A Double Input - Quadruple Output Adaptive Controller for the Active Headrest System

A system known as active headrest, generating the so-called zones of quiet at the ears of a person sitting in a chair is considered. It is shown that zones of highest noise reduction generated by a classical double input - double output control system do not reach the ears. To extend the zones four secondary sources, one located over another for each channel, are applied. The error microphones, one for each channel, are mounted between respective sources. Ali the components are arranged not to annoy the user, what impacts system performance. Internal model control with Filtered-x LMS algorithm is employed. Obtained results are presented graphically in the form of surfacial distribution of reduction areas. They confirm the expectations that the zones of high reduction significantly extend comparing to the double input - double output control system and really reach the ears, even in case of practical head movements.