Image-based Measurement of the Surface Profile of the Cascading Granular Materials in Rotating Cylinders

摘要

Cascading granular motion is dominant in rotary mixers. A measuring system is introduced to capture the surface profile of the cascading material bed based on image processing technology. The images of the bed are processed using Matlab programs, including filtering, image segmentation, dilation, erosion, edge detection and separation. The Cartesian coordinates of each point on the profile are saved automatically in computer. The effectiveness of this method is verified by experiments on a rotating cylinder using rice as material. A 640(480 sized image can be processed in about one second. Experimental results demonstrate that, the slope of the upper half of the surface increases with increasing rotation speed, whereas the lower half of the surface keeps approximately constant. The area of the material bed is only slightly increased by 8% as the speed of the rotating cylinder is doubled.