2nd Most Awaited Q and A Answer?

[Dale]

The GDC just replied to my question about appendages during deployment. It's pretty clear now...they must always be contiguous:

Here is the question and response:


Q. To prevent differing interpretations of G21 and the following Q&As on appendages could you address the legality of a appendage BRIEFLY crossing the frame perimeter in multiple places during deployment? For example, a "H" shaped appendage might cross in two places as it quickly folds out.

A. Any time the appendage is outside the Frame Perimeter, it must be a contiguous piece.

[lemiant]

Well this is a puzzler. I feel the the GDC has gone one of only a few ways that would create a logically bulletproof interpretation so good on them for that. On the other hand I suspect that lots of teams that don't frequent these forums will get a nasty surprise when they show up for regionals. Lots of teams will have a robot whose minor infraction makes it completely illegal. I wonder how FIRST will address that?

Also I think there should be some provision added to allow for small protrusions such as bolts, because otherwise if two bolt heads happened to cross the frame perimeter before anything else you are still illegal.

[artdutra04]

Originally Posted by Dale

The GDC just replied to my question about appendages during deployment. It's pretty clear now...they must always be contiguous:

Here is the question and response:


Q. To prevent differing interpretations of G21 and the following Q&As on appendages could you address the legality of a appendage BRIEFLY crossing the frame perimeter in multiple places during deployment? For example, a "H" shaped appendage might cross in two places as it quickly folds out.

A. Any time the appendage is outside the Frame Perimeter, it must be a contiguous piece.

Sigh.

Until this morning I had hope that FIRST would finally go an entire season without making an inane ruling about some aspect of the game.

In 2010, the inane ruling was that small rivet and bolt heads could not be considered exempt from frame perimeter calculations, and everyone had to add 1/8" shims to their frame.

In 2011, the inane ruling was that pre-punched metal (that otherwise met all the restrictions of the minibot rules) was prohibited unless it was a Tetrix part.

In 2012, the inane ruling is that mechanisms that common sense says are clearly one contiguous appendage but happen to have two (or more) points cross the frame perimeter plane before the contiguous section does are illegal.

[arizonafoxx]

Can anyone tell me how to make and 'H' shaped appendage that is contiguous during deployment? Or even a 'Y' shaped one for that matter? I guess back to the drawing board to make some sort of 'T' shaped device or upside down 'U'. And there goes any type of whips or bristles on the end of the appendage. I agree with someone who posted earlier that a green box telling us the intent of the rule might have been nice. All the GDC had to say is "do not make any type of sweeper to collect balls our intent of this rule is to make small T-rex arms to lower the bridge." For give me if I'm a little bitter about this ruling. I'm still in shock that the layering of this rule has gotten to this point.

[Bob Steele]

Originally Posted by arizonafoxx

Can anyone tell me how to make and 'H' shaped appendage that is contiguous during deployment? Or even a 'Y' shaped one for that matter? I guess back to the drawing board to make some sort of 'T' shaped device or upside down 'U'. And there goes any type of whips or bristles on the end of the appendage. I agree with someone who posted earlier that a green box telling us the intent of the rule might have been nice. All the GDC had to say is "do not make any type of sweeper to collect balls our intent of this rule is to make small T-rex arms to lower the bridge." For give me if I'm a little bitter about this ruling. I'm still in shock that the layering of this rule has gotten to this point.

We are working on a solution too. Think about "leading" with the contiguous element... perhaps a linkage that moves the appendage out and then down..
Or use two separate controlled motions to move the appendage out and then swing down...

I hope this helps some...

Good luck

[arizonafoxx]

Originally Posted by Bob Steele

We are working on a solution too. Think about "leading" with the contiguous element... perhaps a linkage that moves the appendage out and then down..
Or use two separate controlled motions to move the appendage out and then swing down...

I hope this helps some...

Good luck

Thank you for your support. Yeah we will probably start looking at some type of drawer slider method instead of a rotational method. That way some decorational piece of .0625 flat bar can be at the end of the sweeping appendage.

I also agree with you that we appear to have blocked the GDC into a corner but it seemed necessary to keep all the inspections and ref calls equal across the whole season. I would hate for week 1 to be judge differently than week 6.

I am glad we got a finite ruling now so we can finish our design. It shouldn't be too hard to come up with something

[artdutra04]

I was thinking more about this today and made a grave realization that these two Q&A Forum answers just painted FIRST into a corner that will make nearly all appendages illegal.

Game - The Game » Robot Actions » G21
Q. Our question is similar to FRC1540. We want to put surgical tubing "whips" on a roller located at the frame perimeter. When this rotates the whips will extend beyond the frame perimeter. Is each "whip" its own apendage or is the assembly considered one appendage? FRC3219 2012-02-01
A. If multiple items exit the Frame Perimeter and are not contiguous outside the Frame Perimeter, they are considered multiple appendages.

Game - The Game » Robot Actions » G21
Q. To prevent differing interpretations of G21 and the following Q&As on appendages could you address the legality of a appendage BRIEFLY crossing the frame perimeter in multiple places during deployment? For example, a "H" shaped appendage might cross in two places as it quickly folds out. FRC1540 2012-01-30
A. Any time the appendage is outside the Frame Perimeter, it must be a contiguous piece.

What this means: if you follow these two Q&A rulings strictly, all wheels, gears, sprockets, rollers, or any other type of rotary motion device (with an axis of rotation parallel to the frame perimeter) on an appendage are now illegal.

Why?

There will always be a portion of the wheel, gear, or sprocket that is dis-contiguous from the rest of the appendage for the small duration of time between which the edge of the wheel, gear, sprocket, roller, etc breaks the plane of the frame perimeter and when the shaft breaks the plane.

Photos are worth a thousand words:

Image 1: What common sense would define as a contiguous appendage. In this case, it's a simple wheelie bar that extends straight outwards. The grey part is the robot base, the black side is the frame perimeter. The light red, blue, and green parts are an appendage that comes straight out. This appendage is entirely inside the frame perimeter and is legal.




Image 2: The appendage has started to break the frame perimeter and extend outward! This is a section view of the CAD assembly, looking outward from the frame perimeter. So far, so good. The appendage is contiguous.




Image 3: The appendage has continued to expand out, but it's now illegal! The portion of the wheel that has broken the plane of the frame perimeter is now dis-contiguous (outside of the frame perimeter) from the rest of the appendage!




Image 4: The appendage continued to expand outwards, and the axle of the wheel finally broke the plane of the frame perimeter! The wheel is now 100% contiguous with the appendage outside the frame perimeter again and is legal once again.




As these images very clearly show, unless the FRC GDC intended to ban all wheels, gears, sprockets, or rollers with a axle/shaft parallel with the frame perimeter, there must be an exemption of the contiguous mandate for appendages in the act of deploying.

There is a very simple solution solution to this fix this problem: only require the appendage to be contiguous outside the frame perimeter when it contacts or reacts with some element on the playing field.

[Bob Steele]

Art
You are exactly correct. That would be a noncontiguous deployment under a strict interpretation of the QA answer...

However, it could also be interpreted that the entire assembly including the wheel or gear is the appendage. If this is true, then the appendage would be contiguous outside the frame perimeter.....otherwise you could not put it out... because there would be two appendages....for a brief time...

This is, in essence the same issue with a rotating roller with small stubs of tubing on it... what IS the appendage??? Is it the entire unit? or bits of the unit as they move over the perimeter?


this is really getting ridiculous isn't it?

[Jared Russell]

Art,

Clearly the wheel and it's supporting structure are the same appendage. In Image 3 it is obvious that the portion of the frame perimeter crossed by this appendage is contiguous. Whether or not that's how the GDC wrote it, that's clearly (IMO) what is intended.

[Dale]

Just in case you weren't following this question on Q&A, here's another response on this theme:

Q. Thanks for the additional G21 clarification. I would appreciate a bit more clarification, primarily regarding your 2012-01-27 response to FRC0063. Can more than one component of a contiguous appendage assembly outside of the frame be simultaneously crossing one edge of the frame perimeter? Thanks.

A. Yes, provided any part of the appendage that is outside the Frame Perimeter is contiguous.

[Austin2046]

From the answers the Q&A has given, i don't see the image of the wheely bar as described above or an H-shaped appendage, as violating the rules about appendages. Here are the questions and answers again:

Game - The Game » Robot Actions » G21
Q. Our question is similar to FRC1540. We want to put surgical tubing "whips" on a roller located at the frame perimeter. When this rotates the whips will extend beyond the frame perimeter. Is each "whip" its own apendage or is the assembly considered one appendage? FRC3219 2012-02-01

A. If multiple items exit the Frame Perimeter and are not contiguous outside the Frame Perimeter, they are considered multiple appendages.

Game - The Game » Robot Actions » G21
Q. To prevent differing interpretations of G21 and the following Q&As on appendages could you address the legality of a appendage BRIEFLY crossing the frame perimeter in multiple places during deployment? For example, a "H" shaped appendage might cross in two places as it quickly folds out. FRC1540 2012-01-30
A. Any time the appendage is outside the Frame Perimeter, it must be a contiguous piece.

Q. Thanks for the additional G21 clarification. I would appreciate a bit more clarification, primarily regarding your 2012-01-27 response to FRC0063. Can more than one component of a contiguous appendage assembly outside of the frame be simultaneously crossing one edge of the frame perimeter? Thanks.

A. Yes, provided any part of the appendage that is outside the Frame Perimeter is contiguous.

From the first answer our appendages have to be continguous outside of the frame perimeter. From the second answer our appendage has to be a contiguous piece when it's outside the frame perimeter. From the third answer more than one component of a contiguous appendage assembly can be simultaneously crossing one edge of the frame perimeter.

The way i interpret this is that our H shaped appendage is fine as long as when the appendage is fully deployed our cross member is located outside the frame perimeter. The second answer only means that two separate things can't join together to form one appendage after each breaks the frame perimeter, or that they can't separate after they've broken the frame perimeter (they stay one contiguous piece outside the frame) The answer doesn't say that an appendage can't cross the frame perimeter in multiple places. The third answer says that it can, as long as the multiple places are contiguous with eachother, not neccesarily contiguous outside of the frame perimeter.

So when the 2 ends of the H are going outside the frame perimeter 2 components of a contiguous appendage are crossing the frame perimeter. The appendage is contiguous while being deployed, and when the H is fully deployed the cross member is outside of the frame perimeter making it one appendage.

[EricH]

Austin, that's the common sense interpretation.

The problem is, that's not necessarily what the GDC said.

Can more than one component of a contiguous appendage assembly outside of the frame be simultaneously crossing one edge of the frame perimeter? Thanks.

A. Yes, provided any part of the appendage that is outside the Frame Perimeter is contiguous.


To put the answer another way, if it's outside, and part of a contiguous assembly, the part that's outside has to be the contiguous part.

To be fair, you could apply the "is contiguous" to either "any part" or to "appendage". That's probably where we're differing--we're applying it to the "any part" and you're applying it to the "contiguous".

[Dale]

Q. Thanks for the additional G21 clarification. I would appreciate a bit more clarification, primarily regarding your 2012-01-27 response to FRC0063. Can more than one component of a contiguous appendage assembly outside of the frame be simultaneously crossing one edge of the frame perimeter? Thanks.

A. Yes, provided any part of the appendage that is outside the Frame Perimeter is contiguous.

I read this latest response as allowing "U" shaped appendages where the solid portion is facing outwards. No big surprise there. Those cross the frame perimeter in two places but are contiguous when outside of the frame. There's nothing about this that allows "H" shaped appendages (during deployment) in my estimation. My original question to GDC mentioned that specifically and they disallowed it.

[Siri]

Originally Posted by squirrel

The last week of build, iirc.

If you're depending on getting the "right" wording on the inspection checklist for a mechanism on your robot to be legal, you might want to redesign the mechanism NOW

Thanks. We're legal (it's more a "D" than anything else), but for anyone who is looking only to the robot rules or inspection checklist, don't forget G21. As a ref, this is all very painful. At least inspectors get to slowly look at one robot however they'd like. I shudder at what could be required of refs in terms of G21. Will the inspectors take care of it all, or do we need eagle eyes to tell which edge/component crossed the perimeter first? What if I see a partially obscured Y/V/U and mistake it for two "1"s?

Originally Posted by artdutra04

What this means: if you follow these two Q&A rulings strictly, all wheels, gears, sprockets, rollers, or any other type of rotary motion device (with an axis of rotation parallel to the frame perimeter) on an appendage are now illegal.

Note that this only applies if the shaft is parallel to the frame perimeter plane (or angled but not long enough). Perpendicular shafts should be fine. (This also applies to H's that are vertical or I-shaped crossing the perimeter.) Well, both should be fine, but perpendicular shafts are fine even accepting ridiculousness.

[Dale]

I'm just adding these two new Q&A responses here for those who aren't following Q&A's on the topic. Nothing really new:


Q. It seems the appendage definition Q&A started out innocently requesting clarity, but led to being over-scrutinized. I suspect the intent of G21 is that an appendage is simply “a contiguous assembly of parts originating from inside the frame and can extend beyond one frame edge 14”.” Please confirm.

A. There is no formal definition of appendage. All pieces of an appendage outside the Frame Perimeter must be contiguous outside the Frame Perimeter.


and


Q. The appendage confusion stems from two conflicting replies: 1) “an appendage is a contiguous assembly that may extend beyond the frame”, and 2) “an appendage, when extended beyond the frame, is a contiguous assembly”. It seems reply #1 is your intent and in the spirit of the rules. Please confirm.

A. Both answers are the intent of the Rule.