Robust Adaptive Control Algorithm For Nonlinear Systems Based On Smart Material Actuators

The position of precision manufacturing is becoming more and more prominent in the field of modern advanced manufacturing,and the applications of all kinds of smart material drivers in high precision cutting/machining,micro operation and micro assembly have been paid more and more attention.However,the intrinsic hysteresis nonlinearity is inherent in the smart material driver,and the hysteresis has the characteristics of undifferentiability,multi value mapping,nonsmoothness and memory,which brings great challenge to the nonlinear control system with smart material driver,and seriously restricts the smart material driver in the advanced manufacturing field.On the other hand,in the whole control system,the existence of time delay is also an unavoidable problem.Therefore,the study of control algorithm for cascade nonlinear systems with hysteresis and time-delay is of great theoretical significance and application value.In this paper,two kinds of strict feedback nonlinear systems with hysteresis input are used,the adaptive dynamic surface technology and the backstepping control technology are used to design the control scheme,and the stability analysis is carried out.Finally,the experimental simulation is carried out.The main research contents and innovation points are as follows:1)An adaptive dynamic surface control scheme based on fuzzy approximator is proposed for a class of unknown time-delay nonlinear systems with asymmetrical hysteresis input.The characteristic of the proposed control scheme is that by combining the approximation property of the fuzzy logic system and the famous finite cover theorem,the coupling time delay problem in the system is dealt with.The traditional Krasovskii function method is abandoned,the restrictive condition for the time delay function is removed,and there is no construction of the asymmetric shifted Prandtl Ishlinskii model.The proposed adaptive fuzzy dynamic surface control scheme can compensate the hysteresis nonlinearity described by the ASPI model in the case of the unknown density function of the type inverse and ASPI hysteresis model(by on-line estimation compensation and hysteresis).The stability analysis can guarantee the closed-loop system by the initialization technique.All signals are semi globally uniformly bounded and can converge arbitrarily to a residual set.2)For a class of hysteresis nonlinear systems described by the Prandtl-Ishlinskii(PI)model,an input quantization adaptive output feedback control scheme based on fuzzy logic approximator is proposed.In order to deal with the strong nonlinearity caused by the quantizer,a new linear time-varying quantizer degradation scheme can be introduced to change the parameters of the quantizer arbitrarily during the operation.By using the hysteresis inverse compensator,the effect of hysteresis on the control precision of the piezoelectric ceramic actuator can be greatly reduced;the fuzzy logic system is used.The approximation property of the system and the design of high gain observer are used to approximate the unknown functions in the system and the unknown state in the estimation system.No matter how the quantizer quantifies,the proposed control scheme can guarantee the global boundedness of all the signals in the closed loop system,and the norm of the tracking error can be obtained by the initialization technique.