Kinematic analysis on spatial rotation 4-SPS-1-S parallel manipulator with a passive constraining spherical joint

This paper proposes a new parallel manipulator with three purely rotational degrees of freedom, which consists of four SPS active legs and one passive constraining leg. The passive leg is introduced into this new parallel manipulator in to increase load capacity, stiffness and reliability of the structure, and to eliminate any redundant motion. Kinematic analysis of the manipulator is presented, including inverse position analysis and velocity mapping equations. Kinematic simulation on the mechanism is conducted using MATLAB software. Kinematic control strategies are proposed based on simulation results. The parallel manipulator can be applied to precise positioning tasks under heavy-loading conditions, and is of great importance in engineering application.