Anchoring decision method and system for an anchoring combined dynamic positioning system

Abstract

The present invention relates to the technical field of ship motion control, and specifically discloses a method and system for making an anchoring decision for an anchoring combined with a dynamic positioning system. The method comprises the following steps: S1: obtaining a target position, a target heading, and environmental measurement information that the ship needs to maintain when hovering, and calculating the environmental interference load to which the ship will be subjected; S2: based on the environmental interference load, with the goal of minimizing propeller energy consumption and wear, performing thrust distribution, and calculating the optimal force of the anchor cable; S3: calculating the optimal anchoring scheme based on the optimal force of the anchor cable. The present invention can calculate a combination of the optimal anchoring position and anchor cable length based on the current offshore wind, wave, and current environment, the hydrodynamic characteristics of the hull, the thrust of the propeller, and the installation position, on the premise that the ship can meet the positioning accuracy requirements, with the propeller energy consumption and wear being the minimum standard, thereby facilitating the ship to carry out long-term operations at the operating point.

Description

Technical Field

[0001] The present invention relates to the technical field of ship motion control, and in particular to an anchoring decision method and system for an anchoring combined with dynamic positioning system. Background Art

[0002] To conduct long-term offshore operations, offshore platforms and specialized vessels must be able to maintain their position and heading despite wind, wave, and current interference. Currently, the two most widely used ship positioning methods are dynamic positioning systems and anchor positioning systems. Whether these systems operate independently or in combination, existing solutions suffer from the following technical drawbacks:

[0003] 1. Low energy efficiency: The dynamic positioning system consumes a large amount of energy to combat the interference of wind, waves and currents. In particular, under strong interference conditions, the thrusters operate at high loads for a long time, which leads to a surge in fuel costs.

[0004] 2. Non-optimal mooring configuration: Existing mooring positions often rely on ship handling experience or simplified calculation models, without fully considering the coupling relationship between the energy consumption characteristics of the dynamic positioning system and the mooring force. As a result, the potential of the mooring system during combined operations is not fully tapped.

[0005] 3. Computational Dimension Limitations: Existing technologies typically rely on manual experience or single-objective optimization to determine anchor selection and coordinate anchoring positions and cable lengths for multi-anchor systems. This makes it difficult to accurately handle nonlinear optimization calculations for multiple anchors, combined dynamic positioning systems, and under multiple constraints. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned problems. To this end, the present invention provides an anchoring decision method and system for an anchoring combined with dynamic positioning system. First, the environmental interference that needs to be overcome to maintain the desired position and attitude in the operating sea area is evaluated; by treating each anchor cable of the anchoring 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 taking the low energy consumption and low wear of the real thruster as the evaluation target, thereby calculating the optimal tension of the anchoring system that makes the dynamic positioning system most energy-efficient and lightest in wear; and then further reversely calculating the corresponding anchoring position and anchor cable length.

[0007] The present invention can calculate the optimal combination of anchoring position and anchor cable length based on the current offshore wind, wave and current environment, the hydrodynamic characteristics of the hull, the thrust of the propeller and the installation position, on the premise that the ship can meet the positioning accuracy requirements, with the propeller energy consumption and minimum wear as the standards, which is conducive to the long-term operation of the ship at the operation point.

[0008] The present invention provides an anchoring decision method for an anchoring combined with dynamic positioning system, which adopts the following technical solution: comprising the following steps:

[0009] 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;

[0010] S2: Based on the environmental interference load, the thrust is distributed with the goal of minimizing the energy consumption and wear of the thruster, and the optimal force acting on the anchor cable is calculated;

[0011] S3: Calculate the best anchoring solution based on the optimal force of the anchor cable.

[0012] Furthermore, the environmental disturbance loads include longitudinal, transverse and bow wind loads, wave loads and flow loads.

[0013] Furthermore, the calculation formula for wind load is:

[0014]

[0015] 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 transverse wind load on the ship, is the bow wind load on the ship; is the dimensionless wind load coefficient in the longitudinal direction of the hull, is the dimensionless wind load coefficient of the hull transverse direction, is the dimensionless wind load coefficient of the bow; 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;

[0016] The calculation formula for wave load is:

[0017]

[0018] 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 load coefficient of the bow; 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;

[0019] The calculation formula for flow load is:

[0020]

[0021] in, The current direction of the operating sea area; is the relative flow angle of the ship; is the longitudinal flow load on the ship, is the transverse flow load on the ship, is the bow flow load on the ship; is the dimensionless flow load coefficient in the longitudinal direction of the hull, is the dimensionless flow load coefficient in the transverse direction of the hull, is the dimensionless flow load coefficient of the bow direction of the hull; is the current flow velocity in the operating sea area; For the width of the ship, For draft;

[0022] The calculation formula of environmental interference load is:

[0023]

[0024] in, is the longitudinal environmental disturbance load on the ship, is the lateral environmental disturbance load on the ship, is the bow environmental disturbance load on the ship.

[0025] Furthermore, in S2, each anchor cable is regarded as a virtual thruster that can generate force, and all thrusters and all anchor cables jointly generate control force acting on the ship to construct boundary constraints;

[0026] Without considering the anchor cable, only the thruster is considered, and the evaluation function is constructed with the goal of minimizing the energy consumption and wear of the thruster;

[0027] According to the boundary constraints and evaluation function, the thrust is distributed and the optimal force of the anchor cable is calculated.

[0028] Furthermore, the boundary constraints are as follows:

[0029]

[0030] in, To meet the control force requirements for ship dynamic positioning and to resist environmental interference loads. is the thrust vector of the propeller, is the thruster azimuth vector, The transformation matrix for converting all propeller thrust into the hull coordinate system; is the anchor cable tension vector, is the anchor cable azimuth vector, is the transformation matrix for converting all anchor cable tension into the ship coordinate system, It is the distribution error between the control force requirement and the actual control force;

[0031] The maximum thrust limit of all thrusters, is the thrust vector of all thrusters at the previous moment, is the thrust variation limit of all thrusters within one control cycle, is the lower boundary of all thruster thrust azimuths, is the upper limit of all thruster thrust azimuths, is the thrust azimuth vector of all thrusters at the previous moment, is the thrust angle range change limit of all thrusters within one control cycle, The maximum tension limit of the anchor cable is is the lower boundary of the anchor cable tension azimuth, It is the upper boundary of the anchor cable tension azimuth.

[0032] Furthermore, the evaluation function for:

[0033]

[0034] in, is the thrust of the i-th thruster, T represents the transposed matrix, is the accuracy penalty coefficient for thrust distribution, is the energy consumption penalty coefficient for thrust distribution, The wear penalty factor assigned to thrust.

[0035] Furthermore, the optimal forces acting on the anchor cable are the anchor cable tension and the anchor cable azimuth.

[0036] In S3, the optimal combination of anchor point position and anchor cable length is calculated iteratively according to the anchor cable tension and anchor cable azimuth, and the optimal anchoring scheme is obtained.

[0037] Furthermore, the specific process of calculating the optimal anchoring solution is as follows:

[0038] S3.1: Select a point on the ray starting from the anchor hole of the anchor cable and oriented at the anchor cable azimuth, and use the corresponding seabed position as the assumed anchoring point;

[0039] S3.2: Calculate the horizontal distance between the anchor hole and the assumed anchor point;

[0040] S3.3: Calculate the length of the anchor cable using the catenary theory based on the horizontal distance and anchor cable tension.

[0041] S3.4: Determine whether the anchor cable length meets the actual conditions;

[0042] If the actual conditions are met, the current assumed anchoring point and anchor cable length are the optimal anchoring plan for the anchor cable;

[0043] If it does not meet the actual conditions, the position of the point is moved on the ray, the assumed anchor point is re-determined, and the process proceeds to S3.2.

[0044] Furthermore, points are selected from the ray in 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 0.1 times the water depth.

[0045] The present invention also provides an anchoring decision system for an anchoring combined dynamic positioning system, which adopts the following technical solutions: comprising: a data acquisition module, an anchor cable force calculation module and an anchoring plan calculation module,

[0046] 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 interference load that the ship will be subjected to;

[0047] The anchor cable force calculation module is used to distribute thrust according to the environmental interference load and to minimize the energy consumption and wear of the thruster, and to calculate the optimal force of the anchor cable;

[0048] The anchoring scheme calculation module is used to calculate the best anchoring scheme according to the optimal force of the anchor cable.

[0049] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0050] 1. Fully tap the potential of the mooring system and significantly reduce the energy consumption of the dynamic positioning system: This invention treats the mooring system as a "virtual thruster" and incorporates it into the dynamic positioning thrust distribution. It evaluates it based on the energy consumption and wear of the real thruster, obtains the optimal force of the anchor cable, and fully taps the potential of the mooring system.

[0051] 2. Scientific and accurate configuration parameters: After calculating the optimal force of the anchor cable of the mooring system, the present invention uses reverse deduction to calculate the corresponding optimal combination of anchor point position and anchor cable length, breaking through the limitations of traditional anchoring empirical methods and being more scientific and accurate.

[0052] 3. Compatible with multi-dimensional calculations and constraints: This invention fully considers factors such as multi-anchor system constraints, the multi-dimensional combination of anchor point locations and cable lengths, and the multi-dimensional calculations and constraints of thrusters, and is applicable to a wide range of scenarios.

[0053] 4. Benefits throughout the entire life cycle: This invention reduces propeller power consumption and wear, effectively lowers operating load, extends the service life of key components of the dynamic positioning system, and reduces carbon emissions, in line with the development trend of green ship technology.

[0054] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0056] Figure 1 It is a flow chart of the method provided by the present invention.

[0057] Figure 2 It is a schematic diagram of the feasible region of the anchor cable tension provided by the present invention when calculating the thrust distribution.

[0058] Figure 3 This is a schematic diagram of the iterative calculation of the optimal anchoring point for the anchor cable provided by the present invention.

[0059] Figure 4 It is a schematic diagram of the relative position and underwater posture of the anchor cable provided by the present invention.

[0060] Figure 5 This is a system structure diagram provided by the present invention.

[0061] Reference numerals:

[0062] 1. Data acquisition module; 2. Anchor cable force calculation module; 3. Anchoring plan calculation module. DETAILED DESCRIPTION

[0063] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0064] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0065] The following combination 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:

[0066] In this embodiment, Figure 1 As shown, a method for dropping anchor in an anchoring combined with a dynamic positioning system is provided, comprising the following steps:

[0067] S1: Obtain the target position, target heading, and environmental measurement information that the ship needs to maintain when hovering. Combined with the current environmental measurement information, calculate the environmental interference load that the ship will be subjected to at the target position and target heading.

[0068] Based on the operational requirements, the operator determines the target position and heading that the vessel must maintain while hovering during offshore operations. Environmental measurement information is collected through environmental sensors.

[0069] Generally, environmental interference loads include three items: wind load, wave load and flow load. When calculating, the three loads need to be divided into three directional components, including longitudinal, transverse and bow directions. The specific calculation process of environmental interference loads is as follows:

[0070] Wind loads include longitudinal, transverse and bow wind loads on the ship, and the calculation formula is:

[0071]

[0072] in, The current wind direction in the operating sea area is measured by environmental sensors; The target heading of the ship, 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 transverse wind load on the ship, is the bow wind load on the ship; is the dimensionless wind load coefficient in the longitudinal direction of the hull, 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, which are all constants or known parameters.

[0073] Wave loads include longitudinal, transverse and bow wave loads on the ship, and the calculation formula is:

[0074]

[0075] in, The current wave direction in the operating sea area is measured by environmental sensors; 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 load coefficient of the bow, which can be obtained through hydrodynamic simulation; is the current significant wave height in the operating sea area, is the current wave period in the operating sea area, 、 Measured by environmental sensors; is the density of seawater, is the length between perpendicular lines of the ship, which are all constants or known parameters.

[0076] Flow loads include the longitudinal, transverse and bow flow loads on the ship, and the calculation formula is:

[0077]

[0078] in, The current direction of the operating sea area is measured by environmental sensors; is the relative flow angle of the ship; is the longitudinal flow load on the ship, is the transverse flow load on the ship, is the bow flow load on the ship; is the dimensionless flow load coefficient in the longitudinal direction of the hull, is the dimensionless flow load coefficient in the transverse direction of the hull, is the dimensionless flow load coefficient of the bow direction of the hull, which can be obtained in advance through CFD numerical simulation or wind tunnel test; The current flow velocity in the operating sea area is measured by environmental sensors; For the width of the ship, is the draft, all are known parameters.

[0079] The calculation formula of environmental interference load is:

[0080]

[0081] in, is the longitudinal environmental disturbance load on the ship, is the lateral environmental disturbance load on the ship, is the bow environmental disturbance load on the ship.

[0082] S2: Based on the environmental interference load and with the goal of minimizing the energy consumption and wear of the thruster, the thrust is distributed and the optimal force acting on the anchor cable is calculated.

[0083] The thrust distribution calculation is an optimization calculation process. The boundary constraints of the thruster and the anchor cable force, as well as the optimization evaluation index, are as follows:

[0084] Based on the actual situation, the thrust limit constraints, thrust variation constraints, thrust angle constraints, and thrust angle variation constraints of all thrusters are defined. Each anchor cable is considered as a virtual thruster that can generate force, and the tension limit constraints and tension angle constraints of all anchor cables are defined based on the actual situation. All thrusters and all anchor cables jointly generate the control force acting on the ship. The boundary constraints are as follows:

[0085]

[0086] in, To meet the control force requirements for ship dynamic positioning and to resist the environmental interference loads caused by wind, waves and currents. , is the thrust vector of the propeller, , is the thrust of the first thruster, is the total number of thrusters, is the thruster azimuth vector, , is the azimuth angle of the first thruster, is the transformation matrix for converting all propeller thrust into the hull coordinate system, , is the actual longitudinal installation position of the first thruster relative to the center of the ship, is the actual transverse installation position of the first thruster relative to the center of the ship;

[0087] is the anchor cable tension vector, , is the tension of the first anchor cable, is the total number of anchor cables involved in the combined dynamic positioning control of mooring, is the anchor cable azimuth vector, , Azimuth of the first anchor cable, is the transformation matrix for converting all anchor cable tension into the ship coordinate system, , is the actual longitudinal installation position of the first virtual thruster relative to the center of the ship, The actual transverse installation position of the first virtual thruster relative to the center of the ship, whose value is the longitudinal position and transverse position of the anchor hole of the anchor cable relative to the center of the ship;

[0088] It is the distribution error between the control force requirement and the actual control force; The control force acting on the ship generated by all thrusters; The control force exerted on the ship by all anchor cables;

[0089] The maximum thrust limit of all thrusters, is the thrust vector of all thrusters at the previous moment, is the thrust variation limit of all thrusters within one control cycle, is the lower boundary of all thruster thrust azimuths, is the upper limit of all thruster thrust azimuths, is the thrust azimuth vector of all thrusters at the previous moment, is the thrust angle range change limit of all thrusters within one control cycle, The maximum tension limit of the anchor cable is is the lower boundary of the anchor cable tension azimuth, The upper boundary of the anchor cable tension azimuth angle is generally set as a sector boundary with an angle of ±60° on the outside of the hull and with the vertical hull direction as the symmetry axis. Figure 2 This is a schematic diagram of the feasible region of the anchor cable tension in the thrust distribution calculation. Figure 2 The figure shows the anchor cable tension azimuth limit (±60°) of the two anchor cables on the left side of the ship, as well as the maximum tension limit of the anchor cables (maximum tension limit of anchor cable No. 1). and the maximum tension limit of No. 2 anchor cable ).

[0090] This embodiment designs an optimal evaluation index, which comprehensively considers the satisfaction of control force requirements (accuracy), the total power of all real thrusters (excluding "virtual thrusters") (energy consumption), and the azimuth angle change rate of all real thrusters (excluding "virtual thrusters") (mechanical wear). Without considering the anchor cable, only the thrusters are considered, with the goal of minimizing the energy consumption and wear of the thrusters. The evaluation function constructed is for:

[0091]

[0092] in, is the thrust of the i-th thruster, T represents the transposed matrix, is the accuracy penalty coefficient for thrust distribution, is the energy consumption penalty coefficient for thrust distribution, The wear penalty factor assigned to the thrust, 、 、 Is user-settable dimension, dimension, The larger the value, the more important the user is to this item.

[0093] Select an optimization method to calculate thrust distribution: To solve the optimization problem consisting of boundary constraints and an evaluation function, methods such as sequential quadratic programming, interior point method, and particle swarm optimization can be used to determine the optimal forces acting on all thrusters and all anchor cables. The specific calculation process is not detailed here. The optimal force acting on all anchor cables is the magnitude and direction of the tension in each cable.

[0094] In this embodiment, only the thruster is considered in the evaluation function, and the virtual thruster (anchor cable) is not considered. When solving the problem using boundary constraints, both the thruster and the anchor cable are involved.

[0095] S3: Calculate the best anchoring solution based on the optimal force of the anchor cable.

[0096] The best anchoring solution in this step is the best combination of anchoring point position and anchor cable length. and anchor cable azimuth , an iterative method is used to calculate the optimal combination of anchor point position and anchor cable length.

[0097] For all The optimal combination of anchor point position and anchor cable length is calculated for each anchor cable. The optimal anchor point position of any anchor cable is located on a ray with its anchor hole as the starting point and the optimal anchor cable azimuth as the direction; the optimal anchor point position of the anchor cable is found by iterative calculation 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. The specific process is as follows:

[0098] S3.1: Select a point on the ray starting from the anchor hole of the anchor cable and oriented at the anchor cable azimuth. The corresponding seabed position of this point shall be the assumed anchoring point.

[0099] S3.2: Based on the target position of the vessel for the operation, the target heading, the position of the anchor hole relative to the center of the vessel, and the assumed anchor point, calculate the horizontal distance between the anchor hole and the assumed anchor point:

[0100]

[0101] in, is the north position of the target position of the ship's operation mission expressed in the north-east coordinate system, is the eastward position of the target position of the ship's operation mission expressed in the north-east coordinate system, is the target heading of the ship, For the The longitudinal offset of the anchor hole of the anchor cable relative to the center of the ship, For the The horizontal offset of the anchor hole of the anchor cable relative to the center of the ship, For the The north position of the anchor hole of the anchor cable in the northeast coordinate system, For the The east position of the anchor hole of the anchor cable in the northeast coordinate system, For the The north position of the anchor point of the anchor cable is assumed in the northeast coordinate system. For the The eastward position of the anchor point of the anchor cable in the northeast coordinate system is assumed to be: For the The horizontal distance between the anchor cables.

[0102] S3.3: Based on the horizontal distance and the anchor cable tension, use the catenary theory to calculate the anchor cable length:

[0103]

[0104] in, For the The length of the anchor cable, is the unit wet weight of the mooring line, which is a known quantity for anchor cables of known material. is the tension of the j-th anchor cable, and sinh() is the hyperbolic sine function.

[0105] S3.4: Determine whether the anchor cable length meets the actual conditions:

[0106]

[0107] in, It is the vertical height difference between the anchor hole and the assumed anchoring point, which can be measured by the water depth sensor; For the Maximum anchor cable length.

[0108] If the actual conditions are met, the current assumed anchoring point and anchor cable length are the optimal anchoring plan for the anchor cable;

[0109] If it does not meet the actual conditions, the position of the point is moved on the ray, the assumed anchor point is re-determined, and the process proceeds to S3.2.

[0110] Points are selected along the ray from closest to the vessel. The initial position of each point is twice the water depth, and the interval between each point movement is 0.1 times the water depth. An iterative calculation method is used to continuously adjust the position of the assumed anchoring point until the corresponding anchor cable length meets the actual conditions, resulting in a reasonable and feasible anchoring plan.

[0111] Figure 3 This is a schematic diagram of iterative calculation of the optimal anchor point for the anchor cable. Figure 3 The iterative selection process of the hypothetical anchoring point of anchor cable No. 1 is shown. The direction of the arrow in the figure is the anchor cable azimuth (ray direction). The initial position of the selected point is 2 times the draft from the anchor hole. A total of 8 hypothetical anchoring points are selected along the ray direction. For the anchoring point, the relative position of the anchor cable and its underwater posture are as follows: Figure 4 shown.

[0112] This embodiment also provides an anchoring decision system for an anchoring combined with a dynamic positioning system, such as Figure 5 As shown, the adopted technical solution is as follows: including: a data acquisition module 1, an anchor cable force calculation module 2 and an anchoring scheme calculation module 3.

[0113] The data acquisition module is used to obtain the target position and heading that the vessel must maintain during hovering, as well as environmental measurement information, and calculate the environmental interference loads to which the vessel will be subjected. The environmental interference loads include longitudinal, transverse, and heading wind loads, wave loads, and current loads.

[0114] The anchor cable force calculation module is used to distribute thrust based on environmental disturbance loads, aiming to minimize propeller energy consumption and wear, and calculate the optimal anchor cable force. The evaluation function only considers the propeller, not the virtual propeller (anchor cable). When solving using boundary constraints, both the propeller and the anchor cable are considered. The optimal anchor cable force is determined by the anchor cable tension and the anchor cable azimuth.

[0115] The anchoring solution calculation module is used to calculate the optimal anchoring solution based on the optimal force of the anchor cable. According to the anchor cable tension and anchor cable azimuth, the optimal combination of anchoring point position and anchor cable length is calculated in an iterative manner to obtain the optimal anchoring solution.

[0116] This invention is applicable to vessels equipped with dynamic positioning (DP), both single-anchor and multi-anchor systems, and is particularly useful for assisting in anchoring decision-making prior to conducting combined anchoring and positioning operations. This invention enables marine engineering vessels to conduct combined dynamic positioning (DP) control at anchoring in complex operating environments, providing intelligent, advance anchoring decision-making support. In the field of combined dynamic positioning (DP) systems for anchoring, this invention offers significant engineering value, distinct from other methods and irreplaceable.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An anchoring decision method for an anchoring combined with a dynamic positioning system, characterized in that: The following steps are involved: 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: Based on the environmental interference load, the thrust is distributed with the goal of minimizing the energy consumption and wear of the thruster, and the optimal force acting on the anchor cable is calculated; In S2, each anchor cable is regarded as a virtual thruster that can generate force. All thrusters and all anchor cables jointly generate control force acting on the ship, and boundary constraints are constructed. Considering only the propeller, the evaluation function is constructed with the goal of minimizing the propeller's energy consumption and wear; According to the boundary constraints and evaluation function, 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.

2. The anchoring decision method of an anchoring combined with dynamic positioning system according to claim 1, characterized in that: Environmental disturbance loads include longitudinal, transverse and bow wind loads, wave loads and flow loads.

3. The anchoring decision method of the anchoring combined dynamic positioning system according to claim 2, characterized in that: 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 transverse wind load on the ship, is the bow wind load on the ship; is the dimensionless wind load coefficient in the longitudinal direction of the hull, is the dimensionless wind load coefficient of the hull transverse direction, is the dimensionless wind load coefficient of the bow; 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 load coefficient of the bow; 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 flow load is: in, The current direction of the operating sea area; is the relative flow angle of the ship; is the longitudinal flow load on the ship, is the transverse flow load on the ship, is the bow flow load on the ship; is the dimensionless flow load coefficient in the longitudinal direction of the hull, is the dimensionless flow load coefficient in the transverse direction of the hull, is the dimensionless flow load coefficient of the bow direction of the hull; is the current flow velocity in the operating sea area; For the width of the ship, For draft; The calculation formula of environmental interference load is: in, is the longitudinal environmental disturbance load on the ship, is the lateral environmental disturbance load on the ship, is the bow environmental disturbance load on the ship.

4. The anchoring decision method of an anchoring combined with dynamic positioning system according to claim 1, characterized in that: The boundary constraints are as follows: in, To meet the control force requirements for ship dynamic positioning and to resist environmental interference loads. is the thrust vector of the propeller, is the thruster azimuth vector, The transformation matrix for converting all propeller thrust into the hull coordinate system; is the anchor cable tension vector, is the anchor cable azimuth vector, is the transformation matrix for converting all anchor cable tension into the ship coordinate system, It is the distribution error between the control force requirement and the actual control force; The maximum thrust limit of all thrusters, is the thrust vector of all thrusters at the previous moment, is the thrust variation limit of all thrusters within one control cycle, is the lower boundary of all thruster thrust azimuths, is the upper limit of all thruster thrust azimuths, is the thrust azimuth vector of all thrusters at the previous moment, is the thrust angle range change limit of all thrusters within one control cycle, The maximum tension limit of the anchor cable is is the lower boundary of the anchor cable tension azimuth, It is the upper boundary of the anchor cable tension azimuth.

5. The anchoring decision method of the anchoring combined dynamic positioning system according to claim 4, characterized in that: Evaluation function for: in, is the thrust of the i-th thruster, T represents the transposed matrix, is the accuracy penalty coefficient for thrust distribution, is the energy consumption penalty coefficient for thrust distribution, The wear penalty factor assigned to thrust.

6. The anchoring decision method of an anchoring combined with dynamic positioning system according to claim 1, characterized in that: The optimal forces acting on the anchor cable are the anchor cable tension and the anchor cable azimuth. In S3, the optimal combination of anchor point position and anchor cable length is calculated iteratively according to the anchor cable tension and anchor cable azimuth, and the optimal anchoring scheme is obtained.

7. The anchoring decision method of an anchoring combined with dynamic positioning system according to claim 6, characterized in that: The specific process of calculating the best anchoring solution is as follows: S3.1: Select a point on the ray starting from the anchor hole of the anchor cable and oriented at the anchor cable azimuth, and use the corresponding seabed position as the assumed anchoring point; S3.2: Calculate the horizontal distance between the anchor hole and the assumed anchor point; S3.3: Calculate the length of the anchor cable using the catenary theory based on the horizontal distance and anchor cable tension. S3.4: Determine whether the anchor cable length meets the actual conditions; If the actual conditions are met, the current assumed anchoring point and anchor cable length are the optimal anchoring plan for the anchor cable; If it does not meet the actual conditions, the position of the point is moved on the ray, the assumed anchor point is re-determined, and the process proceeds to S3.

2.

8. The anchoring decision method of an anchoring combined with dynamic positioning system according to claim 7, characterized in that: Points are selected from the ray in 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 0.1 times the water depth.

9. An anchoring decision system for an anchoring combined with a dynamic positioning system, characterized in that: The method for executing an anchoring decision-making method of an anchoring combined dynamic positioning system according to any one of claims 1 to 8 comprises: a data acquisition module, an anchor cable force calculation module and an anchoring scheme calculation module. 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 interference load that the ship will be subjected to; The anchor cable force calculation module is used to distribute thrust according to the environmental interference load and to minimize the energy consumption and wear of the thruster, and to calculate the optimal force of the anchor cable; The anchoring scheme calculation module is used to calculate the best anchoring scheme according to the optimal force of the anchor cable.

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