R3 20" rule

[JohnBoucher]

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?

[Jon Stratis]

a ROBOT may not extend more than 20 in. beyond the FRAME PERIMETER (see Figure 4-2 for examples)

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

[TheKeeg]

Originally Posted by JohnBoucher

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?

How so? How did they see it differently?

[magnets]

Originally Posted by TheKeeg

How so? How did they see it differently?

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?

[yash101]

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!

[JohnBoucher]

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

This is the video I am referring to YouTube

[notmattlythgoe]

Originally Posted by JohnBoucher

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

This is the video I am referring to YouTube

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.

[Wetzel]

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

[FrankJ]

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

[Qbot2640]

Originally Posted by FrankJ

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

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".

[Ty Tremblay]

Originally Posted by Qbot2640

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".

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.

[Jon Stratis]

Originally Posted by JohnBoucher

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

This is the video I am referring to YouTube

From the Q&A:

Q. How many directions can you extend 20 in. horizontally at one time?

A. Infinite.

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

Seems pretty straight forward to me...

[Brandon Zalinsky]

Originally Posted by yash101

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!

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

[N91L]

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...

[notmattlythgoe]

Originally Posted by N91L

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...

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.