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Modal control using real-time identification for time-varyingstructures

Published online by Cambridge University Press:  22 December 2010

Fengyan Deng ,
Didier Rémond  and
Luc Gaudiller
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Abstract

For a controlled structure, the changes of physical characteristics like naturalfrequencies, modal damping coefficients, and what’s more on mode shapes will destabilizethe controlled system. To keep the control performance and guarantee its robustness, a newmodal control method using real-time identification is proposed to overcome theinstability of controlled structure, especially induced by the inversion of mode shape. Inthis paper, a modal model of time-varying mechanical structure is supplied by anidentifier. The choice of the kind of control permits to use this time-varying model foroptimizing and self-adapting the controller. In order to supply the controller, a modalobserver is used and also updated. For illustrative purpose, this proposed methodology iscarried out on a simple but representative time-varying mechanical structure. On thisexample, an inertia modification leads not only to low modal frequency shifts but also toinversion of a mode shape. This mode shape inversion is shown to destabilize thecontrolled structure when the control system is not updated. The overall procedure will bedescribed through simulations and performed for different operating conditions, which willprove that mode shapes have to be precisely determined and updated in the controller andobserver to guarantee a robust modal control with high performances in spite of thechanges of structure.

Keywords

Self-adaptive controlreal-time identificationmodal controlmode shapestabilitystructurerobustness
Type
Research Article
Information
Mechanics & Industry , Volume 11 , Issue 6: VCB (Vibrations, Chocs et Bruits) , November 2010 , pp. 513 - 520
Copyright
© AFM, EDP Sciences 2010

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