Check out this fight highlighted in BattleBots Season 6, Episode 11, or here on Youtube.
Another year, another tournament! We’ve never missed the season’s-end tournament in our four years competing at Battlebots, but this is the first time since 2018 where we’ve really felt confident about our weapon going into the bracket. With the right string of matchups, a HUGE-type robot can be a force in any bracket, and this year’s is no exception.
To start off with, we have to face the feared Uppercut, one of the most destructive weapons in the field. If we thought Switchback was a test for the chins, then Uppercut will be that, doubled! Uppercut is coming off of a 2-0 regular season, with knockout wins over Gigabyte and Free Shipping. We’ve also fought both of those teams, winning by judge’s decisions in 2019 (against Gigabyte) and 2018 (against Free Shipping). They’re a destructive tall vertical spinner, with the fastest weapon spinup in the field, so nearly a worst-case-scenario for HUGE. Past fights have taught us that our path to victory is by out-reaching other vertical spinners, and by being able to withstand a few blows to the body. We were confident in our reach, and just had to cross our fingers that we could take the hits from Uppercut.
This fight was scheduled for early in the session, on the day immediately following our wins over Retrograde and Switchback, so another quick turnaround. After getting as much sleep as possible, we returned to the filming venue for repairs and preparations. First on the list was replacing a loose wire from our drive system, which caused our intermittent drive against Switchback. Next, we replaced the damaged front “chins”, and went with a double-thickness chin rather than the single-thickness we ran against Switchback. The weight for this modification came from running a plastic top plate on one side of the frame, as we consider Uppercut too dangerous for any of the top armor we have. So why waste the weight!
On to the fight itself… this kind of performance is exactly what the changes to HUGE were made for. We dodged a box rush, raced around the box, and blasted our opponent across the arena! The path to success in the current “meta” has only become faster and faster, and we need to keep pace in a field of faster robots and weapons. In comparing notes with the Uppercut team, we learned that our spinning blades store roughly the same amount of energy. Normally HUGE’s energy is spent more on slicing rather than throwing (based on the specific design of our blades), but it shines through when hitting an object as solid as Uppercut’s weapon system. Sadly, our electronics just could not withstand Uppercut. We were concerned before the season that our switch to new brushless motors and controllers (which was changed prior to the 2020 season) had not been truly hit hard during that season’s fights. The issues against Switchback heightened that fear, and Uppercut served to confirm it. That said, there was a ton to learn from this fight, and a lot of things that went very right for us.
Takeaways
Internal component safety
HUGE has historically enjoyed good reliability of internal components, but they had never been tasked with taking hits like the ones from Uppercut. We had hoped that the chins would keep Uppercut away from hitting the underside of the frame, which was not the case. However, they did unexpectedly catch Uppercut’s hits and prevent them from cutting into the frame at all. As a result of catching the hit, all of this energy became an upwards “punch” rather than local damage. The underside of the frame was dented up slightly, but the real damage landed within our drive speed controllers.
On both drive controllers, this surface-mounted component (which supplies power to the onboard computer) tipped off the board. With the orientation of the controller within the robot, the component tipping to the right is indicative of the upwards punch from Uppercut. Due to our redundant electrical systems, there is no single component that can be damaged enough to disable HUGE’s entire drive electronics. But suffering an identical failure, twice, simultaneously, on well-padded controllers is apparently something that Uppercut is powerful enough to inflict.
In reviewing this failure with numerous other teams using the controller (a Trampa VESC6 Mk.3), we found that teams largely fell within two camps. Those who glue/epoxy this component permanently to the board; and those who were intimidated by the fragile thermal pad connecting the controller to the case, and did not want to run the risk of damaging it. This incident carried us away from the “intimidated” camp, and we were determined to find a solution. Every working speed controller we owned was opened up and carefully epoxied, necessitating a replacement of the torn thermal pads in each. We used this thermal pad from Amazon to replace it. The key elements being the 0.5mm thickness, 6W/m.k thermal conductivity, and being a large enough size to do many controllers at once (each controller requires roughly a postage stamp of material). This was used for the rest of our fights during Battlebots filming, with no failures or overheating noticed. We hope that sharing this experience will make other teams feel less intimidated by the internals of the electronics, and lead to more reliable robots in the future. In the end, we were surprised at how easy it ended up being.
In past years we have used MG Chemicals 834FX Potting Compound for our electronics, with good results (besides the chemical burns…. buy long gloves). We hope that, with more curing time than an at-event repair, we can move back to a fully-potted strategy to protect electronic devices.
Other than the damage to our speed controllers, the only other internal damage was this slightly curved/bent battery, one of 12 batteries inside of HUGE. This still worked, and in-fact was not noticed until after it was recharged and we were packing batteries inside the robot for our next fight. It was discarded with the help of the Battlebots safety team, who deserve more credit than they ever get.
Tegris Is A Great Material!
The chins! Viewers watching closely will notice chunks of tegris mounted underneath our body during the fight against Switchback, and here against Uppercut. Tegris is the material that we have been trialing for wheels and legs, top plates in certain fights, and a material seen readily used on Mammoth in 2021. It’s an amazingly tough woven polypropylene, which ends up 20% less dense than UHMW while being significantly stronger. This means we can use more of it in the places we need it most, while also providing better protection. The total weight of four “chin” pieces underneath the front of HUGE was just 5 pounds, and it was able to fully catch Uppercut’s spinning blade, preventing it from piercing into our frame. Consequently, all of this force was distributed into such a concussive shot that it dented in the base of our frame, squished a battery, and killed both drive controllers. Maybe we should have let them just cut through instead (joking). There’s a lot to learn from this, and it will be put into building more effective armor configurations in the future.
A close view of Uppercut’s hit under the chins. Click HERE for a quick video showing the damage.
Uppercut provided a great cutaway view, showing the layered nature of tegris.
HUGE hits hard (and so does Uppercut)
One of our concerns after fighting three rookies during the regular season was that we had no experience hitting our blade against the armor of more experienced teams. Getting a chance to fight such a highly-seeded team is an opportunity to compare yourself against the best robots, and learn more than you otherwise could. This is consistent in the tournament every year, as our matches have only been against the best of the best! Bite Force in 2018, then Whiplash in 2019 and 2020. In this fight, HUGE damaged Uppercut in a variety of ways during 45 action-packed seconds. We ripped off external supporting poles, tore up a tire, and most crucially pushed Uppercut’s weapon shaft out the side of the frame. By a combination of missing support poles and disabled weapon, we were able to disable Uppercut by knocking them onto their side.
A broken support “horn” from Uppercut
Uppercut’s weapon shaft, knocked out the side of the frame. Uppercut did not appear to be spinning properly after their first hit on HUGE
When Uppercut raced into the rear of HUGE, it forced our support leg into our own blade. This chopped the leg (note the blue paint), partially tore out the leg-mount, and twisted our frame. This would not have directly caused HUGE to split, but did weaken the structure. This was never an expected failure mode and is really only a result of the tougher legs; chopping off our legs against Malice did not cause this failure of the center-mounts. We have ideas to prevent this failure again in the future.
Leg mount partially torn from the frame
Did we mention that Uppercut hits really really hard? We’ve never seen a robot scoop a chunk out of our weapon like this.
Conclusions
All in all, we see 2021 as a very positive season for HUGE. The growth we’ve shown, the damage we have been able to inflict, and the shift in strategy have all given us a lot of confidence for future seasons. Three knockouts in the last three fights is an amazing achievement considering that we scored just two over our first three seasons. We feel that the losses to Riptide and Uppercut were due to issues that we can resolve quickly, and we’ve gained helpful experience protecting our electronics and body within the last two fights. But hopefully, we don't have to find out if these changes work anytime soon…
…
…
Oh you’ve got to be kidding me.
If you need me, I’ll be cutting out more chins.