The spread of pinching rollers this year

[AdamHeard]

I know it isn't that uncommon for teams to change their design once they've seen other teams, but I feel like this happened moreso this year with the pinching roller intake than any other mechanism any other year.

To be clear, I'm referring to dual horizontal rollers, one above the ball below. In most applications the bottom one is fixed so it can't rotate, and the top has some sort of clutch or current control.

I'm curious to hear who had the design idea initially, and who added it later, and if so, who did they copy/get inspiration from?

I guess it's common knowledge that "Team IFI", 148, 217, 254, 968, 1114 and 2056 all had the design at ship time.

We added ours a week or so after ship mostly from inspiration from 148's video.

I know 971 added theirs after ship but before the San Jose regional and was inspired by 254.

I know 294 added theirs after San Diego but before Los Angeles from us, inspired by 148.

It'd be interesting to track the entire spread of it.

[EricVanWyk]

I was convinced that this sort of setup was illegal: Thought of it at kick-off and dismissed it almost immediately.

Later, I thought it would be legal only if it was somehow cantilevered so the ball was guaranteed to be contacting the ground.

Later, I saw that refs weren't calling these sorts of things and we joined the crowd.

[AdamHeard]

Originally Posted by EricVanWyk

Later, I saw that refs weren't calling these sorts of things and we joined the crowd.

Calling these sorts of things?

If the ball stayed on the ground it was legal.

[Tom Bottiglieri]

Originally Posted by AdamHeard

If the ball stayed on the ground it was legal.

I can't speak for the other teams, but I know 254's and 971's passed the piece of paper test. (Slide a piece of paper under the ball to see if the ball is contacting the ground.)

[Matt Howard]

Originally Posted by AdamHeard

Calling these sorts of things?

If the ball stayed on the ground it was legal.

For many of these machines though, the balls DIDN'T stay on the ground. There were instances at regionals as well as at the World Championship where this was being inspected with a ball and a playing card.

[Aren_Hill]

We adapted to having a pinch roller, and the simplest way to go about it was put the thing on a hinge...easy solution ball stays on ground.

[BJT]

We upgraded ours on thursday at the northstar regional. due to the way our kicker was designed I couldn't make it as wide as I would have liked but it still worked great. We decided to change from our vac after seeing 148's video.
Our ball rode on the floor quite hard, but it was pinched in so hard it stayed there quite well.

[apalrd]

We bagged the robot with a higher-speed top roller and played like this at Kettering. We then looked at several other robot's up close, and built a pincher-roller for Troy using the practice robot as a guide. This taught us two things:
1. pincher rollers are waaay better
2. the practice bot is really far off of design specs

Ours was a floating design, so the entire assembly was a four-bar linkage. The two horizontal bars supported the bottom plate and top roller, one vertical "bar" was the chassis, and another held the two pieces a fixed distance apart. Using bungee, we sprung it down to avoid carrying penalties, and put some little wheels on it so metal never touches the ground. We had an issue with carrying penalties at Troy, so we fixed it in software and haven't had problems since.

We actually had an interesting problem with ours: It had such a good grip we could no longer kick more then about 3 feet. So we fixed it in software and can now kick the full 33 feet (+ a few more) it could with the old roller.

We carefully tuned the depth of the top roller and bottom plate, as well as the distance between the two, to get the most grip while not allowing a piece of paper to go under the ball. Software helps with this: If the roller is allowed to run continuously, it will gradually suck the ball in more, and carry it. If you just kill the roller, then it will loose the ball. We implemented a duty-cycle based roller kill to pulse the roller when holding a ball (determined by a broken-beam sensor), and to continuously run the roller when going backwards (both joysticks are positive, reverse) to prevent loosing the ball. Timing this was tuned to 5 iterations on for a 20 iteration cycle.

[Tom Line]

Originally Posted by apalrd

We bagged the robot with a higher-speed top roller and played like this at Kettering. We then looked at several other robot's up close, and built a pincher-roller for Troy using the practice robot as a guide. This taught us two things:
1. pincher rollers are waaay better
2. the practice bot is really far off of design specs

Ours was a floating design, so the entire assembly was a four-bar linkage. The two horizontal bars supported the bottom plate and top roller, one vertical "bar" was the chassis, and another held the two pieces a fixed distance apart. Using bungee, we sprung it down to avoid carrying penalties, and put some little wheels on it so metal never touches the ground. We had an issue with carrying penalties at Troy, so we fixed it in software and haven't had problems since.

We actually had an interesting problem with ours: It had such a good grip we could no longer kick more then about 3 feet. So we fixed it in software and can now kick the full 33 feet (+ a few more) it could with the old roller.

We carefully tuned the depth of the top roller and bottom plate, as well as the distance between the two, to get the most grip while not allowing a piece of paper to go under the ball. Software helps with this: If the roller is allowed to run continuously, it will gradually suck the ball in more, and carry it. If you just kill the roller, then it will loose the ball. We implemented a duty-cycle based roller kill to pulse the roller when holding a ball (determined by a broken-beam sensor), and to continuously run the roller when going backwards (both joysticks are positive, reverse) to prevent loosing the ball. Timing this was tuned to 5 iterations on for a 20 iteration cycle.

That's pretty funny - we found the exact same thing. We had this design installed about a week before ship but were tuning it right up to the day we sent the robot out. It took us a while to get the hang of setting it up so it stayed on the ground, but once we had a system of setting it up it worked well.

The first iteration didn't allow us to kick very far either - we adjusted our backstop and bottom bar to get just the right amount of grab.

We also realized that on our practice bot we offset the middle wheels down. On the comp we offset the front and rear wheels up. Oops.

We used a simple vacuum cleaner belt to drive the roller - once the ball hit the backstop the belt slipped on the upper roller so the window motor didn't stall. Ours didn't float, but we did make sure it kept the ball on the floor all the time. We never changed that belt once. $2.49 from Ace Hardware.

[sanddrag]

Originally Posted by EricVanWyk

Later, I saw that refs weren't calling these sorts of things and we joined the crowd.

Weeks were spent in the iterative design process to ensure "these sorts of things" were physically impossible with the 254/968 pinch roller design. The mechanism was on a free pivot, such that the entire robot could lift from the floor by a significant amount (more than 1" I believe) and the ball remained in contact with the ground, such that a piece of paper could not be slid beneath it. For added security, at Long Beach, 968 added springs to actually push the ball into the ground with some force, beyond the weight of itself and the mechanism. I don't feel that any team with such a mechanism got away with a certain "way" referees were calling anything.

[sdcantrell56]

I know we made the change after peachtree and seeing how ineffective the vacuum was compared to the awesome pinching roller of 148/217. We went into peachtree knowing we would be changing the design and ended up showing up to champs with a pinching roller with the whole assembly on linear bearings to allow ~1" of vertical play so that the ball always stayed in contact with the floor during normal play.

The roller worked incredibly well and allowed us to really play to our full potential once we worked all the bugs out about halfway through friday of champs.

Thanks 148/217 for posting the video and answering questions about the design. Both programs are quite inspiring in there dominating designs.

[Chris is me]

Originally Posted by sanddrag

Weeks were spent in the iterative design process to ensure "these sorts of things" were physically impossible with the 254/968 pinch roller design. The mechanism was on a free pivot, such that the entire robot could lift from the floor by a significant amount (more than 1" I believe) and the ball remained in contact with the ground, such that a piece of paper could not be slid beneath it. For added security, at Long Beach, 968 added springs to actually push the ball into the ground with some force, beyond the weight of itself and the mechanism. I don't feel that any team with such a mechanism got away with a certain "way" referees were calling anything.

I was under the impression that 233 had a mechanism that oh so slightly lifted balls, and that caused them to miss elims at Florida.

I doubt refs ignored this when I've read posts about how teams were pulled to practice fields to prove balls stayed on the ground.

[Peter Matteson]

177 based our design on 1073 after we saw it a BAE as mentioned in our thank-yous thread. We designed our roller system to pass the piece of paper mentioned by others to be certain it was legal.

Edit:
I forgot to mention we had the clutch on our original possesor about a week before scrimmage on our original design. It was our own design using laser cut friction discs we custom made to work with our hex shaft.

[Enigma's puzzle]

2075 came up with this design on there own, and we actually got a lot of people gawking it on the practice field at Kettering. but instead of the solid top bad we used a 1/2 inch urethane cord and a piece of aluminum angle along the ground. It had the ideal coefficient of friction, as found by accident. It slipped when it needed and rolled the ball when going backwards and it also contoured to the ball to center it. Too bad we had a software issue that kept us immobile all but 2 and a half matches.

[EricVanWyk]

I realize that my initial post sounds a lot like I condoned cheating. That was not my intention. Our setup most certainly kept the ball in contact with the ground.

My intention was to indicate that I had assumed that the refs would be erring on the side of declaring legal mechanisms to be illegal, and it would therefore be unlikely to be worth the risk.