Amélioration des dépôs de pulvérisation par recours à un contrôleur PWM pour compenser les mouvements horizontaux de rampe de pulvérisation

摘要

Longitudinal spray distribution is mainly affected by the horizontal speed variations of the nozzles.Manufacturers classically try to reduce unwanted nozzles movements using horizontal boomsuspension but these methods have performance and price limitations. This paper describes a spraycontroller aiming to compensate the effect of the horizontal boom movements on the spray depositshomogeneity. The controller is based on three main components: a control law describing the relationshipbetween nozzle speed, nozzle flow and spray deposit; a real time measurement of the boomhorizontal speed variations using micro-machined capacitive accelerometers, and pulse width modulation(PWM) nozzle flow actuators. To assess the feasibility of such a controller, a single nozzleprototype was developed and tested in the laboratory, using a nigrosine solution. Spray coveragewas measured using image analysis for field representative nozzle speed variations. The spray coverageuniformity using the controller showed about 51% compensation of the variations observedwithout it.