A roll stabilization system for a monohull ship: modeling, identification, and adaptive control

In this paper some results regarding the implementation of an automatic roll reduction system for a new monohull ship are presented. To attenuate the roll due to the waves, two auxiliary automatically controlled wings are proposed. These auxiliary wings which are variably dipped into the water introduce a torque that reduces the oscillations of the ship. Dynamic models based on experimental data of the ship, of the hydraulic actuators, and of the disturbances due to the waves are computed, both from physical data and by using identification techniques from experimental measurements. Two different compensators for the roll effect have been designed. The first one was designed by using classical frequency domain techniques, whereas the second was an adaptive linear quadratic compensator. For this compensator, adaptation was performed by using a multilayer perceptron neural network. For the classical controller both simulations and experimental tests performed on the real ship have shown the capabilities of the proposed control system, while for the adaptive controller the results obtained revealed the superior performance that can be reached by using more sophisticated controllers.