Brainstorm: Improving the FRC bumper rules

[Tristan Lall]

When this came up last year, here's what I said:

Originally Posted by Tristan Lall

The simplest and most productive way to fix this is to specify a reference bumper configuration that is by definition legal, and ask inspectors to qualitatively evaluate teams' actual configurations in comparison to this standard. As long as the bumper meets some very basic dimensional and functional criteria (e.g. bounding size, weight and tactile qualities), there's little value in making a regulatory distinction between things like Ø2.5 in pool noodles and Ø2.0 in pool noodles—because realistically, they both do almost the same thing. Now of course, this makes the rule subjective rather than objective, and will mean that we'll be depending on the inspectors to say "close enough", rather than follow precise criteria. In this case, I think that's fine, because bumpers have one fundamental purpose: to reduce damage to robots. If we see a mix of robots that are each—according to the inspectors best guesses—between 75% and 200% effective, relative to the reference design, that's not a problem. And if so, who really cares whether they used foam rubber bricks, pool noodles or hippopotamus tenderloins? Also, teams can't complain much about subjectivity if they're offered a perfectly good reference design to emulate, and choose not to—the reference design should be teams' first choice, unless they have a good reason to deviate.

I think that all continues to hold true.

Additionally, I would support the idea that bumpers be made optional again, as long as it's clear that robots running without them would not draw more penalties against the opponent (despite being more likely to be damaged), and that they would have to identify themselves in an equivalent way (e.g. coloured, numbered placards in the bumper zone).

Mandatory bumpers do have one big advantage: they save teams that build the robot to the full 38 in × 28 in limits from huge trouble when the frame twists, or their tolerances are off. This can be obviated with a simple note in the rules: "Build your robot smaller than the maximum limits of size to account for manufacturing tolerances and distortion due to damage suffered during gameplay. As a rule of thumb, you should consider building the robot at least 1 in smaller than each limit."

Things like supporting the entire backing of the bumper are not helpful. If a bumper breaks, who cares? It's a bumper. Either fix it with some sort of gusset, or cut it and call it two bumpers. The rules should be written to permit a simple, effective resolution to a broken bumper, instead of imposing a basically-worthless constraint on everyone—which, due to the phrasing, affects teams even if there's no reasonable chance that their bumpers will break. During inspections at three events, I saw two teams with essentially unsupported bumpers along two sides (including one at the Championship...). They were forced to add structure to support the backing of their bumpers—even though, in all likelihood, the bumper backing itself was much stronger than the structure. By contrast, I saw more than a dozen teams that had small gaps behind their bumpers which were technically illegal, but which posed no real problem from an engineering perspective. And yet, the rule is clear: they must support the entire length of each bumper with the robot's structure or frame. So mounting points were adjusted, or bumpers shimmed. This wasted a lot of time, both for teams and inspectors. But basically: this constraint is useless, and even counterproductive—either get rid of it, or write in a clause that specifically allows inspectors to override it based on their engineering judgment.

Bumper colours were very helpful for identifying alliances, but quite the opposite for identifying teams. With the location of the bumpers this year, and the fact that many robots were low, it meant that a lot of robots were hard to identify from a distance or on the webcast videos. While in the past, unique bumpers were easy ways to identify robots, this year, everyone had to rely more closely upon the team numbers (which are quite invisible in many webcasts). I'd be quite happy to see the rules allow the bumpers to be any colour, except for an inset patch (at least 12 in long) corresponding to the alliance colour, and containing the team numbers in white.

Bumpers should be required to be removable in 20 s per bumper segment. No exceptions. This isn't rocket science, but because the rules suggest threaded fasteners, teams tend to go with complicated arrangements that require the insertion of hand tools into tight spaces. Teams will rapidly discover the existence of various spring pins if forced to design bumpers to be removed quickly.

Finally, though it's not technically part of the bumper rule, the frame perimeter rule was a significant annoyance. Hopefully there won't be any reason to need this next year—but if it does come back, tighten the definition.

[AdamHeard]

Originally Posted by Tristan Lall

Things like supporting the entire backing of the bumper are not helpful. If a bumper breaks, who cares? It's a bumper. Either fix it with some sort of gusset, or cut it and call it two bumpers. The rules should be written to permit a simple, effective resolution to a broken bumper, instead of imposing a basically-worthless constraint on everyone—which, due to the phrasing, affects teams even if there's no reasonable chance that their bumpers will break. During inspections at three events, I saw two teams with essentially unsupported bumpers along two sides (including one at the Championship...). They were forced to add structure to support the backing of their bumpers—even though, in all likelihood, the bumper backing itself was much stronger than the structure. By contrast, I saw more than a dozen teams that had small gaps behind their bumpers which were technically illegal, but which posed no real problem from an engineering perspective. And yet, the rule is clear: they must support the entire length of each bumper with the robot's structure or frame. So mounting points were adjusted, or bumpers shimmed. This wasted a lot of time, both for teams and inspectors. But basically: this constraint is useless, and even counterproductive—either get rid of it, or write in a clause that specifically allows inspectors to override it based on their engineering judgment.

I agree.

We usually run the west coast drive, a system that is extremely minimal and elegant in construction. The fact that we had to do this in 2009 to fully support the bumpers is silly to me, we could've supported them at a few places and be done with it. That doubled the amount of welding and parts in our frame, along with adding a pound of useless weight and making the frame ugly.

It's a little insulting for FIRST to say, hey, we don't trust you to build a frame right, so here are bumpers. I can live with that, but when FIRST says we further don't trust you enough to put bumpers on there without them breaking, so you MUST support them the entire length, that's just ridiculous.

[Tetraman]

Do the bumpers need to be as thick as they are? What if we chopped down their outward extension?

I always liked the bumpers but thought it was rather clunky and needs some refinement. Not sure what else to say though.

[GaryVoshol]

I really liked the red/blue colors this year. It made telling alliances apart very easy, even moreso than last year when you might have a red trailer pulled by a blue robot. I understand the team image issues, but perhaps that can be addressed in another manner.

I didn't like most of the removable bumper covers I saw - they looked shoddy. Add to that some very amateurish numbering methods. C'mon, let's try to make these machines look like the high-tech and high-class robots that they (usually) are.

I agree that the rules are too complex, without getting to what the GDC really wants. When too many smart teams can misinterpret the rules and show up with defective bumpers, the rules aren't written clearly enough.

I'm not sure why the frame perimeter cannot have concavities. As long as each section of the frame is at least 6" long and protected by an adequate bumper, why can't there be a pocket?

As for the bolthead and rivet rule, don't get me started ...

[nikeairmancurry]

Originally Posted by GaryVoshol

I really liked the red/blue colors this year. It made telling alliances apart very easy, even moreso than last year when you might have a red trailer pulled by a blue robot. I understand the team image issues, but perhaps that can be addressed in another manner.

I didn't like most of the removable bumper covers I saw - they looked shoddy. Add to that some very amateurish numbering methods. C'mon, let's try to make these machines look like the high-tech and high-class robots that they (usually) are.

I agree that the rules are too complex, without getting to what the GDC really wants. When too many smart teams can misinterpret the rules and show up with defective bumpers, the rules aren't written clearly enough.

I'm not sure why the frame perimeter cannot have concavities. As long as each section of the frame is at least 6" long and protected by an adequate bumper, why can't there be a pocket?

As for the bolthead and rivet rule, don't get me started ...

My teams main issue with the bumper rules this year. Our design had two concavities, those such allowed the ball to roll under the robot without going the 3 inches under the robot. It was a genius idea on our part, and the refs at our first event thought it was awesome.

When we were asked to change the design, our main issue was, what advantage did we gain by doing this? We were never given an answer by the GDC or and Inspector, but we did comply and change the design in about two hours at the Troy District Event.

[pfreivald]

Originally Posted by nikeairmancurry

When we were asked to change the design, our main issue was, what advantage did we gain by doing this? We were never given an answer by the GDC or and Inspector, but we did comply and change the design in about two hours at the Troy District Event.

I have no problem with the answer to many rules questions being, "Because we said so."

I usually revise that when my students ask that question of me. I say, "To make it harder."