A hybrid 6-DOF mechanism with closed-form position solutions employing two 3-DOF modules with decoupled output motions

A hybrid 6-DOF (degrees of freedom) mechanism which has closed-form forward and inverse position solutions is proposed. It consists of two different modules, a planar 3-DOF parallel module and a spatial 1T2R (1-DOF translational motion and 2-DOF rotational motions) parallel mechanism. Both modules have forward and inverse closed-form position solutions and further their output motion spaces are completely decoupled each other. First, the planar 3-DOF module employing parallelogram joints, which could minimize joint friction significantly, is described. Then its closed-form solutions are derived and its kinematic analysis is performed. After brief description on the spatial 1T2R 3-DOF parallel mechanism, the forward and inverse closed-form solutions and the kinematic model for the hybrid 6-dof mechanism composed of those two modules are discussed. Then, its kinematic isotropic characteristic is investigated to show its high potential for practical applications. Finally, the motion capability of the planar 3-DOF module and the 6-DOF hybrid mechanism are verified through their motion simulators developed.