Three-dimensional sea wave and ship traveling wave visual simulation superposition method

Abstract

The invention discloses a three-dimensional sea wave and ship traveling wave visual simulation superposition method, which comprises the following steps of: establishing a ship traveling wave wake model under a Unity engine, and generating wave height and normal data of a ship traveling wave wake according to a Kelvin ship traveling wave formula; preprocessing the data of the ship traveling wave wake model and generating a vector diagram, and optimizing the wave height and normal data of the ship traveling wave wake according to the Kelvin arm and the real ship traveling wave phenomenon; a ship traveling wave wake and a three-dimensional sea wave are superposed based on a ship analog simulation system, a ship traveling wave following effect during ship traveling is added according to the motion condition of a ship, the method is combined with a Unity engine, ship traveling wave simulation has high interactivity, flexibility and expandability, and the method is suitable for large-scale popularization and application. And the problems of difficult simulation and false simulation in the traditional sea wave effect simulation can be effectively solved. Technical guarantee is provided for theoretical research of ship waves, analysis of wave-making resistance of ships, ship design, construction of overwater engineering and the like, and the method has very important research value and popularization significance.

Description

Technical Field

[0001] The invention relates to a ship navigation visual simulation technology, and in particular to a three-dimensional sea wave and ship travel wave visual simulation superposition method. Background Art

[0002] Visual simulation is a computational simulation technology that makes full use of human visual characteristics to achieve highly realistic effects. It focuses on creating a real three-dimensional graphic environment to reflect the changes and interactions between entities. In the development of ship navigation simulation technology in recent years, the simulation of independent motion of ships is relatively complete, while the simulation of waves and the interaction between ships and waves is more difficult and involves multiple knowledge fields. When a ship sails on the sea surface, the interaction between the ship and the seawater produces surface water waves formed by pressure changes, which are called ship waves. Ship waves can usually be divided into bow waves and stern waves according to the different locations where they are generated. Ship waves are extremely complex surface fluctuations. The formation of ship waves is closely related to factors such as the speed, shape, displacement and characteristics of the water body of the ship. It not only affects the navigation performance of the ship, but also affects the surrounding environment and other ships. People have been studying ship waves for more than a century. Among them, the pressure point wave theory proposed by Irish mathematician and physicist Lord Kelvin regards ships as pressure points. Ship waves are waves generated by pressure point sources through uniform motion. They are superpositions of waves in different directions, which are equivalent to the concept of wave groups. Initially, the purpose of studying ship waves was to reduce the resistance of ships. The more obvious the ship waves are, the more energy the ship consumes and the greater the resistance the ship encounters. Nowadays, with the gradual improvement of observation technology, people have further studied the characteristics of ship waves, and can identify the characteristics of ships through the characteristics of ship waves. Therefore, in ship simulation, ship wave simulation is an indispensable part.

[0003] When using the Unity engine to construct a ship simulation experiment, people often face the problem of how to simulate ship waves realistically. For the effect of simulating ship waves, most people currently use particle systems or simple foam maps for simulation. Although the simulated ship waves can meet the basic visual needs of users, the simulated ship waves in these ways often lack realism. In order to improve the authenticity of ship wave simulation in the simulation system, we can introduce sea waves and ship wave formulas. These formulas are based on fluid dynamics and wave theory, and can accurately calculate factors such as the shape, speed and direction of sea waves and ship waves. Through these formulas, we can generate more realistic ship wave data vector diagrams, thereby presenting a more realistic ship wave effect in the simulation system. Although this method has a high demand for computing resources, it can provide real ship wave data and effects, which is very valuable for scientific research and opens up more possibilities for future ship simulation experiments. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention discloses a method for superimposing three-dimensional sea waves and ship-traveling waves, which specifically comprises the following steps:

[0005] A ship wave wake model was established in the Unity engine, and the wave height and normal data of the ship wave wake were generated according to the Kelvin ship wave formula;

[0006] Preprocessing the data of the ship wave wake model and generating a vector diagram, optimizing the wave height and normal data of the ship wave wake according to the Kelvin arm and the actual sailing wave phenomenon of the ship;

[0007] Based on the ship simulation system, the ship's wave wake is superimposed on the three-dimensional waves, and the ship's wave following effect is added according to the movement of the ship.

[0008] Furthermore, the ship wave wake model includes a ship wave Kelvin wake wave height model and a ship wave wake normal model.

[0009] Furthermore, when optimizing the wave height and normal data of the ship's wave wake: the rough signal is filtered based on the Kelvin arm, and the overlapping part is removed according to the actual driving effect to eliminate the influence of phase error and frequency offset.

[0010] Furthermore, according to the world coordinates of the ship in the ship simulation system, the ship wave data is superimposed with the three-dimensional ocean wave data to realize the actual effect of the ship wave on the sea surface.

[0011] Furthermore, a positioning skeleton plug-in is added to the ship, which is responsible for providing the position information of the ship. When the ship moves, the real-time position of the ship is obtained to achieve the ship wave following effect.

[0012] Due to the adoption of the above technical solution, the present invention provides a method for superimposing three-dimensional sea waves and ship waves. The method is based on Kelvin ship wave theory and can effectively extract the characteristics of ship waves. Combined with the Unity engine, the simulation of ship waves has high interactivity, flexibility and scalability, which can effectively solve the problems of difficult simulation and false simulation in traditional simulation of sea wave effects. It provides technical support for theoretical research on ship waves, analysis of ship wave resistance, ship design, construction of water projects, etc., and has very important research value and promotion significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 It is the base map of the ship's traveling waves in the present invention.

[0015] Figure 2 This is an effect diagram of three-dimensional ocean waves superimposed on ship waves in the present invention.

[0016] Figure 3 This is a diagram showing the wave following effect of a ship when turning in the present invention.

[0017] Figure 4 Generate graphs for ship wave Matlab verification.

[0018] Figure 5 This is a flow chart for superimposing three-dimensional ocean waves and ship-traveling wave scenes simulation. DETAILED DESCRIPTION

[0019] In order to make the technical solutions and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention:

[0020] like Figure 5 The method for superimposing three-dimensional sea waves and ship-traveling waves is shown, and specifically comprises the following steps:

[0021] S1: Establish a ship wave wake model in the Unity engine, and generate the wave height and normal data of the ship wave wake according to the Kelvin ship wave formula;

[0022] S2: Preprocess the data of the ship's wave wake model and generate a vector diagram, and optimize the data according to the Kelvin arm and the real display effect;

[0023] S3: Based on the ship simulation system, the ship's wave wake is superimposed on the three-dimensional waves; and according to the ship's movement, the ship's wave following effect is added when the ship is traveling.

[0024] Steps S1 / S2 / S3 are executed sequentially;

[0025] Furthermore, the Kelvin wake mathematical expression is used in the Unity engine to establish a ship wave wake model, where the Kelvin wake wave height expression is:

[0026]

[0027] in,

[0028]

[0029] μ is the ship speed, g=9.8 is the gravitational acceleration, D is the draft of the ship when sailing, b is half the width of the ship, and l is half the length of the ship. The wave height data of the corresponding instantaneous position point can be obtained from the above formula. At the same time, according to the different types of simulated ships, the ship wave simulation of different types of ships can be realized by changing the parameters;

[0030] The process of preprocessing the data of the ship wave wake model and generating a vector diagram and optimizing the data according to the Kelvin arm and the real display effect is as follows:

[0031] S21: data preprocessing;

[0032] according to Figure 4 Matlab verifies the generated graph and counts the characteristic wave height of the ship wave, that is, retains the data that can represent the shape of the ship wave, such as Figures 1 to 4 As shown, the noise data with the absolute value of wave height less than 0.15 is removed.

[0033] S22: Optimized according to Kelvin arm and display effect;

[0034] Combining the Kelvin arm angle and the actual display effect, the appropriate angle is selected, the useless data outside the appropriate angle is removed, and a linear fading effect is added to the wake of the ship's waves at the rear, which increases the authenticity of the ship's waves when the ship is moving.

[0035] Figure 2 This is an effect diagram of three-dimensional sea waves superimposed on ship waves in the present invention;

[0036] Furthermore, the superposition of ship waves on three-dimensional waves, where the three-dimensional waves include OchiHubble wave spectrum, Ittc wave spectrum, and Jonswap wave spectrum, may require appropriate adjustment of wave spectrum parameters or addition of wave spectrum types according to different simulation research needs of users.

[0037] Furthermore, the OchiHubble wave spectrum is a spectrum that divides the entire spectrum into a low-frequency part and a high-frequency part. The whole is composed of these two parts, and each part has three independent parameters. The wave spectrum expression is:

[0038]

[0039] Where Hs is the effective wave height, ω is the spectrum peak frequency, λ is the shape parameter, and j=1 and 2 represent the low-frequency part and the high-frequency part respectively.

[0040] Furthermore, the Ittc wave spectrum is modified based on the PM spectrum, and the obtained wave spectrum expression is:

[0041]

[0042] in is the average wave height of Trinity and ω is the spectrum peak frequency.

[0043] Furthermore, the Jonswap wave spectrum has two expressions, the spectrum expression represented by wind speed and wind range:

[0044]

[0045] Where α is a dimensionless constant, which can be taken as α = 0.0076 (gx / U 2 ) -0.22 ; x is the wind distance, U is the average wind speed; ω p is the spectrum peak frequency, we can take ω p =22(g / U)(gx / U 2 ) -0.33 ;γ is the peak enhancement factor, with an average value of 3.3;σ is the peak shape parameter, when ω≤ω p When ω>ω, σ=0.07; p When , take σ=0.09;

[0046] Spectral expression expressed by wave height and wave period:

[0047]

[0048] Where T p is the spectrum peak period.

[0049] Furthermore, in order to achieve the wave following effect when the ship is moving, a positioning skeleton plug-in is added to the ship, which is responsible for providing the position of the ship. When the ship moves, by obtaining the real-time position of the ship, the wave following effect can be achieved, which enhances the visual effect and realism.

[0050] Based on Kelvin ship wave theory, the characteristics of ship waves can be accurately shown, which is the scientific basis for the simulation of ship waves. At the same time, combined with the powerful Unity engine for simulation, the simulation has a high degree of interactivity, flexibility and scalability, and can present corresponding simulation effects according to different needs.

[0051] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for superimposing three-dimensional sea waves and ship-traveling waves, characterized in that include: A ship wave wake model was established in the Unity engine, and the wave height and normal data of the ship wave wake were generated according to the Kelvin ship wave formula; Preprocessing the data of the ship wave wake model and generating a vector diagram, optimizing the wave height and normal data of the ship wave wake according to the Kelvin arm and the actual sailing wave phenomenon of the ship; Based on the ship simulation system, the ship's wave wake is superimposed on the three-dimensional waves, and the ship's wave following effect is added according to the movement of the ship.

2. A method for superimposing three-dimensional sea waves and ship-traveling waves according to claim 1, characterized in that: The ship wave wake model includes a ship wave Kelvin wake wave height model and a ship wave wake normal model.

3. The method for superimposing three-dimensional sea waves and ship-traveling waves according to claim 1, characterized in that: When optimizing the wave height and normal data of the ship's wave wake: the rough signal is filtered based on the Kelvin arm, and the overlapping parts are removed according to the actual driving effect to eliminate the influence of phase error and frequency offset.

4. The method for superimposing three-dimensional sea waves and ship-traveling waves according to claim 1, characterized in that: According to the ship world coordinates in the ship simulation system, the ship wave data and the three-dimensional ocean wave data are superimposed to realize the actual effect of the ship wave on the sea surface.

5. The method for superimposing three-dimensional sea waves and ship-traveling waves according to claim 4, characterized in that: A positioning skeleton plug-in is added to the ship. This plug-in is responsible for providing the ship's position information. When the ship moves, the real-time position of the ship is obtained to achieve the ship's wave following effect.

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