Design and analysis of a reconfigurable parallel mechanism with a variable center of rotation

To address the limitations of fixed topology and the absence of active regulation of the rotation center in conventional parallel mechanisms, we propose a novel 3SPS-U _r U _r reconfigurable parallel mechanism featuring a variable center of rotation. The degrees of freedom of the mechanism are analyzed using screw theory, and the inverse kinematic model along with the velocity Jacobian matrix are derived based on the closed-loop vector method. A global performance index is introduced to comprehensively evaluate the dexterity, payload capacity, and stiffness across the workspace. Structural parameters are optimized through a genetic algorithm, expanding the kinematic envelope of the mechanism. The workspace utilization in the two operational modes is enhanced by 145.49% and 22.57%, respectively.