Ship Steering Control Problem Performance Criterion for Energy Minimisation

The indefinite cost-function often used for ship steering autopilot design is transformed into a new dynamic cost function form which can be minimised by a standard LQG control strategy. An optimal solution to the problem is shown to exist. The optimal controller can be calculated in the frequency domain by solving the resulting single-input single-output control problem using diophantine equations. Equivalently, the time-domain solution can be obtained by solving a Ricatti equation to give a state-feedback (or state estimate feedback) control solution. The approach is demonstrated using the model of a Very Large Crude Carrier (VLCC) and time-domain simulation results are presented.