A new solution for the robust control problem of non-minimum phase systems using disturbance observer

Authors

Emre Sariyildiz, University of WollongongFollow
Kouhei Ohnishi, Keio University

RIS ID

115176

Publication Details

Sariyildiz, E. & Ohnishi, K. (2013). A new solution for the robust control problem of non-minimum phase systems using disturbance observer. 2013 IEEE International Conference on Mechatronics (ICM) (pp. 46-51). United States: IEEE.

Abstract

Plants, which have Right Half Plane (RHP) zero(s), are called as non-minimum phase systems due to their specific phase response characteristics. They have several constraints, such as bandwidth limitation, achievable sensitivity reduction etc., in the design of feedback control systems. Furthermore, the conventional Disturbance Observer (DOB) cannot be directly applied to the non-minimum phase systems due to internal stability problem. This paper proposes a new solution for the robust control problem of non-minimum phase systems by using the DOB. A non-casual, minimum phase transfer function is proposed to remove the internal stability problem in the design of DOB. The Poisson integral formula is used so that the bandwidth constraints of DOB, which occurs due to nonminimum phase characteristic, are analytically derived. The proposed method is applied to a general second order plant model with a RHP zero and system uncertainties. Simulation results are given to show the validity of proposed method.