# <R12> 72" x 72" Size Restriction

Uhh, yeah. I was one of numerous volunteers to get inadvertently whacked by a tetra in 2005, while standing near the edge of the field. I recall seeing video somewhere of another volunteer actually getting capped, and something similar happened to a robot operator when an arm reached over the end wall and dropped one.

FIRST will continue searching for rules and procedures to keep us from hurting ourselves. However, none of this will substitute for judicious application of common sense.

without a doubt

I don’t think this kind of test would work. The rule states that “a ROBOT may expand up to a maximum width of 72 inches and depth of 72 inches”, not that the robot must fit within such a limit at maximum extension.

If a team were to design a robot with an arm that was mechanically capable of exceeding the limit, but either programatically limited the horizontal extension of the arm or trained their operators to always stay within the limit, it wouldn’t appear to be a violation of <R12>.

This sort of litmus test cannot work this season, as the rules explicitly state that robots are permitted to extended beyond this limit while in their home zone. It’s entirely likely that many robots will have mechanisms that extend beyond 72", possibly even serving multiple functions, and that there’s no comprehensive or accurate way of determining – on or off the field – whether this rule has been violated.

The first one is likely to be the correct reading of the rule. Imagine a referee checking the robot with a 6x6 foot frame - orienting it as needed to fit everything in. The words “length” and “width” would simply refer to arbitrarily oriented Cartesian coord axes.

I’ve been doing a little trig, and a little Paint.
http://img19.imageshack.us/img19/7293/geogo6.gif
The square is the bounding box, the rectangle is the robot. The diagonal of the box is 72√2, the length of the robot is 38, and the wasted part of the diagonal in the lower left is 14. As such, I calculate that an object of negligible width can protrude (72√2)-38-14 = 49.8 inches from the front of a standard size robot. Is this consistent with our current interpretation? Does this make sense in the spirit of the rule?

No, this is NOT within the spirit of the rule as I understand it. The robot in your drawing clearly has a length (front to back) in excess of 72 inches. However, with the current wording of the rule, it would be OK if your robot was round because the “front” of the robot would be poorly defined.

It will be interesting to see how this is handled in the updates and the Q&A. It won’t be officially answered anywhere else.

(PS, Good to see ya again Joey!)

That whole line was super confusing . As far as I understand we can only transform in width and length in the home zone but when we’re out on the field we can go as high as we want within the restriction of the cieling. Is that what everyone else got?

When in the home zone, you are allowed to expand as large as you want (provided you are still entirely in the home zone). When outside of your home zone, you may expand to a maximum of 72" “width” x 72" “depth”.

I’m leaning toward jgannon’s interpretation. I’ve already posted the question to the Q&A, so we’ll see what the official word is.

I’m for jgannon’s interpretation because BillP’s reading means that the front and back of the robot is arbitrarily defined by someone other than the team. In that case specifically to the team’s disadvantage. At the very least, the team should be able to decide which way is what. Saying that it would be okay on a round robot is just semantics and silliness. What if I have slightly bowed out plexi on all sides of my robot? There’s no flat surface to attach the axes to there either.

I don’t think that we can define the length of a robot in any manner other than the bounding box approach above. Though many robots do have a preferred direction of travel (which might be assumed to be the length axis, with the width axis perpendicular to it), there are numerous robots where no one axis is inarguably the length—the omnidirectional drivetrains, for example. Similarly, the bounding box model is what’s used to check the robot footprint at inspection. A robot can do what it pleases within the box, but it has to fit.

While we’re on the subject, front and back are not especially meaningful, except that to comply with the rules, teams will arbitrarily designate them (e.g. to place the diagnostic light).

Actually width and depth are clearly defined in most situations by <R07> (see chart on page 8 of Section 8). The width is your 28" dimension, and depth is your 38" dimension. Unless one of those dimensions is rotated in your starting configuration, I doubt it would be allowed to be rotated later.

i might be wrong, but that definition only is for the starting configuration of the robot. Look at this example. A robot expandes to the full 6x6 square. it has an arm that is in the bottom left corner and ends in the top right. how is that any different from making a square robot with that length arm and making it fit diagonally.
correct me if im wrong.
-coop, team 1717

that reminds me of the joke about the boy with the fishing pole trying to get on the bus. The bus driver said his five foot fishing pole was too long, you can only have something four feet long on the bus. So, the boy visited the garbage cans behind some stores and found a 3 foot by 4 foot box and put the fishing pole in it, and was let on the bus.

i really belive that the 72 in limit only applies to the footprint, that means that arms could extend farther.

the arm cannot extend beyond the footprint. the footprint=a shadow of your robot straight below it.
-coop, team 1717

…at noon, on the Equator.

Edit: On the solstice.

And the Q&A comes through. The answer is that the robot must fit inside a 72" x 72" x infinity virtual box at all times. So the diagonal trick works. I suppose still under question is whether it must be designed mechanically to never exceed the size, or whether it can be a driver/controls thing.

:yikes: :yikes:

Did I hear someone mention flux integrals ?! hehe

We had to back out of the West Michigan Regional due to lack of \$\$ - now we’re going to have to travel to the Equator?
FedEx ought to love that one.