Modelling and Simulation of a Self-Tuning Shock Absorber for Above-Knee Prosthesis

Y.C. Mao and C.P. Jiang (Taiwan)


Biomedical Engineering, Above-knee Prosthesis, Shock Absorber, Damping Coefficient.


The above-knee amputee body receives shock waves on each gait during walking and running. The shock force transfers through the prosthesis foot, limb structure and up to the trunk, producing a considerable damage to human body and joints. The shock absorber inside the prosthesis is an acceptable solution to absorb shock forces. A conventional shock absorber consists of a spring and a damper with constant coefficients, producing too rigid reactions when encountering impact forces, while extremely weak reactions for gentle loadings. This study proposes a novel shock absorber design for an above-knee prosthesis, which provides automatic smooth tuning of the damping coefficient. This design achieves the automatic tuning by a pressure-sensitive plunger valve system without any electronic devices. Theoretical modelling of the shock absorber is established in this study. Design parameters of the valve system under certain absorbing performance requirements are determined in this paper.

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