Tape Detection
To avoid driving off the edge of the playing field prematurely, we designed a tape sensor to alert the system to the perimeter of the inner playing field, which was outlined by low-reflectivity black tape.
Each tape sensor has three stages: the phototransistor, an inverting comparator with hysteresis to give a logical signal, and an LED to visually show the output signal.
Each tape sensor has three stages: the phototransistor, an inverting comparator with hysteresis to give a logical signal, and an LED to visually show the output signal.
For compactness we placed the four sensor circuits on one board and used one LM339 quad comparator.
Demonstration of LEDs indicating the surface under the sensor. By using these LEDs we didn't need to use a scope to test the output during mounting and debugging.
Though we used the sensor circuit during testing and development, we did not use it during the competition, as tests showed that we could reliably detect our opponent falling off the edge, and stop our attack so we did not follow off the edge after them.