| It is benefit to reduce risk, save cost and shorten the training time to train fishery crew by fishing simulator. The training can improve the trainees’comprehensive ability and practical analysis ability. In order to develop dynamic simulation of fishing operation process for pair trawling and purse seine, hydrodynamic mathematical model of pair trawling and purse seine gear system with high confidence are established based on lumped mass method respectively. By using highly precise integration algorithm to solve large nonlinear differential equations and GPU(Graphic Process Unit) parallel acceleration technology based on CUDA(Compute Unified Device Architecture) ensure the real-time in solution of models. Considering the coupling between fishing boats and fishing gear system, the fishing simulation system of pair trawling and purse seine are built up, which has laid the solid foundation to the development of fishing simulator.Hydrodynamic numerical model with high confidence is the foundation of the dynamic simulation in pair trawling and purse seine. A method is proposed to build the mathematical model of pair trawling and purse seine system based on lumped mass method. In the modeling process, the fishing gear system is divided into warp (or purse line) and fishing net. Hydrodynamic models are established separately, which are connected by boundary conditions reflecting the influence of each other. In this method, fishing gear are modeled as a group of lumped mass points interconnected with springs without mass. It is assumed that the mass points of knots are spherical and bars are cylindrical. The hydrodynamic model of the mass points is established according to Newton’s second law; Based on that, considering the coupling between fishing boats and fishing gear system, the dynamic simulation of pair trawling and purse seine can be realized. The simulation results and the model test results are compared and analyzed to verify the validity of the model.Fishing gear system consists of a large number of flexible elastic components. By applying the lumped mass method to discrete it, a large number of nonlinear differential equations are formed, while its stable solving time steps are limited by the flexible body rigidity. It is necessary for efficient numerical solution to ensure the stability and improve the efficiency of the hydrodynamic model solving. A numerical solution of the hydrodynamic model for fishing gear system is proposed based on precise integration method, then nonlinear equations are solved with the exponential matrix 2N algorithms and integral subsection integration in function matrix. Compared with the traditional numerical solution method for fishing gear system, this method has higher precision and computational efficiency. Besides, it is universally applicable for equations which modeled based on lumped mass method.The number of nodes in trawling and seine net system are usually up to a million levels. Even if the fishing net is simplified by using mesh merging technique, it is hard to ensure real-time of model solution. GPU parallel technology based on CUDA is adopted to solve fishing gear hydrodynamic model. By opening up array in global memory, position of all the mass points in previous frame are stored, lookup connected nodes position by thread index to calculate tension, all equations of bars and knots are solved in parallel. The experimental results show that the parallel solution with GPU can ensure the computational accuracy and effectively improve the computing efficiency, which can ensure the real-time of trawling and seine system dynamic simulation.Finally,3D visualization of pair trawling and purse seine operation process are realized by the scene management software OSG (OpenSceneGraph).With the combination of the maritime simulator, it has initially realized the pair trawling and purse seine operation modules in fishing simulator. This study has practical significance to improve the simulation effects of underwater flexible body and promote the research and development of fishing simulator.That would provide the theoretical basis and technical support for the further research of fishing simulator. |
