Two approaches based on pole sensitivity and stability radius measures for finite precision digital controller realizations

Abstract

This paper compares the two approaches based on pole sensitivity and the complex stability radius measures, respectively, for optimizing the closed-loop stability robustness of digital controllers with respect to finite word length (FWL) errors in fixed-point implementation. Design details and related optimization procedures are derived for the two methods. The two measures, although derived from different motivations, can both be regarded as lower-bound measures of a true but computationally intractable FWL stability measure in some senses. An example is used to verify the theoretical analysis and to illustrate the two designs for determining optimal FWL controller realizations.