Robust broadband control of acoustic noise in ducts: a passivity-based approach

An active feedback controller design methodology based on passivity-based robust control techniques is presented for broad-band noise control in an acoustic duct. The controller design methodology is demonstrated on an experimental one-dimensional (1-D) acoustic duct facility. The experimental results exhibit the effectiveness of the controller in suppressing 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 for a 1-D acoustic duct using analytical as well as system identification techniques. It is shown that the theoretically determined model agrees very well with the 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 only output feedback. Moreover, the controller is also low-order, robust, broadband, and has guaranteed stability.