为解决已有地铁洞门钢环检测及数据处理方法略显复杂且不具备抗差性的问题，在对洞门钢环精密检测方法研究的基础上，提出基于RANSAC的地铁洞门钢环空间形态拟合参数的一步解法，实现通过洞门圆心、半径、平整度、垂直度和圆度等洞门参数对地铁洞门钢环的空间形态分析和质量评价；以C#编程语言和SQL Server数据库为工具将该算法程序化，采用Leica TM30测量机器人对南京轨道交通5号线五台山站洞门钢环进行检测，并对实测数据进行计算与分析。结果表明： 该方法能够抵抗异常值对洞门空间形态拟合结果的扰动，是一种更为有效、实用的地铁洞门钢环检测与数据处理方法。

The existing metro portal steel ring detection and data processing method is slightly complicated and have no ability to resist gross errors. As a result, based on the study of precision detection method of the portal steel ring, a RANSACbased onestep solution for the spatial shape fitting parameters of the metro portal steel ring is proposed. The spatial shape analysis and quality evaluation of the metro portal steel ring can be realized through the portal center, radius, flatness, verticality and roundness. The proposed algorithm is programmed with the C# programming language and the SQL Server database as tools; the Leica TM30 measuring robot is used to detect the steel ring of the portal door of Wutaishan Station on Nanjing Rail Transit Line No.5; and the measured data are calculated and analyzed. The results show that the proposed method can resist the disturbance of abnormal value to the portal steel ring spatial shape fitting results, which indicates that it is a more effective and practical method for detection and data processing of the metro portal steel ring.