NONLINEAR CONTROL VIA SLIDING MODES FOR UNCERTAIN NONLINEAR-SYSTEMS

The development of sliding mode controllers for nonlinear system descriptions is considered. Conditions for transformation and feedback linearization of a given nominal representation of an uncertain nonlinear system are well known. The ability of an augmenting sliding mode based control strategy to provide robustness to any unmodeled dynamics and parameter uncertainty is explored. A review of two existing design approaches is undertaken. A further method is proposed which builds upon the advantages of these current approaches whilst circumventing some of the deficiencies. Straightforward tutorial case studies are presented illustrating all three methods. It is shown that if the physical system does not lend itself to transformation to a required canonical form, transformation of a nearby system coupled with an appropriate sliding mode control design approach will yield robust performance.