为研究零件对称结构对装配效率的影响，分析抓取和定向两种零件装配操作过程，逐一考虑零件上的多对称特征并分类为轮廓型对称特征和定向型对称特征。以三种不同装配要求下，六边形棱柱零件可能转动的最大角度为例，在总对称角概念基础上提出零件总修正角概念。结合现有试验数据，在满足“零件越对称，装配效率越高”和四个基本条件下，建立多对称特征下的零件“对称度-装配时间”预测模型。用五种模型预测四种不同多对称零件的装配效率，对比结果表明：零件“对称度-装配时间”预测模型与试验结果更接近，具有更好的区分度与可信性。

To study the influence of parts’ structure symmetry on assembly efficiency,grasping and orienting operations during parts’ assembling process are analyzed,and symmetry features within a part are separately considered and classified into contour and extra-orientation symmetry features. Taking the maximum possible rotating angle of a hexagonal prism part under three different assembling conditions as an example,the concept of total angle of correction (TAC) is proposed based on the existing concept of total angle of rotation (TAR). Using the existing experimental data,a part “symmetry-handling time” prediction model is proposed,which satisfies both the premise of “part’s assembly efficiency increases with its structure symmetry” and the four basic conditions. Four different parts assembly efficiencies are estimated using five different models,and comparing results show that the “symmetry-handling time” prediction model proposed fits the experimental data better and has better discriminability and credibility.