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Chapter 19

Robot Power Systems

ou learned about batteries in the preceding chapter. Now you can go about using them
Yin your robot designs. That takes attaching the battery (or battery pack) to the robot and
stringing wires from the battery to the motors and electronics of your robot.
Easily enough said, but the specifics are a bit more than this. This chapter cracks what you
need to know to apply power systems to your robots.

This chapter makes reference to common electronic components, such as resistors, capacitors,
and diodes. If you’re new to these subjects, be sure to check out Chapter 30, “Building Robot
FYI Electronics— the Basics,” and Chapter 31, “Common Electronic Components for Robotics.” You
may also want to check out the newbie lessons in My First Robot, located on the RBB Online
Support site. See Appendix A.

Power and Battery Circuit Symbols

Let’s start with the symbols used in electronic circuit designs to denote power and battery
sources. Schematics are the road maps of electronic circuits. And in most circuits, it all starts
with the power connection. For robotics, that power typically comes from batteries. Figure
19- 1 shows the most commonly used symbols for power and batteries.

• When power comes from an arbitrary source (batteries, connection from wall transformer,
whatever), it’s often shown as a small circle, or sometimes an upward- pointing arrow. To
complement the power connection, the circuit will also show another connection for
ground. The exact form of the ground symbol is varied, but the set of three lines tapering
to a point is among the most common.
• When power comes from a battery or battery pack, the symbol indicates the positive con-
nection with a + (plus) sign. The (negative) connection is inferred.
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