Time-varying noise control in motorcycle helmets

The active noise control problem in motorcycle helmets is studied, which has an intrinsic time-varying behavior. The time-varying approach is designed to have an attenuation level that increases with the speed between the helmet and the air using a linear parameter-varying (LPV) controller. To achieve a reasonable noise attenuation, the noise source and its dynamic characteristics are computed. Three different experiments were performed, an experiment on the noise dynamics, identification tests and an experiment on controller implementation. The identification tests were carried out using six sinusoidal sweeps as system excitation signals. Between each sweep, the system was perturbed to include various practical situations. Regardless of the attenuation results, the alternative of having a controller that changes its performance as a function of the helmet speed is attractive.