Active control of structures using time delayed positive feedback proportional control designs

Abstract

This paper explores a new methodology for the active control of structures through the use of time delayed, positive feedback proportional control. The idea is to utilize intentional time delays, which may not necessarily be small when compared with the natural periods of vibration of a structure. Such time delayed systems are infinite dimensional. Analytical and computational results related to both system and non-system poles are herein provided for the first time. Results related to the stability of the presented control methodology are given. The efficacy of the control design is illustrated by applying it to a structure modelled as a single-degree-of-freedom system subjected to strong earthquake ground shaking. It is shown that while displaying good stability characteristics, the performance of such time delayed positive feedback proportional control can be even superior—in terms of both, reduced structural response, and reduced control effort—to standard proportional negative feedback control designs with no time delay. Copyright © 2005 John Wiley & Sons, Ltd.