Agriculture Reference
In-Depth Information
used laser sensors to detect citrus canopy size and density. Balsari et al. (2008) used
ultrasonic sensors in apple trees to estimate canopy characteristics for regulating the
application rate. Jeon et al. (2011) developed an over-the-row, dual-sided, platform
sprayer with ultrasonic sensors connected to each nozzle. The application rate was
calculated in real time based on those sensors.
Higher density and resolution of canopy measurement is achieved by color cam-
eras and other imaging sensors. A charge-coupled device camera-based sensing sys-
tem can be used to detect and identify pests (e.g., weed) and plant parts. This type of
sensing systems depends on color-based segmentation, shape and texture analysis,
and stereo vision. A real-time three-dimensional (3-D) imaging sensor can also pro-
vide the location of target pests or plants (Nakarmi and Tang, 2010; Adhikari and
Karkee, 2011). Improved segmentation may be achieved through the use of multi-
spectral or hyperspectral cameras (Wang et al., 2001; Rees et al., 2009).
Various sensors and actuators are utilized in automated chemical applications
systems. These sensors are located in different spatial locations based on their use
in specific automation systems (Figure 10.7). Electrical control units, not shown in
Figure 10.7, process the inputs from respective sensors and produce the desired func-
tion of the corresponding actuator in each system. Although components are shown
on a self-propelled, row crop-type sprayer, the functionalities of the components can
be extrapolated to specialty crop spraying systems.
Outdoor lighting conditions have been a major challenge in vision-based plant and
pest identification and localization systems (Tang et al., 2000b). Controlled lighting
Global positioning system
Autosteer
Section control
Variable rate
Automation
sensors
Nozzle flow meter
Droplet size control
Variable rate
Pressure gauge
Droplet size
control
Flow meter
Rate control
Speed sensor
Rate control
Active crop
sensor
Variable rate
Boom height sensor
Auto height control
FIGURE 10.7
Simplified graphical representation of fundamental sensing components of
multiple automated chemical application systems. An automation system utilizing each sens-
ing component is listed.
