一种四自由度空间并联机构的奇异容错纠错策略与方法研究

Study on Fault Tolerance and Fault Rectification Strategy and Approach for Singularities of a 4-DOF Spatial Parallel Mechanism

以Gosselin的奇异分类为基础,将第二类奇异位形对并联机构的不利影响看成是一种机械系统故障,提出了结合冗余驱动的并联机构奇异容错纠错策略框架。阐述了该容错纠错策略框架的基本思想和实现步骤,用线性方程组解的情况和矩阵条件数解释了该奇异位形"故障"发生和被克服的实质,以此为基础定义了描述奇异被消除程度的奇异容错度指标,基于该指标提出了容错结构优化算法,用来确定使并联机构具有最佳奇异容错能力的冗余驱动的结构参数。分析得到了2RPS&2TPS型并联机构的一个典型的第二类奇异位形,比较了三种奇异容错策略克服这一奇异位形效果的优劣,对这三种容错纠错策略进行了仿真研究,结果表明,提出的以奇异容错度为依据的容错纠错策略能有效克服奇异位形的不良影响。

Based on singularity classification approach of Gosselin,singularities of type Ⅱ were treated as a kind of mechanical system faults,a fault-tolerance and fault-rectification strategy framework for eliminating singularities was presented based on actuation redundancy herein.Basic idea and implementation process of this framework were expatiated,the essence of singularity occurring and singularity being removed were interpreted by solutions of linear equations and matrix condition number.Degree of singularity fault-tolerance was defined as an index for describing the performance of singularities being eliminated.Based on this index,an optimization algorithm was proposed to determine optimal structural parameters for the redundant actuation,which enabled parallel manipulators to possess maximum singularity fault-tolerance ability.A typical singularity loci for 2RPS2TPS parallel mechanism was obtained,three fault-tolerance and fault-rectification strategies were presented and compared in details.Simulation researches for above three fault-tolerance and fault-rectification strategies were conducted.Simulation results show that the fault-tolerance and fault-rectification strategy based on degree of singularity fault-tolerance can eliminate side effect of singularities in parallel mechanisms effectively.