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CHAPTER 3

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Motion

“Every object in a state of uniform motion tends to remain in that state of motion unless
an external force is applied to it.”

— Newton’s First Law of Motion

3.0 Introduction

Making your robot move is a lot easier these days with the advent of Serial Servo Controllers
(SSC) and Electronic Speed Controllers (ESC). They all use the same mechanism to move, a
Pulse Width Modulation (PWM) designed to control the position of a servo.
A servo is a small motor that allows the position of its output gear to be precisely positioned by
a PWM signal. Figure 3-1 shows a picture of the standard servo, which is the main one I used
for differential drives, arms, and legged robots.

Figure 3-1. The Hitec HS-422 Standard Servo (Lynxmotion Inc.)

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