Multichannel Adaptive Filter with Assured Stability and Its Applications to Active Noise Control

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In multichannel active noise control with a multiple number of primary noise sources, secondary control sources, reference microphones and error microphones, a class of new stability-guaranteed adaptive algorithms have been investigated to update the feedforward controllers for generating artificial control sounds to cancel the noises at the error microphones. The results obtained by this project can be summarized as follows : (1) The obtained robust adaptive algorithm is stability-guaranteed for any changes of the primary channels by assuming the secondary channels are known a priori and an upper bound of additive uncertainties is given. (2) Two identification-based adaptive schemes have been proposed to compensate for uncertain changes of the secondary path matrices as well as the primary ones. In the first scheme the secondary control sounds can be calculated in an on line way by taking the FFT and inverse FFT corresponding to the identified two equivalent path matrices. In the seco … More nd scheme, we update the error system in adequate timings to adjust the adaptive feedforward controller. (3) A new plug-iii type of adaptive algorithms with assured stability have also been investigated when the primary source noises are periodic. This approach requires no reference microphones and then will provide an attractive scheme for industrial applications. (4) A new adaptive filtering algorithm is derived to improve the tracking performance for time-varying unknown parameters. All of the conventional adaptive approach adopt LMS algorithm assuming that unknown parameters are constant. However, the proposed approach involves an internal model describing the dynamic behavior of time varying parameters and can track rapid changes of the unknown parameters. (5) Finally, we have examined the effectiveness of the proposed adaptive schemes in two experimental studies, for instance, adaptive active noise canceling in an air duct and adaptive active noise control for the moving points. The results are compared with other conventional approaches. The proposed adaptive feedforward control schemes can also be extended to applications of the active vibration suppression control of structures excited by seismic accelerations. Less