PCC MarchApril Final Draft

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canopies is used to determine the presence
of a plant canopy and measure the
canopy height, width, foliage density
and canopy foliage volume (Figure 2).
The GPS navigation device (or the radar
speed sensor mounted at the bottom
of the sprayer) measures sprayer travel
speeds and location of each plant in the
field. Based on the plant canopy foliage
volume and the sprayer ground speed,
the amount of spray for each nozzle
is determined and then discharged
to different parts of each plant in real
time. Each nozzle is connected to a 10
Hz pulse width modulation (PWM) solenoid
valve, and the nozzle flow rates
are controlled by manipulating the
duty cycle of the PWM waveforms with
the flow controller. The flow controller
consists of microprocessors to generate
flow rate commands for each nozzle
to discharge variable spray rates. Field
data collected and processed with the
intelligent spray system are synchronized
through the tablet WiFi to the
cloud.
The Android tablet provides the information
for operators to communicate
with the spray control system. The
screen displays the sprayer travel speed,
total discharged spray volume, spray
width, and active nozzles. The operator
can use the touch screen to modify
the spray parameters as needed. The
tablet allows the operator to activate
the sprayer output on one or both sides
in manual or automatic mode. All the
electronic devices are powered by a 12V
DC tractor battery. Another precaution
includes the air filtration unit to discharge
filtered air to prevent the laser
sensor surface from getting dust and
droplets. The toggle switches on the
switch box are used to turn on/off main
power, turn on/off the air filtration unit
manually and override the automatic
controller to activate nozzles as needed.
Because sprayer travel speeds are automatically
measured and included in the
spray output control, applicators do not
need to specify how fast they drive the
tractor. However, travel speeds are not
Figure 2. Laser sensor signals are used to measure canopy architecture and then manipulate
individual nozzle flow rates as the function of the sectional canopy foliage volume and
travel speed in real time.
suggested to be higher than 5 MPH for
orchard spray applications.
Features in the commercial system also
include tree counting, tree size, foliage
density heat map comparison capability,
liquid volume sprayed per plant,
maps of sprayed plant locations, ability
to turn nozzles on/off independently
through the tablet screen, cloud sync
feature, web portal for configuration
settings and spray coverage report view,
system log files, five different languages
(English, Spanish, French, German and
Italian), and options for choosing metric
or imperial units. The commercial
products have been used by growers in
the US and other countries with crops
including citrus, nursery, pecan, blueberry,
peach, almond, apple and pear
with pesticide usage reductions in the
range between 30% to 85% depending
on crop types and growth stages. John
Deere also established an agreement
with Smart Guided Systems to sell the
commercial intelligent spray control
system for use in high-value crop applications
through their dealer network.
The intelligent spray control system advances
conventional standard pesticide
application systems with the flexibility
to spray specific positions on the plants.
It reduces human involvement in
decisions on how much spray volume
is needed because the spray volume
applied in the field is automatically
controlled by the plant foliage volume
instead of the antiquated gallons per
acre.
The conventional air-blast spray system
has been used from generation to generation
for almost 80 years because of
its robustness. Growers have accumulated
extensive experience on using it to
control pests in accommodation with
their own crops. After being retrofitted
with the intelligent spray control
system, the conventional sprayers are
able to turn on and off each nozzle and
will stop spraying non-target areas such
as gaps between trees, on the ground
and above trees while their capabilities
of spray penetration, spray range
and spray deposition quality on plants
remain the same. This new generation
of spray technology is anticipated to be
a primary precision spray technology
for future decades to save chemicals for
growers and provide a sustainable and
environmentally responsible approach
to protecting crops.
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article@jcsmarketinginc.com
6 Progressive Crop Consultant March / April 2021