Development of an active muffler for medium-duty diesel vehicles considering thermal influence and control trackability

A practical exhaust muffler using an active noise control (ANC) system was studied for reducing harmonic noise with a fundamental frequency which is the main component of exhaust noise generated by a medium size diesel engine truck. A special layout of the muffler structure, which can attenuate the thermal affect to an ANC speaker by exhaust gas, was designed, and a time based synchronized filtered-X algorithm with a modified variable step size method is proposed as the control strategy applicable to a time-varying environment. The effectiveness of this system is verified after applying the ANC system to exhaust noise control of the truck for operation during acceleration.