椭圆拟合算法在硅橡胶憎水性检测应用中影响因素的研究

Factors Influencing the Application of Ellipse Fitting Algorithm in Silicone Rubber Hydrophobicity Detection

为了快速提高椭圆拟合算法计算接触角的速度和精确度,实验分析了多种因素对算法精确度和实时性的影响。结果表明:拟合点数选择5个即可;选择的拟合点应在水珠边缘圆弧上近似均匀分布,当选择点偏向一端时误差急剧增加;随着噪声含量的增加误差增大,含噪时应选择5个边缘点然后对多次选择边缘点的计算结果求平均,可很大程度上减少误差;椭圆图像圆拟合算法稳定性虽高但误差仍不小,且误差随离心率的增加而增大,所得结果比真实值偏小。圆和椭圆拟合算法获得接触角所需时间主要为取点时间,随着取点数增加耗时增大。

For improving speed and accuracy of fast ellipse fitting algorithm for contact angle calculation,the influence of various factors on algorithm accuracy and real-time performance was analyzed by experiment.The result indicates that： five fitting points is enough.The selected points should be nearly uniform distributed around the globule edge,if selected points are concentrated then the error of contact angle calculation will increase badly.The error of measurement will increase with the increase of noise,then five edge points should be selected,and the mean value of multiple calculations can be used to decrease error. As for ellipse figure,circle fitting algorithm has good stability but still has large error,and the error will increase with the increase of eccentricity,the calculated value is less than the real value.Time for selecting edge point is the main cost when circle or ellipse algorithm is selected in which time consuming will increase with the increase of selected point number.