School of Automation, Chongqing University, Chongqing 400044, China.
Sensors (Basel). 2019 Apr 5;19(7):1634. doi: 10.3390/s19071634.
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.
当使用几何矩来测量平面工件的旋转角度时，即使工件的姿态不同，也会得到相同的旋转角度。在自动分拣系统中，这种情况会被视为错误。在这里，我们提出了一种基于几何矩的改进的旋转角度测量方法，适用于自动分拣系统。该方法可以克服这一限制，获得准确的结果。详细分析了该方法的准确性、速度和通用性。此外，还建立了一个旋转角度测量误差模型，以研究相机姿态对旋转角度测量精度的影响。我们发现，非理想的相机姿态会导致旋转角度测量误差。因此，提出了一种校正方法来提高精度，并减小由相机姿态引起的测量误差。最后，开发了一个自动分拣系统，并进行了实验验证我们方法的有效性。实验结果表明，该系统可以准确地获取旋转角度，并正确地放置工件。
