Symbolic Kinematics of Special 3-RSR Parallel Mechanism with Zero Coupling Degree

A special 3-RSR antenna parallel mechanism (PM) with zero coupling degree is designed. The symbolic forward position solutions of the 3-RSR PM are obtained by using the kinematic modeling method based on topological characteristics. Meanwhile, the inverse position solutions of the PM are solved. The workspace of the PM is efficiently calculated based on the symbolic forward position solutions not on inverse position solutions that is traditionally used by most of researchers. The results lay a foundation for dimension synthesis and dynamic analysis of the 3-RSR PM.