Optimal selection of the supporting points of large component aligned and positioned by parallel manipulator

Abstract

Large components such as wing sections should be aligned and positioned in a desired position prior to the final manufacturing or assembly, so a digital alignment and position device based on six degree of freedom parallel manipulator with several prismatic-prismatic-prismatic-spherical branches was designed and fabricated to meet the needs. The digital alignment and position device is an alignment device based on the parallel manipulator, and it is also a positioning and holding fixture for large components manufacturing or assembly. In order to effectively and efficiently select the supporting points of large component where the digital alignment and position device branch is connected with, the performance of the parallel manipulator and the fixture should be comprehensively analyzed at the same time. The global performance indices such as the dexterity index, the bearing capacity index, and the stiffness index are calculated based on the mechanism Jacobean matrix of the parallel manipulator, and the positioning stability index is calculated based on the position Jacobean matrix of the fixture. The results show that the global performance indices are not related to the pose, but the positioning stability index is; in addition, all indices rely on the originally selected supporting points and provide the basis for the effective selection of the supporting points for large component aligned and positioned by the digital alignment and position device, which is based on parallel manipulator with prismaticprismatic-prismatic-spherical pairs.

An optimal singularity-free motion planning method for a 6-DOF parallel manipulator

“…Traditional manual docking mode is complex and expensive; therefore, more efficient approaches based on automated positioners or robotics have been studied in recent years (Xi et al, 2013;Qin et al, 2016;Drouot et al, 2018). Among them, parallel manipulators also show broad prospects in this fields owing to their ability of motion with multiple degrees of freedom and the advantages of strong carrying capacity, high stiffness and small motion errors (Mei and Maropoulos, 2014;Zhang et al, 2016). For example, a 6-SPS parallel kinematic robot was proved to have the potential to take place of the common 3-PPPS tripod in the aspect of flexible and precise assembly for the big and heavy parts (Löchte et al, 2011).…”

Sensitivity Analysis of Pose Error of a 3-PPPS Parallel Mechanism

“…Nowadays parallel mechanisms in aerospace for pose alignment are usually with several Prismatic-Prismatic-Prismatic-Spherical pairs (n-PPPS), and n represents the number of branch chain in one parallel mechanism [3]. Caro dealt with the non-singular assembly mode changing of a six-degree-freedom parallel manipulator, and the manipulator was composed of three identical limbs and one moving platform and each limb was composed of three prismatic joints of directions orthogonal to each other and one spherical joint [4].…”