Articles | Volume 9, issue 1
Research article
22 Jan 2018
Research article |  | 22 Jan 2018

Pa2 kinematic bond in translational parallel manipulators

Alfonso Hernández, Erik Macho, Mónica Urízar, Víctor Petuya, and Zhen Zhang

Abstract. The Pa2 pair is composed of two intertwined articulated parallelograms connecting in parallel two links of a kinematic chain. This pair has two translational degrees of freedom leading to a translational plane variable with the position. Currently, the Pa2 pair appears in conceptual designs presented in recent papers. However, its practical application is very limited. One of the reasons for this can be the high number of redundant constraints it has. But, it has to be considered that most of them can be eliminated by replacing wisely the revolute joints by spherical joints. On the other side, the structure of the Pa2 pair contributes to increase the global stiffness of the kinematic chain in which it is mounted. Also, its implementation is a promising alternative to the problematic passive prismatic joints. In this paper, the Pa2 pairs are used in the design of a 3 − P Pa2 parallel manipulator. The potentiality of this design is evaluated and proven after doing the following analyses: direct and inverse kinematics, singularity study, and workspace computation and assessment.

Short summary
In this paper the potentiality of using Pa2 joints for designing robots with parallel structure and translational motion is studied. As the equations governing its motion are simpler than those of other structures, the control system of the robot is more efficient and reliable. The structure proposed has high stiffness improving the accuracy of its movements.