中文摘要：

为解决计算机辅助工艺设计中定位基准选择问题，提出了定位基准推理过程的形式化方法，分析工件定位中各种知识的约束关系。首次应用多色集合理论的个人颜色、统一颜色和递阶结构树，建立了工件定位基准递阶结构信息模型。以三平面定位方式为例，确定第一、第二和第三定位基准围道矩阵。建立了启发式定位基准选择顺序，按照工件定位基准围道矩阵确定的标准，以箱体类零件为例，验证了所提方法的有效性。

英文摘要：

A formalized method of position planning was proposed to solve the location datum selection of Computer Aided Process Planning （CAPP）. Restrictions of knowledge for the position planning were analyzed and formalized by employing the relation matrix of unified colors and individual colors. The unified color sets, individual color sets and hierarchy structural tree were applied to construct a position planning model for mechanical part. Taking the position style of three-plane as an example, location datum contour matrix was established. A heuristic location datum selection sequence was put forward. According to the standard of the location datum contour matrix, an application case of box part was provided to verify the proposed method.