Designing of Reference Signals that Considered Heading's Initial Conditions and Steering Gear's Limitations

This paper proposes designing of reference signals that realize a trajectory planning for course-changing in heading control system for a ship. The trajectory planning sets not only a designated quantity of turning but also the rate of turning with taking the ship characteristics and the steering gear limitation characteristics into account. To realize the trajectory planning, the reference signals are designed by analytical approach, which consist of the reference heading and the feedforward rudder inverting the ship model. The designing specifications consist of the course-changing conditions, the ship characteristics and the steering gear limitation characteristics. The maximum rudder angle and the maximum rudder rate in the feedforward rudder are derived by using relations between the reference heading and the ship model, and correspond to the limitation angle and the limitation rate in the steering gear, respectively. The equations of the reference heading are defined by time function with its initial conditions. First making the initial conditions set into zero, the reference signals are calculated. Secondly using the results, the reference signals which included the initial conditions are calculated. The designing of reference signals were verified by numerical calculations. We can conclude that our proposal method realizes the trajectory planning.