Designing and Building a
Part 2
ROBOT from
SCRATCH
In Part 1, we went over
the first part of the
design phase. Starting
with “I want to build a robot”
we came up with a goal for
the robot, and a specific
set of criteria we wanted it
to meet. Next, we brain-
stormed many different
ideas, compared them
analytically, and chose the
one that was best. We
decided upon a horizontal
bar spinner much like an
upside-down lawn mower.
With that done, we can now
begin the actual design! In
this installment, I will be
discussing how to determine
what you need for parts,
how to choose them,
developing your design,
and more!
by Brian Benson
There is one thing that is true about design ... it is an
iterative process! While I have outlined the following steps
in the order that is the best way to approach a design, you
will find that you will spend much of the time going back
and forth making adjustments, changing your mind, and
fixing problems.
Different Types of Frames
The first step in designing your robot is deciding upon
a frame type and layout. A frame is what holds the entire
robot together and there are many different types of
frames. These include the base plate frame, welded stick
frame, unibody, and milled frame. Each of these has their
own unique attributes that make them better or worse for
different situations.
Choosing a frame type early is important because
it will influence what types of components you choose
to use and how you will lay them out. For example,
wheel chair motors will easily work in a welded stick
frame, but will be more difficult to implement in a base
plate frame.
36 SERVO 04.2008
Base Plate Frame
The base plate frame can be the
easiest and most simple frame to build
and it is best suited towards simpler
robots. In these frames, the main
tructure is simply a thick flat sheet of
metal or plastic that all the components mount to. This
s a very popular frame type for beginners and those
without many tools. In most cases, it requires just a saw
and drill. However, for more complicated robots —
especially ones that require high strength at low weight —
this type isn’t ideal.
Welded Stick Frame
The welded stick frame is often
made out of extruded metal such as
tubing, angle, or u-channel which is
welded together to form a type of
stick frame. All of the components
then bolt onto the frame. A good example of a completed
bot with this type of frame can be seen in Figure 1. The
benefits of this frame are that it’s easier to manufacture
