基于组合基元法的非理想模型装配偏差预测算法研究

Assembly deviation prediction algorithm of non-ideal model based on combined primitive method

基于模型定义(model-based definition,MBD)体系的装配偏差算法适用于赛博空间中理想数模的装配场景,但不适用于物理空间中非理想状态的装配场景,导致现场产生大量修配工作。针对这一问题,文章模拟真实的装配场景,基于零件的非理想状态,并将配合特征之间的拓扑关系考虑在内,对装配偏差的传递与累积过程展开研究,给出一种装配偏差预测算法。首先,针对孔轴配合与槽轴配合,将装配约束转化为定位点约束,依据最大实体原则,构造柱面点云的最小包围圆,确定接触状态,给出串行装配偏差算法,并将以上两种配合定义为两种基元,对应的装配偏差算法定义为两种独立基元算法。其次,基于平面贴合、孔轴配合与槽轴配合给出并行装配偏差算法,并将其定义为组合基元算法。最后,基于非理想模拟数据进行实例验证,达到了准确预测装配偏差的目标,为后续在赛博空间基于实测数据的装配偏差计算提供理论依据,以促进高精度装配。

The assembly deviation algorithm based on model-based definition(MBD) system is suitable for the assembly scenes of ideal digital models in cyberspace,but not for the assembly scenes of physical space under non-ideal conditions,resulting in a lot of repairs.Aiming at this problem,simulating real assembly scenes,the transmission and accumulation process of assembly deviation is studied based on the non-ideal state of parts,an assembly deviation prediction algorithm is proposed.Also,this algorithm takes into account the topological relationship between mating features.Firstly,for the hole-axis fit and slot-axis fit,the assembly constraints can be transformed into point location constraints.Based on the maximum material principle,the minimum bounding circle of the cylindrical point cloud is constructed to determine the contact state,and a serial assembly deviation algorithm is provided.Moreover,the above two kinds of matches are defined as two basic elements,the corresponding assembly deviation algorithms are defined as two independent primitive algorithms.Secondly,the parallel assembly deviation algorithm is given based on planar match,hole-shaft match and slot-shaft match.And it is defined as a combined primitive algorithm.Finally,an example is verified based on non-ideal simulated data to accurately predict assembly deviation,which provides a theoretical basis for subsequent assembly deviation calculation based on measured data in cyberspace to promote high-precision assembly.