2nd Most Awaited Q and A Answer?

[Bob Steele]

Originally Posted by jvriezen

My totally unofficial, but unambiguous interpretation of the writings of the GDC.

An appendage is considered a single appendage if, during its normal extension for usage outside the frame perimeter, all appendage components which intersect the frame perimeter projection are contiguously connected entirely outside the frame perimeter projection.

This would allow a 'fork' like appendage to not break the rule when only the tines of the fork are intersecting the frame perimeter during its deployment, but the normal usage of the fork appendage would need to be such that the portion connecting the tines must also be out of the perimeter projection as it is used.

And I don't think it matters if one tine of the fork is used to manipulate balls, and the other tine is used for moving the bridge -- multipurpose appendages are fine.

I would have to respectfully disagree with this line of reasoning. Other than the fact that it is redundant ("contiguously connected") a
contiguous assembly must mean that it is simply connected... the new answer does not say that it has to be contiguous OUTSIDE the frame perimeter. I quote directly from Q&A:

" To elaborate, an Appendage is a contiguous assembly that may extend beyond the Frame Perimeter per Rule [G21]."

I looked at the old wording "an appendage, when extended beyond the Frame Perimeter, is a contiguous assembly" and this simply doesn't make sense...you can't define a contiguous assembly as one that extends beyond the frame perimeter..you define it by the definition of contiguous (ie connected). They were simply cleaning up the answer.


If it looks like an appendage, quacks like an appendage and moves like an appendage...it is an appendage... contiguous means connected..connected could possibly mean moving all at once... but wouldn't have to ..


I think that Q and A is sufficiently clear on this topic. I also think it is unambiguous.

[jvriezen]

Originally Posted by Bob Steele

I would have to respectfully disagree with this line of reasoning. Other than the fact that it is redundant ("contiguously connected") a
contiguous assembly must mean that it is simply connected... the new answer does not say that it has to be contiguous OUTSIDE the frame perimeter. I quote directly from Q&A:

" To elaborate, an Appendage is a contiguous assembly that may extend beyond the Frame Perimeter per Rule [G21]."

I looked at the old wording "an appendage, when extended beyond the Frame Perimeter, is a contiguous assembly" and this simply doesn't make sense...you can't define a contiguous assembly as one that extends beyond the frame perimeter..you define it by the definition of contiguous (ie connected). They were simply cleaning up the answer.


If it looks like an appendage, quacks like an appendage and moves like an appendage...it is an appendage... contiguous means connected..connected could possibly mean moving all at once... but wouldn't have to ..


I think that Q and A is sufficiently clear on this topic. I also think it is unambiguous.

But how could you possibly EVER have two appendages exiting from the same edge then? If they can be connected inside the perimeter, then any thing you want to call two appendages on the same edge will be one by your definition --- unless one is totally disconnected from the bot, which of course violates a different rule. By your line of thinking, I can have any configuration whatsoever for appendage(s) as long as they all exit the perimeter along the same edge-- they are always connected to each other somehow via the bot parts.

[Jon Stratis]

Originally Posted by jvriezen

But how could you possibly EVER have two appendages exiting from the same edge then? If they can be connected inside the perimeter, then any thing you want to call two appendages on the same edge will be one by your definition --- unless one is totally disconnected from the bot, which of course violates a different rule. By your line of thinking, I can have any configuration whatsoever for appendage(s) as long as they all exit the perimeter along the same edge-- they are always connected to each other somehow via the bot parts.

I'm just guessing here, but the big difference is how it's actuated. If a single motor drives two rods out the same side of the frame perimeter, those rods are one appendage. If you have two separate motors driving those two rods out, then they are separate appendages - they can be actuated together, and they can be actuated independently.

[nssheepster]

Originally Posted by Jon Stratis

I'm just guessing here, but the big difference is how it's actuated. If a single motor drives two rods out the same side of the frame perimeter, those rods are one appendage. If you have two separate motors driving those two rods out, then they are separate appendages - they can be actuated together, and they can be actuated independently.

Agreed. Even if they are wired together, it can be separate, so it would count as two. Still, might be best to play it safe, though.

[Siri]

Originally Posted by Bob Steele

contiguous assembly must mean that it is simply connected... the new answer does not say that it has to be contiguous OUTSIDE the frame perimeter.

Can I ask where you distinguish your interpretation versus last week's "fork" answer? I understand the search for clarity in newer answers*, but I can't find the necessary lack of clarity in it to support additional interpretations of this.

Q: If an extension forks outside of the frame perimeter, does it count as a single extension? For example, if 7" away from the frame, the appendage splits into two separate bars.
A. Only one appendage may extend beyond the Frame Perimeter. There are no rules prohibiting appendages that fork once outside the Frame Perimeter.

To me this would seem very strongly (i.e. barring [edit]finagling?[/edit]) to ban appendages that fork within the Frame Perimeter. Have I mistaken that?


*Under the precedent that the GDC will announce if they directly change their interpretation: e.g. "We have recently published conflicting responses in the Q&A...have revised the responses in question and added clarification in the Blue Box" - Team Update 2012-01-20.

[Squillo]

I see that a new question has been asked, and not yet answered by the GDC (thanks 1619). Hopefully they will know of our confusion and resolve it, one way or another.

I am wondering about this: an "H" shaped construction that has two pieces extending past the perimeter, joined by a bar that crosses between them (and is outside the perimeter when the 'appendage' is extended, but crosses from inside to outside during the course of extension), and then two more pieces that continue past the cross bar. Or for that matter, two pieces that cross the perimeter and are simply joined into a "u" with a crossbar outside the perimeter.

Any difference between those two? Either legal/illegal? Thoughts?

BTW, I just have to get this out there. I know it is the GDC's language, and I should take it up with them, but as a lawyer (and mentor/'rulesmeister') I really resent the negative connotation that has been placed on the term "lawyering". It just so happens that a large part of proper legal reasoning, argument and decision-making is focused on discerning the INTENT behind the rule, statute, or contract, and explaining how/why our interpretation is in accord with that INTENT - NOT, as some believe, looking for 'technical loopholes' that are contrary to the intent of the legislature/court/contract drafter. You engineers are MUCH better at that than we lawyers. Maybe we should call it "engineering" the rules...

BTW and FYI, the January 2012 issue of the magazine GPSolo, put out by the general practice, solo and small firm division of the American Bar Association, which is focused on volunteering and community service, contains an article entitled "Mentoring a High School Robotics Team" by yours truly, which details why I do this and plugs robotics in a big way. As soon as the online link is available, I'll post it. Would anyone care to suggest a forum or sub-forum that would be appropriate for that?

[MrForbes]

Originally Posted by Squillo

BTW, I just have to get this out there. I know it is the GDC's language, and I should take it up with them, but as a lawyer (and mentor/'rulesmeister') I really resent the negative connotation that has been placed on the term "lawyering". It just so happens that a large part of proper legal reasoning, argument and decision-making is focused on discerning the INTENT behind the rule, statute, or contract, and explaining how/why our interpretation is in accord with that INTENT

I think we're aware that that is what a large part of proper legal reasoning is. The thing that gives lawyers a bad reputation is the occasional improper use of the technique to find loopholes.

Some of us have learned over the years to look right away for the most conservative interpretation of the rules, it saves a lot of redesign.

[RRLedford]

At what point does an appendage become an appendage?

Is it at its attachment point inside the bot, or at the point where it crosses outward beyond the perimeter? Along what paths are we supposed to trace out contiguity tests. If all bots are 100% contiguous then what establishes dis-contiguousness as relating to appendages?

What exact application of appendageness and contiguity determine whether we have just one, or more than one appendage protruding?

What if our whole robot just expanded in all directions (above the bumpers of course) for 14" beyond its initial size, and we consider this our "frame appendage"? If it is contiguous are we in violation? What if we deploy diagonally at a corner? Can the appendage still only be 14" diagonally from the corner, or (14") X (1.414) -- still within a rectangle going 14" further outward than the frame?

-RRledford

[Tuba4]

Originally Posted by RRLedford

What if our whole robot just expanded in all directions (above the bumpers of course) for 14" beyond its initial size, and we consider this our "frame appendage"? If it is contiguous are we in violation? What if we deploy diagonally at a corner? Can the appendage still only be 14" diagonally from the corner, or (14") X (1.414) -- still within a rectangle going 14" further outward than the frame?

-RRledford

This would clearly violate the following:

[G21] Robots may extend one appendage up to 14 in. beyond a single edge of their frame perimeter at any time.

No need to discuss continuity here. One edge at a time!!!!!

[RRLedford]

Originally Posted by Tuba4

This would clearly violate the following:

[G21] Robots may extend one appendage up to 14 in. beyond a single edge of their frame perimeter at any time.

No need to discuss continuity here. One edge at a time!!!!!

While this rule may well be intended to mean "beyond ONLY a MAXIMUM of ONE SINGLE EDGE," it is not really worded to accomplish this.
Plus, it should have added ==> "and may NOT extend ANY AMOUNT beyond ANY OTHER EDGES of the robot." -- if this was what they really meant.

Consider this example: Let's suppose I tell you to deploy an appendage diagonally at 45 degrees off the corner of our bot for 14" of extension, and the robot is a rectangle.
I then tell you to check whether this arm extends more than 14" beyond any single edge of the robot.
You then report back to me that compared to NO SINGLE EDGE does the robot arm extend more then 14". You verified this by holding up a long straight edge spaced 14" away from each side, one at a time, to confirm this.
This rule's wording can also simply mean that you are comparing the tip of the arm's position to EACH INDIVIDUAL FRAME EDGE LINE ==> ONE LINE AT A TIME. So even though the appendage clearly extends beyond two of the four edges, it does NOT extend beyond 14" for "any single edge " measured ALONE.

BTW, if a circular robot is allowed, does it only have one edge? If so could it deploy a skirt outward, all the way around the robot for up to 14" as long as the skirt formed a "contiguous" loop?
There does seem to be a distinct bias toward rectilinear design concepts with the structure of the FIRST game rules.

-RRLedford

[JamesCH95]

For the love of Andy Baker can we please stop lawyering this into oblivion and use some common sense? The GDC doesn't want to artificially limit designs through inane rule interpretation.

You may have 1 mechanical appendage at a time that may extend up to a 14" offset of your frame perimeter. If the robot is a circle, any appendage must remain within a circle of a 14" larger radius with the same center as the frame perimeter. If your robot is a rectangle then any appendage must remain within a rectangle of 28" greater width and 28" greater length with the same center as the frame perimeter.

The appendage may have forks or splits in it as long as it is mechanically connected in such a way as they must function unison. Your arm+hand+fingers is considered one appendage. Your two arms acting in unison through brain commands (i.e. robot code) are still two separate appendages.

[Tuba4]

Originally Posted by JamesCH95

For the love of Andy Baker can we please stop lawyering this into oblivion and use some common sense? The GDC doesn't want to artificially limit designs through inane rule interpretation.

You may have 1 mechanical appendage at a time that may extend up to a 14" offset of your frame perimeter. If the robot is a circle, any appendage must remain within a circle of a 14" larger radius with the same center as the frame perimeter. If your robot is a rectangle then any appendage must remain within a rectangle of 28" greater width and 28" greater length with the same center as the frame perimeter.

The appendage may have forks or splits in it as long as it is mechanically connected in such a way as they must function unison. Your arm+hand+fingers is considered one appendage. Your two arms acting in unison through brain commands (i.e. robot code) are still two separate appendages.

I concur. You said it much more elegantly and succinctly than I could. I was being too specific. You were more general. Now if only the GDC agrees as well.

[Tristan Lall]

Originally Posted by JamesCH95

You may have 1 mechanical appendage at a time that may extend up to a 14" offset of your frame perimeter. If the robot is a circle, any appendage must remain within a circle of a 14" larger radius with the same center as the frame perimeter. If your robot is a rectangle then any appendage must remain within a rectangle of 28" greater width and 28" greater length with the same center as the frame perimeter.

The appendage may have forks or splits in it as long as it is mechanically connected in such a way as they must function unison. Your arm+hand+fingers is considered one appendage. Your two arms acting in unison through brain commands (i.e. robot code) are still two separate appendages.

The GDC still needs to say so, and say so in a way that clears up the minor inconsistencies. This wouldn't be a bad interpretation for a team to employ (in the absence of clarity), because it's conservative and likely to stand up to scrutiny by competition officials.

But it's not helpful for FIRST officials to each be enforcing slightly different variations on the rules, because the GDC wouldn't clarify things a bit further. That's particularly problematic with the forked appendage rule: what's a valid mechanical connection? Is it literally anything—e.g. the rest of the robot? Is it anything that bears a load of more than a certain amount? Is it anything that looks structural? Is it an issue of degrees of freedom between appendages? Or would a thread tied around two appendages make them one? What if the thread was instead a coathanger? What if it was a tie rod with ball joints at each end?

When inspectors/referees are making rulings, hopefully they're also considering the general case—because what seems good in specific circumstances may have implications for future rulings (if they're consciously attempting to be consistent, which they usually are).

Originally Posted by RRLedford

While this rule may well be intended to mean "beyond ONLY a MAXIMUM of ONE SINGLE EDGE," it is not really worded to accomplish this.
Plus, it should have added ==> "and may NOT extend ANY AMOUNT beyond ANY OTHER EDGES of the robot." -- if this was what they really meant.

Consider this example: Let's suppose I tell you to deploy an appendage diagonally at 45 degrees off the corner of our bot for 14" of extension, and the robot is a rectangle.
I then tell you to check whether this arm extends more than 14" beyond any single edge of the robot.
You then report back to me that compared to NO SINGLE EDGE does the robot arm extend more then 14". You verified this by holding up a long straight edge spaced 14" away from each side, one at a time, to confirm this.
This rule's wording can also simply mean that you are comparing the tip of the arm's position to EACH INDIVIDUAL FRAME EDGE LINE ==> ONE LINE AT A TIME. So even though the appendage clearly extends beyond two of the four edges, it does NOT extend beyond 14" for "any single edge " measured ALONE.

BTW, if a circular robot is allowed, does it only have one edge? If so could it deploy a skirt outward, all the way around the robot for up to 14" as long as the skirt formed a "contiguous" loop?
There does seem to be a distinct bias toward rectilinear design concepts with the structure of the FIRST game rules.

I'm not sure I'm totally on board with the one-edge-at-a-time measurement scheme, because I would tend to assume the rule is to be interpreted simultaneously with respect to all edges—but I concur that it's not clear whether the appendage has to physically cross the projection of an edge, or simply be extended into the space beyond an edge. (Imagine a piece that crosses only one side, but then is actuated so it curves into the space beside another edge. Was it "extend[ed]...up to 14 in. beyond a single edge"?)

As for the rest, you beat me to posting it. FIRST has a history of issuing interpretations that don't make sense with respect to non-rectilinear robots. And they frequently omit things like maxima and minima (or any tolerancing at all).

[Jon Stratis]

In another thread on here (I can't find it now, but it was dealing with bumper rules), someone postulated that a perfectly circular robot, rather than having a single edge on their frame perimeter, would actually have an infinite number of exterior vertices. Under that interpretation, any appendage extending over the frame perimeter would be crossing multiple edges.

As far as inspecting/reffing this rule... there's nothing in inspections that should be affected by this rule. It's perfectly legal for a robot to have as many appendages as they want, and to have them on one side or multiple sides. They just can't extend them all at the same time. So it really comes down to reffing. Refs are going to follow a rather simple rule in calling penalties for this - if it looks like multiple appendages, then it gets penalized. Here in Minnesota, we have 60+ teams at each competition. It's going to be next to impossible for the refs to remember which robots have multiple appendages on the same side, versus which ones have a single appendage that just looks like multiple appendages.

So save yourself and the refs some headaches and make things obvious.

Edit: found the post referencing circular designs: http://www.chiefdelphi.com/forums/sh...2&postcount=43

[RRLedford]

Originally Posted by JamesCH95

For the love of Andy Baker can we please stop lawyering this into oblivion and use some common sense? The GDC doesn't want to artificially limit designs through inane rule interpretation.

You may have 1 mechanical appendage at a time that may extend up to a 14" offset of your frame perimeter. If the robot is a circle, any appendage must remain within a circle of a 14" larger radius with the same center as the frame perimeter. If your robot is a rectangle then any appendage must remain within a rectangle of 28" greater width and 28" greater length with the same center as the frame perimeter.

The appendage may have forks or splits in it as long as it is mechanically connected in such a way as they must function unison. Your arm+hand+fingers is considered one appendage. Your two arms acting in unison through brain commands (i.e. robot code) are still two separate appendages.

Even this "common sense" explanation still lacks clarity as to whether or not an appendage can deploy diagonally off a corner, and, if so, how far?
There may be a 90 degree angle forbidden zone at the vertex of each 90 degree frame corner?
Just going by the "rectangle of 28" greater width and 28" greater length" analysis, could allow a 40+% longer (14" X 1.414) appendage length at corners if the diagonal deploy is legal, but it would still be crossing both of the bot's adjacent frame edge lines, which may not be allowed.

-RRLedford