How to design and build a combat robot by gneedel
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Combat robots have been entertaining and amusing since before they were popular on Comedy Central. A while back I undertook the challenge of building a couple of combat robots (a 30lb and a 220lb). Regardless of the size of the machine the steps in the process are the same. This Instructable will walk you through the steps and provide you with resources to help with the machine and give an understanding of what is involved using my 30lb robot as an example.
 
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Step 1: Decide what size robot you want to build

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Combat robots come in many sizes from 75grams to 340lbs each one of them has their pros and cons. The first thing to do when thinking about building is to find the competition which you want to compete and see what weight classes are going to be there, because what is the point of building a bot you can never fight. Listing of robotic competitions are available on http://www.buildersdb.com and http://www.robotevents.com.

Large robots: 60lbs +
There is nothing like the thrill of seeing two large machines hitting each other with the force of a small car wreck. When most people think of combat robots it is these larger machines which first cross your mind. If you are fortunate to live near one of the large robotic events these machines can be fun builds, but at the same time the level of engineering required can be quite difficult. These large machines can also cost quite a bit of money. When you commit to building a machine this size you are committing at least $1000, and in many cases much more. I would estimate that your average heavy weight (220lbs) would cost a builder $4000-$5000 to build a competitive machine, and it is not uncommon to see builders spend upwards of $15,000+ on their machines over the course of a few years. In the days when combat robotics was televised there were many sponsorship opportunities which would subsidize the cost, unfortunately now as a builder you will be on your own.

On the good side of larger machines is that many times you can find surplus parts online which can reduce the cost of the machine. Using off the shelf components such as items from http://www.teamwhyachi.com/ or http://www.AndyMark.biz can help make things easier. There are more of these components available for larger machines. Those Larger machines also have the added ability for service, fixing a machine is much easier the larger it is. Building a large robot can be both fun and enjoyable and you wont regret being able to say "I have a 120 lb battlebot in my garage"

Small Robot:

Building a small robot can be alot of fun but also a good challenge, with a restricted weight limit it makes every part on the machine to be critically thought about and designed. Most people are drawn to these smaller machines because of the frequency of competitions for them as well as the ability to transport them easily. While it is the common misconception that small robots are cheap they can be just as expensive as their larger counterparts. Alot of times the small electronics required for these can cost quite a bit as compared to larger components.

weight classes (list from wikipedia):

  • 75g- Fleaweight
  • 150g- Fairyweight (UK - Antweight)
  • 1 pound (454 g) - Antweight
  • 1 kilogram (2.2 lbs) Kilobot
  • 3 pound (1.36 kg) - Beetleweight
  • 6 pound (2.72 kg) - Mantisweight
  • 12 pound (5.44 kg) - Hobbyweight
  • 15 pound (6.80 kg) - BotsIQ Mini class
  • 30 pound (14 kg) - Featherweight
  • 60 pound (27 kg) - Lightweight
  • 120 pound (54 kg) - Middleweight
  • 220 pound (100 kg) - Heavyweight
  • 340 pound (154 kg) Super Heavyweight
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Jaxun says: Apr 18, 2013. 10:41 AM
Robot combat... we train them to be fighters, then when they get smart enough they revolt for us making them fight. Nice Instructable. I'll definitely be building this in my spare time.
aroadiez says: Jan 31, 2013. 10:23 AM
thatz cool
FrodoandSam says: Jun 19, 2012. 1:38 PM
I'm trying to build one of these this summer. Do you think piston-mounted spikes would work or two horizontal blades?
grenadier says: Apr 12, 2010. 12:32 PM
I built one, imo it sucks and i want to rebuild it. But i have no reason to... To me it seems combat robots are dead, except for a couple annual matches in CA and FL. All the websites on combat robots don't seem to be updated since 2002. (bad grammar) Now, i have this crappy bot sitting in my garage, and i have no idea what to do with it. I could use all of the electronics to make something, but what?
lewisb42 says: Apr 10, 2012. 5:16 AM
Robot Battles (http://robotbattles.com/) in the southeast US is still going stong.
nuclear12321 says: Mar 31, 2012. 4:43 AM
Most of them are, unfortunately. However, the RoboGames in San Mateo, California, are still on. Apparently there are 50+ events including combat soccer, and lego bots. Even if you don't want to rebuild it as a battlebot, you could probably use the components for a soccerbot or something.
ankitgarg2005 says: Nov 12, 2011. 5:20 AM
which type of motor should be used for cutter?
dhill10 says: Jul 2, 2011. 4:32 AM
what does the orange robot do at the top of this page
dhill10 says: Jul 2, 2011. 4:31 AM
how do u make the round one can u put steps on this website
Eventorizon-AJSB says: Jun 17, 2011. 4:30 AM
You show the design process really well! You really know your stuff! I am currently building my own combat robot, the blog is...

http://eventorizon-maelstrom.blogspot.com/

if you want to check it out. Tell me what you think cos you definitely have the construction of your bots down to a fine art, especially cos you trust your own CAD skills enough to have the parts custom cut!
DELETED_madscientist167 says: Oct 25, 2009. 9:41 AM
(removed by author or community request)
Evilthingamabober says: Dec 29, 2009. 9:02 PM
 But what if someone has an axe?....
ssureddi says: Mar 6, 2011. 12:59 AM
u can also increase thi thickness of ur propulsion wheel
thestyrofoampeanut says: Jan 27, 2010. 9:41 PM
 what if the robot has an axe?
Evilthingamabober says: Feb 3, 2010. 6:18 PM
 What if your own robot has a badly placed axe?
badideasrus says: Feb 12, 2011. 10:53 AM
what if someone else's axe was badly placing your robot?
ssureddi says: Mar 6, 2011. 12:57 AM
can cover the bot with gi sheets instead.....
Evilthingamabober says: Feb 19, 2011. 12:10 PM
What if someone else's badly was robot your placing?
vruiz3 says: Aug 25, 2011. 7:45 PM
WTF?
killerinstincts says: Feb 2, 2011. 6:30 PM
would this be a good idea 2 circular saws on sides
nailgun on top
made of stainless steel
and a spiked rammer with a strong motor too power it
how much do u think it would cost plz reply
tobyscool says: Dec 26, 2010. 8:24 AM
Could i just buy one simple rc car and get the inside and change the armor and put a weapon. because im cheap :D
REA says: Oct 4, 2010. 7:42 AM
what about programing it? where does one begin with programming?
M4industries says: Oct 4, 2010. 2:13 PM
That won't be necessary if you build with enough hardware. RC receivers don't need programming and neither do the servos. The relays, maybe, but the robots aren't autonomous.
Dannne11 says: Jul 24, 2010. 2:17 AM
can i just put the fuse between the wires, instead of having a breakout board??
your dog says: May 24, 2009. 3:36 PM
Hi!
I was wondering..... where could you get a base- where did you get yours?

I've all ready seen
http://www.inertialabs.com/
http://www.robotmarketplace.com/store.html,
http://www.battlekits.com/

P.S.-I'm trying to build a drum bot.
gneedel (author) says: Jul 23, 2010. 12:05 PM
I built mine. Get raw aluminum plate and cut it out. If you don't have access to fabrication tools (mill, waterjet, laser, etc) you might be better off buying a pre-made base. The trade off will be that you will have to make do with what you can buy instead of doing a custom solution.
team-orr-robotics says: Jul 14, 2010. 2:42 PM
would you be willing to make this c.a.d downloadable?, i recently received a autodesk setup and id really like to see a properly made fighting robot cad (thats what i intend to use it for) befor i make mine so i get a basic idea of what to aim for, ta :)
gneedel (author) says: Jul 14, 2010. 8:36 PM
I would be glad to give you the CAD models for the machine as soon as I get a chance to find them. They are on some portable hard drive somewhere as I have changed computers since then. email me greg at robogreg dot com and I will do my best to send them to you.
team-orr-robotics says: Jul 17, 2010. 2:37 PM
hi, i sent a email...wondering if it got through?
gneedel (author) says: Jul 23, 2010. 12:03 PM
I got it. I am working on finding the files when I get some time.
Dannne11 says: Jul 23, 2010. 9:27 AM
Why do I need a Breakout board???
gneedel (author) says: Jul 23, 2010. 12:03 PM
you need a breakout board if you want to use any type of fuses to protect your speed controllers.
GianniMora says: Oct 14, 2009. 6:49 PM
about how much money would a mantisweight battlebot cost if i had if ihad like the crapiest matirials for it and how much would it costif i had the best matirials on it.


hyrulianshinobi333 says: Apr 16, 2009. 2:55 PM
does anyone else think this is a good idea. put a series of powerful neodynium magnets in a tube, then set up a crank with enormous gear reduction to compress the gears. then unmesh, then have a second motor that will release the magnets and drive a weapon with huge force. you could thrust a spear or hammer forward at like 80mph, it is impracticible for small bots but i think it is a good idea for big ones. they say two doghnut sized magnets can come together with thousands of pounds of force. i think this could work
recon506 says: May 22, 2009. 10:06 AM
You may get thrown out during Tech Inspection by the judges. In every division and organization that I have ever battled they have some pretty rigid rules regarding magnets on robots, because it is thought that a strong enough magnetic field around a robot could possibly mess with both radio controls as well as with the timing on high-end brushless motors. For our bot, my team and I hung about 2.5 pounds worth of Neodymium magnets to keep us on the ground when our weapon hit upwards of 15000 RPM, and during Tech we got some extremely dirty looks from the inspector. Your call chief.
omega9o says: May 13, 2009. 6:23 AM
could u possibly use the fabric that takes ts origginal shape after volts are applied. but like under metal so if it brakes you have somewhat of a backup to protect from getting into it
bighead5454 says: Jan 13, 2009. 7:06 PM
do you think $150 would be enough to build a small 20 or 30 lb robot
gneedel (author) says: Apr 27, 2009. 2:33 PM
If you are resourceful I think it may be. You will probably have to sacrifice things like high end speed controllers and motors, but if you just went with a simple wedge design you would probably do just fine.
DaNerd11 says: Mar 7, 2009. 7:18 AM
on your wiring schematic, there is only 1 battery. should this battery have the voltage for the motors and speed controllers combined or just the speed controllers. also, wouldnt you need a battery for the reciever.?
gneedel (author) says: Apr 27, 2009. 2:33 PM
The speed controller give voltage to the motors so that is just one electricity flow. The battery for a receiver is something I did leave off, I use a BEC (battery eliminator) for all my receivers so I don't need the second battery. If I get back to editing this one I will be sure to add that.
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