Thruster Allocation: Singularities and Filtering

Abstract The problem of determining the thrust and the direction of each of the n thruster devices of a ship given the desired forces and moment from the control law is discussed- In the case of rotatable azimuth thrusters, the existence of singular configurations where infinite thrust is required from the propulsion system to satisfy the control law is pointed out. The problems with singularities are solved by modifying the singular value decomposition. A filtering scheme is proposed to control the azimuth directions to reduce the wear and tear and to minimize the required thrust and power.