(A) study on robust gain scheduling in nonlinear systems with exogenous signal and time-delay in the input

Abstract

The dynamic behavior of practical process, in general, always changes according to the variation of the operating points as well as the exogenous signal. Thus, in this dissertation, a class of uncertain nonlinear systems driven by an exogenous signal is firstly considered. A robust gain scheduled controller is constructed to regulate the output despite of uncertainties and exogenous signal. In addition, when there is no information about uncertainties, a time-delay observer is introduced to combine with gain scheduling technique to guarantee the system`s robustness. Inspire of the fact that time-delay is inevitable in almost realistic engineering systems, various classes of nonlinear systems with an exogenous signal and time-delay in the input are investigated through this dissertation. Three gain scheduled controllers are suggested to deal with the tracking problem. The first one utilizes an approximated system and well known technique of singularly perturbed systems. Then, the second one takes advantages of the information from the exogenous signal to implement a gain scheduled controller to force the output to follow a reference signal asymptotically. Lastly, the third one exploits an adaptive sliding mode control with a reduction transformation to reject the effect of uncertainties, exogenous signal as well as time-delay in the input. Some illustrative examples are also provided to demonstrate the performance of these above proposed controllers.