以 DFA分级装配模型为研究重点 ,按装配零件的外形将其进行分类。对每个零件建立了局部坐标系 ,计算出不同零件之间的相对位置姿态。分析了零件重要的邻接关系 ,特别是面面配合和轴孔配合。基于邻接的几何特征 ,得到了以位置姿态矩阵为未知变量的方程组。采用牛顿—拉斐森迭代方法和最小二乘方法求解此非线性方程组 DFA hierarchical assembly model for the study focus, according to the shape of the assembly parts to be classified. For each part of the establishment of a local coordinate system to calculate the relative position and orientation between different parts. The important adjacencies of the parts were analyzed, especially the face-to-face fit and shaft bore fit. Based on the geometric features of the adjacency, the system of equations with position and orientation matrices as unknown variables is obtained. This nonlinear system of equations is solved using the Newton-Raphson iterative method and the least square method