Lab 3: Braitenberg Vehicles

"This is an exercise in science, or science fiction, if you like that better. Not for amusement: science fiction in the service of science. Or just science, if you agree that fiction is a part of it, always was, and always will be as long as our brains are only miniscule fragments of the universe, much too small to hold all the facts of the world but not too idle to speculate about them."

-Valentino Braitenberg

Lead TAs: Somchaya Liemhetcharat, Si Yang Ng

Lab Schedule for Tuesday, 6th February 2007

Be sure to arrive at least 15 minutes before your demo time.


This first robotic lab is intended to provide an introduction to your lab kits. The hope is that this task will be easy enough to serve as a good starting point, yet challenging enough to expose some of the common problems encountered in robotics.

In his book, Vehicles, Braitenberg suggests that machines (robotic or biological) can exhibit increasingly complicated behaviors as a result of neural connections between sensory organs and actuators. He goes on to discuss how these behaviors may be implemented using light sensors, and motors. (see illustration) We thought this would be a good theme for the first Lego lab assignment.


P. J. McKerrow, Introduction to Robotics, pp 1-49.


Programming, digital and analog input/output control.

Challenge Statement:

Build a robot (creature) that chases light. See powerpoint presentation for more information.


Successful completion of this challenge will require your robot to "home in" on a light source to reach a goal area. The goal area is defined as the set of all points in the working plane within 6" of the light source. The robot's initial position and orientation with respect to the source will be unknown, but will not be greater than 24" away, and the initial heading will diverge no greater than 45 degrees from the optimal path to the source. (see diagram) The task will be considered achieved when any part of the robot crosses into the goal area and stops there (you will have the option to switch off the light source). In other words, the robot only needs to be touching the goal area (as opposed to contained in), but must be able to stop there.

Construction Tips and Things to Think About:

  • Connecting the photo cell
  • Matching photo sensors
  • Analog to digital conversion
  • Methods for interpreting analog inputs
Tips from Chau
Demo Times
Grading sheet   
Acknowledgments: picture and quotation from:
Braitenberg, V. 1984. Vehicles, Experiments in Synthetic Psychology
London, Cambridge: The MIT Press