Bumper Design

[Tristan Lall]

Originally Posted by engunneer

Hinges can be tricky, as far as inspection goes. in 2008, we used hinges to hold our smallest pieces on (WAY less than 8", back then it was legal), and it took some convincing that they were mounting hardware. It would have hurt to redesign the bumper mount in the pits.

I'd like to get inspector opinions on hinged bumpers. (To be absolutely clear, not Articulating bumpers, just bumpers connected together at the hinge to make them easier to fold around the robot.)

The first thing to watch out for is whether those hinges may be counted as part of the bumper, part of the main robot itself, and/or a separate thing. (The rule refers to "any fasteners and/or structures that attach [bumpers] to the ROBOT".) The rules are ambiguous on this point, but I'd tend to give a team the benefit of the doubt if they interpreted the rule in either of the first two ways.¹ Confusingly, "removable fasteners" are explicitly part of the bumpers.

A related issue is whether the bumpers are part of the robot—this is complicated and annoying because of the different senses of the word robot, but once again, given the ambiguity, I'd give the team the benefit of any reasonable interpretation.

The current rules call for "a rigid fastening system to form a tight, robust connection to the main structure/frame [of the robot]". Many sets of hinges could satisfy this, installed correctly. It doesn't have to be a specific type of mounting hardware anymore (threaded fasteners were once specified).

With regard to bumper articulation, I interpret that as meaning that to pass inspection, and when on the field, articulation must be prevented. However, I reject the notion that bumper articulation (e.g. via hinges) during assembly of the robot is prohibited. (By definition, every robot is illegal when you're not finished installing the bumpers.)

¹ If you rule it legal as part of the robot or bumper, it counts toward that assembly's weight and size. Inspectors often need latitude to rule it one or the other on a case-by-case basis, to avoid frame perimeter and bumper hard part surgery.

[engunneer]

Originally Posted by Tristan Lall

[snip]
(The rule refers to "any fasteners and/or structures that attach [bumpers] to the ROBOT".) The rules are ambiguous on this point, but I'd tend to give a team the benefit of the doubt if they interpreted the rule in either of the first two ways.
[snip]
The current rules call for "a rigid fastening system to form a tight, robust connection to the main structure/frame [of the robot]". Many sets of hinges could satisfy this, installed correctly. It doesn't have to be a specific type of mounting hardware anymore (threaded fasteners were once specified).
[snip]

That's just it. Since they attach bumpers to other bumpers, it could be argued that they are not "fasteners and/or structures that attach [bumpers] to the ROBOT"

I like them for keeping the bumpers together in more complicated bumper setups. I haven't used them as such since 2008, though.

[Al Skierkiewicz]

Using hinges to hold bumper sections together at a corner is an acceptable method and the hinges and pins must be weighed with the bumper. Using this type of hardware keeps adjacent sections together especially if you are only using the minimum bumper sections at the corners of your robot.

[Taylor]

We've used K-Botics' reversible bumper design for a couple years and found it to be very easy to use at competition. They do require the talents of a good seamster (androgynous version of seamstress?).
AndyMark now offers an entire bumper kit as well as just the hardware to fit over the C-Channel if you're using kitframe or something like it.

[2348humanplayer]

Our robot is made out of extruded aluminum for the chassis. We slide bolts into the front and side, then put a piece of angled aluminum on the back of our bumpers. We slide the things on with the right colors, then use home-made long bolts with a hexagon head, tightening it down with ratchets. They have never come off.

Another hint, to save time with swapping bumpers one year, we made bumpers with a flap in the middle. If we were red, it was one way. When we went to blue, we simply unvelcroed the flap, and put it to the other side, showing blue.