A mechanical device, the "canopy opener," is being designed to bend tops of soybean plants, creating a pathway for sprayed pest control agents into the lower crop canopy. Mathematical models were developed to aid opener design and placement to maximize spray penetration and coverage with minimum crop damage. The models established relationships among plant deflection, opener depth inside the canopy, and plant height, enabling determination of opening width based on calculations of plant-recovery motion after release from the opener and time available for droplet travel from the nozzle to the lower canopy. To provide parameters to support the developed model, natural frequencies and damping coefficients of soybean plants were determined experimentally. Additionally, times required for droplet travel from specific nozzles to the lower canopy were determined using a laser velocimetry system. The models predicted that for XR8004 nozzles at 276 kPa the maximal opener depth would be 0.14 m and the opener width should range from 0.04 to 0.47 m for 1.06 m tall soybean plants. Experimental measurement of maximal deflection and plant motion agreed with mathematical models.
