2D Rotation-Angle Measurement Utilizing Least Iterative Region Segmentation

Abstract

When geometric moments are used to measure the rotation-angle of plane workpieces, the same rotation angle would be obtained with dissimilar poses. Such a case would be shown as an error in an automatic sorting system. Here, we present an improved rotation-angle measurement method based on geometric moments, which is suitable for automatic sorting systems. The method can overcome this limitation to obtain accurate results. The accuracy, speed, and generality of this method are analyzed in detail. In addition, a rotation-angle measurement error model is established to study the effect of camera pose on the rotation-angle measurement accuracy. We find that a rotation-angle measurement error will occur with a non-ideal camera pose. Thus, a correction method is proposed to increase accuracy and reduce the measurement error caused by camera pose. Finally, an automatic sorting system is developed, and experiments are conducted to verify the effectiveness of our methods. The experimental results show that the rotation angles are accurately obtained and workpieces could be correctly placed by this system.

Special Issue on Visual Sensors

“…Some of the papers of the Special Issue revolve around this problem. In [33], the authors presented an improved rotation-angle measurement method based on geometric moments that is suitable for automatic sorting systems. In [34], a stereo vision system is employed for measuring the ram speed of steam hammers.…”

Plastic Optical Fiber Angle Sensor for 1-D and 2-D Based On Cascading Of TMBC

“…A straightforward approach to achieving the multi-dimensional angle sensor uses two or more sets of 1-D angle sensors, but this approach is straightforward and increases the system cost and complexity. A few works have been reported for 2-D angle sensor [30][31][32]. As far as we know, no two-dimensional angle sensor based on optical fiber has been reported so far with a maximum measuring range of 360º.…”