17
5.2.2
Boom Stability in Crop
In general the top of the crop is a more inherently variable target than soil.
To put it simply, given identical control settings, your height control would
be more active when operating in
CROP
mode than in
SOIL
mode. To
allow for this, many settings are customized automatically when you change
modes on the UC4+ control panel. This is designed to provide a more stable
response in
CROP
mode. The tradeoff is that the system will also be
slightly slower to respond in
CROP
mode than in
SOIL
mode.
5.2.3
Thin Crop
The UC4+ ultrasonic sensors operate by bouncing sound waves off the
desired target. A minimum signal level is required from the crop in order to
use it for control purposes. This is no different than the fact that your radio
must be at a certain minimum volume level before you can physically hear it.
Different types of crop, and crops at different stages of development return
varying levels of sound. The following are some general guidelines.
•
Crops in growing stages are relatively good sonic targets.
•
Bearded crops are relatively poor sonic targets.
•
In row crops, the sensor must be positioned over the row to use the
crop signal, or between the rows to use the ground signal.
•
The desired target must cover roughly 60 percent of the area to be
tracked consistently. That is, when looking at the ground, the heads
should cover about 60 percent of the ground. Otherwise, you can
use
SOIL
mode.
•
If the sensor runs too close to the heads, they may not return enough
signal to be seen, or they may be blanked out. The nozzles must be
at least 55 cm (22 inches) from the crop. Slightly higher target
height settings will work better in thin crop.
5.2.4
Main Boom Sensor in Wheel Track
The required location for the main boom sensor is determined by the UC4+
Installation Manual for your sprayer and by the options you have installed.
Special attention is necessary when mounting the main boom sensor.
Mounting the main boom sensor directly behind a sprayer tire may impair
main lift control when operating in
CROP
mode. Height readings from crop
that is flattened by the sprayer wheel do not provide an accurate
measurement of canopy height, resulting in poor performance.
