Sensors

	Bumper & limit switches	Turn on when you bump into something (basically it's a button)
	Infra Red	Sort of a proximity detector. You send out 38-40khz through a IR led, and then detect with a IR module. Gives you qualitative info like something is there or not, but not a good indicator of distance. Won't see black objects, though.
	Sonar	Something like the Polaroid 6500 sonar device can detect objects from 6" to 35' away. It outputs 40-60khz sound bursts and calculates the time of flight to get the echo. Gives you quantitative info as in the number of inches something is away. Some things don't bounce sonar well, so it won't see everything.
	Motion Detector	Detects changes in ambient light. So if your cat walks by, it'll give you a signal. Your robot has to remain still during the detection process.
	CdS	Cadmium Sulfide sensor used to detect light. It is basically a resistor that gives changes in the amount of light that falls on it's detector. They're slow to react, but work great.
	Laser Rangefinder	These are expensive, but are very accurate.
	Image processing	Use a video camera to get an image, and process image with a PC. There are many techniques to process the image.

Last Updated on 31, January 1998