Real-time nozzle flow uniformity when using automatic section control on agricultural sprayers

• Published in: Computers and electronics in agriculture 2011-11, Vol.79 (2), p.169-179
• Main Authors: Sharda, Ajay, Fulton, John P, McDonald, Timothy P, Brodbeck, Christian J
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Compensation; Control systems; Distribution; environmental impact; Fundamental and applied biological sciences. Psychology; Liquid application; Nozzle flow; Nozzles; Precision agriculture; Reentry; Settling; Sprayers; Uniformity; Variability
• ISSN: 0168-1699; 1872-7107
• DOI: 10.1016/j.compag.2011.09.006

Automatic section control (ASC) has been readily adopted by US producers on sprayers because it can improve operator productivity and decrease overlap or input usage leading to economic savings while reducing environmental impacts. However, there is limited knowledge about nozzle flow dynamics when shutting ON/OFF of boom-sections or nozzles and the possible impact on application accuracy. Therefore, an investigation was conducted to evaluate system response in managing real-time nozzle off-rate and flow uniformity across the boom, for a typical agricultural sprayer using ASC. An 18.3-m sprayer was outfitted with commercially available individual nozzle and boom-section control. Tests were conducted to simulate sprayer moving out of point rows into a no-spray zone and then reentry into the spray zone by selecting two point row scenarios having 20° and 70° angles. Ten high frequency response pressure sensors were randomly mounted across the boom to measure nozzle pressure. The nozzle pressures were converted to nozzle flow, using the manufacturers pressure versus flow relationship, to calculate nozzle flow rate delay time, settling time, percent off-rate (percent difference between actual and target nozzle flow rate) and nozzle flow uniformity (CV), considering only ON boom-sections. Auto-boom scenarios were conducted with and with-out flow compensation while auto-nozzle scenarios were conducted without flow compensation. Results indicated that nozzle flow rate settling time varied from 0.4 to 14.4s and nozzle off-rate between 36.6% and +28.7% for 70° point row auto-boom tests when exiting and reentering point rows. When exiting point rows, over-application occurred whereas reentry resulted in under-application during flow compensated tests. Nozzle flow uniformity (CV) were more than 50% for a short duration (