R3 20" rule
 

After watching Suffield and some of the videos from New Hampshire, teams have different interpretations of the 20" outside the frame rule.

How do you define the 20" extension?

Re: R3 20" rule
 

Measure the horizontal distance from the edge of the extension to the nearest point on the frame perimeter. Doesn't seem all that difficult...

Re: R3 20" rule
 

How so? How did they see it differently?

Re: R3 20" rule
 

I'd like to know too. I thought the rule wasn't ambiguous and was pretty clear. Is there more than one way to interpret this rule?

Re: R3 20" rule
 

There's a good drawing of this on the frc-manual site. To accurately depict it, think of tying a string to the bumpers, able to move with 0 friction around the bumpers. cut it to 20 inches. That is the maximum external allowance!
That should get you close to the drawings provided!

Re: R3 20" rule
 

20" total or 20" on all faces of the frame?

This is the video I am referring to YouTube

Re: R3 20" rule
 

I understood it as 20" on any face with as many extensions as you want. Which is what I believe most people understand it as.

Re: R3 20" rule
 

The rule says "a ROBOT may not extend more than 20 in. beyond the FRAME PERIMETER (see Figure 4-2 for examples) (see G24),"
It doesn't say a total of, it says up to 20 inches beyond the frame perimeter, with no additional restrictions. The vertical extension has an additional 6 inch cylinder restriction written into the rules.

The image also shows a 20 inch box around a robot. It is all the way around, if you were only allowed 20 inches total, that box would be incorrect, it would only extend out 20 inches on one side.

To go a bit deeper into FIRST game history, there was the year that you could extend one thing out past the bumpers. Teams built a single unit arm that came outside the bumpers as individuals and were not joined outside the bumpers until fully extended. Teams were connecting the ends with string to have their mechanisms be legal. It was a mess and a headache, and FIRST does learn from mistakes and issues in the past.

Were there any head refs/lead inspectors/GDC members at the event that commented on this?

Wetzel

Re: R3 20" rule
 

Since we are not using 20" on one side can we extend to 40" on the other? :confused: :]

Re: R3 20" rule
 

No...think of it this way: Draw your frame perimeter from above, then "offset" or project that perimeter 20 inches farther out (perfectly concentric with the frame perimeter). That offset is your "extension zone".

Re: R3 20" rule
 

Here's a quick* example. The inside shape is your frame perimeter and the outside shape is your extension boundary. As long as you stay within the extension boundary, you're fine.

*112" rule was not taken into account while making frame perimeter.

Re: R3 20" rule
 

From the Q&A:

https://frc-qa.usfirst.org/Question/...ly-at-one-time

Seems pretty straight forward to me...

Re: R3 20" rule
 

This isn't totally correct. The 20" is with regards to the frame perimeter, not the edge of your bumpers.

Re: R3 20" rule
 

I have a question concerning weaher its just 20" form the side or weather that 20" also counts for the corner... rather than the 28" that would be found using the pothagorian therium...

Re: R3 20" rule
 

It's 20" to the closest point on the robot. So the 20" would go diagonally to the corner, not perpendicular/parallel to the sides.

Re: R3 20" rule
 

If I understand correctly, you want to extend into the corner such that, looking downward on a rectangular robot, the furthest point is 20 inches in both the X and Y dimensions from a corner of the robot, leaving it 28" from the corner itself, measured on the diagonal.

Again,

Figure 4-2 also clearly shows rounded corners for the 20" - you can NOT extend 28" into the corner, only 20" from the nearest point on the frame perimeter.

Re: R3 20" rule
 

How does this figure, taken from the manual, not answer most of the questions in this thread? This rule seemed pretty cut and dry to me.

Re: R3 20" rule
 

The technique I saw being used for checking this at the LaCrosse WI week 0 event may be helpful.

Hold a plumb bob* so that it touches the furthest reaching (or suspect) point of the extension. If the horizontal distance from the string to the frame perimeter (where the bumpers attach) is > 20" you have a problem.

The plumb bob is also useful to assure that the starting configuration is legal and that everything is inside the frame perimeter

* a free hanging weight attached to a string to produce a vertical line

Re: R3 20" rule
 

It's pretty simple. If you were to draw an outline of your frame perimeter, then you would draw another profile around it offset 20" from your frame. If you had a square frame, the corners of this outer profile would be rounded with a 20" radius. You may fill up this entire outer profile with extensions if you want, but you can't go past it.
For example:
Attachment 16308

Re: R3 20" rule
 

The only issue I have with that image is that it's nowhere near to scale. 20" means you can almost double the short dimension of the kit frame in both directions.