Flow and Pressure Regulation for Agricultural Sprayers Using Solenoid Valves * *This work was supported by the CNPq under grant 306.477/2013-0 and the Empresa Brasileira de Pesquisa Agropecuária (Embrapa Instrumentação) under Project MP2 No. 02.11.07.0.25.00.00

Abstract This work deals with the problem of controlling the application rate from prescribed maps and regulating the pressure on the sprayer booms in precision agriculture. In spraying, the droplet size is related to the application quality which is affected by the type of nozzle and the operating pressure on the sprayer boom. However, as the pressure is dependent on the flow, using conventional nozzles the flow can not be controlled without changing the pressure. It is proposed to control a set of solenoid valves according to an established sequence which yields the desired flow. The control is based on the calculation of the fluidic resistance of solenoid valves to provide the desired flow rate while maintaining the pressure on the booms within acceptable limits to keep the drop size. A sprayer is simulated with commercial nozzles and also preliminary experimental control results of a set of solenoid valves via an industrial network are presented to validate the proposed approach.