Robot Construction Tips and
Frequently Asked Questions

by Jim Smentowski ©2003

Hometips page last updated 5/7/03

General Robot Questions

- What is Robot Combat?
- People do this for FUN?
- Are there Prizes?
- What sort of people do this?
- When and where are competitions?
- Isn't this expensive?
- I'm only a kid-what else can I do?
- What costs the most?
- What Speed Controller options are there?
- How can I get a sponsor?
- How long does it take to build a robot?
- Where do I begin?
- What design should I use?
- Do I need a prototype?
- What tools do I need?
- Can't I just modify an RC car?

General Robot Questions (continued)

- Can I buy parts from you?
Where do I get my parts?
- How big can my robot be?
- What weapons can my robot use?
- What does the robot run on?
- What do I make the armor out of?
- What do I use to control my robot?
- What do I use to move my robot?
- How does the signal get to my robot?
- How do I steer the robot?
- Should I take pictures?
- Can I come see your bots?
- What's up with Robot Wars?
- What's up with BattleBots?
- Do you make the best robots?
- Where can I get more tips?

BattleBots Specific Questions

- What's up with the 'golden nut'?
- How does the show I see on TV work?
- How does the match scoring work?
- When is the next BattleBots?
- How did you do at BattleBots?

We highly recommend you also read Judge Dave's guide to winning

What the heck is this Robot Combat stuff all about?

Well, it's like this...Its a sport thats been around for many years, I'm not exactly sure about the first time someone put one robot up against another, but its been going on for a couple of decades at least. Most recently, this sport has gained a lot of public attention and support as organized annual competitions put mechanical radio controlled beasts of steel and aluminum into a battle-to-the-death match of skill, engineering and coordination.

We've been through a lot in the last several years in this sport, make sure you read my History Page to catch up.

Robots involved in robot combat usually weigh from 2 to 488 lbs, and similar events even put 2 ton machines into similar situations. The more popular events such as BattleBots and Robot Wars have regulated weight and weaponry rules to conform to audience safety. Its a chance for these people to show off what they can design and build directly from their imagination.

As one well-known and successful competitor, Mark Setrakian, puts it, its a great opportunity for "people who like to kick butts with their brains".

You've got to be kidding, people actually do this for FUN?

Oh yes. But remember it is a lot more that just a bunch of guys wanting to see stuff smashed up and get destroyed. Its a chance to see that something that YOU designed, that YOU built, that YOU controlled, WIN! But as with anything, winning is definitely not everything. Words cannot describe the feeling you get when you've finished building a robot and take it for its first test drive. What a great sense of satisfaction and fulfillment! At least for me, that is the key to this whole thing.

Another fantastic part about this sport is the people. A huge vault of knowlege is out there in the robot combat community. And usually you will find that many of these people are more than eager to help you out with your questions and problems.

Are there Prizes at these competitions? Is it really worth it?

Well, recently, there have been up to $6000 paid to the winner of some competitions, but there are new events surfacing all the time- an international robot sumo group has very handsome cash prizes and rumor has it that other future events will pay off even better. It is a growing sport and the stakes will only go up.

But, as for your second question of 'is it worth it'... Indeed it is for me. Although the cash is a nice incentive, it is not the reason we do this. Ask any robot competitor, 95% of them will tell you that prizes do not matter, its the satisfaction you get after building a successful robot.

What sort of people actually do this stuff?

All sorts of people with different backgrounds, not just your stereotypical engineering geek will build a combat robot. Engineers, students, artists, lawyers, writers, designers, you name it- they have all built robots for combat. Age range is rather broad too, I've seen 11 year olds build a competition-worthy 'bot! And the variety is growing all the time. You don't need any special education for this, that's what's so great!

When and where are these robot competitions?

Well, the first BattleBots was in August, 1999 in Long Beach California, and there have been several events since then, averaging about 2 per year. Stay tuned to the BattleBots and sites to stay current on when the next events will be.

There are currently many other smaller events happening around the country, and even around the world. I try to keep up to date as much as possible on my Events page.

Isn't this kind of expensive?

Nope. It's really expensive. Well, most of the time.

I usually have to be careful when I talk about this, because it IS possible to build a competition-quality combat robot with less money. However, there are certain components of the robot that are very difficult to try to build yourself, and all the usual and most commonly used aftermarket alternatives can be quite costly.

It really depends on how detailed you want your design, what kind and quality parts you use, and the tools you use, there are countless other factors as well, far too many to mention. Also, typically the larger weight class of the robot, the stronger the parts have to be, so they cost more.

Typically, plan on an absolute minumum of about $800 for a VERY simple robot, over half that price being taken up by a speed control and radio package. This is even before you start adding motors, wheels, armor, weapon, etc.

The combat robots I've heard about have ranged from $500 to $70,000, with an average heavyweight 'bot running about $5000 in parts.

The way I usually find it to be is, add up all the parts you need for your robot, make sure to include everything you can possibly think of, now take that number and DOUBLE it. That's about what you will end up spending on your bot. TRIPLE the number for the maximum you should spend. Trust me, it really is like this.

The other, often ignored, expense of building a robot is the actual cost of competing. Chances are the event you are going to won't be down the street, you'll need to either drive your bot, team and tools to the venue, or pack it up and pay to ship it across the country. This can be very expensive and you should price out your options well in advance. Obviously, the bigger the bot, the more it's going to cost to ship frieght.

Also don't forget the expenses of hotels, car rental, food, emergencies, and event entry fees. It is common that a team may end up spending more money AT the event than they spent on their entire robot! Plan in advance and make sure your budget can handle the unexpected, otherwise you're likely to be disappointed.

That still seems too expensive for me, I'm only a kid-what else can I do?

If you are on a tight budget (aren't we all?), figure out how much you CAN spend and buy only items within your means, shop around and get deals on stuff, and try to use materials that you might already have laying around the house or garage or things people would be willing to donate to your cause. In any case, in building six robots so far, I can tell you this:

It's going to cost you a LOT of money, and if you don't have lots of money, you'll have to start saving, right now. If you are determined, you can save a lot more than you'd expect, simply give up some things you currently spend your cash on now, and put it in a bank account or under your mattress.

If you keep this in mind, you will not get too disappointed.You could put together a team of other members who can share the cost. Another option for saving money is sponsorship, talk to businesses in your area about your ideas and show them your working prototypes. Talk to anyone you can and see if you might be able to acquire additional funding. It's not easy, so don't expect a handout.

If that still doesn't work out for your budget, forget about building just yet. GO to a Robot Combat show to see other robots, talk to the builders, take notes and make your plans, chances are you need a LOT of time to think of what you are going to do anyway. And keep your piggy-bank full for your first robot!

What costs the most?

Once again, that depends on what quality you want. There are four things I would really recommend spending good money on: your speed controller, your motors, your radio, and your wheels (this of course assumes that you are using a non-legged robot with DC electric motors instead of gas, hydraulic or pneumatic, of which I know little, so I won't advise you on those here). The best place to find out about pneumatics is over at Team DaVinci, where you'll find an awesome guide to Understanding Pneumatics.

Unless you are an electrical engineer by trade, don't try to build your own speed controller. It is complex and difficult. You can buy some very nice controllers from our MarketPlace, they are prewired to work with your radio control receiver and can handle a fair amount of abuse. I'll go into those a bit more later...

Don't forget to add about $200 or so to your costs for a radio control package. And don't bother with AM, it's against the rules, look for FM, or even better, PCM. Once again, check our MarketPlace pages for some great RC deals.

I get tons of questions on where to find motors. There really are endless sources for electric motors. Junkyards and surplus centers are perfect places for DC motors. Many people even use motors from cordless drills. We carry most of the more popular motors here.

Another thing to spend a bit of money on is a good set of wheels/tires. DON'T use hard rubber lawnmower wheels if you can help it. One key to success at BattleBots is traction, traction, traction! If you can't grip the ground with your tires, you're not going to defeat most opponents. You have to be able to push and avoid being pushed.

Just about everything else in your robot is up to you on how much to spend, but you'll find that usually the more you spend, you'll get the parts that you want and they tend to last longer.

What options do I have when choosing a speed control?

There are now many different kinds of solutions you can use for controlling the speed of your robot's motors.

We list several products by most of the top ESC (Electronic Speed Controller) manufacturers in our Speed Controller section. Check there first. Data and instructions are on each of the pages there.

I can't pay for this myself, can I get a sponsor to help me out?

A bit of advise about robot sponsorship:
1. usually you will not find a sponsor that will help out if you haven't built before
2. unless you are very well established with them, you will not find a sponsor that will give you cash, more often they might contribute some parts or time, and rarely cash.
3. most big companies do not bother with sponsoring robots, you need to look at local shops near you that might like to help out.
4. sending someone an email about sponsorship will almost never work, you have to call or visit them in person.
5. also, make sure your sponsorship is more worth the cost to enter a sponsored robot into BattleBots ($300) as opposed to a non-sponsored bot ($100), if you get sponsored for $200 worth of parts and nothing more, it's not worth it because your extra entry fee will negate the whole thing.
6. Don't give up after getting turned down a few times, you really need to put a LOT of effort into it.

How long does it take to build a robot?

Longer than you might think. But most robot combat robots take around 6 months to complete, although some have taken as little as 3 hours and up to 4 years. It depends on how detailed you want it to be and how well you expect it to perform, and of course what parts you already have. Needless to say, the simpler the robot the less time it takes, and a good thing about those simple robots, a lot of them do very well in the arena, since more complex designs have more areas of potential failure. For your first time around, keep it simple and take your time, you'll be glad you did.

I think I could build one of these things, where do I begin?

Come up with a design. Use your imagination. Almost anything is possible, but remember the more complex you make it, the heavier it gets and the more it costs. If you design a robot that can drive 50mph and has five different weapons and can do backflips and mix a great margarita, you are going too far. Simplify if it is your first robot!

Before you lift pen to paper or cut a single piece of metal, go read Judge Dave's Guide to Winning. This is essential!

Make sure what you want to do is physically and technically possible. A lot of people e-mail me saying things like "I've got this design that has 50 pneumatic spikes all around, crushing hydraulic pinchers, sawblades on the bottom, magnets on the arms, and springs so it can jump on top of the other robot." Get real. Consider what technology exists today, the weight class you are entering, and realize a few things:

-weapons and their control system take up a lot of room and weight
- frame, armor and drive system also take up a lot of room and weight
-wheels, batteries, and controllers also take up a lot of room and weight
-um, is there any weight left to put ANYTHING on your robot? Nope. Start designing something that isn't 1800lbs overweight.

So, after you've decided on some features you want, draw it up! Put it together on paper or on your computer before you start buying parts and putting things together. You may find that something won't work later on and you'll have to start your design over, best to build the whole thing in advance on paper or a graphics program and then start building the real thing only after finalizing your design. My robots went thru dozens of revisions on the computer before I even started building anything!

Another good step is to build a prototype, make a small scale prototype out of wood, cardboard, plastic, whatever you can just to see if the design works. You may end up changing a lot at this stage, so you'll be glad you didn't jump right into the final project at that point.

I can't really say what sort of design works best, but I can give a bit of advice here to make your imagination start jogging: Can your robot recover from being flipped over? If your robot is inverted, can you flip back over or still drive upside down? If not, you might be vulnerable. What about your robot's sensitive electronic components? Are they designed to be located deep inside your robot, or are they near the outside where they could be damaged by an attack? What about your defense to scooping or flipping robots? Can you put on armor that almost meets the floor to avoid such attacks? What about shock absorbing? Can your robot witshstand massive impacts from the side, top, even bottom? How about functionality, shape, style? Do you want your robot to do a certain task? Build it around your idea and see what happens!

Start well in advance. I typically give myself at least 6 months planning and building. If you start early, you can afford to change plans or rebuild things that break. If you start only a couple weeks before the competition, you may not find the parts you need, and you will have no time for one more very important thing- PRACTICE. Make sure you spend a lot of time practicing with your robot. Make sure you are comfortable with driving it and can control any weapon effectively. Use something for target practice and familiarize yourself with the way the robot reacts to different actions.

Last thing for your preparation, (I know I've mentioned it before) Start SAVING your money! I guarantee you will go over your perceived budget in building your bot.

I can't think of a robot design, what should I do?

Oh, come on, you can do it! The best thing to jog your creative talents is to attend a robot competition and see what designs are working, and think of ways you would improve or come up with some way to stop each robot you see. If you can't make it to a competition, I've got an archive of some of the other robots that have competed.

Most of all, check around at all the different robot websites out there. See what everyone else is making and try to do something different (copying someone's design, while flattering to them, is still kind of lame). I have an extensive list of links available to these other sites, start there.

Do I need to build a prototype?

No, not neccesarily, but it does help in the case where you realize something will simply not work in the final design. It really is a pain if you've spent all your time building your final robot and realize that it just won't work and have to start over again. If you're doing it with a cardboard or wooden prototype, it makes it a lot easier to toss it aside and go back to the drawing board.

A good use of a prototype is to test if your motors are powerful enough to move around the weight you are expecting your bot to be, just make a platform with motors, wheels, batteries and speed control, then add weight in the form of bricks, sandbags, scrap metal, whatever and see if your prototype has the power you want from your final bot, if not, its good you only built a prototype before having to replace your entire drivetrain!

And, if you keep your prototypes, they make excellent targets for the final robot to attack!

What tools do I need?

Your brain.
Okay, duh. That's the most important tool for ya. Use your imagination and build the robot in your head before you pick up any power tools. It will save you the time of making mistakes along the way, just sit down and carefully think everything out first, then start building when you are ready.

Other than that, I make it a point to build my robots with ordinary tools that you can find in your local hardware store. Some people use a lot more advanced tools, but I want to prove that any person with access to a good hardware store can build a winning robot. With that said, here are some of the basic tools to consider adding to your shop, living room, garage, whatever:

Saws- jigsaw, circular saw, miter saw, table saw, hacksaw, band saw, reciprocating saw- all these I have and have used in the construction of my robots. You may not need all these, but remember that you'll need metal cutting blades for all the above.

Grinder & files- Invaluable to robot construction. I use my grinder every day while building robots, and what you can do with a simple file is amazing. Get a selection of files small and large, and if you have the luxury of a Dremel or air die grinder, rotary files can save a TON of time (just make sure to wear eye protection!) Oh, and don't underestimate the power of sandpaper if you're using aluminum! A belt or disc sander can come in very helpful!

Cordless drill and possibly a drill press- You NEED a drill and get youself some good metal-cutting grade bits, or you'll be replacing bits far too often. You'll use your cordless drill for screws and bolts too, get a screwdriver bit and socket set for it. If you plan on drilling through hard metals, you'll need some cutting fluid to keep from burning up your bits and make those cuts a lot easier.

Standard issue socket set, screwdrivers, wire cutters and crimpers, soldering iron, open end wrenches, prybar, hammer, rubber mallet, vise grips, pliers, etc. All these you may already have, if not, get 'em!

Workbench with vise- you need a place to put your robot while working on it- working on the floor or the kitchen table is not recommended, go get a cheap Craftsman foldable bench (around $45) and stick a vise to it ($14.99). Half of my robot construction has been on a workbench like this. Oh, get some C-clamps too- they come in very hany to hold pieces down or together while you're working on them.

If you don't plan on putting the whole robot together with screws and bolts, get a welder- Arc welders are cheapest, some can be found under $100, it takes some practice, but the welds are pretty secure. Another method I've used that is not quite as strong is brazing with Mapp gass/Oxygen tanks. I've built two of my robots with this method, and the brazing holds up pretty well under most circumstances (even running into a curb at full speed!). MIG and TIG welding is the best (and most expensive) way to combine your metals. I now use a MIG welder for my aluminum welding, and it works great! Take a bit of practice, but it's well worth it.

Can't I just buy an R/C car and modify it into a robot?

Alright, here's the deal on starting with an RC car for a Battle Robot:

First of all, yes, it's been done before, but only after serious modifications or by entering a seriously underweight robot. In recent years, the competition has advanced far beyond modified RC cars. The only place left for an RC car would be in the under-12 pound weight class, and even then, the opponents you may face there would rip up any standard RC car.

If you want to be competitive, you’ll need to get your bot much heavier than the 2-10 pounds that an RC car starts out as.
The armor has to go- plastic would never last in battle, but you can't just replace plastic with metal, the drive motors in your RC car won't be able to handle the additional weight. Not to mention adding any weapon on the bot.
So, you could just replace individual parts for beefier equivalents, but you’ll find that by the time you get better armor and add a weapon, you’ll need bigger motors to drive it, and of course a bigger speed controller for the bigger motors, and more batteries for the bigger motors, better wheels and tires, a stronger frame to replace that cheap plastic one, an FM radio/receiver (since the AM one that comes standard on RC cards is illegal in BattleBots), and so on, then you realize after all that, there isn’t anything left of the RC car that you started with!

You might as well just start from scratch, but if you really want to, you can experiment by starting with a cheap RC car and building up from there, but don't try using it in battle, it will just break too easily. Just use it for experimentation or for playing against your friends.

Can I buy any parts for my robot from you?

You bet. I've got some of the most common and succesful parts used on combat robots listed in the Robot MarketPlace here, so check there first. You could build your entire robot from parts found in the MarketPlace!

Where else can I get my parts?

Just about anywhere. Look around you right now, I bet you can find 5 objects within 20 feet of where you are sitting right now that would work on a combat robot, you may have never thought of it that way, but it's true. Seriously, when you get in the robot building mode, you look at everything surrounding you and say to yourself "Hey, I could build a robot out of that". Start off by looking around your own house and garage. Look for parts, frame, armor, whatever you think would be cool to put on or into a robot. Expand your search to your neighborhood hardware store, junkyard, electronic surplus store, hobby store, scrapyards and such. You are bound to find TONS of parts you need in these excursions.Your local yellow pages should be your first stop.

Your next stop should be the Robot MarketPlace. After that, go to my links page and click on the suppliers tab. There are a ton of suppliers that will ship you a free catalog, just order some and see what you find.

If you want to be more specific about your parts, definitely check out Grainger and McMaster Carr catalogs. You could probably build a lot of your robot from parts that either of these companies sell from their catalogs. Many of the components from all of my robots are from these sources.

Just use your imagination, there is no limit to the places you can find the parts you need!

How big can my robot be?

There is no limit on size (well, it has to fit through the arena doors- 8 feet across). There are different weight divisions for different robot combat events, but the typical breakdown is three or four weight classes. Typically, the larger ones are harder to build but get a lot of attention, while the smaller ones may not be as popular to the crowd, but you can fit them into a suitcase and get on a plane with them. Here are the BattleBots weight classes:

SuperHeavyweight robots can weigh 220-340lbs if driven by wheels, or 264-408lbs if by legs.

Heavyweight robots can weigh 120-220lbs if driven by wheels, or 144-264lbs if by legs.

Middleweight robots can weigh 60-120lbs if driven by wheels, or 72-144lbs if by legs

Lightweight robots can weigh 25-60lbs if driven by wheels, or 30-72lbs if by legs

As you can see, there is a definite weight advantage to building a legged robot, but there is a reason for that, it is very hard to build and control, and they are not as fast and manouverable as robots with wheels. But, you can definitely do a lot with the extra weight allowed!

Always check the rules of the competition you are planning to attend. Rules are always posted on the event's web site.

What weapons can my robot use?

I get a lot of e-mails from people wondering why we just don't mount shotguns, lasers, and water baloons to our robots. There are things called RULES that we all must adhere to. First, check out the rules for the competition you want to enter, as they may range a bit. BattleBots Rules are here.
You can build a robot combat entry without weapons, but much of the fun is engineering new, unique and useful weapons. Let your imagination go on this one. If you want weaponry, decide what kind you like and research the possibilities. Make sure you stay within the rules (no fire, chemical, liquid, projectiles, explosives, glue, foam, etc).

Here is a collection of tips that I've compiled from a few years in this sport:

Cutting weapons (chainsaws, circular saws, drills, etc), while they usually don't do much damage (they require the target to stand pretty still to be effective), they DO give the bonus of perceived damage (SPARKS), and the audience and judges love it.

Impact weapons (hammers, pickaxes, powered spikes, etc) do more damage directly to the others, but are usually harder to build and make work properly.

Lifting weapons (flippers, lifters, etc.) usually only work well against robots that cannot recover from being inverted, but if your opponent doesn't have that ability, it makes for a good (usually quick) match.

Gripping weapons (grabber arms, pinning weapons, magnets) are usually pretty boring, and have in the last couple of years at Robot Wars become so unpopular that it is now even against the rules to win by pinning a robot. Keep it exciting, don't be afraid to do a little damage.

Wedge. The simplest form of weapon for a robot, and is quite effective. Consists of a slanted front end to ram into opponents in attempt to flip or otherwise disable them. Perfect for a first time entry, as you don't need to engineer complex weapons.

Rotating weapons (spinning discs or bars) are usually pretty effective at pummeling the opposition, but in many cases lose all effectiveness after being hit and slowed down. These usually take a bit to spin up but can wreck havoc when they are at top speed.

Imagine what you would like to see, and try it out. There are countless weapon possibilities, so just make up some stuff!

What does the robot run on?

Well, take your pick...
Batteries- easiest to use, but require recharging and typically, battery powered motors can be a bit weaker.

Gas Engines- high horsepower, but are limited by rules to the amount of fuel that can be used. Also risk of engine dying while in combat- very unfortunate if your robot requres a 'pull' to start...

Hydraulics- high torque and incredible pushing/lifting possibilities. Difficult and dangerous- don't try messing with hydraulics unless you really know what you're doing. I don't know much about Hydraulics. Go to Team S.L.A.M. for info on this.

Pneumatics- Air-powered movement of cylinders or motors- a good clean source of power, but can be difficult to work with. Also faces rapid decreases in power as compressed air tank runs low. Can also be very dangerous.
The best place to find out about pneumatics is over at Team DaVinci, where you'll find an awesome guide to Understanding Pneumatics.

What do I make the armor out of?

Armor's purpose is to protect the internal components from damaging weapons, arena hazards, and exposure to any kind of harm, therefore, you can use just about anything that you feel is strong enough to keep these types of hazards out of the guts of your robot. Armor can range from wood, fiberglass and plastic to lexan and kevlar to steel, aluminum and titanium. In most cases the stronger the armor, the heavier the robot can get. Be sure to choose your armor and the amount you use wisely.

Remember that armor can add a lot of weight to your robot, so be careful to select just the areas that need this protection, some robots don't need a lot, while others may need to be covered on all sides. Be more selective in placing internal components away from potential impact areas, use caution when running your internal wires, think of what would happen if your robot was hit from just about any side and see if wires would short or batteries and controllers would be at risk of damage. Put extra armor (layers or higher grade armor) in the places you worry most about.

What do I use to control my robot?

A radio control system, much like what is used on RC cars, boats and planes, is typically the way to go. Most competitors choose an aircraft RC system from Futaba, Hitec, Airtronics, etc. It is recommended you stay away from AM (against the rules) and FM transmitters and try to stick with a good quality PCM model.

A lot of people wonder about how many channels their radio will need. Well, the basic robot with full steering control to two motors/wheels should only need two channels, but if you plan on using controllable weapons, figure at least one more channel for each weapon or other remotely-activated feature. A 4 or 6 channel radio is a good place to start. I myself use one 6 channel and one 9 channel Futaba radio/receiver package from Futaba to control all my robots.

Check here for a complete selection of RC systems and accessories.

What do I use to move my robot?

Assuming you are going to build a rolling robot (one with wheels and not legs), you can use any sort of motor, or linear actuator to move your bot. Liquid fuel and hydraulic motors are harder to operate, install and maintain, so most people end up using electric motors. Motors are always a sensitive subject with robot competitors. Many will never disclose the source of their motors, because they know that a motor can make or break the success of the robot. You want to choose a motor that is strong enough to not only move the weight of the robot in which they are mounted, but to be able to push, lift, or flip another robot of the same weight. Motors that are capable of doing all this are hard to find and usually expensive and can be very heavy. The dream of every robot competitor is to find the perfect motor that will be small, efficient and powerful. That said, you will likely go through several different motor choices while constructing your robot. One motor that works perfectly in one robot may not perform very well at all in another.

One thing is for sure though, you will need to experiment with "gearing down" your motors to get the optimal balance between speed and torque. This means taking the direct drive from the shaft of the motor, and passing the rotational force through a series of gears, sprockets or pulleys to finally reach the wheel. In most cases, you never want to simply connect a wheel right to a motor shaft. Remember, typically, the faster the motor goes, the less torque (power) you have, and vice-versa. A strong yet fast motor is a treasure indeed.

Gearing down your robot's motors can be done through many different reduction systems. Gearboxes, chains, belts, etc. are all used in gearing down a motor's output to get to the wheels. The gear ratio will most likely take a lot of careful planning and experimentation to get it right, so don't expect it to happen perfectly on the first time.

Another way to get a robot around is by legs. Robots that 'walk' can be very hard to build, and those that can actually perform well in combat are even more rare. Legged robots usually still use motors or linear actuators to move their legs, just in a different way than what wheels do. Builders are encouraged by competitions to build a walking robot by allowing it to compete in the next-lower weight class. A 488 pound walking robot would be allowed to fight a 300 pound wheeled robot! I myself have never built a walking robot (but plan on it!), so I have no further advise on this subject. Use your imagination on this if it is your goal. The rules define a legged robot as one that can move about without the help of wheels. Some great sources for walking combat robots are the Boris robot site, the Stompy site and the Carlberg Creations C2 site.

How does the signal get from my radio to my robot's wheels? I don't understand how this works.

Okay, here's a very simple explanation of what happens:

  1. You push the stick on your RC remote in a direction
  2. The signal is transmitted to the receiver in your robot
  3. The receiver sends a signal to your robot's speed controller
  4. The speed controller, which is also hooked to your battery and motors, knowing how far you are pushing your RC joystick, sends the right polarity and current to each of your robot's motors.
  5. Each motor turns in the direction the speed controller tells it to, thereby turning...
  6. The geardown system (chains, belts, gears, whatever), 'gears down' the speed of the motor, turning that speed into torque
  7. Your wheels, at the end of the geardown system begin to spin, moving your robot.

This situation, of course, presumes you are using a speed controller for your robot. More on how a dual-channel speed control can steer your robot can be found in the next question.

How do I steer the robot? Do I need to steer the wheels like a car?

No. I get this question e-mailed to me a lot, so rather than trying to explain it all by typing, check out the following illustration and following experiment that I created:

Here's a quick and dirty experiment you can run in about 30 minutes to see this in action for yourself:

First of all, let me say this is not the ONLY way you can control your steering on your robot, but it is my opinion (as well as many other competitors) that this is the easiest way to steer your robot. I won't go into the many other ways to steer, since this by far is the most popular method.

What you need:

For this operation, you need to use permanent magnet DC motors. These are the kind of motors that usually have two wires leading into them, if you hook the two wires up to your battery's positive and negative posts, the motor should start spinning. If you reverse the two wires on the battery, the motor will spin in the other direction. If you are using series wound motors, this won't work the same.

In this experiment, you will be building the basic foundation of your robot. You can later transfer this into your actual robot if you wish, but this is just for experimentation purposes.

  1. First of all, bolt your motors securely against a board so they won't jump around when they spin up. Face them in opposing directions
  2. Next, extend the wires of your motors so both will reach your speed controller positioned between them.
  3. Hook up your speed controller RC leads (there are two of them), to your receiver's 1 and 2 outputs. They are usually on the connector, the one with the 'T' goes to 1.
  4. Wire the two leads from each motor to the proper connectors on your speed controller, these are usually labeled Motors A/B. Make sure to wire the motor polarity opposite of each other so they will spin in the same linear direction when facing away from each other.
  5. Wire up your power switch to your positive lead from your battery, run the other side of the switch to the + input of your speed controller. Make sure it is off.
  6. Wire the negative lead of your battery to the - input of your speed controller.
  7. Plug in the small battery pack for your receiver
  8. Double check all your wiring connections and make sure the motors are secure before switching on. Tape anything that looks doubtful.
  9. Swich your power on from your battery. Nothing should move.
  10. Switch on your Radio control. If either motor starts to move, you'll probably need to set one or both of your trims, next to the right joystick on your radio. Adjust this trim until the motors stop spinning.
  11. Push up slowly on your joystick. Both motors will start to spin. You should see that they both spin forward. If you see that one or both of them is spinning backward, power down the system and REVERSE the polarity of that motor's wires that go into the speed controller.
  12. When working properly, you should be able to 'steer' your motors as they are in the diagram above. Imagine how this works when you hook wheels to your motors. That is what steers your robot!
  13. If your system does not work as pictured, there may be other factors, try these:
    Turning off the built-in mixing on your radio's channel 1 & 2,
    Experiment with the reversing funtion of the radio's channels 1 & 2
    Reverse the speed controller inputs 1 & 2 that are plugged into your radio receiver

There you go. That should help you understand how this 'tank-steering' works. Even if you don't have all the items needed, you should be able to picture how this works in your head. If you still don't understand, you really need to try it for yourself.

**Optionally, you can use two single channel speed controllers and set up the 'mixing' on your radio, but for this illustration I use a Vantec RDFR series speed controller.

Should I be taking pictures or video while building?

Of course! You need to be able to document the progress of your construction, if not to show to others at the events and on websites, then for your own journal and ability to look back at any mistakes and accompilishments. Keep a camera near your work area, and if you have a camcorder, videotape yourself working on your robot. Have someone tape you practicing your robot and repairing it. There will be lots of opportunities to share this kind of recorded imagery with other builders and the media, so don't let good stuff go unrecorded!

I don't really want to build a robot, but I want to come see you smash yours up, is that okay?

Sure! Stay tuned to the What's New page and BattleBots site for upcoming events.

As far as actually coming to my shop to see the robots in person, I'm afraid I simply don't have the time, but make sure to stop and say "Hi" to me at the next competition!

I heard that Robot Wars was having some problems in recent years, what's going on?

Yes indeed. Robot Wars (which started all this back in '94) began having problems in 1996, when a dispute broke out between the partners that owned it. Countless court cases later, and cancelled 1998 and 1999 events, the organization as a whole was crippled by the dispute, Robot Wars has basically met an untimely death. Only time will tell what actually happens with this event, thankfully, there are alternatives out there such as BattleBots.

If you want to read more on this subject, please check out my History page, and there are even more details about the problems surrounding Robot Wars in my journal archives at the bottom of the What's New page. Also, I've been tracking a bunch of public announcements and legal documents made available on the case on my Letters page.

What's the story with BattleBots?

Up from the ashes of the legal mess surrounding Robotic Combat, comes an event that promises is designed FOR the competitors, as it is founded BY a competitor. Trey Roski and Greg Munson, creators of the incredible LaMachine robot from past RW events, started BattleBots in 1999 with a prime focus on the robot builders instead of the money. You should definitely check out the BattleBots website for all the most current information.

BattleBots is currently THE event to go to in the U.S.

I heard you make the best robots around, is this true?

Uh, yep. Yeah, that's it....

Well, I like to think so. My wife does too ; )


What's up with the not-so-gold 'Golden Nut' on BattleBots?

I get this question a lot, so I decided to answer it here. BattleBots has ONE large golden nut (about 60lbs), it is gold only in color, but is made of aluminum. Nobody gets to keep this nut (it's rarely even seen), but the idea is that winners names from each season get engraved onto it, kind of like a "Stanley Cup" kind of thing.

The winners of the events get their own nut to keep though, this one is a smaller (around 20lbs and 10 inches tall) nut, is silver in color, and has either "Duel Winner" with the weight class, or "Rumble Winner" with the weight class. Bots winning the votes on "Coolest", "Most Aggressive" and "Best Engineering" get a nut like this too.

Second place winners (runners up), also get a nut. Smaller still, this one is about 5 inches tall and 4 lbs.

How does the BattleBots show I see on TV work?

One very common misconception about the show you watch on TV is that what you are watching is happening recently. Hence I get emails saying things like "I saw last night on the show that you fight ___bot next week, here's some advice...".

The reality is that what you are watching on TV happened many months ago, and not over a once-a-week thing either, one match you might watch one week may have actually only taken place 5 minutes after a match you watch on an episode weeks later. For Season 1.0 and 2.0 of BattleBots, the entire season was taped over the course of ONE weekend! Season 3.0 was over 5 days of actual competition, but the matches get strung out over up to 15 individual episodes, lasting several months. Meanwhile, the bots you are watching on TV may have been totally rebuilt, or even destroyed by the time you see them on the screen.

Other myths about the BattleBots TV show that are important to note:

How does the BattleBots scoring system work?

BattleBots judges score a match only if the fight did not end in a Knockout. If the outcome was a Knockout (the other bot was incapacitated and unable to move by the end of the referee countdown), then the last bot moving is the winner.

If, however, the match goes the full 3 minutes and both bots are still moving, the judges score each robot according to 3 categories: Aggression, Damage, and Strategy. Each judge distributes 5 points between the 2 bots for each of these categories. For example, 'Bot 1' might have done most of the damage during the fight, but not all, so the judge might award 'Bot 1' with 4 points, and give 1 point to 'Bot 2' for damage. The totals for all categories and all 3 judges are added up, and the total always equals 45, so the score you might hear on BattleBots will be something like 30-15, or 22-23, or 45-0. The bot with the higher number is declared the winner.

When is the next BattleBots?

Always stay tuned to the BattleBots web site and my What's New page to know when the next event is going to be.

How did you do at the last BattleBots?

Every competitor signs a NDA (Non-Disclosure Agreement), so that after a BattleBots event, they are not allowed to publicly share the results of any of the fights. So, even though the winners will have been decided months before, nobody can say anything about it until after it has aired on the TV show.

For previous show results, I usually give a good description of the fights in my robot's individual pages.

I can't make heads or tails of your tips, where else can I get some more information?

Check out all the other robot combat related pages on my Links page. Everything you need should be accessible through the multitudes of links there.

Here are some other great sites with tips:

Team Delta
Team Saber
Wedge of Doom

Good luck and enjoy building your robot!