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Robot Wars

The Tech sport of the new millenium.

By Brett Paulin

Of course for most of us, that's all we do. Watch. Actually getting out there and competing in aggressive physical sports requires a lot of training and exercise that we intellectual technical types are usually allergic to - until now.

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He's called "The Judge" - but he's also the jury and executioner! In combat, all of the exposed mechanics and electronics are well hidden and well protected.

There's a new contact sport out there and you can be the champion of it without straining any more muscles than you need to win on your PlayStation.

It's called "Robot Wars", "BattleBots" or just plain Combat-Robots.

It's the sport for those who like to battle with brains rather than brawn but still want the adrenalin rush that comes from savagely rending your opponent limb from limb, without risking so much as a personal scratch in the process.

Robot Wars is the ultimate "boys toys" sport, at the same time as being one of the most intense engineering challenges and learning experiences you can find. In principle, it's simple.

It's Robotic Darwinism or Survival of the Fittest. You create (cue Thunder-roll and Mad Scientist Laughter) a heavily armed and armoured remote-controlled destruction machine and unleash it upon your opponent in an arena where two robots enter and one robot and a pile of scrap is left at the finish.

Of course, that's exactly what your opponents have in mind for your machine as well - so your mechanical monster had better be tougher than theirs or it will be going home in a robotic body-bag.

Some drivers have compared the adrenalin rush that comes while competing in these events to sky-diving or professional drag racing. Others love the intellectual challenge of building a machine and putting it on the line in a life-or-death match.

And all competitors agree that the planning, design engineering, materials science, machining skills, electronics, strategy and just straight cunning is the most enjoyable and creative learning experience they know of.

How did it start?

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...into the valley of death, they rode... These hydraulically-operated crusher jaws can (and do!) operate with a force measured in tonnes and are designed to disable an opponent robot by literally crushing it to death.

Back in 1992, a US engineer tried to radio-control his vacuum cleaner to make house-work more interesting.

After viewing the resultant destruction wreaked in his living room, he decided that it was so much fun, that he would organise a competition for people to pit their radio-control creations against each other.

Several years down the track, there are now two major TV shows, thousands of competitors, a wealth of websites, PlayStation and PC Video Games, remote control toys, Internet Chat Forums, and even McDonald's happy-meal plastic toys of the most Famous BattleBots in America.

The sport is continuing to grow and diversify as people push the boundaries of what can be done with machines to destroy other machines.

Watching machines beat the bolts out of each other is a hit. It has Quality Violent Destruction and no one gets hurt, physically, that is. Economic? That's another matter!

Australia is just starting to catch up with the rest of the world in this new sport, with new teams in every state forming and building their first robots, and starting to organise local events with a view to holding a national event soon.

The Channel 10 network has been screening the UK "Robot Wars" series while waiting for the sport to grow locally. Welders are arcing and soldering irons are smoking as the first generation of uniquely Australian robots come to life.

Are they really robots?

Are they really robots? A common question, given that most people think of C-3PO or Terminator when imagining a robot and something that looks like a remote-controlled ditch-digger doesn't quite qualify.

Well, being remote-controlled (by a human!) they are not autonomous, so full-on robots like C-3PO might be affronted but if C-3PO wants to argue about it, then he had better bring along a light-sabre to do so, because these robots are NOT the sort to politely disagree.

There are "Autonomous" (self-directed) classes but that's a subject for another article. For the moment, remote-controlled machines are where the real excitement is, since they have a cunning human brain behind the steel muscles and the action is a lot more "personal" in nature.


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"Maximus" is a classic flipper-type robot, intended to disable the opposition by turning it upside-down.

Rules? Well, yes, there ARE some or it wouldn't be long before someone equipped their robot with hand grenades or a Tesla coil and vaporised everything within sight. This is supposed to be a FUN sport and having to compete and watch from a concrete bunker in the desert via TV wouldn't quite be the same.

Basically, "Kinetic Energy" weapons are the norm - things that smash, cut, rip, flip, puncture and crush. Saws, hammers, spikes, flippers, wedges, drills, flywheels, clubs, pick-axes (no, not the chip) and any other destructive or fiendish implements you can devise are permitted.

Prohibited weapons include explosives, electrical discharges or radio jamming, chemical/corrosive substances, nets, fire (in most cases) and radiation of any sort (lasers, masers, gamma beams etc).

Why? Safety is the first reason - your rocket launcher or napalm-gun may sound like a cool idea, until it misses its target and hits something else. Hopefully, whatever else it is will be strong enough to stop it before it then hits a spectator, so long-range weapons are out. All projectiles must be tethered to the robot.

Second, entertainment is the name of the game. Watching one machine rip chunks of steel off another with a saw is much more fun than a light tap with an electrode bearing 100kV which instantly fries the electronics and leaves a visually undamaged robot sitting still like a stunned mullet. Likewise radio jamming is banned as there is little point in having robot machines helplessly twitching, with the fighting going on in a realm that can only be seen on a spectrum analyser. Most of the prohibited weapon rules are either for your protection or your entertainment.

You will be amazed at the wide variety of machines possible within the scope of these rules. Every competition reveals a new idea that has competitors re-designing and re-engineering their machines to meet the opposition's latest threat.

The rules vary slightly from competition to competition, since some allow flame throwers and some don't; some allow internal combustion engines (ICE) to power spinning blades, etc and others are worried about the fire hazard they present. Some events are limited by the strength of their arena walls, so have a maximum weight class they can handle. At one event in America recently, a super-heavyweight Hi-Speed (150kg) Rammer Robot missed its target and smashed clean through a foot-thick brick wall into the car park!

A basic rule set that most events build on can be found at the American Robot Fighting League (RFL) website at

Types of robot

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The "pits" at a typical Robot battleground. You'll find every possible configuration of robot, in all weight categories, with every conceivable (and probably some inconceivable!) weaponry and defence mechanisms.

So, you have an unbeatable design in mind? Most effective robot designs fall into a few major categories, each with their own strengths and weaknesses - although sometimes a new design will appear that defies description, so this is only a rough guideline. Feel free to innovate and come up with something that does not fit into any of these pigeonholes to surprise your opponent. Just make sure your "secret weapons" will pass the safety rules.

Wedges - the simplest type of robot, basically a mobile door-stopper, low to the ground to get under the other robot, scoop them and push them around the arena - hopefully flipping them over. Often sneered at since they don't have an active weapon, they are still popular since they are the easiest to build.

Lifters - like a wedge, with the addition of a moveable arm that makes it easier to either flip the other robot over or lift them and pin them against the wall. These are very effective against robots that cannot self-right or drive inverted but ineffective if their opponent has either ability.

Flippers - high-powered lifters, usually driven by compressed gas pneumatic rams, often capable of tossing other robots high into the air and causing massive damage when they crash back to the ground. These can be very dangerous and tricky to build unless you have experience with high-pressure gas.

Rammers - powerful, fast bulldozers are designed to shove the opponent around the arena, into the walls and physically slam into them at high speed to cause damage; often fitted with spikes and wedges to penetrate the opponent upon impact.

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"Bone Saw" - aptly named, because it could!

Spinners - the masters of destruction, fitted with high-speed spinning flywheels with cutting or bludgeoning teeth on them. They cause massive damage and sometimes rip pieces off the other robot and send them flying. The bad news is that they often break themselves as well, since the law of action and reaction means they absorb the same impact energy back into their own frames. There are limits on where they can compete though, since bulletproof arenas are required to protect the spectators from flying fragments.

Hammer-Bots - swinging sledge hammers and pick axes. These are impressive but difficult to build, since accelerating heavy hammers quickly and repeatedly requires ingenious mechanics and powerful motors. Often, they are powered by pneumatic rams like flippers - a very effective design when done well, since many robots have weak overhead armour and sometimes the hammer can be used as a self-righting mechanism as well.

Crushers - Hydraulic-powered presses, sometimes with penetrating spikes to concentrate the forces into a small irresistible point. Not a very popular design, since their jaws move very slowly and it's easy for an opponent to escape. They also require careful engineering of their frame to withstand the enormous forces they have to exert without bending.

Circular Saws - visually exciting, often sending off showers of sparks, they usually also require a way of temporarily immobilising the opponent, since it's hard to saw something that won't sit still. Clamping jaws of some sort make them a lot more effective.

Thwack Bots - an unusual type of spinner, the whole body of the robot is spun around by driving its two wheels in opposite directions, with a hammer or spike on an extended arm. The principle is that all of the robot's spinning mass goes into the impact. The drawback is they can't move around while spinning, so the opponent often just sits back and waits for them to stop spinning before attacking.

Weight classes

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Is that really a lawnmower blade up front? Sure is - but don't try mowing your lawn with this one!

The biggest rule is WEIGHT. Obviously, there have to be limits here or someone would fit a remote control to an M1 Abrams Tank and laugh while picking bits of the opposing robot out of their treads after the match.

To keep things (relatively) sane, all robots have to fit into a weight class, and are only expected to battle other robots of the same class. Your robot can weigh anything up to the maximum weight for a particular class. If you go over it, you are up into the next class and will be battling much fiercer machines, so keeping an eye on your machine's weight is most important.

The accepted weight classes are:

Ant-weight:             0.5kg
Beetle-weight:            1kg
Hobby-weight:             6kg
Feather-weight:          12kg
Light-weight:            25kg
Middle-weight:           50kg
Heavy-weight:           100kg
Super-Heavyweight:      150kg

Naturally, the heavy and super-heavy classes are what most people dream of building, since they are the most destructive and spectacular. They are usually the ones that get the most TV coverage.

However, they are also the most expensive by far. Motors, batteries and electronics that can muscle 150kg of steel about at high speed are not cheap, and you will probably have to settle for something lighter to start with. The Feather-weight class (12kg) is looking to be a very popular class to start off in within Australia, with the robots still big enough to be impressive but small enough to be manageable without a crane and a trailer. When was the last time you tried to move a 150kg machine around your workshop? Feathers will fit on your workbench, in your car boot and cost a lot less to build with more easily available parts. You can always scale up later if the bug really bites you.

How much does it cost?

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Some combatants really go into it in a b-i-g way. This pantech is the mobile workshop for the Team Van Cleve in the US. (

As far as hobbies go, this is not a particularly cheap one, unless you stick to the lower weight classes. The ant and beetle weight class robots can be built for around $200-$300 with modified hobby servo motors, cheap radios and batteries being sufficient to power them. You can have a lot of fun in these classes and they are perfect for dads to screw together on their electronic workbenches with a soldering iron and hot glue, for their kids to battle without breaking too many expensive parts.

The hobby and feather-weight classes start to get a bit more expensive, since you need more powerful motors to carry the extra weight, bigger batteries and some serious electronics to handle the higher currents to power these motors. Add in multi-channel radio control and you are probably heading for $1000 without too much trouble.

From Light-weight and upwards, costs really start to climb, unless you are willing to do a lot of scrounging in junkyards and surplus shops for used parts. Fortunately, here in Australia where the sport is just starting to take off, the level of competition isn't very intense yet, andyou have a reasonable chance of winning with a machine cobbled together with your home welder, using salvaged metal and motors. In fact, that's how most of the robots here are made now.

In the USA, some of the top-ranked heavy and super-heavy weight machines have cost up to $45,000, with CAD designed, custom water-jet cut parts carved from blocks of ultra-strong titanium alloys, custom-wound electric motors and CNC machined gears and drive-trains. Some of the teams show up with semi-trailer workshops and team uniforms, since there's national TV coverage and fame to be had for winning the championship at the bigger events. Sponsors will often weigh in with money and parts to help out the top TV teams.

Back in Australia, we haven't reached that level of professional competition just yet, so now is a good time to get into it and have a good time relatively cheaply before the players with big dollars move in and start to raise the competition level bar.

Robot electrical systems

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Of course, major damage does occur...

Most combat robots are powered purely by electricity - batteries, permanent magnet DC motors and electronic speed controllers. Some more advanced designs use petrol engines, pneumatics, hydraulics and other technologies which we won't go into right now. Electrical robots are the simplest and easiest to construct, the most reliable and the safest. They are probably more likely to be of interest to readers of this magazine.

The components that make up an electrical combat robot can be split up into the following categories.

Power source

In most cases, this means batteries. The most common types of batteries used in combat robots are either "SLA" (Sealed Lead Acid) or Nickel-Cadmium (Nicad) batteries. They need to handle heavy sustained discharge currents for five minutes, while still being reasonably lightweight and physically robust.

Radio control system

Most combat robots use model car or model aircraft radio control systems to drive and actuate their weapons. A basic ramming or wedge robot will need a two-channel system to drive the left and right motors. Weapons require additional control channels to activate.

Drive control electronics

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...that is the name of the game, after all. It only takes one wrong move to get your robot caught by an opponent. The idea is to be more agile, have more power and weaponry and give the opponent minimal opportunity to cause you damage.

The Electronic Speed Controller (or ESC) takes the pulse output from the radio receiver that is normally used to drive servo-motors and converts it into a bidirectional, pulse width modulated signal. This is then used to drive high current Mosfets to vary the power applied to the drive motors, to move and steer the robot.

Weapon control electronics

Most of the time, robot weapons can be activated with a simple relay or two. You will need some electronics to change the receiver's servo drive signal into a relay switch. Some speed controllers have these built-in, otherwise servo relay adapters are available from radio control shops (like Silvertone Electronics).

Electric motors

Depending on the weight class, these can range from small hobby motors up to huge 15 horsepower beasts that draw hundreds of amps. Combat robots are usually made from motors adapted from some other application to keep the costs down. Popular motors can be obtained from battery-powered screwdrivers and drills (since they include gearboxes), windscreen wiper and car thermo-fan motors, and even electric wheelchairs and golf buggies.

Wiring and isolation

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Here's a typical carbon dioxide (C02) setup for flipper control. Remotely cont-rolled via radio, it gives a sudden and powerful lift to the flipper mechanism.

The wiring of a combat robot is critical. Remember this thing is going to be pounded on, crashed into, flipped, crushed and spiked.

The number one cause of failure of most combat robots is wires coming loose under the forces experienced. Also, the wiring must incorporate a safety isolation switch to totally disable the robot (for obvious reasons) and be able to handle the large currents needed by the motors in shoving matches.


In addition to the physical isolation switch to remove power, all robots require some electronics to ensure that if the radio-control link is lost for any reason, it will return to a safe (deactivated) state. Commercial units are available for this and some speed controllers have them built-in.

More information

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Lightweight bot "Backlash" can inflict some heavyweight damage!

A recent interesting development is the inclusion of Combat Robotics as an approved school curriculum course. Engineering teachers the world over are finding it's a great way to interest students in robot mechanical and electrical/electronic engineering. So many school or class-based teams started appearing at the events in the United States, that a special "Battle-Bots IQ" organisation was formed specifically to encourage young builders to do a school-approved course. Studying a wide range of engineering disciples is necessary to build a robot, with the culmination of the course being to construct and compete with a BattleBot at an event.

This course has proven to be enormously popular. It is hoped that something similar will occur soon with the TAFEs and universities of Australia seeing the opportunity to encourage young minds in this rapidly growing field of robots.

Well, that about covers the basics of Robotic Combat. The rest is up to your imagination!

There are a number of "forums" where you can chat with other builders and enthusiasts, surf a plethora of web-sites with detailed build reports, guides, frequently asked questions and parts for sale. In addition, quite a few builders use MSN Messenger or ICQ for online chatting about what's going on and to keep in touch. To help you on the way, here is a list of the best places to find out more about Robotic Combat.

Australian Sites - a Melbourne-based group of builders, (including the author of this article!). Check the links page for connections to other Australian-specific sites and contact details for the other Australian builders. We hold regular meetings where builders can get together, help each other out and view videos of the latest events from around the world. - an all-states group with a good chat-forum/bulletin board to discuss building online. - a new site, aiming to compile information on the robots and teams from around Australia; not much content yet but one to watch in future.

International Sites - the leading Robot Combat website. Also the Team Nightmare website, with a huge automatically-updated daily links section to practically every other robot-related website out there, allowing you to find the latest news and content quickly. It also incorporates the Robot-Marketplace where you can find everything you need for Robotic Combat, parts, books, videos, motors, and more. - The producers of the BattleBots events and TV show in the United States. - The producers of the Robot-Wars TV show in the United Kingdom - The US-based on-line chat forum; great technical info here.


Thanks to Jim Smentowski of, John Mladenik and Don Shiver for permission to use their robot photos from around the world.

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