Servo - March 2008

Designing and Building a

ROBOT from

SCRATCH

by Brian Benson

Designing and

building a

custom robot

for the first time can be

a very daunting task.

Robots consist of many

subsystems, all of which

must work seamlessly

in order for the robot to

function properly. The

challenge in designing

and building a robot

is not only in fully

understanding these

subsystems and making

them work together, but

doing it in a way that has

never been done before.

When you are creating a custom robot, there is no manual,

instructions, or tech support. You start with a blank slate, with thousands of options available to you. You have to ask yourself and answer questions like “How big will it be? What will power it? What materials will I use for the frame?” and many more. With an unstructured approach, this can seem like an impossible task. However, if you approach the problem with a plan, breaking down the problem into chunks, it is not as difficult as it seems!

In this series of articles, I will be discussing how to go through the entire process of designing and building a custom robot. I’ll show you how to break the process down into manageable chunks and see to it that the idea in your head turns into a reality.

damage. Notice that I didn’t specify how I wanted to cause large amounts of damage; there should be no “how” in a problem statement — only a “what or why.”

The most common example of a good problem statement is for mowing the lawn. “We need a better product to mow the lawn” is flawed, because it limits you to only ways to mow the lawn. However, “We need a new, innovate way to keep lawns looking good” opens up a completely new set of possibilities. A good goal statement will help to direct your design from start to finish.

Design Specifications

Identify the Goal

Every engineering challenge begins with a goal or problem statement that clearly and concisely lays out what you want to achieve. It should describe what the purpose and strategy of the robot is. It should not, however, limit or direct what the final design will be.

My background is in combat robotics, so I will be discussing the design process for that type of robot. As an example, I have decided I want to build a competitive, offensive based robot that has the capability to knock out other robots by causing large amounts of

After identifying qualitatively what I want the robot to do, I need to decide on a set of design specifications. This is a list of criteria that describes the robot quantitatively and will begin to answer questions like “How many wheels? What is the maximum weight? How fast will it move?” It needs to be as specific as possible to make the design process easier later on.

The best type of specifications are ones that can be measured, so that throughout the design process you can evaluate how well your design is meeting your goal. For my planned robot, the design specifications are as follows: