Abstract—In this paper we present a visual odometry system
for agricultural field robots that is not sensitive to uneven
terrain. A stereo camera system is mounted perpendicular to
the ground and height and traveled distance are calculated
using normalized cross correlation. A method for evaluating the
system is developed, where flower boxes containing
representative surfaces are placed in a metal-working lathe.
The cameras are mounted on the carriage which can be
positioned manually with 0.1 mm accuracy. Images are
captured every 10 mm over 700 mm. The tests are performed on
eight different surfaces representing real world situations. The
resulting error is less than 0.6% of traveled distance on surfaces
where the maximum height variation is measured to 96 mm.
The variance is measured for eight test runs, total 5.6 m, to
0.040 mm. This accuracy is sufficient for crop-scale agricultural
operations.