ROBUST INPUT-OUTPUT FEEDBACK LINEARIZATION

To make input-output feedback linearization a practical and systematic design methodology for single-input nonlinear systems, two problems n eed to be addressed. One is to handle systematically the difficulties associated with the internal dynamics or zero-dynamics when the relati ve degree is less than the system order. The other is to account for t he effect of model uncertainties in the successive differentiations of the output of interest. While the first problem has recently received considerable attention, the second has been largely unexplored. This paper represents a preliminary study of a systematic methodology to ac count robustly for parametric uncertainties in the original system mod el. The approach is based on combining sliding control ideas with the recursive construction of a closed-loop Lyapunov function, and is illu strated with a simple example.