An improved estimation method of secondary path uncertainties for feedback active noise control earphones

The fixed feedback control has been widely used for active noise-canceling earphones due to its simple structure and higher performance for low-frequency noise reduction. Although some disk-based models have been done to design robust controllers, they usually overestimate the uncertainty and thus limit noise reduction. In this article, we analyze the distribution of measured secondary paths and propose the tri-rectangle model to provide the uncertainty bound. The cascade biquad controllers are optimized by solving the multi-constrained optimization problem, with H2 performance criteria and H1 performance criteria and constraints of secondary path uncertainty and noise amplification. Simulation and experiment results show that the proposed tri-rectangle model provides a more accurate estimate of the uncertainty than disk-based models, and the designed controller achieves good noise attenuation with acceptable noise enhancement and strong stability.