The Robot in 3 Days Team Indiana tested a six wheel drive with pneumatic wheels and the rhino treads. In the videos below. The treads look like a much better option than the wheels. Is your team going with treads or wheels? Why?
6 Wheel Drive
Treads
My team is going with pneumatic wheels simply because we did not want to deal with the long lead time on treads.
Also, I don’t think pneumatic wheels on the kitbot frame are representative of their full capabilities, because the kitbot does not have much ground clearance, which contributed to it getting stuck in the moat.
My concern with tread is that the current offerings are essentially untested on the field. The long lead time is also a deal breaker. The last time I can recall seeing tank treads on an FRC field was in 2006 with Karthik’s triplets (perhaps I’ve missed a robot or two). But for the most part, most teams do not have experience with using them or maintaining them or dealing with their failure modes. Couple that with the long lead time of the Rhino treads, I know most teams aren’t going to be able to practice driving with them. It’s a scary situation all around.
It actually got stuck in the moat because the far side of the frame fell off the side of the field element! That’s why Charles picks it up and moves it to the middle.
There will be some lovely footage of it flying over the moat Dukes of Hazzard-style in the reveal video or uploaded afterwards!
Same reason, but we’re looking at COTS semi-pneumatics and making our own wheels more than pneumatic. Our goal is to have a drive platform crossing half of the defenses before the tread would be available so we can spend time on manipulators. An hour of web searches renewed our previous understanding that there aren’t any other COTS treads out there that looked both tough enough for FRC and affordable.
If I was looking to make my own treads, I would look at conveyor belting. Available at Mcmaster Carr or your local conveyor supply company.
Team 1619 has some nice resources on tank treads and they have used them for a while.
where do you source your belts?
Aside from ground clearance, does the Ri3D Indiana team say if those are 6" or 8" wheels? My very un-calibrated eye seems to think those are 6" wheels in the video. If that’s the case, consider that the 8" variety may provide better performance.
From what I see on their twitter their wheels see to be the 8" variety because of the oranges… but if you look at the holes along the side you can see that the wheels go across about 7.5 holes of length so 7.5 inches and the pneumatic wheels are just under 8" from my measurments.
Those are the 8" AM pneumatic wheels though that 8" is a nominal dimension and they measure out between 7.5" and 7.75" in the real world.
Another thing to note is that AM assembled that chassis with the wheels in the “long 8” wheel configuration" using the belts included in their 8" pneumatic wheel kit.
You can use the belts included in the 14u3 kit for the 6" wheel square configuration, put the wheels in those holes for a shorter wheelbase.
I believe that is what Snow Problem did and that is what we did at Team [Redacted]. That shorter wheel base causes the front of the robot to be higher when the front wheel has cleared the ramp and is hanging out in space. That helps get the front bottom corner on the frame over the rock wall. We did find that it hitting it at speed works better than trying to crawl over it.
any idea what these treads from brecoflex cost?
Expensive… I’ve heard $200-300 a piece is average.
Remember that if you use treads, an opponent can T-bone you and you won’t be able to move or turn. And it technically isn’t pinning because you aren’t trapped against a game element.
They also have this playlist of all the terrain obstacles. Some are tested with wheels and treads others are just treads.
Why wouldn’t you be able to move?
We have always purchased them from Brecoflex. They can get expensive, between 130-200 but this was a few years ago.
We used AT10-K13 Self-Tracking Belts. You have to pick one of the backings available. Lead time has always been around 3 weeks. Cheapest way to go is to buy their regular pulley stock and machine the K13 V-Groove on them for self tracking.
