Dk. Giles et Dc. Slaughter, PRECISION BAND SPRAYING WITH MACHINE-VISION GUIDANCE AND ADJUSTABLE YAW NOZZLES, Transactions of the ASAE, 40(1), 1997, pp. 29-36
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.