基于非瞬时支链位形设计的并联机构内部奇异消除方法

Inside Singularity Elimination Method for Parallel Mechanisms Based on Non-instantaneous Branch Link Configuration Design

引入新支链的冗余驱动方法是目前减少或消除并联机构奇异的有效方法,如何确定所引入支链的结构形式、布置方式和最少支链个数是该冗余驱动方法的核心问题,然而关于这些问题至今尚没有系统的理论和方法。依据螺旋理论系统分析并联机构的约束奇异、驱动奇异和支链奇异三种奇异位形,强调位于工作空间内部的约束奇异和驱动奇异位形是对机构性能影响最为严重的位形,提出一种基于非瞬时支链位形设计的并联机构内部奇异消除方法,以3-RPR型、3-RRR型、4-RPTR型、3-RRRT型和3-RPS型等五种典型的并联机构为例,系统阐述该方法的设计过程。结果表明除了动平台和基平面重合的位形以外,该方法能够消除并联机构的其所有内部奇异位形。该成果为解决冗余驱动方法的关键理论问题提供了参考。

The redundant actuation method based on adding new branch linkages to parallel mechanism is now a very effective method which is used to reduce or eliminate singularities of parallel mechanism.How to determine the architecture,the layout and the least number of the branch links added is a key problem of the redundant actuation,but until now,there aren＇t any systematic theory and means for them.Constraint singularity configuration,drive singularity configuration and branch singularity configuration are systematically discussed based on the screw theory,and it is emphasized that the constraint singularity configurations and drive singularity configurations exist within the workspace create the most severe effect on performance of parallel mechanisms.An inside singularity elimination method for parallel mechanisms based on non-instantaneous branch link configuration design is presented.The 3-RPR,3-RRR,4-RPTR,3-RRRT and 3-RPS parallel mechanisms are taken as examples for systematically expatiating design course of the inside singularity elimination method.The results show that except for the configuration under which motion platform superposes base plane,the other inside singularity configurations can be eliminated entirely.The research achievements provide a reference for the solution to the key problems on redundant actuation method.