Prosthesis is an artificial medical device used to replace a missing human body part. One challenge for such a device, which usually has a structure resembling the missing body part, is how to optimally satisfy the contradictory requirements of dynamic and static stability. In accord with ICM and stability of the natural human knee, we propose a new knee mechanism with an incongruent three-dimensional ICM pathway. This mechanism optimally solves the problem of dynamic and static stability with

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... he use of an elastic joint and deformation contact together with sliding and rolling technologies. This paper describes the schematic design, composition, and component functions of the proposed knee mechanism. From the design and composition of the mechanism, equations are derived for sliding and rolling conditions as prescription criteria, which provide a readily available theory for controlling these motions according to the component functions as well as the motion and definition of the ICM. Moreover, we analyze stability by considering dynamic and static stability under ideal conditions. The results show that the proposed knee mechanism will be promising for next-generation prostheses.