Significant structural vibration is an undesirable characteristic in helicopter flight that leads to structural fatigue, poor ride quality for passengers and high acoustic signature. Previous Individual Blade Control (IBC) techniques to reduce these effects have been hindered by electromechanical limitations of piezoelectric actuators. The Smart Spring is an active tunable vibration absorber using IBC approach to adaptively alter the "structural impedance" at the blade root. In this paper, a mathematical model was developed to predict the response under harmonic excitations. An adaptive notch algorithm was designed and implemented on a TMS320c40 DSP platform. Reference signal synthesis techniques were used to automatically track the shifts in the fundamental vibratory frequency due to variations in flight conditions. Closed-loop tests performed on the proof-of-concept hardware achieved significant vibration suppression at harmonic peaks as well as the broadband reduction in vibration. The investigation verified the capability of the Smart Spring to suppress multiple harmonic components in blade vibration through active impedance control.

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Keywords Active tunable vibration absorber, Helicopter vibration control, Smart structure
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Journal Chinese Journal of Aeronautics
Chen, Y. (Yong), Zimcik, D.G. (David G.), Wickramasinghe, V.K. (Viresh K.), & Nitzsche, F. (2003). Research of an active tunable vibration absorber for helicopter vibration control. Chinese Journal of Aeronautics, 16(4), 203–211. doi:10.1016/S1000-9361(11)60185-4