Design and kinematic analysis of a novel planar parallel robot with pure translations

Abstract

The structural synthesis of a group of parallel mechanisms can be established by an exhaustive enumeration of all feasible kinematic chains based on the screw theory. However, reliable kinematic limbs can provide mobility constraints for some unqualified supporting legs to guarantee the degrees-of-freedom feasibility of the parallel robots. A systematic design approach is presented for a family of planar single-loop parallel mechanisms with the consideration of infeasible kinematic chains. Different from the other design approaches for single-loop linkages, the fixed and moving platforms are predefined in this research to distinguish different kinematic limbs. The special parallelogram linkage mechanism is incorporated due to its equivalent translation capacity. Three categories of singularity configurations are investigated based on the detailed kinematic models. The reachable workspace is obtained through the spatial search methodology. Several novel kinematic error model associated performance indices are proposed in this work and examined on a translational parallel manipulator. Experiments are carried out and compared to testify the effectiveness of the kinematic analysis and proposed position-based controller.