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FIGURE 7-2 An elderly robot toy ENERGY CONTROL AND SOFTWARE 167

windings and keep the efficiency up. Semiconductor companies sell chips specifically
designed to control motors in an efficient manner. Some low-voltage motors are avail-
able, but it would restrict our choices. Many motors are available that require a 12-volt
drive. Fewer are available that will work with a 5-volt drive. The requirement to turn the
voltage off and on to a motor further complicates the supply question because most volt-
age switches (and wiring) will also drop the voltage available to the motor.
Several alternatives also exist to traditional motor technology. Esoteric motors may
be fun to investigate, but use them with care. The motor found at www.drives.co.uk/
news/prodnews/news_prodnews148.htm, for example, uses piezoelectric power to
create movement and uses low voltage.

Control Systems Most computers are designed to work from power supplies in the
3- to 5-volt range. We’ve discussed processor technology before, including power sup-
ply requirements, but one aspect of the computer technology we did not touch on is rel-
evant to battery-powered robots in particular. Control system circuitry made from
Complementary Metal Oxide Semiconductor (CMOS) technology has certain advan-
tages in this application. CMOS semiconductor technology, aside from being a