Build This Beginner
Bot (For Under $20)
We all have to start somewhere. For
robotics, the first taste usually comes
from putting together a basic starter
kit. You build it, run it, learn a few core
concepts, then put it on your shelf to
use as a bookend. Most starter kits
are single purpose, and don’t grow
with you.
Abetter approach is an expandable robot base that adapts while you learn. That’s the idea of the BeginnerBot —
specially designed for first-time robo builders. You start with
basic robot construction, including motors and wiring, and
you learn how robots move and steer. Using the same
hardware (that saves you time and money), you then
graduate to the next step, discovering electronic circuits and
control. From there, you learn about microcontrollers,
sensors, changing the behavior of your robot, and more.
The BeginnerBot is a low cost platform for exploring
robotics. As its name implies, the BeginnerBot is ideal for
beginners, and also students, teachers, and parents wanting
to involve their kids in the world of robots. I designed it to be
46 SERVO 08.2011
Part 1
by Gordon McComb
www.servomagazine.com/index.php?/magazine/
article/august2011_McComb
both inexpensive — the basic mechanical parts cost about $20
— and easy to make. You can construct the BeginnerBot in
just a few hours, with nothing more than ordinary tools —
things you already have in your garage. In this first
installment, you’ll learn how to build Phase 1 of the
BeginnerBot, using your choice of wood or plastic (or getting
the parts precut and predrilled, if that’s your choice). You’ll
also learn about the art and science of controlling the motion
of the robot — useful for things like chasing cats around the
house.
You will then take this knowledge and use it to
understand how autonomous robots are programmed to
navigate their environment. In upcoming installments, you’ll
learn how to use the same BeginnerBot hardware with
electronic control for feedback. From there, you’ll discover
how to add low cost microcontrollers for programmed
response; then how to remotely control your bot; how to add
inexpensive sensors to expand your robot’s view of the world;
and more.
Introducing the BeginnerBot
The BeginnerBot is shown in Figure 1. It measures six
inches across, and like many robots of its type, uses a pair of
motors and wheels for mobility. The two wheels are on
opposite sides of the robot base. These wheels can be
mounted center-line in the base, or offset to the front or
back. For the BeginnerBot, the wheels are mounted center-line. That provides a bit more flexibility.
The size of the wheels greatly influences the travel speed
of the robot. Larger wheels (for a given motor RPM) make
the robot go faster. The wheels on the BeginnerBot measure
about 2” in diameter. This means that for every revolution of
the wheels, the robot travels approximately 6. 3” ( 2 x pi, or 2
x 3. 14). With the motors specified, the BeginnerBot moves at
about one foot per second. A typical problem with
constructing wheeled robots is connecting the wheels to the
motors. The job is made easier when selecting wheels that
FIGURE 1. The BeginnerBot is an expandable, low cost
base for exploring the world of desktop robotics.