Global robust output tracking control for a class of uncertain cascaded nonlinear systems

This paper focuses on the global robust output tracking control for a class of uncertain cascaded nonlinear systems. Using only the measured output, we present a dynamic output feedback λ-tracking control scheme in a recursive method. Without the assistance of some kind of high-gain observers, we employ a reduced-order observer to rebuild the unmeasured states. The dynamic adaptation switching mechanism plays a key role in achieving the output λ-tracking. It is shown that the designed λ-tracker guarantees the system output track any desired reference signal with prescribed accuracy, and keep all signals in the closed-loop system globally bounded. A chaos control application in the fourth-order generalized Lorenz systems demonstrates the efficacy of the proposed control strategy.