Reconfiguration Analysis of a Variable Degrees-of-freedom Multi-mode Parallel Manipulator

Reconfiguration analysis is essential for the design and control of multi-mode parallel manipulators (PMs). This paper deals with the reconfiguration analysis of a variable-DOF C/E= PM, which was first proposed by T.F. Parikian at the Sixth International Symposium on Advances in Robot Kinematics in 1996. This PM has a specified 2-DOF C= (cylindrical-joint-equivalent) operation mode and a specified 3-DOF E= (planar-joint-equivalent) operation mode. By representing the orientation of the moving platform using a Euler parameter quaternion (also Euler-Rodrigues quaternion), the motion characteristics in each operation mode are revealed with the aid of the kinematic interpretation of Euler parameters with different number of zero components. The reconfiguration analysis of this variable-DOF multi-mode PM shows that the PM has two extra operation modes in addition to its two expected operation modes. The transition configurations between each pair of operation modes of the PM are also identified.