Autopilot is the equipment used in assisting ship steering, which helps to plan shipping trajectory and adjust shipping course. Therefore, shipping efficiency is improved, shipping security is reinforced and shipping cost is decreased. As a result, many countries have taken much investment in autopilot research and design. Based on the project - “development of intelligent autopilot system”, relevant researches are conducted on several aspects, including: Firstly, concept of "virtual course" is proposed. Compared with most autopilots using inner-outer control construction to follow desired course and trajectory respectively, "virtual course" based autopilot merely follows the virtual course, and ship control system is significantly simplified. Secondly, an approach to calculate the "virtual course" with trajectory cross-error and desired course is proposed, and a fuzzy autopilot based on the "trajectory cross–error virtual course" is designed. Its trajectory tracking performance is compared with different parameters. Thirdly, Genetic Algorithm (GA) is used to adjust parameters of the fuzzy logic controller. Given a search space, GA helps to find out a set of optimal or sub-optimal parameters. Performance of the fuzzy autopilot is greatly improved in consequence. Fourthly, since "trajectory cross error virtual course" based fuzzy autopilot is very sensitive to variation of the parameters, fuzzy autopilot based on "hen-dog tracking virtual course" is designed. Simulation results illustrate that the autopilot is more adaptive to variation of ship speed, and easier for design and implementation. Finally, summary is given, and research prospect is analyzed.
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