Global asymptotic stabilization of an underwater vehicle using internal rotors

We derive a feedback control law that uses internal rotors to globally stabilize steady translation of an underwater vehicle that is subject to fluid drag as well as conservative rigid body and fluid forces. This result extends our previous work on asymptotic stabilization of the system where physical dissipation was neglected. Our stabilizing control laws consist of two terms: the first term addresses the conservative part of the system by shaping energy to yield Lyapunov stability, and the second term adds dissipation to ensure asymptotic stability to the motion of interest. The Lyapunov function must be suitably modified in the second step since fluid drag destroys conservation of momentum, and the feedback-controlled dissipation must be carefully designed to dominate the possibly destabilizing fluid drag