Adaptive global output feedback stabilisation of some non-minimum phase nonlinear uncertain systems

The output feedback stabilisation of some parameter-perturbed non-minimum phase nonlinear systems is considered. For such systems, it is shown that a robust global asymptotic stability can always be achieved via dynamic output feedback, if a global adaptive observer can be constructed and if the system can be rendered minimum phase with respect to a virtual output, which is a linear combination of state variables. This result generalises some existing approaches in the literature. A simulation example illustrates the effectiveness of the proposed method.