Path following Control of an Underactuated Catamaran for Recovery Maneuvers

Abstract

This paper focuses on the autonomous recovery maneuvers of an unknown underactuated practical catamaran, which returns to its initial position corresponding to the man overboard (MOB) by simply adjusting the rate of turn. This paper investigates the completion of model-based path following control for not only the traditional Williamson turn, but also complex recovery routes under time-varying disturbances. The main difficulty of model-based path following control for predicting the hydrodynamic derivatives of a practical catamaran was solved by the approximated calculation of a diagonal matrix. The second key problem of differential calculation for an underactuated model in the case of complex reference trajectories under severe disturbances was investigated. Even though this paper employs a diagonal matrix with unknown nonlinear terms, the experimental test using a small craft with payloads by remote control demonstrated the sway force per yaw moment in turning cases. Adaptive backstepping mechanisms with unknown parameters were proven by the Lyapunov theory as well as the passive-boundedness of the sway dynamics, guaranteeing the stability of sway motion in the case of unavailable sway control. The effectiveness of the algorithms of the guiding concept and error dynamics is demonstrated by the numerical simulations.

Ship Roll Prediction and Parameter Identification under Unknown Ocean Disturbances

“…The idea of backstepping is to recursively design a controller by considering some of the state variables as "virtual controls" and creating intermediate control laws for them [24]. This method is one of the proper nonlinear controllers for regulating the desired ship motions [25][26]. By adding the actuation input u to a ship model [27][28], the complete control system represents a forced rolling system with active control input by…”