An innovative autonomous ground mobile unit for the precision physical weed control . Report 1842

In this paper the design, the main characteristics and the automation systems of innovative autonomous ground mobile units (GMU) for physical weed control (PWC) in maize are described. The machine will be created within the activities of the European Project RHEA (Robot fleets for Highly Effective Agriculture and forestry management), that aims to produce different prototypes of autonomous terrestrial and aerial robot able to perform several activities related to the general crop protection in different agricultural scenarios. The first autonomous ground unit machine was designed in order to perform a mechanical and thermal treatment removing weeds from the inter-row crop space and applying in-row selective and precision flaming by means of two crossed LPG rod burners. By means of some modifications of the tools it will be possible to realize also an autonomous unit for the precision broadcast flaming application. In this case the design involves a replacement of the mechanical tools working in the inter-row space with 50 cm wide burners able to perform flaming at different intensities according to weed cover detected by the perception system of the robot. The working width of both the PWC machines will be of 4.5 m, thus covering five entire maize inter-row spaces of 0.75 m each and 2 half inter-row space of 0.375 m each. The correct position of the tools (mechanical and thermal) will be guaranteed by an automatic precision guidance system connected and supervised to an image based row detection system. Each working elements will be provided by two crossed 0.25 m wide rod burners, hitting one side of each crop row. The flame should hit the weeds growing in the “inrow” space (a 0.25 m wide strip of soil with the maize plant in the middle). Regarding the control of the weed emerged in the “inter-row” space each working unit of the will be provided with rigid tools (one central foot-goose and two side “L” shaped sweeps). The mechanical treatment will be performed, independently from the weed presence, as hoeing is a very important agronomical practice. On the contrary, broadcast flaming in the inter-row space will be performed after weed detection, using three different LPG pressures and doses according to weed cover (no weed cover-no treatment, weed cover between 0 and 25%-flaming at 0.3 MPa, weed cover higher than 25%-flaming at 0.4 MPa). This very innovative application of precision PWC in maize could represent not only a good opportunity for farmers in term of herbicide use reduction, but also an environmental friendly and energy saving application of flaming in organic farming.