Page 96 - Build Your Own Combat Robot

Chapter 4:
Motor Selection and Performance
the robot. If the engine is used to drive a hydraulic pump, the pump needs to have a 77
solenoid valve to reverse the direction of the hydraulic fluid. Probably the most
common use for gasoline engines is to power spinning weapons because these
weapons spin in only one direction.
For more information on how to use an internal combustion engine in a combat
robot, talk with other robot builders that have used them and read up on how to
use large engines in model aircraft.

C onclusion

The motors are the muscles of your robot. By understanding how the motors work
and how to push them to their limits, you will be able to determine the appropriate
motors, the types of batteries, and the appropriate-sized electronic speed control-
lers for your robot. When building your combat robot, the motors are usually the
first major component that is selected. Sometimes the motors are selected based
on performance goals, and other times the robots are built around a set of motors
thatyoualreadyhave.Bothareacceptablewaystobuildcompetitivecombatrobots.
Understanding how current works in the motors will help you determine what
type of battery you will need. Chapter 5 will cover how to determine the appropriate
size of battery you will need for a robot. Understanding how fast a motor turns
and how much torque the motors can generate will help you determine what type
of speed reduction/transmission the robot will need to meet your desired goals.
Chapter 6 covers this topic. By understanding how the voltage and current relate
to one another, determining the right type of speed controller can be accom-
plished. Chapter 7 will discuss how to select the appropriate-sized electronic
speed controller. Understanding how heat can destroy the motors will help you
avoid accidental meltdowns.
Before selecting a motor, you should understand how the subjects presented in
Chapters 3 through 7 relate to one another. Now, this isn’t required—in fact,
many robot builders simply pick a motor and build a robot around it. If they’re
lucky, everything works out just fine. However, most robot builders learn the
hard way, as things break because they inadvertently pushed components past
their capabilities. How you choose to build your robot is totally up to you.