A Comparison between Computer- and Process-Oriented Design Methods for a Ship's Heading Control

Abstract

This papers presents a comparison between two different approaches for the synthesis of a controller in a Sampled-Data system. The first one is based on the traditional computer oriented synthesis, in which an analogue controller is designed and then discretized for its implementation. The second one is based on a process oriented approach, in which a considering a continuous-time representation of the discrete controller is used. For the computer oriented synthesis, a PID controller is designed in continuous time and then converted to a discrete model using a Tustin transformation. The process oriented method is based on the Parametric Transfer Function approach, and it consists on a quadratic optimization of a control loop. The DirectSD Matlab toolbox is used to solve the numerical optimization problem in this case. By means of numerical simulations on a Ship's model, we compare advantages and disadvantages of each approach.