LAUSR

Tremor is a semi-rhythmic oscillatory movement of a body part caused by alternating simultaneous contractions of an antagonistic muscle group. Medical and surgical treatments used to reduce the symptoms of involuntary tremor causes negative side effects. This study examines the ability of passive vibration absorbers in reducing the amplitude of postural tremor (PT) type of involuntary tremors. An inertial measurement unit (IMU) is used to record PT signals at the forearm and hand of a patient. IMU signal is used as the active excitation input of an upper limb system modeled to represent the flexion-extension vibrational motion at the joints. Equations of motion are solved numerically to obtain a simulated response that fits the measured tremor signal. passive tuned mass damper (TMD) is modeled as a thin lightweight cantilever beam with a screw located at the position reflecting its operating frequency. Natural frequency of the TMD is derived for different screw positions and validated numerically and experimentally. Modal damping ratio of the TMD for each screw position is also estimated. Optimization of screw position and damping coefficient of the TMD depends on the minimization of the angular displacement amplitude at the wrist joint. A lightweight optimized three-TMD system of 28.64 g total effective mass, simulated using its estimated modal damping ratios, shows its effectiveness compared to the literature, in reducing 65-83% of the amplitudes at the joints. An experimental arm is prepared for further experimental validation before the design of a wearable anti-vibration bracelet.