Variable rate fertilisation: Measurement of fertilizer granules motion on a centrifugal spreader by image analysis

Although mechanically simple, centrifugal spreaders used for mineral fertilization involve complexphysics that cannot be fully characterized at the present time. We are developing sensors to evaluatethe spatial distribution of the fertilizer on the ground based on the measurement of initial flightconditions of fertilizer granules after their ejection by the spreading disk. The techniques developedare based on the analysis of images of the area around the disk showing the granule ejection. A fastimaging technique developed for this specific purpose is presented in this paper. It allows toautomatically compute the direction of ejection and velocity of each granule observed in the image.