A ship oscillation and visual wave motion matching method, a terminal device and a medium

Abstract

The present application relates to a kind of ship oscillation and visual wave motion matching method, terminal equipment and medium, the method includes: the corresponding rectangular boundary frame of ship body projection to sea surface is calculated;Rectangular boundary frame is gridded, wherein grid line is parallel with the edge of rectangular boundary frame;The height value corresponding to each grid point is calculated;The average height value is obtained by calculating the average of the height value of all grid points, and the expansion degree of water is obtained by multiplying the average height value by grid area;Based on the expansion degree of water and the input ship motion related parameters, the ship motion in three degrees of freedom of roll, pitch and heave under the influence of wave is calculated;Based on the principle of MMG modeling, the ship motion in three degrees of freedom of surge, sway and yaw is calculated;The motion of ship body in six degrees of freedom is superimposed, and the simulation motion of ship body is obtained.The present application makes the motion view of ship in sea wave environment in navigation simulator more realistic, and achieves the effect of sea navigation practice.

Description

Technical Field

[0001] This invention relates to the field of maritime teaching and training technology, and in particular to a method, terminal equipment and storage medium for matching ship sway with visual wave motion. Background Technology

[0002] Nautical simulators can simulate the motion of ships in various sea conditions in real time on land, giving ship operators an immersive experience and enabling them to practice actual navigation operations in a virtual environment, achieving the same training effect as real-ship training. Modern maritime education is inseparable from navigation simulators. The marine environment interferes with the six degrees of freedom of a ship's motion (sway, pitch, heave, roll, pitch, and bow), affecting normal ship operations and, in severe cases, even causing capsizing. However, in traditional simulators, the matching method between ship motion simulation and visual wave motion still needs further research. They can only set simple parameters for the wave model, without real-time dynamic changes, which is insufficient to meet the needs of realistic simulation. Furthermore, they cannot select ship types to match waves, thus failing to reflect the effects of ship motion changes in a wave environment within the simulation simulator. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a method for matching ship swaying with visual wave motion, a terminal device, and a storage medium to enhance the usability of the navigation simulator and realistically reflect the ship's navigation status in a wave environment.

[0004] The specific plan is as follows:

[0005] A method for matching ship sway with visual wave motion includes the following steps:

[0006] S1: Project the ship's hull vertically onto the coordinate plane containing the sea surface, and calculate the rectangular bounding box corresponding to the hull projection;

[0007] S2: Mesh the rectangular bounding box, where the grid lines are parallel to the edges of the rectangular bounding box;

[0008] S3: Calculate the height value corresponding to each grid point;

[0009] S4: Calculate the average height value of all grid points to obtain the average height value, and multiply the average height value by the grid area to obtain the water expansion rate;

[0010] S5: Based on the water's swelling degree and the input ship motion-related parameters, calculate the ship's motion in three degrees of freedom—roll, pitch, and heave—under the influence of waves.

[0011] S6: Based on the MMG modeling principle, calculate the ship's motion in the three degrees of freedom of pitch, sway and roll;

[0012] S7: Superimpose the motions of the hull in six degrees of freedom to obtain the simulated motion of the hull.

[0013] Furthermore, the gap between adjacent grid lines is set to 1 meter.

[0014] Furthermore, the height value is calculated using a wave model, and the calculation formula is as follows:

[0015]

[0016] Where h(x,z,t) represents the height of the point with x-axis coordinates and z-axis coordinates at time t, where the x-axis and z-axis represent the two coordinate axes contained in the coordinate system plane corresponding to the sea surface, and ζ k Let λ represent the amplitude of the k-th wave. k ω represents the wavelength of the k-th wave. k Let θ represent the velocity of the k-th wave. k The x-axis represents the angle between the X-axis and the incident direction of the k-th wave in the world coordinate system, x represents the coordinate of the X-axis, z represents the coordinate of the Z-axis, t represents the time, k represents the wave number, and K represents the total number of waves.

[0017] Furthermore, ship motion-related parameters include wave parameters and ship parameters.

[0018] A terminal device for matching ship sway with visual wave motion includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the method described above in the embodiments of the present invention.

[0019] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method described above in the embodiments of the present invention.

[0020] This invention employs the above technical solution to make the visual experience of ship movement in a wave-filled marine environment in a navigation simulator more realistic, achieving the effect of practical maritime navigation training. This invention changes the training model for maritime students and solves the difficulty faced by most maritime colleges in lacking training vessels for students' practical maritime navigation training. Attached Figure Description

[0021] Figure 1 The diagram shown is a flowchart of Embodiment 1 of the present invention.

[0022] Figure 2 The diagram shown is a schematic of the coordinate system in this embodiment.

[0023] Figure 3 The diagram shown is a schematic diagram of the hull projection mesh in this embodiment. Detailed Implementation

[0024] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments, and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention.

[0025] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0026] Example 1:

[0027] This invention provides a method for matching ship rolling with visual wave motion. To make the visual image of a ship moving in waves more realistic, the method in this embodiment is based on the following three assumptions:

[0028] (1) Treat the ship as a steel body and do not consider elastic deformation.

[0029] (2) Ocean waves are deep-water micro-waves composed of a finite number of sinusoidal waves with different amplitudes, periods and propagation directions.

[0030] (3) The six degrees of freedom can be calculated individually and then superimposed.

[0031] Based on the above assumptions, such as Figure 1 As shown, the method in this embodiment includes the following steps:

[0032] S1: Project the ship's hull vertically onto the coordinate plane containing the sea surface, and calculate the rectangular bounding box corresponding to the hull projection.

[0033] S2: Mesh the rectangular bounding box, where the grid lines are parallel to the edges of the rectangular bounding box.

[0034] S3: Calculate the height value corresponding to each grid point.

[0035] S4: Calculate the average height value of all grid points to obtain the average height value, and multiply the average height value by the area of ​​a single grid to obtain the water expansion rate.

[0036] S5: Based on the water's swelling degree and the input ship motion-related parameters, calculate the ship's motion in the three degrees of freedom of roll, pitch, and heave under the influence of waves.

[0037] S6: Based on the MMG modeling principle, calculate the ship's motion in the three degrees of freedom of pitch, roll, and yaw.

[0038] S7: Superimpose the motions of the hull in six degrees of freedom to obtain the simulated motion of the hull.

[0039] This embodiment defines two coordinate systems, such as Figure 2 As shown. The first is the world coordinate system, whose origin O is fixed at a certain position on the sea surface. The sea surface is composed of the X-axis and Z-axis, and the Y-axis is perpendicular to the sea surface. The second is the ship's local coordinate system, which is attached to the ship and moves with the ship. Its origin G is located at the geometric center of the ship, and the X-axis is perpendicular to the Z-axis. S The axis points in the direction the ship is moving, Z. S The axis points to the starboard side (right-hand side) of the ship, Y S The axis is vertically upward.

[0040] The six degrees of freedom of a ship's motion include roll, pitch, heave, sway, sway, and yaw. Among these, roll, pitch, and heave are the degrees of freedom around the X-axis. S Y S and Z S The rotation of the axis is caused by vibrations induced by ocean waves. To achieve coordination between the ship's motion and the wave surface motion in the visual representation, this embodiment employs a hull meshing method. Steps S1-S2 generate a mesh as shown below. Figure 3 Therefore, the hull is projected onto the sea surface (X–Z plane) using a grid. In this embodiment, the gap between adjacent grid lines is set to 1 meter. To improve simulation speed, reduce computational load, and maintain simulation accuracy, the grid division should be determined based on the performance of the configured computer and simulation test results. Typically, the grid is dynamically divided according to the ship length, rather than using a fixed-length grid. This division method is applicable to simulations of ships of different lengths.

[0041] When evaluating the height value at a grid point (the intersection of two grid lines), this embodiment assumes no ships are displayed and calculates the height value using a wave model. The calculation formula for the wave model is as follows:

[0042]

[0043] Where h(x,z,t) represents the height of the point with x-axis coordinates and z-axis coordinates at time t, where the x-axis and z-axis represent the two coordinate axes contained in the coordinate system plane corresponding to the sea surface, and ζ k Let λ represent the amplitude of the k-th wave. k ω represents the wavelength of the k-th wave. k Let θ represent the velocity of the k-th wave. k The x-axis represents the angle between the X-axis and the incident direction of the k-th wave in the world coordinate system, x represents the coordinate of the X-axis, z represents the coordinate of the Z-axis, t represents the time, k represents the wave number, and K represents the total number of waves.

[0044] Once the height of each grid point in the grid is calculated, the water dilatation is determined by multiplying the average height by the grid area (the area of ​​the rectangular bounding box). Based on the water dilatation, existing algorithms can be used to calculate the forces that cause the ship's motion, thereby obtaining the ship's motion in the three degrees of freedom of roll, pitch, and heave.

[0045] When calculating the wave forces and moments acting on the hull, it is assumed that the waves are continuous and the disruption of wave continuity by the hull is not considered. After calculating the average height value corresponding to the grid, the local forces and moments acting on the hull are calculated by comparing it with the waterline at the local grid of the hull under still water conditions. Finally, the calculation results of all grids are superimposed to obtain the wave forces and moments acting on the entire hull. These wave forces and moments are then used to calculate the ship's motion in the three degrees of freedom of roll, pitch, and heave using Newton's second law. Since the wave parameters are obtained in real time and used in subsequent ship motion calculations, the ship's motion can be perfectly matched with the waves.

[0046] The calculation of the ship's other three degrees of freedom motion (swell, roll, and pitch) is carried out using the relatively mature MMG modeling principle in existing technology.

[0047] Since, under normal circumstances, the six-free motion of a ship can be considered as the superposition of the three-degree-of-freedom motion under the influence of waves and the three-degree-of-freedom motion under the action of the hull, rudder, propeller, etc., from the perspective of simulators, this approach is feasible.

[0048] In practical applications, 3D visualization software can superimpose the motions of a ship under its six degrees of freedom to obtain a simulated motion of the ship.

[0049] The mathematical model for the six-degree-of-freedom planar motion of a ship is as follows:

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056] Where m, m x m yThese represent mass, additional mass on the x-axis, and additional mass on the y-axis, respectively; the "." symbol indicates acceleration; u represents forward velocity; q represents pitch velocity; w represents heave velocity; v represents sway velocity; r represents yaw velocity; p represents roll velocity; I x I y I z J represents the moments of inertia of the ship's hull about the x-axis, y-axis, and z-axis, respectively; x J y J z These represent the additional moments of inertia of the hull about the x-axis, y-axis, and z-axis, respectively; subscripts H, P, R, and W represent the hull, propeller, rudder, and waves, respectively; F H T H F represents the viscous force and torque of a fluid; P T P Indicates propeller thrust and torque; F R T R Indicates rudder force and torque; F W T W Indicates wave force and moment; X H Y H Z H Represents force F H Components on the X, Y, and Z axes; X P Y P Z P Represents force F P Components on the X, Y, and Z axes; X R Y R Z R Represents force F R Components on the X, Y, and Z axes; Z W Represents force F R Components on the X, Y, and Z axes; K H M H N H Indicates torque T H Components on the X, Y, and Z axes; K P M P N P Indicates torque T P Components on the X, Y, and Z axes; K R M R N R Indicates torque T R Components on the X, Y, and Z axes; K W M W Z W Indicates torque T W Components on the X, Y, and Z axes.

[0057] The first three equations above describe the three-degree-of-freedom planar motion of the ship, but do not take into account the increase in ship resistance caused by waves, as well as planar drift and bow turning motion; the last three equations describe the ship's roll, pitch, and heave motions caused by waves.

[0058] The calculation methods for wave forces and moments corresponding to ship roll, pitch, and heave are as follows:

[0059]

[0060]

[0061]

[0062] Where i and j represent the i-th and j-th small squares in two directions corresponding to the meshed hull, respectively (i, j are the indices of each small square); d j Let represent the draft of the j-th small square corresponding to the hull; ρ represent the density of seawater; Δs represent the area of ​​the small square; x j Represents the x-axis coordinate; y j This represents the y-axis coordinate.

[0063] Ship motion-related parameters are the parameters used in ship motion calculations, including wave parameters and ship parameters. Wave parameters include wave frequency, amplitude, wave direction, ocean currents, and wind, while ship parameters include ship resistance and thrust, and hull form parameters.

[0064] This invention can handle different ship types and sea conditions without sacrificing efficiency, helping users understand the motion of ships encountering waves, currents, and wind. Users can adjust wave and ship parameters through the software interface to automatically generate ship motion simulations under different environments and ship types, resulting in numerous ship-environment interactions that make learning more engaging. To achieve coordination between ship motion and wave surface motion in the visual representation, this embodiment employs a hull meshing method. Based on Newton's laws and other fundamental physical motion models, this embodiment calculates the ship's motion amplitude in real time, resulting in high fidelity simulation results.

[0065] Example 2:

[0066] The present invention also provides a terminal device for matching ship sway with visual wave motion, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the method embodiment described above in Embodiment 1 of the present invention.

[0067] Furthermore, as an executable solution, the ship sway and visual wave motion matching terminal device can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The ship sway and visual wave motion matching terminal device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the above-described composition of the ship sway and visual wave motion matching terminal device is merely an example and does not constitute a limitation on the ship sway and visual wave motion matching terminal device. It may include more or fewer components than described above, or combine certain components, or different components. For example, the ship sway and visual wave motion matching terminal device may also include input / output devices, network access devices, buses, etc., and this embodiment of the invention does not limit this.

[0068] Furthermore, as an executable solution, the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. This processor is the control center of the ship's sway and visual wave motion matching terminal equipment, connecting all parts of the equipment via various interfaces and lines.

[0069] The memory can be used to store the computer programs and / or modules. The processor, by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory, realizes various functions of the ship sway and visual wave motion matching terminal device. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a function; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0070] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the methods described in the embodiments of the present invention.

[0071] If the module / unit integrated with the ship sway and visual wave motion matching terminal device is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), and a software distribution medium, etc.

[0072] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art will understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A method for matching ship sway with visual wave motion, characterized in that, Includes the following steps: S1: Project the ship's hull vertically onto the coordinate plane containing the sea surface, and calculate the rectangular bounding box corresponding to the hull projection; S2: Mesh the rectangular bounding box, where the grid lines are parallel to the edges of the rectangular bounding box; S3: Calculate the height value corresponding to each grid point; the height value is obtained through wave model calculation, and the calculation formula is: in, This represents the height value of the point with x-axis coordinates and z-axis coordinates corresponding to time t. The x-axis and z-axis represent two coordinate axes contained in the coordinate system plane corresponding to the sea surface. This represents the amplitude of the k-th wave. This represents the wavelength of the k-th wave. Represents the velocity of the k-th wave. The angle between the X-axis and the incident direction of the k-th wave in the world coordinate system is represented by t, where t represents time, k represents the wave number, and K represents the total number of waves. S4: Calculate the average height value of all grid points to obtain the average height value, and multiply the average height value by the grid area to obtain the water expansion rate; S5: Calculate the wave force and moment on the hull based on the water's swelling degree. Based on the wave force, moment, and input ship motion parameters, calculate the ship motion in the three degrees of freedom of roll, pitch, and heave under the influence of waves. S6: Based on the MMG modeling principle, calculate the ship's motion in the three degrees of freedom of pitch, sway and roll; S7: Superimpose the motions of the hull in six degrees of freedom to obtain the simulated motion of the hull.

2. The method for matching ship sway with visual wave motion according to claim 1, characterized in that: The gap between adjacent grid lines is set to 1 meter.

3. The method for matching ship sway with visual wave motion according to claim 1, characterized in that: Ship motion-related parameters include wave parameters and ship parameters.

4. A terminal device for matching ship swaying with visual wave motion, characterized in that: It includes a processor, a memory, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of the method as described in any one of claims 1 to 3.

5. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 3.

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