Is it legal??

Competition Rules/Strategy
#1

Hi… our robot has Mecanum drive and the metal pieces that attach it to the profiles have fasteners that are attached in the outside of the profile… it is “outside frame perimeter”… now… if you measure the FP as the length from the end of the fastening bolt to the other (I mean- if I measure the length including the “outside FP” parts as my new FP) it is still withing the 28*38 limit… my question is- is it legal? because the guys in our team said something about not having anything outside FP inside our bumperzone… but maybe the FP is measured along w/ the bolts and then it is fine… I just don’t know… I attached a picture of the metal part holding the wheel, for you to understand…
what can we do to make it legal until CMP inspection? I’ll mention that we do not have enough time to make new ones…

Thanks!
Team Artemis #3083

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#2

The FRAME PERIMETER is defined by the extent of the robot frame, excepting minor fastener protrusions, within the BUMPER ZONE. Such protrusions in the BUMPER ZONE are exempt from the rule prohibiting any part of the robot from extending outside the FRAME PERIMETER. Protrusions outside the bumper zone are not exempt from the rule. Your design has bolt heads outside the FRAME PERIMETER and thus breaks the rule.

To fix it quickly, make your FRAME PERIMETER bigger so it encompasses all the protrusions. Add a thin strip of some solid material to the outside of your robot where the bumper will fasten.

#3

No, it’s not legal. The bolt heads that hold the bracket to the frame, behind the bumper, are legal, but the bolt head that holds the wheel to the bracket, is not legal. And the way the bracket is attached to the frame, it’s not quite legal, because the FRAME PERIMETER is defined by the largest part of the frame, which is the bracket, and the frame rail needs to be out a bit further (the thickness of the bracket) to be legal.

you could add a shim to the frame between the brackets, this would make the frame itself be as large as the FRAME PERIMETER.

And you might be able to use flat head bolts for axles, to keep the bottom of it legal.

The bolt heads that stick out of the FRAME PERIMETER within the BUMPER ZONE are legal, and you can just pocket the bumpers to fit over them. I’m assuming that these bolts that hold the brackets to the frame rail are more than 10 inches, and less than 16" above the floor.

#4

May,
If the top of the wheel bracket is in the BUMPER ZONE then the FRAME PERIMETER is set by the bracket. If the top of the wheel bracket is below the BUMPER ZONE then the bracket, rivets and the bolt head are all outside the perimeter. If your total robot dimensions are still less than the 28 inches (71.12cm) by 38 inches (96.52cm) then you may be able to correct the condition with the addition of 1/4" plywood attached to the frame in BUMPER ZONE. The FRAME PERIMETER will then be set by the dimensions of your frame plus the thickness of the plywood.

#5

Al-- if they add 1/4" shims to move the bumpers out, then the front and rear bumpers will be too short by 1/4" at each end, will that cause problems? What’s the inspection tolerance on bumper lengths?

#6

I think inspection’s tolerance on bumper lengths is pretty high for this very reason. I know mine was at Lone Star.

There may be another option if these bolt heads are your only protrusion outside the bumper zone. You may be able to use a rivet nut in the outside bracket and thread your bolt into this rivet nut. This may be quicker and easier than increasing the frame perimeter with plywood or other material. It would also leave your current robust bumper-frame connection intact. See this McMaster-Carr link for an example of some rivet nuts:

McMaster-Carr Catalog Page 3269

Only downside is you would have to modify the length of your axle spacers to accommodate the length of the backside of the nut. And you’d probably have to shorten your axle bolt slightly.

#7

There is no tolerance on the bumpers. The tolerance on the pool noodles depend on where they have been stored and can vary almost 1/2". Our test is… can a robot encounter a hard part in the corner if it runs into the other robot.

#8

Al,

I think Jim was questioning the inspectors tolerance for full length bumper coverage of the frame perimeter. If there’s zero tolerance for extending past or coming short of the frame perimeter, it’s impossible to use a previously legal set of bumpers on a robot with an increased perimeter. This would require teams to reconstruct their bumpers even if the frame perimeter is increased by 1/8". That’s a lot of lumber and time for 1/8".

Your second answer seems to get to the point of the question, but doesn’t mesh with your declaration of zero tolerance on bumpers. So the question remains, in slightly different form:

Will inspectors be looking for full frame perimeter coverage by the hard bumper parts, or will they be looking for adequate corner protection using the test you describe?

#9

Kevin,
Sorry for the misunderstanding. There is no stated tolerance for bumpers not “zero tolerance”. As stated in the first paragraph of R07…
The BUMPER location and design have been specified so that ROBOTS will make BUMPER-to-BUMPER contact during most collisions. If implemented as intended, a ROBOT that is pushed against a vertical wall in any NORMAL CONFIGURATION will always have the BUMPER be the first thing to contact the wall.
A team that is required to add 1/4" plywood and has constructed the bumpers as shown in the figures included in R07 (in particular fig 8-3 and 8-4) should have no trouble achieving the statement made in the first paragraph of R07.
The protection of the FRAME PERIMETER does not include hard parts…
A. BUMPERS must provide complete protection of the entire FRAME PERIMETER of the ROBOT (i.e. BUMPERS must wrap entirely around the ROBOT).
Bumper rules are confusing, you heard it here first.