Simulation system and simulation modeling method for polar ship navigation

Abstract

The present invention relates to the field of naval architecture and ocean engineering. Disclosed are a simulation system and simulation modeling method for polar ship navigation. The problems of the impact of ice on the ship motion performance being mainly considered, and the consideration of the impact of crushed ice on the thrust of a screw lacking in an existing polar ship navigation are solved. The present invention provides the following solution. The system comprises subsystems such as a comprehensive management and assessment subsystem, and a ship six-degree-of-freedom motion model is constructed; a thrust calculation model is constructed in order to solve the problem of the impact of crushed ice in the screw propulsion process; crushed ice is used as an independent moving object to solve the ice crushing motion and obtain the relative movement speed of a ship and crushed ice; the impact of crushed ice on the performance of the screw is considered in the screw modeling process by incorporating the relative speed of the ship and crushed ice, and acts on the thrust calculation model; and an annular crack method is used to determine the flat ice crushing shape, and the generated crushed ice is close to the real one. The present invention is also applicable to the field of specific simulated navigation training provided for sailors navigating in polar regions.

Description

Polar ship navigation simulation system and modeling method TECHNICAL FIELD

[0001] The present application belongs to the technical field of ship and ocean engineering, and particularly relates to a polar ship navigation simulation system and a modeling method. BACKGROUND

[0002] With the opening of the Arctic route, the safety problem of polar ship navigation is increasingly serious. Polar dangerous environment, navigation characteristics, ice load, etc. are closely related to the safety and efficiency of polar ship navigation. The polar ship navigation simulation system can be used to provide specific simulated navigation training for crew in ice area, reserve driving theory basis and practical skills for entering polar navigation, further understand the special environment of polar sea area, and maximize the reduction of navigation risk. The physical realism, behavior realism and environmental realism of the polar ship navigation simulation system are important factors affecting the training effect.

[0003] Patent document CN116011294A discloses a method for building a six-degree-of-freedom ROV operation simulation platform, and proposes that the six-degree-of-freedom dynamics model building method of the mother ship cannot consider the influence factors of polar environment ship navigation, and is not suitable for ship polar navigation motion calculation. Based on the problems in the prior art, a six-degree-of-freedom motion simulation model of a polar ship and a ship-flat ice / ice collision simulation model are established to establish a simulation system, ensure the physical realism, behavior realism and environmental realism of the ship, ice and marine environment, and have important significance for improving the performance and training functionality of the simulation system.

[0004] The existing polar ship navigation simulation system has the following deficiencies:

[0005] 1. Insufficient ice effect on hydrodynamics: the polar ship navigation mainly considers the influence of ice on the motion performance of the ship, and lacks consideration of the influence of broken ice on the propeller thrust.

[0006] 2. Contradiction between real-time and accuracy of ice load calculation: it is difficult to ensure the real-time requirement by using discrete element or finite element method to calculate the ice load, and the experience formula method is fast but cannot produce actual broken ice.

[0007] 3. Single ice material parameters: the characteristics of polar ice materials are not single in the sea area, so the ice thickness, density and strength data need to be changed in real time. SUMMARY

[0008] The present application aims at the following technical problems in the prior art: firstly, the influence of ice on water power is insufficient: the influence of ice on the motion performance of the ship is mainly considered in polar ship navigation, and the influence of broken ice on the thrust of the propeller is not considered. Secondly, the real-time and accuracy of ice load calculation are contradictory: it is difficult to ensure the real-time requirement by using discrete element or finite element method to calculate the ice load, and the experience formula method is fast but cannot produce actual broken ice. Finally, the ice material parameters are single: the material properties of polar ice are not single in the sea area, so the ice thickness, density and strength data need to be changed in real time.

[0009] In order to overcome all the deficiencies in the prior art, the present application proposes the following technical solutions,

[0010] Scheme one, a polar ship navigation simulation system, the polar ship navigation simulation system includes a comprehensive management and evaluation subsystem, a ship driving control simulation subsystem, a polar operation environment simulation subsystem, a polar ship real-time motion simulation subsystem and a polar ship real-time motion simulation subsystem;

[0011] The comprehensive management and evaluation subsystem includes a trainer software and an electronic chart software, the trainer software is used to provide the polar environment and ice layer distribution input conditions for the polar operation environment simulation subsystem; the electronic chart software is used to provide the initial position and route planning of the ship for the polar ship motion simulation subsystem in real time, and control the simulation process of the simulation system at the same time;

[0012] The ship real-time motion simulation subsystem includes a propeller operation module, a rudder operation module, a driving and navigation control module; used to provide the propeller speed, rudder angle and propeller fault control instructions for the polar ship real-time motion simulation subsystem, used to simulate the ship navigation control;

[0013] The polar operation environment simulation subsystem includes a wind speed module, a wave field module, a flow rate module, an ice field module; and establishes a ship-flat ice collision model and a ship-broken ice collision model, calculates the polar environment load, ice load, ice breaking and motion data;

[0014] The polar ship real-time motion simulation subsystem includes a propeller module, a rudder module and a ship body module, by establishing a ship six-degree-of-freedom motion simulation model, the ship motion considering the influence of wind, wave, flow and ice load is calculated;

[0015] The polar ship navigation visual simulation subsystem receives the ice breaking and motion data calculated by the polar operation environment simulation subsystem, and the ship motion data calculated by the polar ship real-time motion simulation subsystem, used to display and update the polar navigation, atmosphere, ocean and ice field scene in real time.

[0016] Further, a preferred embodiment is provided, wherein the polar ship navigation visual simulation subsystem comprises a polar ship motion simulation driving module, a sea ice motion simulation driving module, a polar environment simulation module, and a polar navigation auxiliary information display module;

[0017] The polar ship motion simulation driving module is configured to receive and update in real time the motion position of the polar ship during navigation.

[0018] The sea ice motion simulation driving module is configured to receive and update in real time the ice distribution in the ship navigation area.

[0019] The polar environment simulation module is configured to update the polar environment synchronously according to the instructor's instruction.

[0020] The polar navigation auxiliary information display module is configured to dynamically display the ice layer thickness and interference distance in the visual scene.

[0021] Scheme II, a polar ship navigation simulation modeling method, which is implemented by using the system of any one of scheme I, and comprises the following steps:

[0022] Step I, set the environmental conditions, sea ice conditions, initial position of the ship, and expected navigation trajectory by the instructor software of the comprehensive management and evaluation subsystem and the electronic chart software, and issue a simulation task;

[0023] Step II, according to the simulation task issued in step I, the polar environment simulation subsystem calculates the wind, wave, and flow loads by the wind speed module, wave field module, and flow speed module according to the set environmental conditions, and uses the multi-thread parallel programming method to traverse the ship-waterline surface boundary points and the nearby flat ice and broken ice boundary points to detect the ship-ice contact situation.

[0024] Step III, based on the detection of the ship-ice contact situation in step II, when the ship-ice contact is detected, the ice field module calculates the flat ice breaking, broken ice motion, and total load of flat ice and broken ice according to the sea ice distribution, ice layer thickness, and material properties according to the ship-flat ice collision model and the ship-broken ice collision model.

[0025] Step IV, the polar ship real-time motion simulation subsystem takes the wind load, wave load, relative speed of the ship and sea current, total load of flat ice, and total load of broken ice calculated by the polar environment simulation subsystem as environmental load input, and takes the rotation speed and rudder angle provided by the polar ship driving control simulation subsystem as control instruction input, to respectively establish the propeller model, rudder model, and polar ship six-degree-of-freedom motion simulation model.

[0026] Step 5: The polar vessel navigation visual simulation subsystem generates a 3D scene based on the navigation sea area and wind, wave and current environmental conditions released by the instructor software. It updates the distribution of flat ice and broken ice according to the flat ice breaking characteristic data and broken ice motion data calculated by the polar environment simulation subsystem. It also updates the polar vessel navigation simulation 3D scene according to the vessel navigation motion data calculated by the polar vessel real-time motion simulation subsystem.

[0027] Furthermore, a preferred embodiment is provided, in which step three further includes calculating the contact area between the ship and ice, the compressive force and friction between the ship and ice, and the bending failure load of the flat ice, to determine the breakage of the flat ice, and representing the shape characteristics of the broken ice after the flat ice breaks by the radius of the broken ice fragments and the opening angle of the ice wedge.

[0028] Furthermore, a preferred embodiment is provided, in which step three calculates the contact area between the ship and ice, the compressive and frictional forces between the ship and ice, and the bending failure load of the flat ice to determine the breakage condition of the flat ice. The shape characteristics of the broken ice fragments after the flat ice breaks are represented by the radius of the detached ice fragments and the opening angle of the ice wedge. Specifically, the steps include:

[0029] S31, First, by measuring the ice thickness h i The angle between the ship's external normal and the downward vertical axis at the point of contact with ice. and extrusion depth L d Determine the shape of the contact point between the ship and the ice, and calculate the contact area A between the ship and the smooth ice. c The collision model for the ship-flat ice is as follows:

[0030] Among them, L h L is the length of the ship's boundary on the horizontal ice surface, in contact with the ice boundary; d The depth to which a ship is pressed into the ice boundary on a horizontal ice surface; h is the angle between the ship's external normal at the point of contact with the ice and the downward vertical axis; i This refers to the thickness of the ice layer.

[0031] S32, Secondly, through the contact area A between the ship and the smooth ice. c Calculate the compressive force F between the ship and the ice respectively. c and frictional force F f The collision model for the ship-flat ice is: F c =n c ·σ c A c F fz =-τ c μ f F c v z / VF fl =-τ c μf F c v l / V

[0032] where n c is the unit normal of the ship-ice contact surface; σ c is the compressive strength of ice; τ c is the unit tangential of the ship-ice contact surface; μ f is the friction coefficient of ship-ice; F fz is the friction force along the ship-ice contact surface upward; v z is the relative velocity of ship-ice along the ship-ice contact surface upward; F fl is the friction force along the ship-ice contact surface horizontally; v l is the relative velocity of ship-ice along the ship-ice contact surface horizontally; V is the total velocity of ship sliding relative to ice;

[0033] S33, the total load of the ship in the parent ship body coordinate system under the flat ice is τ pice :

[0034] where, is the transformation matrix between the local coordinate of the ship-ice contact surface and the ship body coordinate;

[0035] S34, in order to judge the fracture of the flat ice in contact with the ship body and the shape characteristics, the bending failure load P f of the flat ice is calculated, and the ship-ice collision model is calculated as:

[0036] where C f is an empirical parameter; σ f is the bending strength of ice; θ is the opening angle of the ice wedge at the ship-ice contact, and h i is the thickness of the ice layer;

[0037] When the resultant force of the ship-ice compressive force and the friction force in the vertical direction is greater than the bending failure limit load P f , the flat ice is broken and the broken ice is detached;

[0038] S35, the detached broken ice is in the shape of a sector, and the ring crack method is used to express the shape characteristics of the detached broken ice by using the broken radius and the opening angle of the ice wedge at the ship-ice contact. The calculation model of the broken radius R is:

[0039]

[0040] where C l , C v are empirical coefficients, n is the Poisson's ratio, E is the elastic modulus of ice; ρ w is the density of seawater; v nis the relative normal velocity between the waterline discrete points and the flat ice boundary discrete points;

[0041] S36, after determining the broken radius of the shape feature of the broken ice and the opening angle of the ice wedge at the ice-ship contact, the broken ice is broken according to the sea ice distribution released by the coach software, the flat ice boundary is updated, the flat distribution is represented, and the boundary of the broken ice falling from the flat ice is generated.

[0042] Further, a preferred embodiment is provided, in which, in step three, when the ship-ice contact is detected, the ice field module calculates the flat ice breaking, the broken ice movement, and the total load of the flat ice and the broken ice according to the sea ice distribution, the ice layer thickness, and the material properties according to the ship-flat ice collision model and the ship-broken ice collision model.

[0043] S311, first, a dynamic model of each piece of broken ice in the ship navigation area is established:

[0044] wherein, F s is the resultant external force of the wind and wave flow force and the contact force with the flat ice, the broken ice, and the ship body, T s is the resultant external moment; m s is the total mass of the current calculation of the broken ice; J s is the total inertia tensor;

[0045] The values of F s , T s , m s , and J s are input to obtain the broken ice movement velocity vector v s and the angular velocity vector ω s , and the displacement and rotational movement data of each piece of broken ice are integrated to represent the broken ice distribution;

[0046] S322, the contact between the broken ice solid surfaces is calculated using a linear spring damping system, and the contact force calculation model of the ship-broken ice, the broken ice-broken ice, and the broken ice-flat ice near the ship body is: F n =-kd n -ηv n

[0047] wherein, k is the material elastic coefficient of the ice; η is the material damping coefficient of the ice; d n is the normal overlap distance between the ice and other objects, v n is the normal overlap velocity, d t is the tangential overlap distance, v t is the tangential overlap velocity, μ is the friction coefficient; n t is the tangential unit direction of the broken ice boundary; F n is the normal contact force of the ice boundary inwardt The contact force is tangential along the ice boundary;

[0048] S333, The final total load on the mother ship from the ice fragments in the mother ship's body coordinate system is τ. sice :

[0049] This is the transformation matrix between the local coordinates of the ship-ice contact surface and the ship's hull coordinates.

[0050] Furthermore, a preferred embodiment is provided, in step four, the propeller thrust affected by ice is calculated by using the rotational speed and rudder angle provided by the polar ship driving control simulation subsystem as control commands; that is, the propeller thrust T affected by broken ice. P The calculation method is as follows:

[0051] Where: t p To reduce the thrust of the propeller; ρ w n is the density of seawater. p D is the propeller speed; p K is the propeller diameter; T W is the thrust coefficient. p U is the wake velocity; u is the relative velocity between the ship and the ice floes; T is the speed of the wake. P This is for propeller thrust.

[0052] Furthermore, a preferred embodiment is provided, wherein the method for establishing the six-degree-of-freedom motion simulation model of the ship in step four is as follows:

[0053] Where: M0 is the sum of the mother ship's mass and the additional mass; C RB0 For the centripetal force of rigid bodies and fluids, C A0 The Coriolis force matrix; v r0 Let τ be the relative velocity of the mother ship with the ocean current in the body coordinate system; D0 be the damping matrix; K0(t-γ) be the time delay function, where t is the simulation time and γ is the integration variable; U be the longitudinal speed of the mother ship; e1 be the longitudinal unit vector; G0 be the stiffness matrix of the mother ship; τ wind0 For wind load; τ wave0 For wave load; τ P For propeller thrust; τ R For ship rudder force; τ ice The total ice load includes the smoothing ice load τ. pice With ice crushing load τ sice ;

[0054] The polar ship acceleration can be obtained by solving the problem. The ship's motion pose is obtained by integrating the velocity v0 with the fourth-order Runge-Kutta integral.

[0055] Further, a preferred embodiment is provided, and the method for generating a three-dimensional scene by the polar ship navigation visual simulation subsystem according to the sailing sea area and the wind, wave and current environment conditions issued by the instructor software in step five is as follows: the polar ship navigation visual simulation subsystem performs three-dimensional scene simulation based on a three-dimensional engine, the simulation process is driven by the sailing sea area and the wind, wave and current environment conditions issued by the instructor software, the initial position of the ship, the initial distribution of the flat ice and the broken ice are loaded, the three-dimensional engine is driven to perform rendering of the marine environment, the atmospheric environment, the ice area and the ship three-dimensional model, and a three-dimensional scene is generated.

[0056] The present application has the advantages of:

[0057] The present application constructs a ship six-degree-of-freedom motion model for the ice load problem in ship ice area navigation, and compared with the prior art, the ship six-degree-of-freedom motion model constructed by the present application is suitable for the polar environment.

[0058] The present application constructs a thrust calculation model for the problem of the influence of broken ice on the propeller propulsion process, the relative motion speed of the ship and the broken ice is obtained by solving the broken ice motion by taking the broken ice as an independent moving object, the influence of the broken ice on the propeller performance is considered by taking into account the relative speed of the ship and the broken ice in the propeller modeling process, and the influence is applied to the ship six-degree-of-freedom motion response model.

[0059] The ice load calculation of the present application includes the load of flat ice and broken ice, the flat ice breaking shape is determined by using the ring crack method, the simulation result is relatively accurate while the calculation speed is fast, and the generated broken ice is close to the real situation.

[0060] The ship-flat ice contact point detection part of the present application uses a multi-process parallel method to traverse the intersection test of the ship waterline boundary point line segment and the flat ice boundary point line segment, thereby improving the calculation efficiency of the simulation system.

[0061] The present application displays and updates the ice cracks and broken ice after the ice layer is acted on by the icebreaker in real time, the crack shape, size, broken ice shape, motion and distribution are obtained by the ship-flat ice / broken ice collision simulation model calculation, the ice dynamic law after the ship ice interaction is met, and the behavior and environment are highly realistic.

[0062] That is, the present application is also applicable to providing specific simulation navigation training for the crew of the polar navigation. BRIEF DESCRIPTION OF DRAWINGS

[0063] Fig. 1 is a composition schematic diagram of a polar ship navigation simulation system according to the first embodiment.

[0064] Fig. 2 is a flow chart of a polar ship navigation simulation modeling method according to the third embodiment. DETAILED DESCRIPTION

[0065] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application.

[0066] Embodiment one, the embodiment provides a polar ship navigation simulation system, the polar ship navigation simulation system includes integrated management and evaluation subsystem, ship driving control simulation subsystem, polar operation environment simulation subsystem, polar ship real-time motion simulation subsystem and polar ship real-time motion simulation subsystem;

[0067] The integrated management and evaluation subsystem includes a trainer software and an electronic chart software, the trainer software is used for providing polar environment and ice layer distribution input conditions for the polar operation environment simulation subsystem; the electronic chart software is used for providing a ship initial position and a route planning for the polar ship motion simulation subsystem in real time, and simultaneously controlling a simulation process of the simulation system;

[0068] The ship real-time motion simulation subsystem includes a propeller operation module, a rudder operation module, a driving and navigation control module; is used for providing a propeller rotating speed, a rudder angle and a propeller fault control instruction for the polar ship real-time motion simulation subsystem, and is used for simulating ship navigation control;

[0069] The polar operation environment simulation subsystem includes a wind speed module, a wave field module, a flow speed module and an ice field module; and establishes a ship-flat ice collision model and a ship-ice crushing collision model, and calculates polar environment load, ice load, ice crushing and motion data;

[0070] The polar ship real-time motion simulation subsystem includes a propeller module, a rudder module and a ship body module, and calculates ship motion considering wind, wave, flow and ice load influence by establishing a ship six-degree-of-freedom motion simulation model;

[0071] The polar ship navigation visual simulation subsystem receives ice crushing and motion data calculated by the polar operation environment simulation subsystem and ship motion data calculated by the polar ship real-time motion simulation subsystem, and is used for real-time display and update of polar navigation, atmosphere, ocean and ice field scenes.

[0072] Referring to FIG. 1, a polar ship navigation simulation system includes an integrated management and evaluation subsystem, a polar ship driving control simulation subsystem, a polar environment simulation subsystem, a polar ship real-time motion simulation subsystem and a polar ship navigation visual simulation subsystem, each system is based on a TCP / UDP network, uses a publish / subscribe, client / server and other models, and realizes data transmission of multiple communication mechanisms.

[0073] The integrated management and evaluation subsystem, the polar ship driving control simulation subsystem, a reference height, a wind speed, a frequency, a significant wave height, a period, a water depth, a tidal current speed, a flow direction, environmental conditions, sea ice conditions such as sea ice distribution and ice layer thickness, material properties, simulation working condition settings such as a ship initial position and an expected navigation track, and a propeller rotating speed, a rudder angle, and a propeller fault control instruction input function are provided.

[0074] The polar environment simulation subsystem and the polar ship real-time motion simulation subsystem provide wind, wave, current, and ice loads, flat ice breaking, broken ice motion, propeller thrust and rudder force considering the influence of broken ice, and polar ship navigation motion calculation functions considering the influence of wind, wave, current, and ice loads.

[0075] Embodiment two, the polar ship navigation simulation system of embodiment one is further limited, the polar ship navigation visual simulation subsystem includes a polar region ship motion simulation driving module, a sea ice motion simulation driving module, a polar region environment simulation module, and a polar region navigation auxiliary information display module.

[0076] The polar region ship motion simulation driving module is used to receive and update the motion position and posture of the polar region ship in real time.

[0077] The sea ice motion simulation driving module is used to receive and update the floating ice distribution of the ship navigation area in real time.

[0078] The polar region environment simulation module is used to update the polar region environment synchronously according to the instructor's instruction.

[0079] The polar region navigation auxiliary information display module is used to dynamically display the ice layer thickness and the interference distance in the visual scene.

[0080] The polar ship navigation visual simulation subsystem of the embodiment updates the polar ship navigation simulation scene in real time according to the ship position and posture calculated by the polar ship real-time motion simulation subsystem, assists the driver in judging the ship ice navigation state, and divides the polar three-dimensional scene into two sea ice driving modes of flat ice area icebreaking navigation and broken ice area navigation. The ice surface cracks and broken ice motion calculated according to the ship-ice collision simulation model are used to update the flat ice and broken ice distribution in the navigation area during the flat ice area icebreaking navigation simulation. The floating ice geometry in the channel is randomly generated during the broken ice area navigation simulation. The floating ice position is updated according to the broken ice motion data. And according to the navigation sea area environmental conditions published by the integrated management and evaluation subsystem, the lighting, ice and snow, and wave effects are simulated.

[0081] Embodiment three, the polar ship navigation simulation modeling method is proposed, the system of any one of embodiments one to two is used to realize the polar ship navigation simulation modeling method, and the polar ship navigation simulation modeling method includes the following steps:

[0082] Step one, through the comprehensive management and evaluation of the trainer software and electronic chart software of the subsystem, the environmental conditions, sea ice conditions, initial position of the ship and expected track are set, and the simulation task is issued;

[0083] Step two, according to the simulation task issued in step one, the polar environment simulation subsystem calculates the wind, wave and flow load according to the set environmental conditions through the wind speed module, wave field module and flow speed module, and uses the multi-thread parallel programming method to traverse the ship waterline surface boundary point and the nearby flat ice and broken ice boundary point to detect the ship-ice contact condition.

[0084] Step three, based on the detection of the ship-ice contact condition in step two, when the ship-ice contact is detected, the ice field module calculates the flat ice breaking, broken ice movement and total load of flat ice and broken ice according to the sea ice distribution, ice thickness and material properties under the conditions of ship-flat ice collision model and ship-broken ice collision model.

[0085] Step four, the polar ship real-time motion simulation subsystem inputs the wind load, wave load, relative speed of ship and sea current, total load of flat ice and total load of broken ice calculated by the polar environment simulation subsystem as environmental load, and inputs the rotation speed and rudder angle provided by the polar ship driving control simulation subsystem as control instruction, to respectively establish the propeller model, rudder model and polar ship six-degree-of-freedom motion simulation model.

[0086] Step five, the polar ship navigation visual simulation subsystem generates a three-dimensional scene according to the navigation sea area and wind, wave and flow environmental conditions issued by the trainer software, updates the flat ice and broken ice distribution according to the flat ice breaking feature data and broken ice movement data calculated by the polar environment simulation subsystem, and updates the polar ship navigation simulation three-dimensional scene according to the ship navigation motion data calculated by the polar ship real-time motion simulation subsystem.

[0087] Embodiment four, the embodiment is a further limitation of the polar ship navigation simulation modeling method of embodiment three, and step three further includes the steps of respectively calculating the ship-ice contact area, the extrusion force and friction force between the ship and the ice, and the flat ice bending damage load, judging the flat ice breaking condition, and representing the shape characteristics of the broken ice by the radius of the broken ice and the opening angle of the ice wedge.

[0088] Embodiment five, the embodiment is a further limitation of the polar ship navigation simulation modeling method of embodiment four, and the steps of calculating the ship-ice contact area, the extrusion force and friction force between the ship and the ice, and the flat ice bending damage load, judging the flat ice breaking condition, and representing the shape characteristics of the broken ice by the radius of the broken ice and the opening angle of the ice wedge in step three specifically include the following steps:

[0089] S31, first, the ice thickness hi , the angle between the ship's outer normal at the ship-ice contact and the downward vertical axis and the extrusion depth L d , judging the shape of the ship-ice contact and calculating the contact area A between the ship and the flat ice c , the calculation model of the ship-flat ice collision is:

[0090] wherein, L h is the length of the ship boundary in contact with the ice boundary on the horizontal ice surface; L d is the depth of the extrusion of the ship into the ice boundary on the horizontal ice surface; is the angle between the ship's outer normal at the ship-ice contact and the downward vertical axis; h i is the thickness of the ice layer;

[0091] S32, secondly, the extrusion force F c and the friction force F c between the ship and the ice are calculated respectively through the contact area A between the ship and the flat ice f , the calculation model of the ship-flat ice collision is: F c = n c ·σ c A c F fz =-τ c ·μ f F c v z / V F fl =-τ c ·μ f F c v l / V

[0092] wherein, n c is the unit normal of the ship-ice contact surface; σ c is the extrusion strength of the ice; τ c is the unit tangent of the ship-ice contact surface; μ f is the friction coefficient between the ship and the ice; F fz is the upward friction force along the ship-ice contact surface; v z is the relative speed of the ship and the ice along the ship-ice contact surface; F fl is the horizontal friction force along the ship-ice contact surface; v l is the relative speed of the ship and the ice along the horizontal direction of the ship-ice contact surface; V is the total speed of the ship relative to the ice slip;

[0093] S33, finally, the total load τ pice on the ship relative to the flat ice in the ship coordinate system is obtained.

[0094] wherein, A transformation matrix between the local coordinate of the ice-ship contact surface and the ship coordinate;

[0095] S34, in order to determine the flat ice fracture and shape characteristics of the contact with the ship, the flat ice bending failure load P is calculated f The ship-ice collision model is calculated as:

[0096] Wherein, C f is an empirical parameter; σ f is the bending strength of the ice; θ is the opening angle of the ice wedge at the ice-ship contact, h i is the ice thickness;

[0097] When the combined force of the ice-ship extrusion force and the friction force in the vertical direction is greater than the bending failure limit load P f , the flat ice is broken and the broken ice is detached;

[0098] S35, the detached broken ice is in the shape of a fan, and the ring crack method is used to express the shape characteristics of the detached broken ice by using the broken radius and the opening angle of the ice wedge at the ice-ship contact. The broken radius R calculation model is:

[0099] Wherein, C l , C v are empirical coefficients, n is the Poisson's ratio, E is the ice elastic modulus; ρ w is the seawater density; v n is the relative normal velocity between the waterline discrete point and the flat ice boundary discrete point;

[0100] S36, after determining the broken radius and the opening angle of the ice wedge at the ice-ship contact, the broken ice is broken according to the sea ice distribution released by the coach software, the flat ice boundary is updated to express the flat distribution, and the boundary of the broken ice detached from the flat ice is generated.

[0101] Embodiment six, this embodiment is a further limitation of the polar ship navigation simulation modeling method of embodiment three. In step three, when the ice-ship contact is detected, the ice field module calculates the flat ice breaking, the broken ice movement, and the total load of the flat ice and the broken ice according to the sea ice distribution, the ice thickness, and the material properties according to the ship-flat ice collision model and the ship-broken ice collision model.

[0102] S311, first, the dynamic model of each piece of broken ice in the ship navigation area is established:

[0103] Wherein, F s is the combined external force of the wind and wave flow force and the contact force with the flat ice, the broken ice, and the ship, T sis the total moment of external forces; m s is the total mass of the ice; J s is the total inertia tensor;

[0104] input values of F s , T s , m s and J s to obtain the ice motion velocity vector v s ; the angular velocity vector ω s , and integrate to obtain the displacement and rotational motion data of each piece of ice, indicating the ice distribution;

[0105] S322, the contact between the ice solids is calculated using a linear spring damping system, and the contact force calculation model of the ship-ice, ice-ice, and ice-flat ice near the ship body is: F n = -kd n -ηv n

[0106] where k is the material elastic coefficient of ice; η is the material damping coefficient of ice; d n is the normal overlap distance between ice and other objects, v n is the normal overlap velocity, d t is the tangential overlap distance, v t is the tangential overlap velocity, and μ is the friction coefficient; n t is the tangential unit direction of the ice boundary; F n is the normal contact force inward along the ice boundary, and F t is the tangential contact force along the ice boundary;

[0107] S333, the total load of the ship under the ice in the ship body coordinate system is finally obtained as τ sice :

[0108] is the transformation matrix between the local coordinate of the ship-ice contact surface and the ship body coordinate.

[0109] Embodiment seven, this embodiment is a further limitation of the polar ship navigation simulation modeling method of embodiment three, in step four, the step of calculating the ice-affected propeller thrust by taking the rotation speed and rudder angle provided by the polar ship driving control simulation subsystem as control instructions; that is, the ice-affected propeller thrust T P is calculated as follows:

[0110] where t p is the propeller thrust deduction; ρ w is the seawater density; n p is the propeller rotation speed; and Dp D is the diameter of the propeller; K T C is the thrust coefficient; W p u is the relative velocity between the ship and the ice; T P is the propeller thrust.

[0111] Embodiment eight, the embodiment is further limited to the polar ship navigation simulation modeling method described in embodiment three, the method for establishing the ship six-degree-of-freedom motion simulation model in step four is:

[0112] Wherein: M0 is the sum of the mass of the mother ship and the added mass; C RB0 is the centripetal force of the rigid body and the fluid, C A0 is the Coriolis force matrix; v r0 is the relative velocity of the mother ship with respect to the current in the body coordinate system; D0 is the damping matrix; K0(t-γ) is a time delay function, wherein t is the simulation time, and γ is the integral variable; U is the longitudinal speed of the mother ship; e1 is a longitudinal unit vector; G0 is the stiffness matrix of the mother ship; τ wind0 is the wind load; τ wave0 is the wave load; τ P is the propeller thrust; τ R is the ship rudder force; τ ice is the total ice load, including the flat ice load τ pice and the broken ice load τ sice ;

[0113] The polar ship navigation acceleration a0 is solved and the speed v0, and the ship motion pose is obtained by fourth-order Runge-Kutta integration.

[0114] Embodiment nine, the embodiment is further limited to the polar ship navigation simulation modeling method described in embodiment three, the method for generating a three-dimensional scene by the polar ship navigation visual simulation subsystem according to the navigation sea area and the wind, wave and current environmental conditions published by the instructor software in step five is: the polar ship navigation visual simulation subsystem simulates a three-dimensional scene based on a three-dimensional engine, the simulation process loads the initial position of the ship, the initial distribution of the flat ice and the broken ice, and drives the three-dimensional engine to render the marine environment, the atmospheric environment, the ice area and the ship three-dimensional model, and generates a three-dimensional scene through the navigation sea area and the wind, wave and current environmental conditions published by the instructor software.

[0115] Embodiment ten, referring to FIG. 2, the embodiment provides the following examples for explaining embodiments three to nine, and the specific implementation process is:

[0116] To verify the effectiveness and effect of the method described in the embodiment, taking the case of a sea area with only flat ice in the initial sailing simulation of a ship as an example, an instance of a polar ship sailing simulation system and modeling method includes the following steps:

[0117] Step one: start the integrated management and evaluation subsystem, set the sailing sea area reference height, wind speed, frequency, significant wave height, period, water depth, tidal current speed, flow direction environmental conditions, and sea ice conditions such as flat ice distribution, ice layer thickness, ice elastic modulus, and seawater density through the instructor software, set the initial position and expected sailing trajectory of the ship through the electronic chart software, and issue the simulation task;

[0118] Step two: the polar environment simulation subsystem performs the following steps according to the current environmental conditions and sea ice conditions:

[0119] S21, the wind speed module generates a wind spectrum according to the sailing sea area reference height, one-hour average wind speed at the reference height, and frequency published by the instructor software, calculates the wind speed distribution time history, and calculates the wind load using the wind load coefficient at the water surface height;

[0120] S22, the wave field module generates a wave spectrum and a direction spectrum according to the significant wave height, characteristic period, and direction spread function published by the instructor software, calculates the wave elevation time history, and calculates the wave load using the response amplitude operator;

[0121] S23, the flow speed module calculates the wind speed induced flow speed component according to the wind speed and sea conditions, calculates the flow speed distribution time history according to the water depth and tidal current speed published by the instructor software, and obtains the relative speed of the ship and the current;

[0122] S24, the ship's waterline surface is discretized into boundary points, and a multi-thread parallel programming method is used to traverse the ship's waterline surface boundary points and nearby flat ice boundary points. If there are ice boundary points inside the ship's waterline surface boundary, it indicates that the ship and the ice are in contact;

[0123] Step three: when the ship-ice collision is detected, the ice field module of the polar environment simulation subsystem calculates the flat ice crushing, the movement of the detached ice, and the total load of the flat ice and the detached ice according to the sea ice conditions such as the flat ice distribution, ice layer thickness, ice elastic modulus, and seawater density published by the instructor software, according to the ship-flat ice collision:

[0124] The ice field module establishes a ship-flat ice collision simulation model, calculates the ship-ice contact area, the extrusion force and friction between the ship and the ice, and the flat ice bending damage load in steps, judges the flat ice crushing, and represents the shape characteristics of the detached ice after the flat ice breaks through the radius of the detached ice and the opening angle of the ice wedge, which specifically includes the following steps:

[0125] S31, first, the ice layer thickness h i, the angle between the ship's outer normal at the ship-ice contact and the downward vertical axis and the extrusion depth L d , judging the shape of the ship-ice contact, and calculating the contact area A of the ship with the flat ice c , the calculation model is as follows:

[0126] The input conditions of the model include: L h , the length of the ship boundary in contact with the ice boundary on the horizontal ice surface; L d , the depth of the extrusion of the ship into the ice boundary on the horizontal ice surface; , the angle between the ship's outer normal at the ship-ice contact and the downward vertical axis; h i , the thickness of the ice layer;

[0127] S32, the contact area A c is calculated again, and the extrusion force F c and the friction force F f between the ship and the ice are calculated respectively, and the calculation model is as follows: F c = n c ·σ c A c F fz =-τ c ·μ f F c v z / V F fl =-τ c ·μ f F c v l / V

[0128] The input conditions include: n c , the unit normal of the ship-ice contact surface; σ c , the extrusion strength of the ice; τ c , the unit tangent of the ship-ice contact surface; μ f , the friction coefficient between the ship and the ice; F fz , the friction force in the upward direction along the ship-ice contact surface; v z , the relative speed of the ship and the ice in the upward direction along the ship-ice contact surface; F fl , the friction force in the horizontal direction along the ship-ice contact surface; v l , the relative speed of the ship and the ice in the horizontal direction along the ship-ice contact surface; V, the total speed of the ship relative to the ice slip;

[0129] S33, the total load of the ship on the flat ice in the body coordinate system of the mother ship is finally obtained as τ pice :

[0130] The input conditions include: F c , the extrusion force; F fz and Ffl Friction force; is the transformation matrix between local coordinate and hull coordinate of ice-ship contact surface;

[0131] S34, in order to determine the flat ice fracture and shape characteristics of the ice-ship contact, the flat ice bending failure load P is calculated f The calculation model is:

[0132] The input conditions include: f is an empirical parameter; σ f is the bending strength of ice; θ is the opening angle of the ice wedge at the ice-ship contact, h i is the thickness of the ice layer;

[0133] When the resultant force of the ice-ship extrusion force and the friction force in the vertical direction is greater than the bending failure limit load P f , the flat ice breaks and the broken ice falls off;

[0134] S35, the shape of the broken ice is a fan shape, and the ring crack method is used to express the shape characteristics of the broken ice, the broken radius R is calculated by the broken radius and the opening angle of the ice wedge at the ice-ship contact, and the calculation model is:

[0135] The input conditions of the model include: l , C v is an empirical coefficient, n is the Poisson's ratio, E is the elastic modulus of ice; ρ w is the density of seawater; v n is the relative normal velocity between the waterline discrete points and the flat ice boundary discrete points;

[0136] S36, after determining the shape characteristics (broken radius and opening angle of the ice wedge at the ice-ship contact) of the broken ice, the broken ice is fractured according to the sea ice distribution released by the coach software, the flat ice boundary is updated to express the flat distribution, and the boundary of the broken ice falling off from the flat ice is generated; in the calculation process of the opening angle of the ice wedge at the ice-ship contact, firstly, the contact points of the waterline of the current position of the ship and the two ends of the flat ice boundary are obtained by traversal, if the distance between the contact point and the discrete i-th flat ice boundary point is less than the broken radius, and the distance between the continuous i+1-th flat ice boundary point is greater than the broken radius, then the fracture point is located between the continuous flat ice boundary points, and the distance between the fracture point and the contact point is equal to the broken radius, the linear interpolation method can be used to determine the two end fracture points of the ring crack of the flat ice; then the intersection point of the median line of the two end fracture points and the ice boundary is determined to be the vertex of the ice wedge at the ice-ship contact, and the opening angle of the ice wedge at the ice-ship contact is solved by the inverse trigonometric function.

[0137] After the flat ice breaks into pieces, the pieces move as independent objects. When the ship collides with the pieces, a ship-piece collision simulation model is established by using the ice field module to calculate the solid surface contact forces between the ship and the pieces, the pieces and the pieces, and the pieces and the flat ice in steps, calculate the movement of each independent piece in the ship navigation area under the influence of wind, wave, flow and collision, and specifically include the following steps:

[0138] S311, first, a dynamic model of each piece of ice in the ship navigation area is established:

[0139] The model input conditions include: F s is the total external force on the piece of ice caused by the wind, wave and flow forces and the contact forces between the piece of ice, the flat ice and the ship body, T s is the total external torque; m s is the total mass of the current calculation piece of ice; J s is the total inertia tensor;

[0140] The values of F s , T s , m s and J s are input to obtain the movement speed vector v s and the angular velocity vector ω s of the piece of ice, and the displacement and rotational movement data of each piece of ice are integrated to represent the distribution of the piece of ice;

[0141] S322, the contact between the pieces of ice is calculated by using a linear spring damping system, and the contact force calculation model of the ship-piece, piece-piece and piece-flat ice near the ship body is: F n =-kd n -ηv n

[0142] The model input conditions include: k is the material elastic coefficient of the ice; η is the material damping coefficient of the ice; d n is the normal overlap distance between the ice and other objects, v n is the normal overlap speed, d t is the tangential overlap distance, v t is the tangential overlap speed, μ is the friction coefficient; n t is the tangential unit direction of the piece of ice boundary; F n is the normal contact force of the ice boundary inward, and F t is the tangential contact force along the ice boundary;

[0143] S333, finally, the total load τ sice on the ship in the ship body coordinate system is obtained:

[0144] is a transformation matrix between the local coordinate of the ice contact surface of the ship and the ship coordinate.

[0145] Step four: the polar ship driving control simulation subsystem configures the ship propeller fault condition through the driving and navigation control module according to the navigation task issued by the instructor software, provides the rotation speed and rudder angle control instruction for the propeller module and rudder module of the polar ship real-time motion simulation subsystem through the operation of the propeller simulation control handle and the rudder simulation control handle, and makes the ship sail in different directions;

[0146] Step five: the polar ship real-time motion simulation subsystem takes the wind load, wave load, relative velocity between the ship and the current calculated by the polar environment simulation subsystem at S21 to S23, the total load of the flat ice calculated by S313, and the total load of the broken ice calculated by S333 as the environmental load input, and takes the rotation speed and rudder angle provided by the polar ship driving control simulation subsystem as the control instruction input, step by step to establish the propeller model, rudder model and polar region ship six-degree-of-freedom motion simulation model, calculate the polar region ship navigation motion data considering the influence of wind, wave, current and ice load, which specifically includes the following steps:

[0147] S51, the propeller module calculates the propeller thrust considering the influence of ice according to the propeller rotation speed instruction provided by the polar ship driving control simulation subsystem by establishing the ship propeller model, taking into account the relative velocity between the ship and the broken ice, and considering the influence of broken ice on the propeller performance; the propeller thrust calculation model affected by broken ice:

[0148] The model input conditions include: t p is the propeller thrust deduction; p w is the seawater density; n p is the propeller rotation speed; D p is the propeller diameter; K T is the thrust coefficient; W p is the wake velocity; u is the relative velocity between the ship and the broken ice; T P is the propeller thrust.

[0149] S52, the rudder module calculates the ship rudder force according to the rudder angle control instruction provided by the polar ship driving control simulation subsystem by establishing the rudder model, taking into account the flow velocity at the rudder, considering the influence of the current on the rudder effect, and controlling the ship sailing direction; the rudder model:

[0150] The model input conditions include: C L is the lift coefficient of the rudder; C D is the drag coefficient of the rudder; L is the aspect ratio of the rudder; d is the rudder angle; R n is the Reynolds number of the rudder; C Qis the prismatic coefficient, about 1 when the rudder upper and lower edges are sharp; v f is the flow velocity at the rudder, taken as 1.25 times the ship speed; p w is the seawater density; A r is the rudder area; x r is the distance from the rudder to the midship plane, negative for a stern rudder;

[0151] The model calculation results are: the rudder forces X R ,N R ,Y R in the longitudinal, transverse and vertical directions of the coordinate system;

[0152] S53, the hull module, by establishing a polar region ship six-degree-of-freedom motion simulation model, taking into account the wind load, wave load and the relative velocity of the ship and the current, considering the influence of wind, wave and current environmental conditions on the ship motion, taking into account the total load of flat ice and the total load of broken ice, considering the influence of ice on the ship motion, taking into account the propeller thrust and the ship rudder force to control the ship navigation state, and through integral calculation, the six-degree-of-freedom motion data of the ship is obtained;

[0153] According to the parent ship lines, the hydrodynamic coefficients and time delay functions of the parent ship are calculated, and a six-degree-of-freedom motion simulation model of the ship is established according to the ice conditions and ocean state in the broken ice area:

[0154] The model input conditions include: M0 is the sum of the mass and additional mass of the parent ship; C RB0 is the centripetal force of the rigid body and fluid, C A0 is the Coriolis force matrix; v r0 is the relative velocity of the parent ship with the current in the body coordinate system; D0 is the damping matrix; K0(t-γ) is the time delay function, wherein t is the simulation time, and γ is the integral variable; U is the longitudinal speed of the parent ship; e1 is the longitudinal unit vector; G0 is the stiffness matrix of the parent ship; τ wind0 is the wind load; τ wave0 is the wave load; τ P is the propeller thrust; τ R is the ship rudder force; τ ice is the total ice load, including flat ice load τ pice and broken ice load τ sice ;

[0155] The polar region ship navigation acceleration and the speed v0 are obtained by solving, and the ship motion position and posture are obtained by four-order Runge-Kutta integral.

[0156] Step Six: The polar vessel navigation visual simulation subsystem simulates a 3D scene based on the Unreal Engine. During the simulation, the navigation sea area and wind, wave and current environmental conditions released by the instructor software are used to load the initial position of the ship and the initial distribution of flat ice and broken ice. The 3D engine is then used to render the marine environment, atmospheric environment, ice zone and ship 3D model to generate a 3D scene. The flat ice boundary and shape in the 3D scene are updated according to the flat ice breaking characteristic data (breaking radius and opening angle of ice wedge at the ship-ice contact point) calculated in Step Three. The distribution of broken ice in the 3D scene is updated according to the broken ice motion data (displacement and rotation of each independent broken ice piece). The ship's navigation posture in the 3D scene is updated according to the ship motion posture data calculated in Step Five.

[0157] Any process or method description in the flowcharts shown in Figures 1 and 2, or otherwise described herein, can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing a custom logical function or process. The scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functionality involved, as will be understood by those skilled in the art to which embodiments of the invention pertain. The logic and / or steps shown in the flowcharts or otherwise described herein illustrate the architecture, functionality, and operation of possible implementations of apparatuses and methods according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those shown in the figures. For example, two consecutively shown blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functionality involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions. For example, a sequence of executable instructions that can be considered as implementing logical functions can be embodied in any computer-readable medium for use by instruction execution systems, apparatus, or devices (such as computer-based systems, processor-based systems, or other systems that can fetch and execute instructions from instruction execution systems, apparatus, or devices), or in conjunction with such instruction execution systems, apparatus, or devices.

[0158] Those skilled in the art can understand that the above description is only the preferred embodiment of the present application, and the features described in various embodiments of the present disclosure and / or claims can be combined or combined, even if such combination or combination is not explicitly described in the present disclosure. It is not intended to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacement for part of the technical features, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0159] Although preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application. Obviously, those skilled in the art can make various modifications and changes to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and changes of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and changes.

Claims

1. A polar ship navigation simulation system, characterized in that, The polar ship navigation simulation system comprises a comprehensive management and evaluation subsystem, a ship driving control simulation subsystem, a polar operation environment simulation subsystem, a polar ship real-time motion simulation subsystem and a polar ship real-time motion simulation subsystem; The comprehensive management and evaluation subsystem comprises a trainer software and an electronic chart software, the trainer software is used for providing polar environment and ice layer distribution input conditions for the polar operation environment simulation subsystem; the electronic chart software is used for providing a ship initial position and a route planning for the polar ship motion simulation subsystem in real time, and simultaneously controlling a simulation process of the simulation system; The ship real-time motion simulation subsystem comprises a propeller operation module, a rudder operation module and a driving and navigation control module; The polar ship real-time motion simulation subsystem is used for providing a propeller rotating speed, a rudder angle and a propeller fault control instruction, and is used for simulating ship navigation control; The polar operation environment simulation subsystem comprises a wind speed module, a wave field module, a flow speed module and an ice field module; a ship-flat ice collision model and a ship-ice collision model are established, and polar environment load, ice load, ice breaking and motion data are calculated; The polar ship real-time motion simulation subsystem comprises a propeller module, a rudder module and a ship body module; a ship six-degree-of-freedom motion simulation model is established, and ship motion considering wind, wave, flow and ice load is calculated; The polar ship navigation visual simulation subsystem receives ice breaking and motion data calculated by the polar operation environment simulation subsystem and ship motion data calculated by the polar ship real-time motion simulation subsystem, and is used for real-time display and update of polar navigation, atmosphere, ocean and ice field scenes.

2. The polar ship navigation simulation system according to claim 1, characterized in that, The polar ship navigation visual simulation subsystem comprises a polar region ship motion simulation driving module, a sea ice motion simulation driving module, a polar region environment simulation module and a polar region navigation auxiliary information display module; The polar region ship motion simulation driving module is used for real-time receiving and updating a motion position of the polar region ship during navigation; The sea ice motion simulation driving module is used for real-time receiving and updating a floating ice distribution of a ship navigation area; The polar region environment simulation module is used for synchronously updating a polar region environment according to a trainer instruction; The polar region navigation auxiliary information display module is used for dynamically displaying ice layer thickness and interference distance in the visual scene.

3. A polar ship navigation simulation modeling method, characterized by, The polar ship navigation simulation modeling method is realized by using the system in any one of claims 1 to 2, and comprises the following steps: Step one, environment conditions, sea ice conditions, a ship initial position and an expected navigation track are set by using the trainer software and the electronic chart software of the comprehensive management and evaluation subsystem, and a simulation task is issued; Step two, according to the simulation task issued in step one, the polar environment simulation subsystem calculates wind, wave and flow load by using a wind speed module, a wave field module and a flow speed module according to the set environment conditions, and a multi-thread parallel programming method is used to traverse ship waterline surface boundary points and nearby flat ice and ice boundary points, and a ship-ice contact condition is detected; Step three, based on the detection of the ship ice contact situation described in step two, wherein when the ship ice contact is detected, the ice field module calculates the flat ice breaking, ice movement, and total load of flat ice and broken ice according to the sea ice distribution, ice thickness, material properties, and two cases of ship-flat ice collision model and ship-broken ice collision model; Step four, the polar ship real-time motion simulation subsystem inputs the wind load, wave load, relative speed of the ship and the current, total load of flat ice, and total load of broken ice calculated by the polar environment simulation subsystem as environmental load, and inputs the rotation speed and rudder angle provided by the polar ship driving control simulation subsystem as control instruction, to respectively establish the propeller model, rudder model, and polar ship six-degree-of-freedom motion simulation model. Step five, the polar ship navigation visual simulation subsystem generates a three-dimensional scene according to the navigation sea area and wind and wave flow environmental conditions issued by the instructor software, updates the flat ice and broken ice distribution according to the flat ice breaking feature data and broken ice movement data calculated by the polar environment simulation subsystem, and updates the polar ship navigation simulation three-dimensional scene according to the ship navigation motion data calculated by the polar ship real-time motion simulation subsystem.

4. The polar ship navigation simulation modeling method according to claim 3, characterized in that, The step three further includes the steps of respectively calculating the ship-ice contact area, the extrusion force and friction between the ship and the ice, and the flat ice bending damage load, judging the flat ice breaking condition, and representing the shape feature of the broken ice by the broken ice radius and the opening angle of the ice wedge.

5. A polar ship navigation simulation modeling method according to claim 4, characterized in that, The step three of calculating the ship-ice contact area, the extrusion force and friction between the ship and the ice, and the flat ice bending damage load, judging the flat ice breaking condition, and representing the shape feature of the broken ice by the broken ice radius and the opening angle of the ice wedge specifically includes the following steps: S31, first pass ice layer thickness h i angle between the ship's outer normal at the ice contact and the downward vertical axis and the extrusion depth L d , judging the shape of the ice-ship contact, calculating the contact area A of the ship and the flat ice c , calculating the ship-flat ice collision model as: where L h is the length of the ship boundary in contact with the ice boundary on the horizontal ice surface; L d is the depth of the ship pressed into the ice boundary on the horizontal ice surface; is the angle between the ship's outer normal at the ice contact and the downward vertical axis; h i is the ice layer thickness; S32, secondly, the contact area A between the ship and the flat ice c The squeezing force F between the ship and the ice is calculated c And the friction force F f The ship-flat ice collision model is calculated as follows: F c = n c · σ c A c F fz = -τ c ·μ f F c v z / V F fl = -τ c ·μ f F c v l / V where n c is the unit normal to the ship-ice contact surface; σ c is the compressive strength of the ice; τ c is the unit tangent to the ship-ice contact surface; μ f is the ship-ice friction coefficient; F fz is the friction force along the ship-ice contact surface in the upward direction; v z is the relative ship-ice velocity along the ship-ice contact surface in the upward direction; F fl is the friction force along the ship-ice contact surface in the horizontal direction; v l is the relative ship-ice velocity along the ship-ice contact surface in the horizontal direction; V is the total ship velocity relative to the ice slip. S33, the total load of the ship under the flat ice in the mother ship body coordinate system is τ pice : wherein, The transformation matrix between the local coordinates of the ship-ice contact surface and the ship body coordinates; S34, to judge the flat ice fracture case and shape feature of the collision contact with the ship body, the flat ice bending failure load P is calculated f The ship-ice collision model is calculated as: where C f is an empirical parameter; σ f is the ice bending strength; θ is the opening angle of the ice wedge at the ship ice contact, h i is the ice layer thickness; When the ship ice pressing force and the friction force in the vertical direction greater than the bending failure limit load P f When the flat ice breaks, the broken ice falls off. S35, the shape of the falling ice is fan-shaped, the shape characteristics of the falling ice are represented by the breaking radius and the opening angle of the ice wedge at the contact between the ship and the ice, and the calculation model of the breaking radius R is: where C l , C v are empirical coefficients, n is the Poisson ratio, E is the ice elastic modulus; p w is the sea water density; v n is the relative normal velocity between the waterline discrete point and the flat ice boundary discrete point; S36, after determining the broken ice shape feature breaking radius and the opening angle of the ice wedge at the ship-ice contact, the flat ice boundary is updated to represent the flat distribution condition according to the sea ice distribution issued by the instructor software, and the boundary of the broken ice falling from the flat ice is generated.

6. The polar ship navigation simulation modeling method according to claim 3, characterized in that, The method of step three of calculating the flat ice breaking, ice movement, and total load of flat ice and broken ice according to the sea ice distribution, ice thickness, material properties, and two cases of ship-flat ice collision model and ship-broken ice collision model when the ship ice contact is detected is as follows: S311、First, the dynamics model of each piece of ice in the ship navigation area is established: where F s is the resultant external force on the rubble ice due to the wave and current forces and the contact forces with the flat ice, rubble ice, and ship hull, T s is the resultant external moment; m s is the current total mass of the rubble ice; J s is the total inertia tensor; Input F s , T s , m s and J s , the value of the ice movement velocity vector v s ; angular velocity vector ω s , integration of each piece of ice displacement and rotation movement data, indicating the ice distribution; S322, the contact between the broken ice solid surfaces is calculated by using a linear spring damping system, and the contact force calculation model of the ship-broken ice, broken ice-broken ice, and broken ice-flat ice near the ship body is as follows: F n = -kd n -ηv n where k is the material elastic coefficient of ice; η is the material damping coefficient of ice; d n is the normal overlap distance between ice and other objects, v n is the normal overlap velocity, d t is the tangential overlap distance, v t is the tangential overlap velocity, μ is the friction coefficient; n t is the tangential unit direction of the ice boundary; F n is the normal contact force of the ice boundary inward, and F t is the tangential contact force along the ice boundary S333、Finally, the total load of the ship under the ice body coordinate system is τ sice : The transformation matrix between the local coordinates of the ship-ice contact surface and the ship body coordinates.

7. The polar ship navigation simulation modeling method according to claim 3, characterized in that, The step of calculating the ice-affected propeller thrust T in step four by taking the rotational speed and the rudder angle provided by the polar ship handling control simulation subsystem as control commands; i.e. the propeller thrust T affected by the ice P The calculation method is: where: t p is the reduction of the propeller thrust; p w is the seawater density; n p is the propeller rotation speed; D p is the propeller diameter; K T is the thrust coefficient; W p is the wake velocity; u is the relative speed of the ship and the ice; T P is the propeller thrust.

8. The polar ship navigation simulation modeling method according to claim 3, characterized in that, The method for establishing the ship six-degree-of-freedom motion simulation model in step four is: where: M0is the sum of the mother ship mass and added mass; C RB0 is the centripetal force of the rigid body and fluid, C A0 is the Coriolis force matrix; v r0 is the relative velocity of the mother ship to the current in the body-fixed coordinate system; D0is the damping matrix; K0(t-γ) is the time delay function, where t is the simulation time and γ is the integration variable; U is the longitudinal speed of the mother ship; e1is the longitudinal unit vector; G0is the stiffness matrix of the mother ship; τ wind0 is the wind load; τ wave0 is the wave load; τ P is the propeller thrust; τ R is the ship rudder force; τ ice is the total ice load, including the flat ice load τ pice and the broken ice load τ sice ; Solving for the polar ship sailing acceleration And the velocity v0, the ship motion pose is obtained by fourth-order Runge-Kutta integration.

9. The polar ship navigation simulation modeling method according to claim 3, characterized in that, The method for generating a three-dimensional scene according to the sailing sea area and the wind, wave and current environment conditions published by the instructor software in step five is as follows: the polar ship sailing visual simulation subsystem simulates a three-dimensional scene based on a three-dimensional engine, the simulation process loads the initial position of the ship, the initial distribution of the flat ice and the broken ice, and drives the three-dimensional engine to render the marine environment, the atmospheric environment, the ice area and the three-dimensional model of the ship, so as to generate a three-dimensional scene.

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