The objective of this study was to model mathematically and to simulate the dynamic behavior of an auger-type fertilizer applicator (AFA) in order to use the variable-rate application (VRA) and reduce the coefficient of variation (CV) of the application, proposing an angular speed controller ((theta) over dot) for the motor drive shaft. The input model was (theta) over dot and the response was the fertilizer mass flow, due to the construction, density of fertilizer, fill factor and the end position of the auger. The model was used to simulate a control system in open loop, with an electric drive for AFA using an armature voltage (V-A) controller. By introducing a sinusoidal excitation signal in V-A with amplitude and delay phase optimized and varying (theta) over dot during an operation cycle, it is obtained a reduction of 29.8 in the CV (constant V-A) to 11.4. The development of the mathematical model was a first step towards the introduction of electric drive systems and closed loop control for the implementation of AFA with low CV in VRA.
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