Joint simulation method for ship navigation control strategy verification based on computational fluid mechanics

Abstract

The invention relates to a joint simulation method for ship navigation control strategy verification based on computational fluid mechanics. The joint simulation method comprises the following steps: step 1, establishing a ship model numerical simulation environment under STAR-CCM +; step 2, establishing a ship horizontal plane track course controller module based on SIMULINK; step 3, establishing a ship horizontal plane track control model based on AMEsim; and step 4, completing an intelligent ship joint motion simulation test based on the STAR-CCM + lower ship model numerical simulation environment established in the step 1 and the AMEsim-based ship horizontal plane track control model established in the step 3. According to the invention, the problems of inaccurate controlled object model and single simulation verification means are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of ship automatic control technology and relates to a co-simulation method for verifying ship navigation control strategies based on computational fluid dynamics. Background Technology

[0002] Verification of ship navigation control strategies is a crucial process from control algorithm design to actual ship application. Traditional trajectory control strategy verification typically involves using empirical formulas or CFD (Computational Fluid Dynamics) to calculate hydrodynamic coefficients and construct a ship motion model. This is followed by controller design and simulation to determine the controller structure and basic parameter values. Finally, parameters are debugged on a real ship to complete the ship navigation controller development. The problem with this process is that deterministic hydrodynamic parameter modeling often fails to reflect the actual motion of the ship in the water, resulting in lengthy parameter tuning times or heavy reliance on experienced researchers.

[0003] With the rapid development of high-performance computers and numerical methods, CFD numerical simulation has become an effective means of conducting high-fidelity analysis of ship motion performance, thus laying a solid foundation for directly verifying control strategies based on the CFD numerical simulation environment. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a co-simulation method for verifying ship navigation control strategies based on computational fluid dynamics, thereby overcoming the problem that ship navigation control strategy verification based on traditional hydrodynamic parameter modeling cannot accurately reflect the actual motion of the ship.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution: A co-simulation method for verifying ship navigation control strategies based on computational fluid dynamics includes the following steps: Step 1: Establish a numerical simulation environment for the ship model under STAR-CCM+; Step 2: Establish a ship horizontal plane track and heading controller module based on SIMULINK; Step 3: Establish a ship horizontal plane trajectory control model based on AMEsim; Step 4: Based on the numerical simulation environment of the ship model under STAR-CCM+ established in Step 1 and the ship horizontal plane trajectory control model based on AMEsim established in Step 3, complete the simulation test of intelligent ship joint motion.

[0006] Moreover, step 1 includes: First, establish the three-dimensional model of the ship for simulation and the computational domain in the ship simulation environment, and set the boundary conditions for simulation. Then, the physical environment of the ship in the computational domain is established, including the turbulence model settings; the turbulence model uses SST. Turbulence model, which combines Model and The model's characteristics allow for use in free-flow regions. The model, and used in the near-wall region Model; Finally, set the parameters to enable the ship to perform six degrees of freedom motion in the computational domain, including: solver type, VOF wave parameters, boundary type, boundary conditions, mesh generation parameter settings, and DFBI object motion parameter settings.

[0007] Furthermore, in step 2, the path tracking error in the track tracking process is simplified into heading control using the navigation line-of-sight method.

[0008] Furthermore, the ship horizontal plane trajectory control model established in step 3 includes a CFD real-time simulation module, a data interaction module, a control module, and a servo simulation module. The CFD real-time simulation module is used to calculate the hydrodynamic forces acting on the hull in the numerical simulation environment of the ship model in real time. The data interaction module is used to exchange calculation data between STAR-CCM+ and AMEsim in real time. The control module is used to calculate the commanded rudder angle under the current trajectory deviation. The servo simulation module is used to simulate the motion law of the servo under the commanded rudder angle.

[0009] Furthermore, in step 4, when TAR-CCM+ and Amesim perform co-simulation, the two programs interact and exchange data through a TCP / IP interface during the simulation. The Amesim TCP unit contains input and output ports for exchanging data with STAR-CCM+. STAR-CCM+ calculates the hydrodynamic forces acting on various surfaces of the hull and the resulting hull displacement and attitude changes under these hydrodynamic forces. Amesim solves for the deviation between the hull displacement and attitude changes and the control target, and calculates the commanded rudder angle at this time through a control algorithm.

[0010] The advantages and positive effects of this invention are as follows: This invention addresses the issue that traditional six-degree-of-freedom ship models based on hydrodynamic coefficients cannot accurately represent the complexity of the marine environment, thus failing to accurately calculate the hydrodynamic loads experienced by the ship during navigation, leading to significant uncertainties in navigation controller verification. It proposes a joint ship motion simulation method based on STAR-CCM+ and AMESim. Leveraging the advantages of STAR-CCM+'s high-fidelity calculation of ship hydrodynamic loads and AMESim's universal interface and high-fidelity simulation of hydraulic components, this method effectively solves the problems of inaccurate controlled object models and limited simulation verification methods. This effectively overcomes the problem that traditional ship navigation control strategy verification based on hydrodynamic parameter modeling cannot accurately reflect the actual motion of the ship. Attached Figure Description

[0011] Figure 1 This is a flowchart illustrating the co-simulation method for verifying ship navigation control strategies according to the present invention. Figure 2 This is a three-dimensional model drawing of a ship used in the present invention; Figure 3 This is the mesh generation diagram in the STAR-CCM+ simulation environment for implementing this invention; Figure 4 This is a mesh diagram of the hull, propeller, and rudder in the STAR-CCM+ simulation environment for implementing this invention; Figure 5 This is a schematic diagram illustrating the line-of-sight navigation method for straight-track segments as described in this invention. Figure 6 A schematic diagram of the joint simulation environment for ship horizontal plane trajectory control based on AMEsim for implementing the present invention; Figure 7 The simulation test diagram shows the joint motion of intelligent ship Z-shaped trajectory tracking based on STAR-CCM+ and AMESim, which is the basis for the implementation of this invention. Detailed Implementation

[0012] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.

[0013] Currently, CFD simulation software such as STAR-CCM+ and ANSYS FLUENT come with actuator control development modules, such as STAR-CCM+'s Field Function and ANSYS FLUENT's UDF (User Defined Function), which provide corresponding control program instruction development modules. However, these modules are currently suitable for developing simple control strategies and are not conducive to the development of complex programs.

[0014] The application, published on December 20, 2024, with publication number CN 119167828 A, entitled "A Co-simulation Method for Calculating Coupled Dynamics of Wave Energy Harvesting Devices," proposes a co-simulation method using STAR-CCM+ and AMESim software. STAR-CCM+ is used to accurately simulate the hydrodynamic interaction between waves and the power generation device, while AMESim is used to model and calculate the energy conversion and dynamic response of the power generation system. The two software programs exchange data in real time and operate synchronously. This application only relates to the data exchange between STAR-CCM+ and AMESim and does not cover the design of control strategies.

[0015] The joint simulation method for verifying the ship navigation control strategy based on computational fluid dynamics is as follows. Please refer to Figures 1-7 , and the specific implementation steps are as follows: Step 1: Establish a ship motion simulation environment in STAR-CCM+, including: 1. Three-dimensional modeling of the ship According to the ship's lines data, a three-dimensional model of the ship is established. According to engineering requirements, the influence of the propeller, superstructure and other appendages on the flow field is ignored, and only the three-dimensional models of the hull, rudder and propeller shafting are established, as Figure 2 shown.

[0016] 2. Based on the established three-dimensional model of the ship, mesh generation, establishment of the computational domain and setting of boundary conditions To reduce the computational cost and the number of meshes, the volume force method of the virtual disk model is used to simulate the thrust of the propeller on the hull. The overlapping grid is used to achieve the coupled solution of the rudder movement. A total of 5 sets of computational meshes are divided, one background mesh, one hull mesh, and two rudder meshes. The range of the computational domain of the background mesh is -2.0Lpp < x < 2.0Lpp, -2.0Lpp < y < 2.0Lpp, -2.0Lpp < z < 1.0Lpp. The range of the computational domain of the overlapping grid is -0.3Lpp < x < 1.25Lpp, -0.3Lpp < y < 0.3Lpp, -0.3Lpp < z < 0.3Lpp. The range of the computational domain of the hull mesh is -0.2Lpp < x < 1.2Lpp, -0.2Lpp < y < 0.2Lpp, -0.2Lpp < z < 0.1Lpp. The range of the computational domain of the rudder mesh is -0.01Lpp < x < 0.033Lpp, -0.034Lpp < y < -0.02Lpp, -0.053Lpp < z < -0.015Lpp and -0.01Lpp < x < 0.033Lpp, 0.02Lpp < y < 0.034Lpp, -0.053Lpp < z < -0.015Lpp. Except that the outlet boundary is set as a pressure outlet, the boundary conditions of other computational domains are set as velocity inlets. During the mesh generation process: the meshes near the bow and stern of the ship are appropriately refined; the meshes near the free surface are appropriately refined. As Figures 3 to 4 shown is a schematic diagram of the topological structure of the mesh generation. The total number of meshes is 4.1 million, including 580,000 background meshes, 2.94 million overlapping meshes (the number of meshes in the overlapping computational domain minus the number of meshes in the hull computational domain), and 580,000 rudder meshes.

[0017] 3. Establish the physical environment of the ship in the computational domain, including the setting of the turbulence model.

[0018] This invention mainly simulates two media, water and air, and selects the model as the turbulence model for the simulation numerical simulation. This model combines Model and The model's characteristics allow it to be used in free-flowing regions. The model, while being used in the near-wall region Model.

[0019] 4. Set other parameters to enable the ship to perform six degrees of freedom motion in the computational domain, including: solver type, VOF wave parameters, boundary type and boundary conditions, mesh generation parameters, and DFBI object motion parameters.

[0020] This invention employs a solver type based on transient computation, with a simulation time step set to 0.05s, balancing simulation accuracy and computation time.

[0021] Step 2: Establish a ship horizontal plane track and heading controller module based on SIMULINK.

[0022] This invention simplifies path tracking error in the trajectory tracking process into heading control using the navigation line-of-sight method. The navigation line-of-sight method is already quite mature in application, and its principle is as follows: Figure 5 As shown, to drive the ship to converge to the discrete path point on the horizontal plane The path formed is the segment from the ship's center of mass to the path. lateral distance It needs to converge to 0, and the heading angle should be... convergence to Using the line-of-sight navigation method, the first step is to navigate from the ship's center of mass to... Vertical distance of the path segment as well as ( As captain, (where the number is a positive real number) can be used to calculate the line-of-sight guide point. Using coordinates in a fixed coordinate system, the distance from the ship's center of mass to the line-of-sight guidance point is then calculated. Line of sight navigation heading angle Then the heading angle convergence to This ensures that the hull position converges to a straight path segment. When the ship's center of mass is located at the path point radius is ( If the target point is within a circle containing positive real numbers, then the navigation target point will be switched to the next target point. .

[0023] Step 3: Establish a ship horizontal plane trajectory control model based on AMEsim.

[0024] The ship's horizontal trajectory control model includes a CFD real-time simulation module, a data interaction module, a control module, and a servo motor simulation module. The CFD real-time simulation module is used to calculate the hydrodynamic forces acting on the hull in the numerical simulation environment of the ship model in real time; the data interaction module is used for real-time exchange of calculation data between STAR-CCM+ and AMEsim; the control module is used to calculate the commanded rudder angle under the current trajectory deviation; and the servo motor simulation module is used to simulate the motion of the servo motor under the commanded rudder angle. This invention compiles the SIMULINK ship horizontal plane trajectory and heading controller module into a runnable control module in the AMESim software via the SL2AMECosim interface. After the subsequent simulation begins, the CFD inputs the ship's state information into the control model based on the hydrodynamic results. The control model then calculates the rudder angle command and inputs it into the servo motor simulation model. The CFD real-time simulation module calculates the hydrodynamic forces under the input rudder angle based on the input rudder angle information, and further calculates the changes in the ship's motion state under this force.

[0025] Step 4: Complete the joint motion simulation test of the intelligent ship based on STAR-CCM+ and AMESim Simcenter STAR-CCM+ can perform bidirectional co-simulation with Simcenter Amesim (used for dynamic system modeling). During co-simulation, the two programs interact and exchange data via a TCP / IP interface. The Amesim TCP unit contains input and output ports for data exchange with STAR-CCM+. STAR-CCM+ calculates the hydrodynamic forces acting on various surfaces of the hull and the resulting hull displacements and attitude changes. Amesim solves for the deviations between the hull displacements and attitude changes and the control target, and calculates the commanded rudder angle using a control algorithm. The AMESim platform can build accurate models of the controlled object and provides a dedicated interface for data interaction with Simulink software. This invention provides a co-simulation environment for ship horizontal plane trajectory control based on AMESim, as follows: Figure 6 As shown. In Figure 6 In the simulation, the output of the controlled object is the rudder angle (Commond Rudder), and the propeller force is simulated using a volumetric force model. Figure 6 In this context, u represents the ship's speed, v represents the ship's lateral speed, r represents the ship's bow turning angular velocity, psi represents the ship's current heading angle, and ksi and eta represent the ship's displacement in the x and y directions in the inertial coordinate system, respectively.

[0026] In this embodiment of the invention, the initial speed is set to 3 m / s, the initial position is [0,0], and the initial heading is 0°. In the Cartesian coordinate system, a straight line segment is set, with track points at [0,0], [500,500], [500,1000], and [1000,1500]. The propeller speed is 6.25 RPS, the maximum rudder angle is 35°, and six degrees of freedom motion is activated in STAR-CCM+. The co-simulation test results for track tracking are as follows: Figure 7 As shown.

[0027] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A co-simulation method for verifying ship navigation control strategies based on computational fluid dynamics, characterized in that: Includes the following steps: Step 1: Establish a numerical simulation environment for the ship model under STAR-CCM+; Step 2: Establish a ship horizontal plane track and heading controller module based on SIMULINK; Step 3: Establish a ship horizontal plane trajectory control model based on AMEsim; Step 4: Based on the numerical simulation environment of the ship model under STAR-CCM+ established in Step 1 and the ship horizontal plane trajectory control model based on AMEsim established in Step 3, complete the simulation test of intelligent ship joint motion.

2. The co-simulation method for verifying ship navigation control strategies based on computational fluid dynamics according to claim 1, characterized in that: Step 1 includes: First, establish the three-dimensional model of the ship for simulation and the computational domain in the ship simulation environment, and set the boundary conditions for simulation. Then, the physical environment of the ship in the computational domain is established, including the turbulence model settings; the turbulence model uses SST. Turbulence model, which combines Model and The model's characteristics allow for use in free-flow regions. The model, and used in the near-wall region Model; Finally, parameters are set to enable the ship to perform six degrees of freedom motion in the computational domain, including: solver type, VOF wave parameters, boundary type and boundary conditions, mesh generation parameter settings, and DFBI object motion parameter settings.

3. The co-simulation method for verifying ship navigation control strategies based on computational fluid dynamics according to claim 1, characterized in that: Step 2: Use the navigation line-of-sight method to simplify the path tracking error in the track tracking process into heading control.

4. The co-simulation method for verifying ship navigation control strategies based on computational fluid dynamics according to claim 1, characterized in that: The ship horizontal plane trajectory control model established in step 3 includes a CFD real-time simulation module, a data interaction module, a control module, and a servo motor simulation module. The CFD real-time simulation module is used to calculate the hydrodynamic forces acting on the hull in the numerical simulation environment of the ship model in real time. The data interaction module is used to exchange calculation data between STAR-CCM+ and AMEsim in real time. The control module is used to calculate the commanded rudder angle under the current trajectory deviation. The servo motor simulation module is used to simulate the motion law of the servo motor under the commanded rudder angle.

5. The co-simulation method for verifying ship navigation control strategies based on computational fluid dynamics according to claim 1, characterized in that: In step 4, during the co-simulation between TAR-CCM+ and Amesim, the two programs interact and exchange data through a TCP / IP interface during the simulation. The Amesim TCP unit contains input and output ports for exchanging data with STAR-CCM+. STAR-CCM+ calculates the hydrodynamic forces acting on various surfaces of the hull and the resulting hull displacement and attitude changes under these hydrodynamic forces. Amesim solves for the deviation between the hull displacement and attitude changes and the control target, and calculates the commanded rudder angle at this time through the control algorithm.

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