Analytical solution to motion planning and modal-based tracking control for dynamic positioning of subsea equipment

Abstract

One of the challenges of the installation of subsea equipment is the precise positioning of the equipment in a desired location on the seabed. This positioning procedure is still commonly performed manually by an operator. This article presents a trajectory tracking control system design for the positioning of a subsea equipment. This work will be done in two stages. First, a motion planning for dynamic positioning system of platform is presented. For this, an analytical solution of motion equation of the riser, which is modeled as a damped cable, is detailed. This analytical solution when compared to numerical solutions has the advantage of generating more precise and smooth trajectories for the system input and output. Second, we propose a tracking control system to ensure that the subsea equipment follows the desired trajectory in the presence of disturbances. More precisely, a linear state-feedback control law is proposed using a reduced model, which is obtained from a modal reduction with delay insertion. This delay insertion provides a high precision low order model. This fact highly increase the robustness of the control system to the measurement noise. Numerical simulations and experimental tests are presented to evaluated the proposed control strategy.