Precision Band Spraying With Machine-Vision Guidance and Adjustable Yaw Nozzles

A system was developed for precision, ground-based application of foliar sprays to rows of small plants. Thesystem consisted of a machine-vision guidance system that positioned spray nozzles directly above each row of smallplants. An electrically actuated mechanical linkage rotated flat-fan spray nozzles about their central axes to vary the yawangle of the fans relative to the direction of travel. The nozzle rotation effectively changed the width of the spray patternrelative to the direction of travel and allowed the spray band to be adjusted to match the width of the target plants. Thesystem was evaluated on young stands of tomatoes and lettuce by measuring spray deposition on the plants andsurrounding soil. The precision system allowed spray application rates to be reduced by 66 to 80% and increased spraydeposition efficiency on the target plants by 2.5 to 3.7 times greater than conventional broadcast spraying. Nontargetdeposition on soil surfaces was reduced by 72% to 90%. Airborne displacement of spray liquid from the spray boom, asmeasured by collection strings surrounding the boom structure, was reduced by 62 to 93%. The reduction in displacementsuggested that spray drift from precision applications could be significantly less than that from conventional applications.