Stabilization Of Uncertain/time-delay Nonlinear Systems Under Different Constraint Conditions

As we all know,many practical engineering applications exist in the form of nonlinear systems,so the control design of nonlinear systems has gradually become a hot issue in the field of control theory.However,in reality life,due to the limitations of measurement methods and other factors,there will be time delays and other phenomena in the control systems.In many practical applications,the systems are often accompanied by various forms of constraints,such as state constraints,output constraints,input constraints,and so on.The emergence of these problems will make the control design of the system different.Therefore,in the framework of nonlinear systems,it becomes more meaningful to study the system with time-delay and constraints.The research of this article mainly includes the following two parts:?.Research on fast finite-time adaptive stabilization of higher-order nonlinear systems with an asymmetric output constraintThis part is concerned with two essential problems in adaptive control.The first is to establish a fast finite-time control scheme for high-order uncertain nonlinear systems with inherent nonlinearities and an asymmetric output constraint,and the second is to improve the stability criteria in the presence of the constraint and unknown parameters.A continuous adaptive controller is constructed by utilizing a new barrier function and a serial of nonnegative integral functions equipped with sign functions,which guarantees that the output is restricted in a prescribed region and the state converges to zero in a faster speed compared to some traditional finite-time stabilizers.Unlike some existing control schemes developed for systems with the output constraint,the proposed method unifies finite-time control design in dealing with both constrained and unconstrained systems for the first time by taking the structure of the high-order system into consideration.Finally,a simulation example confirms the effectiveness of theoretical results.?.Global stabilization of lower-triangular nonlinear systems with delayed input and delayed stateThis part addresses the problem of the global state feedback stabilization for a class of lower-triangular nonlinear systems whose states and input are perturbed by time-delay simultaneously.Quite different from upper-triangular systems,the presence of delayed input leads to the serious dependency of the stabilizer upon the size of the delays and the failed compensation of delayed states in such situation.The remarkable feature of the proposed method lies in the fact that it makes possible to achieve the stabilizing controller with the help of a simple inductive design and an integral Lyapunov function.Finally,a simulation example confirms the effectiveness of theoretical results.