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Real-Time Pressure and Flow Response for Swath Control Technology

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2009 Reno, Nevada, June 21 - June 24, 2009  097320.(doi:10.13031/2013.28894)
Authors:   Ajay Sharda, John P Fulton, Timothy P McDonald, Matthew Darr, Wesley C Zech, Christian J Brodbeck
Keywords:   Liquid application, precision agriculture, distribution, uniformity, pressure, variable-rate technology

Auto-swath technology is being readily adopted by producers across the US because it can improve in-field equipment efficiency and reduce input usage leading to economic savings. Spray controllers with swath control use GPS to track of areas where inputs have already been applied and areas identified to receive no inputs. However, concerns exist for liquid applicators equipped with auto-swath technology about the system response when shutting ON/OFF of boom-sections or nozzles possibly impacting the desired spray pattern and rate. Therefore, an investigation was conducted to evaluate real-time boom dynamics, pressure and flow, for a typical agricultural sprayer using auto-swath technology. An 18.3-m sprayer was outfitted with commercially available individual nozzle and boom-section control was used to determine if difference existed between these different methods of ON/OFF control. Ten high frequency response pressure sensors were randomly mounted across the boom to measure nozzle tip pressure with another sensor located at the boom manifold to record overall system pressure. A flow meter just before the boom manifold provided system flow response. Two point row scenarios having 20 and 70 angles were conducted at 43.2 l/min application rate and 9.7 km/h ground speed. Auto-boom scenarios were conducted with and with-out flow compensation while auto-nozzle scenarios were conducted without flow compensation. Results indicated that 1) pressure deviation between -28% and 29% during 20 and 70 point row auto-boom scenarios resulted in the spray tip flow rate varying from -19.2% to 12.4 % during auto-boom scenarios; 2) nozzle pressure stabilization time (PST) was up to 19.3 sec. while moving OUT and INTO point rows,; 3) 20 point row presented an example of a scenario where the controller was unable to control the application rate during auto-swath initiation; and 4) the sprayer system dynamics were different for moving INTO versus OUT of point rows for all tests. These results suggest different control algorithms and possible hardware improvements are needed for these operating conditions to minimize application errors.

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