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).