System Simulation Of Course-keeping For Ships Based On VB DLL

The research of course-keeping for ships is one of the prevalent problems in ship motion control areas, many researchers have simulated successfully by Matlab and obtained many results with academic values for reference. Because a Matlab program can't be applied into actual engineering directly, the simulation is carried out by VB6.0 in this paper. The designed controller performs task in heavy sea state and disturbance. The characterization of the disturbances acting on the ship is essential to designing a course-keeping controller with good performance. In order to protect the controller, the algorithm is written by DLL in this paper.This paper uses the nonlinear Norrbin six-degree of freedom motion equations for ships. The course-keeping autopilot is designed by studying of closed-loop gain shaping algorithm, and the controller algorithm is discrete by difference and bilinear transformation methods. This algorithm is written by ActiveX DLL, and the program is compiled into a .dll file which can be accessed by the main program.In the case of Beaufort No.8 wind scale and wind direction 90°, the controller can keep the setting course well. Simulation results are satisfactory so that the controller has strong robust stability. The controller is designed by nominal model, while simulated by nonlinear model, therefore it has good robustness.This paper presents ship's course-keeping system on VB simulation with animation of opening program based on Flash8.0, login, adding users, setting parameters, showing simulation results and so on. In the case of heavy sea state, the good results are still obtained, so the conclusion is that the designed controller has strong robustness. By using the .dll document the security of core program codes are saving very well.