Passive vibration absorber for tremor in hand of parkinsonian patients: Tuned vibration absorber for rest tremor

Parkinson's disease is characterized by involuntary movement of body parts resulting from antagonistic muscle contractions. In this paper, an effective passive vibration absorber is modeled to control the involuntary pathological rest tremor in the right hand of Parkinson's disease patient. The three-degree-of-freedom dynamic hand model capable to describe the flexion-extension planar motion at shoulder, elbow, and wrist joints in horizontal plane is designed. The passive tuned vibration absorber is modeled to suppress flexion motion of shoulder, elbow and wrist joints. Active inputs producing motion are considered at shoulder and elbow joints, and driven at resonance frequencies. The equations of motion for the dynamically coupled modeled hand system are derived. The responses are represented in time and frequency domains using the complex transfer function method. Optimum position of the absorber on the forearm is determined in terms of its effectiveness in reducing tremor's amplitude.