空间圆姿态识别二义性的角度约束消除

为了消除视觉测量中单个圆姿态识别中存在二义性的问题,提出了一种基于空间角度约束消除二义性的方法,并且对姿态求解算法进行了误差分析,为准确进行姿态估算给出了指导性的实验结果。在摄像机已标定的前提下,根据圆特征在图像上的投影椭圆曲线确定了圆心位置和圆平面姿态参数,计算结果存在二义性;利用欧式空间中的角度不变量,识别出圆平面的真实姿态参数,同时确定圆心的真实位置;最后,根据误差传播理论对基于单圆特征的位姿估计算法进行了精度分析。实验结果表明,圆平面姿态角的测量绝对误差在0.2°以内,圆心的定位误差为0.5%,根据圆平面的位姿参数计算的共面直线的距离误差为0.8%。该方法能够准确地识别圆平面的位置和姿态,计算过程简单,结果稳定可靠且具有较高的精度。

Solution of duality in pose estimation of single circle using Euclidean angular constraint

In order to solve the duality problem in pose estimation of a single circle in machine vision, an approach based on Euclidean angular constraint is presented to identify the unique pose result. The accuracy of pose estimation is analyzed, which provides constructive suggestions on achieving accurate pose estimation of circles based on experimental results. The pose of single circle is recovered from its projection in an image with a calibrated camera, though the result is ambiguous, only two possible results exist. Then, the unique pose is identified based on the Euclidean angular invariant. Finally, the accuracy of pose estimation is analyzed based on the theory of error propagation. Experimental results indicate that the absolute error of pose angle of the circle plane and the relative error of position determination are within 0.2°and 0.5% m respectively,and the absolute error of reconstructed distance between the two lines is within 0.8%. These results show that the approach can identify correctively poses and positions of circle planes and can offer a high measuring accuracy and reliable results by a simple computing process.