# Frame perimeter technicalities

My team is having problems getting up the charge station - our robot pushes the ramp up instead of down and gets stuck. One of our solutions is to attach small rollers to the bottom edges of our frame, which should allow us to drive up the charge station without the metal getting caught. However, we aren’t sure if that would cound as a frame extension.
In short, if the rollers are under 1/4", would that incur a frame extension? The rules state that it would not, but it seems they only take into account static, inconsequential objects such as bolt heads. What’s the exact ruling here?

Seems like you answered your own question. At least that’s my understanding.

Yes, and also note (per R101) that the frame perimeter is:

comprised of fixed, non-articulated structural elements of the ROBOT

So no portion of the frame perimeter should be moving during the match, which (IMO) includes rotation.

Remember the frame perimeter is a vertical wall. If the rollers are entirely inside the frame perimeter then they should be OK. If they are at or beyond the frame perimeter, then no.

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Exact ruling:
R101 *FRAME PERIMETER must be fixed.
The ROBOT (excluding BUMPERS) must have a FRAME
PERIMETER, contained within the BUMPER ZONE and established while in the ROBOT’S
STARTING CONFIGURATION, that is comprised of fixed, non-articulated structural elements of
the ROBOT. Minor protrusions no greater than ¼ in. (~6 mm) such as bolt heads, fastener ends,
weld beads, and rivets are not considered part of the FRAME PERIMETER.

On a side note, you could ask the question in the Q/A for a more official answer than Chief Delphi.

Thanks. That helps

What do the mounts/supports for the rollers look like? Where are their outermost edges relative to the rest of the frame and to the rollers? You may want to review how the frame perimeter is determined.

Are you using the team version platform? Did you add polycarbonate to the ramp surfaces?

1678 found that thin poly on the ramps poorly mimicked the expected behavior, we would too easily gouge into the plastic and the effect was what you are describing. We added 1/4" thick sheet to the ramps and the whole tipping the wrong way stopped happening to us. You might also want to consider chamfering the bottom of your drivetrain as we found this also helps.

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