60 SERVO 09.2017
Mechanical aspects of a robot can be as simple as two gear motors
driving two wheels with a swivel
caster wheel on some sort of base.
Or, it could be as complex as this
same robot, but with two multi-axis
arms, each with multi-axis claw
assemblies, and a pan and tilt sensor
array atop the structure. Add several
‘switch’ feelers and some sonar and
IR object / distance sensors, and you
have a loaded mobile robot platform.
The mechanics of a robot not only
involve the systems to create
movement, but the structure of the
I won’t delve into why you want
to build a robot or what the ultimate
use may be. Suffice it to say that you
just want to build a robot. By reading
this magazine, you already have the
interest. I will try to steer you away
from some of the more difficult robot
designs and configurations, just to get
you started in a great adventure.
I have met many people who
consider mechanics something akin to
working on a car or building a
machine of some sort. They envision a
mechanic as someone in dirty overalls
with a wrench in one hand and an oil
can in the other. Mechanics can
actually be any sort of effort to build
or improve a system that creates
Another definition describes
mechanics as “the branch of applied
mathematics dealing with motion and
forces producing motion,” but I don’t
see the in-depth hard math in laying
out a basic robot design.
A more in-depth definition
describes it as “the branch of physics
that deals with the action of forces on
bodies and with motion, comprised of
kinetics, statics, and kinematics.” I like
this definition better, so I’ll stop here
and just realize that all of you know
the differences between mechanics,
electrical systems, electronic systems,
and computers as applied to robots.
Building a Robot from
a Kit is a Good Start
Many people take the leap into
robotics by building a kit. The $150
Parallax ActivityBot (shown in Figure
1) is one of the best cost-effective learning kits
around. Other folks might
go the do-it-yourself route
of finding a box to use as
a chassis, adding a couple
of modified servos and
wheel assemblies, and
attaching a microcontroller
board such as an Arduino.
Either way is an
excellent path to follow to
get into robot building.
Where it might lead you is the
exciting part. So, let’s jump right into
the mechanics of building a robot.
The Next Step into
Unfortunately, some people have
stopped at the point of building a
simple kit or DIY version because they
are afraid of taking the next step(s)
into bigger and more functional
robots. So many people have
mentioned to me that they have no
mechanical skills and are convinced
they could never build the robot of
Keep in mind that just the act of
screwing the servos onto the
The Mechanics of Robot Building
In many of my articles, I always seem to mention the mechanical aspects of designing and
building a robot. This is not necessarily because it’s the part of robot building that I enjoy most
(which it is), but rather it’s the fact that the mechanics is what makes a robot a 'robot.' Were it
not for the parts that make a robot move, it would just be a 'computer.'
Figure 1. Parallax ActivityBot, fully loaded.
Figure 2. Karl Lunt's
TackleBot 3 made from
a fishing tackle box.