Research On Output Feedback Stablization For Stochastic Nonlinear Time-delay Systems

A large number of uncertain(stochastic)phenomena exists in the actual dynamic system.In this case,using stochastic differential equation is necessary.Meanwhile,considering the existence of time delays in engineering systems,the research of stochastic time-delay system is a hotspot in the field of control theory in recent years.Firstly,for a class of stochastic nonlinear time-delay systems with strict feedback,considering the effect of time-delay,an observer is designed.After constructing an appropriate Lyapunov function,an observer-based controller is designed by backstepping method,which makes the closed-loop system asymptotically stable in probability.Secondly,considering the random disturbance in other cases,e.g.covariance unknown,the observer and adaptive controller are designed by using similar methods.The controller is independent of time delay,and the asymptotic stability of closed-loop system in probability can be guaranteed under the influence of time-delay in a certain range.Finally,considering the limitations of previous design methods based on the assumption of slow time-varying system,a new controller design method is proposed.It is designed by using the technique of domination method and Razumikhin theorem to make the closed-loop system globally asymptotically stable in the mean-square sense.