On the observer assisted sliding mode creation: An active disturbance rejection approach

This article proposes the use of a high gain, Generalized Proportional Integral (GPI), observer for the accurate linear estimation of nonlinear endogenous, and exogenous, disturbance inputs affecting the creation of local sliding regimes, on a given sliding manifold, for Single-Input Single-Output (SISO) systems with limited control authority. Active, online, estimation, and cancelation, of state dependent and time-dependent disturbances, significantly contribute to reducing the required switching control amplitude needed to sustain a sliding regime. This method results in enhanced performance on the controlled variable. Illustrative simulation examples are presented which validate the proposed approach.