1/2" gap in bumpers, is this acceptable?
 

We have assembled our robot bumpers on our rectangular robot. The front and back bumpers are as wide as the robot. The left and right side foam extends so that it is flush with the outside edge of the front and rear bumpers. This has created a 1/2" gap between the side bumpers and the front/rear bumpers. (Caused by the plywood backing.)

Do we have a potential problem passing inspection? We think we met the rule for complete coverage, but I don't want to be scrounging pool noodles during our Week 1 competition in Rochester.

Re: 1/2" gap in bumpers, is this acceptable?
 

This will not be acceptable at inspection.
You will have to fill that area with pool noodle to meet the rule intent.
I suggest that you cut the noodles at the end of the wood and then add a cut section of noodle there on end as the rules allow. When you re-wrap you should no-longer have gap.

Re: 1/2" gap in bumpers, is this acceptable?
 

Interesting question... my first response was "no way could that be a problem". From the photo the bumpers look sturdy, safe, and fully capable of fulfilling the role of being a bumper, and the 1/2" gap is insignificant to their overall purpose.

But R07-L and the related diagram 8-2, specify that the "corners must be filled".

So yeah... you could have a problem. Thanks for asking the question... we haven't built our bumpers yet, so we'll pay attention to this when we put them together this year. I don't think its likely to be a big problem from a practical point of view (I doubt many inspectors would call it... but they could), but given that you've got two weeks to get the bumpers up to spec right now, that's probably more fun than doing it in two hours on a Thursday morning.

Jason

Re: 1/2" gap in bumpers, is this acceptable?
 

That gap seems like the amount of space a somewhat flexible bumper could easily unintentionally leave if slightly jolted or something. Or, to be more clear, I'm pretty sure I've seen robots pass inspection without the two fabrics exactly touching all the time.

That being said, it's not too long of a fix.

Re: 1/2" gap in bumpers, is this acceptable?
 

That's... not a 1/2" gap. More like a 1"-2" gap.

I'd go with Peter's suggestion: unwrap the end, cut the noodles, and replace with a vertical section of noodle. You've got time now (and presumably some extra noodle sections laying around), so fix it now and fix it right so you don't have to fix it in a big hurry at the competition.

Re: 1/2" gap in bumpers, is this acceptable?
 

It's 1/2" wide gap that is 2" long.

We have oodles of noodles (oh how long have I waited to post that!) around the shop, so we'll do a quick fix and upgrade the plans for the "red" set.

Thanks to all that replied either here or via PM's.

Re: 1/2" gap in bumpers, is this acceptable?
 

You didn't follow the instructions exactly, and this is the result. (And I don't mean that to sound condescending, I'm just stating a fact.)

Notice the corner labeled "Not OK" in Figure 8-2. Also notice the word "filled" in the rules. I never stopped to think about this before, because the last year I actually worked with the bumpers was before the filled corner rule came into effect. My first reaction would have been, easy, just make the noodles longer and it will work. I guess you've inadvertently proved I would have been wrong. Using a 5" vertical noodle works because it naturally moves around the end of the backer board, whereas an extended horizontal noodle ends up sticking out straight.

Unfortunately I think you'll have to fix it.

Edit: You might also be able to get away with lengthening the noodles on the "butted" end to achieve full corner protection, but you take a risk of that not passing because it doesn't match one of the three ways mentioned in the rules. I think I recall a Q&A last year that said it was OK. If this is your solution, you might ask Q&A, because last year's rules don't apply to this year's game.

Re: 1/2" gap in bumpers, is this acceptable?
 

Foster,
As much as I hate to go against Gary, the intent of the the bumper rule is to have no hard parts in the corners that can contact another robot. At first it would seem like this picture is a violation but I think if you hit the upper right corner of the bumpers, you would not be able to hit the hard parts of the two bumper sections nor the corner of the frame. Of particular note are these paragraphs in R07...
A. BUMPERS must provide complete protection of the entire FRAME PERIMETER of the ROBOT (i.e. BUMPERS must wrap entirely around the ROBOT). The BUMPERS must be located entirely within the BUMPER ZONE when the ROBOT is standing normally on a flat floor, and must remain there (i.e. the BUMPERS must not be articulated or designed to move outside of the BUMPER ZONE).
and
N. “Hard” parts of the BUMPER (i.e. plywood backing, fastening system, and clamping angles) may extend up to a maximum of one inch beyond the FRAME PERIMETER. “Soft” parts of the BUMPERS (i.e. pool noodles and cloth covering) may extend up to 3½ inches beyond the FRAME PERIMETER.

The only thing that appears to be a little long is the top bumper section. The hard part cannot extend past the corner of the frame by more than an inch. In this view I cannot tell whether the wrap of cloth is over a hard part or not. Touch would be the only way I could tell.

Re: 1/2" gap in bumpers, is this acceptable?
 

Does your plywood overlap the corner and butt your other corner, if it does you are also in violation.:eek:

Re: 1/2" gap in bumpers, is this acceptable?
 

I agree with Al, I believe the bumpers meet the intention of the rule. If you were at his event, he'd pass you (subject to the hard parts, which to me looks like you might be OK, but like Al I'd have to feel it). But what will the inspector at your event say? Do you want to risk it?

Re: 1/2" gap in bumpers, is this acceptable?
 

What I'm concerned about is there is a segment of bumper left flapping in the breeze. This could potentially become snagged on something. I hate to say it, but legal or not, I would not want to compete with a bumper quite like this. You have time, go ahead and redo it a bit.

Re: 1/2" gap in bumpers, is this acceptable?
 

There isn't a segment "flapping". The part that is sticking out is the two 2" pool noodles wrapped in fabric.

We have noodle bits cut to fill in the gap and our Master Bumper Builder will do the quick fix this weekend.

Thanks again for all the input!

Re: 1/2" gap in bumpers, is this acceptable?
 

New improved bumpers showing better fit and the new spiffy red color. We put another section of foam in the bumper end.

Re: 1/2" gap in bumpers, is this acceptable?
 

Of note here - in some previous years, it was NOT required to have soft bumper material in the corners. Specifically, i know our first year (2007) we build our bumpers with no material at all in the corners, and they were perfectly legal.

Since then, we've cut all of our pool noodles at 45 degrees to fill the corners nicely.

Re: 1/2" gap in bumpers, is this acceptable?
 

we do too, i think. (BTW, never leave the robot supported by it's bumpers for an extended period of time, we did that to last year's bot recently, and the bumpers are squished down to half their normal size)

Re: 1/2" gap in bumpers, is this acceptable?
 

I'm referring to 2009 with my post, which has similar bumper rules other than allowing for cuts.

Re: 1/2" gap in bumpers, is this acceptable?
 

the one thing you have to make sure of is at the meeting point of the two bumpers, they have to form a perfect L shape..

Re: 1/2" gap in bumpers, is this acceptable?
 

Good evening, As an inspector. No. You must over lap with noodles. Picture in
rules is good.

Mentor Mac
Inspecting at DC and Baltimore
Thomas(just give me a crabcake)
McCubbin

Re: 1/2" gap in bumpers, is this acceptable?
 

Sit around the inspector area and find the guy that is using sound judgement, letting stuff like that slide, and then take your robot to him. If you can kick a bumper in all locations with a size 12 hiking boot, it should pass. That's the idear behind all those rules anyhoo.

Back in the flag pole days I sent our poor overworked teacher out for some 1/2" PVC. She came back with CPVC. Well I said, any body with 1E11 brain cells to rub together knows that in every conceiveable way, CPVC is better than PVC and it would take a draconian, kitten-kicking, monster to tell these little puppy dog eyed kids, at 7:59pm on thursday, that he would not approve their robot with a CVPC pipe. If I was not so gracious, I would have let my feelings be known in no uncertain terms.

Re: 1/2" gap in bumpers, is this acceptable?
 

Travis, while I couldn't agree with your opinion more, I think that the stickler inspectors are pretty representative of the "real world" of engineering where constraints must be followed to the defined tolerance. Since FIRST doesn't allow in the rules for the bumpers to be spaced apart a little, aren't we cheating our kids out of part of this competition which is meant to be a microcosm of the real world?

I've reffed lego league before and while it sucks to have to be the one to tell a kid that their creation isn't legal (even if the rule is poorly stated), it's part of the program. There's some pretty brilliant minds at work in the GDC and while they do slip up every now and then, they usually have a pretty good reason for some of the more annoying rules. :)

thanks, Vivek

Re: 1/2" gap in bumpers, is this acceptable?
 

Travis,

You can be part of the problem or part of the solution. If the latter, I very, very, very strongly suggest that you volunteer to be a robot inspector at your events. They are always looking for help and, obviously, you are equipped, with your with 1E11 brain cells, to do the job far better than the draconian, kitten-kicking, monster you have, unfortunately, met in the past.

Regards

Mike

Re: 1/2" gap in bumpers, is this acceptable?
 

I think we may be in the same boat, but there are worse possible things to have to do than fix some bumpers. In perfect hindsight and looking at the rules I can also see a disconnect between the text portion that says the bumper backing plywood is the same length as the side of the robot. ( Im paraphrasing but we all can see where this comes from ).

So if one builds the plywood to the dimension of the robot and then covers the plywood you might not get a gap in the corners but you won't necessarily get the foam and cloth covering to extend much further than the end of the backing piece either. This is basically where we are at.

You can see in the attached photos how our bumpers meet in the corners, I suppose the worse case scenario is now to open them back up and stuff a vertical piece of noodle in the corner to fill it out a bit, and then cover it back up and hope there are no gaps in the fabric.

Would be great if these are legal, but again, for us there are a lot of other and bigger fish to fry in the time remaining.



Mike

Re: 1/2" gap in bumpers, is this acceptable?
 

Mike,
I am sorry to tell you this but the bumpers as pictured do not meet the rule. Specifically there are many parts to the rule but there are two parts that apply...

A. BUMPERS must provide complete protection of the entire FRAME PERIMETER of the ROBOT (i.e. BUMPERS must wrap entirely around the ROBOT). The BUMPERS must be located entirely within the BUMPER ZONE when the ROBOT is standing normally on a flat floor, and must remain there (i.e. the BUMPERS must not be articulated or designed to move outside of the BUMPER ZONE).

K. As part of the 100% coverage, BUMPERS must protect all exterior corners of the FRAME PERIMETER. For adequate protection, a full segment of BUMPER must be placed on each side of the corner (see Figure 8 - 2).

All is not lost as there is a fairly easy fix. All you need to do is add a 5" length of pool noodle, vertical orientation, at each end of the front and back bumpers covered in the fabric. This additional 2 1/2" of foam protects the corner and overlaps the adjoining bumper section. This addition must have no backing so you do not need to replace the 3/4" plywood backing. As I pointed out earlier, a little gap as shown in the first picture in this thread is expected and fits the rules that require complete frame coverage and satisfies that there are no hard parts in the corners.

Re: 1/2" gap in bumpers, is this acceptable?
 

Mike, that's a great picture of what most bumpers looked like several years ago... But last year and this year, unfortunately, it's not legal. As Al said, however, it's a fairly easy fix, provided you left enough cloth material there to cover the additional few inches.

As a real-life lesson here (adding to what vivek16 said about tolerances), can any of you think of a current, rather big issue for a major company that revolves around tolerances?

Toyota has recalled millions of cars recently due to a stuck gas pedal. Having seen videos of the procedure to fix it, the problem is one of tolerances. The pedal depresses a switch, indicating how fast the car should go by how far the switch is depressed. Well, there's a small gap between the pedal and the switch - small enough that something can get stuck in there and hold the switch down when the pedal is not being pressed. The solution? A small shim stuck in there to fill the gap and prevent anything from getting stuck there.

If the gas pedals were made to stricter tolerances, Toyota wouldn't have this problem. They wouldn't be facing a congressional inquiry, they wouldn't have had to stop sales of those vehicles (losing millions of dollars per day in the process) and spend millions of dollars fixing cars currently on the road. Tolerances are a big issue in industry - both in knowing what tolerances are acceptable for a part and in being able to meet those tolerances.

Learn from Toyota's example. In their case, a gap of 1-3mm cost them millions of dollars. Granted, we don't have to be that exact with the robots or the bumpers... but it is a valuable lesson.

Re: 1/2" gap in bumpers, is this acceptable?
 

Thanks for the information. I suspected as such and we will fix them. Im not complaining about the rules per se, but I think our confusion is understandable, coming from what we viewed as a disconnect between the text and the diagram. In my humble opinion, a simple jpeg would have eliminated much confusion.

I really try to avoid lawyering up , as we put it here, about the rules and how they are interpreted. We see it a lot with students unfortunately, they will go outside the rules here at school and then instead of just modifying a behavior will spend an inordinate amount of time explaining why the rule is unfair or how come someone else gets to do this or that. After one summer of little league umpiring many years ago, I know anyone out there who has dealt with that scenario will know immediately what I mean.

Thanks much, if all our other issues were as simple as stuffing some noodle in the corner of a bumper!

Mike

Re: 1/2" gap in bumpers, is this acceptable?
 

Mike,
I am glad we were able to help. We are striving to train inspectors for all competitions in the fine art of helping, rookie teams especially. I would expect that your inspector would have given you the same advice at your first competition. Good luck and have a great year.