Robust adaptive feedback control of narrowband noise in a deformable exhaust duct.

Adaptive feedback control is widely used to suppress unknown narrowband noise, as it requires only a single error sensor for implementation. However, in practical engineering, the dynamic model employed to design the adaptive feedback controller often deviates from the actual secondary path, resulting in model uncertainty, such as when the secondary path is variable. Failure to adequately address such model uncertainty can degrade the noise suppression performance of the adaptive feedback control system and may even lead to instability. To overcome this challenge, this paper proposes a robust adaptive feedback control system that effectively suppresses unknown narrowband noise under model uncertainties. Based on the dual Youla parameterization and the regulation equation, a projection-type adaptive algorithm incorporating over-parameterization and a frequency-dependent weighting function is developed. Simulations and experiments on a deformable exhaust duct platform for narrowband noise suppression confirm the effectiveness of the proposed adaptive control system.