WOOSTER, Ohio - Alejandro the Wind Bunny proudly demonstrated his newfound ability to sense variable air currents by maneuvering back and forth in front of two portable fans at a show-and-tell session Thursday morning in Taylor Hall. The carefully constructed device was one of three robots built by students in Susan Lehman's "Electronics for Scientists" class (Physics 220).
The assignment was to create a robot using a kit by Lego Mindstorms NXT, and equip it with a new sensor that could react to something in the environment. "The process is essentially a way to convert from analog to digital," explained Lehman. "It's a matter of teaching the computer to respond to a stimulus."
In Alejandro's case, the circulating air determines when he moves, how far he goes, and in what direction. The sensor, designed by junior Deanna Pickett and seniors Sul Ali and Mark Zimmerman, responds to light reflecting from alternating white and black strips at the bottom of a multi-colored pole with an anemometer, or wind gauge, at the top that catches the air current. "The more wind, the more movement," explained Zimmerman. "At a certain speed, the robot will turn sharply (130 degrees) in another direction."
The second robot, designed by junior Rob Daniels and sophomore Josh Cianca did not have a name, but it certainly had a "sense" of its mission. This device was constructed to respond to light. The robot reacts to the stimulus by moving toward the light, and then stops 10-12 inches short of the source. Daniels and Cianca had to scramble when a light-sensitive chip in the sensor they had built "blew out" the night before, but they were able to improvise and prepare the robot for its assigned task the following day.
The third robot also encountered a few setbacks, but designers Travis Brown and Mary Mills, a junior and senior, respectively, still learned a lot from their experience. The two tried to get their robot to detect the electromagnetic signal from a cell phone. The device would measure the strength of the signal and hone in on the source by keeping track of whether the signal became weaker or stronger as the robot moved in different directions. If the signal became weaker, the robot would pivot 135 degrees to get closer to the source. Unfortunately, the two young designers had difficulty calibrating the sensor to the cell phone signal because of its ultra-high frequency, but they now know what they need to do to enable the robot to sense the signal.
Despite the problems, Lehman was pleased by the work of her students. "They showed a lot of ingenuity and creativity," she said. "They learned a lot about what to do when they encounter a problem and how to work around it."