Nonlinear control of a subscale submarine in emergency ascent

Abstract

This paper presents a nonlinear parametric model and proof-of-concept motion control system for a scale model submarine undertaking an emergency ascent. An energy-based model is presented that represents the underactuated submarine in a non-neutrally buoyant state. This model is then used to synthesize a control law using Port-Hamiltonian theory and interconnection and damping assignment passivity-based control. Lyapunov analysis is used to demonstrate stability of the closed-loop system, and a simulation-based study is presented to demonstrate performance of the control law. The results demonstrate that a closed loop non-linear controller is able to improve the quality of emergency rise by automatically compensating for some parasitic effects in the hydrodynamics that can compromise ascent performance.