Multiple-surface sliding control of a class of uncertain nonlinear systems

We develop a 'multiple-surface' sliding control for a class of single-input single-output nonlinear systems whose uncertainties do not satisfy the standard matching condition. A coordinate dependence condition on the uncertainty bound is assumed. A 'computed normal form' is defined to handle such uncertainties instead of the normal form used in conventional input-output linearization. A control algorithm which can be applied to global tracking problems has been developed and evaluated for a benchmark example.