Zong-Yao Sun

Continuous global stabilisation of high-order time-delay nonlinear systems++

This paper studies the global stabilisation problem for a class of high-order nonlinear systems with multiple time delays. A distinct property of the systems to be investigated is that powers on the upper bound restrictions of nonlinearities are allowed to take values on a continuous interval. By introducing the sign functions and using the generalised method of adding a power integrator, this paper successfully designs a continuous global state-feedback controller independent of time delays. Moreover, a novel Lyapunov–Krasovskii functional is constructed to prove the globally asymptotic stability of the resulting closed-loop system.

A unified time-varying feedback approach and its applications in adaptive stabilization of high-order uncertain nonlinear systems

We are concerned with two key problems of adaptive control design: one is to find the feasible conditions and the valid boundary of the time-varying feedback scheme; another one lies in the improved generalization of the homogeneous idea in the global adaptive stabilization of high-order uncertain nonlinear systems. The distinguished feature of the system to be investigated is the serious coexistence between unknown time-varying parameters and unknown time-varying control coefficients. Design procedures of the continuous controller are provided based on the sign function technique and the delicate search of the time-varying function and a Lyapunov function. Finally, the control of uncertain single-link robotic manipulator demonstrates the application of design scheme.

Global stabilisation of high-order nonlinear systems with multiple time delays

This paper focuses on the stabilisation for a class of high-order nonlinear systems with multiple time delays. Growth restriction on system nonlinearities is further relaxed. Design procedures of a continuous controller are provided by the method of adding a power integrator, and the stability of the resulting closed-loop system is rigorously proven with the help of the elegant choice of a Lyapunov–Krasovskii functional. Finally, a simulation example is provided to demonstrate the validness of the proposed approach.

Global continuous output-feedback stabilization for a class of high-order nonlinear systems with multiple time delays

Abstract This paper addresses the global output-feedback stabilization for a class of high-order nonlinear systems with multiple time delays. A distinct property of the systems to be investigated is that powers on the upper bound restrictions of nonlinearities are allowed to take values on a continuous interval, another remarkable one rests with the existence of multiple time delays in growth conditions. By introducing a combined method of sign function, homogeneous domination and adding a power integrator, an output-feedback controller based on Lyapunov-Krasviskii theorem is designed recursively to guarantee the equilibrium of the closed-loop system globally uniformly asymptotically stable.

A new approach to fast global finite-time stabilization of high-order nonlinear system

Abstract This paper is concerned with the improvement of finite-time stability theorem and its application in stabilizing a class of high-order nonlinear systems globally. The novel control strategy unifies the construction of Lyapunov functions, which are used to deal with high-order and low-order nonlinear growth rates separately in the existing results. Convergent time is shortened greatly without requiring large control effort, but it suffers long period from traditional finite-time stabilization scheme when initial state is far away from the origin. Finally, two simulation examples including a practical one are presented to illustrate the efficiency of the proposed strategy.

Adaptive disturbance attenuation for generalized high-order uncertain nonlinear systems

Abstract This paper investigates the problem of adaptive disturbance attenuation for a class of generalized high-order uncertain nonlinear systems. The control strategy is on the basis of continuous domination and delicate adaptive technique, and it can cope with serious coexistence among uncertainties, including time-varying control coefficients which have unknown upper and lower bounds, nonlinear parameters and external disturbances. Adaptive state-feedback controller is one-dimensional irrespective of the number of unknown parameters, and its performance is evaluated in terms of L 2 - L 2 p gain.

Output feedback stabilization for high-order uncertain feedforward time-delay nonlinear systems

Abstract This paper addresses the output feedback stabilization problem for a class of high-order uncertain feedforward time-delay nonlinear systems. Under a weaken assumption that the powers of nonlinear functions are relaxed to an interval, the new control strategy implanting sign functions into homogeneous domination idea and observer construction allows time-varying delays to coexist in system state and control input. With the aid of delicate selections of design parameters, observer gains and Lyapunov–Krasovskii functionals, it is shown that the closed-loop system is globally asymptotically stable.

Output tracking control for generalised high-order nonlinear system with serious uncertainties

ABSTRACTThis paper focuses on the problem of output tracking control for a class of generalised high-order uncertain nonlinear systems. Serious uncertainties are composed of unknown high-order terms, unknown nonlinear functions and the signal to be tracked. The new feedback scheme guarantees that the tracking error belongs to a prescribed small neighbourhood of the origin in finite time. Design procedures are presented by combining improved adding a power integrator method with the recursive construction. As an application, the control methodology is used in the tracking control of the mass-spring mechanical system.

Output feedback control for a class of high-order nonholonomic systems with complicated nonlinearity and time-varying delay

Abstract This paper considers the output feedback control problem for high-order nonholonomic time-delay system. Remarkably, the studied system allows the polynomial time-delay growing conditions. Moreover, the applicable power ranges of nonlinear drift and diffusion terms are further relaxed to be a interval rather than a fix point. By choosing a new Lyapunov–Krasovskii (L–K) functional, and by modifying the adding a power integrator method, a delay-independent output feedback controller is designed such that the system is globally asymptotically stable. A simulation example is given to show the validity of the proposed theory.

Lateral motion stability control of electric vehicle via sampled-data state feedback by almost disturbance decoupling

ABSTRACT The paper presents a lateral motion stability control method for electric vehicle (EV) driven by four in-wheel motors, which considers time-variable vehicle speed and uncertain disturbance caused by external factors. First, an EV lateral motion dynamics tracking control model is presented. Then in order to deal with the uncertain disturbance in the lateral motion model, an almost disturbance decoupling method using sampled-data state feedback is proposed. Third, a sampled-data state feedback controller is constructed based on the state feedback domination approach. The proposed controller can attenuate the disturbances’ effect on the output to an arbitrary degree of accuracy. Simulation and test results under different vehicle speeds show the effectiveness of the control method.