An efficient vision system to measure granule velocity and mass flow distribution in fertiliser centrifugal spreading

This article reports a new approach to measure the velocity and the mass flow distribution of granules in the vicinity of a spinning disc in order to improve fertiliser spreading in agriculture. In this approach, the acquisition system consists of a digital camera placed above the disc so that its view axis corresponds to the disc axle. This provides useful geometrical properties to develop a simple and efficient image processing. A specific Hough transform is implemented to extract relevant data (polar coordinates of granule trajectory with respect to the disc centre) from granule streaks deduced from “motion-blurred images”. The Hough space directly provides the mean-radius of the polar coordinates of the trajectories from which the mean value of the outlet velocity is deduced. The Hough space also provides the angular distribution of the trajectories from which an estimation of the mass flow distribution is deduced. Results are compared with those obtained with reference methods.