Modeling and control of a flexible riser with application to marine installation

This paper investigates the control problem of a marine riser installation system. The riser installation system consisting of a vessel, a flexible riser, a subsea payload is modeled as a distributed parameter system with one partial differential equation (PDE) and four ordinary differential equations (ODEs). Based on the Lyapunov's direct method, robust adaptive boundary control is proposed at the top and bottom boundary of the riser to position the subsea payload to the desired set-point and suppress the riser's vibration. With the proposed control, uniform boundedness of the steady state error between the boundary payload and the desired position is achieved by suitably choosing the design parameters. Numerical simulations are presented for demonstrating the effectiveness of the proposed control.