Uniform Design of Heading and Track Controllers for Ship Autopilot

Uniform approach to selection of PID settings for heading and path tracking controllers that create a cascade control system for ship autopilot is presented. Uniformity of the design follows from observation that for each of the controllers the controlled plant looks like an integrator with time constant. In case of the heading controller, the plant is represented by the known Nomoto model. Due to elimination of the plant time constant by the controller, each of the closed loop systems becomes of 2nd order. One assumes that such system should have a double time constant, different in a prescribed ratio from time constant of the controlled plant. It is shown that the heading controller designed in this way suppresses disturbances better than the controller with standard settings.