Recoil suppression of deepwater drilling riser systems via static output feedback control with memory

In the dangerous ocean situations, the deepwater drilling riser needs evacuate emergently to guarantee the safety of the structures. The bottom equipment of the lower marine riser package should be disconnected from the blowout preventer timely. In this case, the recoil response of the riser occurs, which may lead to potential safety risks of the structure. This paper deals with the recoil suppression control problem of a deepwater drilling riser system via static output feedback recoil control scheme with memory. First, for the riser-tensioner system subject to the friction resistance of drilling discharge and the heave motion of platform, a static output feedback recoil controller with both current and delayed output signals of the system is proposed. Then, the existence conditions and design algorithm of the static output feedback recoil controller are derived. The gain matrices of the recoil controller can be obtained by solving linear matrices inequalities. It is found through simulation results that (i) the static output feedback recoil controllers with and without memory are effective to reduce the recoil responses of the riser; and (ii) to design the applicable output feedback recoil controllers, the displacement and velocity signals of the first mass block of the riser are required, and specifically, the velocity signal of the first mass block is indispensable; and (iii) the output feedback recoil controllers with memory provide more implementation options, and practically better than the ones without memory and some existing full state feedback recoil controllers.