Design of dynamic positioning systems using hybrid CMAC-based PID controller for a ship

The ship motion is a type of complicated nonlinear motion. It is very difficult to measure the precise hydrodynamic parameters when the ship is at sea. Moreover, the external disturbance forces coming from wind, waves and water current are changing at any moment. So, it is necessary to study new control techniques, with robust and adaptive properties, to implement precise position for dynamic positioning vessels. PID control law is a good robust and adaptive control law for a type of definite systems that precise modeling can be gotten in mathematics. But PID control results are not satisfactory for complex nonlinear systems such as ship motion. The neural network has self-learning and adapting ability, so we can combine the PID with neural network to build the strong robust and adaptive controller. In this paper, CMAC-based PID controller is studied. The simulation results show that the new control method is effective with strong robust and adaptive capability, and it can be applied to marine dynamic positioning systems.