Bumper Dimensions Question

[Mac Generals]

If 2/3's of the robot has to be covered with bumpers, is the hitch opening inclusive in the non-bumper area measurement?

Responses will be appreciated.

[Alan Anderson]

I'm not sure I can parse the question with enough confidence to give a simple yes or no response. The bumper only covers the part of the robot that it...covers. Is that a good enough answer?

[SuperJake]

The bumper zone that is void due to the presence of the hitch counts against your bumper coverage. The maximum coverage you are able to make with the bumper is:

Your Max Possible Bumper Length = (Robot Perimeter) - (Open zone for hitch)

So the max required bumper coverage needs to be:

(Required Coverage) = [2*(Robot Perimeter)]/3

If your bumper length is greater than or equal to (Required Coverage) you are good.

I think this should just about cover it.

[Jon Stratis]

This is indeed an important question to have answered...

From the manual:

BUMPERS – Bumper assemblies designed to attach to the exterior of the ROBOT within the BUMPER ZONE, and constructed as specified in Rule <R08>. BUMPERS are excluded from the weight and volume calculations specified in Rule <R11>.

<R08>[...]
A.
BUMPERS must be built in segments, with a minimum length of six inches, and a maximum length that does not exceed the maximum horizontal dimension of the ROBOT.
I.
BUMPERS must protect all exterior corners of the BUMPER PERIMETER (see Figure 8 - 2).
[...]
K.
BUMPERS must protect a minimum of 2/3 of the BUMPER PERIMETER. Teams are encouraged to maximize the area of the ROBOT protected by BUMPERS. But up to 1/3 of the BUMPER PERIMETER may be unprotected to provide flexibility in design options.

From Team Update 1:

BUMPER PERIMETER – the polygon defined by the outer-most set of
exterior vertices on the ROBOT (without the BUMPERS or Trailer Hitch
attached) that are within the BUMPER ZONE. To determine the BUMPER
PERIMETER, wrap a piece of string around the ROBOT at the level of the
BUMPER ZONE - the string describes this polygon. The BUMPER
PERIMETER may extend up to, but cannot exceed, the maximum ROBOT
volume constraints defined in Rule <R11>.

So, from these quotes we know the following:

1. the trailer hitch is not part of the bumper.
2. The bumper perimeter is the polygon formed by the outer-most set of vertices on the robot - basically, pretend any cutouts aren't there for these purposes.
3. Bumpers must protect 2/3 of the pumper perimeter, including all exterior corners.

So from that, i think it's safe to say that the hitch area does NOT count towards the 2/3, as the hitch is not defined as a bumper.

Some additional facts: if your bumper perimeter is the full 28x38 allowable, you're total bumper perimeter length is 132 inches. 2/3 of that is 88 inches. This means you can have 44 inches of your perimeter uncovered in this example - most likely enough to allow most of one side to be uncovered, plus the trailer hitch on another side.

Remember, each corner has to be covered, and each bumper segment has to be a minimum of 6 inches long - with a normal rectangular robot, covering the corners alone will account for 48 inches of bumper.