Control of tremor by frequency-tracking notch filter

Abstract

In this study, we developed an active device used to suppress the essential tremor in human limb. An active-type mass damper was introduced to mitigate tremor in human hand, where the mass was actively driven using a voice coil motor. In addition, a single-frequency adaptive notch filter-based controller was introduced to drive the damper mass. Experiments were carried out where the simulated microscopic surgery was imposed on subjects, whose forefinger was equipped with the active mass damper. The acceleration served as an error signal by which the adaptive filter coefficients were updated and the error function was minimized. Subjects were asked to grip a needle having a relatively small diameter using tweezers; they were also asked to insert it in a needle with a larger diameter. Furthermore, another notch filter-based dominant frequency estimation system was developed for the controller. Although the challenges still need to be solved, the active damper to be used with the adaptive-type controller was shown to be effective for attenuating the vibration.