New Bumper Rule makes West Coast drive Illegal?

[Tristan Lall]

Originally Posted by Kevin Sevcik

I submit the following two photos into the evidence:
http://www.chiefdelphi.com/media/photos/31159
http://www.chiefdelphi.com/media/photos/23644

A 38" span of bumper isn't likely to survive many of those.

As you say, high quality marine hardwood bumpers with reasonable length spans would be more than fine, and we both know that. But the bumper specifications don't call for high quality plywood, nor maximum span lengths. Instead, they call for the bumpers to be fully supported along their length, which serves a similar function of protecting rookies from underestimating impacts and ending up with snapped bumpers. The rule is, after all, ultimately there to protect less experienced teams from themselves. As are a large number of the rules. Which is why I don't spend time railing against having to electrically isolate everything from the robot frame, the various fusing rules, and other things that I know enough about to do differently and better.

If you compare the failure modes of those electrical rules (burning wires, short circuits, etc.) to the costs of imposing them (it's easy to spot an out-of-place breaker, or test for a grounded chassis), it's a pretty reasonable proposition to mandate those things.

On the other hand, even assuming a violent collision, what's the failure mode of a snapped bumper—plywood hanging limply from cloth? That's hardly in the same league as an electrical fire. (And the bumper repair might even be straightfoward: cut the ends smooth to make two bumpers, and re-brace it somehow.)

So, while you could attempt to define what's a strong frame and what's sufficient structure, and then assess every robot by those standards, I don't think you're going to get much value for the effort (because most bumpers don't break, and the ones that do are probably not a big deal). I also think that you run the risk of inconsistent officiation ("strong enough" is probably a subjective measure) and dispute (because teams will probably believe that their solution is sufficient).

But if a guideline (rather than a rule) captures the intent to caution teams against weak bumpers, why not just opt for that? What's the point of trying to define a frame, and then having to enforce that ruling? And what's the harm in putting the (rather light) burden of building a robust bumper squarely on the teams? I hope that when this gets asked to the Q&A, that they take the opportunity to issue that caution, and just let teams pay harmless lip service to the rule (at their own peril).

After all, although I'm a fan of specificity in rule-making, I don't think that there's a significant benefit for FIRST to interpret this in anything but the most permissive manner.

[dtengineering]

In lieu of a GDC approved definition of "supported", I agree with Tristan that it is not up to the inspectors to make on the site decisions as to what does, or does not, constitute support. If a frame piece provides even the most marginal degree of support... then it is within the rules as they are written now (subject, I am sure, to a Q and A response in the very near future.)

One of the difficult things about being an inspector is to read the rules as they are written... not as you think they should be written. In the spirit of natural justice and fair play that which is not forbidden by the rules must be permitted and that which is required by the rules must be required... even if as an inspector you think the rule is nuts and/or inadequate.

But what would an FRC game be without a few bumper rules to keep things exciting.

Jason

[GaryVoshol]

There's also changes in the bumper attachment rules.

[Paul Copioli]

I noticed the changes in the bumper rules, but the picture didn't change. It looks like it specifically allows other forms of attachment other than what is pictured. Good, now I do not have to "discuss" this with Tristan and Ed Sparks at Championship this year.

[GaryVoshol]

This year's rule: "nut and bolt fasteners are recommended" - Last year that was a MUST.

Additional fastener parts can be attached to the bumper itself this year - the rules specifically mention brackets.

There is in increase to 18 pounds for max bumper weight (was 15).

The pool noodles can be beveled at the ends of the bumper pieces to make a fit around the outside corners of the robot.

[Tristan Lall]

Originally Posted by Paul Copioli

I noticed the changes in the bumper rules, but the picture didn't change. It looks like it specifically allows other forms of attachment other than what is pictured. Good, now I do not have to "discuss" this with Tristan and Ed Sparks at Championship this year.

Believe me, I'm just as relieved as you are that they greatly improved the bumper rule for this year.

[Ed Sparks]

Originally Posted by Paul Copioli

..... Good, now I do not have to "discuss" this with Tristan and Ed Sparks at Championship this year.

I'm sure we'll find other things to "discuss" ......

[The phenom]

so they always have to be touching?

[EricH]

Originally Posted by The phenom

so they always have to be touching?

Do what always have to be touching? The wheels or the bumpers?

If it's the wheels, no.

If it's the bumpers, they better never touch the regolith intentionally...

[nnfuller]

I think he meant that the bumbers must always be touching the robot at all points. and that is true, not just the robot though, the "robot frame/chassis" but don't worry about it just mount a small piece of something outside your wheels and bolt your bumpers to that. it's like a one pound maximum fix.

[NickE]

Originally Posted by nnfuller

I think he meant that the bumbers must always be touching the robot at all points. and that is true, not just the robot though, the "robot frame/chassis" but don't worry about it just mount a small piece of something outside your wheels and bolt your bumpers to that. it's like a one pound maximum fix.

However, the Q&A has clearly clarified that not anything counts as a structural frame member. I would consider an 1/8" aluminum plate slightly more than "a small piece of something", yet the GDC has said that it is not structural [enough] and does not fulfill the intent of the rule. For those teams that typically build a west-coast drive, it is certainly worth worrying about.

[Team2339]

We dissasembled last years robot and found a cracked piece of marine grade plywood for the 27" bumper, but it held.
A structural piece of aluminum angle would work for the "frame support", A plate would be suspect. Just my opinion though.