Tremor Reduction at the Palm of a Parkinson’s Patient Using Dynamic Vibration Absorber

Abstract

Parkinson’s patients suffer from severe tremor due to an abnormality in their central oscillator. Medications used to decrease involuntary antagonistic muscles contraction can threaten their life. However, mechanical vibration absorbers can be used as an alternative treatment. The objective of this study is to provide a dynamic modeling of the human hand that describes the biodynamic response of Parkinson’s patients and to design an effective tuned vibration absorber able to suppress their pathological tremor. The hand is modeled as a three degrees-of-freedom (DOF) system describing the flexion motion at the proximal joints on the horizontal plane. Resting tremor is modeled as dual harmonic excitation due to shoulder and elbow muscle activation operating at resonance frequencies. The performance of the single dynamic vibration absorber (DVA) is studied when attached to the forearm and compared with the dual DVA tuned at both excitation frequencies. Equations of motion are derived and solved using the complex transfer function of the non-Lagrangian system. The absorber’s systems are designed as a stainless steel alloy cantilevered beam with an attached copper mass. The dual DVA was the most efficient absorber which reduces 98.3%–99.5%, 97.0%–97.3% and 97.4%–97.5% of the Parkinson’s tremor amplitude at the shoulder, elbow and wrist joint.

Parametric study of an enhanced passive absorber used for tremor suppression

“…For low damping coefficients, the reduction is higher. This was proved by Gebai et al, where the effect of the variation of damping coefficient of a conventional absorber on the percentage of reduction in the flexion angular displacement and similar results were studied. The study shows that as the damping coefficient decreases, the percentage of reduction increases but with a decrease in the yielding and fatigue safety factors of the absorber's beam.…”

“…The same strategy used by, based on the Dunkerley's semi‐empirical formulation, is followed to size the absorber. The effect of the absorber's mass (total mass and mass distribution) and damping coefficient on the reduction in the flexion angular motion at the upper limb's joint is still under study.…”

“…The dynamic equations of motion of the upper limb controlled by the SEVD are derived using the non‐Lagrangian formulation as detailed in . The SEVD is attached to cause the reduction in the flexion motion amplitude at different joints.…”

“…The series elastic viscous damper (SEVD) absorber proved its effectiveness over the conventional SDOF absorber (spring and damper connected in parallel) having the same total mass. Gebai et al studied the effect of the damping ratio of a conventional parallel dual absorber on the reduction in the percentage of tremor amplitude and the safety factor of the absorber. These absorbers were attached to a three DOF upper limb system designed previously .…”

Experimental Testing of Passive Linear TMD for Postural Tremor Attenuation

“…In the current work, an experiment is conducted to study the ability of passive TMD in reducing the amplitude of complex types of signals, the PT signal, which can be modeled as a second-order non-linear Stochastic oscillator [16], Gaussian noise signal [17], etc. The passive TMD having mass, stiffness, and damper as the effective elements, is fabricated in the form of a Cantilever-type TMD, as the design suggested by Gebai et al [18]. However, in the current design, the beam has a circular cross-section as shown in Figure 3.…”