QFT Autopilot Design For Robust Control Of Ship Course-Keeping And Course-Changing Problems

Abstract

This paper describes the design steps of robust QFT autopilot for the course-keeping
and course-changing control of a ship, in the presence of disturbances. The ship model has
parametric uncertainties, caused by the variations of hydrodynamic coefficients with the speed of
the ship. Knowing the variation ranges of the model parameters, the QFT method (Quantitative
Feedback Theory) can be used to design the ship autopilot with certain performance
specifications. The autopilot must satisfy the robust stability, tracking performance and
disturbance rejection conditions, for all ship models generated by the parameter variations within
the uncertainty ranges.