Bumper Inspection Discrepency

[RMS11]

At Alamo, our bumpers passed inspection with flying colors and were even complemented by many inspectors for how effective they were. They are one single assembly that we slide over the top of our robot into slots in the frame.

At Peachtree, we were informed from the beginning that our bumpers were illegal. The butt joints created by the wood at the corners of the bumpers were ruled not legal. We reconsulted the rules and figured that under <R07> L, "Hard" parts of the BUMPER (i.e. plywood backing, fastening system, and clamping angles) may extend up to a maximum of 1" beyond the FRAME PERIMETER." made us legal.

The inspectors called FIRST headquarters, who said that our bumpers were illegal, as wooden backing may only extend the length of the horizontal projection. We spent the next few hours removing the bumper fabric, cutting off the butt joints with the reciprocating saw, installing angle brackets on the inside of the bumpers, and reassembling the fabric. It was annoying, to say the least, and made our bumpers much less attractive, much less structurally sound, and was just an overall pain. we were annoyed that they called this, yet allowed teams to pass who's bumpers dragged on the ground, were ziptied on, and even some without numbers on all sides. But ok, I do not fault the inspectors as the ruling came from FIRST headquarters.

I was just curious, have other regionals been calling teams on this? I just wanted to let other teams who built their bumpers like us to be prepared for this possible ruling. How does everyone else interpret this rule? We plan to remake our bumpers for North Carolina...

[EricH]

<R07-D> is what they probably were calling you on. That's the bumper segment length rule. The exception to <R07-D> is <R07-C>, soft stuff in the corner.

"Quick" solution for North Carolina: Wrap the pool noodles around the corners, but don't put wood into the corners. If anybody complains that that's illegal, point them straight to <R07-C>, where that method is explicitly allowed. Then use the frame attachments that you did before.

If they were passing teams that had blatantly obvious and relatively easy to fix bumper problems (ground clearance, numbers, and non-secure fastening methods), while enforcing a rule that's tough to enforce and tough to fix non-compliance, there's another problem there. All the rules are rules, not just the ones that you want to enforce.

[Gary Dillard]

I can't tell you about this year but if I understand what you are describing, they would be illegal this year for the same reason they were illegal last year.

If you check the Q&A's, if something is legal by one rule but illegal by another rule, then the more restrictive (illegal) rule takes precedence. In this case the 1 inch extension for R07 "L" may be OK, but the more restrictive Joints between BUMPER segments and the radial projections of corners must be filled with “soft” BUMPER materials. from R07 "C" takes precedence (emphasis mine).

[Tristan Lall]

Remember that for a completely-overlapped corner constructed to the theoretical maximum dimensions, the distance between the outermost vertex of the bumper backing and the nearest point on the frame perimeter is:

0.75 in × sqrt(2) = 1.061 in

Since this exceeds the 1 in clause of the rule, that construction is technically illegal.

In fact, the rule doesn't prohibit overlapping backing corners in general (by virtue of not mentioning them at all), it merely prohibits this degree of overlap. To confuse matters, it actually requires teams to fill the corners with soft materials—and this could be read to mean that the entire corner must be soft.

Additionally, the statement "wooden backing may only extend the length of the horizontal projection [of the frame perimeter]" is a bit dubious. The maximum length of a segment cannot exceed the "maximum horizontal dimension" (unclear whether that's a diagonal across the frame, or a side length), but this doesn't say anything about overlap. Further, although there is a requirement that "a full segment of BUMPER must be placed on each side of the corner", it's not clear whether that means the segment must begin at the vertex, or merely whether each side of the corner must be adjoined by such a segment.

[sdcantrell56]

As a mentor for the team in question, this ruling was beyond annoying and just added to the already generally poor inspector quality at the Peachtree regional. Our bumpers had pool noodles in the corner and did not have any hard surfaces sticking out. We merely created our bumper backing as one solid piece so that it would be robust and the simplest connection possible. Additionally this does fall within the rules as we use baltic birch sold nominally as 3/4" plywood but it is in reality 18mm thick.

[Jon Stratis]

Unfortunately, inspection discrepancy is almost the norm. Everyone does their best, but, as you see in the Q&A every year, the rules can be interpreted differently. Further, inspectors really only get a limited amount of time with each team, and can easily miss something. I can't count the number of times we've had an inspector at our second regional make us file some sharp edges the first inspector hadn't noticed, or other small items like that.

Personally, when we're going through the build season, I'm always trying to read the rules in their strictest possible interpretation to ensure we don't get hit with anything at inspection. It doesn't always work, but I can definitely say that it helps.

[jvriezen]

I've wondered about the reasoning behind that corner rule. I can plusible think of two reasons:

1) The case where a robot is hit hard right at the end of the bumper with the overhanging plywood and the plywood on that side pushing the adjacent side's plywood laterally, risking shearing off the attachment hardware.

2) If the bumper with the long plywood should happen to become detached at one end, but still secured at the other, and it gets tangled up with stuff, the bumper will act as a lever and potentially push the adjacent side board and shear off its mounting hardware.

Basically, I think its because they want the bumper segments (at least the hard parts) to remain independent and not 'react' with each other so that failure of one bumper doesn't cascade into potential failure of an adjacent bumper -- the above are specific cases of that.

I do know at least one team was cited for the same reason at Lake Superior Regional at least initially.

John Vriezen
Team 2530 "Inconceivable"
Mentor, Drive Coach, Inspector

[wouldwurker]

Having been intimately involved in bumpers over the past 4 seasons, I went back and checked previous manuals. Figure 8-4 was in the 2010 manual but is missing this year. They were very specific about this last year, but not this year.

[Kevin Sevcik]

I think this probably bit a fair number of teams coming out of Alamo. I know it also bit 3103, Iron Plaid, when they were inspected at Lone Star. They had the exact same butted construction pass at Alamo, and it too was ruled illegal in Week 3, but at Lone Star. Which is frustrating because I help those girls out and I posed this EXACT question to the GDC and got what I THOUGHT was a go ahead for it. I'm not really sure how else I was supposed to take this exchange on the Q&A:

Originally Posted by 2011FRC0057

Single piece bumpers
Is it permissible to build a set of bumpers such that they form a single solid framework that can be lifted on/off the robot? Two proposed construction methods would be:
1. Build a rectangular frame out of 5" tall, 3/4" thick plywood. The ends would be butted and screwed/glued together. Thus, there would be 3/4" of "unsupported" bumper at each corner sticking outside of the frame perimeter.
2. Build a rectangular frame out of 5" tall, 3/4" thick plywood. Leave the corners empty, and attach the pieces at the corners with angle brackets. This removes the 3/4" of unsupported bumper, but adds some angle brackets to the bumpers.
Option 1 may or may not comply with R07-K and L. Compliance with K hinges on whether a <8" unsupported section of bumper must be supported on both sides by the frame perimeter. Compliance with L depends on if the 1" extension is strictly perpendicular to each segment of the frame perimeter, or if it's more a 1" offset outside the frame perimeter polygon.

Originally Posted by GDC

Re: Single piece bumpers
The purpose of this forum is to clarify rules and answer questions about intent behind rules. We will not provide specific answers regarding how rules are administered.
Generally speaking, there are no rules that prohibit one-piece BUMPER ASSEMBLIES.

I ended up assuming the positive second paragraph was the answer. Apparently I should instead have stuck with the non-answer first paragraph and told Iron Plaid that the none of the Q&A answers actually have any bearing whatsoever on how the rules are actually administered at competition. And thus.... something.

Which is sort of the problem with some of the GDC's non-answers to questions that should really be fairly easy for them to answer. Especially because there apparently IS an answer from FIRST HQ on the legality of Option 1 there.

You'd think they might have told me that two months ago when I asked.

Yes, I know the GDC doesn't want to get bogged down with making 200 specific rulings on 200 specific design questions that are actually covered by the rules. That's why I went to all the trouble of laying out my reasoning and interpretation of R07-K and R07-L in the question. I did, in fact, want them to clarify one or both of those so we could all understand the intent and move on with our lives. That they completely failed to do so while declaring that was what they're there for was somewhat less that impressive. That someone up there apparently DID have the specific clarification I was hunting for is just a bit annoying.

I like to think that all my questions of the GDC have a purpose and point to specific areas of the rules in need of clarification, but they clearly don't agree. So, if anyone with inside information is reading this, I'd really like to know exactly how I AM supposed to word my questions so that they'll get an actual response instead of the form letter "we don't rule on specific designs". If I have to format them all in abstract terms with no reference to any proposed design, I'm willing to do so. I think it makes the whole thing that much harder to understand, but I'll do it just to get some reliable answers out of them.

[Mike Betts]

Originally Posted by wouldwurker

Having been intimately involved in bumpers over the past 4 seasons, I went back and checked previous manuals. Figure 8-4 was in the 2010 manual but is missing this year. They were very specific about this last year, but not this year.

For the reasons noted (Figure 8-4) and my previous position on the matter (see my December post) and the GDC's position that a one piece bumper is OK, I directed my team to miter the wood corners as well.

At Florida, our LRI cited <R07-D> and wood in the corner was prohibited.

I blame myself rather than the system. I should have posted to the GDC on this issue. Sometimes you think you are right and don't bother to ask...

Oh well...

[sdcantrell56]

Originally Posted by Mike Betts

For the reasons noted (Figure 8-4) and my previous position on the matter (see my December post) and the GDC's position that a one piece bumper is OK, I directed my team to miter the wood corners as well.

At Florida, our LRI cited <R07-D> and wood in the corner was prohibited.

I blame myself rather than the system. I should have posted to the GDC on this issue. Sometimes you think you are right and don't bother to ask...

Oh well...

The problem is that the GDC has not officially ruled on this and it was just up to there discretion once we got to our second regional to say that we were illegal even though there was no performance gain or anything from our system. Functionally our bumper is 100% identical to similar bumpers constructed with angle aluminum in the corners.

[Andrew Y.]

My biggest concern with the ruling was less with the rule itself but more with what was allowed. We had inspectors come into our pits even before we began the inspection phase and began looking at our robot and bumpers. From listening to the conversation...most of the inspectors seemed to think the bumpers were fine but ONE inspector decided they wern't and had FIRST headquarters called and thats when we got the news that the bumpers were in fact illegal. So we argues and showed R07L but it was still deemed illegal by FIRST headquarts. So whatever....we fixed the bumpers and were on our way.


What REALLY annoyed the living crap out of me was seeing teams with dragging bumpers...HUGE V gaps in all corners, no team numbers, fabric that was hanging off, and viptied to the frame of their robots. When i brought this issue up with the inspectors i was told "we needed to get teams out there and passed inspection so we let it slide" WHAT THE HECK IS THAT?! so a team that is prepared is more likely to be scrutinized than teams that didnt?

what i learned from this....inspect late...better chance they will let you slide.

[Kevin Sevcik]

Originally Posted by Mike Betts

For the reasons noted (Figure 8-4) and my previous position on the matter (see my December post) and the GDC's position that a one piece bumper is OK, I directed my team to miter the wood corners as well.

At Florida, our LRI cited <R07-D> and wood in the corner was prohibited.

I blame myself rather than the system. I should have posted to the GDC on this issue. Sometimes you think you are right and don't bother to ask...

Oh well...

Lucky for me I did ask the GDC specifically about wood in the corner and got back a vaguely affirmative answer, so I can totally blame the system. I'll only fault myself for not following up and pressing for an actual answer from them. I know that's sometimes necessary and I should've realized this was one of those cases.

[Tristan Lall]

Originally Posted by sdcantrell56

As a mentor for the team in question, this ruling was beyond annoying and just added to the already generally poor inspector quality at the Peachtree regional.

Fundamentally, if the inspectors do something that's really annoying, but in line with the rules, how should fault be apportioned?

Undoubtedly there's an element of inspector's discretion involved—and the rationale for applying that discretion varies greatly from inspector to inspector. And maybe the team ought to have read the rules a little more closely. But in my view, the majority of the responsibility has to lie with FIRST: they make the rules that everyone needs to follow, and when they err, everyone feels the repercussions. Most teams are making a genuine effort to comply, and most inspectors are making a genuine effort to bring teams into compliance (without punishing them, if at all feasible). Obviously FIRST is trying hard too, but it's their competition and therefore their ultimate responsibility.

Originally Posted by Andrew Y.

My biggest concern with the ruling was less with the rule itself but more with what was allowed. We had inspectors come into our pits even before we began the inspection phase and began looking at our robot and bumpers. From listening to the conversation...most of the inspectors seemed to think the bumpers were fine but ONE inspector decided they wern't and had FIRST headquarters called and thats when we got the news that the bumpers were in fact illegal. So we argues and showed R07L but it was still deemed illegal by FIRST headquarts.

Was the one the lead inspector? It's part of their job description to determine whether FIRST needs to be consulted—it's not exactly a vote.

Originally Posted by Andrew Y.

What REALLY annoyed the living crap out of me was seeing teams with dragging bumpers...HUGE V gaps in all corners, no team numbers, fabric that was hanging off, and viptied to the frame of their robots. When i brought this issue up with the inspectors i was told "we needed to get teams out there and passed inspection so we let it slide" WHAT THE HECK IS THAT?! so a team that is prepared is more likely to be scrutinized than teams that didnt?

I suspect that attitude is more prevalent when dealing with bumpers than with other rules. Everybody hates bumpers to some degree (except maybe the GDC?). At any given event, if there's one place you're most likely to see deviations slipping through, it's the bumpers. It's not ideal, but neither is the bumper rule.

Also, as we've seen here (yet again) this problem has a cascade effect. The team then attends another event, where the enforcement ends up being a bit more strict, and it's a difficult situation all around.

(When you compare the difficulties in complying with the entire bumper specifications from any of the past several years to the meagre benefits derived from the bumpers, you find that bumpers are usually a dreadful value proposition. It's no wonder people are so contemptuous of that particular rule.)

Originally Posted by Andrew Y.

what i learned from this....inspect late...better chance they will let you slide.

Also a better chance they'll make you fix something, and you'll miss your first match as a result. (Remember, don't even show up with a human player in that case; your alliance will kill you.) Depending on your team's level of risk aversion, that might not be a sensible game to play.

[MrForbes]

Originally Posted by Tristan Lall

(When you compare the difficulties in complying with the entire bumper specifications from any of the past several years to the meagre benefits derived from the bumpers, you find that bumpers are usually a dreadful value proposition. It's no wonder people are so contemptuous of that particular rule.)

I have no problem with bumpers. They are kind of a pain to make, but they do their job and the red/blue/number thing makes it so much easier to figure out which robot is which, and which alliance it's on.

We've never had any inspection issues with them at all. We do our best to figure out just what the GDC really wants (it is very simple as I see it), we don't try to do anything fancy, and it works out fine.