinafter referred to as "anchor A" when not distinguishing them) respectively anchored at six points in the mooring area R0. The xy coordinates of the anchor A are fixed and known during construction. By changing the lengths of the six wires respectively, the floating body B can move within the mooring area R0. The construction area R1 is the area to be constructed.

[0014] FIG. 2 is a diagram showing an example of the configuration mounted on the floating body B. As shown in FIG. 2, a fairlead FL, a control device 1, a winch 2, and a ground improvement machine 3 are mounted on the floating body B.

[0015] The winch 2 is a driving device for paying out and winding up the wire, and includes a drum for winding up the wire. By rotationally driving the drum, operations such as winding up the wire are performed. Examples of the driving method of the winch 2 include a hydraulic type, an electric type, an engine type, etc. Six winches 2 are provided on the floating body B shown in FIG. 2.

[0016] The fairlead FL is a device also called a wire guide or a cable guide, which protects the wire and changes its path. Six fairleads FL are provided at six locations on the floating body B shown in FIG. 2. These six fairleads FL are independently opposed to each of the six winches 2 described above, and the wire connecting each winch 2 and the anchor A enters and exits the winch 2 in the direction perpendicular to the drum rotation axis.

[0017] The wires mooring the floating body B extend along the straight line connecting the coordinates of the fair leader FL and anchor A, assuming no deflection due to external forces is considered. Therefore, winch 2 can move the floating body B by adjusting the amount of wires paid out and reeled in. Here, "external forces" refer to forces acting on the ground improvement system 9 from outside, such as wind and waves, and do not include the action and reaction of forces between the components of the ground improvement system 9, such as the floating body B, winch 2, wires, and anchor A.

[0018] Ground improvement machine 3 is a device that improves ground such as the seabed by penetrating it with a rotating and stirring shaft and injecting and stirring ground improvement materials such as cement solidifying agents. Figure 3 is a plan view showing an example of the configuration of ground improvement machine 3. The ground improvement machine 3 shown in Figure 3 has four rotating and stirring shafts that extend vertically, and these rotating and stirring shafts are penetrated into the seabed ground to perform ground improvement. The area improved by the four rotating and stirring shafts is called the construction area 30.

[0019] The floating body B is moved by the winch 2 so that its construction range 30 completely covers the construction area R1. Then, at each point where the floating body B stops, the ground improvement machine 3 performs ground improvement, thereby improving the ground throughout the entire construction area R1.

[0020] The control device 1 is a device that controls the winch 2 so that the construction range 30 completely covers the construction area R1.

[0021] Figure 4 shows an example of the configuration of the ground improvement system 9. As shown in Figure 4, the ground improvement system 9 has, in addition to the configuration shown in Figure 2, a rotation speed / tension meter 4 and a position / orientation sensor 5.

[0022] The rotational speed / tension meter 4 is a measuring instrument that measures the rotational speed of the drum that winds up the wire in the winch 2, as well as the tension applied to the wire. This rotational speed / tension meter 4 may be a single measuring instrument that integrates a rotational speed meter and a tension meter, or it may be a configuration that combines a separate rotational speed meter and a tension meter. Here, a positive value for the drum's rotational speed indicates that it is winding up the wire, and a negative value indicates that it is unwinding the wire.

[0023] The position and direction sensor 5 is a sensor that detects the position and direction of the floating body B. This position and direction sensor 5 measures the position of the floating body B and the direction its bow is pointing, for example, using the Global Navigation Satellite System (GNSS). The position and direction sensor 5 is, for example, a GNSS (Global Navigation Satellite System) compass. Of course, the position and direction sensor 5 is not limited to a GNSS compass and may be composed of a combination of separate sensors that detect position and direction, respectively. In other words, the position and direction sensor 5 described above does not prevent the provision of a direction sensor in addition to the position sensor.

[0024] The control device 1 includes a processor 11, memory 12, and interface 13. The memory 12 includes RAM (Random Access Memory), ROM (Read Only Memory), a solid-state drive, a hard disk drive, etc., and stores computer programs (hereinafter simply referred to as programs).

[0025] The processor 11 controls each part of the control unit 1 by reading and executing a program from the memory 12. The processor 11 is, for example, a CPU (Central Processing Unit).

[0026] Interface 13 is a communication circuit that connects the control device 1 to other devices via wired or wireless means, enabling communication. The control device 1 shown in Figure 4 is connected to the winch 2, ground improvement machine 3, rotation speed / tension meter 4, and position / orientation sensor 5 via interface 13, enabling communication.

[0027] <Functional Configuration of Control Device> Figure 5 shows an example of the functional configuration of the control device 1. The processor 11 of the control device 1 functions as a reach determination unit 111, a difference identification unit 112, a target movement direction determination unit 113, a tension ratio determination unit 114, a rotation force determination unit 115, and a rotation force instruction unit 116 by executing a program stored in the memory 12.

[0028] The arrival determination unit 111 compares the current position information of the floating body B obtained from the position / direction sensor 5 with the target position stored in the memory 12 to determine whether the floating body B has reached the target position by remaining within a predetermined distance range from the target position for a specific period of time. The processor 11 continues a series of processes according to the functional configuration described below until the arrival determination unit 111 determines that the floating body B has reached within a predetermined distance range from the target position. In other words, the processor 11 repeats the series of processes until the floating body B reaches within a predetermined distance range from the target position. The arrival determination unit 111 continues its function even after the arrival determination described above. This allows the floating body B to remain within the predetermined distance range described above.

[0029] The target movement direction determination unit 113 determines the direction in which the floating body B approaches the target position from its current position at regular intervals, and determines this as the "target movement direction." In other words, the process performed by this target movement direction determination unit 113 is an example of the process of determining the target movement direction, which is the direction in which the floating body approaches the target position from its current position.

[0030] The difference identification unit 112 uses the current position and orientation information of the floating body B at the end of the current cycle, obtained from the position and orientation sensor 5, and the position and orientation information of the floating body B at the end of the previous cycle (i.e., the start of the current cycle) stored in the memory 12 to determine the direction in which the floating body B actually moved between the start and end of the current cycle (hereinafter referred to as the "actual movement direction"). The difference identification unit 112 then identifies the difference (hereinafter referred to as the "specific movement difference") between the actual movement direction and the direction of the target position from the position at the end of the previous cycle, i.e., the position at the start of the current cycle, toward the target position.

[0031] The target movement direction determination unit 113 shown in Figure 5 takes a specific movement difference into account when determining the target movement direction. For example, the target movement direction determination unit 113 sets a virtual target point located away from the target position in a direction that cancels out the specific movement difference, and determines the direction from the position of the floating body B on the water at the end of the previous cycle to this virtual target point as the target movement direction. Since the effect of external forces is reflected in the specific movement difference that occurred in the previous cycle, if the effect of those external forces does not change significantly, the floating body B will move towards the virtual target point instead of the target position, so that the specific movement difference and the effect of external forces cancel each other out at the end of the current cycle, and it will move to a position closer to the target position. In this way, the target movement direction determination unit 113 changes the target movement direction each cycle, assuming that the same specific movement difference that occurred in the previous cycle will occur in the current cycle as well.

[0032] Therefore, the ground improvement system 9, which includes a control device 1 as a component having a processor 11 that functions as a difference identification unit 112 and a target movement direction determination unit 113, is an example of a system that includes a process to identify the difference between the direction in which a floating body moves from its current position to the target position and the actual movement direction of the floating body, and determines the target movement direction using the difference identified in the past.

[0033] The tension ratio determination unit 114 first determines the load ratio of each winch 2 based on the target movement direction determined by the target movement direction determination unit 113 and the direction of the wires extending from each fair leader FL. Next, the tension ratio determination unit 114 determines the ideal tension to be applied to each winch 2 so that the maximum and minimum values ​​of the load ratio fall within a predetermined range for equipment maintenance (hereinafter referred to as the "tension range"). The tension range is, for example, from 20 [kN] to 150 [kN].

[0034] Therefore, the above-described process performed by the tension ratio determination unit 114 is an example of a process that determines the ratio of the tensions of each of the multiple wires connected to each of the multiple winches, and a process that determines the tension of each of the multiple wires according to the ratio determined in the process that determines this ratio, and such that the tensions of the multiple wires are within a predetermined range.

[0035] The rotational force determination unit 115 first obtains the actual tension applied to the wire of each winch 2 (hereinafter referred to as "measured tension") from the rotational speed / tension meter 4 that measured it. Then, the rotational force determination unit 115 determines the acceleration / deceleration rotation speed of the drum of each winch 2 (forward rotation (+) is wire winding rotation, and reverse rotation (-) is wire unwinding rotation) according to the difference (hereinafter referred to as "tension difference") between this acquired measured tension and the ideal tension determined by the tension ratio determination unit 114.

[0036] The rotational force determination unit 115 may also determine an adjusted "adjusted acceleration / decrease rotational speed" by uniformly multiplying each of the determined acceleration / decrease rotational speeds by a specific coefficient, such as "0.5". The specific coefficient is not limited to 0.5, but is preferably set to 0.3 or higher and 0.7 or lower. This determination of the adjusted acceleration / decrease rotational speed suppresses overload on the wire caused by sudden changes in rotational speed.

[0037] Furthermore, the method by which the rotational force determination unit 115 determines the adjustment rotation speed is not limited to the method of uniformly multiplying the adjustment rotation speed by the specific coefficient described above. For example, the rotational force determination unit 115 may estimate the trend of the influence of external forces over the most recent multiple periods in the past by an approximate straight line or approximate curve (hereinafter referred to as the "approximation line") based on a correlation analysis between the rotational force instructed to each winch 2 in each of the most recent multiple periods in the past (hereinafter referred to as the "instructed rotation speed") and the amount of change in the measured tension, and then determine the adjustment rotation speed so that it corresponds to the instructed rotation speed in the most recent period in the past (for example, the previous period) based on the estimated approximation line (relationship between the instructed rotation speed and the amount of change in the measured tension). Note that the amount of change in the measured tension in the most recent period in the past is not limited to the previous period, but may be the average amount of change in the measured tension over all multiple periods that formed the basis of the approximation line, or it may be the average amount of change in the measured tension over arbitrarily selected multiple periods. However, in any case, it is preferable to include the amount of change in the measured tension over the previous period.

[0038] Next, the rotational force determination unit 115 obtains the measured rotational speed of the drum of each winch 2 from the rotational speed / tension meter 4 that measured it. Then, the rotational force determination unit 115 adds the aforementioned adjustment rotational speed or adjustment adjustment rotational speed to the measured rotational speed to determine the target rotational speed. As each winch 2 rotates its drum according to the target rotational speed determined by the rotational force determination unit 115, the floating body B moves in the target movement direction determined by the target movement direction determination unit 113.

[0039] The indicated rotational speed determined by the rotational force determination unit 115 is an example of the rotational force required to rotate the drum of the winch 2. The rotational force determined by the rotational force determination unit 115 is not limited to the indicated rotational speed; for example, it may be the voltage ratio or duty cycle of the motor that drives the drum.

[0040] In other words, this process performed by the rotational force determination unit 115 is an example of a process that determines the rotational force of each drum of multiple winches so that the floating body on the water moves in the direction of the target movement.

[0041] Furthermore, as each winch 2 rotates the drum according to the instructed rotation speed determined by the rotational force determination unit 115, the wire connected to the winch 2 approaches the ideal tension described above.

[0042] Therefore, this process performed by the rotational force determination unit 115 is an example of a process that determines the rotational force of the winch drum so that the tension of the wires connected to each of the multiple winches becomes the tension determined in the tension determination process described above (i.e., the ideal tension).

[0043] The rotational force instruction unit 116 transmits the instruction rotational speed determined by the rotational force determination unit 115 to each winch 2, instructing them to rotate the drum at this instruction rotational speed. In other words, the process performed by this rotational force instruction unit 116 is an example of a process that instructs each of the multiple winches to rotate the drum with the rotational force determined in the process of determining the rotational force.

[0044] <Operation of the control device> Figure 6 is a flowchart showing an example of the overall operation flow of the control device 1. The processor 11 of the control device 1 acquires the current position and orientation of the floating body B from the position and orientation sensor 5 at predetermined time intervals (step S101). The processes from step S101 to step S111, which are executed at predetermined time intervals, constitute one cycle.

[0045] The processor 11 then determines whether the floating body B has reached the target location (step S102). More specifically, the processor 11 determines whether the target location has been reached if the distance between the acquired current location and the target location remains within a predetermined range for a specific period of time.

[0046] If it is determined that the floating body B has reached the target position (step S102; YES), the processor 11 terminates the series of processes according to the flow in Figure 6. On the other hand, if it is determined that the floating body B has not reached the target position (step S102; NO), the processor 11 determines whether the current process is the process immediately following the start (i.e., the process corresponding to the first cycle) (step S103). If it is determined that the process is not immediately following the start (step S103; NO), the processor 11 identifies the actual direction of movement in the most recent past cycle (step S104), and determines whether there is a difference between this actual direction of movement and the direction of movement from the position of the floating body B at the start of the cycle toward the target position (step S105).

[0047] If it is determined that there is a difference (step S105; YES), the processor 11 identifies that difference as a specific movement difference and updates the target movement direction based on the specific movement difference (step S106). At this time, the processor 11 determines the new target movement direction, for example, so that it moves in a direction in which the specific movement difference is canceled out.

[0048] If, in step S103, it is determined that the process has just started (step S103; YES), the processor 11 proceeds to step S106 without performing steps S104 and S105 described above. That is, immediately after the start, the processor 11 determines the initial target movement direction. Immediately after the start, there is no actual movement direction from the previous cycle, so the target movement direction is determined by the target position and the current position.

[0049] Figure 7 is a diagram illustrating an example of the procedure for determining the target movement direction. In Figure 7, the position of the floating body B is represented by the position of the ground improvement machine 3. As shown in Figure 7, the floating body B is at position P(i) at a certain point in time, and when a predetermined period (e.g., "0.5 seconds") has elapsed from that point in time, it is at position P(i+1). Note that Figure 7 illustrates a case where there is no difference between the expected arrival position G(i-1), which is one period prior (not shown), and the actual arrival position P(i-1), and the target movement direction during the period in which the floating body B moves from position P(i) is the direction from position P(i) to the target position G(n).

[0050] As described above, the target direction of movement for the floating body B in the period from position P(i) is towards the target position G(n). However, there is a difference Δ(i+1) between the position G(i+1) that should have been reached at the end of the period if it had moved in this target direction, and the position P(i+1) that was actually reached.

[0051] In the example shown in Figure 7, the processor 11 sets position G(n)b1, which is obtained by adding the opposite vector of the vector indicated by this difference to the target position G(n), as a virtual target point during the period in which the floating body B moves from position P(i+1). Then, it updates the direction from the current position P(i+1) toward the virtual target point G(n)b1 as the new target movement direction.

[0052] It should be noted that the virtual target point mentioned above does not change the target position G(n) itself, but rather is a target that takes into account the influence of external forces indicating the direction in which the floating body B approaches the target position, and is updated at the predetermined cycles mentioned above. For example, in the example shown in Figure 7, at the end of the cycle in which the floating body B moves from position P(i) to position P(i+1), that is, at the start of the next cycle, the processor 11 assumes that a difference equivalent to the difference Δ(i+1) mentioned above occurs in that cycle, and sets position G(i+2) as the expected destination position on the line connecting position P(i+1) and the target position G(n). However, the actual destination position is P(i+2) due to the influence of changes in external forces. At the end of the cycle from P(i+1) to P(i+2), the processor 11 sets a new virtual target point, G(n)b2, which is the position obtained by adding the opposite vector of the difference Δ(i+2) between the predicted destination position G(i+2) and the actual destination position P(i+2) to the target position G(n), and updates the direction from the current position P(i+2) to this position G(n)b2 as the new target movement direction.

[0053] When step S106 shown in Figure 6 is completed, the processor 11 proceeds to step S107. Also, if it is determined in step S105 shown in Figure 6 that there is no difference between the actual direction of movement and the direction of the target position, the processor 11 also proceeds to step S107.

[0054] In step S107, the processor 11 calculates the load ratio of each winch 2 (step S107). At this time, the processor 11 calculates the load ratio of each winch 2 such that the vector based on the target movement direction determined in step S106 is created by combining vectors along the pulling direction of each winch 2.

[0055] Figure 8 is a diagram illustrating an example of calculating the load ratio of the winches. As shown in Figure 8, the floating body B has six winches 2 (not shown in Figure 8) and a fair leader FL corresponding to each of the winches 2. The floating body B is moored by wires that extend from each winch 2, are reoriented at the fair leader FL they pass through, and then extend toward the corresponding anchors A.

[0056] The processor 11 assigns unknown coefficients (α1 to α6) to each of the vectors (hereinafter referred to as "wire-along vectors") along the wires that are fed out or wound up by the six winches 2 and extend from the six corresponding fair leader FLs to anchor A. The processor 11 then calculates the coefficients (α1 to α6) such that the sum of the results obtained by multiplying each coefficient by a wire-along vector (v1 to v6) of a predetermined length (e.g., unit length) matches a vector of a predetermined length (L) along the target movement direction. The processor 11 uses the calculated coefficients (α1 to α6) as the load ratio for each winch 2.

[0057] The coefficients (α1 to α6) mentioned above can be calculated by selecting two or more wires from the six wires and averaging the coefficients obtained from all possible combinations of selections. For example, if two wires are selected from the six wires, there are 15 possible combinations. The processor 11 then tries all 15 calculations and uses the average of the coefficients for each wire obtained in each calculation as the load ratio for each winch 2.

[0058] Note that the number of winches 2 installed on the floating body B is not limited to six. Also, if the processor 11 finds that there are more than a specified number of linearly dependent vectors, i.e., pairs of parallel vectors, among the selected vectors, it may exclude one of those pairs from the calculation.

[0059] As described above, once the load ratio of winch 2 is calculated, the processor 11 then reads and determines a predetermined tension range to be applied to the wire based on safety conditions determined by the durability performance of the wire and winch 2 (step S108). The tension range to be applied to the wire is set in advance by the manager, manufacturer, etc., of the floating body B. Then, the processor 11 adjusts the load ratio of each winch 2 to fall within this tension range and determines the tension ratio applied to the wire (step S109). This tension ratio is used to determine the ideal tension to be applied to the wire of each winch 2.

[0060] Once the tension ratio is determined as described above, the processor 11 then obtains the rotational speed of the drum of each winch 2 and the tension applied to the wire, measured in the current cycle, from the rotational speed / tension meter 4 (step S110). Based on the obtained rotational speed and tension, the processor 11 then determines the rotational force to be instructed to each winch 2 in the next cycle (step S200).

[0061] Figure 9 is a flowchart showing an example of the operation flow in which the control device 1 determines the rotational force. The processor 11 reads and references the damping formula from the memory 12 (step S201). Then, based on this damping formula, the processor 11 determines the upper limit of the rotational speed of the winch 2 drum (hereinafter referred to as the "upper limit of rotational speed") according to the remaining distance from the current position to the target position (hereinafter referred to as the "remaining distance") (step S202).

[0062] Figure 10 is a graph illustrating an example of a damping formula. The damping formula shown in the example graph in Figure 10 represents the relationship between the remaining distance and the upper limit of the rotational speed. The damping formula is expressed as a monotonically increasing function with the remaining distance as the independent variable. That is, the shorter the remaining distance, the lower the upper limit of the rotational speed. This is a limitation because, as the floating body B on the water approaches the target position, it is necessary to reduce the rotational speed of the winch 2's drum to ensure braking force.

[0063] For example, the damping equation shown by the solid line graph in Figure 10 can be expressed by the function shown in equation (1) below.

[0064] [Mathematics 1] Upper limit of rotations = (Maximum upper limit - Minimum upper limit) × tanh(remaining distance) + Minimum upper limit ... (1)

[0065] Here, the maximum upper limit is the rotational speed limit when the remaining distance is longest in the defined domain. The minimum upper limit is the rotational speed limit when the remaining distance is shortest in the defined domain. Calculations according to equation (1) show that the rotational speed limit gradually decreases as the remaining distance decreases, and the rate of decrease becomes steeper as the remaining distance approaches zero.

[0066] Note that the damping formula is not limited to that expressed by equation (1) above. For example, the damping formula shown by the dashed line graph in Figure 10 is a linear function. That is, according to this damping formula, the amount of change in the upper limit of rotational speed when the remaining distance changes is proportional to the amount of change in the remaining distance.

[0067] The processor 11 calculates the remaining distance from the current position of the floating body B obtained from the position and orientation sensor 5, and determines the upper limit of rotational speed corresponding to this calculated remaining distance by referring to the damping formula described above. For example, if the damping formula expressed by equation (1) described above is adopted, as shown in Figure 10, if the remaining distance is 1.3 [m], the upper limit of rotational speed will be 272 [rpm].

[0068] The rotational speed limit determined by referring to the damping formula described above is the upper limit of the speed that decreases as the distance between the current position of the floating body B and the target position decreases. Therefore, the processes in steps S201 and S202 are examples of processes for determining the upper limit of the speed that decreases as the distance between the current position of the floating body B and the target position decreases.

[0069] Following the process of determining the upper limit of the rotational speed described above (step S202 in Figure 9), the processor 11 calculates the tension difference for each winch 2, which is the difference between the ideal tension determined according to the tension ratio determined in step S109 in Figure 6 and the measured tension obtained in step S110 in Figure 6, and identifies the winch 2 that shows the largest tension difference (hereinafter referred to as "maximum tension difference").

[0070] Then, the processor 11 assigns the upper limit of rotational speed determined in step S202 to the winch 2 that showed the maximum tension difference (step S203), and determines the acceleration / decrease rotational speed of each winch 2 so that the zero point of the tension difference coincides with the zero point of the acceleration / decrease rotational speed (or adjusted acceleration / decrease rotational speed; the same applies hereinafter) (step S204).

[0071] Once the acceleration and deceleration speeds are determined, the processor 11 adds the acceleration and deceleration speeds to the rotational speed of the drum of each winch 2 obtained in step S110 (i.e., the measured rotational speed) to determine the instruction rotational speed to be given to each winch 2 (step S205).

[0072] In other words, the processor 11 assigns the upper limit of rotational speed, determined by referring to the damping formula, to the winch 2 with the maximum tension difference, and determines the acceleration / decrease rotational speed of each winch 2 so that the wire payout or winding speed in this winch 2 is less than or equal to the aforementioned upper limit of rotational speed.

[0073] Therefore, this ground improvement system 9 is an example of a system that determines the speed of each wire being deployed or hoisted up so that it is less than or equal to an upper limit of rotational speed determined such that it decreases as the distance between the current position and the target position of the floating body on the water decreases.

[0074] Figure 11 shows examples of parameters calculated by processor 11. In the example shown in Figure 11, the load ratio of winch 2 is smallest for winch 2 with winch ID "W5" and largest for winch 2 with winch ID "W3". When the tension range from 20 [kN] to 150 [kN] is applied to these, six ideal tensions can be determined.

[0075] Furthermore, the tension difference for each winch 2 is determined by measuring the actual tension and calculating the difference from the ideal tension. In the example shown in Figure 11, the maximum tension difference was shown for winch 2 with winch ID "W3", so the rotational speed limit of 272 [rpm] is assigned to this winch 2.

[0076] Then, by multiplying the ratio of the tension difference of each winch to the maximum tension difference by the upper limit of the rotational speed, the amount of acceleration / decrease rotation to be added to each winch 2 is determined. This amount of acceleration / decrease rotation, or an adjusted amount of acceleration / decrease rotation obtained by multiplying this amount of acceleration / decrease rotation by a predetermined coefficient, is added to the measured rotational speed to determine the indicated rotational speed. In the example shown in Figure 11, the indicated rotational speed is calculated by adding an adjusted amount of acceleration / decrease rotation obtained by multiplying the actual rotational speed by a coefficient of 0.5. Alternatively, the amount of acceleration / decrease rotation or the adjusted amount of acceleration / decrease rotation itself may be determined as the indicated rotational speed.

[0077] As shown in Figure 9, once the rotational force instruction value is determined in step S200, the processor 11 transmits this determined rotational force instruction value to each winch 2 to instruct them to rotate (step S111), as shown in Figure 6, and returns to step S101. In other words, the processor 11 repeats the series of processes from step S101 to step S111 until the floating body B reaches the target position. When step S111 is completed, the processor 11 waits for a predetermined period (for example, 0.5 seconds) to elapse from the time when step S101 of that period was executed, before resuming the processing of step S101 of the next period.

[0078] As explained above, the ground improvement system 9 according to this embodiment corrects and updates the target movement direction to eliminate the difference between the actual movement direction and the target position direction caused by the received external force at relatively short intervals. Therefore, compared to conventional technologies for automating ship movement, the floating body on the water can reach the target position with high precision and in a short time.

[0079] <Variation> The above describes the embodiment, but the contents of this embodiment can be modified as follows. Furthermore, the following modifications may be combined.

[0080] <1> In the embodiment described above, the target movement direction determination unit 113 changed the target movement direction based on the assumption that the same specific movement difference that occurred one cycle earlier had occurred. However, the method for determining the target movement direction from the specific movement difference is not limited to this. For example, the target movement direction determination unit 113 may determine the target movement direction from the specific movement difference using a machine learning model that has been trained using pre-prepared training data.

[0081] Figure 12 shows an example of the configuration of a ground improvement system 9 according to this modified example. In the ground improvement system 9 shown in Figure 12, the control device 1 stores a direction learning model 121 in memory 12. This direction learning model 121 is a model that has been pre-machine-trained using training data that associates multiple explanatory variables related to the floating body B or a similar object (hereinafter referred to as "floating body B, etc.") with the direction of movement of the floating body B, etc. as the objective variable. Here, the explanatory variables related to the floating body B, etc. include, for example, the current position of the floating body B, etc., the positions of multiple anchors A, the difference between the actual direction of movement and the direction of the target position identified in the past (specific movement difference), and the actual direction of movement. Furthermore, the explanatory variables related to the floating body B, etc. may also include observation results such as meteorological and oceanographic conditions.

[0082] Figure 13 shows an example of the functional configuration of the modified ground improvement system 9. In the ground improvement system 9 shown in Figure 13, the target movement direction determination unit 113, which is implemented by the processor 11 of the control device 1, receives explanatory variables from the direction learning model 121 stored in the memory 12. These variables include the current position of the floating body B detected by the position / orientation sensor 5, the positions of multiple anchors A previously stored in the memory 12, the specific movement difference identified in the past (the difference between the target position direction and the actual movement direction), and the movement direction from the current position toward the target position (target position direction). The target movement direction determination unit 113 then determines the target movement direction output by the direction learning model 121 in response to the input of these explanatory variables as the target movement direction for the next cycle.

[0083] In other words, the ground improvement system 9 in this modified example is an example of a system in which a machine learning model, which has been trained using training data that includes the current position, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the actual direction of movement as explanatory variables for a floating body or a similar object on a water, and the target direction of movement as the dependent variable, is input with explanatory variables that include the current position, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the direction of movement from the current position toward the target position for a floating body on a water, and the target direction of movement output by the learning model in response to the input of said explanatory variables is determined as the target direction of movement for the floating body on a water.

[0084] Furthermore, in this modified example, the method for generating the direction learning model 121 using a computer or other computing device is an example of a method that includes the step of performing machine learning on a learning model using training data in which the current position, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the actual direction of movement are included as explanatory variables for a floating body on water, and the target direction of movement is included as the dependent variable.

[0085] <2> In the embodiment described above, the rotational force determination unit 115 acquires the measured tension of the wire of each winch 2, determines the adjustment rotation speed (or adjustment adjustment rotation speed; the same applies hereinafter) of the drum of each winch 2 according to the tension difference between the measured tension and the ideal tension, and determines the target rotation speed by adding this adjustment rotation speed to the acquired measured rotation speed. Alternatively, the rotational force determination unit 115 may determine the target rotation speed from factors other than the measured tension. For example, the rotational force determination unit 115 may determine the target rotation speed based on the difference between the actual movement direction and the target position direction, i.e., the specified movement difference, which is identified by the difference identification unit 112.

[0086] In other words, the ground improvement system 9, which includes a processor 11 that functions as a rotational force determination unit 115, is an example of a system that determines the rotational force of each of several winches based on the differences identified in the process of identifying differences performed in the past, in the process of determining the rotational force of the drum.

[0087] <3> Variations described above <2> In this context, various methods can be considered for the rotational force determination unit 115 to determine the instructed rotational speed based on a specific movement difference. For example, the rotational force determination unit 115 may determine the instructed rotational speed from the specific movement difference using a machine learning model that has been trained using pre-prepared training data.

[0088] Figure 14 shows an example of the configuration of the ground improvement system 9 according to this modified example. In the ground improvement system 9 shown in Figure 14, the control device 1 stores a rotational force learning model 122 in the memory 12. This rotational force learning model 122 is a model that has been pre-trained using training data that associates multiple explanatory variables related to the floating body B with the rotational force of each of the multiple winches 2 used to move the floating body B on the water as the objective variable.

[0089] Here, the rotational force, which is the objective variable, may be the indicated rotational speed of each winch 2, as in the embodiment described above, or it may be the rotational force indicated by other parameters. Furthermore, the explanatory variables for the floating body B, etc., include, for example, the current position of the floating body B, the positions of the multiple anchors A, the difference between the actual direction of movement and the direction of the target position (specific movement difference) identified in the past, and the direction of the target position. In addition, the explanatory variables for the floating body B, etc., may include observational results such as meteorological and oceanographic conditions.

[0090] Figure 15 shows an example of the functional configuration of the ground improvement system 9 according to this modified example. In the ground improvement system 9 shown in Figure 15, the rotational force determination unit 115, which is implemented by the processor 11 of the control device 1, inputs explanatory variables to the rotational force learning model 122 stored in the memory 12, including the current position of the floating body B on the water detected by the position and orientation sensor 5, the positions of each of the multiple anchors A that are previously stored in the memory 12, a specific movement difference identified in the past, and the direction of the target position. Then, the rotational force determination unit 115 determines the rotational force (for example, the instructed rotation speed) of each winch 2 output by the rotational force learning model 122 in response to the input of these explanatory variables, as the rotational force of each winch 2 in the next cycle. The rotational force instruction unit 116 transmits the rotational force determined by the rotational force determination unit 115 to each winch 2 and instructs it to rotate the drum.

[0091] In other words, the ground improvement system 9 in this modified example is an example of a system in which, in the process of determining rotational force, the current position of a floating body or a similar object on a water surface, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the target position direction are included as explanatory variables, and the rotational force of each of the multiple winches is included as the objective variable. The system inputs explanatory variables, including the current position of the floating body, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the target position direction, to a learning model that has been machine-trained using training data. The system then determines the rotational force of each of the multiple winches output by the learning model in response to the input of these explanatory variables as the rotational force of each of the multiple winches on the floating body.

[0092] Furthermore, in this modified example, the method for generating the rotational force learning model 122 using a computer or other computing device is an example of a method that includes the step of performing machine learning on a learning model using training data in which the current position, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the target position direction are included as explanatory variables for a floating body on water, and the rotational force of each of the multiple winches is included as the objective variable.

[0093] <4> In the embodiment described above, the rotational force determination unit 115 determines the rotational force of the winch 2 drum so that the tension of the wire connected to each of the winches 2 becomes the ideal tension. However, the method for determining this rotational force is not limited to this. For example, the rotational force determination unit 115 obtains the rotational speed of the drum that actually feeds out or winds up the wire in each winch 2 from the rotational speed / tension meter 4 that measures it. The rotational force determination unit 115 then obtains the load ratio of each winch 2 determined by the tension ratio determination unit 114, determines the ideal ratio of the rotational speed of the drum of each winch 2 (hereinafter referred to as the "ideal rotational speed ratio") from this load ratio, and determines the instructed rotational speed to each winch 2 so that the actual rotational speed of the drum is within a predetermined range according to this ideal rotational speed ratio.

[0094] In this case, the process by which the rotational force determination unit 115 determines the rotational force of the drum is an example of a process that includes: determining the ratio of the unwinding or winding speeds of each of the multiple wires connected to the multiple winches; determining the unwinding or winding speed of each of the multiple wires according to the ratio determined in the process of determining the ratio, and such that the unwinding or winding speeds of the multiple wires are within a predetermined range; and determining the rotational force of the drum so as to unwind or wind up the wires connected to each of the multiple winches at the determined speeds.

[0095] <5> In the modified example described above, the rotational force determination unit 115 may determine the rotational force, such as the indicated rotational speed of the drum, in accordance with the limitations on the tension of the wire. For example, the rotational force determination unit 115 may adjust the indicated rotational speed, which has been determined according to the ideal rotational speed ratio so that the actual rotational speed of the drum is within a predetermined range, so that the tension on the wire is within a predetermined range when the drum is rotated according to that indicated rotational speed.

[0096] In this case, the process by which the rotational force determination unit 115 determines the rotational force of the drum is an example of a process that includes adjusting the rotational force of the drum so that the tension of the multiple wires falls within a predetermined range when the drums of the multiple winches rotate to the determined speed for unwinding or winding the multiple wires.

[0097] <6> In the embodiment described above, the tension ratio determination unit 114 calculated the load ratio for each winch so that the vector based on the target movement direction is created by combining vectors along the direction of traction by each winch 2. However, the load ratio for each winch may be corrected based on the relationship between the change in the measured wire tension and the indicated rotational speed of the drum over several recent past cycles. For example, the tension ratio determination unit 114 derives an approximate relationship between the indicated rotational speed and the change in the measured wire tension for each of the 10 most recent past cycles for each winch 2. From the approximate relationship thus derived, the tension ratio determination unit 114 calculates the change in wire tension corresponding to the indicated rotational speed to be given to each winch 2 in the next cycle as the estimated change in tension. The tension ratio determination unit 114 assigns the lower limit of an arbitrarily set correction coefficient range to the winch 2 with the largest difference between the estimated tension change calculated in this way and the most recent measured tension change in the past, and assigns the upper limit of the correction coefficient range to the winch 2 with the smallest difference. The tension ratio determination unit 114 then assigns correction coefficients to the other winches 2 that correspond to the relative ratio of the difference between the estimated tension change and the most recent measured tension change in the past among the winches 2. The tension ratio determination unit 114 then corrects the load ratio of each winch 2 by multiplying the load ratio of each winch 2 by the correction coefficients assigned to each winch 2 in this way.

[0098] The approximate relationship between the indicated rotational speed used to correct the load ratio of winch 2 as described above and the change in the measured tension of the wire is calculated by the processor 11 from the measured tension of the wire and the indicated rotational speed of the drum, which are stored in memory 12. The past indicated rotational speed and measured tension of the wire used by the processor 11 to calculate the approximate relationship are not limited to those of the most recent 10 cycles, but the number of cycles may be changed depending on, for example, the weather conditions when turning the floating vessel B. [Explanation of Symbols]

[0099] 1...Control device, 11...Processor, 111...Reach determination unit, 112...Difference identification unit, 113...Target movement direction determination unit, 114...Tension ratio determination unit, 115...Rotation force determination unit, 116...Rotation force instruction unit, 12...Memory, 121...Direction learning model, 122...Rotation force learning model, 13...Interface, 2...Winch, 3...Ground improvement machine, 30...Construction area, 4...Tension meter, 5...Direction sensor, 9...Ground improvement system, A1~A6...Anchor, R0...Mooring area, R1...Construction area

Claims

1. A system for controlling the operation of a plurality of winches mounted on a floating body on water in the operation of moving the floating body from its current position to a target position by adjusting the amount of wire paid out by each of the winches connected to an anchor dropped into the water, A process to determine the target movement direction, which is the direction in which the floating body approaches the target position from its current position on the water, A process to determine the rotational force of each drum of the plurality of winches so that the floating body on the water moves in the direction of the target movement, A process to instruct each of the plurality of winches to rotate the drum with the rotational force determined in the process of determining the rotational force, The series of processes including the above are repeated until the floating body reaches a predetermined distance from the target position. system.

2. The series of processes described above includes a process to identify the difference between the direction of the target position, which is the direction from the current position of the floating body toward the target position, and the actual direction of movement of the floating body. In the process of determining the target movement direction, the difference identified in the process of identifying the difference performed in the past is used to determine the target movement direction. The system according to claim 1.

3. In the process of determining the target direction of movement, a machine learning model, which has been trained using training data in which the current position, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the actual direction of movement are included as explanatory variables for the floating body or a similar object of the floating body, and the target direction of movement is included as the dependent variable, is input with explanatory variables including the current position, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the direction of movement from the current position toward the target position for the floating body, and the target direction of movement output by the learning model in response to the input of said explanatory variables is determined as the target direction of movement for the floating body. The system according to claim 2.

4. The series of processes described above includes a process to identify the difference between the direction of the target position, which is the direction from the current position of the floating body toward the target position, and the actual direction of movement of the floating body. In the process of determining the rotational force of the drum, the rotational force of each of the multiple winches is determined based on the differences identified in the process of identifying differences that were performed in the past. The system according to claim 1.

5. In the process of determining the rotational force, a machine learning model, which has been trained using training data that includes the current position, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the target position direction as explanatory variables for the floating body or a similar object of the floating body, and the rotational force of each of the multiple winches as an objective variable, is input with explanatory variables including the current position, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the target position direction for the floating body, and the rotational force of each of the multiple winches output by the learning model in response to the input of said explanatory variables is determined as the rotational force of each of the multiple winches for the floating body. The system according to claim 4.

6. The process for determining the rotational force of the drum includes: determining the ratio of the tensions of each of the multiple wires connected to the multiple winches; determining the tension of each of the multiple wires according to the ratio determined in the ratio determination process, and such that the tensions of the multiple wires are within a predetermined range; and determining the rotational force of the drum such that the tension of the wires connected to each of the multiple winches is the tension determined in the tension determination process. The system according to claim 1.

7. The process for determining the rotational force of the drum includes: determining the ratio of the unwinding or winding speeds of each of the multiple wires connected to the multiple winches; determining the unwinding or winding speed of each of the multiple wires according to the ratio determined in the ratio determination process, and such that the unwinding or winding speeds of the multiple wires are within a predetermined range; and determining the rotational force of the drum such that the unwinding or winding speed of the wires connected to each of the multiple winches is the speed determined in the speed determination process. The system according to claim 1.

8. The process for determining the rotational force of the drum includes a process for adjusting the rotational force determined in the process for determining the rotational force of the drum so that the tension of the multiple wires is within a predetermined range when the drums of the multiple winches rotate so that the speed of unwinding or winding the multiple wires is the speed determined in the process for determining the speed. The system according to claim 7.

9. The process for determining the rotational force of the drum includes a process for determining an upper limit of the speed that decreases as the distance between the current position of the floating body on the water and the target position decreases. In the process of determining the speed, the speed of each of the multiple wires being unfurled or hoisted is determined such that the unfurling or hoisting speed of each of the multiple wires is less than or equal to the upper limit determined in the process of determining the upper limit. The system according to claim 7.

10. A method for generating a learning model used by the system described in claim 3, This step involves performing machine learning on a learning model using training data that includes the current position of a floating object on water, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the actual direction of movement as explanatory variables, and the target direction of movement as the dependent variable. A method for providing this.

11. A method for generating a learning model used by the system described in claim 5, This step involves performing machine learning on a learning model using training data that includes the current position of a floating object on water, the positions of multiple anchors, the difference between the previously identified target position direction and the actual direction of movement, and the target direction of movement as explanatory variables, and the rotational force of each of the multiple winches as the dependent variable. A method for providing this.

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