Highlights Spray droplet characteristics for 3DN 08 nozzles were investigated at 275, 345, 414, and 482 kPa. Backward spray direction from 3D nozzles may be exploited to compensate for mechanical valve latency. Spray droplet characteristics were tested for different criteria to optimize spot spraying based on system pressure. 275 kPa was found to be the best system pressure choice for spot application schemes. ABSTRACT. The use of machine vision technologies for pest detection in agriculture presents one decision-making tool for real-time spot applications. However, challenges associated with accurate spraying with respect to high ground speed still prevail. For example, when the machine vision system is placed on the same boom of the nozzles, high ground speeds may result in inaccurate spraying due to delays caused by machine vision processing time as well as valve-nozzle response. In this regard, the delays may be compensated by using 3D nozzles (nozzles that spray forward/backward). Therefore, this study was conducted to (1) exploit backward spraying from 3D spray nozzles to compensate for spray valve latency delays in real-time machine vision-based spot applications, (2) optimize spray characteristics affected by atomization factors such as system pressure and enhance deposition while simultaneously ensuring adhesion when nozzles are operated individually, and (3) ensure spray uniformity and investigate droplet collision outcomes when 3D spray nozzles are overlapped at different system pressures. Experiments were conducted using cameras to visualize spray characteristics at 275, 345, 414, and 482 kPa system pressure. Results demonstrated that backward spray direction from 3D nozzles may be exploited to compensate for mechanical valve latency even in overlapped spray scenario conditions, which would be essential in real-time spot applications after pest detection prompts spray commands. Results further showed that each spray characteristic can be accepted/rejected to improve deposition while enriching adhesion. Statistical analyses and/or thresholds have been used to optimize spray characteristics based on system pressure. In this study, 275 kPa was the preferred system pressure option. Keywords: Atomization, Nozzle tip, Precision agriculture, Spot application, Spray characteristics.
Maambo et al. (Thu,) studied this question.