Agriculture Reference
In-Depth Information
and nighttime operation and active sensor systems have been investigated to meet
this challenge (e.g., Rees et al., 2009). Sensor fusion has been a way to minimize
sensor error and improve the reliability of measurements. Statistical approaches and
soft computing and learning techniques such as neural network, genetic algorithms,
and fuzzy logic can also be used to minimize the effect of uncertainties and nonuni-
formities of crops and the outdoor environment on sensor-based target identification
and localization.
10.4.6 A
UTO
-G
UIDANCE
AND
A
UTONOMOUS
O
PERATION
Automatic guidance and autonomous operation of agricultural machinery has been
an active area of research and development in the past two decades. GPS-based
navigation and guidance systems that can steer a vehicle automatically through a
predefined path have been successfully commercialized by various agricultural
equipment manufacturers as well as companies specializing in positioning and
navigation technologies. Auto-guidance technology helps achieve highly accurate
precision and VRA. Automatic guidance also takes the operator out of a tedious
task of steering a sprayer, so that (s)he can focus on other important tasks such as
monitoring chemical application. In open fields, RTK-GPS technology used by the
auto-guidance system can achieve about 2.5 cm (1 in) positional accuracy, which is
sufficient for practical precision application in many row crops. However, the GPS
signal is compromised if a crop field is surrounded by tall trees and artificial struc-
tures such as buildings. This issue becomes particularly important in perennial tree
fruit production, where fruit trees may block direct line of sight to GPS satellites and
can cause multipath effect to substantially reduce RTK-GPS accuracy.
Autonomous operations of agricultural equipment have also been successfully
tested in research operations. A combination of sensors including laser scanning,
stereo vision, and RTK-GPS is used to guide the vehicles and avoid obstacles and
collisions. However, commercialization of this technology is limited. Liability and
economic issues are two of the important constraints in commercial adoption of
autonomously operated agricultural equipment. Further improvement and compre-
hensive evaluation along with standardization and changes in regulatory policies are
essential to widen the adaptation of autonomous machines. If commercially adapted,
autonomous operation of a spraying system will remove the operator from the close
proximity of chemicals and substantially reduce the risk of chemical exposure to
workers.
10.5 CURRENT SITUATION AND FUTURE DIRECTION
Automation in chemical application systems have progressed significantly over the
past three decades. Various research and development efforts led by universities,
research institutes, and private industry resulted in technologies such as nozzle con-
trol, rate control, section control, and boom/tower control to achieve precise and uni-
form chemical application. Adoption of individual technolgies has been successful
in commercial scale. Application rate control has been adapted widely in different
types of crops. Steering control for automatic and autonomous guidance has been
