Al's Annual Inspection Thread 2013

[bhughes]

Originally Posted by EricH

If you look at Figure 4-4, it shows an optional "backing"--though it's more of a clamping system for fabric--that is metal. However, I caution you that R24 (no subpart) and Figure 4-4 combine to bar any other type of metal backing (and note Al's comments on the heavy stuff inspectors have been telling teams to pull out of bumpers, as well--he is, after all, the lead lead robot inspector).

In my opinion, your opinion is correct.

How exactly do they bar any other type of metal backing though? I'm not sure how they exclude any such thing.

[Jaxom]

Originally Posted by bhughes

How exactly do they bar any other type of metal backing though? I'm not sure how they exclude any such thing.

Because the rule says: "BUMPERS must be constructed as follows," and then lists a very limited set of very specific things. There's nothing there about "optional metal backing." Also note that the optional metal angle is required to be aluminum.

[Mike Betts]

Originally Posted by DRH2o

...The fact is that the inspection process is flawed and needs to be fixed...

Dan, et al,

You are an 8th year veteran mentor on an 8th year veteran team. I am quite sure that your students can handle pit duties quite well without you hovering over them...

Volunteer to be an inspector. Your knowledge and insight will be valuable to the community (especially the rookie teams).

Bottom line: You can be part of the solution if you choose to be...

How's this for a suggestion:

<Soapbox>

Every team with greater than 3 years experience donates a mentor on Thursday to help with the inspection process. If you are not a technical wizard, OK. You don't need a Masters in engineering to weigh a robot or measure a set of bumpers.

Think of a 60 team regional with 40 or 50 inspectors. Waiting would be negligable and rookies would receive undivided, top-shelf support. And when the inspectors return to their teams, they take that experience back with them (even veterans can learn)...

</Soapbox>

Regards,

Mike

[Ben Martin]

Bumper question for Al and the rest of the inspection community:
When creating the "rigid fastening system" specified in R24-E with brackets, would you be required to use smaller connection brackets like Andy sells here, or could you have one continuous piece of attachment material stretching across the frame? I am seeing questions about metal backing on bumpers, and I was curious how inspectors would determine legality if the "rigid attachment system" was a continuous bracket running along the frame for 17+ inches.

[FrankJ]

The bumpers are weight limited to 20lb. With this years smaller frame perimeter that still leaves a lot for a "robust" connection. At some point though I would think it would become a flag to see what other rules you are pushing the limits to.

[JVN]

Originally Posted by Jaxom

Because the rule says: "BUMPERS must be constructed as follows," and then lists a very limited set of very specific things. There's nothing there about "optional metal backing." Also note that the optional metal angle is required to be aluminum.

Actually, they say quite a bit more. Paraphrasing rules can be extremely counter-productive in discusssions like this.

Those playing the home game can check out the full manual here:
http://frc-manual.usfirst.org/viewItem/181
Do a ctrl-F for "4.1.6" and read from there

Check out R24E:

Bumpers must attach to the FRAME PERIMETER of the ROBOT with a rigid fastening system to form a tight, robust connection to the main structure/frame (e.g. not attached with hook-and-loop or tie-wraps). The attachment system must be designed to withstand vigorous game play. All removable fasteners (e.g. bolts, locking pins, pip-pins, etc.) will be considered part of the BUMPERS.

This rigid fastening system which is openly listed as a legal part of the bumper is not defined, anywhere. Nowhere. Not anywhere.

So it seems to me that as long as this fastening system fulfills all the other rules regarding bumper construction (the big ones being overall weight, and protrusion distance beyond the robot frame) then teams are allowed to do quite a bit creatively.

If you think back a few years, this fastening system was much more defined. The GDC (I believe) intentionally opened up the rules a bit, not only to make the rules simpler, but also to allow teams more room to do whatever attachment methods they want.

As long as the bumpers weigh less than 20 lbs, are rigid enough to survive competition, follow the construction rules which heavily define the outside face of the bumpers and don't have attachment (hard) parts that stick out too far -- does it matter what the construction is?

-John

[artdutra04]

Originally Posted by DRH2o

Exact weight is an indicator of no change.

Not quite. You can take off exactly 3.00 lbs of one mechanism and replace it with 3.00 lbs of a different mechanism.

I have also seen robots that have had exactly no physical changes made (except for code revisions) weigh anywhere between 0.1 and 0.4 lbs different between events.

[FrankJ]

I have also seen robots that have had exactly no physical changes made (except for code revisions) weigh anywhere between 0.1 and 0.4 lbs different between events.
Today 11:10 AM

I have often wondered what software weighs.

[blayde5]

To address people's concerns about bumper legality during matches,

During eliminations, we had at least the lead robot inspector behind the field with the volunteers ready to re-inspect any robots as well as make sure they were compliant during the match.

Some times, the head ref would catch something that we couldn't necessarily catch during inspection (for example, one robot was tearing up the field due to its pick-up mechanism) and ask us inspectors to rectify it or at least investigate it before the team took their robot off the field.

I myself was behind the field with the rest of the volunteers quickly making sure there wasn't any obvious flaws that teams missed as an inspector (bumper fabric dragging on the ground, new mechanisms that hadn't been inspected, etc.) A lot of teams had made changes during eliminations to add a new mechanism and those had to be re-inspected quickly before their next elimination match.

Moral of the story: feel free to make changes to your robot, just make sure that they're compliant and then please find an inspector well before your next match starts so we can re-inspect it

[Jaxom]

Originally Posted by JVN

Actually, they say quite a bit more. Paraphrasing rules can be extremely counter-productive in discusssions like this.

Maybe, but it can also make posts shorter. But in any case, that's not a paraphrase; that's a direct quote, except for adding emphasis to "must". I'd hope that anyone that's concerned about this particular debate has a copy of the rules at his or her fingertips and could read the parts I didn't include.

The question I was answering was "how can you exclude metal backing?" Having the rule written the way it is allows a logical way to do that, and that's all I was trying to say.

Originally Posted by JVN

As long as the bumpers weigh less than 20 lbs, are rigid enough to survive competition, follow the construction rules which heavily define the outside face of the bumpers and don't have attachment (hard) parts that stick out too far -- does it matter what the construction is?

Apparently, yes:

Originally Posted by Al Skierkiewicz

There are some nice drawings that are part of the rule, in particular Figure 4-4. However, please note, the pool noodles and the bumper rules do not allow for the addition of weight to increase the overall weight of the robot. You may not add steel rod, brass, shot or other high mass material to the interior of the pool noodles. Also note that the optional angle stock shown in Figure 4-4 is specified as aluminum. If your bumpers are modified in a such a way, please be prepared to remove the additional weight at your event.

I think we're well into the "lawyering" of the rules that we've been encouraged not to do. I'm having trouble coming up with a reason to add metal backing to the bumpers for any reason except to add weight. Please share if you have something else in mind.

[ebarker]

Originally Posted by FrankJ

I have often wondered what software weighs.

One Strawberry.

[Mk.32]

Originally Posted by FrankJ

I have often wondered what software weighs.

I would rather think it's just the scales being calibrated differently/error within the scales.

[Tristan Lall]

Originally Posted by Jaxom

I think we're well into the "lawyering" of the rules that we've been encouraged not to do. I'm having trouble coming up with a reason to add metal backing to the bumpers for any reason except to add weight. Please share if you have something else in mind.

Al is describing a situation that comes up every so often, where a team will hide something heavy within the cushion of the bumpers (to adjust centre of mass or increase total mass). If there's no pretense of making it part of any of the elements described in the rules, then it's not allowed.

What he's not saying is that those materials are inherently prohibited in all possible bumper applications.

Teams use enormous aluminum angle to add weight. Teams use heavy fasteners and brackets to add weight. There is no rule against adding weight, and if teams comply with all the other rules, it's legal.

[JVN]

Originally Posted by Tristan Lall

Al is describing a situation that comes up every so often, where a team will hide something heavy within the cushion of the bumpers (to adjust centre of mass or increase total mass). If there's no pretense of making it part of any of the elements described in the rules, then it's not allowed.

What he's not saying is that those materials are inherently prohibited in all possible bumper applications.

Teams use enormous aluminum angle to add weight. Teams use heavy fasteners and brackets to add weight. There is no rule against adding weight, and if teams comply with all the other rules, it's legal.

That is my interpretation, also.

The undefined rigid fastening system can be a heavy, rigid fastening system, as long as no other rules are violated.

I'm not clear if Al is saying something different. I'm also curious if there is an official interpretation other than Al on the forum. I saw someone submitted a Q&A which touches on the subject.

-John

[Alan Anderson]

Originally Posted by artdutra04

I have also seen robots that have had exactly no physical changes made (except for code revisions) weigh anywhere between 0.1 and 0.4 lbs different between events.

At the Championship in St. Louis last year, it wasn't unusual to see a robot weight change by several tenths of a pound based on how people were standing around it. I think the air movement in the convention center was strong enough to put noticeable force on the scale when it came from directly above.