CHAPTER 5
■ Chapter 5: Numbers and Units
Here is the last building block before you’re introduced to the line-following robot. This chapter describes
the numbering systems and abbreviations common in robotics. It’s important to get at least a basic sense for
these things, although you can always turn back to this chapter later if you run across something you don’t
understand.
Choosing the Metric System
Scientists use the metric system because it is well defined in universally constant ways and easily converts by
multiplying and dividing by ten. As a robot scientist, you should use the metric system for your own work. This
also permits you to be snobby towards those Neanderthals who still use the old-fashioned Imperial system.
This book uses the metric system except where a manufacturer specifically designs or specifies a part in
a non-metric measurement. For example, if the manufacturer makes a board with holes spaced 0.1 inches
apart, then that is how it is described. Although inches could easily be converted to metric, 2.54 millimeters
isn’t really the official specification for that board.
Another example: If a contest limits robots to 8½ by 11 inches, it’s preferable to continue to communicate
in those terms, as people in the United States readily understand that’s the size of an ordinary piece of paper.
The same audience doesn’t immediately recognize those dimensions in metric, 21.59 by 27.94 centimeters.
In addition, some numeric precision can be lost in the conversion between inches and centimeters.
Reducing Powers of a Thousand
Long numbers are difficult to read (see Figure 5-1). If a circuit calls for a component of the value 10000000,
the reader may accidentally install something significantly higher or lower by merely miscounting the
number of zeros.