Practical rotation angle measurement method by monocular vision

A practical vision-based method is proposed to measure single axis rotation angles. Compared with existing angle measurement methods, the proposed method is more practical because of the simple equipment required and an easy installation. Furthermore, unlike most existing methods, the proposed method does not require the rotation axis information at all. The information is calibrated by two-view geometry of the single axis motion. Then, on the basis of the calibration results, an angle estimation algorithm with point matching is proposed. Experiments on synthetic and real images show that the proposed method is robust with respect to image noises and occlusion. A measurement accuracy of less than 0.1° is obtained in real experiments only using a provided camera and a normal printed checkboard. Moreover, a single axis rotation angle measurement MATLAB toolbox is developed, which is available online (http://quanquan.buaa.edu.cn/Anglemeasurementtoolbox.html).