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This article investigates the finite‐time recoil control problem of deepwater drilling riser systems with nonlinear friction force, tension force and saturation input. For the friction force, a new approximation model based on radial basis function neural networks is presented, which not only can ensure a better approximation effect than the sine‐function type and exponential‐polynomial‐function type computational models, but also can be easily used for control design. Different from the existing linear optimal control methods, a neural‐network‐based adaptive backstepping control method is proposed to deal with the nonlinear friction and tension forces, which can achieve better recoil control responses. An auxiliary system combining with the change of coordinates is employed to compensate the saturation input effect. To prolong the average release interval of control input while preserving satisfied control performance, a new switched event‐triggered control (ETC) scheme is developed, in which the triggering conditions are switched between the fixed and relative thresholds based on the strength of control signal. With the event‐triggered controller, the practical finite‐time stability condition of recoil control system is derived and the Zeno behavior is avoided. Numerical results are given to show the advantages of the proposed methods in handling the model nonlinearities, finite‐time stability and ETC performance of riser‐tension systems. [ABSTRACT FROM AUTHOR]

In this note, the delay-dependent robust stability criteria for two classes of singular time-delay systems with norm-bounded uncertainties are investigated. First, without using model transformation and bounding technique for cross terms, an improved delay-dependent stability criterion for the nominal singular time-delay system is established in terms of strict linear matrix inequalities (LMIs). Then, based on this criterion, the delay-dependent robust stability criteria for two classes of uncertain singular time-delay systems are proposed, which ensure that the systems are regular, impulse free and asymptotically stable for all admissible uncertainties. Numerical examples are proposed to illustrate the less conservatism of the obtained results. Index Terms--Delay-dependent stability criteria, linear matrix inequality (LMI), norm-bounded uncertainty, singular time-delay systems.

This paper deals with the network-based modelling and reference model tracking control of four-wheel-independent-drive electric vehicles for turning purpose. First, a reference model is designed by adjusting its input to characterise the expected neutral turning of the vehicle. By considering event-triggered transmission and interval communication delays, the network-based tracking control system attaining vehicle turning is modelled as an interval input delay system, where the input delay is bounded by the bounds of communication delays and the sampling period. Second, a new delay-dependent bounded real lemma with less conservatism is derived by proposing a matrix-based binary quadratic convex method, constructing a discontinuous augmented Lyapunov–Krasovskii functional tailored based on second-order Bessel–Legendre inequality, and exploiting the relation among the upper bounds of input delay and interval communication delays, and the sampling period. Third, the network-based H ∞ tracking controller design result is further established by linear matrix inequalities. Finally, an example is provided to confirm the superiority of the analysis results and the effectiveness of control design. [ABSTRACT FROM AUTHOR]

In the above paper, an approach was proposed for the disturbance decoupling for the linear system. Some details in the proof of the sufficiency of Theorem 2 for the existence of the matrix F1 are omitted. In this note, we will give a detailed proof. Index Terms--Generalized inverse, orthogonal matrix transformation, stabilization.