Stable Dynamic Inversion of Nonminimum-phase Scalar Linear Systems

Authors:	Piazzi Aurelio, University of Parma, Italy Pallastrelli Daniele, SELTA, Italy
Topic:	2.2 Linear Control Systems
Session:	Linear Systems III
Keywords:	Feedforward control, inversion, non-minimum phase systems, linearsystems, transfer functions.

Abstract

The paper presents a transfer function approach to the stabledynamic inversion of nonminimum-phase scalar linear systems. Thetechnique is based on the study of the structure of the causalunstable input obtained with the standard inversion technique. Itis shown that the unbounded term of this input can be decomposedas the sum of a linear combination of unstable zero modes forwhich new formulae are provided. Then, a closed-form expression ofthe bounded noncausal solution of the input-output inversionproblem is proposed. An automatic inversion scheme built byexploiting the new inversion formula is also presented.