Robust control synthesis for uncertain nonlinear time-varying systems with time delays

This paper presents a design method for output tracking control of a class of single-input single-output (SISO) nonlinear time-varying systems in the presence of modeling errors and time delays. A robust control strategy containing a corrected time-varying feedforward/state feedback and a simple online tuning parameter, which is based on the nonlinear Smith-type predictors and high feedback gains in the inner and outer loops, is developed. The presented control strategy can guarantee that the resulting states of the closed-loop system are uniformly ultimately bounded. We illustrate our controller framework and results by an example of chemical reactor control.