A ship-ice interaction parameter correction method based on historical channel information
Patent Information
- Application Number
- CN202410587555.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-13
- Publication Date
- 2026-09-29
- Estimated Expiration
- 2044-05-13
AI Technical Summary
但是目前经典主流的船体冰力(矩)计算方法仅针对船舶完全进入层冰区域以及航行前方层冰自由边界距船体足够远的情况，实际航行过程中其实并不一定满足这种情况，且实际航行时很容易出现船冰接触状态发生大幅度变化、船体部分区域发生冰力卸载的情况，此时直接使用目前经典主流的船体冰力(矩)计算方法计算得到的船体冰力(矩)很难准确表征船舶遭受的海冰作用参数，这将造成船舶冰区操纵运动仿真结果的准确性和合理性下降
[0012]本申请公开了一种基于历史航道信息的船冰作用参数修正方法，该方法对历史航行过程中不同时刻的船体水线的位置信息进行记录，可以用于确定当前时刻水线离散点与敞水区域和破冰航道的相对位置关系，从而确定当前时刻水线离散点与层冰接触状态，利用与层冰接触并会对当前船体运动状态下的的船冰作用参数有影响的水线离散点对船冰作用参数进行修正，修正后的船冰作用参数可以准确表征船舶受到的船冰作用力，为层冰区船舶任意操纵运动仿真提供准确的船体冰力(矩)输入，尤其是可以在船舶进出层冰区及航道交叉、重叠等船冰接触状态大幅变化、船体部分区域发生冰力卸载的情况下得到准确的船冰作用参数，从而有利于提高层冰区船舶任意操纵运动仿真的可靠性和准确性。
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Abstract
Description
Technical Field
[0001] This application relates to the field of ship maneuvering simulation technology in ice-covered areas, and in particular to a method for correcting ship-ice interaction parameters based on historical waterway information. Background Technology
[0002] Currently, all major polar research powers worldwide are accelerating their polar maritime strategic deployments. Polar vessels, as essential equipment for polar shipping and trade, waterway development and maintenance, and resource exploitation, have naturally become a new target for shipbuilding industries in various countries. The harsh polar environment necessitates significant differences between the design of polar vessels and conventional vessels. In addition to excellent open-water navigation performance, polar vessels must also possess superior ice-sea navigation and maneuverability.
[0003] To evaluate and optimize the ice-covered navigation and maneuvering performance of polar vessels, simulations of maneuvering motions within ice-covered regions are necessary during the vessel design and development process. Polar vessels experience powerful sea ice forces during navigation in ice-covered areas, and these forces have the greatest impact on the vessel's maneuvering response compared to other external forces such as wind, waves, and currents. Therefore, applying accurate sea ice parameters during simulation is crucial, directly determining the rationality and accuracy of the simulation results.
[0004] The traditional approach is to calculate the ship's ice force (moment) using the current mainstream methods and then input these parameters as sea ice effects onto the ship. However, these methods only apply when the ship is fully inside an ice-covered area and the free boundary of the ice layer ahead of the ship is sufficiently far from the hull. In actual navigation, these conditions are not always met. Furthermore, significant changes in the ship-ice contact state and ice unloading in parts of the hull are common occurrences. In such cases, the ice force (moment) calculated using these methods is insufficient to accurately represent the sea ice effects experienced by the ship, leading to a decrease in the accuracy and reliability of simulation results for ship maneuvering in ice-covered areas. Summary of the Invention
[0005] To address the aforementioned problems and technical requirements, this application proposes a method for correcting ship ice interaction parameters based on historical waterway information. The technical solution of this application is as follows:
[0006] A method for correcting ship ice interaction parameters based on historical waterway information, the method comprising:
[0007] The ship ice effect parameters at the current moment are calculated using the ship ice effect calculation method, and the ship waterline position information at the current moment and the ship waterline position information at each historical moment before the current moment are determined. The ship waterline position information at each moment includes the position of each discrete point on the ship waterline at the corresponding moment.
[0008] The effective discrete point at the current moment is determined based on the ship's motion state parameters at the current moment. The effective discrete point at the current moment is the waterline discrete point that affects the ship ice action parameters under the current ship motion state.
[0009] Based on the current waterline position information of the ship, combined with the waterline position information of the ship at various historical moments and the open water area information, it is determined whether each effective discrete point is in an ice-touch state or not.
[0010] The ship-ice interaction parameters at the current moment are corrected using the effective discrete points that are currently in the ice-touch state.
[0011] The beneficial technical effects of this application are:
[0012] This application discloses a method for correcting ship-ice action parameters based on historical waterway information. This method records the position information of the ship's waterline at different times during historical navigation, which can be used to determine the relative positional relationship between the current waterline discrete point and the open water area and icebreaking channel, thereby determining the contact state between the current waterline discrete point and the ice layer. The ship-ice action parameters are corrected using the waterline discrete point that is in contact with the ice layer and will affect the ship's current motion state. The corrected ship-ice action parameters can accurately characterize the ship-ice force acting on the ship, providing accurate ship-ice force (moment) input for simulating arbitrary ship maneuvering motion in ice-covered areas. In particular, it can obtain accurate ship-ice action parameters when the ship enters or leaves the ice-covered area, and when the ship-ice contact state changes significantly due to channel intersections and overlaps, and when ice force is unloaded in some areas of the ship. This is beneficial to improving the reliability and accuracy of simulating arbitrary ship maneuvering motion in ice-covered areas. Attached Figure Description
[0013] Figure 1 This is a flowchart of a method for correcting ship ice action parameters according to an embodiment of this application.
[0014] Figure 2 This is a schematic diagram of the waterline discretization points obtained by discretizing the waterline of the ship's hull.
[0015] Figure 3 This is a schematic diagram of the ship's waterline based on discrete points representing the waterline.
[0016] Figure 4 It is a schematic diagram of the icebreaking channel formed by the sequential arrangement of the ship's waterline at different times.
[0017] Figure 5 This is a schematic diagram of the effective discrete points determined under different motion states.
[0018] Figure 6 This is a flowchart illustrating the process of determining the state of valid discrete points according to an embodiment of this application.
[0019] Figure 7 This is a schematic diagram of an icebreaking channel intersection in an example, and a schematic diagram of the effective discrete points obtained in different states.
[0020] Figure 8 This is a schematic diagram illustrating the determination of the projected length of the hull waterline at any discrete point on the two coordinate axes of the hull plane coordinate system in one embodiment. Detailed Implementation
[0021] The specific embodiments of this application will be further described below with reference to the accompanying drawings.
[0022] This application discloses a method for correcting ship ice action parameters based on historical waterway information. Please refer to [link / reference]. Figure 1 The flowchart shown illustrates the ship's ice action parameter correction method, which includes:
[0023] Step 1: Calculate the ship ice effect parameters at the current moment using the ship ice effect calculation method, and determine the ship waterline position information at the current moment as well as the ship waterline position information at each historical moment before the current moment.
[0024] In one embodiment, the calculated ship-ice interaction parameters at the current moment include longitudinal ice force. Lateral ice force And ice torque The calculation method for ship-ice action can employ existing methods for calculating ship hull ice forces (moments). The calculated ship-ice action parameters for the current moment are obtained using the currently classic and mainstream methods for calculating ship hull ice forces (moments), and this application will not elaborate on the specific calculation process. However, the traditional approach directly applies the obtained ship-ice action parameters for the current moment to the ship, while this application incorporates a ship-ice action parameter correction method to correct the ship-ice action parameters for the current moment before applying them to the ship. This allows the corrected ship-ice action parameters for the current moment to more accurately represent the sea ice forces experienced by the ship.
[0025] The ship's waterline is discretized in advance, and the waterline is represented by a finite number of discrete points. Figure 2 The diagram shows the discrete points along the waterline when the ship is in its initial position. The closed curve formed by connecting these discrete points accurately represents the shape of the ship's waterline. Figure 3 As shown by the dashed line, the waterline of the ship can be accurately characterized by using discrete points on the waterline.
[0026] During the simulation of ship maneuvering in ice zones, the position of the ship's waterline changes as the ship's position changes. The waterline position information is recorded at predetermined time intervals, thus obtaining the waterline position information at multiple different times. Since the discretization method of the waterline points is fixed, meaning the relative position of each waterline point on the ship's waterline is fixed, recording the positions of each waterline point allows us to record the position of the ship's waterline. Therefore, the waterline position information at each time point includes the positions of all waterline points on the ship's waterline at that specific moment.
[0027] To better represent the positions of each discrete point on the waterline, a fixed coordinate system O-XY is pre-established. The O-XY system takes any point outside the waterline of the ship at its initial position as its origin O, the direction pointing from the origin to the bow of the ship at its initial position as the positive X-axis, and the direction pointing from the origin to the starboard side of the ship at its initial position as the positive Y-axis. Figure 2 and Figure 3 As shown, recording the position of each discrete point on the waterline in the fixed coordinate system O-XY at each moment can record the waterline position information of the ship at that moment.
[0028] Based on the collected waterline position information at each moment, the coverage area of the waterline at that moment can be determined. Since the ship's position varies at different times, the coverage area of the waterline at different moments often differs. Sequentially combining the waterline data from multiple consecutive moments can characterize the icebreaking channel for a ship navigating in layered ice. Figure 4 As shown, the recorded waterlines at various times are sequentially combined to form a continuous icebreaking channel, representing the ship's icebreaking navigation process. Figure 4 The image shows only a small section of the icebreaking channel. In reality, due to the diversity and complexity of the icebreaking process, icebreaking channels often intersect and overlap.
[0029] Step 2: Determine the effective discrete points for the current moment based on the ship's motion state parameters at the current moment.
[0030] The effective discrete points at the current moment are the waterline discrete points that affect the ship's ice-affecting parameters under the current ship motion state. While the total number of waterline discrete points is relatively large, not all of them necessarily affect the ice-affecting parameters. Which specific regions of waterline discrete points influence the ice-affecting parameters depends on the ship's motion state. Therefore, determining the effective discrete points at the current moment based on the ship's motion state parameters may result in the determination of all waterline discrete points or only a portion of them.
[0031] The ship's motion parameters at the current moment include its longitudinal velocity u, lateral velocity v, and bow roll rate r. Therefore, the effective discrete points at the current moment include:
[0032] (1) Determine the effective longitudinal discrete point at the current moment based on the longitudinal velocity u of the ship at the current moment. The effective longitudinal discrete point at the current moment is the waterline discrete point that affects the longitudinal ice force at the current moment.
[0033] Taking the direction pointing towards the bow as the positive direction of the ship's longitudinal velocity u, there are two different cases:
[0034] When the ship's longitudinal velocity v≥0 at the current moment, the waterline discrete points on the port side from the bow to the midpoint of the port side and the waterline discrete points on the starboard side from the bow to the midpoint of the starboard side are both valid longitudinal discrete points. Based on Figure 2 For example, when u≥0, the obtained effective longitudinal discrete points are determined as follows: Figure 5 In (a), the symbol is represented by a star.
[0035] When the ship's longitudinal velocity u < 0 at the current moment, the waterline discrete points on the port side from the stern to the midpoint of the port side and the waterline discrete points on the starboard side from the stern to the midpoint of the starboard side are both valid longitudinal discrete points. Based on Figure 2 For example, when u < 0, the obtained effective longitudinal discrete points are determined as follows: Figure 5 In (b) of the diagram, a star is used to represent the shape.
[0036] (2) Determine the effective lateral discrete point at the current moment based on the lateral velocity v of the hull at the current moment. The effective lateral discrete point at the current moment is the waterline discrete point that affects the lateral ice force at the current moment.
[0037] Taking the direction pointing to the starboard side of the hull as the positive direction of the hull's transverse velocity v, there are two different cases:
[0038] When the ship's transverse velocity v≥0 at the current moment, all waterline discrete points on the starboard side of the ship are determined to be valid transverse discrete points. Based on Figure 2 In the example, when v≥0, the obtained effective discrete points in the lateral direction are determined as follows: Figure 5 In (c), a star is used to represent the symbol.
[0039] When the ship's transverse velocity v < 0 at the current moment, all waterline discrete points on the port side of the ship are determined to be valid transverse discrete points. Based on Figure 2 For example, when v < 0, the obtained effective discrete points in the lateral direction are determined as follows: Figure 5 In (d), a star is used to represent the symbol.
[0040] (3) Determine the effective discrete point of torque at the current moment based on the current bow roll rate r. The effective discrete point of torque at the current moment is the waterline discrete point that affects the ice torque at the current moment.
[0041] Taking clockwise as the positive direction of the bow roll angular velocity r, there are two different cases:
[0042] When the bow roll rate r ≥ 0 at the current moment, the discrete points on the waterline from the stern to the midpoint of the port side of the hull and the discrete points on the waterline from the bow to the midpoint of the starboard side of the hull are both effective discrete points of the moment. Based on Figure 2 For example, when r≥0, the effective discrete point of the obtained torque is determined to be in the following position: Figure 5 In (e), a star is used to represent the symbol.
[0043] When the current bow roll rate r < 0, the discrete points on the waterline from the bow to the midpoint of the port side of the hull and the discrete points on the waterline from the stern to the midpoint of the starboard side of the hull are both effective discrete points of the moment. Based on Figure 2 For example, when r < 0, the effective discrete point of the obtained torque is determined to be in the following position: Figure 5 In (f), a star symbol is used.
[0044] Since the ship's motion parameters at the current moment include three parameters: longitudinal velocity *u*, transverse velocity *v*, and yaw rate *r*, any waterline discrete point that is a valid discrete point may belong to one or more of the following categories: longitudinal valid discrete point, transverse valid discrete point, and moment valid discrete point. For example, when *u* ≥ 0, *v* ≥ 0, and *r* ≥ 0 at the current moment, combined with... Figure 5 (a), (c), and (e) in the diagram can determine that each waterline discrete point on the starboard side of the hull, from the bow to the midpoint of the starboard side, is a longitudinally effective discrete point, a transversely effective discrete point, and a moment effective discrete point. Other points can be deduced similarly.
[0045] Step 3: Based on the current waterline position information of the ship's hull, combined with the waterline position information of the ship's hull and the open water area information at various historical moments, determine whether each effective discrete point is in an ice-touch state or not.
[0046] As described in step 2, there are a large number of discrete points above the waterline of the ship's hull. However, depending on the ship's motion state, not all discrete points will necessarily affect the ship's ice-affecting parameters; only effective discrete points will have an impact. Although theoretically all effective discrete points will affect the ship's ice-affecting parameters, in reality, not all effective discrete points will necessarily make a substantial contribution to the ship's ice-affecting parameters.
[0047] When ships enter or exit ice-covered areas, or when icebreaking channels intersect or overlap, significant changes occur in the ship-ice contact state, and ice force unloading occurs in parts of the hull. These situations result in some waterline discrete points contacting the ice, while others do not. Therefore, some effective discrete points may be in an ice-free state, while others may be in contact with the ice. Effective discrete points in an ice-free state, while not in contact with the ice, theoretically influence the ship-ice interaction parameters, but in practice do not make a substantial contribution. Only effective discrete points in contact with the ice contribute substantially to the ship-ice interaction parameters. Therefore, it is necessary to determine whether each effective discrete point is in an ice-free or ice-touch state to identify which effective discrete points will make a substantial contribution to the ship-ice interaction parameters.
[0048] This application first determines the effective discrete points, and then further determines whether the effective discrete points are in contact with ice or not. This eliminates the need to determine whether other waterline discrete points that are not effective discrete points are in contact with ice, thereby reducing redundant computation and improving efficiency.
[0049] In one embodiment, the method for determining whether a valid discrete point is in contact with layer ice includes: determining the relative positional relationship between each valid discrete point and the open water area based on the ship's waterline position information at the current moment combined with open water area information; and determining the relative positional relationship between each valid discrete point and the icebreaking channel based on the ship's waterline position information at the current moment combined with ship's waterline position information at various historical moments. The open water area information indicates the coverage area of the open water area and can be predetermined, for example... Figure 7 In the diagram, the area to the left of the dotted line represents the known open water area, and the area to the right represents the known layered ice area.
[0050] When a valid discrete point is located in open water or within an icebreaking channel, it is determined to be in a non-ice-contact state; otherwise, it is determined to be in an ice-contact state. For details, please refer to [link / reference needed]. Figure 6 Flowchart and combined Figure 7 A schematic diagram, Figure 7 A partial schematic diagram of the icebreaking channel intersection is shown:
[0051] (1) Initialize each valid discrete point at the current moment to a state to be determined. Based on the ship's waterline position information and open water area information at the current moment, detect whether each valid discrete point is located within the open water area. Change the valid discrete points located within the open water area from the state to the non-ice-touch state, while the valid discrete points located outside the open water area remain in the state to be determined. In particular, if all valid discrete points are located within the open water area, the ice-touch state of all valid discrete points has been determined in this step. If there are still valid discrete points in the state to be determined, continue to execute the following step (2).
[0052] (2) Construct a bounding box for the ship's waterline position at the current moment. The constructed bounding box is generally a rectangular bounding box. Existing methods can be used for the specific construction method, such as... Figure 7 The bounding box constructed in the middle is shown as a dashed line.
[0053] (3) Initialize integer parameter j = 1. Based on the hull waterline position information at the j-th historical moment, detect whether there are discrete points on the hull waterline at the j-th historical moment that are inside the bounding box.
[0054] (4) When there are discrete points on the waterline of the ship at the j-th historical moment that are inside the bounding box, the positions of each valid discrete point on the waterline of the ship at the current moment that is in an undetermined state are traversed in turn.
[0055] For any valid discrete point encountered, if the position of the valid discrete point is determined to be inside the waterline of the ship at the j-th historical moment, based on the ship's waterline position information, then the valid discrete point is determined to be within the icebreaking channel, and its state is changed from pending determination to non-ice-touch state. Otherwise, the valid discrete point remains in the pending determination state. Valid discrete points located in open water areas are always in a non-ice-touch state, but valid discrete points located in layered ice areas are not necessarily so. Valid discrete points located in layered ice areas are only in a non-ice-touch state if they are located within the icebreaking channel.
[0056] After traversing all valid discrete points in an undetermined state on the waterline at the current moment, let j = j+1 and repeat the step of checking whether there are any discrete points on the waterline at the j-th historical moment inside the bounding box, until there are no more valid discrete points in an undetermined state or until all historical moments have been traversed. The (j+1)-th historical moment is a historical moment following the j-th historical moment according to a predetermined traversal order. The predetermined traversal order can be the chronological order of the historical moments or its reverse chronological order, or it can be a user-defined order.
[0057] (5) When all the discrete points on the waterline of the ship at the j-th historical moment are not inside the bounding box, let j = j + 1 and execute the step of checking whether there are discrete points on the waterline of the ship at the j-th historical moment inside the bounding box again, until there are no valid discrete points that are still in an undetermined state or until all historical moments have been traversed.
[0058] (6) After traversing all historical moments' waterline position information, valid discrete points that are still in an undetermined state are changed from an undetermined state to an ice-touch state. For example, in Figure 7 In the example, black dots represent valid discrete points in a non-ice-touching state, while * represents valid discrete points in an ice-touching state.
[0059] Step 4: Correct the ship-ice interaction parameters at the current moment using the effective discrete points that are currently in the ice-touch state.
[0060] The ice-affecting parameters refer to the longitudinal ice force, lateral ice force, and ice moment acting on the ship. Correcting the ice-affecting parameters at the current moment involves three aspects. Assume that at the current moment, a total of N effective longitudinal discrete points, M effective lateral discrete points, and Q effective moment discrete points are determined, where N, M, and Q are integer parameters and N≥0, M≥0, and Q≥0. Among these, there are n effective longitudinal discrete points in ice contact, m effective lateral discrete points in ice contact, and q effective moment discrete points in ice contact, where n, m, and q are integer parameters and 0≤n≤N, 0≤m≤M, and 0≤q≤Q.
[0061] (1) Correction for longitudinal ice force: When n≥1, the longitudinal ice force at the current moment is corrected using the n effective discrete points in the current touching state. Make corrections; the corrected vertical ice force X at the current moment. ice :
[0062]
[0063] in, It is the contribution weight of the i-th effective longitudinal discrete point currently in the ice-touch state to the longitudinal ice force, with integer parameters 1≤i≤n.
[0064] (2) Correction for lateral ice force: When m≥1, the lateral ice force at the current moment is corrected using the m effective discrete points in the current touching state. Make corrections; the corrected lateral ice force Y at the current moment. ice :
[0065]
[0066] in, It is the contribution weight of the j-th effective lateral discrete point currently in the ice-touch state to the lateral ice force, with integer parameters 0≤j≤m.
[0067] (3) Correction of ice torque: When q≥1, the ice torque at the current moment is corrected by using the q effective discrete points of the torque at the current moment that are in the ice-touching state. Make corrections; the corrected ice torque N at the current moment. ice :
[0068]
[0069] in, It is the contribution weight of the kth effective discrete point of the torque that is currently in the ice-touching state to the ice torque, with integer parameters 1≤k≤q.
[0070] In the process of correcting the longitudinal ice force, lateral ice force, and ice moment, it is necessary to calculate the contribution weight of each effective discrete point to the longitudinal ice force, lateral ice force, and ice moment. This contribution weight can be customized based on experience, or, to make the contribution weight more accurately represent the contribution of each effective discrete point to the longitudinal ice force, lateral ice force, and ice moment, its contribution weight can be determined based on the location of the effective discrete point.
[0071] In one embodiment, to determine the contribution weight of any discrete point p on the waterline at the current moment to the longitudinal ice force, lateral ice force, and ice moment, the projected lengths of the waterline near that discrete point p on the x-axis and y-axis of the hull's plane coordinate system are first determined. Please refer to... Figure 8 The ship's current plane coordinate system G-xy has its origin at the projection point G of the ship's center of gravity onto the waterline, the positive x-axis pointing from the origin to the bow, and the positive y-axis pointing from the origin to the starboard side. Please refer to [reference needed]. Figure 8 Based on the coordinates of any discrete waterline point p in the fixed coordinate system O-XY, and combined with the ship's real-time position information, the coordinates (x, y) of that discrete waterline point p in the ship's hull plane coordinate system G-xy can be transformed and determined. p y p ), and the coordinates (x, y) of another waterline discrete point p-1 adjacent to the waterline discrete point p on one side in the ship's plane coordinate system G-xy. p-1 y p-1 ), and the coordinates (x) of another waterline discrete point p+1 adjacent to the waterline discrete point p on the other side in the ship's plane coordinate system G-xy. p+1 y p+1 Since the waterline of the ship's hull is a closed curve, any discrete point on the waterline has two adjacent discrete points on either side.
[0072] Then, the coordinates of the center point of the line connecting the waterline discrete point p and the waterline discrete point p-1 in the ship's plane coordinate system G-xy are calculated as follows: And the coordinates of the center point of the line connecting the waterline discrete point p and the waterline discrete point p+1 in the ship's plane coordinate system G-xy are calculated as follows:
[0073] Finally, the center point of the line connecting the discrete waterline point p and the discrete waterline point p-1 is projected onto the x-axis and y-axis of the ship's plane coordinate system G-xy, respectively. Similarly, the center point of the line connecting the discrete waterline point p and the discrete waterline point p+1 is projected onto the x-axis and y-axis of the ship's plane coordinate system G-xy, respectively. The projection length of the waterline near the current discrete waterline point p onto the x-axis of the ship's plane coordinate system G-xy can be determined as follows. The projection length of the waterline near the current waterline discrete point p onto the y-axis of the hull plane coordinate system G-xy is determined as follows.
[0074] Using the method described above, the projected lengths of the ship's waterline at the current moment on the x-axis and y-axis of the ship's planar coordinate system G-xy at any vicinity of any valid discrete point can be determined. The types of projected lengths used to calculate the contribution weights of any valid discrete point to longitudinal ice forces, lateral ice forces, and ice moments are different, and are described below:
[0075] (1) For each longitudinally effective discrete point, the projection length on the y-axis is mainly used. Therefore, based on the position of any s-th longitudinally effective discrete point at the current time, the projection length of the hull waterline near the s-th longitudinally effective discrete point on the y-axis of the hull plane coordinate system G-xy at the current time can be determined using the method described above.
[0076] If the number of longitudinally valid discrete points determined based on the current hull motion state is N, then when N≥1, the contribution weight of any s-th longitudinally valid discrete point at the current time to the longitudinal ice force can be determined.
[0077] (2) For each effective lateral discrete point, the projection length on the x-axis is mainly used. When M≥1, the projection length of the hull waterline near the t-th effective lateral discrete point at the current time on the x-axis of the hull plane coordinate system G-xy is determined according to the position of any t-th effective lateral discrete point at the current time, following the method described above.
[0078] If the number of effective lateral discrete points determined based on the current hull motion state is M, then the contribution weight of any t-th effective lateral discrete point to the lateral ice force at the current time can be determined.
[0079] (3) For each effective discrete point of torque, both the projected length on the x-axis and the projected length on the y-axis need to be used. Therefore, based on the position of any h-th effective discrete point of torque at the current time, the projected length of the hull waterline near the h-th effective discrete point of torque at the current time on the x-axis of the hull plane coordinate system G-xy is determined according to the method described above. and the projection length of the hull waterline near the h-th effective discrete point of moment on the y-axis of the hull plane coordinate system G-xy.
[0080] If the number of effective discrete points of torque determined based on the current hull motion state is Q, then when Q≥1, the contribution weight of any h-th effective discrete point of torque at the current time to the ice torque can be determined. The coordinates of the h-th effective discrete point of the torque in the hull plane coordinate system G-xy are (xh, yh).
[0081] As can be seen from the above introduction, the projection length used when calculating the contribution weight of different types of effective discrete points is different. In fact, only the required projection length needs to be calculated. For example, when a waterline discrete point is only a longitudinal effective discrete point, only the projection length of the hull waterline near that waterline discrete point at the current moment on the y-axis of the hull plane coordinate system needs to be calculated, without calculating the projection length on the x-axis, thus reducing the amount of computation. The classic mainstream method for calculating ship-ice forces calculates the ship-ice force (moment), which is usually the ship-ice force (moment) when all effective contact points are in contact with the ice, denoted as . and Therefore in and In the original text, all valid discrete points contribute to the numerical magnitude; however, when ships enter or exit ice layers, cross or overlap channels, only some valid discrete points come into contact with the ice and contribute to the ice force. The actual ship hull ice force (moment) X ice Y ice With N ice The size should be reduced accordingly, and the basis for the reduction is and Therefore, when calculating the contribution weight of an effective waterline discrete point in contact with ice to the ice force (moment) of the hull, this application assumes that all effective discrete points are in contact with ice.
[0082] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.
Claims
1. A method for correcting ship ice action parameters based on historical waterway information, characterized in that, The method for correcting ship ice action parameters includes: The ship ice effect parameters at the current moment are calculated using the ship ice effect calculation method, and the ship waterline position information at the current moment and the ship waterline position information at each historical moment before the current moment are determined. The ship waterline position information at each moment includes the position of each discrete point on the ship waterline at that moment. The effective discrete point at the current moment is determined based on the ship's motion state parameters at the current moment. The effective discrete point at the current moment is the waterline discrete point that affects the ship ice action parameters under the current ship motion state. Based on the current waterline position information of the ship, combined with the waterline position information of the ship at various historical moments and the open water area information, it is determined whether each effective discrete point is in an ice-touch state or not. The ship-ice interaction parameters at the current moment are corrected using the effective discrete points that are currently in the ice-touch state.
2. The method for correcting ship ice action parameters according to claim 1, characterized in that, Determining whether each valid discrete point is in an ice-touch or non-ice-touch state includes: The relative position of each effective discrete point to the open water area is determined based on the current waterline position information of the ship and the open water area information. The relative position of each effective discrete point to the icebreaking channel is determined based on the current waterline position information of the ship and the waterline position information of the ship at various historical times. When a valid discrete point is located in an open water area or an icebreaking channel, the valid discrete point is determined to be in a non-ice-contact state; otherwise, the valid discrete point is determined to be in an ice-contact state.
3. The method for correcting ship ice action parameters according to claim 2, characterized in that, Determining whether each valid discrete point is in an ice-touch or non-ice-touch state also includes: Initialize each valid discrete point to a state to be determined; Based on the current hull waterline position information and open water area information, detect whether each valid discrete point is located within the open water area. Valid discrete points located within the open water area are changed from the undetermined state to the non-ice-touch state, while valid discrete points located outside the open water area remain in the undetermined state. When there are still valid discrete points in an undetermined state, construct the bounding box of the ship's waterline at the current moment based on the ship's waterline position information at the current moment. Initialize integer parameter j = 1, and based on the hull waterline position information at the j-th historical moment, detect whether there are discrete points on the hull waterline at the j-th historical moment inside the bounding box; When there are discrete points on the waterline of the ship at the j-th historical moment that are inside the bounding box, the positions of each valid discrete point in the undetermined state on the waterline of the ship at the current moment are traversed sequentially. For any valid discrete point traversed, if the position of the valid discrete point is determined to be inside the waterline of the ship at the j-th historical moment based on the waterline position information of the ship at the j-th historical moment, the valid discrete point is determined to be within the icebreaking channel and the valid discrete point is changed from the undetermined state to the non-ice-touch state; otherwise, the valid discrete point remains in the undetermined state. After traversing all valid discrete points in the undetermined state on the waterline of the ship at the current moment, let j = j + 1 and execute the step of detecting whether there are discrete points on the waterline of the ship at the j-th historical moment that are inside the bounding box again, until there are no valid discrete points still in the undetermined state or until all historical moments have been traversed. When all discrete points on the waterline of the ship at the j-th historical moment are not inside the bounding box, let j = j + 1 and execute the step of detecting whether there are discrete points on the waterline of the ship at the j-th historical moment inside the bounding box again, until there are no valid discrete points that are still in the undetermined state or until all historical moments have been traversed. When all historical waterline position information of the ship has been traversed, the valid discrete points that are still in an undetermined state will be changed from an undetermined state to an ice-touch state.
4. The method for correcting ship ice action parameters according to claim 1, characterized in that, The ship-ice interaction parameters include longitudinal ice force, lateral ice force, and ice moment. These parameters are corrected using valid discrete points currently in contact with the ice, including: When n≥1, the longitudinal ice force at the current moment is obtained by using the n effective discrete points in the current touching state in the longitudinal direction. Make corrections; the corrected vertical ice force at the current moment. Among them, the effective longitudinal discrete points at the current moment are the waterline discrete points that affect the longitudinal ice force at the current moment. It is the contribution weight of the i-th effective longitudinal discrete point currently in the ice-touch state to the longitudinal ice force, with integer parameters 1≤i≤n, where n is an integer parameter; When m≥1, the lateral ice force at the current moment is obtained by using the m effective discrete points in the current lateral state that are in contact with ice. Make corrections; the corrected lateral ice force at the current moment. Among them, the effective lateral discrete points at the current moment are the waterline discrete points that affect the lateral ice force at the current moment. It is the contribution weight of the j-th effective lateral discrete point currently in the ice-touch state to the lateral ice force, with integer parameters 1≤j≤m, where m is an integer parameter; When q≥1, the ice torque at the current moment is obtained by using the q effective discrete points of the torque at the current moment that are in the ice-touching state. Make corrections; the corrected ice torque at the current moment. Among them, the effective discrete points of the torque at the current moment are the discrete points of the waterline that affect the ice torque at the current moment. It is the contribution weight of the kth effective discrete point of the torque that is currently in the ice-touching state to the ice torque, with integer parameters 1≤k≤q, where q is an integer parameter.
5. The method for correcting ship ice action parameters according to claim 4, characterized in that, The effective discrete points at the current moment are determined based on the ship's motion state parameters at the current moment, including: Determine the effective longitudinal discrete point at the current moment based on the ship's longitudinal velocity at the current moment; The effective lateral discrete point at the current moment is determined based on the ship's lateral velocity at the current moment; The effective discrete point of torque at the current moment is determined based on the current bow angular velocity.
6. The method for correcting ship ice action parameters according to claim 5, characterized in that, Determining the effective discrete points at the current moment based on the ship's motion state parameters at the current moment also includes: When the ship's longitudinal velocity u≥0 at the current moment, the waterline discrete points on the port side from the bow to the midpoint of the port side and the waterline discrete points on the starboard side from the bow to the midpoint of the starboard side are both valid longitudinal discrete points; when the ship's longitudinal velocity u<0 at the current moment, the waterline discrete points on the port side from the stern to the midpoint of the port side and the waterline discrete points on the starboard side from the stern to the midpoint of the starboard side are both valid longitudinal discrete points; where the longitudinal velocity u is positive in the direction pointing towards the bow; When the ship's transverse velocity v≥0 at the current moment, all waterline discrete points on the starboard side of the ship are determined to be valid transverse discrete points; when the ship's transverse velocity v<0 at the current moment, all waterline discrete points on the port side of the ship are determined to be valid transverse discrete points; where the transverse velocity v is defined as the direction pointing to the starboard side of the ship. When the current bow roll rate r ≥ 0, the discrete points on the waterline from the stern to the midpoint of the port side of the hull and the discrete points on the starboard side from the bow to the midpoint of the starboard side are both effective discrete points of torque; when the current bow roll rate r < 0, the discrete points on the waterline from the bow to the midpoint of the port side of the hull and the discrete points on the starboard side from the stern to the midpoint of the starboard side are both effective discrete points of torque; wherein, the bow roll rate r is positive in the clockwise direction.
7. The method for correcting ship ice action parameters according to claim 4, characterized in that, When the total number of effective longitudinal discrete points N≥1, determine the contribution weight of each effective longitudinal discrete point to the longitudinal ice force at the current time, including: Based on the position of any s-th longitudinal effective discrete point at the current time, determine the projection length of the hull waterline at the s-th longitudinal effective discrete point on the y-axis of the hull plane coordinate system. Determine the contribution weight of any s-th effective longitudinal discrete point to the longitudinal ice force at the current time. In this system, the ship's plane coordinate system G-xy at the current moment takes the projection point G of the ship's center of gravity onto the waterline as the origin, the direction from the origin to the bow of the ship as the positive x-axis, and the direction from the origin to the starboard side of the ship as the positive y-axis.
8. The method for correcting ship ice action parameters according to claim 4, characterized in that, When the total number of effective longitudinal discrete points M ≥ 1, determine the contribution weight of each effective transverse discrete point to the transverse ice force at the current moment, including: Based on the position of any t-th effective lateral discrete point at the current time, determine the projection length of the hull waterline at the t-th effective lateral discrete point on the x-axis of the hull plane coordinate system. Determine the contribution weight of any t-th effective lateral discrete point to the lateral ice force at the current time. In this system, the ship's plane coordinate system G-xy at the current moment takes the projection point G of the ship's center of gravity onto the waterline as the origin, the direction from the origin to the bow as the positive x-axis, and the direction from the origin to the starboard side as the positive y-axis.
9. The method for correcting ship ice action parameters according to claim 4, characterized in that, When the total number of effective longitudinal discrete points Q≥1, determine the contribution weight of each effective discrete point of the moment to the ice moment, including: Based on the position of any h-th effective moment discrete point at the current time, determine the projection length of the hull waterline at the h-th effective moment discrete point on the x-axis of the hull plane coordinate system. And the projected length of the hull waterline at the h-th effective discrete point of the moment on the y-axis of the hull plane coordinate system. Determine the contribution weight of any h-th effective discrete point of torque at the current time to the ice torque. In the current hull plane coordinate system G-xy, the origin is the projection point G of the ship's center of gravity onto the waterline, the positive x-axis is the direction pointing from the origin to the bow, and the positive y-axis is the direction pointing from the origin to the starboard side. The coordinates of the h-th effective moment discrete point in the hull plane coordinate system G-xy are (x h y h ).
10. The method for correcting ship ice action parameters according to any one of claims 7-9, characterized in that, Determine the projected lengths of the ship's waterline at any discrete waterline point p at the current moment on the x-axis and y-axis of the ship's planar coordinate system, including: Determine the coordinates (x, y) of the discrete point p on the waterline in the ship's hull plane coordinate system G-xy. p y p ), and the coordinates (x, y) of another waterline discrete point p-1 adjacent to the waterline discrete point p on one side in the ship's plane coordinate system G-xy. p-1 y p-1 ), and the coordinates (x) of another waterline discrete point p+1 adjacent to the waterline discrete point p on the other side in the ship's plane coordinate system G-xy. p+1 y p+1 ); The coordinates of the center point of the line connecting the waterline discrete point p and the waterline discrete point p-1 in the ship's plane coordinate system G-xy are calculated as follows: The coordinates of the center point of the line connecting the waterline discrete point p and the waterline discrete point p+1 in the ship's plane coordinate system G-xy are calculated as follows: The projection length of the waterline at the current discrete point p on the x-axis of the hull plane coordinate system is determined as follows: The projection length of the waterline at the current discrete point p on the hull plane coordinate system is determined as follows: