Design and full realization of physical weed control (PWC) automated machine within the RHEA project

Currently precision agriculture can rely on modern technologies that allow to design and realize operative machines provided with perception systems, in order to perform precise and targeted treatments. The ultimate objective of this synergy consists in reducing the use of agrochemicals and energy, enhancing the sustainability of agricultural practices. In this regard, the RHEA project funded by EU, aims to develop a fleet of etherogenous autonomous robot units in order to perform precise treatments related to crop protection in different scenarios. In this paper is reported the design and the development of an automatic machines able to perform, at the same time, mechanical and thermal weed control on maize is described and discussed. The equipment will be coupled to an autonomous ground mobile unit equipped with a row and a weed detection systems. The operative machines was designed to remove weeds mechanically from the inter-row spaces of the crop and perform selective and targeted cross flaming, in the rows of the crop. The precision of the treatment is ensured by specific vision based perception system for weed detection and crop row detection. Mechanical treatment (inter-row cultivation) will be performed in a continuous way, even without weed presence. The machine is provided with a guidance system managed by a crop row detection system in order to avoid damaging the maize plants with the rigid tools used for mechanical weed removal. On the contrary cross flaming on the rows of the crop is actuated only if weed patches are detected. The thermal weed control is applied by mean of couples of rod burners LPG fed, able to treat a 25 cm wide strips with the crop row in the middle. The biological selectivity is ensured by maize high tolerance and weeds sensitivity to flame exposure for few tenths of seconds. Moreover, the LPG working pressure can be adjusted according to the level of weed cover detected by the weed detection system: - no treatment, if weed cover is near to 0 %; - low LPG working pressure, if weed cover is lower than 25%; - high LPG working pressure, if weed cover is higher than 25%. Each unit for thermal weed control is provided with an ignition system able to properly swich on the burners at the selected LPG working pressure. This ignition system enables to avoid the use of pilot light, often adopted in the conventional “low-tech” flaming machines. This fact is very important for the overall safety of the system, since the implement is coupled with an unmanned ground mobile unit