In an attempt give our robots as much information about their surroundings as possible, we designed bumpers with two touch sensors so the robots would know: a) if a front or back bumper had been hit, but also b) on which side a bumper had been hit. However, due to the limited number of sensor inputs on the RCX brick, we could not fit in all four inputs from the different touch sensors. We fixed this problem by building a simple parallel resistor circuit. Using four switches and four resistors with selected values, we were able to get a different return value depending upon which switch—or combination of switches—was tripped. This allowed us to use only one sensor input on the RCX while gaining a considerable amount of sensory information.
