Identification and Minimization of Propulsion Losses Related to Ship Steering

摘要

This report presents the results of work on formulating and general characterizing of the merchant ship steering control problem during course-keeping operation in the open seas. The evaluation of performance of the uncontrolled and controlled ship in a seaway is conducted in terms of both yaw deviations and propulsion losses. A new steering design criterion based on minimizing the added resistance caused by rudder activity and hull drag of inertial origins caused by periodic yawing of a ship is developed and compared with other widely used approximate criteria. Controllers designed by deterministic and stochastic optimal control methodologies are compared to each other as well as a conventional controller via time-domain simulations of the ship, steering system, and seaway. The need for adaptivity of controller parameters in the face of changing ship and environmental conditions is established. An adaptive control system design is outlined for an autopilot design for online minimization of the chosen performance criterion for open seas coursekeeping.