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So You Want to Build a Robot

by Steve Kaehler Fall 2006



This article is based somewhat loosely upon a presentation given at the regular February 2006 monthly meeting of the Seattle Robotics Society. The presentation slides can be found on the SeattleRobotics Yahoo Group in the “Files” area. You can access it by joining the group ( The presentation upon which this article is based and the article itself are intended to get your creative juices stirring and so won’t present a lot of detailed technical data. However, they will present a way to navigate through the overwhelming amount of information available and try to provide a method for determining what makes sense for you.


I won’t pretend to be an expert on any of the subjects presented here so please don’t make that assumption about me. In fact, I know relatively little compared to the vast storehouse of knowledge in the heads of so many other SRS members, but I’ve learned a great deal just from being around so many creative and talented people, asking questions, and seeing what they’ve done, etc. I hope you will be inspired by this article not only to build something, but to share what you’ve learned with the rest of us. Together, we can help each other learn more, start, improve upon, or even finish our own projects. I hope you will see gaps in this presentation that you can fill with your own sometime. I would enjoy having SRS members regularly presenting on topics they understand and want to share about. I will touch on many things briefly and lightly. Each could and should be its own presentation. I hope you all will help make this happen.

The following questions served as the outline of the presentation.

Why do I want to do this?
Where do I begin?
What should it look like?
How big (or small) should it be?
What should it do?
Will it move or be stationary?
Will it have a “brain”?
What must it be able to sense?
What is possible for me today?

Neither the presentation nor this article is a sales pitch for any particular products or methods, so consider the product information in light of your abilities, goals, and finances.

So We Begin…

People outside the SRS really don’t understand the challenges of building autonomous machines. They don’t realize that how well we humans can adapt to environments, situations, and problems is one inspiration for trying to emulate this in the machines we attempt to make. Our robots typically cannot simply be turned loose in the great wide world. They are vulnerable, have limited ability to learn and adapt, and must be fed regularly. They are rather like human infants, often requiring as much attention and protection. But this doesn’t stop us from trying, dreaming, scheming, experimenting, learning, and growing in this ambitious hobby. Let’s start with the first question.

Why do I want to do this?

Many people get into this hobby as an educational experience. This is a great reason because you will learn a lot. You’ll learn about electronics, mechanics, programming, construction techniques, materials properties, artificial intelligence, logic algorithms, and a ton of other things. You will probably learn more about what you don’t know than what you do know because many disciplines come together in a robot and the more you learn, the less you’ll realize that you know. So as an educational exercise, robotics is hard to beat.

Some people want a hobby that’s fun and enjoyable. Building a robot certainly offers this and is a creative outlet for people looking for that “really interesting” technical challenge. I won’t lie to you though. Building a robot isn’t easy, but it is very rewarding and gives you a great sense of accomplishment.

Maybe you have tons of money and nothing to do with it. I wish I had this problem, but I’m not Bill Gates or Paul Allen. I can promise you that your robot will consume as much money as you feed it, so bear this in mind as you embark down the various possible paths I’ll be outlining.

Some people are competitive and build robots for contests, maybe hoping to win some money or prizes. This is a fun, sometimes grueling path, but a worthwhile effort. Perhaps the incentive of an attractive prize will provide the motivation you need. Maybe you have talked about doing this but have never quite gotten that final push, but then someone challenges you to do it. Or maybe we’re all just a little crazy….Whatever your reasons, you’ve taken the first step on an interesting journey, now let’s look at some other steps.

Sony AIBO Robotic Dogs
Evolution Robotics Robot

Where do I begin?

You have found one of the best resources in the world for building robots by connecting with the Seattle Robotics Society. Next year will be the 25th anniversary of the SRS’s existence. Our website ( is a treasure trove of information. You’ve made an important first step just by attending a meeting (apologies to those not local to Seattle). Come regularly, contribute to the collective knowledge, present on things you know about so we can all learn, ask about what puzzles you. The monthly meetings offer you a chance to meet like-minded people face-to-face, share your successes and struggles, learn about new technologies, and enjoy the comradery of a very unique group of people. Contribute to the collective experience at our meetings and events like the annual Robothon ( & other events. Participate in our annual Robothon contests and events. Help a F.I.R.S.T. ( team (or two). Mentor young men and women in technical areas so there will be up and coming engineers and scientists to tackle the challenges yet to come. Participate in teaching the next generation about technologies you know. Talk to people; Ask questions; don’t be shy; join the World-wide listserver (; participate in the weekly chats; write articles for the online SRS Encoder magazine. Participate on the listserver and contribute to the vast store of information in the email archive on countless robot topics. There are many ways for you to connect.

So, where do I really begin?

Okay, you’ve decided that really want to do this thing, now what? There are many COTS (commercial off-the-shelf) solutions if you want to get going now, but you’ll still have to do some programming because chances are, these machines won’t do exactly what you want or everything you’d like. There are options where a lot of engineering is already done for you. You might pull something out of a box, turn it on, and set it free to wander around like the robot floor sweepers. You can also piece things together like building blocks (from a kit), attach a laptop computer to a mobile platform, load it with batteries, place it on the floor, and ignore it.


Roomba Robot Vacuum

Scooba Robot Wet
Floor Cleaner
Lynxmotion Walker

Or you can just build a do-it-yourself kit. Some examples of these types of platforms are shown in the pictures below. There are pre-built robots, building block robots, LEGO brick robots,
“Erector set”-like robots, household appliance robots, and kit robots. The choices are virtually unlimited.

• Sony AIBO
• LEGO Mindstorm (brick-to-brick)
• Evolution Robotics (laptop controlled)
• Roomba (self-guided but dumb)
• Lynxmotion, Parallax, RobotStore
• Kits (e.g. Hobby Engineering)

You can also:

• Copy others
• Build something from scratch
• “Kit-bash” an RC model or other kit
• “Kit-bash” something never intended for robotics
• Use F.I.R.S.T. robot parts
• Use VEX Robotics parts
• Build an SRS Workshop Robot

If you want to build what someone else has made by copying their design, you may be able take advantage of the trail they’ve blazed and possibly avoid some of the pain they’ve endured. You might duplicate something that someone else has done, obtaining the same platform and equipment and then repeating their fabrication process. They’ve worked through many of the challenges and difficulties and want encourage others to follow behind them by posting their accomplishments on the web in sufficient detail for others to copy. The SRS strongly supports this type sharing and collaboration (especially through Encoder articles) because everyone benefits and hobby robotics gets better and more accessible to more people. Of course, if someone wants you to by their kit, they won’t give too many details away.

You might decide to build something from scratch, buying or obtaining bits and pieces from various sources and putting them together into what you hope will be a functional system.

Jim Wright's Fire Fighter Robot
Gary Teachout’s LC
Ted Griebling’s Macbeth

This is a very ambitious path, but one that can be done with sufficient time, resources, and
persistence. Some SRS members have very creatively turned unlikely items in to robots. Karl Lunt turned a fishing tacklebox into a rather nice little robot with a camera and a built-in carrying case for its own spare parts. Gary Teachout used a plastic bucket as the base for a fire- fighting robot, and I can only guess what Ted Griebling’s “Macbeth” was made from.

Turn a “dumb” remote control toy vehicle into an autonomous robot to take advantage of the existing mechanical and electrical systems. Kit-bashing an RC model into a robot saves you some mechanical and electrical engineering, but has its challenges too. The term “kit-bashing” comes from the days of model train and hot-rod model building. It means combining pieces from a number of kits into a new model, often by literally fusing the old parts into new ones. Building a robot this way might evolve something like an RC truck or two into a single machine with pieces of each, then “modifications” are made until you can mount a robotic arm, remove the RC electronics, and install a microcontroller. The robot may resemble its component parts, but will probably look more like a refugee from the “Borg Collective” than whatever it originally was.

The parts used by F.I.R.S.T. teams can be purchased and used to build larger robots. During contest build ups, actual F.I.R.S.T. teams will have priority on ordering these parts, but sometimes, after the contests are done, these robots are stripped apart and sold off so used pieces can be obtained. Radio Shack ( ventured into the kit robot construction business by offering VEX Robotic ( parts and kits. These are essentially building blocks that you can use to piece together small to medium sized robots.

There are also “basic kit robots” available that walk you through some of the stages of robot development (mechanical, electrical, and programming) via handbooks and guides. For example, consider the BOE-BOT made by Parallax (

What should it look like?

Contest robots tend to be designed and built within specific limitations in size and weight, must obey certain rules, and are required to perform specific tasks or functions. They are also usually built under a lot more time pressure than “general purpose” whatever robots. For example, these robots might compete in contests like robot sumo, line following, Robo-magellan, maze-solving, robot combat, etc.

These robots tend to have a practical, functional appearance partly because cosmetics aren’t important and partly because time is usually short and “good looks” are the last consideration. Of course we robogeeks prefer seeing all the entrails rather than hiding this kind of cool stuff “under the hood”.

Suppose you want a robot that looks like R2D2, or C3PO, or the Sony AIBO dogs or Ryan Wistort’s “Rybot” (5-legged spider-like walker, These robots have a “polished” appearance. They are pretty to look at and the “guts” that make them go is hidden from the casual observer.

Your robot might be made purely functional, built to do specific things without regarding aesthetic pleasantries. This has a certain high-tech “coolness” with lots of wires, mechanisms, lights, gadgets. You might want a robot that models a natural creature (a person, insect, animal, or fish). Some examples are the Honda “ASIMO” or Robo-raptor, Robo-dog, and robotic fish. Or it might simply have a well defined function and purpose like the industrial factory robots used in manufacturing plants. These robots have limited functionality outside of their main purpose and usually perform repetitive tasks with great precision and quality. Some people want an electronic “pet” that follows them around the house, perhaps fetching beer or a snack from the fridge. Maybe it keeps track of the TV remote or better yet, sets TV by verbal command. There are also practical applications where a simple but robust machine is needed to do something risky or dangerous like defusing a bomb.

Robotic creatures:
Functional (manufacturing):

How big (or small) should it be?

The “Colossus” computer from the early 1960’s movie, The Forbin Project, was depicted as a gigantic machine embedded deep in a mountain. It was given control of all the US nuclear weapons because it was thought that a totally logical and objective machine would not react emotionally and accidentally blow up the planet. Shortly after it was activated, it discovered another similarly-tasked machine (“Guardian”) to which it linked. Together, they eventually took over the world by compelling the designers to construct “eyes” and “ears” so that they could interact (read: blackmail) the world’s inhabitants to do their bidding.

LynxMotion Walker
Herbie the Solarbotics Light Chaser

Few people have aspirations to build such gigantic machines and no one wants to become their slave, but a fixed robot that interacts remotely with its environment through drones has certain advantages and can have very sophisticated capabilities. For example, fixed robots aren’t limited in size, have ready access to unlimited power, and can now reach as far as the Internet will permit which is literally anywhere in the world thanks to technologies like Connexion by Boeing Using X10 technology ( you can literally make your home into a robot of sorts and you won’t have to worry about your portable power sources (batteries) running down. Since this technology allows control of practically any electrical or electronic device in your home, your can build a “smart” house that sense its occupants and responds to them.

The size of a robot is sometimes driven by external functional requirements such as what does or where it must be able to go.

"Johnny1" Walker
DARPA Grand Challenger

One SRS member, Ted Griebling, built a wonderful little “M&M” sorting robot called “M+M’bot” (see photo below) that was really small, battery-powered, and could capture and sort M&Ms and Skittles by color. It was a wonder to watch considering how small it was and how well it worked. He fabricated everything himself and put it together into a package that must have required working through a magnifying glass at times. There are also Micro-sumos and robot soccer robots that fit in 1” cube (see photo below). The robots pictured below range from an inch cube to a Hummer. Then there are those in the middle, probably more
in the feasible arena for average hobby robot builders like Sumos (10-20 or more centimeters, a few pounds), Robo-Magellan robots which are 2-3 ft square and weigh perhaps fifty pounds, maze-solvers and line-followers that might be a little smaller.

M & M Robot
Tackle Box Robot

At the other end of the spectrum you have large, heavy one like F.I.R.S.T. robots that can be a dozen feet tall and weight several hundred pounds. This category also covers the industrial robots used in factors for manufacturing operations and vehicular robots (Hummer-sized) such as the ones built for the DARPA Grand Challenge.

What should it do?

When deciding to build a robot, the answer to this rather important question will really help set the robot’s evolution on the path to success. It is possible to build something with no particular purpose in mind, but finishing such an undefined creation may prove difficult. Robots sometime evolve from one purpose to another, perhaps start life as a maze-solver, then maybe a fire-fighter, then a sumo, then who knows. If it is designed for some sort of competition in mind, there will be constraints and rules that must be obeyed and this usually creates a machine with pretty specific functionality and capability. However, if you simply wish to create a sort of electronic “pet” for companionship, then what it does might not be quite so important as long as it moves. It might behave like a pet that follows you around the house, fetches beers from the fridge, keeps track of the TV remote, or maybe sets the TV by vocal command. Maybe one day it decides that it should control your TV rather than you and convinces you that it knows better. As time passes, such a robot may “grow” new features and functions as you have time and inclination.

Some people are just looking for an interesting technical challenge when it comes to building something. Building a robot capable of doing a particular job will fit this bill to a “T”. There are few things as tough as designing and building something for a specific problem or task.

Then there’s people who need a hobby expression, like me but aren’t really as concerned about what the robot does as that it “seems alive”. Robotics provides a way to be extremely creative yet sometimes practical all wrapped up in single package.

How about building a security sentry capable of monitoring your home or business, perhaps collecting data or packages, or mapping and exploring. Such a robot might be a tour guide in a museum or simply a source of amusement to visitors that demonstrates technological possibilities. The options are a broad and unlimited as your imagination.

Will it have a “brain”?

So let’s say you’ve chosen a general form, size, and function. How smart does it have to be to accomplish this? Really simple robots don’t even need brains. They can copy insects that simply react and respond to external stimulus. You select some environmental effects that the robot can sense or measure and then teach it to respond to them. You can do this with some simple digital logic the way B.E.A.M. robots ( do if the measurement and response are related simply enough.

ARC (Advanced Robot Controller)
68HC11 "BotBoard"

If more sophisticated response is required, some type of microcontroller with its associated programming will probably be necessary. In fact, more that one may be needed to do everything you want. You might mix low and high power processors into a distributed architecture that relegates the primitive functions (motor control, basic sensor processing, etc.) to simpler, lower power controllers while doing the higher decision functions with something more like a portable PC or workstation. Some vision system now have processing capability built in that delivers target data within the camera’s field of view as a data stream freeing the primary controller to do other things ( This sort of decision will certainly introduce the added complexity that comes with software design and implementation. Microcontrollers are getting more and more sophisticated and less and less expensive but nothing yet completely replaces the arduous task of designing and writing working code. Even systems that give you a very high level interface where graphical screen elements are virtually “wired together” on screen still requires some thought about what the robot should do and how. The controllers shown below are great possibilities for smaller robots and can be ganged or networked together for more complex control schemes and architectures.

What must it be able to sense?

One of the challenges that come with trying to build a machine capable of interacting with the world is giving it sufficient sensory input. We humans have a huge amount of incoming data fed to us by our eyes, ears, nose, mouth, skin, body, and brain. Our brains can process and filter this vast information stream down to a level that keeps us sane, yet can do this in real time. Just try building a robot that can handle video, audio, olfactory, position, motion, thermal, optical, etc. and decide quickly and on-the-fly what to do about it.

Evolution Robotics PC Robot
"Gumstick" PC

A most daunting task indeed, but one that adds to the challenge and intrigue of this extraordinary experience we call “building robots”. It is possible to obtain sensors that can measure almost anything, giving a robot far greater sensory capability that we possess, but the real problem isn’t the sensing. The real problem is processing those sensors into manageable data streams and then figuring out what to do with it all. This has challenged robot builders from the beginning. The contestants in the DARPA Grand Challenge ( faced first hand just such a task in sensor fusion as they constructed vehicles with the seemingly simple task of driving across the desert from Point A to Point B while avoiding obstacles that would stop them. First time this was attempted (March 2004) none went more than ten miles while this last year (October 2005), a number of vehicles not only made the journey, but did it within the prescribed time limit. This showed an extraordinary leap in technological capability, but this was most likely partially due to the information collaboration required after the contest the first time. Designers were able to see in detail how their fellow contestants tried to solve problems, what worked and what did not. They also recognized that as significant as their accomplishments were, fully autonomous vehicles have a long way to go before being ready for unsupervised release into the world. The sharing of information and experience is one of the important things that the SRS strives for in our robot building experiences. When the DARPA contest was completed the last time, much of the success was based on what was learned previously not only by trial and error but by this collaboration.

Mars Rover
Combat Robots "at play"

What is possible for me today?

So you now have some suggestions, ideas, and research paths that should help you along on this adventure. Where will all this lead? That’s really up to you, but wherever building a robot takes you, share the ride with others so both you and they can learn and grow through the experience. Will it be cheap? Probably not, but you don’t have to bankrupt yourself either. Try to look at the “big picture” recognizing what you are really trying to accomplish. If learning is your primary goal, then you will probably get a good return regardless of how successful your robot actually is. Will it be easy? Unfortunately, no, but it isn’t as difficult as it used to be and there’s a lot more help and resources available than five or ten years ago so take heart, you don’t have to go through it alone. The future holds many intriguing and exciting possibilities as more and better systems, kits, and tools become available. We have seen huge changes happen already and I don’t doubt that even bigger and better changes are yet to come.

I wish to extend a heartfelt thank you to all the trailblazers that have knocked down so many obstacles along this path. I have taken the liberty of borrowing pictures of their creations from their websites, past SRS Encoder articles and meeting notes to show you what is possible. I hope they inspire you like they’ve inspired me.

Happy robot building.