We finally got our robot working in prototype form. We need to make things a little more substantial…watch the video and see why 
What material is the arm?
And nice inside-of-tube grabber 
Arm is 2" abs sewer pipe, with an extension of 1.5" abs at the end which slides out about 18" at the start of the match (gravity powered). We still need to play with the geometry, I dont know if it’ll reach the floor where we want and also score the top goal. And fit that pesky 84" cylinder.
i hope you have better luck with the grabber than my former team did on 07. they used an identical design, and it always was getting hung up on the “foot”. it was mostly useless. granted, the feet were much bigger in 07 but getting hung up after hanging may be an issue to be aware of.
otherwise, good work… your team likes to make a lot of videos i see…
How much have you played with the geometry of the gripper fingers and the extension length? From the only two I got to see from 07, 25’s had a really solid grip on the tubes with what seemed like only two direct contact points. Ours OTOH had the fingers wrap around the tubes. There might be some type of uniform design that’ll work for all 3 tubes.
Hope it helps with more ideas for the gripper!
Good luck ya NERDS 
Right you are!:yikes:
…and very well I might add.
Interesting prototype!
Looks like 1726 and 2791’s bots will look VERY similar this year… but that inside gripper is definitely a different direction than we took. We liked how both pinch claws and roller claws could just “drive into” a tube to grab, while the inside gripper would need to be carefully placed inside a tube to grab.
Have you guys done any prototyping with regards speed of grab? If it turns out we’re dead wrong it’s not too late to change direction!
We have, turns out if you can drive with the grabber just above the tube and then bring it down and expand it you can get a good grip in less than 2 seconds. Of course you can also lower it into the center of the tube and then start driving away as you expand it and then its down to about a second. It was also a lot easier to align than anticipated when we mounted the grabber to an old 6 wheel WCD bot, which could be made even easier with a swerve drive…
That being said, I think in the end it’ll come down more to execution of design rather than which direction you took. Since you already have many iterations of the pinch claw/roller claw concepts, statistically speaking you are more likely to execute a pinch/roller claw well than to execute an inside expander well. So in this case it seems like there are no ‘right’ or ‘wrong’ directions, just ones that you are more or less familiar with.
My concern is having to consciously go “okay, we’re next to a tube, stop, lower, grab, up” rather than juts driving forward and havign the tube slide along with your arm.
I highly doubt we’ll adapt the design but I’d love to see it implemented successfully.
Well then you would love to see this!
Why even bother gripping, when you can take elevator a bit more literaly…
http://dl.dropbox.com/u/6865197/Code%20Red/Car.jpg
Our gripper travels on an elevator similar to the one in the OP, but it has two sides, for extra support!
Chris, the idea is that we drive into the tube, scoot it along the floor, and drop the claw into it and pop it open and lift the arm. The pointed claw when it’s “retracted” is a small triangle fitting into a big hole, so aim is not very critical at all.
We are doing the same thing. We designed our inside gripper (prototype here) to move down to the “grip” position so that is was inside all three shapes. No slowing down is necessary. Drive up to it, Push it and pick up.
Nice video 
This is exactly how I was imagining the pick up going. If it works right, all you need to do is drop the arm down, then you can open the claw and raise the arm on the way to the goal, drastically lowering the amount of work required to take control of the tube. In fact, that just makes one motion necessary, which puts the inside grab on par with a normal pinch type claw.
A few things to keep in mind this year:
- in 2007 you could shape your bumpers to help position the tubes.
- The target holes are smaller than they were in 2007
- In order for you to get the most out of your robot, you have to make sure your drivers have enough time to get proficient with the pick-up.practice, practice, practice!
Is your cylinder mounted between the two expanders?
Yes, on the side of the pivot opposite the tube pickup, so a closed piston opens the claw. There are also stoppers (screws) in the PVC that align the claw when closed.
What are the claws made of? I made mine out of PVC, but yours seem like flat pieces, how do they pivot?
The “fingers” in the video are 1/4" plywood taped with blue masking tape to prevent splinters. We’re working on building new ones from Lexan and using top and bottom fingers on each side, separated by spacers…