Design and kinematic analysis of a spherical parallel manipulator using concurrent planar parallelogram linkages

This paper presents the design of a novel spherical parallel manipulator. The spherical parallel manipulator consists of three identical limbs and each of them is formed by a planar parallelogram linkage, a universal joint, and a revolute one, successively. Its mobility is analyzed using the reciprocal screws. After that, the kinematics is analyzed in detail, including inverse kinematic modeling, which is validated by a numerical example, inverse Jacobian analysis, singularity analysis, and manipulability analysis, which shows a relatively good performance of force transmission. Then based on the analysis, one prototype is fabricated to validate the effectiveness and feasibility of the design. In the end, some conclusions are drawn and future works are discussed.