Module combination based configuration synthesis and kinematic analysis of generalized spherical parallel mechanism for ankle rehabilitation.

• Based on the ankle bone structure, 6 high matching ankle motion fitting models are presented; • A generalized spherical parallel mechanisms (GSPM) which can fit the motion of these ankle models is proposed; • A module combination configuration synthesis method suitable for the GSPM is given; • A module combination kinematic analysis method applicable to the GSPM is summarized; • GSPMs with the similar kinematic characteristics to the 6 ankle models are established by the 2 methods above. In the previous rehabilitation robot research, the proposed ankle models for rehabilitation robot design have distinctions with the ankle bone structure. It leads to the unsatisfactory human-machine compatibility of the robots constructed based on the fitting onto the motion of these models. For this problem, 6 motion fitting models having higher similarities with ankle bone structure are proposed. For constructing a generalized spherical parallel mechanism (GSPM) with the same kinematic characteristics with these models, a module combination configuration synthesis method is presented. This method establishes the GSPM with partially decoupled characteristics by combining position and orientation modules. Firstly, this method constructs basic limbs/groups of 2 modules based on enumeration and screw theory. Secondly, a class of compact equivalent limbs and groups are constructed by equivalent replacement method based on basic limbs and groups. Thirdly, with the equivalent group being an example, the kinematics of 2 modules are analyzed based on the D-H method and their geometric characteristics, a module combination kinematic analysis method is summarized. Finally, 6 suitable GSPMs are established based on these methods. [ABSTRACT FROM AUTHOR]