Design and analysis of a novel reconfigurable parallel mechanism with three motion modes

This study proposes a gear-driven switching device for the 2RPS-UPU parallel mechanism, utilizing the correlation between constrained screws generated by branch chain to achieve mechanism reconfiguration, thereby obtaining a reconfigurable parallel mechanism capable of three motion modes: 2R1T, 2R1T, and 2R2T. The study meticulously delineates the conditions required for reconfiguration and the specific process involved. Evolving from three initial motion mode configurations, nine novel mechanism configurations have been successfully derived. Employing screw theory, the degrees of freedom for these initial motion mode configurations are rigorously analyzed and validated. Furthermore, inverse kinematic equations and Jacobian matrices for the three modes are constructed, enabling an in-depth investigation of key performance indicators such as motion capability, workspace, singularity, dexterity, and stiffness. A single-variable approach is adopted to analyze the influence of multiple structural parameters on different performance indicators. The results demonstrate that the proposed reconfigurable parallel mechanism possesses robust performance, allowing for active switching between various motion modes without the need for reassembly. Finally, a potential practical application is presented, laying the foundational principles for the subsequent prototype design and manufacturing.