Editor’s Note: Today we welcome a guest blog from Team HUGE member Peter Lombardo, talking about the breakout event of his unique 3-pound robot, Bee-Roll!
Wow what a day! Bee-Roll has been cooking for years now and it's really nice to see it finally getting up to temp. The February 1st NHRL event was a whirlwind of activity, and while I didn't get as far into the bracket as I would have liked, it was truly an ideal day of robotting.
To start off, here's a slice of Bee-Roll, that I think shows off most, if not all of the design elements. The power comes from a 4s 850mAh battery in the center, through a Fingertech Robotics switch, into two ESCs (Repeat Robotics DESC, Neutron RC or Just ‘Cuz Robotics Pariah, depending on the mood) powering 3536 1000kv motors, and a smattering of support doodads (BEC, indicator LEDs, ELRS Lite R/X).
The entire external body and wheels of the robot is 3d-printed from bouncy TPU rubber for toughness, and the internal electronics cradle is made of a stiffer 3d-printed nylon.
As everything needs to fit within the diameter of the weapon, packaging is critical. Back when the robot competed under the TTPR name with a solid aluminum tube, the battery compartment also contained the ESCs, tucked away on either side of the battery, with the radio bits over by the battery connector. For the printed version known as Bee-Roll, I had a little more flexibility with packaging. The ESC controlling the motor next to the switch actually lives in a separate compartment under the battery, which in theory reduces complexity and at least protects the battery from the heat of one ESC. The other ESC goes over the top of the battery. Again, space management is critical here (this is important later) and everything fits exactly where it needs to go with just a little room for wires.
Fight 1: Wreck Creation
Wreck Creation is a Peter bar kit, which is fearsome in its own right, but is also expertly controlled and a real menace in the arena.
At this point, I'm still learning how this robot drives, so the idea is to stay on my toes and have fun with it! There were one or two moments where the tube fully spun down after a hit, this (I think) is due to induced voltage spikes causing the BEC to briefly cut out. This has been a bigger issue with my old radio (QX7 ACCST) where the connection just wouldn't come back. For this event I tried out a RadioMaster Boxer on ELRS, which was happy to reconnect, although it takes 3-5 seconds. I had seen on the NHRL Discord that folks were using TVS diodes to chop off the tops of voltage spikes, but I was able to burn out the diodes while bench testing the whole system. Further testing is required to get the right setup, but I’m happy to know that the ELRS setup will at least reconnect!
This was one of two fights today where I took serious damage, and the only one where I had to repair the damage in the pits. This meant extracting the still-functioning motors from the cracked battery cradle and installing them into a new cradle with a new wiring harness. Thankfully, the harness was already made. But it took the better part of an hour to forcibly disassemble the cradle and remove the motors after I stripped the screws. Space is tight in there!
The lesson here is:
Don't design things that are difficult to put together and take apart, and
If not 1, maybe have some more spares and have them installed before you get to the event.
I sure hope it’s easy to remove the motors!
It was not easy to remove the motors.
Fight 2: Ratfish
Ratfish is not just one, but a series of robots in multiple weight classes, featuring long forks, big durable wheels, and reliable lifters.
The beetleweight version of Ratfish is also an equal weight multibot, making it the first multibot I've ever fought! Focusing on one thing at a time has never been my strong suit, so I'd have to bee on my best behavior, focus on one robot at a time… and did you know that Ratfish uses dyed UHMW as their lifters? We had a great conversation while waiting to fight about what kind of dyes work best with UHMW, and what kind of mixes you need to get the colors you want. In this case, they matched the orange of their compliant wheels with some red and orange dye, as just orange turned out too light. Wait, what was I talking about? Yes! A multibot!
Ratfish was incredibly, frustratingly consistent, keeping their forks pointed right at me, and while they didn't stop my weapon, they were able to get a few pins started, and a worrying amount of control against a robot as chaotic as Bee-Roll. Luckily, they experienced some drive issues later in the match and I was able to buzz out a JD.
This fight was powered by a Dual ESC that is not particularly well suited for running weapon motors; even the manufacturer suggests keeping it turned down or only used on drive. But it's so dang compact that I couldn't pass up trying it. I had my current limit turned down from 70A to 50A, and turned down my rates in the radio so the motors should be drawing less than that. Still, the ESC got hot enough to melt its hot glue potting to the inside of the tube, a failure mode I should have anticipated. The innards were eventually removed, with help in the form of a dead blow hammer. But for lower speed control, it worked great!
(“Potting Compound” is a lie told to limit your usage of hot glue)
Fight 3: Orcas
Orcas are a new entry from the builder of the frightening YEETUS, and as an overhead saw multibot they represented a major threat to my everything.
There are points on my robot where the batteries are no more than a half inch from the outer walls, and even their smaller saws could slice right through that with ease!
In addition to their excellent teamwork game, their baleen-style front wedges showcased one of my shortcomings with the design of Bee-Roll. I don't actually get a lot of bite. The heads of the 7/16 flathead bolts are less than an inch wide, and protrude about 3/8 inches up from the body of the tube. See below for all the black and white scuff marks showing where I gummed their tpu wedges instead of grabbing and tossing them. Still, I popped them up a few times, wasn't pinned, never spun fully down, and again scraped by with what I can only imagine was a really narrow JD.
All those scuffs under the letters could have been hits, but it’s also super cool to see the engagement visualization, almost like flow-vis paint on a race car. Also when the robot hits the floor and launches back, it usually ends up with a bolt tooth full of floor! I have to remove the bolt entirely to get all the wood out.
And remember when I said I was trying a new radio for this event? I found a fun little issue with it right before this fight. I have a model for each copy of the robot, as they all use different speed controllers and motors, and all require specific mixing to match speeds. Well in the line to load into the box, my first model, the one I was using, returned to default settings! Mixes, outputs, even the name of the model, all gone. As quickly as I could, I bodged together something to get the wheels to start spinning at the same time. What I realized later was that this limited the speed of the green wheel to about 80%, and the yellow wheel was unlimited. So that's why the green wheel looks like it's dead for the second half of the fight, even though it's still spinning.
The bane of my existence. Model01 used to be “BEE ROLL” with models and mixes all set up. Once it becomes “MODEL01”, it’s got nothing.
Fight 4: Eruption
I'm not going to lie, I made dinner plans with my family when I saw I was fighting Eruption.
Eruption has a long and extremely successful track record at NHRL. I was going to lose every tip speed engagement, plus they have the control, and they have the mobility. What I wasn't expecting was how instinctual of a driver Brian would be. For example, about 30-35 seconds into the fight, we go weapon to weapon and I pop up in the air maybe 1-2 feet. In my head, I'm excited not only that he didn't roof me, but also that me coming down from that height would be enough closing speed that I could actually impart some good energy into his top plate or bunny ears. Imagine my disappointment that not only did Brian anticipate that whole little fantasy I had going on, he had already backed up to avoid it by the time my eyes went from my robot to his.
I'm not sure I'll ever get to that level of competitiveness and situational awareness, and I think that's okay. Y'all are built different, and it's incredible to see. Anyways, a few seconds later one of my wheels was unceremoniously torn asunder and I tapped out as soon as I could, giving Brian the well deserved win and ending my run in the round of 32.
Maybe Alloy 910 nylon with only 3 walls isn’t the move.
These axles were ejector pins from amazon, made of 65MN steel, they’re not going to bend but they sure will break. This is the second time I’ve broken a shaft like this, there will have to be a better solution going forwards.
Note to self: Real life isn’t supposed to look like a cutaway view
Conclusion
What a day! I learned a ton about competing, about pit management, time management, preparation for an event like this, especially as a solo event. HUGE thanks to Mouser Electronics for supporting Team HUGE throughout the years, to all the lovely folks who shared their time with me during the event, and to my endlessly supportive family for putting up with my unrelenting nonsense. I'm taking a break for now, but will keep cooking in the background and be back later in the year.