R-CUBE, a decoupled parallel manipulator only with revolute joints

A new 3-DOF translational parallel manipulator, named R-CUBE, is presented in this paper. This manipulator has decoupled motion in x, y, and z axes, and employs only revolute joints. The structure and kinematics of the manipulator are studied, which shows there exist rotational redundant constraints to the moving platform. A modified structure is also introduced to avoid the redundant constraints. The mechanism singularity is examined.