Building a Winning Combat Robot - Split

Split is my attempt at a more meta style machine known as a '4WD Vertical Spinner'. This type has theoretical advantages in damage output and control, but theres more to building a robot than the concept. The robot is built from a mix of steels, carbon fiber and plastics designed to maximise durability and deliver a destructive Eggbeater style weapon. Entered into the 150g Robot Wars/Battlebots competition in wollongong, we'll see how my machine does against strong competition.
End of video fight montage music: Battle! Penny by Noteblock • Battle! Penny - Pokémo...

[@MakersMuse]

Damn you Split! You cost me $4 in motors :P

[@-NGC-6302-]

I have noticed a positive correlation where if something is fun to use, it tends to be annoying to others Split looks very fun

[@ellabun]

"woueauh aaaah woaaah uuh ow woaah" "Is that Angus woahing in the background???"

[@MakersMuse]

@@ellabun split very woahh

[@TrentSheather]

It would be cool to see a breakdown of where your weight budget goes for this and other robots. Perhaps a pie chart that shows the weight of each component and the mix of frame, weapon, power, and electronics elements.

[@scotty6435]

Your driving control is absolutely phenomenal! Very measured but relentlessly aggressive. Could you do a fight video with a split screen showing your controller? It would be interesting to see how you control like that. Maybe a vid on ESC/controller tuning?

[@BrokenLinkRobotics]

I'll see what I can do, need two cameras to record both a match and my hands. Will bunch a TX-ESC tuning segment into a video at some point.

[@claudiusraphael9423]

​@@BrokenLinkRobotics Or use your smartphone as second/IP camera and use the opportunity to create a "Robust Adjustable Gimbal Exterior - RAGE" for all smartphones in existence ... casually, alongside .. YKNOW?!! AND THEN AND THEN : ... Change Robust to Robotic. Drool. Drip.

[@kurage_medusa]

16:55 "Smack it into the wall, put it back in" lol

[@Shovel________________]

i find it funny how just flopping around until you're back on your wheels is actually a viable enough self righting solution with how light these bots are

[@rancidmarshmallow4468]

if there's one other thing to do, tighten up those forks! they flutter a lot with the weapon vibration, which is common. mounting them fixed in thin, flexible TPU pieces with a bit of preload or adding small torsion springs to keep them pressed to the floor will make getting under anything and everything more consistent.

[@BrokenLinkRobotics]

I did try spring loaded forks on this robot, but even with the lightest heat-shrink springs it took too much traction off the front wheels and made it hard to drive. It worked great on other robots though, may move to grippier tyres and try again.

[@rancidmarshmallow4468]

@@BrokenLinkRobotics gotcha. At least here in the US I can find tiny little metal torsion springs that are great for this, and the force they put on the forktips can easily be adjusted by changing where the fixed side is anchored or bending the legs into the right angle.

[@815TypeSirius]

​@BrokenLinkRobotics you can do the same thing passively by using an asymmetrical front weighted fork. It will just naturally lever down. Need more torque to actuate it though.

[@robotwarsluvr]

Let someone else win in Wollongong for once 😂 All jokes aside split is terrifying to fight but such a fun robot to watch

[@roboman2444]

4wd semi-invertible 'drum' spinners have been a solid design choice for many years now. I remember there being a TON of them in the 12 and 30 pound classes back in the mid-2000s. Not much has changed since then.

[@factslogic5964]

A video on your CAD though process would be good

[@newmonengineering]

Awesome winning streak. I like the design, and it seems very stable and steerable which is key to getting into the correct position for atrack

[@Hilshoist50]

Another great video James, keep 'em coming.

[@gerbil7771]

As much as you make a great little bot your driving is stellar. You out drove all your opponents thoroughly.

[@PCBWay]

This is SO good, do more uploads pls! 👍👍

[@SethMarcell]

Very cool!

[@notoast4u]

16:55 "smack it into the wall" lmaooooo

[@plasmapanasonic4741]

Very cool to see this sort of vid, from omeone whis thinking about tetting into the hobby

[@MGFDLR]

That thing is mega powerful, you hit them like a riptide 😉

[@jimbotron8552]

Would love a more detailed breakdown on what parts you used and how much every part weighs.

[@vincentlewis93]

Well, I'm looking forward to scale 3 fights on the videos next

[@Spiethstar]

Cool machine and video. It might be a good idea to keep the axle the weakest link. Cheap and easy to replace, right? The materials used in thes machines makes the last so long. Amazing Looking forward to see more.

[@saxon215]

Every Aussie who isn't from SA knows that Adelaide is just a fever dream you get from crossing from WA to the east

[@kerobotics2657]

I love it, what is the weapon made of?

[@ScarletFlames1]

The only weapon I've never seen before is a shredder, like a paper shredder but for plastic. It would be a fantastic counter for all those plastic robots if you can make it happen within the weight limit. Although without having to counter strong gyroscopic movement maybe it'll allow you to skim weight off in other places? A nimble attacker that grabs enemy (plastic) armor and just eats them, the concept sounds awesome in my head.

[@AJB2K3]

I thought I heard Angus there

[@gtdgabriste1]

I would love to see your cad thought process on one of these. Do you start with the known parts and expand from there? What software do you use? Do you start with pen and paper? Algorithm.

[@BrokenLinkRobotics]

I arrange the basics in space and make a rough shape, then add or subtract from it. Modelled in Fusion 360. Will do some CAD stuff in a segment soon enough. Algorithm?

[@pseudo.Random-KF]

2:43 From my understanding of physics, both types hit with the same force. The only benefit of a upwards vertical spinner is the added stress of gravity on your opponent. Since the force that sends your bot down is only cancelled by the earth, the only gain would be added control of the bot when attacking, as well as a possibly advantageous angle to attack from. However, there is a weight cost of the infrastructure required to withstand both the force from the attack and the force from the earth.

[@pseudo.Random-KF]

Looking at that battle footage, though, it seems like that added control allowed for more hits on target, so thats another plus

[@pseudo.Random-KF]

A downwards vertical spinner would seem like the way to go, as it forces more energy to be transferred each engagement, but it will send the robot upwards, losing control. This could be mitigated with more weight, but I wouldn't know.

[@hugh_jasso]

With this design you could switch to mecanum wheels and get another degree of control with side to side motion.

[@skyriftnetwork]

Have you thought about using a carbon fiber plate to cover your batteries and electronics instead of ABS? i feel like that's a pretty big weak spot (if it was to be hit there)

[@thomashp]

Great robot! Just curious what rpm n20s are those?

[@BrokenLinkRobotics]

3v 1000rpm N20s

[@ivanivan9507]

Hi. Nice combat robot. Do You have rpm reduction on BLDC motor for weapon?

[@BrokenLinkRobotics]

4000kv at 8.4v

[@DazsdWTP]

that chainsaw robot should be called "sit stihl"

[@onearth...]

my idea - use a verry fast bot that uses a verry long thread in which the opponents get entangled....

[@l8dawn]

Where did you get the beater? you said it was from SCS but it looks EDM/milled which SCS doesn't offer

[@BRICKCELLPHONECOLLECTOR]

I have a question about the emax 1407 brushless motor. Im building a eggbeater 200gram antweight combat robot and i would like to know if this motor is good? 4000kv is very high and im woried if it is powerfull enaught to spin up 60 gram eggbeater. i see it worked for you perfectly but mabye you know better options? Would really apriciate if you would answer

[@BrokenLinkRobotics]

@BRICKCELLPHONECOLLECTOR Probably fine, just don't expect to run it at full power all the time. I usually stick to ~60% unless need be.

[@deucemoose7852]

I know jack squat about the mechanics of which I'm about to ask, but is a slow crushing style of attack (like what you'd get with pneumatics or those hand leaver can crushers) viable at this kind of weight class? I'd imagine anything that could do proper damage is either too slow given that you can't hold something for more than 10 seconds, or too heavy, but it seems like that's an angle of attack I'm not seeing represented. Would be interested to hear your thoughts.

[@BrokenLinkRobotics]

@deucemoose7852 Totally, the thin plastic top armour of almost every robot here would fall quickly to a crusher. The challenge is generating that sort of force at this weight class with enough spare to armour up.

[@deucemoose7852]

@BrokenLinkRobotics thanks for the insight, haha!

[@Why-Not-Robotics]

at the moment trying to go to a fight in Adelaide or Sydney how do you travel with lipos and the robot in general

[@jameskirby9981]

There are guidelines on how many or how large the batteries can be, but crucially all terminals must be covered with eg. electrical tape and the batteries must be stored in a Travel Bag. The bag is lipo fire-proof and can be purches for cheap from places like nextfpv.

[@Lusidous]

So I just caught your video and had to ask. So you had your weapon made out of 4140 steel, did you have it hardened or just go with raw 4140? How did the weapon hold up?

[@BrokenLinkRobotics]

Raw 4140. Held up very well, did the same with the Beetleweight. Wears out faster but is very tough. Getting hardened weapons is very expensive in Australia.

[@TrentSheather]

What is the limit for your weapon shaft diameter? Jake Hoffman made a point in his maximiser build that by changing his weapon shaft to a larger diameter hollow shaft he could have a stronger shaft with the same weight. The equations and explanation were 1min 55 into his upgrading maximisers weapon video. kzbin.info/www/bejne/hH62mYqcbNKfmrssi=V4Qu9O0UPAGptkHL

[@BrokenLinkRobotics]

Currently the beater has 3*6 ball bearings, so 3mm limit. The maximiser shaft is a solid design, but is less and less sensible as the length increases for the weight. Bumping up to a 4mm shaft will be lighter than a hollow say 8mm Alu axle that needs much heavier 8mm bearings and larger beater mounts. Very good concept for horizontals though

[@SpiderWaffle]

The forks are bouncing around a lot, you could try adding some small torsion springs to them or just make them part of the chassis with no hinges. Maybe reduce the span of the beater bar slightly (stear a little better and don't need all the that span) to bring the forks in to center more and mount them more robustly. To be a bit more like Synthesis: kzbin.info/www/bejne/h6vHeaqgp7eYmrM

[@GrowingGiants]

where do you make your weapons? Do you make them yourself?

[@BrokenLinkRobotics]

Mostly machine them myself, this eggbeater is the only time I outsourced (PCBway)

[@GrowingGiants]

@@BrokenLinkRobotics thank you. Do you have the cad files for these? I’d like to make this bot for my kid I’d be willing to pay you for them.

[@Galileocrafter]

Is there something like this in Europe? I‘d love to build robots and fight them.

[@BrokenLinkRobotics]

Surely, where specifically are you at? There are combat robot clubs all around the world

[@Galileocrafter]

@@BrokenLinkRobotics Switzerland, specifically.

[@BrokenLinkRobotics]

Hmm nothing came up with a quick Google, might have to look at a bit of travel. Not sure how easy that is for you. Alternatively you could start a club but that isn't an easy option either. I could've sworn I watched a video about someone running an antweight competition around there though.

[@Galileocrafter]

@@BrokenLinkRobotics Well, I had the same experience, tried googling but no results so far. I'm starting to think, that there is nothing.

[@BrokenLinkRobotics]

Might be active on Facebook, but not looking great. Good opportunity to start a club though! Or just travel abroad but not sure how easy that is ever there. Hope you can find something that works

[@endertyplays7981]

you should fight cheesecake

[@Lumakid100]

Different weight classes. US Antweights are three times heavier than in the UK and Australia.

[@pgmusic1]

Can I get your chassis and weapon degine .. I

[@BrokenLinkRobotics]

It's on Grabcad

[@815TypeSirius]

If they dont have to be electric you could own with a methanol powered bot.

[@EskildAnd]

What would happen if your drum was turning the opposite direction so the energy from the weapon was not used to distort and flip the opponent but only to destroy🤔

[@TimInertiatic]

he would throw himself in the air on every hit

[@emilandersten1331]

The opposing force on split after a hit would, instead of being absorbed into the ground, throw split backwards and up. Bad for both impact on landing and he might end up in the pit.

[@gtdgabriste1]

Watch bb season 7. I forget which fight, but copperhead used this as a strategy to make weapon on weapon hits hurt the other guy... seemed to work for him...

[@Starwort]

0:25 absolutely criminal that Carbide wasn't included here (even though it's a horizontal spinner rather than a vertical one)

[@watsmyu989]

Oooooh, may i give a bot idea? If so, please click read more. A bot designed to take weapon on weapon hits. And a name suggested. MASOCHIST.

[@BrokenLinkRobotics]

Dont want to take the idea from you now, it's a pretty good name

[@watsmyu989]

​@BrokenLinkRobotics sorry about completely denying what you said, but unfortunately, It will be like 3 years until I can make bots out of things that aren't Hex Bugs. I can't afford much so I make with what I have

[@BRICKCELLPHONECOLLECTOR]

is it really 150 grams? its very hard to believe to be honest. Prove it. i make antweights myself and its very hard to believe that eggbeater is more 150 grams

[@BrokenLinkRobotics]

If it was not under 150 grams then why was it allowed to compete in multiple 150 gram robot events

[@BRICKCELLPHONECOLLECTOR]

im just curious i know its 150 grams but its hard to believe i would like to know how you putted all that in that small weight. @@BrokenLinkRobotics

[@BRICKCELLPHONECOLLECTOR]

very impresive@@BrokenLinkRobotics