CoPaRo: A Compact, Backdrivable 6-DOF Hybrid Parallel Robot with Serial-Like Form Factor and Large Workspace
Samuel Verret, Clement Gosselin
Abstract
A novel, compact, backdrivable 6-degree-of-freedom (DOF) hybrid parallel robot with a large axisymmetric workspace is proposed, referred to as CoPaRo, short for Compact Parallel Robot. The architecture achieves a high workspace-to-footprint ratio comparable to that of serial robots. The proposed robot is well suited for physical human-robot interaction (pHRI) due to its low inertia, backdrivability, and large workspace. A complete kinematic analysis is provided, including forward and inverse kinematics and velocity equations. All singularity conditions of the proposed architecture are identified, and the complete usable workspace is presented, accounting for singularities, mechanical interferences, and numerical stability. A CAD model and computer animations of the robot are provided to illustrate its motion, highlighting both the compact footprint and the large workspace. The actuators are positioned close to the base and transmit motion to distal joints via pulleys to reduce the robot's inertia. Direct-drive or quasi-direct-drive actuators can be used to enable backdrivability.