Rule G109

My team has been trying to decide on how to mount our arm on our robot. One of the ideas is to mount it facing a corner of the robot. Today it was brought up that in rule G109 we might not be able to extend it outside of the loading or community zones. The arm would extend over the corner of the bumper, looking at the examples G and H I don’t think that it would work but if it would it could help with our arm. Wondering what others think of this and if it’s legal.

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The rule is that you can’t extend outside the plane of more than one side, aside from MOMENTARY movement from one side to another. So if your robot is explicitly extending over a corner, and isn’t just passing through it, then that is not allowed outside the COMMUNITY (and LOADING?) zones.

A couple ways “around” this are to use a non-rectangular frame, or redefine what a “corner” is. An octagonal frame would potentially allow you to extend out of the “corner”, depending on the design (technically a pentagon would work, but that seems like it would be prone to so many problems).

This is all assuming that your arm will be mounted on a fixed base. A rotating base adds even more options, but also more work.

Thank you for that, I was thinking that it would be illegal and that we would need to mount it towards a face but had not considered changing the frame to create more sides. I don’t know if we have the time to do it but it’s a very cool idea.

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Had a similar discussion early in the season about this as well. As of right now our understanding is that even in the community zone you can only extend out a corner momentarily. Not sure why there isn’t a more explicit diagram in the manual about what the exact extension limit boundaries would be in the community and loading zone. Surprised this hasn’t been asked in the QnA yet.

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In rule G109 it says that there are exceptions one of which being B. A ROBOT fully contained within its LOADING ZONE or COMMUNITY. Would this lead to the robot being able to extend in multiple directions but only when inside of the loading zone or community because that is what I thought it meant with the exceptions


yes you can extend out of multiple sides in those zones, but again the way we understand it is that if you are trying to extend out of 2 adjacent sides your extension limit looks like A, not B or C (again i’m not the gdc and am not 100% on the official rules)

I think that that makes the most sense when looking at the example of robot H in the rules as it shows that it has to stay within the projection of the frame perimeter

Your reading of the rules is correct, you couldn’t extend over that corner outside of the loading and scoring zones.

  1. Is there a more conventional way to mount your arm? A shorter arm or a longer frame? A diagonal arm is going to be a frustrating thing to drive in the best of circumstances.

  2. Do you need to extend the arm outside of the loading and scoring zones? Those are the places where game pieces start and end their cycles. Game pieces are only outside of those areas if something has gone wrong.

  3. Can you put a little diagonal side on that corner of the robot so you’re only extending off one side?

I don’t think this is the correct reading of G109. G109 is the only rule that mentions anything about extending out multiple sides and passing through corners or anything like that. However the end of the rule says:

Exceptions to this rule are:

B. A ROBOT fully contained within its LOADING ZONE or COMMUNITY, and

Therefore the whole rule no longer applies and the only thing restricting your extensions would be G107, so your extension limit would look like C in your diagram.


That’s how I read it as well.

Here’s the overall extension limits:
A) Starting Configuration: No extension other than Game Pieces (H309).
B) Opponents’ Loading Zone or Community: No extension (G108).
C) Your Loading Zone or Community: 48" from the Frame Perimeter, any direction, any quantity (G109, Exception B).
D) Everywhere Else: 48" from one side of the Frame Perimeter, unless you’re swinging from one side to another (G109, Exception C).

For D, the drawing A above captures it, but you can sweep between the two if you’re quick about it (see also “Momentary”, see also G109 Blue Box, picture G).

There’s a “gotcha” lurking in the “create a diagonal side” solution. The arm, including grabber, would need to not be any wider than the length of that side – otherwise you’re back to only being legal to extend it in the loading/community zone. See the diagrams that @Trent posted above. If you take his diagram A and chop a bit off the corner, then you get a third zone extending straight out from that corner, but only as wide as the newly-created diagonal side.

How can we be sure it’s OK for Game Pieces to extend past R102 & R104 in the Starting Configuration? I don’t see this written anywhere in the rules.

From section 1.7:

There are no hidden requirements or restrictions. If you’ve read everything, you know

There are no rules which state that game pieces need to comply with the same starting configuration rules as the robot that’s holding them; ergo, they don’t have to comply with the robot’s starting configuration rules.

Additionally, from Q129 of the Q&A:

There are no requirements that a preloaded GAME PIECE be in the ROBOT’S STARTING CONFIGURATION at the start of a MATCH.

Finally, the rules regarding how you may set up game piece preloads for a match:
From section 8.3:

H309 Know your ROBOT setup. When placed on the FIELD for a MATCH, each ROBOT must be:

G. fully and solely supporting not more than 1 GAME PIECE (as described in Section 6.1

From section 6.1:

Each ALLIANCE may preload 1 CONE or 1 CUBE in each ROBOT such that it is fully supported by
that ROBOT.

The only requirement is that the game piece must be fully supported by the robot.

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