Mechanical within-row weed control for transplanted crops using computer vision

Environmental and commercial pressures are pushing vegetable and salad growers away from a reliance on herbicides. Whilst inter-row cultivation provides a relatively efficient method of removing weeds between crop rows, hand labour is often required to remove weeds within rows. A machine vision guidance has been used to address the problem of mechanically removing weeds within rows of transplanted vegetables and salads. The experimental machine was based on a commercially available steerage hoe equipped with conventional inter-row cultivation blades. It was also fitted with two novel shallow cultivation modules acting within crop rows. Each module featured a hydraulically driven disc rotating about a substantially vertical axis. Each disc had an interior section cut away to allow crop plants to pass undamaged. A vision system detected the phase of approaching plants and that information was combined with measured disc rotation to calculate a phase error between the next plant and disc cut-out. This phase error was corrected by advancing or retarding the hydraulic drive enabling synchronisation of the mechanism even in the presence of crop spacing variability. Field trials in transplanted cabbage indicated that under normal commercial growing conditions crop damage levels were low with weed reductions in the range 62–87% measured within a 240 mm radius zone around crop plants.