Recently, the technique of image processing has been used for many purposes. This report is concerned with the flow pattern and level control of a hopper by using an image processing apparatus.
The flow pattern of granules inside the hopper changes at the transitional bed height (H_tr). H_tr is the bed height at which flow pattern of granules changes from mass flow to core flow or vice versa. The flow pattern of granules is uniform in the upperpart of H_tr. In this sense, it is easy to control the level of the hopper, because the surface of granules in the hopper is kept constant.
The flow pattern was first observed by using a video camera and image processing unit. The position of H_tr was measured. Then, the bed height of the hopper was controlled at the upper part of H_tr. The time to operate the image and to transmit the image data to a personal computer, and which is necessary for the image processing, was reduced to maintain good response waves. In order to do so, the area used for data processing of the flow pattern decreased, and the method of extracting useful information from the image data is discussed.
As for the results, we could obtain good response waves in the level control of hopper.