Welcome to the reveal of our worlds robot!
This robot is more or less just another meta bot, though it didn’t start that way. Originally we were attempting to score all 8 rings on the tall goal with this complicated deploying lift, loaded by pivoting needles by our conveyor, as seen in this test:
The actual loading of the rings ended up working very well, and we later got the deploy working consistently as well. The problems arose when trying to score the rings on the branches, because the goal had a tendency to lean in an arbitrary direction, shifting the branches by a large amount, which made scoring rings on them incredibly difficult to do on the ground, and the bendiness of the platform made it outright impossible when parked, which was the main goal. So with very little time left, we abandoned the idea. It just proved too problematic to justify spending the few weeks we had left before worlds on it.
But the core robot was also designed with this possibility in mind, which is why it’s a perfectly good meta bot without the tall goal. And there are a few things on this bot that make it different from most.
We chose a ratio of 400 rpm on 3.25" wheels for this bot, a considerable increase from the 360 rpm we had been running on the last robot. With the new sized gears, 400 rpm becomes a super easy and convenient ratio for 3.25" wheels, by driving 72t gears with 48t gears. But vex only sells these gears in high strength form, with inconvenient flanges that makes any screw heads stick out. So to slim down the drive, we used a belt sander to thin out the gears, and then drilled countersinks in the flanges where we mounted screws, so that we could fit them in a 3 hole wide gap, rather than a 4 wide one.
We also used custom traction middle wheels again, this time with a more refined approach.
Here's how we made them
step 1. sand down a 3.25" traction wheel so that the tire is perfectly round and the diameter is a good bit smaller than 3.25".
step 2. cut up a flex wheel by removing the spokes, and then thin the width of it down to 0.75", so that it is the same thickness as the 3.25" traction wheel.
step 3. wrap it around the traction wheel
step 4. cut out some polycarb discs that are larger in diameter than the 3.25" traction wheel, but smaller than the flex wheel tire. Screw these on either side of the wheel to retain the tire and keep it from slipping off.
this is a much cleaner and more even way to do it than the monstrosity I had previously been using.
not much else to say about the drive, it doesn’t have anything else unusual about it.
pretty much exactly the same as our last conveyor, which is to say extremely standard. The hood we used for the ring deposit is interesting though, it uses some 2.75" traction wheel tires to create a compliant arc of rubber for the rings to deflect off of. We found it works very well for us, though it’s by no means any better than what everyone else is doing.
Front clamp is pretty similar to our last, except the cylinder has been mounted in a nicer spot, better center of gravity, whatever, easy access.
It’s still a locking clamp, so once grabbed goals physically cannot be forcibly removed from the clamp, unless the clamp itself gets bent or destroyed in some way.
The rear clamp is also pretty much the same as on our last bot, but we added an additional cylinder to the tilter, because that was what ran out of air first on our last bot and we wanted this one to last just a bit longer.
The wing was something we added very recently, and it functions as just a multi-purpose utility tool. It’s good at righting tipped goals, snagging goals and dragging them, both in goal rush and during matches if I see an opportunity. And it can also help dislodge and goals that might get stuck under a platform. Didn’t really see any good reason not to have it, so that’s why it’s there.
this is probably the most unique part of this robot. In the reveal there are some little 4 bars that press a rubber bumper into the ground, but since recording we’ve changed the method of braking. Now it’s basically just some c channel that pushes on the tops of our traction wheels while active. This is enough to practically immobilize the robot, and has a few good uses.
The first use is for parking, because while on the platform, if we activate the brakes, we cannot fall off. Which means we can comfortably part at any point in the match without needing to worry about an opponent tipping the platform and causing us to slide off.
Another use is for tugging battles. If we get engaged in a tug between us and an opponent, we can activate the brakes to prevent the goal from moving anywhere without straining the drive motors at all. If this goal is on our side of the field, it doesn’t make any sense for an opponent to even attempt to drag us across, and they will either give up, or waste their time and drive power trying. And if the goal is on our opponents side, we can activate the brake, and if they keep pulling, they will eventually burn out their drive and then we can just pull them across. If they stop pulling but remain clamped, we can take that opportunity to quickly lurch backwards until the realize and start pulling again, and then we activate the brakes again. This way, we should be able to creep across the field bit by bit, forcing an opponent to give up on keeping the goal, or tire out their drive trying. I’m excited to see how well it works in practice at worlds.
You probably notice that we have no tall goal mech at all, where our last bot had a 3 preload one. This was due to a number of factors, the primary ones being that we didn’t think external preload scorers to be as viable anymore after the protected time change, and we didn’t think it was worth spending our limited time on compared to the brakes. I am sad to see that part of our strategy go though, because it really was my favorite part of our last bot.
This is also our last competing robot, as 99999v is an all-senior team. We’ve had an amazing experience in this program, and vrc has become a core part of my life over the last 6 years I’ve done it. I may not be competing after this year, but I aim to continue working as a part of this community to educate and assist people.
Speaking of which, none of what I have done since turning point would have been possible without the amazing people at SCA, who have been instrumental in my growth and development as a competitor. If I can take away one thing from vex, it’s that yes, the absolute best way to improve at something is to associate with people who are better at it than you.
Anyways, I hope you enjoy the video, and good luck to everyone going to worlds! be sure to swing by my pit (which will probably be tucked away in some far-flung corner).