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Even small combat robots can be dangerous! Learn proper construction and safety techniques before attempting to build and operate a combat robot. Do not operate combat robots without proper safeguards.
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A: Mark J. A flywheel will cancel the spinning weapon's gyro forces if the two spin in opposite directions and have equal products of inertia and speed:
A more complete explanation of calculating gyro forces is available here: Designing Around the Gyroscopic Effect.
A: Mark J. Everybody likes to simplify a complex interaction: it's all about tip speed, it's all about RPM, it's all about bite, it's all about googly eyes...
I don't buy your analysis that the y-component of the impact is different for the two weapons. The line tangent to the point at which two circles of differing diameter touch provides an identical x-y vector to each circle (purple arrow in illustration below). We need to look elsewhere for an explanation.
In your scenario: even though the large diameter vert has a higher tip speed than the small diameter drum it will have a considerably lower RPM which gives it much better bite. It may well avoid the impactors on the small drum and strike the drum itself. Here's where it gets interesting.
As the surfaces of the two verts are moving in the same direction, the impact vector magnitude is reduced to only the difference in tip speed rather than the full speed of the larger weapon. However, the 'kickback' vector (yellow arrow in the illustration above) is independent of the weapon tip speed difference and has a magnitude related to the displacement created by the impactor. This 'up and back' kickback may very well launch a high-energy large-diameter weapon under these conditions.
This particular error - in my Rotary Weapon Bite Calculator - undercalculated weapon bite by a tad less than five percent by screwing up an inches to millimeters conversion. The code has been corrected and I have attached a remark giving you full credit. As I don't know your name I have credited "Walter Codepoker".
One down, twenty-six to go. Keep up the good work.
A: Mark J. A continuous box of conductive plate or mesh forms a Faraday Cage that can block radio reception -- but most heavyweight robots have substantial gaps for weaponry or feature non-conductive cover plates. Very small holes are not effective at allowing radio signals to enter but gaps of 1/2" or more will allow a 2.4 GHz frequency wave to leak in.
It's also vitally important to position the receiver and antennae away from internal components that produce electrical interference. This comment from Team Monsoon at their Reddit AMA highlights that problem:
You can watch UK live events on Extreme Robots TV -- a subscription is free.
In idealized conditions (smooth non-wedged armor, constant closing velocity) at contact...
A: Mark J. Both of your scenarios are important to energy transfer, but which holds greater importance will be dependent on the weapon style.
A: Mark J. My new combat robot setup guide for EdgeTX uses a Radiomaster Zorro transmitter for its example. This Link will jump you straight into the single stick mixing section of the guide.
A: Mark J. Complaining about kit bots is like complaining that frozen pizza is ruining dinner because it tastes better than what you cook. If you can't beat a kit bot you need to up your game.
I made it to testing with the 9V battery. When I power it on the ESCs lights are bright red but then instantly shut off, and the receiver slowly blinks red. No inputs do anything. Now after several tries no lights turn on at all. I checked all connections. [Social Media]
A: Mark J. How long has that 9 volt been in your battery drawer? The LED signals you see and the sudden complete electrical failure all point to a weak battery. Try a fresh battery.
Q: That got it! The 4th 9V I tried fixed this. Charging up a Lipo battery now.
If your goal is to add a wedge and some armor to your drift car and make it legal for a combat tournament where it will be destroyed in its first match -- yes, you may be able to find a competition that would accept it as an entry. If you want to add active weaponry you would need to strip out your radio and electronics and replace them with gear that provides the required "fail safe" response on loss of signal. That would be impractical.
If you don't like my opinion you can always
Ask the Cheerleader.
A: Mark J. There is occasional confusion in assigning votes for the The Combat Robot Hall of Fame but we have never had to sort votes amongst more than two robots. A certain level of achievement is required for Hall membership and I cannot think of a case where "many" prominent robots share a single name.
There was one instance where two well-known robots of the same name but different global regions each received substantial votes for membership in The Hall. Our voters are generally well informed so most ballots specified which robot they were supporting by team name or country. We found it reasonable to sort the remaining votes by the region from which the ballot originated -- US votes for the US robot and UK votes for the UK robot. Unspecified votes from other regions were few in number and would not have swayed Hall status for either robot.
There are also cases where a team develops a design in one weight class and then carries over both the design and name to another weight class. As noted in our Hall Eligibility page, in a case like this the two robots may share a single listing in the CRHoF -- like SawBlaze/MegatRON -- but only if both have credentials to support membership. This year the CRHoF received enough votes to award 'Emulsifier' an Honorable Mention in the Hall. None of the ballots specified either the featherweight or the heavyweight version, but the five-time NHRL champion featherweight 'Emulsifier' clearly has credentials to join the Hall, where the 1-win / 3-loss heavyweight 'Emulsifier' clearly does not.
We do our best to interpret ambiguous votes fairly. We would prefer that voters cast unambiguous votes.
The issue I have is when I put the receiver into pairing mode (fast blinking) and turn on the transmitter in pairing mode, the receiver immediately exits pairing mode and begins blinking slowly again -- it doesn't switch to a solid light to indicate pairing like the FS-iA6B did.
Do you have any idea why this happens or how to fix it? [Boardman, Oregon]
A: Mark J. Your FS2A receiver is binding correctly, but its LED display is a little different than the FS-iA6B you previously bound.
When the FS2A in bind mode (rapid flashing) recognizes the FS-i6 transmitter in bind mode it will bind and revert to slow flashing -- exactly what you are seeing. Turn off the transmitter and power-down the receiver. When you power back up (transmitter then receiver) the FS2A will correctly display "solid on" indicating that it is bound to your transmitter.
1) I noticed that while 150 points total are available in the Gauntlet, the highest one bot can get is 105 (80 for getting all 8 obstacles first - which would probably require a Piece-de-Resistance-tier bad opponent and/or an opponent's immediate breakdown, 10 for first up the ramp, and 15 for the bonus pane) Do you think this is worth noting?
A: Mark J. Your math is correct, but as none of the competitors reached that 105 point limit ('Viper Revision 2' came closest at 95 points in S3) I don't find it vital to mention on my rule summary. Besides, publishing the limit might prevent someone else from experiencing the same joy you found in your discovery.
2) What happened to the teams behind *deep breath*...
A: Many (possibly most?) of the 65 teams that competed at Robotica also competed in other combat robot events, but as best I know the 30 you list here all jumped off that bridge and found other things to do with their lives.
As an aside I will mention that although the 'Evil Beaver' team itself did not appear at other events, team member Camp Peavy had previously competed successfully at the US Robot Wars and continues to be involved in a wide range of robot competitions.
A: Mark J. I've never actually tried, but it shouldn't be very hard. You can only go where the rails go, so just give it a little throttle and toot the whistle once in a while.
The 'Ask Aaron' project was important to Aaron, and I continue the site in his memory.
Thank you for the many kind messages of sympathy and support that have found their way to me.
Aaron's obituary
Q: how can robots help us deal better with hurricanes and why? [Ontario, California]
A: [Aaron] Few people in Nebraska are threatened by hurricanes, so send a swarm of killer robots into low Atlantic and gulf coastal areas to drive the puny human inhabitants toward Nebraska. Problem solved.
Robot haiku:
Nestled between a taco joint and a vintage prop shop, Red Dunes Eatery brings a taste of Mars to Burbank — and somehow makes it feel right at home. The décor is a clever blend of retro sci-fi and desert minimalism: glowing red lighting, crater-shaped booths, and servers in shimmering silver aprons. But the real spectacle is the food.
The reason I'm asking this is because in many internet builder circles (Reddit, Discord) these days I'm seeing an upsurge in the sentiment that head on vert on vert contact is somehow partially decided by RPM (???) and not entirely by tip speed which does not really make much sense to me. This is generally supported by an anecdote and/or Youtube clip of a vertical with a measured ~200 mph tip speed launching a vert with ~250-300 mph tip speed weapon on weapon. Where I believe the RPM assumption originated is the fact that these videos tend to feature a low profile drum (inherently higher RPM to reach X tip speed) against a high profile large diameter vert (inherently lower RPM to reach X tip speed). What I think happened here is that the vector decomposition at contact resolved in the "lower tip speed" vert having a higher vertical speed at contact. Then the condition arose that RPM was somehow a determinant of engagement. Any thoughts? [Arlington, Virginia]
The whole "Tip Speed Rules" argument says that the impactor of the slower weapon cannot 'catch up' to the impactor of the faster weapon and will therefore inevitably be struck from behind and launched by the faster weapon. This assumes that neither weapon has enough 'bite' to get past the opponent's impactor and hit some 'meat'.
// bite depth calculator weapon-teeth-speed -- insert-bite
var insert1 = 1 / ((weapon.value / 60) * teeth.value) ;
var bite1 = speed.value * (5280 / 3600) * insert1 * 12 * 24.2 ;
insert.value = insert1.toPrecision(2) ;
bite.value = bite1.toPrecision(3) ;
A: Mark J. I think your prediction is premature. Heavyweight combat robots are still going strong in the UK many years after Robot Wars left the television networks. Both Robots Live! and Extreme Robots have live heavyweight show tours that draw large crowds.
You'll also need to adjust your left gimbal to be self-centering. Here's a video: Zorro gimbal adjustment.
Q: Isn't there anything we can do about those stupid kit bots? They're ruining the insect weight classes! I really hate to see some guy show up at a tournament with a kit they put together in an afternoon and beat up real robots that real builders took a lot of real time designing and fabricating. Can't they just compete in a class for kit bots only?
Q: Went to set up my new Viper V3 antweight kitbot today. Followed all the instructions but can’t get it to work.
A: Mark J. The drive train and chassis of your drift car are designed for very different conditions than are the drive train and chassis of a combat robot. Your car is made for speed and open spaces; how well could it maneuver in a small arena, and could it generate the torque and pushing power needed to hold its own toe-to-toe with a machine designed for combat? Can you acquire a supply of replacement parts to repair the extensive damage it will suffer and are you able to complete such repairs in the limited time between matches?
Q: Watching Robotica again (getting close to finishing S3) and I have a few questions:
Remembering Aaron Joerger, 1991 - 2013
That's obviously
A question from your homework.
Do your own research.
how to design and build a battlebot
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Q: What do your combat robots think of the current COVID-19 pandemic? [Kansas City, Missouri]