Disturbance Rejection and Control System Design Using $\lbrace 1\rbrace$-Inverse-Based Equivalent-Input-Disturbance Approach

Abstract

This article develops an improved equivalent-input-disturbance (EID) approach that rejects disturbances for a plant. A control system based on the approach includes an improved EID estimator, which is newly devised using a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lbrace 1\rbrace$</tex-math></inline-formula> inverse of the plant input matrix. Compared with a conventional EID estimator, the improved EID estimator has an additional free matrix. This free matrix enables the control system to improve the disturbance rejection performance but not increase the configuration complexity. An analysis of the control system explains how the free matrix improves the disturbance rejection performance. The experiments of a posture control system for a Stewart platform demonstrate the validity of the approach.