Sprayer boom motion, part 2: Validation of the model and effect of boom vibration on spray liquid deposition

Experimental work is reported here, which was carried out on a hydraulic shaker, to verify the black-box system identification procedure developed in Part 1 of the paper. A linear parametric transfer function model of the spray boom has been identified from an experimental input-output data set based on the frequency domain maximum likelihood estimator. Since the accuracy of the model depends strongly on the quality of the data records, much attention is paid in this paper to the design of the experiment: three different reference signals and two types of transducers for both input and output have been tested. All data sets have been compared to evaluate the ability to obtain accurate frequency response functions in the frequency band of interest (0-5 Hz). Longitudinal and vertical boom motion could be accurately described by a linear low-order model structure. Subsequently, the models were thoroughly validated with a simulation experiment. Finally, to evaluate the effect of boom movements on the spray deposit distribution, vibrations at the boom tip are simulated with the experimental models for realistic inputs. The corresponding spray deposition is generated with a liquid simulation program. From these simulations, it is concluded that both the rolling motion and horizontal vibrations of the boom can severely disturb the spray deposition pattern. (C) 2000 Silsoe Research Institute.