A New Framework of Disturbance Observer with Vidyasagar's Structure

Abstract

This paper proposes a novel two degree of freedom (TDOF) control structure: a combination of Vidyasagar's structure (VS) and the doubly coprime factorization based disturbance observer (DCFDOB). The DCFDOB-VS framework is aimed at providing a control structure and design procedure for a MIMO system with good characteristics of disturbance attenuation, tracking, and decoupling property. The structure can deal with stable/unstable and minimum phase/non-minimum phase plants. The advantage of the method is that two parameters can be designed for different purposes, independently. The parameter H stabilizes the system and improves tracking property. Once the parameter H has been designed, then the Q(Y) can be implemented via a parameter Q for rejecting disturbances and improving the system robustness.