Preview-Based stable-inversion for output tracking of linear systems

Abstract

Stable Inversion techniques can be used to aciiieve liigh-accuracy output tracldng. However, for nonminimum ptiase systems, tJie inverse is noncausal-hence the inverse has to be precomputed using a prespecified desired-output trajectory. This requirement for pre specification of the desired output restricts the use of inversion-based approaches to trajectory planning problems (for nonminimum phase systems). In the present article, it is shown that preview information of the desired output can be used to achieve online inversion-based output-tracking of linear systems. The amount of preview-time needed is quantified in terms of the tracking error and the internal dynamics of the system (zeros of the system). The methodology is applied to the online output tracking of a flexible structure and experimental results are presented. © 1999 ASME.