Several developments and investigations have been done to automate the lateral control of hoes
with the aim to achieve higher weeding efficiency and decreased labor costs. The aim of this
project was to investigate the accuracy and limitations for a computer controlled hoeing
operation based on a GPS system. A conventional hoe and an electro-hydraulic side shift frame
was used and attached to a small automatic tractor. The main task of the controller systems was
to minimize the lateral deviations between current GPS positions of the hoe related to a
predefined route. The range of the cross track errors (standard deviations) altered between 0.009
m and 0.028 m for the hoe (ground measurements). The hoe system enables hoeing up to 83% of
a field surface area with a speed of 2 km/h and up to 79% by driving with 4 km/h. The GPS
based system showed its potential to be used for high accurate crop row guidance e.g. with an
inter-row hoe. Further research should be carried out to investigate sensor fusion systems
consisting of GPS and other sensors e.g. based on computer vision.