State observation for quasi-linear uncertain systems by nested high-order sliding mode observer

The problem of observation of some classes of quasilinear uncertain systems is studied in the framework of unknown input observer theory. High-order sliding-mode observers are designed for the considered classes of systems. Necessary conditions for the convergence of the proposed observers are given in terms of restrictions on the system matrices. A new observation scheme, based on the error injection by high-order sliding-mode control, is proposed. Simulations confirm the theoretical results.