Wenting Zha

Finite-time stabilization for a class of stochastic nonlinear systems via output feedback.

This paper investigates the problem of global finite-time stabilization in probability for a class of stochastic nonlinear systems. The drift and diffusion terms satisfy lower-triangular or upper-triangular homogeneous growth conditions. By adding one power integrator technique, an output feedback controller is first designed for the nominal system without perturbing nonlinearities. Based on homogeneous domination approach and stochastic finite-time stability theorem, it is proved that the solution of the closed-loop system will converge to the origin in finite time and stay at the origin thereafter with probability one. Two simulation examples are presented to illustrate the effectiveness of the proposed design procedure.

Global adaptive output feedback control for a class of nonlinear time-delay systems

This paper addresses the problem of global output feedback control for a class of nonlinear time-delay systems. The nonlinearities are dominated by a triangular form satisfying linear growth condition in the unmeasurable states with an unknown growth rate. With a change of coordinates, a linear-like controller is constructed, which avoids the repeated derivatives of the nonlinearities depending on the observer states and the dynamic gain in backstepping approach and therefore, simplifies the design procedure. Using the idea of universal control, we explicitly construct a universal-type adaptive output feedback controller which globally regulates all the states of the nonlinear time-delay systems.

Global output feedback control for a class of high-order feedforward nonlinear systems with input delay

This paper investigates the problem of output feedback stabilization for a class of high-order feedforward nonlinear systems with time-varying input delay. First, a scaling gain is introduced into the system under a set of coordinate transformations. Then, the authors construct an observer and controller to make the nominal system globally asymptotically stable. Based on homogeneous domination approach and Lyapunov-Krasovskii functional, it is shown that the closed-loop system can be rendered globally asymptotically stable by the scaling gain. Finally, two simulation examples are provided to illustrate the effectiveness of the proposed scheme.

Finite-time state-feedback control for a class of stochastic high-order nonlinear systems

This paper discusses the problem of global finite-time stabilization in probability for a class of stochastic high-order nonlinear systems whose drift and diffusion terms satisfy lower-triangular growth conditions. By adopting adding one power integrator technique and constructing twice continuous differential Lyapunov functions, a continuous state-feedback controller is recursively designed. Based on stochastic finite-time stability theorem, it is proved that the solution of the closed-loop system is finite-time stable in probability. Several simulation examples are given to illustrate the effectiveness of the proposed design procedure.

Decentralized global output feedback stabilization for a class of uncertain nonlinear systems

This paper considers the problem of decentralized global stabilization via output feedback for a class of uncertain nonlinear systems with unknown output functions, in which the nonlinear terms are interconnected by unmeasurable states and the inputs of each subsystem. First, we design the controller for each nominal subsystem without the perturbing nonlinearities. Then, we apply the homogeneous domination approach to design scaled homogeneous observers and controllers with an appropriate choice of gain to render the nonlinear system globally asymptotically stable. Finally, two simulation examples are shown to illustrate the effectiveness of the proposed scheme.

Robust control for a class of nonlinear systems with unknown measurement drifts

This paper addresses the problem of designing a robust controller for a class of nonlinear systems whose states cannot be precisely measured caused by the unknown drifts in the powers of the measurement functions. By adopting the concept of homogeneity with monotone degrees and revamping the technique of adding a power integrator, a new design procedure is introduced to recursively construct a generalized homogeneous controller with monotone degrees as well as a Lyapunov function with unknown parameters. The proposed controller is able to globally stabilize a family of nonlinear systems with different measurement drifts whose bounds can be determined by solving an optimization problem.

Semi-global decentralised output feedback stabilisation for a class of uncertain nonlinear systems

This paper discusses the problem of semi-global decentralised output feedback control for a class of uncertain nonlinear systems. Based on the ideas of the homogeneous systems theory and the adding a power integrator technique, we first design a homogeneous observer and an output feedback control law for each nominal subsystem without the nonlinearities. Then, using the homogeneous domination approach, we relax the linear growth condition to a polynomial one and construct decentralised stabilisers to render the nonlinear system semi-globally asymptotically stable. Two simulation examples are provided to show the effectiveness of the control scheme.

Global Adaptive Finite-Time Control for Stochastic Nonlinear Systems via State Feedback

This paper discusses the problem of global adaptive finite-time control for a class of stochastic nonlinear systems with parametric uncertainty. Under the assumption that the drift and diffusion terms satisfy lower-triangular growth conditions, a continuous adaptive controller is designed based on the adding one power integrator technique and parameter separation principle. By constructing an adaptive law to counteract the effects of uncertain parameters, it is proved that system states can be regulated to the origin almost surely in a finite time. Two simulation examples are given to demonstrate the effectiveness of the proposed control procedure.

Dynamic linear controller design for a class of high-order nonlinear systems via state-feedback

The objective of this paper is to address the linear state-feedback control problem for a family of high-order uncertain nonlinear systems. Based on the adding a power integrator technique, the authors recursively construct a linear controller with dynamic gains, which can be used to deal with the uncertain nonlinear terms and simplify the controller structure. Moreover, it is proved that the proposed control law can globally regulate system states to the origin and guarantee the boundedness of all the signals of the closed-loop system as well. Finally, a simulation example is presented with some comparison with the existing result so as to demonstrate the effectiveness of the proposed design scheme.

Global control for a class of planar stochastic nonlinear systems with unknown output gain

This paper addresses the problem of global asymptotical stabilization via output feedback for a class of planar stochastic nonlinear systems whose output gain is not precisely known. We first design an observer and use the estimated states to construct a controller to globally stabilize the nominal linear system without considering perturbing nonlinearities. Then we apply the homogeneous domination approach to design a homogeneous observer and controller with an appropriate choice of scaling gain to render the planar stochastic nonlinear system globally asymptotically stable in probability.