# <R12> 72" x 72" Size Restriction

Outside the home zone the robot can expand to max of 72"l x 72"w and unlimited height. Do you think 72" this includes temporary expansion like and arm?

Where the arm might stick 4 or 5 feet outside the robot to place the top tube?

Im not exactly sure i believe it does include it, but i would e-mail first and as for sure, if you find out please share.

It almost certainly means anything for any amount of time. What should really get you thinking is if it only means you should be able to fit your robot inside a 72" x 72" area at all times, or if there are some sort of defined x-y axes on your robot that fix the orientation of the square.

That is to say, if you only have a pole sticking out the front of your robot, can you assume the pole is extended along a diagonal of that square and is limited to something like 90"? Or do the edges of the square have to be parallel to the sides of your robot and you’re limited to 72"?

Does this also apply for the endgame?

It doesn’t apply if you’re in the home zone. You can have a length as wide as the playing feild as long as you stay inside the playing feild.

You DO realize that 72 inches is equivalent to 6 feet. Does that answer your question?

:rolleyes:

But the question was “Where the arm might stick 4 or 5 feet outside the robot to place the top tube?”

38 inch robot plus 60 inch arm equals 98 inches which is more than 72 inches.

Last year you could not extend higher than 5’. If you had a 4’ 6" bot that had a door on top that was 1’ long and it rotated past the 5’ limit when opening you would be penalized.
This year I see a 72" L x 72" W x infinite high box and if you extend out of this box you will be penalized. Even if it’s only for a moment.
Just my \$.02 YMMV

R12 is very clear. They define a “Box” 72"x72" of which the diagonal is more than 101"
But, if the arm swings out of the box, you risk being panelized. I don’t know if this will be an inspection item this year. The sizing is already complicated with the different classes. The Refs may have a way of measuring on the field.

Try designing a round robot using omni wheels. It will be very hard to define the width and depth axis.

I guess the big problem is with and arm while its lifting a ringer from the ground robot will normaly break that 72" plane for a brief amount of time and then return to within the 72" rule. To stay within the rule your arm would have to retract the arm back in towards the robot before extending out again. I think the intention of the rule is to stop huge robots roaming around the field and not to limit arm design. But, thats question I’m trying to find out.

I honestly cannot wait to see the refs out there with tape measures trying to see what the invisble 72" box is, and when a robot extends out of it. Honestly this seems quite difficult to enforce if what were talking about is the correct interpretation.

If the arm is built so that it’s pivoting mount is at one end of the robot, and the arm is less than 72" long fully extended, you’ll be ok. Consider making the arm so that it only can pivot up and down, it cannot swing sideways (or not very far sideways). A 66" long (total extended length) arm/hand mounted on a 56" high mast at the “back” of a robot, would be able to reach the floor and also score high ringers, I think. Make some sketches, see how the geometry works. There seems to me to be no need to make the robot extend further than 72" in length/width to perform it’s task.

I can seen Robot Inspectors doing exactly that, before your robot ever gets to the field. An extra long arm is a potential safety hazard to people near the field boundary, such as referees, emcees, announcers, field resetters, etc. To protect those people, the Lead Robot Inspector has discretion under <R112> to keep any robot off the field, even for practice, until it has been brought into compliance with the rules.

I also can see this, but there are many different orientations of robots. This also severely limits the types of arms you can make, articulation will require some thorough calculations.

The rules are simple. Your robot may, during normal play, not exceed 72" X 72". Use your GP, stay within the confines of the rules, don’t try to bend or break these rules and everything will be fine. Yes, some rules make the game hard - that’s the point! With each limitation comes a new challenge, another opportunity to show off your team’s ingenuity.
Personally, I would hope that refs would never have to whip out their 72-inch measuring sticks - if the robots are designed respectfully within the given boundaries, there won’t be any problems.

The 72" rule is not an unreasonable restriction and may help you to a more stable arm design.

Again, my only question is if it’s a 72"x72" box you have to fit in, or if you paste something on your robot that says “72” this way, and 72" that way."

I expect the inpsection checklist will have a line item corresponding to <R12>. The test will probably be to place the arm or extension so that it is at its maximum reach, then verify that the robot still fits within the 72" wide x 72" deep limit. Of course, passing this test will not ensure that an arm is legal. Safety is always the paramount concern, and <R03> clearly says that an otherwise-legal device on a robot can be disallowed if, in the judgement of the inpsectors or referees, it poses a hazard.

i think this rule is good, arms could get out of control…but then again this is FIRST

I would surmise as much, but I’m going to ask the question anyways. I’ve seen enough official interpretations counter to my instincts that I feel safer just checking.