Singularity Elimination of 3-RPR Planar Parallel Mechanisms Via Topological Reconfiguration

A new approach is presented for singularity elimination of 3-RPR (R and P refer to revolute and prismatic joints, respectively; the underlined type of joints is the active one) planar parallel mechanisms through topological reconfiguration. First, the parallel mechanism’s mobility, kinematics and Jacobian matrices are formulated explicitly. Then, the Jacobian-rank deficiency conditions are revealed, and the first and second kinds of singularities for the general 3-RPR planar parallel mechanism are depicted. Subsequently, the analysis of singularities is conducted to reveal that the singularity loci of planar parallel mechanisms can be fully eliminated through topological reconfiguration. This method is implemented on a 3-RPR planar parallel mechanism that can be reconfigured into a 3-RRR one by means of a novel metamorphic joint. Finally, a numerical case is executed, and the results show that the singularity loci of this parallel mechanism thoroughly vanish through topology switching, thereby demonstrating the effectiveness of the proposed methodology.