Abstract: A simple formula with three-point coordinate method to calculate the centre of circle is given,which is easy to program and calculate.To determine the third point position in the case of the certainty of two points,and three point optimal configuration is proven theoretically in detail,and accurate calculation as well as analysis are made from many aspects.The result indicates that three point configuration has larger influence on accuracy of the center of circle position;the measurement accuracy can be improved by selecting better configuration.It is operated quite well in the measurement of steel casing center position of Sutong Bridge.

Key words: steel casing, measurement, three point coordinate methods, accuracy analysis

摘要： 给出了一种易于编程计算的三点坐标计算圆心坐标的简捷公式。对两点一定的情况下第三点位置的确定及三点最佳构形进行了详细的理论证明,并进行了多方面的精度计算与分析。结果表明,三点构形对测量圆心的精度影响较大,选择合适的构形,可以提高测量精度。在苏通大桥钢护筒中心位置检测中得到了较好的应用。

关键词: 钢护筒, 检测, 三点坐标法, 精度分析