Adaptive Control Design For Uncertain Nonlinear Systems With Small Delay

The nonlinear and time delay are widespread in the actual control system,such as communication system,power system,network transmission system,machinery transmission system and the process of metallurgy industry,and affects the performance and stability of the system,therefore,the research of nonlinear control systems with time delay is of great importance in view of the above consideration,this dissertation studies a class of uncertain nonlinear systems with short delay adaptive control design problem in this paper,the main work is as follows(1)An adaptive tracking control problem is addressed for a class of uncertain nonlinear systems with input delay and perturbations.To design the desired adaptive controller,Pade approximation approach is introduced to handle the problem from the input delay.In addition,to avoid the problem from "explosion of complexity ' existing in the conventional backstepping design,a dynamic surface control(DSC)method is presented by employing a nonlinear filter.Then,a new adaptive controller with a simple structure is established.Under the proposed controller,all the closed-loop signals remain semiglobally bounded,and especially the system output can follow the given reference signal asymptotically.(2)This dissertation considers the finite-time adaptive neural networks DSC problem for the nonstrict feedback systems involving input delay.Different from the existing results on the uncertain nonlinear systems with nonstrict feedback form,the input delay phenomenon is taken into account.And in order to avoid the problem of"complexity of explosion" in the backstepping design process,the DSC technology with nonlinear filter is introduced to simplify the structure of the adaptive neural network controller.Neural networks are used to approximate the unknown system functions online and the Pade approximation method is employed to deal with the input delay problem.Under the developed control strategy,all the closed-loop signals are semiglobal bounded and the tracking error converges to a sufficiently small area near the origin in a finite time.Finally,the simulation results are given to verify the effectiveness of the proposed control schemes...