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To guarantee the safety and reliability of drilling riser after emergency disconnection, it is significant to investigate and refrain recoil response of the riser. This paper deals with the problem of Takagi–Sugeno (T-S) fuzzy recoil dynamic modeling and optimal recoil control of nonlinear deepwater drilling riser systems subject to friction resistance of fluid discharge and platform heave motion. First, a nonlinear recoil control model of coupled riser-tensioner is proposed by taking the nonlinear top tension of tensioner into account. Then, a T-S fuzzy dynamic model of the riser-tensioner system is established to approximate the original nonlinear one by using fuzzy modeling scheme. Third, an augmented T-S fuzzy model of riser system is proposed, where the linear exosystem model of friction resistance and platform heave motion is utilized. Fourth, a finite-time fuzzy optimal recoil controller is designed to suppress the recoil response of the riser, the existence and design algorithm of the fuzzy optimal recoil controller are derived. Simulation results demonstrate that the nonlinear recoil model is more accurate than the existing linear one to describe the recoil characteristics of the riser, and the fuzzy optimal recoil controllers are effective to reduce recoil responses and guarantee the safety of the riser significantly. • A nonlinear recoil dynamic model of coupled riser-tensioner is proposed by considering the nonlinear tension. • An augmented T-S fuzzy dynamical model of riser system is developed, where an exosystem of friction resistance is utilized. • Finite-time fuzzy optimal recoil controllers are designed to suppress the recoil response of the riser. • The fuzzy optimal recoil controllers are effective to reduce recoil responses and guarantee the safety of the riser. [ABSTRACT FROM AUTHOR]

This study addresses discrete dynamic modelling and the optimal recoil control problem of deepwater drilling riser systems subject to the friction resistance of fluid discharge and platform heave motion. First, a discrete-time exosystem model for friction resistance of drilling fluid discharge is developed; then, a discrete-time dynamic model of platform heave motion is established. Third, a finite-time discrete optimal recoil controller with feedforward compensation mechanisms was designed. The optimal recoil controller gains can be obtained by iteratively solving discrete equations. The simulation results show that under the discrete feedforward and feedback optimal recoil controller and pure feedback optimal recoil controller, the recoil movements of the riser system are significantly restrained. Moreover, the former is more effective than the latter at resisting the riser recoil response. • A discrete-time exosystem model of the friction resistance induced by drilling fluid discharge on the riser is proposed. • A discrete-time dynamic model of irregular heave motion of drilling platform is established. • A discrete-time recoil control model of the drilling riser system subject to viscous resistance of fluid discharge and platform heave motion is developed. • A finite-timediscrete optimal recoil control scheme with feedforward mechanism is designed to suppress the recoil response of the riser. [ABSTRACT FROM AUTHOR]

This paper deals with the adaptive learning based recoil suppression control problem of deepwater drilling riser systems subject to parametric perturbations, platform heave motion, and friction resistance force of drilling fluid discharge. First, a stochastic configuration network based approximator is presented to predict the friction resistance force of drilling fluid discharge. Then, model reference adaptive learning recoil controllers are developed for the drilling riser system, and the existence condition and supporting algorithm are provided. Simulation results show that: (i) the designed stochastic configuration network approximator is efficient to predict the friction resistance of drilling fluid discharge on the riser; (ii) the presented model reference adaptive learning recoil controllers are effective to restrain the recoil response of the riser; (iii) compared with the existing recoil controllers, which are all based on the exact dynamic recoil control models, the model reference adaptive learning recoil controllers proposed in this paper are no longer constrained by the accuracy of recoil model; (iv) the model reference adaptive learning recoil controllers are more robust than the existing ones to the unmodeled dynamics, systematic uncertainty, and parametric perturbations, and have better transient performance of system thereby guaranteeing the safety of the drilling riser systems effectively. • A learning-based friction force predictor of drilling fluid discharge is designed. • Model reference adaptive learning recoil controllers are proposed for riser systems. • Adaptive recoil controllers are robust to unmodeled system dynamics and disturbances. [ABSTRACT FROM AUTHOR]

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. • Static output feedback recoil controllers with memory (OFRCMs) are designed for a drilling riser-tensioner system. • To design feasible OFRCMs, velocity signal of the first mass block of the riser-tensioner system is indispensable. • The designed OFRCMs provide more implementation options and practically better than existing recoil controllers. [ABSTRACT FROM AUTHOR]

This paper deals with the observer-based dynamic optimal recoil controller design of a deepwater drilling riser system subject to friction force of fluid discharge and platform heave motion. First, by using exponential and polynomial functions conjunctively, a novel nonlinear computational model of the friction force is presented. Then, a linear system model is developed to describe dynamic characteristics of the friction force. Third, by using feedforward mechanisms and internal model principle jointly, a dynamic optimal recoil control scheme is proposed for the riser, where the feedforward mechanism is designed to compensate the friction force of fluid discharge, and the internal model principle is introduced to reject platform heave motion. The conditions of existence and uniqueness of a dynamic optimal recoil controller of the riser are developed. Fourth, a friction force observer is designed to solve the physically realizable problem of the recoil controller. Simulation results show that under the observer-based dynamic optimal recoil controller, the recoil of the riser can be attenuated significantly, and zero steady state errors of the riser can be guaranteed. In addition, from the perspective of achieving steady performance of the riser, the designed dynamic optimal recoil control scheme outperforms existing linear quadratic optimal control schemes. • An exponential-polynomial type friction force model of fluid discharge is developed.. • An augmented coupling riser-tensioner recoil control system is presented. • An observer-based dynamic optimal recoil controller with feedforward is designed. • The recoil controller can guarantee a zero steady–state error of the riser system. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of dynamic modeling and the optimal recoil control of a deepwater drilling riser system subject to the friction force of drilling fluid discharge. First, based on the whole fluid column model of the friction force and the curve fitting method, a linear exosystem model is established to describe the dynamic properties of the friction force, where the friction force of drilling fluid discharge is formulated as an output of the exosystem. Then a recoil dynamic model of the drilling riser in the event of emergency disconnection is proposed to describe the recoil response characteristics. Third, an optimal recoil control scheme with discharge feedforward compensation is developed to refrain the recoil response of the riser system. The existence and uniqueness conditions of the optimal recoil controller are derived, and the gain matrices of the controller can be obtained by solving an algebraic Riccati equation and a Sylvester equation. It is found through simulation results that the proposed optimal recoil controller with feedforward compensation can reduce recoil response of the riser system significantly. Moreover, the proposed controller outperforms the existing optimal recoil control scheme in the sense of the quadratic performance indices of the riser system. • An exosystem model of fluid discharge friction resistance on the riser is developed. • An optimal recoil control scheme with feedforward mechanisms is proposed. • The proposed scheme is effective to suppress recoil response of the riser system. [ABSTRACT FROM AUTHOR]