Dynamic mooring-forces allocation in dynamic ship positioning

The design of a dynamic positioning system for a multiplymoored vessel with active winches and thrusters is presented. The proposed positioning system is based on the Kalman filter and linear optimal control. Its peculiarity is that it contains a scheme which allocates dynamically the control forces between moorings and thrusters. The allocation policy tries to minimize the energy of the control by maintaining the average propeller thrust near to zero. The efficacy of the scheme is illustrated by numerical simulations.