A new and effective fuzzy PID autopilot for ships

Ship autopilots are usually designed based on the PD and PID controllers because of simplicity, reliability and easy to construct. However their performance in various environmental conditions is not as good as desired. This advantage can be overcome by adjusting works or constructing adaptive controllers. But those methods are complex and not easy. This paper presents a new method for constructing ship autopilots based on combination of fuzzy logic control and linear control. The new ship autopilot has the advantages of both the PID and FLC control methodologies: easy to construct, optimal control laws can be established based on ship masters knowledge. Therefore, the new ship autopilot can be well adapted with parameter variations and strong environment effects. Simulation using MATLAB software for a ship with real parameters in course keeping and course changing maneuvers shows high effectiveness of the new autopilot in comparison with ordinary PID ship autopilots.