Page 57 - Robot Builder's Bonanza

26 ANATOMY OF A ROBOT

Figure 2-13 Sensors let your robot experience the world around it. Humans may perceive their
environment using eyesight and hearing, but most robots use simpler technologies like ultrasonic and
infrared distance measuring or light, sound, and touch. The sensors are integrated and processed by a
control circuit, which then performs some action based on the sensory input.

A SIXTH SENSE OF THINGS NEARBY

Humans use an elaborate system of sight, sound, and other senses to determine when some-
thing is close by. For robots, there are whole families of cheap sensors that do the same thing
and are very easy to implement.
One type uses ultrasound, just like a bat. The sensor emits a short ping— similar to the
sonar of a submarine— then waits for its echo. The time it takes between sending the ping and
getting the return echo tells the sensor how far away something is. Sounds complicated, but
the whole thing now comes prepackaged in a small device that costs less than $20.
Another scheme uses invisible infrared light and a bit of mathematics to measure distances.
The system is more fully explained in Chapter 43, “Proximity and Distance Sensing,” but suf-
fice it to say, these sensors are even smaller and less expensive than ultrasonic detectors.

TILT, MOTION, AND POSITION
Rounding out the sensory systems of today’s amateur robot are things like accelerometers for
detecting tilt and motion, gyroscopes for determining speed, and global positioning satellite

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