Anchoring decision-making method and system for anchoring combined dynamic positioning system

Abstract

The invention relates to the technical field of ship motion control, and particularly discloses an anchoring decision-making method and system for an anchoring combined dynamic positioning system, and the method comprises the following steps: S1, obtaining a target position, a target heading and environment measurement information which need to be maintained when a ship hovers, and calculating an environment interference load to be borne by the ship; s2, thrust distribution is carried out with the minimum energy consumption and abrasion of a propeller as the target according to the environment interference load, and the optimal acting force of the anchor cable is obtained through calculation; and S3, according to the optimal acting force of the anchor cable, an optimal anchoring scheme is obtained through calculation. According to the method, a combination scheme of the optimal anchoring position and the anchor cable length can be calculated by taking the lowest energy consumption and abrasion of the thruster as standards according to the current sea wind wave flow environment, the ship body hydrodynamic characteristics, the thruster thrust and the installation position on the premise that the ship can meet the positioning precision requirement, and long-term operation of the ship at an operation point is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of ship motion control, and particularly to an anchor throwing decision method and system for an anchor mooring combined with a dynamic positioning system. Background Art

[0002] For ocean platforms and special ships to carry out long-term offshore operations, they need to have the functions of maintaining position and heading under the interference of wind, waves and currents. At present, the widely adopted ship positioning methods mainly include two types: a dynamic positioning system and an anchor mooring positioning system. Whether the two systems operate independently or the existing joint operation schemes have the following technical defects: 1. Low energy consumption efficiency: When the dynamic positioning system resists the interference of the wind, wave and current environment, it needs to continuously consume a large amount of energy. Especially under strong interference conditions, the thrusters work at a high load for a long time, and the fuel cost surges.

[0003] 2. Non-optimal anchor mooring configuration: The existing anchor mooring positions mostly rely on the ship handling experience or a simplified calculation model, and do not fully consider the coupling relationship between the energy consumption characteristics of the dynamic positioning system and the anchor mooring force, resulting in the potential of the anchor mooring system not being fully exploited during joint operation.

[0004] 3. Limited calculation dimension: The existing technologies usually use manual experience or single-objective optimization for the anchor mooring selection of a multi-anchor system, the coordination of the anchor throwing position and the cable length, and it is difficult to accurately handle the non-linear optimization calculation problem under multi-anchor, combined dynamic positioning system and multi-constraint conditions. Summary of the Invention

[0005] The present invention aims to solve the above problems. To this end, the present invention provides an anchor throwing decision method and system for an anchor mooring combined with a dynamic positioning system. First, evaluate the environmental interference that needs to be overcome to maintain the desired position and attitude in the operation sea area; by regarding each anchor cable of the anchor mooring system as a "virtual thruster", the virtual thruster and the real thruster jointly participate in the thrust distribution of the dynamic positioning system, but only with the low energy consumption and low wear of the real thruster as the evaluation target, and thus calculate the optimal tension of the anchor mooring system that makes the dynamic positioning system the most energy-efficient and has the lightest wear; then further inversely calculate the corresponding anchor throwing position and the cable length of the anchor cable.

[0006] The present invention can, according to the current sea wind, wave and current environment, the hull hydrodynamic characteristics, the thruster thrust and the installation position, on the premise that the ship can meet the positioning accuracy requirements, calculate the combination scheme of the best anchor throwing position and the cable length of the anchor cable with the lowest energy consumption and wear of the thruster as the standard, which is beneficial for the ship to carry out long-term operations at the operation point.

[0007] The present invention provides an anchor throwing decision method for an anchor mooring combined with a dynamic positioning system, and the adopted technical solution is as follows: including the following steps: S1: Obtain the target position, target heading, and environmental measurement information that the ship needs to maintain when hovering, and calculate the environmental interference load that the ship will be subjected to; S2: According to the environmental disturbance load, with the goal of minimizing the energy consumption and wear of the thruster, the thrust is distributed and the optimal force of the anchor cable is calculated; S3: Calculate the best anchoring solution based on the optimal force of the anchor cable.

[0008] Furthermore, the environmental disturbance loads include longitudinal, transverse and bow wind loads, wave loads and flow loads.

[0009] Furthermore, the calculation formula for wind load is: in, The current wind direction in the operating sea area; is the target heading of the ship; is the relative wind direction angle of the ship; is the longitudinal wind load on the ship, is the lateral wind load on the ship, is the bow wind load on the ship; is the dimensionless wind load coefficient of the hull longitudinal direction, is the dimensionless wind load coefficient of the hull transverse direction, is the dimensionless wind load coefficient of the bow direction of the hull; is the current wind speed in the operating sea area; is the air density, is the windward projected area of the hull, is the side wind projected area of the hull, is the overall length of the hull; The calculation formula for wave load is: in, The current wave direction in the operating sea area; is the relative wave direction angle of the ship; is the longitudinal wave load on the ship, is the transverse wave load on the ship, is the bow wave load on the ship; is the dimensionless second-order wave load coefficient in the longitudinal direction of the hull, is the dimensionless second-order wave load coefficient of the hull transverse direction, is the dimensionless second-order wave force load coefficient at the bow of the ship; is the current significant wave height in the operating sea area, is the current wave period in the operating sea area; is the density of seawater, is the length between perpendiculars of the ship; The calculation formula for the current load is: Among them, is the current flow direction in the operation sea area; is the relative flow angle of the ship affected by the current; is the longitudinal current load on the ship, is the transverse current load on the ship, is the bow current load on the ship; is the longitudinal non-dimensional current load coefficient of the hull, is the transverse non-dimensional current load coefficient of the hull, is the bow non-dimensional current load coefficient of the hull; is the current velocity in the operation sea area; is the ship width, is the draft; The calculation formula for the environmental interference load is: Among them, is the longitudinal environmental interference load on the ship, is the transverse environmental interference load on the ship, is the bow environmental interference load on the ship.

[0010] Furthermore, in S2, each anchor cable is regarded as a virtual thruster that can generate a force, and all thrusters and all anchor cables jointly generate a control force acting on the ship, and boundary constraint conditions are constructed; Without considering the anchor cables and only considering the thrusters, an evaluation function is constructed with the goal of minimizing the energy consumption and wear of the thrusters; According to the boundary constraint conditions and the evaluation function, thrust allocation is performed to calculate the optimal force of the anchor cables.

[0011] Furthermore, the boundary constraint conditions are as follows: Among them, is the control force requirement for ship dynamic positioning, used to resist the environmental interference load, is the thruster thrust vector, is the thruster azimuth angle vector, is the transformation matrix for converting the thrust of all thrusters into the hull coordinate system; is the anchor cable tension vector, is the anchor cable azimuth angle vector, is the transformation matrix for converting the tension of all anchor cables into the hull coordinate system, is the distribution error between the control force requirement and the actual control force; is the maximum thrust limit of all thrusters, is the thrust vector of all thrusters at the previous moment, is the thrust change limit within one control cycle of all thrusters, is the lower boundary of the thrust azimuth angle of all thrusters, is the upper boundary of the thrust azimuth angle of all thrusters, is the thrust azimuth angle vector of all thrusters at the previous moment, is the thrust angle range change limit within one control cycle of all thrusters, is the maximum tension limit of the anchor cable, is the lower boundary of the anchor cable tension azimuth angle, is the upper boundary of the anchor cable tension azimuth angle.

[0012] Furthermore, the evaluation function is: where, is the thrust of the i-th thruster, T represents the transpose matrix, is the accuracy penalty coefficient of thrust allocation, is the energy consumption penalty coefficient of thrust allocation, is the wear penalty coefficient of thrust allocation.

[0013] Furthermore, the optimal acting force of the anchor cable is the anchor cable tension and the anchor cable azimuth angle. In S3, according to the anchor cable tension and the anchor cable azimuth angle, an iterative method is used to calculate the best combination of the anchor point position and the anchor cable length, and the best anchoring plan is obtained.

[0014] Furthermore, the specific process of calculating the best anchoring plan is as follows: S3.1: Select a point on the ray starting from the anchor hole of the anchor cable and in the direction of the anchor cable azimuth angle, and use the seabed position corresponding to this point as the assumed anchor point; S3.2: Calculate the horizontal distance between the anchor hole and the assumed anchor point; S3.3: According to the horizontal distance and the anchor cable tension, use the catenary theory to calculate the anchor cable length; S3.4: Judge whether the anchor cable length meets the actual conditions; If it meets the actual conditions, the current assumed anchor point and the anchor cable length are the best anchoring plan for this anchor cable; If it does not meet the actual conditions, move the position of this point on the ray, re-determine the assumed anchor point, and enter S3.2.

[0015] Further, points are selected from the ray in the order from near to far from the ship. The initial position of the points is 2 times the water depth, and the interval value of each movement of the points is taken as 0.1 times the water depth.

[0016] The present invention also provides an anchor - dropping decision - making system for an anchor - mooring combined dynamic positioning system, and the adopted technical solution is as follows: It includes: a data acquisition module, an anchor cable force calculation module, and an anchor - dropping plan calculation module. The data acquisition module is used to obtain the target position and target heading that the ship needs to maintain during hovering, as well as environmental measurement information, and calculate the environmental disturbance load that the ship will be subjected to. The anchor cable force calculation module is used to perform thrust distribution with the lowest energy consumption and wear of the thrusters as the goal according to the environmental disturbance load, and calculate the optimal force of the anchor cable. The anchor - dropping plan calculation module is used to calculate the best anchor - dropping plan according to the optimal force of the anchor cable.

[0017] One or more of the above - mentioned technical solutions in the embodiments of the present invention have at least one of the following technical effects: 1. Fully exploit the potential of the anchor - mooring system and significantly reduce the energy consumption of the dynamic positioning system: By regarding the anchor - mooring system as a "virtual thruster" and incorporating it into the dynamic positioning thrust distribution, and taking the lowest energy consumption and wear of the real thrusters as the evaluation, the present invention obtains the optimal force of the anchor cable, giving full play to the potential of the anchor - mooring system.

[0018] 2. The configuration parameters are scientific and accurate: After calculating the optimal force of the anchor cable of the anchor - mooring system, the present invention uses reverse derivation to calculate the best combination of the corresponding anchor - dropping point position and anchor cable length, breaking through the limitations of the traditional anchor - dropping empirical method and being more scientific and accurate.

[0019] 3. Compatible with multi - dimensional calculations and constraints: The present invention fully considers factors such as the constraints of the multi - anchor system, the multi - dimensional combination of the anchor - dropping point position and cable length of the anchor cable, and the multi - dimensional calculations and constraints of the thrusters, and has a wide range of applicable scenarios.

[0020] 4. Full - life - cycle benefits: By reducing the power consumption and wear of the thrusters, the present invention effectively reduces the use load, extends the service life of the key components of the dynamic positioning system, reduces carbon emissions, and conforms to the development trend of green ship technology.

[0021] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is the flowchart of the method provided by the present invention.

[0024] Figure 2 It is a schematic diagram of the feasible region of the anchor cable tension during the thrust distribution calculation provided by the present invention.

[0025] Figure 3 It is a schematic diagram of the iterative calculation of the optimal anchor point of the anchor cable provided by the present invention.

[0026] Figure 4 It is a schematic diagram of the relative position and underwater attitude of the anchor cable provided by the present invention.

[0027] Figure 5 It is a block diagram of the system structure provided by the present invention.

[0028] Reference numerals: 1. Data acquisition module; 2. Anchor cable force calculation module; 3. Anchoring plan calculation module. Specific embodiments

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0030] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without conflict, those skilled in the art can combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0031] Combine the following Figures 1 to 5 The present invention is further described in detail, and an anchoring decision method and system of an anchoring combined dynamic positioning system of the present invention are described: In this embodiment, Figure 1 As shown, a method for dropping anchor of an anchoring combined with a dynamic positioning system is provided, comprising the following steps: S1: Obtain the target position, target heading, and environmental measurement information that the ship needs to maintain when hovering, and calculate the environmental interference load that the ship will be subjected to at the target position and target heading in combination with the current environmental measurement information.

[0032] The operator determines the target position and heading that the ship needs to maintain when hovering during offshore operations based on the task requirements. Environmental measurement information is collected through environmental sensors.

[0033] Generally, environmental interference loads include three items, namely wind load, wave load and flow load. When calculating, the three loads need to be divided into components in three directions, including longitudinal, transverse and bow directions. The specific calculation process of environmental interference loads is as follows: Wind loads include longitudinal, transverse and bow wind loads on the ship, and the calculation formula is: in, The current wind direction in the operating sea area is measured by environmental sensors; The target heading of the ship, which is set by the operator in combination with the operation task; is the relative wind direction angle of the ship; is the longitudinal wind load on the ship, is the lateral wind load on the ship, is the bow wind load on the ship; is the dimensionless wind load coefficient of the hull longitudinal direction, is the dimensionless wind load coefficient of the hull transverse direction, is the dimensionless wind load coefficient of the bow, , and It can be obtained through CFD numerical simulation or wind tunnel test; The current wind speed in the operating sea area is measured by environmental sensors; is the air density, is the windward projected area of the hull, is the side wind projected area of the hull, is the total length of the hull, all of which are constants or known parameters.

[0034] Wave loads include longitudinal, transverse and bow wave loads on the ship, and the calculation formula is: Among them, is the current wave direction of the operation sea area, which is measured by the environmental sensor; is the relative wave direction angle of the ship affected by the wave; is the longitudinal wave load on the ship, is the transverse wave load on the ship, is the bow wave load on the ship; is the longitudinal non-dimensional second-order wave force load coefficient of the hull, is the transverse non-dimensional second-order wave force load coefficient of the hull, is the bow non-dimensional second-order wave force load coefficient of the hull, which can be obtained through hydrodynamic simulation; is the significant wave height of the current operation sea area, is the wave period of the current operation sea area, , which are measured by the environmental sensor; is the sea water density, is the length between perpendiculars of the ship, both of which are constants or known parameters.

[0035] The current load includes the longitudinal, transverse, and bow current loads on the ship, and the calculation formula is: Among them, is the current flow direction of the operation sea area, which is measured by the environmental sensor; is the relative flow direction angle of the ship affected by the current; is the longitudinal current load on the ship, is the transverse current load on the ship, is the bow current load on the ship; is the longitudinal non-dimensional current load coefficient of the hull, is the transverse non-dimensional current load coefficient of the hull, is the bow non-dimensional current load coefficient of the hull, which can be obtained in advance through CFD numerical simulation or wind tunnel test; is the current velocity of the operation sea area, which is measured by the environmental sensor; is the ship width, is the draft, both of which are known parameters.

[0036] The calculation formula of the environmental interference load is: Among them, is the longitudinal environmental interference load on the ship, is the transverse environmental interference load on the ship, is the bow environmental interference load on the ship.

[0037] S2: According to the environmental interference load, with the goal of minimizing the energy consumption and wear of the thrusters, perform thrust allocation and calculate the optimal acting force of the anchor cables.

[0038] The thrust allocation calculation is an optimization calculation process. The boundary constraints of the thrusters, the boundary constraints of the anchor cable forces, and the optimization evaluation index adopt the following scheme: Based on the actual situation, clarify the thrust extreme value constraints, thrust change constraints, thrust angle constraints, and thrust angle change constraints of all thrusters. Consider each anchor cable as a virtual thruster that can generate an acting force, and clarify the tensile extreme value constraints and tensile angle constraints of all anchor cables according to the actual situation. The combined action of all thrusters and all anchor cables generates the control force acting on the ship, and the boundary constraint conditions are as follows: Among them, is the control force requirement for ship dynamic positioning, used to resist the environmental interference load generated by wind, waves, and currents. , is the thruster thrust vector. , is the thrust of the first thruster. is the total number of thrusters. is the thruster azimuth angle vector. , is the azimuth angle of the first thruster. is the transformation matrix for converting the thrust of all thrusters to the hull coordinate system. , is the actual longitudinal installation position of the first thruster relative to the ship center. is the actual transverse installation position of the first thruster relative to the ship center; is the anchor cable tensile force vector. , is the tensile force of the first anchor cable. is the total number of anchor cables participating in the combined dynamic positioning control of mooring. is the anchor cable azimuth angle vector. , The azimuth angle of the first anchor cable. is the transformation matrix for converting the tensile force of all anchor cables to the hull coordinate system. , is the actual longitudinal installation position of the first virtual thruster relative to the ship center. The actual transverse installation position of the first virtual thruster relative to the ship center, and its value is the longitudinal position and transverse position of the anchor hole of this anchor cable relative to the ship center; is the allocation error between the control force requirement and the actual control force. is the control force acting on the ship generated by all thrusters; is the control force acting on the ship generated by all anchor cables; is the maximum thrust limit of all thrusters, is the thrust vector of all thrusters at the previous moment, is the limit of thrust change of all thrusters within one control cycle, is the lower boundary of the thrust azimuth angle of all thrusters, is the upper boundary of the thrust azimuth angle of all thrusters, is the thrust azimuth angle vector of all thrusters at the previous moment, is the limit of thrust angle range change of all thrusters within one control cycle, is the maximum tension limit of the anchor cables, is the lower boundary of the anchor cable tension azimuth angle, is the upper boundary of the anchor cable tension azimuth angle. Generally, the anchor cable tension azimuth angle boundary is set as a fan-shaped boundary of ±60° with the vertical hull direction as the symmetry axis and outside the hull. Figure 2 is the schematic diagram of the feasible region of the anchor cable tension in the thrust distribution calculation, Figure 2 shows the anchor cable tension azimuth angle boundary (±60°) of two anchor cables on the left side of the ship, and the maximum tension limit of the anchor cables (the maximum tension limit of the No. 1 anchor cable and the maximum tension limit of the No. 2 anchor cable ).

[0039] In this embodiment, an optimization evaluation index is designed, which comprehensively considers the satisfaction of the control force requirement (characterized by accuracy), the total power of all real thrusters (excluding "virtual thrusters") (characterized by energy consumption), and the azimuth angle change rate of all real thrusters (excluding "virtual thrusters") (characterized by mechanical wear). Without considering the anchor cables and only considering the thrusters, an evaluation function is constructed with the goal of minimizing the energy consumption and wear of the thrusters is: where, is the thrust of the i-th thruster, T represents the transpose matrix, is the accuracy penalty coefficient of thrust distribution, is the energy consumption penalty coefficient of thrust distribution, is the wear penalty coefficient of thrust distribution, , , are user-settable -dimensional, -dimensional, -dimensional diagonal matrices, and the larger their values, the more the user emphasizes this item.

[0040] Select the optimization method to perform the thrust allocation calculation: For the optimization problem consisting of boundary constraints and evaluation functions, methods such as sequential quadratic programming, interior point method, particle swarm algorithm, etc. can be used to find the optimal forces of all thrusters and all anchor cables. The specific calculation process will not be elaborated here. The optimal forces of all anchor cables are the tensile force magnitudes and directions of each anchor cable.

[0041] In this embodiment, only thrusters are considered in the evaluation function, and virtual thrusters (anchor cables) are not considered. When solving using boundary constraints, both thrusters and anchor cables are involved.

[0042] S3: Calculate the optimal anchoring plan based on the optimal forces of the anchor cables.

[0043] The optimal anchoring plan in this step is the best combination of the anchoring point position and the anchor cable length. According to the anchor cable tension and the anchor cable azimuth angle calculated in step S2, the best combination of the anchoring point position and the anchor cable length is calculated by an iterative method.

[0044] For all anchor cables, calculate the best combination of the anchoring point position and the anchor cable length for each anchor cable respectively. The best anchoring point position of any anchor cable is on the ray starting from its anchor hole and in the direction of the optimal anchor cable azimuth angle; in the order from near to far from the ship, with the minimum value being 2 times the water depth and the interval value being 0.1 times the water depth, an iterative calculation method is used to find the best anchoring point position of this anchor cable. The specific process is as follows: S3.1: Select a point on the ray starting from the anchor hole of the anchor cable and in the direction of the anchor cable azimuth angle, and use the seabed position corresponding to this point as the assumed anchoring point.

[0045] S3.2: Calculate the horizontal distance between the anchor hole and the assumed anchoring point based on the target position, target heading of the ship for the operation task, the position of the anchor hole relative to the ship center, and the assumed anchoring point: where, is the northward position of the target position of the ship for the operation task represented in the north - east coordinate system, is the eastward position of the target position of the ship for the operation task represented in the north - east coordinate system, is the target heading of the ship, is the longitudinal offset of the anchor hole of the th anchor cable relative to the ship center, is the lateral offset of the anchor hole of the th anchor cable relative to the ship center, is the The northward position of the anchor hole of the the eastward position of the anchor hole of the the northward position of the assumed anchor point of the the eastward position of the assumed anchor point of the the horizontal distance of the

[0046] S3.3: According to the horizontal distance and the anchor cable tension, using the catenary theory, calculate the anchor cable length: wherein, the anchor cable length of the is the unit wet weight of the mooring cable, which is a known quantity for the anchor cable of known material, is the tension of the j-th anchor cable, and sinh() is the hyperbolic sine function.

[0047] S3.4: Judge whether the anchor cable length meets the actual conditions: wherein, is the vertical height difference between the anchor hole and the assumed anchor point, which can be measured by a water depth sensor; the maximum anchor cable length of the

[0048] If it meets the actual conditions, the current assumed anchor point and the anchor cable length are the optimal anchoring scheme for this anchor cable; If it does not meet the actual conditions, move the position of this point on the ray, re-determine the assumed anchor point, and enter S3.2.

[0049] Select points from the ray in the order from near to far from the ship. The initial position of the point is 2 times the water depth, and the interval value of each movement of the point is taken as 0.1 times the water depth. Adopt the iterative calculation method to continuously adjust the position of the assumed anchor point until the corresponding anchor cable length meets the actual conditions, and obtain a reasonable and feasible anchoring scheme.

[0050] Figure 3 is the schematic diagram of the iterative calculation of the optimal anchor point of the anchor cable, Figure 3 shows the iterative selection process of the assumed anchor point of the No. 1 anchor cable. The azimuth of the arrow in the figure is the azimuth angle of the anchor cable (ray direction). The distance between the initial position of the selected point and the anchor hole is 2 times the draft. A total of 8 assumed anchor points are selected along the ray direction. For the anchor point, the relative position and the attitude in the water of the anchor cable are asFigure 4 as shown

[0051] This embodiment also provides an anchoring decision-making system for an anchor mooring combined with a dynamic positioning system, as Figure 5 shown, and the technical solution adopted is as follows: It includes: a data acquisition module 1, an anchor cable force calculation module 2, and an anchoring plan calculation module 3.

[0052] The data acquisition module is used to obtain the target position and target heading that the ship needs to maintain when hovering, as well as environmental measurement information, and calculate the environmental disturbance load that the ship will be subjected to. The environmental disturbance load includes wind load, wave load, and current load in the longitudinal, lateral, and heading directions.

[0053] The anchor cable force calculation module is used to perform thrust distribution with the lowest energy consumption and wear of the thrusters as the goal according to the environmental disturbance load, and calculate the optimal force of the anchor cable. Only the thrusters are considered in the evaluation function, and the virtual thrusters (anchor cables) are not considered. When solving using the boundary constraint conditions, both the thrusters and the anchor cables are involved. The optimal force of the anchor cable is the anchor cable tension and the anchor cable azimuth angle.

[0054] The anchoring plan calculation module is used to calculate the best anchoring plan according to the optimal force of the anchor cable. According to the anchor cable tension and the anchor cable azimuth angle, an iterative method is used to calculate the best combination of the anchoring point position and the anchor cable length to obtain the best anchoring plan.

[0055] The applicable object of the present invention is a ship equipped with a dynamic positioning function, which is applicable to both single-anchor and multi-anchor systems. The applicable scenario is the auxiliary decision-making of the anchoring plan before the ship conducts anchor mooring combined positioning operations. The present invention can provide intelligent anchoring decision-making support in advance for offshore engineering ships to carry out anchor mooring combined with dynamic positioning control in a complex operating environment, and has obvious and irreplaceable important engineering practice value different from other methods in the application field of the anchor mooring combined with dynamic positioning system.

[0056] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An anchor - throwing decision - making method for an anchor - mooring combined dynamic positioning system, characterized in that, It includes the following steps: S1: Obtain the target position, target heading that the ship needs to maintain during hovering, and environmental measurement information, and calculate the environmental interference load that the ship will be subjected to; S2: Based on the environmental interference load, with the goal of minimizing the energy consumption and wear of the thrusters, perform thrust allocation and calculate the optimal force of the anchor cable; In S2, each anchor cable is regarded as a virtual thruster that can generate a force. All thrusters and all anchor cables jointly generate a control force acting on the ship, and boundary constraint conditions are constructed; Only consider the thrusters and construct an evaluation function with the goal of minimizing the energy consumption and wear of the thrusters; Based on the boundary constraint conditions and the evaluation function, perform thrust allocation and calculate the optimal force of the anchor cable; S3: Calculate the optimal anchoring plan based on the optimal force of the anchor cable.

2. The anchor - dropping decision - making method for an anchor - mooring combined dynamic positioning system according to claim 1, characterized in that, The environmental interference load includes wind load, wave load, and current load in the longitudinal, lateral, and heading directions.

3. The anchor - dropping decision - making method of an anchor - mooring combined dynamic positioning system according to claim 2, characterized in that, The calculation formula for the wind load is: in, The current wind direction in the operating sea area; is the target heading of the ship; is the relative wind direction angle of the ship; is the longitudinal wind load on the ship, is the lateral wind load on the ship, is the bow wind load on the ship; is the dimensionless wind load coefficient of the hull longitudinal direction, is the dimensionless wind load coefficient of the hull transverse direction, is the dimensionless wind load coefficient of the bow direction of the hull; is the current wind speed in the operating sea area; is the air density, is the windward projected area of the hull, is the side wind projected area of the hull, is the overall length of the hull; The calculation formula for the wave load is: wherein, is the current wave direction in the operation sea area; is the relative wave direction angle of the ship affected by the wave; is the longitudinal wave load on the ship, is the transverse wave load on the ship, is the bow wave load on the ship; is the longitudinal non-dimensional second-order wave force load coefficient of the hull, is the transverse non-dimensional second-order wave force load coefficient of the hull, is the bow non-dimensional second-order wave force load coefficient of the hull; is the significant wave height in the operation sea area currently, is the wave period in the operation sea area currently; is the seawater density, is the length between perpendiculars of the ship; The calculation formula for the current load is: wherein, is the current flow direction of the operation sea area; is the relative flow direction angle of the ship affected by the flow; is the longitudinal flow load on the ship, is the lateral flow load on the ship, is the bow flow load on the ship; is the non-dimensional longitudinal flow load coefficient of the hull, is the non-dimensional lateral flow load coefficient of the hull, is the non-dimensional bow flow load coefficient of the hull; is the current flow velocity of the operation sea area; is the ship width, is the draft; The calculation formula for the environmental interference load is: Among them, is the longitudinal environmental interference load acting on the ship, is the lateral environmental interference load acting on the ship, is the heading environmental interference load acting on the ship.

4. The anchor - dropping decision - making method of an anchor - mooring combined dynamic positioning system according to claim 1, wherein The boundary constraint conditions are as follows: Among them, is the control force requirement for ship dynamic positioning, which is used to resist environmental interference loads, is the thruster thrust vector, is the thruster azimuth angle vector, is the transformation matrix for converting the thrust of all thrusters into the hull coordinate system; is the anchor cable tension vector, is the anchor cable azimuth angle vector, is the transformation matrix for converting the tension of all anchor cables into the hull coordinate system, is the distribution error between the control force requirement and the actual control force; is the maximum thrust limit of all thrusters, is the thrust vector of all thrusters at the previous moment, is the thrust change limit within one control cycle of all thrusters, is the lower boundary of the thrust azimuth angle of all thrusters, is the upper boundary of the thrust azimuth angle of all thrusters, is the thrust azimuth angle vector of all thrusters at the previous moment, is the thrust angle range change limit within one control cycle of all thrusters, is the maximum tension limit of the anchor cable, is the lower boundary of the anchor cable tension azimuth angle, is the upper boundary of the anchor cable tension azimuth angle.

5. The anchor - dropping decision - making method of an anchor - mooring combined dynamic positioning system according to claim 4, characterized in that, Evaluation function is as follows: Among them, is the thrust of the i-th thruster, T represents the transpose matrix, is the accuracy penalty coefficient of thrust allocation, is the energy consumption penalty coefficient of thrust allocation, is the wear penalty coefficient of thrust allocation.

6. The anchor dropping decision-making method of an anchor mooring combined dynamic positioning system according to claim 1, wherein The optimal force of the anchor cable is the anchor cable tension and the anchor cable azimuth angle, In S3, based on the anchor cable tension and the anchor cable azimuth angle, use an iterative method to calculate the best combination of the anchoring point position and the anchor cable length to obtain the optimal anchoring plan.

7. The anchor - dropping decision - making method of an anchor - mooring combined dynamic positioning system according to claim 6, characterized in that, The specific process of calculating the optimal anchoring plan is: S3.1: Select a point on the ray starting from the anchor hole of the anchor cable and in the direction of the anchor cable azimuth angle, and use the seabed position corresponding to this point as the assumed anchoring point; S3.2: Calculate the horizontal distance between the anchor hole and the assumed anchoring point; S3.3: Based on the horizontal distance and the anchor cable tension, use the catenary theory to calculate the anchor cable length; S3.4: Determine whether the anchor cable length meets the actual conditions; If it meets the actual conditions, the current assumed anchoring point and the anchor cable length are the optimal anchoring plan for this anchor cable; If it does not meet the actual conditions, move the position of this point on the ray, re-determine the assumed anchoring point, and enter S3.

2.

8. The anchor - dropping decision - making method of an anchor - mooring combined dynamic positioning system according to claim 7, characterized in that, Select points on the ray in the order from near to far from the ship. The initial position of the point is 2 times the water depth, and the interval value of each movement of the point is taken as 0.1 times the water depth.

9. An anchor dropping decision-making system for an anchor mooring combined dynamic positioning system, characterized in that A method for making an anchoring decision for an anchor mooring combined dynamic positioning system according to any one of claims 1 to 8, including: a data acquisition module, an anchor cable force calculation module, and an anchoring plan calculation module, The data acquisition module is used to obtain the target position, target heading that the ship needs to maintain during hovering, and environmental measurement information, and calculate the environmental interference load that the ship will be subjected to; The anchor cable force calculation module is used to perform thrust allocation based on the environmental interference load with the goal of minimizing the energy consumption and wear of the thrusters, and calculate the optimal force of the anchor cable; The anchoring plan calculation module is used to calculate the optimal anchoring plan based on the optimal force of the anchor cable.

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