Educational autopilot - a practical approach

The approach used for a computer-based system for collecting navigational data and developing an autopilot for the training ship used by the maritime schools of the Aland Islands in Finland is presented. Using the collected data, models for how the rudder angle responds to rudder command and how the ship responds to rudder angle are identified. Based on simulations of the identified models, an inner, nonlinear, controller for the rudder angle and an outer PID controller for the course are designed and evaluated in practice. The main contributions of the present study are the educational purpose and the practical approach: E.g., since the system is intended for educational use, a central aim is the keep all parts of the system translucent and comparable with existing navigational systems. Also, due to the limitations of the equipment of the training ship some practical challenges are tackled, e.g., the characteristics of the rudder steering necessitating nonlinear control.