CINDERELLA 1942 FRC Robot Reveal, 2023 Season: The Road Runner

Cinderella proud to present the Road Runner


Looks sweet. Seems simple and effective.

You may need to review the bumper/frame rules before your first competition. I don’t think that bumper shape is quite compliant.


Love the simplicity of the design to get all but L3 cone scoring with a single degree of freedom!


What rule do you think that the bumpers do not comply?

The concave corners I believe would fall into the “Not a bumper” category.

Because they are “not a bumper” they don’t support the corner adequately.


I believe to fix this the frame shape (and bumpers) would have to change to something more like this:


I could be totally wrong (I am no rules authority). I just read the rules to say concave bumpers are not allowed like that.


It is still allowed. The only question is if it classified as a “bumper” or is it part of the frame and needs to be weighed as such.

I would argue that is the shape of their frame is not really what the rule makers were talking about in that particular rule.

The other problem is R401. Since it’s not a bumper. It doesn’t protect the corner.


To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT
(excluding BUMPERS) at the BUMPER ZONE described in R402 and pull it taut.
The string outlines the FRAME PERIMETER

A string would not follow that path and therefore it is not the frame perimeter. The image above would define the frame perimeter. The bumpers must be on the frame perimeter (and backed by structure).


If those lengths are 6" wouldn’t it be a moot point, since 6" of the corner is covered.

no, those are not on the frame perimeter and therefore don’t count as bumpers.

Then I am confused about the shape of their frame perimeter. If 5(6) + x + y + z =120" isn’t that a legal frame perimeter? No matter the shape? And as long as 6" of each corner is covered isn’t that a legal bumper?

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No. See the definition of frame perimeter cited earlier in the thread. The perimeter is defined by a taut string wrapped around the bot. Uncovered openings or gaps in the perimeter are permissible as long as they are 6" from an exterior corner as defined by the string.

A star shaped robot with each flat piece being 10 inches would have a geometric perimeter of 120". But by FRC rules, the perimeter is defined by lines connecting the points.

But this robot would not be an FRC legal shape, even if all the sides had little bumpers covering them.


Their frame perimeter is actually bound by the yellow lines (see below). This in the blue box under R101.


Bumper rules get rather weird for robots that aren’t rectangles.

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Good to know. We’ve never had a concave shape, so I’ve never thought to hard about it lol

So my new equation would be 6 + 2[(6)sqrt(2)] + x + y + z = 120 would be legal?

Not sure I follow your math, but the way the robot inspectors check is by taking a fabric tape measure 120"long and wrapping it around your robot. If you design keeping this in mind, you’ll be good.


Yes, this math checks out.

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Got it, and thank you for clarifying the information about the string. I never looked at that part of the frame rule close enough.

Also, assuming the measurements are correct from the drawing above. the hypotenuse of a 45-45-90 with two sides = 6 would be 6(sqrt(2))

6 + 6(sqrt(2)) + 6(sqrt(2)) + x + y + z = 120
6 + 2[6(sqrt(2))] + x + y + z = 120

But is those measurements are correct, could a bumper be made to comply with the 6" corner requirement?

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I’m not acquainted with the bumper rules so not sure about the 6" part, you’d have to read the manual. But by the definition of the FRAME PERIMETER being a taut string wrapped around the robot that must not exceed 120", then your equation works with the diagram you gave.

Just for reference, here is the relevant rule:

They specifically show a case in the blue box with a concave frame shape where the frame perimeter “shortcuts” the concave portion to form a convex polygon.