Kinematics Analysis and Performance Optimization of Multimode Reconfigurable Parallel Ankle‐Rehabilitation Mechanism

ABSTRACT This study proposes a multimode reconfigurable parallel ankle‐rehabilitation mechanism to solve the problem that the current ankle‐rehabilitation mechanism rehabilitation mode is single and difficult to meet the diverse needs of patients at different stages of recovery. The mechanism achieves variable degrees of freedom (DOFs) by adjusting the positional relationship among the drive joint axes to accommodate different rehabilitation motion modes. Screw theory was employed to analyze the mechanism's motion characteristics across various configurations. A closed‐loop vector method was adopted to establish the inverse kinematics model, and the correctness of the positional inverse solution was verified. Taking the one translational and two rotational DOFs and three rotational DOFs modes as examples, the workspace and motion/force transmission performance of the mechanism in these two modes were analyzed. The structural dimensional parameters of the mechanism were optimized using the spatial model method, yielding a performance distribution map. On the basis of this analysis, the optimal dimensional region was determined, leading to enhanced kinematic performance. The results demonstrate that the reconfigurable parallel mechanism meets the motion requirements of ankle rehabilitation and exhibits excellent kinematic performance within its rehabilitation range.