Our latest update comes with a ton of information so here goes!
Yeti has been working hard to prototype several solutions for the first week and we broke into smaller teams to accomplish this goal. Our thoughts on our design direction - use whatever we have available with a mostly rookie team and try to Recycle Rush our way to completed designs.
How we prototype is kind of weird to anyone passing by, or maybe not? We have several wood drive bases that are cut to scale that represent our robots. Someone recently called it “Wood Coast Drive” we might keep that!
For the last to years, every robot has started out as a little frame, including SubZero here with the wood twin.
The first thing we noticed about this ball during prototyping is that light compression seems to work quite ok. Our roller prototype was designed to see how much compression it takes to sling the ball through our various subsystems to decrease cycle time. Initial measurements say that about half an inch or so works with our little flex wheels but more tuning is required. With that in mind, we started prototyping intakes using some of our old Whiteout (2020 robot) intake copies. Turns out the small flex wheels and nitrile rubber wrapped around a WCP roller work pretty well!
One of our highest priorities is the mid climb. I don’t want to slap a done sticker on this quite yet, but if we wanted to be finished right away with that we might as well be. We created an offseason climber for Whiteout our 2020 robot. This design was actually inspired by Spectrum’s offseason climber but I don’t know if they ever got theirs to work at competition. With our spin on the design, we were extremely successful. The robot climbed every match at THOR without fail and rocketed us to number one with a 2 second lift. The climber is too tall to be legal for this game, but if we lopped off the hook rods slightly, it would be legal and work.
Some details about this device…
It is a chain driven two stage elevator driven by two Falcon 500s (this we have found is overkill). Maybe Lance can post the ratio, this custom gearbox was his baby. This box worked better than I thought it would. We had our rookies work on it and there were certainly some egg shaped holes.
The small air piston and WCP ratchet brake did the trick here. We threaded a small rod, stuck it on a shifter piston, and pushed a screw through it into the pawl. For those designing a brake like this, make sure you put this on the first stage so you don’t need to fight additional torque!
The sliders are the magic bullet for us and I am sure a lot of teams are wondering how they will do some of these custom elevators/telescopes. We 3D printed our blocks. Yep. We are insane. So is the HP 3D printer we have access to through. We are using Nylon 14 and at first we had our suspicions about these but ultimately even if we replaced 5 of them a competition we would still be cheaper in plastic than machining these bad boys. We have yet to replace a single printed part on this device after two offseason competitions and an extremely successful run at both. (it is time to replace a few, but you can see them in the photos working quite well.
As for how we attached the chain? The chain is a continuous loop. We used a WCP chain tensioner with a 1/2" tube running through it, compressed by a 1/4" bolt through the bottom of the main stage (you can see the bolt in the photo below at half extension)
It isn’t the prettiest design out there, but it is simple, effective, and easy for us to use the limit distance function to create soft limits. It will most likely make a modified appearance with some upgrades on our 2022 robot.
Our shooter has also been somewhat copy pasted from what we know. Last season our 2021 robot Subzero was the highest performing robot in NC at the shooting challenges so we decided to take it and improve it. We began by widening it, and giving a couple of options for hole patterns based on the compression test we did earlier in the week. The result was something that was easy enough to slap together, and it taught many of our team members how to tap rods properly.
We used 1/4" lexan and cut these out on our little XCarve in the back.
The pulleys are 1.3:1 if I am not mistaken and we are running two falcons on each side.
The flywheels we picked are identical to Subzero, but we are using four instead of two to increase the mass of the flywheel. The 4" colsons have been great for us as flywheels!
The resemblance to our 2021 robot is obvious in our design and I saw the robot peeking over as though we were mocking it for being small. We will probably experiment with another “bearing stack turret” since it will only take us a few minutes to design one based off of Subzero. The programming team is working hard on using this robot to master pathfinding for auto runs since the robot is very similar in drive system!
Are the smiling? I think they are smiling. Our rookies are awesome! We had to put this one together a few times to get it right. A big win as the big shooter looks at it’s older brother undergoing some maintenance as we got ready to strap the finished product onto the earlier prototype.
We decided to try the middle compression, only about half an inch (maybe 3/4"). Most shooter prototypes yeet the ball so far there is no way those shots will go in on the real field. We dialed our falcons down to a modest 50% to try a bump fire into the high goal and met with success our first shot high at that setting. A 30% shot allowed us to scoot one into the low goal.
From the pad we ran into a very frustrating problem. Our ceiling has a huge HVAC duct right in the middle of our field and there are also roofing nails exposed that we believe WILL catch one of our game pieces one day. We believe a 65-70% shot will land in the high goal from the pad IF we add a mobile hood and scrape below our ceiling. We have a hood design for this on Subzero, but we really don’t want to add a hood if we can control the ball trajectory with just power/speed of the falcons. So far our release angle I believe settled out to be about 15 degrees for a nice gentle arc with mild backspin.
We will post some videos of our shooter and intake tomorrow and hopefully a ton of additional content as we enter Saturday!