Reliability of disturbance rejection control based on the geometrical disturbance decoupling

Abstract

In this note, a reliable disturbance decoupled control system based on the geometrical technique is proposed. For this purpose, first, the conditions for nominal disturbance detection and rejection is introduced by using invariant subspaces. Then, the fragility issue of the controller/observer is addressed with appropriate H∞ constraints in the form of some linear matrix inequalities (LMIs). In contrast to conventional pole placement method suitable for systems by neglecting sources of uncertainty, in the presented method, the disturbance rejection problem reduces to a quadratic stability problem. It is observed that the proposed method has a better attenuation performance than classical observer-based non-fragile controller.

Robust Linear Output Regulation Using Extended State Observer

“…For compensation of the disturbances without known frequency characteristics-represented by the signal ( )-an ESO is designed. Note that, trivially, based on the matched condition, the unstructured disturbance is assumed to belong to the range space of ; otherwise the transfer function from disturbance to the output of interest cannot be set to null (see the geometrical approach proposed in [27]). Considering the composite system (6), the following ESO is proposed:…”

“…Additionally, to examine the effect of disturbance rejection on regulating the distance coordinate , we consider system (27) perturbed by the disturbance cancellation erroṙ…”