New Bumper Rule makes West Coast drive Illegal?

[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.

[IndySam]

Originally Posted by Tristan Lall

That's exactly why it's hazy, though: let's say I use a 0.19 in thick × 1.00 in tall strip of polycarbonate as the backing material, with several screws into the bumper plywood. Will it be strong enough across a 20 in span? My gut feeling is that under most gameplay, it would not break, or even deflect appreciably. But what if the team used (brittle) acrylic instead? Or if they turned the strip 90° to buttress the plywood? I don't think it makes much sense for inspectors to be trying to make that particular determination—it will just be their best guess, and it's ripe for debate that serves no useful purpose.
If your bumper plywood ever breaks, even with no backing (and especially with the aluminum angle depicted in Fig. 8-1), you're probably doing it wrong. And if you use high-quality hardwood marine plywood (as opposed to the regular softwood stuff), you could probably span over 30 in without any backing, and suffer no ill effects.

I just don't think it's valuable to add a specification here, given that it's one more thing for teams to worry about, one more thing that needs to be checked (consistently) at inspection, and is probably superfluous anyway, given moderately-well-constructed bumpers.

in 2007 we had 38" bumpers on the back of our robot only supported on the ends. They were constructed out of high quality plywood and they were snapped in half, twice.

[MrForbes]

Last year we had the end bumpers (26") fully supported by the chassis, and the side bumpers (36") well supported at the ends, and just touching two standoffs along the sides of the robot (with cantilevered axles). We had no problems at all with the bumpers. Since another team only supported their bumpers at the ends, and did have them break, it seems that not all teams understand what it takes to properly support the bumpers...and that means that the rule does have some merit. But it does change our design plans for this year!

[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.