Global Stabilization of Marine Risers with Varying Tension and Rotational Inertia

Abstract

This paper presents a design of boundary controllers implemented at the top end for global stabilization of a marine riser under environmental loadings. Based on the energy approach, nonlinear partial differential equations of motion including varying tension and rotational inertia for the riser are derived. The Lyapunov direct method is used as a design tool to design the boundary controller comprising of forces and moments to compensate rotational effects. It is shown that the proposed boundary controllers can effectively reduce the riser's vibrations. Proof of the existence and uniqueness of the solutions of closed loop systems are provided based on the Galerkin approximation method. Stability analysis of the closed-loop system is performed using the Lyapunov direct method. Numerical simulations illustrate the results.