Performance analysis of 3-(HS)S/S parallel ankle rehabilitation robot

A 3-(HS)S/S parallel ankle rehabilitation robot designed to improve ankle rehabilitation is proposed, based on structural characteristics, injury mechanism, and movement pattern of the human ankle. The degrees of freedom analysis based on screw theory was executed and the inverse kinematic solution was obtained, resulting in resolution of the workspace. The effects of structural parameters, including the platform radius (r), the length of the middle pole constraint (h), the angle between the support rod and the fixed platform (d), on the workspace were investigated. The results revealed that the velocity and acceleration of the moving platform is inversely proportional to d, while the workspace size is proportional to d and inversely proportional to the length of the central rod and the radius of the moving platform. Additionally, the displacement, velocity, acceleration and the workspace can be adjusted accordingly by tuning d, the length of the central rod, and the radius of the moving platform, to optimize ankle rehabilitation.