2nd Most Awaited Q and A Answer?
 

Just wondering how may teams out there are awaiting a "helpful" reply to this question relating to the legality of (what many consider) one appendage that has two parallel arms attached mechanically and structurally so that they act as a singular appendage as they pivot to extend outside the robot...


Game - The Game » Robot Actions » G21
Q. If two members of a mechanism crosses one edge of a robot in two locations but the two members are connected via one axle and are controlled by one motor is this still considered one appendage?
Answer is in pending state
FRC1221 2012-01-14

So do you go ahead and build this "appendage" knowing that sometime down the road you may or may not find out your time and effort was worth it?

Re: 2nd Most Awaited Q and A Answer?
 

Honestly I think this has more reason to be the most anticipated Q&A response.

It may even be considered allowable to have two separate mechanical extensions, but that are otherwise linked to always operate in tandem and in a repeatable fashion (via code), count as a single appendage. But it would be really nice to know for sure. I'm hoping for an answer in the update tomorrow, or at the very least soon in the Q&A.

As for what to do in the meantime: have contingency plans; come up with and test ideas that work in multiple scenarios. Since we are not in a rush to build anything final until about a week from now, we can wait a short while to know what's right, but we don't have all the time in the world. If you are running out of time, go with what's safe, an appendage which is undeniably a single appendage.

Re: 2nd Most Awaited Q and A Answer?
 

We were wondering this same thing, but in the end decided that we can just bend some tubing to avoid trouble.

Re: 2nd Most Awaited Q and A Answer?
 

That's the one thing I don't understand. The Q&A has probably half a dozen questions on appendages alone, and a number of them are "does this scenario count as an appendage?" type questions. I would think that the GDC would see that this is an issue that needs answering. So why hasn't it been answered?

My guess is, whichever GDC member is the "appendage rules expert" hasn't seen the Q&A yet. (It seems that certain question types are answered in groups, both last year and this year; this leads one to speculate that various GDC members are experts in various parts of the Manual. I don't know if this is actually the case, however.) If that is the case, then hopefully another GDC member nudges him/her to answer... some of these questions have been kicking around for a week now.

Re: 2nd Most Awaited Q and A Answer?
 

I seriously hope they realize that defining an appendage based on its construction is a losing game.

Thought experiment: I have a plastic toy trident which can be installed on my robot in several possible orientations, and which can be actuated in several ways during a match. (Imagine the craziest possible positions for this thing, with varying degrees of overhang, flexibility, etc..) If I poll 5 trained, experienced referees about the legality of all of these configurations, can I expect to get 5 identical, correct sets of answers? What if I repeat the test with 5 GDC members?

Almost certainly, the answer is no. Nobody knows what an appendage is, or where it begins, because that definition is not in the rules, and does not obviously follow from an ordinary person's understanding of any given robot design.

Mechanisms can do all sorts of weird stuff, and can take all sorts of forms. You don't want to end up with a definition that makes something an appendage in some positions, and two or more appendages in others. It's also a bad idea because it's non-obvious, and will be full of nuanced interpretations. Good luck getting every referee to call that the same way every time.*

The real way forward is to fix the definitions of frame perimeter and side (so that they properly account for curvilinear figures, and elegantly handle projections into the corners adjacent to two sides), and then allow only one side to be overhung at a time. No mention of what's overhanging, or how many—just a clear test that be applied by a referee with no knowledge of how various mechanisms are actuated.

*That's most assuredly not a slight against referees. The fact is, all officials will struggle with complicated definitions applied to complicated robots. Referees have the additional problem that their struggle takes place in real time, in front of an audience. The stakes are high for them, and they'll be expected to get this right. That's not easy.

Re: 2nd Most Awaited Q and A Answer?
 

They are probably just waiting on wording. Look at the simulator, they have the type of appendage you're talking about. The intent of the rule is not to spread out multiple sides like wings, etc., is my guess.

Re: 2nd Most Awaited Q and A Answer?
 

We have answers...kind of

A. There is no explicit width limit for a Robot appendage. Per Rule [R21], "Robots may extend one appendage up to 14 in. beyond a single edge of their Frame Perimeter at any time."

A. There is no formal definition of appendage, however a colloquial definition is "a subordinate part attached to something; an auxiliary part; addition" (courtesy of disctionary.com). To elaborate, an Appendage is a contiguous assembly that may extend beyond the Frame Perimeter per Rule [G21].

Contiguous - From Websters
1: being in actual contact : touching along a boundary or at a point of angles
2: adjacent 2
3: next or near in time or sequence
4: touching or connected throughout in an unbroken sequence <contiguous row houses>

Re: 2nd Most Awaited Q and A Answer?
 

So it appears according to today's answers that a mechanical linkage, e.g. a mechanically contiguous assembly in any way, will be considered a single appendage. No mention of whether this connection is inside or outside the frame means that it doesn't matter. Good to know this is the way they are thinking, and beyond that I think we can safely use common sense.

Re: 2nd Most Awaited Q and A Answer?
 

This now opens up the question that if its two mechanically independent systems operating in unison (and assumedly being used for the same/similar task), does this still satisfy the requirement?

-Brando

Re: 2nd Most Awaited Q and A Answer?
 

I would think not, and probably call it out as ref/inspector, because of how they appeal to a colloquial definition of appendage, regardless of function. I would want to see a mechanical connection.

Then of course you could tie a string between them to make them "contiguous," but I think that's why they don't want us lawyering the rules.

Re: 2nd Most Awaited Q and A Answer?
 

I agree, thats why the rule seems kind worded kind of silly to me.

Re: 2nd Most Awaited Q and A Answer?
 

I suspect the given answer is a relief for many teams who have spent many days developing flip out, push out linked arm appendages... the GDC got this one conceptually right.

Re: 2nd Most Awaited Q and A Answer?
 

The key issue as I see it is whether or not multiple mechanisms that have either an interrelated/coordinated functional purpose or completely independent functional purposes, can be "contiguously" combined on a single arm that extends beyond the robot's "single edge" (this term is totally vague too - what happens if you deploy off a corner: can you go out 14" X 1.414?).

As long as various mechanisms & their components are purposed for one one function and are contigouosly attached to a single extension arm, this would seem to be within the "spirit" of the rule.

However, what happens if your appendage can extend to grab balls off the floor and then swing up, allowing ball transfer to a separate, but still arm-attached, shooter assembly, that proceeds to fire a scoring shot? Does this violate the "spirit" of the rule. Does the "spirit" of the rule imply only a single functional purpose per each appendage?

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

Anyone else notice that this has changed (in the Q&A)?

Q: What is the Definition of "Appendage"?

NEW answer:
A. There is no formal definition of appendage, however a colloquial definition is "a subordinate part attached to something; an auxiliary part; addition" (courtesy of disctionary.com). To elaborate, an appendage, when extended beyond the Frame Perimeter, is a contiguous assembly.

OLD answer:
A. There is no formal definition of appendage, however a colloquial definition is "a subordinate part attached to something; an auxiliary part; addition" (courtesy of disctionary.com). To elaborate, an Appendage is a contiguous assembly that may extend beyond the Frame Perimeter per Rule [G21].

I have to assume that this change was intentional, and has meaning. I interpreted the OLD answer to mean that as long as it was contiguous, it could extend past the perimeter. The NEW answer seems to mean that it must be "continguous" past the perimeter. So if the connection is within the perimeter, and it's two separate things outside the perimeter, then it's two appendages, even though they are connected?

Help?!!! This is so confusing (and critical to our team - we thought we were OK but now I'm not so sure). I have a feeling the GDC will just keep repeating this (new) answer, but what do you all think it means?

Re: 2nd Most Awaited Q and A Answer?
 

To me that seems to be a good point. Additionally, I'd say that they wanted to say that appendage rules don't apply within the vertical perimeter (remembering the vertical cylinder from last year.

Additionally, I'd imagine that your point would be handled very leniently. Imagine one of the hands from last year with two prongs that grab the tube (this year the ball) and are 4 inches long, but the mechanism holding them takes up your other 10 inches. Withdrawn into the robot and facing out, you then have to extend them. At some time only 2 inches are protruding. By rule they are seperate appendages, but not in practice and therefore I think that they will not be ruled as such.

Re: 2nd Most Awaited Q and A Answer?
 

I'd play it safe and have something that connects the two arms at the outer ends. It's a pain, but it'll save having to deal with the issue later when they finally come out and say that's what they meant all along.

edit: and a bonus, it's less likely to poke into other robots

Re: 2nd Most Awaited Q and A Answer?
 

So to be clear, you can or cannot have one solid piece, reaching out at two different points, as long as the distances don’t add up to more than 14”?

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

I asked several of these questions and similar others. Some were rejected as being questions of if a certain design breaks a rule. They don't answer that. They answer questions about the rule itself.

I asked the question about wings, width etc.

My current interpretation is that they probably made a mistake in the rules and are trying to figure a way out. But the width is constrained within the perimeter frame until the appendage crosses one edge. Once outside the edge it can not go "beyond" that edge by more than 14 inches but beyond implies (in my mind) the direction in which the appendage is moving as it crosses the edge. Once out there, I see nothing to prohibit wings from extending out parallel to the edge that was crossed. These wings won't be crossing a second perimeter edge; perimeter edges surround the robot frame "like a piece of string", they do not extend virtually to the edges of the playing field.

What do YOU think?

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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?

Re: 2nd Most Awaited Q and A Answer?
 

As I see it the uncertainty that needs clarification is the spatial location within which the 'contiguous" test will be applied. If the contiguous test is applied ONLY to what protrudes beyond the robot, then a forked appendage would be in immediate violation at the moment the two or more "tines" crossed the edge perimeter plane, since at that moment they are not contiguous within the space outside the edge of the robot.

By this interpretation, only if the fork tines stayed connected (or at least touching) at their tips until the fork's base broke the perimeter, and only at that point they separated to desired positions, would "contiguousness" be maintained OUTSIDE the perimeter at all stages of appendage deployment.

If the contiguous test allows tracing "contiguity" back inward past the outside perimeter of the bot, that would not make much sense, since EVERY SINGLE component of the robot will ALWAYS be contiguous with every other piece, assuming that parts merely being in contact satisfies the contiguous test.

Since the entire robot is always 100% contiguous with itself, the mere use of the term "contiguous" for appendage testing TOTALLY IMPLIES that that it is meant to be applied ONLY to the portion(s) of the appendage that protrudes from the bot, and applied ONLY to what is occuping the SPACE BEYOND the perimeter.

It is only by delimiting the SPACE that the bot occupies, into an inside of and an outside of the perimeter, that any portion of the robot can ever be considered as "dis-contiguous," based on its relation to the "CUTTING PLANE" of the perimeter.

Imagine a Star Wars lightsabres cutting arcs to match the vertical edge perimeter of your bot. If an appendage starts to deploy, and at any time throughout its maximum of 14" horizontal motion the lightsaber can cut it off, such that TWO OR MORE PIECES fall on the floor, then the appendage probably fails the contiguous-outside-the perimeter test.

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

The following has been posted to the Q & A system:

In a prior answer it was stated that an appendage can fork outside the frame perimeter yielding a Y shaped appendage. Can an appendage be attached to the frame at 2 points and terminate in 2 points as long as they are joined by a cross member, yielding an H shaped appendage?

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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

Re: 2nd Most Awaited Q and A Answer?
 

Why do we need a bar to make the H - shape? The robot it self is the cross bar of the H, at least as far as the contiguity test goes, that could pass.
If the robot itself CAN'T be the H-bar, then where beyond the two pivot points must the H-bar fall? Must it swing out past the perimeter to make it a legal forked arm? What if the deploy fails in the muddle and the H-bar stays inside the robot perimeter while the two tops of the H break the perimeter? Is this a double appendage deploy or can we trace contiguity back inside the perimeter and around between the two sides of the H?

We really need some better clarification on the same level as the way the bumper mounts are detailed with good example diagrams.

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

RRLedford -

We really don't want the entire rule book to go the way of the bumpers - aka super detailed. Take a look at last year's Inspection Checklist - 1/6 of the entire checklist was about the bumpers! If we do that for everything, Inspections will take hours to go though.

The definition of contiguous really isn't that difficult to understand in this scenario. Anyone saying the entire robot makes any number of appendages "contiguous" is lawyering (or engineering...) the rules. That's just ridiculous. Your robot isn't the appendage.

As for your suggestion of a frame that extends in all directions... that would be against many rules. First, your frame must be fixed and non-articulated (R01-2). So your "frame" that extends in all directions at once would be extending past all edges of the frame perimeter, not just one (G21).

The clear intent of the rules would prohibit extending anything through a corner, as that would pass it through two sides of the frame perimeter. Projecting on a diagonal near the corner, however, is a little less clear in the rules... however as the Q&A emphasizes "single edge" in answering a similar question, I don't think that's legal.


TLDR: Use some common sense and stop trying to lawyer (or engineer) the rules to your advantage. The inspectors and refs will call you on it.

Re: 2nd Most Awaited Q and A Answer?
 

Absent some type of connecting linkage, the two arms would be separate, independently operating appendages. A linkage would force them to operate as one and be in compliance with rule R02. Hopefully.

Re: 2nd Most Awaited Q and A Answer?
 

So, you are assuming that as long as some "connecting linkage," that establishes contiguity between the two protruding arms of the appendage, passes outward, along with the arms, and fully beyond the perimeter, as part of the same motion that extends the arms outward., then this makes them effectively a single appendage.

This implies you are also assuming that two arms joined at their base to a single hinge plate fixed onto the frame, which plate remains permanently inside the frame perimeter, and by which this hinge plate swinging, would both arms be actuated to move IN UNISON beyond the frame periphery, that such a mechanism would be considered TWO appendages, because the the element that establishes their "connecting linkage" (for contiguity) never travels outward along with the arms beyond the frame perimeter.

So if both these assumptions are valid, then the conclusion would be that as long as the appendage's "arms" have a "connecting linkage" which travels along with the motion of these MULTIPLE "arms," which ALL break the frame perimeter, so long as that connecting linkage also breaks the frame perimeter, this connected group of appendage "arms" will be considered to be a SINGLE appendage.

This would make the critical test be whether or not the "connecting linkage" element fully tracks along with the motion of the "arms" and ends up always traveling through the space near the robot such that, along with the arms, it ALSO always breaks the plane of the edge perimeter whenever those "arms" extend beyond the frame perimeter.

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

Actually....no. The test is much simpler. If two appendages which operate independently are connected by some type of linkage so they can no longer operate independently but only operate in unison, they are a legal appendage. That is what I am going for in my submission to the Q&A.

Re: 2nd Most Awaited Q and A Answer?
 

My common sense is being short circuited by the very weak language surrounding the "appendage" definition, and this problem has lasted much too long.

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

Well, when you say "only operate in unison," is that restricted to only their movement for deployment extension beyond the frame perimeter, but after deployment motion completes, can they can perform independent functions for each arm? Or, must they continue to operate in unison performing a single function by their coordinated movements, for as long as they remain outside the frame perimeter?

What if my bridge tilt arm is forked and one side of fork can also grab a ball and return it into the robot. Sometimes it would extend to tilt the bridge, and sometimes it would extend to get a ball. Would this be a violation, even though both arms of the appendage extend outward and return inward "in unison" as you describe?

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

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!!!!!

Re: 2nd Most Awaited Q and A Answer?
 

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

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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).

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).

Re: 2nd Most Awaited Q and A Answer?
 

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

Re: 2nd Most Awaited Q and A Answer?
 

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

Re: 2nd Most Awaited Q and A Answer?
 

I would think the corner of the "zone" would not be a 90 degree angle, but a radius of 14 inches. The extended appendage can not exceed 14"!!!

Re: 2nd Most Awaited Q and A Answer?
 

^This.

It is exactly common sense. The appendage in this case is never more that 14in from the frame perimeter. In my opinion this is what the GDC is going for, and it makes sense (I do not speak for the GDC).

Re: 2nd Most Awaited Q and A Answer?
 

Let me try my hand at this:

The language could be cleaned up (especially in points 3 and 4), but I think this covers all of the situations that have been discussed.

Re: 2nd Most Awaited Q and A Answer?
 

That's a good start. Allow me to pick it apart a little.

• The degrees of freedom language is a good idea, but how do you account for component and assembly flexibility? If I join two things with a bar of aluminum, does that imply 0 DOF? What if the bar is really thin and flexible? (Basically, is there a threshold beyond which you consider something to be a DOF?)
• Maybe you want to describe "crossing" the frame boundary, and mention that "contiguous" refers to the parts on either side of that boundary? (Otherwise, it could be interpreted as meaning contiguous with respect to some other thing.)
• From what parts of the appendages is the relative angle determined?
• Using the centroid is good in principle. However, depending on whether your definition of frame boundary can vary due to robot configuration changes, you might have a uniqueness problem. (Was "frame boundary" meant to be the same as the "frame perimeter"?) Also, unfortunately the centroid is imaginary and hard to locate.
• I assume you understand that the 90° spec you outline is not equivalent to the existing constraint. Also, presumably you mean the smallest angle between them. (And incidentally, isn't 75° a lot like 105°? Why would one be illegal and the other not?)

This is actually the exercise the GDC needs to go through internally (who knows, maybe they do) to settle on verbiage that reflects their intent accurately, and exposes the potential for misinterpretation.

Re: 2nd Most Awaited Q and A Answer?
 

IMO an unconstrained flexible element fails the 0 DoF test because when power is not applied, given the position of any other element (taken pair-wise) that is part of the appendage it is not immediately apparent what position the element in question will occupy. As to whether or not an element is "flexible" (as all elements will have some degree of deflection to them), I feel that this is something to which the reasonable man test can be applied (i.e. an element is flexible if a reasonable man believes that the element was designed to take advantage of its deformation)

I did mean "frame perimeter" when I wrote "frame boundary"; since the frame perimeter must not articulate, I believe this covers your first point. As to the centroid being imaginary, I see no other precise solution that would offer a definite "center" to the robot; if there is a major disagreement between a inspector and a team the centroid can be (albeit with difficulty) be calculated.

The idea was that any part that crosses the frame perimeter must be contiguous with any other part that crosses the frame perimeter, in a pair-wise fashion. A part that "crosses" the frame perimeter is one that is both inside and outside the frame perimeter simultaneously.

The 90° was chosen because barring requiring all robots to be rectangular in shape I see no reasonable way to define the "sides" of a robot in a way that allows for various geometric shapes, while retaining what I believe is the intent of the rule: to allow appendages to extend, but in a relatively narrow direction. Perhaps a better test would involve rotating a 90° cone around the centroid.

Given your feedback (much appreciated by the way), here is a revised list:

Re: 2nd Most Awaited Q and A Answer?
 

This question was just answered in the Q & A system.

"Yes but the contiguous part of the appendage must be outside the Frame Perimeter"

Re: 2nd Most Awaited Q and A Answer?
 

The conservative approach wins again....

Re: 2nd Most Awaited Q and A Answer?
 

...... and light saber test. I read this thread and still not sure about something. If you drew a tic-tac-toe game with center box being the robot and the center squares along the edges being were your app comes out, can the app enter into the corner boxes?

Re: 2nd Most Awaited Q and A Answer?
 

And here is another recent question and new answer which impacts our discussion here:

Q. Will you please either clarify the ‘appendage’ definition, or state the legality of an appendage design with two separate arms that extend beyond a single frame perimeter edge and driven by a single/common mechanism inside the frame perimeter? The related Q&A responses seem rather ambiguous. Thanks.

A. As the other responses indicate, there is no formal definition of "appendage". However, one appendage (as allowed in Rule [G21]) would be one contiguous assembly. The contiguous part of the appendage must be outside the Frame Perimeter.

Re: 2nd Most Awaited Q and A Answer?
 

This would seem to rule illegal all of the ball collection systems teams are making involving cylinders and discs with surgical tubing attached unless all of those pieces of tubing remain inside the framer perimeter at all times as the cylinder spins. Doesn't impact us but it will effect a lot of teams.

Re: 2nd Most Awaited Q and A Answer?
 

Unless the central pipe or part thereof also lies outside the frame perimeter. Right?

Re: 2nd Most Awaited Q and A Answer?
 

As that pipe moves out of the frame perimeter there's going to be a period of time where you have more than one appendage for a fraction of a second. Unless the GDC makes another ruling that would seem to be a violation. I suppose you could build one that only has tubing on one side and a way to stop it with that tubing facing inwards to park but it wouldn't be fun.

Re: 2nd Most Awaited Q and A Answer?
 

I would agree with this assessment. But it would mean that whole assembly would need to be able to be retracted into the robot at the start of a match and then extended for use.

Re: 2nd Most Awaited Q and A Answer?
 

This would be true for any "H" shaped manipulator as well. As you extend the entire appendage out side the perimeter there will inherently be a time period where just the prongs from the H stick out, even if when the H is fully extended it satisfies the contiguous criteria.

-Brando

Re: 2nd Most Awaited Q and A Answer?
 

I've submitted a Q&A on this.

Re: 2nd Most Awaited Q and A Answer?
 

If they had just added three words, it would all be clear(er).
"The contiguous part of the appendage must be outside the Frame Perimeter at all times" (Italics were ADDED BY ME, NOT part of the actual GDC answer!)

If they'd just added those words. Not that I'd WANT those words, but it is STILL "clear as mud".

If you "extend" your "H" shaped appendage so that it is vertical (prongs of H sticking up) until fully outside the perimeter, then flip it down, it might satisfy the "at all times" requirement. Still a pain in the butt.

But maybe they didn't put "at all times" for a reason. Maybe it's OK to briefly have two prongs outside the perimeter. But what if your robot broke at exactly that point and you couldn't get it further out? Penalty! And who defines "briefly"? This is a quagmire and I think the GDC knows it.

Should have had a lawyer on the committee from the 'git go'... it's our job to avoid this kind of ambiguity! (Not that we always succeed.)

Re: 2nd Most Awaited Q and A Answer?
 

By adding that the appendage has to pass the contiguity test outside the frame perimeter the rules are further muddied... as you mentioned..

My opinion would lead to a definition that would simply state that this outside the frame perimeter contiguous requirement should not read at all times but rather should read after deployment.

This would make the Y-shaped appendage legal (as was stated in an earlier Q and A) Presently, given the initial answer for the Y shaped appendage which was "OK" one could only assume that during deployment it was permissible to "lead" with the forks. If forks are ok... then the outside the frame contiguity "at all times" is not consistent... You would have to have a triangle leading rather than a fork. (I would imagine that triangle would not work like a fork...

I would hope that Q and A makes it clear that they really mean "After Deployment"

I know this does not help those teams that were designing a cylinder with little tubing arms sticking out side the frame perimeter... but it would at least clear up the situation...and make the earlier QA answer regarding the forked appendage consistent with the new revelation of "contiguous outside the frame perimeter"

Re: 2nd Most Awaited Q and A Answer?
 

Yes, that ("after deployment") would be perfect! I agree that it would even be consistent with the prior, Y-shaped answer. Bingo!

Re: 2nd Most Awaited Q and A Answer?
 

But, if the "after deployment" section is indeed added then the questions become, what is "deployment" and when is "after." If my appendage interacts with a feild element, a bridge for example, and is then further intentionally articulated to affect the position of a feild element, as many tippers aim to do, am I deploying my appendage, or has it been deployed into action.

To continue, the "after" statement would also allow bending of the rules such that teams could claim their fingered ball roller was continuously being deployed and is thus in exception to needing to be contiginous.

Why can we not just be allowed to extend 14 inches past any one plane projected vertically from the backing of any one bumper section. This rule and the following Q and A have gotten out of hand.

Re: 2nd Most Awaited Q and A Answer?
 

Shouldn't you have to show the appendage(s) deployed at inspection?

Re: 2nd Most Awaited Q and A Answer?
 

It is unfortunate that the semantics have gotten this complicated.

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.

It seems the gisted question is whether "once" refers to a segment of time or a segment of space. Given the question's reference to space in this capacity ("splits" takes place in a specific place as measured in inches, not a specific time), I'd venture that it's the latter. Of course, I don't know.

Perhaps what they need to do is define it as "after deployment, or when it intentionally comes in contact with a Court element (whichever comes first)". This would seem to preclude the potential loopholes above.

Tuba4: Of course; this is true of all appendages.

Johnr: Our current problem is defining what "deployed" means, but much of this call will actually be left up to the Refs in-game under G21, as teams may well have a robot that could meet R02 but doesn't (e.g. has two appendages, and extends both at the same time). The Inspectors also have R02, but the inspection list has yet to be published.

Does anyone remember when the Inspection Checklist usually comes out?

Re: 2nd Most Awaited Q and A Answer?
 

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 :)

Re: 2nd Most Awaited Q and A Answer?
 

I haven't checked this thread for a while.
If the GDC had more thoughtfully considered our concerns regarding the points I was trying to zero in on with my earlier posts (for which I was accused of lawyer-ing the rules), their latest answer might have been more comprehensively clear cut.

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

I wish this were their actual answer. It is much better :P

Re: 2nd Most Awaited Q and A Answer?
 

Wow, i read that completely differently. The answer says ," the appendage". I took that to mean the appendage as a whole and once outside frame it must be one unit.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

i think that perhaps we are actually seeing a response to "don't lawyer the rules"

The rules committee was pushed into a corner...had to make a decision and now (after 3 + weeks) we have that decision.

I doubt seriously if they were going to tell the inspectors that this was the interpretation at the beginning of the season, it was going to be a loose definition of appendage probably.. If they did have that idea at the beginning and never told the teams it would have been a disaster at regionals so I doubt that this was their intention.

By asking all of our questions we have forced them into a narrow interpretation of this rule and now we have to live with it.

I think, now that we have created this narrow definition, it is incumbent on all of us to make sure that ALL teams know about it. (It would seem that this should be done through an update but) Update or not we HAVE to tell all of those other teams that don't follow the Q and A. (Or even sometimes the updates...)

As a community we could easily say that it is all of their responsibility to do this themselves but this would not be gracious. Many teams (especially newer teams) don't look at CD and some don't even know about the Q and A. I don't even think that team contacts are sent an email when an Update comes out any more...

Young teams are struggling just to build something. We need to help them understand the rules so we can all compete together.

I know as an inspector last year I had teams struggle with the bumper rules.
I mentioned the Q and A and they stated they didn't have time to watch it... it was difficult to pour through... this year it is substantially improved but still many teams won't use it..

Let's get the word out...

Re: 2nd Most Awaited Q and A Answer?
 

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

Re: 2nd Most Awaited Q and A Answer?
 

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

Re: 2nd Most Awaited Q and A Answer?
 

I agree what you have here is a common sense interpretation, one that I believe most teams have been operating under for the past 3.5 weeks.

This response seems to completely contradict the common sense interpretation put forth above by JamesCH95. This is what frustrates me when people start saying "don't lawyer the rules, just use common sense". Well, sometimes the common sense of the community and the common sense of the GDC aren't the same, nor should we expect them to be. Different people will always have different interpretations. In this case, since the rule wasn't unambiguously spelled out in the manual, and since Q&A's weren't fully addressed, we're now 58% through the build season and being given a ruling that will significantly alter the designs of many teams. The teams who didn't "lawyer" the rules and used their own common sense are now the ones who will be forced to make major changes.

I can't see any justification for why this rule is being interpreted this way. I'm hoping that this is just a misinterpretation, similar to the issue we saw with the reference plane of the bumper zone earlier this season. If not, a lot of teams are to have to make a lot of changes, and a lot of inspectors are going to be forced to enforce a rule they'll have a very hard time justifying to the teams.

They don't call it the hardest fun you'll ever have for nothing. Just another challenge.

Re: 2nd Most Awaited Q and A Answer?
 

I will be suggesting to my team tonight that we put a retractable cap on our appendage. To be lifted off of the appendage after the joining point has clearly exceeded the frame.

Re: 2nd Most Awaited Q and A Answer?
 

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.

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.

Re: 2nd Most Awaited Q and A Answer?
 

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?

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

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".

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

I zeroed in on this dilemma earlier in this thread, when I questioned how the contiguity test would be applied. My "common sense" told me that any "appendage contiguity test" would ONLY make sense if it was applied EXCLUSIVELY to ONLY those portions of a deploying appendage that were progressively crossing and occupying the OUTSIDE SPACE of the boundary of the frame perimeter.

The only portions of a robot component that can be considered or evaluated as an appendage, are those portions which HAVE EXTENDED BEYOND the frame perimeter, and their contiguity assessment CANNOT consider ANY PORTION of the(se) component(s) that REMAINS INSIDE the frame perimeter -- only what PROTRUDES BEYOND.

The reason that the contiguity test "path" COULD NOT be allowed to be traced crossing back INSIDE of the frame perimeter, is that, since all parts of a robot are normally contiguous to the robot inself, there has to be an imaginary demarcation PLANE to merely establish the concept of discontinuity. It is then in relation to this demarcation plane of the frame perimeter that we can evaluate the contiguity of what has protruded beyond it.

This was how I came up with the lightsaber test concept, that artdutra04 has so nicely illustrated in the image below:



I like the suggestion that no appendage be assessed for contiguity until it contacts the field, field elements, or an item (non-robot) that is in contact with the field or field elements. Otherwise, LEGAL appendages have just become a whole lot less capable than what we thought they could be!

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

Here is the definition of contiguous from:
http://www.merriam-webster.com/dictionary/contiguous

1
: being in actual contact : touching along a boundary or at a point
2
of angles : adjacent 2
3
: next or near in time or sequence
4
: touching or connected throughout in an unbroken sequence <contiguous row houses>

Could we use definition 3 to solve this whole problem. "Next or near" would solve all the problems of not touching when taking cross sections and "in time or sequence" would help with the deployment process as a whole. If the appendage moves all parts touching or not in the same sequence it would be considered contiguous. It seems to me if we have this definition on hand as proof at competition no inspector or head ref would be able to rule against us.

Re: 2nd Most Awaited Q and A Answer?
 

This is what I thought all along...it's pretty obvious to me....

Re: 2nd Most Awaited Q and A Answer?
 

#3 def is more related to temporal considerations with a touch of motion implied. There is a concept of "contiguous motion" that might be applied.
#4 is more related to the connecting physicality of objects assembled together.

-RRLedford

Re: 2nd Most Awaited Q and A Answer?
 

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?

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.

Re: 2nd Most Awaited Q and A Answer?
 

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.

Re: 2nd Most Awaited Q and A Answer?
 

I wonder if the GDC has ever "changed their mind."

From the standpoint of an event volunteer, I hope they do... this ruling really makes no sense...

Re: 2nd Most Awaited Q and A Answer?
 

so the question i would have is this:

Is a human hand an appendage? or is it the fingers? or is it the arm? We can spend all day arguing the points of the question. We'll have to find out week one or in an update. The gnashing of teeth is wasted energy.

Re: 2nd Most Awaited Q and A Answer?
 

Under conventional definition, or GDC definition?

Under GDC definition, when a finger broke the plane, it would be an appendage. When another finger broke the plane, it would be a different appendage if there wasn't a contiguous element (i.e., the palm area) on the outside of the plane. Then when the palm broke the plane, it would be one appendage again. Or you could break the plane with a fist, then expand into a flat hand, and you'd be legal.

There is a slightly different interpretation of one of the Q&As that has to do with exactly which phrase a particular modifier (contiguous, IIRC) applies to. Under the most common interpretation, it applies to the parts of the appendage; it could also plausibly apply to the appendage as a whole (which is what common sense would have it apply to).

Either way, it's a big PITA, and my guess is that IRI will handily forget to check appendage contiguousness if FRC doesn't.

(I have been thinking of a way to make an uncontiguous appendage contiguous for a short time while deploying--it could theoretically be easily applied with a little bit of leftover weight and an hour or so at an event. No design drawings yet, though--I'm still plotting and scheming how to do it.)

Re: 2nd Most Awaited Q and A Answer?
 

I am going to take a stab at summarizing where I think the definition of a legal appendage is at this point. I believe that the only legal appendages at this point would be a U or T shaped one with the bottom of the U or the top of the T pointing up prior to deployment. As the appendage is deployed the bottom of the U or the top of the T, which in both cases would be the contiguous part, would be the first edge to break the frame perimeter. Does this seem like a reasonable, common sense approach to take?

Re: 2nd Most Awaited Q and A Answer?
 

I wouldn't go so far as to say these are the only legal appendages...

If you were to have an H or U or Y shaped appendage you could use two separate motions .. one to move the entire H or U or Y out beyond the frame and then fold it down (when it is outside the frame perimeter).

"Its contiguity extension would preceed its rotary deployment"

Push the Y out beyond the frame and then rotate it down...

think linkages...or two separate controlled motions.

Re: 2nd Most Awaited Q and A Answer?
 

I don't think you have to go that far. An H would satisfy the requirement as long as it was 1) “an appendage is a contiguous assembly that may extend beyond the frame”

Are putting words on the GDC's mouth about the rest if this?

Re: 2nd Most Awaited Q and A Answer?
 

i am not sure what you mean by the last statement but it is pretty clear that if you "lead" with the open part of the "H".. that your design will be illegal

The Q and A answer (see above somewhere) is pretty clear that any appendage must ALWAYS be contiguous outside the frame perimeter.

The contiguity issue is unambiguous...sort of...
I love using those big words...

In case you hadn't read the QA the latest in the ongoing appendage saga....

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. FRC1619 2012-02-02
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A. There is no formal definition of appendage. All pieces of an appendage outside the Frame Perimeter must be contiguous outside the Frame Perimeter.

Re: 2nd Most Awaited Q and A Answer?
 

In other words, we're not putting words in the GDC's mouth. We're taking what they say at face value. Because they don't specify that appendages in the process of being deployed are exempt from contiguity checks, we can reasonably assume that an H or a Y that simply rotates downwards will at some point be discontiguous outside the frame perimeter. Therefore, it becomes illegal at that time, drawing a foul.

Re: 2nd Most Awaited Q and A Answer?
 

so if I add rubber bands to my "H" and attach them to a wire so that as they deploy downward they remain "contiguous" but in functionality they are two separate pieces it would be legal?
So, I would follow the letter of the law and not the spirit of the law? I find that situation indefensible and ripe for an update.

Re: 2nd Most Awaited Q and A Answer?
 

Stringing a rubber band around the prongs of the H wouldn't really make them contiguous. When I think contiguous, I think rigid attachments.