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5.4 Case Study: Unmanned Ground Robotics Competition

Figure 5.4 Omnibot, a mobile robot built from a Power Wheels battery-powered toy
jeep by students and Omnitech Robotics, Inc.

Step 3: Describe the Environment. This step is critical for two reasons.
First, it is a key factor in determining the situatedness of the robot. Second, it
identifies perceptual opportunities for the behaviors, both in how a percep-
tual event will instantiate a new behavior, and in how the perceptual schema
for a behavior will function. Recall from Chapter 4 that the Reactive Para-
digm favors direct perception or affordance-based perception because it has
a rapid execution time and involves no reasoning or memory.
The course was laid out on a grassy field with gentle slopes. The course consisted
of a 10 foot wide lane marked in US Department of Transportation white paint,
roughly in the shape of a kidney (see Fig. 5.5). The exact length of the course and
layout of obstacles of the course were not known until the day of the competition, and
teams were not permitted to measure the course or run trials on it. Obstacles were all
stationary and consisted of bales of hay wrapped in either white or red plastic. The
bales were approximately 2 ft by 4 ft and never extended more than 3 feet into the
lane. The sonar was able to reliably detect the plastic covered bales at most angles of
approach at 8 feet away. The vehicles were scheduled to run between 9am and 5pm
on May 22, regardless of weather or cloud cover. In addition to the visual challenges
of changing lighting due to clouds, the bales introduced shadows on the white lines
between 9–11am and 3–5pm. The sand pit was only 4 feet long and placed on a
straight segment of the course.
The analysis of the environment offered a simplification of the task. The placing of
the obstacles left a 4 ft wide open area. Since Omnibot was only 3 ft wide, the course
could be treated as having no obstacles if the robot could stay in the center of the lane