Composite control of a tethered underwater flight vehicle

Abstract For tethered underwater vehicles, the behaviour of the feedback autopilots which are developed for un-tethered vehicles are subject to the tether effects. Therefore it is desirable to apply a composite scheme for the control of tethered underwater vehicles: while the feedback controller deals with the vehicle dynamics, a feed-forward compensator cancels the tether effects. This paper presents such a study for the control of a tethered underwater flight vehicle. The LMI-based H∞ approach was applied to develop the reduced-order feedback autopilots for the un-tethered vehicle, and the tether (communication cable) effects were reduced by the feed-forward compensator. Nonlinear simulation results showed the effectiveness of the scheme.