MathCS - Robotics

Challenge: Follow the Black Brick Road

In this challenge your robot needs to successfully follow a black line taped onto a light background without any intervention. The taped black line will be at least 1 inch wide, it will not intersect itself, it will form a closed loop, and it will form a smooth curve with a curvature no larger than that of the black oval on the NXT “test pad” (i.e. it will “curve less” than the test pad).

You may set your robot down anywhere with any heading. Once you start your robot you may not touch it other than to turn it off. Your robot needs to traverse the closed loop at least twice, but it does not need to stop by itself – you could turn it off manually after it completes two rounds.

One possible “follow the line” path

Your programming environment can be either NXT-G, LeJOS, or MS Robotics Studio, but NXT-G is recommended for this assignment.


You must be successful in at least 1 of 2 trials and you have 10 minutes to prepare after learning the course layout. You lose 10 points each you need to manually adjust your robot if it loses its bearings. The team with the fastest time to complete the challenge properly receives 5 bonus points.

Note: You could use the NXT test pad oval to practice, but it does not form a closed loop because of the “start” area. If your robot can follow the oval properly and only gets confused in the “start” area, you will probably be fine. Note also that the true course will have a thicker black line than the test pad, which should make it easier for your robot to stay on-track.

You might want to calibrate the black/white reading of your light sensor to adjust for possibly different lighting conditions prior to starting your run.

Results from 10/01/2008:

The path was marked on a 4 feet by 6 feet white poster board with a black marker (we also tried black tape, but the tiny change in surface height disturbed the robot's coaster wheel so we ended up using the drawn line). The path looked close to one one show above and featured curvatures in "both directions".  All teams needed their first attempt to calibrate their timing, but all teams managed to complete the challenge more or less successfully, eventually. Every robot used the standard left/right seesaw-motion algorithm, but in slightly different variations. At the end we placed two robots on the line for fun to chase each other and push the other off the track.

Team A: 100
Team B: 100
Team C: 100
Team D: 100
Team E: 100

Click here to watch the outcomes of this challenge

Sample Movies