Cascade pseudo derivative feedback control algorithm and its application to design of autopilots

Autopilots based on proportional, integral plus derivative (PID) controllers have been used to steer ship for many years. The main drawback of conventional PID autopilots is their lack of adaptivity, and for this reason various adjustments to the controller gain settings are needed if they are to achieve good performance throughout the operating range of the ship. The design of autopilots for ship steering control based on the cascade pseudo derivative feedback (PDF) control algorithm is discussed. The simulation results show the superiority of the autopilot based on cascade PDF algorithm. The cascade PDF autopilot has an improved transient behavior and is robust to variation in the parameters and nonlinearities of the ship dynamics