The robots had to navigate the track in a figure 8, following
the outer line. If they drifted off into a center square, they
Two robots were placed on the track at a time, starting at opposite ends.
Collision detection and handling were thus added to the problems of
following the white line in the correct pattern.
The robot's "brain" was a 68HC11 chip in a basic Rugwarrior-like
board. The robot was powered by rechargable Nicad
Inputs to the board were a serial cable with modular plug (from
the computer) and a power input (to recharge the battery). The
chip was programmed with Interactive C.
The robot sensed the white line through a combination of IR emitters
and detectors. In addition there was a larger IR detector for
detecting the start signal. There was also a bump switch, which
could be used for collision detection.
Outputs from the board included some LEDs for diagnosis and a speaker.
Navigating the track
The robots had two LEGO motors each, which could be driven in forward
or reverse independently. Information gathered by the sensors was
processed to determine motor actions, thus producing appropriate
If a robot lost the white line, it might be able to pick it up again
(but not always facing the right direction).
Handling a junction
The junctions posed two problems - detecting a fork in the line, and
correctly deciding which fork to take. A robot which took the wrong
fork was deemed disqualified.
The robots were to do three laps of the track, which meant
6 junction decision points had to be passed correctly.