Agriculture Reference
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that while traversing gently sloping land with high draft implements, implement
cross-track errors approached those of the guided tractor. Conversely, when pulling
low draft implements on sloping ground, cross-track errors can be 10 times that of
the tractor. Figure 5.3 provides a visual comparison of the difference between tractor
guidance and implement following errors.
In this investigation, it was common to see tractor cross-track errors less than
3 cm, but the corresponding implement cross-track error may be greater than 20 cm
depending on variations in terrain, and the relative draft forces of the various imple-
ments. Given the magnitude of the implement following errors, we now see commer-
cial solutions for guiding implements. The solutions range from active implement
guidance systems to mechanically steer the implement using hydraulic linkages
and Coulter disks. “Passive” implement guidance system steer the tractor to guide
Starfire antenna
(a)
70
60
50
40
30
20
10
*
0
Sensitivity
implement
1
2
1
3
1
2
2
3
1
2
3
3
GPS antenna on implement
(b)
70
*
60
50
40
*
30
*
20
10
0
Sensitivity
implement
1
2
1
3
1
2
2
3
1
2
3
3
Sensitivity: 1 = Lowest setting, 2 = Middle setting, 3 = Highest setting
Implement: 1 = Integral planter, 2 = Tillage tool, and 3 = Towed planter
FIGURE 5.3
Boxplot summary of cross-track error data from Veal et al. (2009): (a) Tractor
guidance cross-track error. (b) Implement following cross-track error. (Data from Veal, M.W.
et al.,
VDI-Berichte
, 2060, 193-198, 2009. With permission.)
