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Bots /The Ultimate Palm Robot/ Mukhar & Johnson / 222880-6 / Chapter 2

Chapter 2 Getting the Parts 33

Enough theory. Need to get your hands on some sensors? Some of the
online retailers that we found carrying Sharp sensors include

❏ www.digikey.com/DigiHome.html
❏ www.arrow.com
❏ www.nuhorizons.com

Motor City Madhouse
As we’ve already mentioned, the servos are the motors that drive the wheels
based on a set of commands sent by the controller. Usually, servos are built so
that they rotate some set amount and then stop. This makes them well suited
to moving robotic appendages that have a limited range of motion, but it
makes them unsuitable for driving the wheels of a robot that need to be able to
rotate continuously in one direction. To deal with this problem, you can mod-
ify a normal servo so that it can rotate continuously.
On the other hand, you can let someone else do the modification for you,
and buy the servo from them (like the ones in Figure 2-6).

Figure 2-6
Here, you can
see the servos
that come
with the
BrainStem
kit. These
servos have
already been
modified so
that they
will rotate
continuously.

Your best source for the servos is Acroname. Another excellent source: Mr.
Robot (www.mrrobot.com). Both Acroname and Mr. Robot also have direc-
tions for modifying servos for continuous rotation.

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Monday, May 12, 2003 10:17:24 AM