Modeling And Controlling Of Ship Motion Simulator

The ship motion simulator can simulate the complex motion of the ship,which is produced by the six degrees of freedom,such as swing,sway,heave,roll,pitch and yaw.At present,it has been widely used in the simulation of ship equipment and the training of seafarers,the degree of its development directly affects the construction of national defense and the development of national economy.In China,the research on ship motion simulator is relatively late and the foundation is poor.In order to further improve the quality and performance of the simulator,it is necessary to study the theory and control technology.In this paper,the kinematics,dynamics,workspace and control algorithm of the simulator are analyzed theoretically and verified by simulation,this provides a theoretical basis for the initial design of the simulator.Firstly,the kinematics and dynamics of the ship motion simulator are analyzed,and the mathematical model and the dynamic differential equation are established.The physical model of the simulator is built by the SimMechanics toolbox in MATLAB,and the kinematics and dynamics simulation is carried out under the given motion law,the simulation results can verify the correctness of each other with the kinematic and dynamic mathematical model of the theoretical analysis.For the relatively complex kinematics positive solution problem,Numerical iteration algorithm in the Newton method,inverse Broyden rank 1 method,Broyden-Fletcher-Shanno(BFS)rank 2 method and Broyden-Fletcher-Goldfarb-Shanno(BFGS)method is used to solve.The results show that the algorithm is convergent in the workspace.In addition,a new algorithm which can solve all the numerical solutions of the forward kinematics is introduced,which is called Newton field line method.Secondly,on the basis of the forward and inverse solution of the kinematics model,a one-dimensional search method is used to search the boundary curve of the workspace of the simulator and calculate the total volume of the workspace.The influence of different parameters on the workspace size is analyzed by the control variable method so as to optimize the structure parameters of the simulator,this is the key problem in the initial design of the simulator.Thirdly,the PID controller and ADRC(auto disturbance rejection)controller are added to the 3D physical model of the simulator and the simulation is compared under the same given motion law.The results show that the accuracy,dynamic performance and tracking performance of the ADRC controller are better than that of the PID controller.Finally,based on the previous theoretical analysis,the real-time simulation platform of ship motion simulator is designed.The upper computer adopts OPC communication technology to realize the real-time communication between MATLAB and Fameview.In the Simulink simulation part,the RT timer module is added to ensure the synchronization of simulation time and real time.MATLAB can be used to calculate the real time calculation of the displacement of the telescopic pole through the OPC to Fameview.If the simulation platform is put into use by the lower computer,Fameview can be used in the serial communication mode to transfer the real-time calculation of the displacement of the telescopic pole to the lower computer(such as PLC),the real time control of the motor can be realized by PLC and servo drive unit.