239 / 2021-04-14 12:14:27

Reduction of a hand tremor using an active mass damper and an adaptive filter-based controller

Tremor, Surgery, Active mass damper, Frequency analysis, Adaptive filter

Physiological tremor is an involuntary vibrating motion observed in human body. The tremor can be observed in most human arms under excessive stress or chills even at physically well condition. Therefore, the tremor may cause anyone a bad effect on precise operation, e.g., welding and surgery. 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. Tremors were measured while the subjects kept the tip of the needle in place. 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.