A passive output feedback controller with wave filter for marine vehicles

An output feedback controller with a wave filter for regulation of nonlinea r marine vehicles is derived. Only measurements of position and attitude ar e needed. Asymptotic stability for the position and attitude around the des ired values, and the velocity about zero is proven by applying Lyapunov sta bility analysis. Even though the wave filter in this paper has a notch filt er structure, it is incorporated in the controller such that the system fro m the vehicle's velocity to the control input is passive. This is opposed t o conventional notch filters which are usually designed separately from the controller itself, possibly complicating the stability analysis. Finally, a simulation study of a ship illustrates the design procedure of the contro ller. (C) 1998 John Wiley & Sons, Ltd.