具有驱动容错性的冗余并联机构构型综合

Type Synthesis of Redundant Parallel Mechanism with Actuation Fault Tolerance

目前并联机构大多采用容错控制策略实现驱动故障容错,而从并联机构结构设计角度研究较少。本文基于雅可比矩阵,提出一种评价并联机构分支驱动力失效的可操作性失效度指标,并以冗余并联机构为研究对象,给出机构具有驱动力失效容错性的驱动“同一性”条件。基于螺旋理论,提出一种具有驱动容错性的冗余并联机构构型综合方法,综合出一类具有驱动容错性的三转动冗余并联机构新构型。本文为解决冗余并联机构驱动力失效问题提供了新的思路,丰富了并联机构的构型,为具有驱动容错性的冗余并联机构的应用发展提供了理论基础。

The control methods are mostly used for the fault tolerance of parallel mechanism at present.However,there are few studies on structure design of parallel mechanism with actuation fault tolerance.To quantitatively analyze the influence of driving force invalidity on the operability performance of mechanism,an operability invalidity index was proposed for evaluating the driving force invalidity of the branches of the parallel mechanism based on the Jacobian matrix.The driving identity condition of the redundant parallel mechanism stated as“the driving force screw of the redundant parallel mechanism was expressed in the same form in a fixed coordinate system,and the linear independent number of the driving space was equal to the degree of freedom.If any driving force screw(driving force invalidity fault)was removed,the driving space would not degrade”,that satisfied the driving force invalidity tolerance was given.Based on the screw theory and guided by the driving identity condition,which promised that the driving force screws can be mutually substituted,a type synthesis method of redundant parallel mechanism was proposed,and a 3R DOF type of redundant parallel mechanisms with actuation fault tolerance was synthesized.The actuation fault tolerance of the(4RRR)_(Ⅰ)redundant parallel mechanism synthesized was evaluated by using the proposed operability invalidity index,which verified that the synthesized mechanism had the drive force invalidity tolerance.The research result can provide a way to solve the driving force invalidity of parallel mechanism,and can enrich the types of parallel mechanism,which provided a theoretical basis for the application and development of redundant parallel mechanism with actuation fault tolerance.