Page 250 - Robot Builder's Bonanza

Chapter 21

Choosing the Right Motor

otors are the muscles of robots. Attach a motor to a set of wheels, and your robot can
Mscoot around the floor. Attach a motor to a lever, and the shoulder joint for your robot
can move up and down. Attach a motor to a roller, and the head of your robot can turn back
and forth, scanning its environment. There are many kinds of motors; however, only a select
few are truly suitable for homebrew robotics. In this chapter, we’ll examine the various types
of motors and how they are used.

AC or DC Motor?

Direct current— DC— dominates robotics; it’s used as the main power source for operating the
onboard electronics, for opening and closing relays, and, yes, for running motors that propel
a robot across the floor. Figure 21- 1 shows a gallery of over a half dozen small DC motors
suitable for building small robots. They’re inexpensive, and they adapt easily to most any
robot design. You’ll learn how in this chapter and the ones that follow.
The alternative motor type, alternating current (AC), is seldom used in robotics. AC motors
are best suited for things like household fans and other applications where power comes from
a wall socket.

Not sure what AC and DC mean? Refer to the lessons in My First Robot, found on the RBB
FYI Online Support site (see Appendix A). There you’ll find a crash course in various electronics
subjects.

When looking for DC- suitable motors, be sure the ones you buy are reversible. Few robotic
applications call for motors that run in one direction only. DC motors are inherently bidirec-
tional, but some design limitations may prevent reversibility, so this is something you have to
be on the lookout for.
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