OPTIMAL THRUST ALLOCATION FOR MARINE VESSELS

This paper presents a new thrust-allocation scheme which significantly reduces the fuel consumption for dynamic positioning of ships when ro tatable azimuth thrusters are used. Thrust allocation is the problem o f determining the thrust and the direction of each of the n thruster d evices of a ship, given the desired forces and moment from the control law. The problem of singular configurations is pointed out and solved by using a modification of the singular-value decomposition. A filter ing scheme is proposed to control the azimuth directions to reduce the wear and tear, and to minimize the required thrust and power in a gen eral manner, allowing the enabling and disabling of thrusters. Both ne w theory and full-scale sea trials are presented. Copyright (C) 1997 E lsevier Science Ltd.