Affiliation:
1. School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
Abstract
A passive vibration absorber is proposed to mitigate tremors induced by Parkinson’s disease or essential tremor to replace costly and invasive alternatives. The proposed device is a wristband that, instead of classic spring–damper pairs, incorporates a shape memory alloy spring that acts as a nonlinear energy sink due to its hysteretic behavior. The mathematical models for the SMA spring and the patient’s forearm and hand are developed. To demonstrate the superiority of the SMA absorber, the proposed absorber’s performance is compared to a classic viscous absorber and also tested under unexpected harmonic forces. The simulations were performed in two parts. The first part used harmonic excitations as tremors to optimize SMA and viscous absorbers. The results indicated a 91% and 92% reduction in forearm and wrist tremors by the SMA absorber. The second part used real-world tremor data to compare the absorbers. Simulation results indicated that the viscous absorber reduces tremor power to an average of 55% in the 3–25 Hz range. In comparison, the SMA absorber has an average 92% tremor PSD reduction in the said range, which is significantly higher than the viscous absorber.