Universal Output-feedback Siso Controllers

It is proved in the paper that practically all known higher-order sliding controllers can be combined with recently developed 2-sliding-mode-based differentiators yielding universal output-feedback Single-Input-Single-Output (SISO) controllers. These controllers can be applied at least locally, whenever the system relative degree is known. The convergence is global, provided the system relative degree is permanent and few boundedness restrictions hold. No detailed mathematical model of the system is needed. The proposed output-feedback controller provides for the exact finite-time-convergent output tracking of real-time-given smooth signals if the output measurements are exact. Otherwise the tracking accuracy is proportional to the magnitude of the sampling noise. The control may be made arbitrarily smooth, thereby removing the chattering effect. The theoretical results are illustrated by computer simulation.