PRECISION BAND SPRAYING WITH MACHINE-VISION GUIDANCE AND ADJUSTABLE YAW NOZZLES

A system was developed for precision, ground-based application of foli ar sprays to rows of small plants. The system consisted of a machine-v ision guidance system that positioned spray nozzles directly above eac h row of small plants. An electrically actuated mechanical linkage rot ated flat-fan spray nozzles about their central axes to vary the yaw a ngle of the fans relative to the direction of travel. The nozzle rotat ion effectively changed the width of the spray pattern relative to the direction of travel and allowed the spray band to be adjusted to matc h the width of the target plants. The system was evaluated on young st ands of tomatoes and lettuce by measuring spray deposition on the plan ts and surrounding soil. The precision system allowed spray applicatio n rates to be reduced by 66 to 80% and increased spray deposition effi ciency on the target plants by 2.5 to 3.7 times greater than conventio nal broadcast spraying. Nontarget deposition on soil surfaces was redu ced by 72% to 90%. Airborne displacement of spray liquid from the spra y boom, as measured by collection strings surrounding the boom structu re, was reduced by 62 to 93%. The reduction in displacement suggested that spray drift from precision applications could be significantly le ss than that from conventional applications.