Robust Broadband Control of Acoustic Noise – A Passivity-Based Approach


Prof. Atul Kelkar
Mechanical Engineering
Iowa State University
Ames, Iowa 50014


An active feedback controller design methodology based on passivity-based robust control techniques is presented for a broad-band control of acoustic enclosures. Acoustic enclosure systems being inherently non-passive the passification techniques are used to render such systems passive. The concept of robust passification is used to recover the robustness properties of passivity-based control design. The controller design methodology is demonstrated on an experimental 1-D, 2-D, and 3-D acoustic enclosures. For the case of 3-D enclosure, acoustic-structure interaction dynamics is also considered. The specific configuration of interest is the one in which an acoustic disturbance is created by one of the vibrating boundaries of the enclosure such as in the case of aircraft cabin noise. The experimental results exhibit the effectiveness of the controller in suppressing the acoustic noise levels over a broad frequency range without destabilizing high frequency dynamics of the system. The controller design is shown to be robust to unmodelled dynamics and parametric uncertainties. A finite dimensional mathematical model is derived using analytical as well as system identification techniques. It is shown that the theoretically determined model agrees very well with experimentally identified system model. The control design methodology exploits inherent robustness of passivity-based controllers and selective mode attenuation capability of resonant mode controllers. The controller is easy to implement as it uses output feedback. Moreover, controller is also low-order, robust, broadband, and has guaranteed stability. An audio-visual demonstration will also be given to assess the effectiveness of the control system.
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