The Rhea Project: a fleet of autonomous robot able to perform physical weed control in herbaceous and vegetable crops.

Promoting the sustainable use of agrochemicals is a recent issue of the European Union. In this respect, both the “alternative” equipments (for instance the machines for physical weed control) and the recent applications of precision farming may play an important role. The European Project RHEA (Robot fleets for Higly Effective Agriculture and forestry management) fits into this context and aims to realize a fleet of autonomous aerial and ground mobile units for crop protection. The purpose of the aerial units will be to “inspect” the field and send information to the operative base, which will plan accordingly the path for the ground units. They will be characterized by an autonomous tractor coupled with an “intelligent” operative machine. Three actuation systems will be developed, according to three different scenarios: herbicide application in wheat; physical weed control in maize and on-canopy insecticide application in olive trees. This work describes the precision hoe designed to perform mechanical and thermal weed control in maize. The machine will be equipped with rigid elements for a shallow soil cultivation (till 5 cm of depth at maximum) between the rows and couples of burners for selective in-row flaming, as maize is tolerant to the thermal shock. In order to enhance the precision of the treatment, the hoe will be equipped with directional wheels connected to an electronic row detection system. The thermal treatment will be performed only in case of weed detection by the perception system of the aerial and ground unit, while the mechanical treatment will be performed independently from weed presence. The LPG dose per surface unit (hence the intensity of heat transfer) will be adjusted according to the level of weed canopy, which will be detected separately in the different bands where the burners will operate