OK, we’ve got a dilemma here, and this may apply to all those folks out there using kitbot chassis.
So, here you go:
We’ve assembled our Chassis for the Narrow Kitbot Configuration. Our design involves an arm that lifts a tetra in front of our robot. Here’s the issue:
If you haven’t noticed already, the narrow kitbot can actually drive within the scoring tetras a bit. This can be good, and bad. In our case, its not such a good thing, because if we attempt to lift a tetra while one of the bottom sections is under our chassis, one of two things is likely to happen:
- The tetra will be damaged/torn apart
and/or - Our robots arm will buckle like never before
So, we derived a solution. We’ve cut two 5x27" “skirts” out of lexan to mount to the front and back of our chassis. These skirts collide with the tetras, rather than allowing them under the chassis. The skirts also provide an opportunity for feedback. The lexan is flexible, so the skirts push inward when up against a tetra. We plan to mount limit switches behind the lexan that allow our bot (in auto mode especially 
) to detect when it is up against something.
This is where things get sticky. According to the rulebook, if these skirts are classified as bumpers, they are not legal for use on our robot, because they only leave roughly .5"-1" of ground clearance (those tetras are so low to the ground!).
If they are classified as “bumpers” they are illegal, as R30 states:
<R30> In order to help reduce the impact forces that the robot will experience during collisions with other robots, teams may add external “bumpers” to the robot. If used, bumpers must satisfy the following constraints:
• Bumpers may extend outside the normal robot starting dimensions (in the horizontal plane) up to 4.” per side
• Bumpers must be located in a region from 2” to 8” above the playing field surface.
• Bumpers must not cause the weight of the robot to exceed the weight limit.
• Bumpers must be removable in order to allow the robot starting size to be easily measured during robot inspection.
• Bumpers must be designed to remain attached to the robot for the duration of the match.
• Bumpers and any bumper mounts that extend beyond the robot starting size may not contain “hard” materials such as metal, wood, or hard plastics. The definition of “hard” is one of common sense (i.e., if you can punch it and not hurt your bare hand, it is ok).
Now, as per the part flowchart, if these are not counted as bumpers, they are legal, but if they are bumpers, the ground clearance makes them illegal. This also poses a safety risk for both the field and other bots using smaller kit-style chassis.
My definition is that they would not be considered bumpers. They are functional, as they provide feedback to our robot. They are also not removable, and they are not intended to reduce impact forces with other robots. They also fit within the size requirements without being removed.
They are intended to protect other robots, field elements, and our robot.
What do you think, are we ok? :o