Agriculture Reference
In-Depth Information
Fig. 4.8
Shifting of the
target point on side slope
Fig. 4.9
The three-dimensional position of a tractor on a slope depends on topography and head-
ing. Topography defi nes the roll angle (side slope angle) and the pitch angle (down slope angle).
Heading depends on the guidance and is defi ned by the yaw angle, which is the deviation between
the path- and the tractor direction. This yaw angle may be close to zero on fl at land, but along side
slopes it may be not because the tractor crabs along the slope
fi xed line guidance along straight paths is practiced, the slope directions - side slope
or down slope - can vary. As a result, not only roll (side slope), but
pitch
(down
slope) and yaw of the tractor as well may need attention (Fig.
4.9
).
Ya w
is the head-
ing error of the tractor that may result from crabbing and slipping, especially on side
hills. Because of this, a deviation between the direction of the planned path and the
heading position of the tractor can exist.
Roll, pitch and yaw can be measured via GPS in order to adapt the guidance. In
case mainly the effects of
roll
are a problem - as with contour farming (Fig.
4.8
) -
the remedy is rather simple. If two antennas are mounted on the roof - one on the
