What I’m afraid of is that rule says bumper must cover the frame perimeter but blue parts in the picture are not a part of the frame. Blue parts are the stands of the intake arms. We are planning to screw them onto frame. Frame is made of steel, blue parts are 2cm thick tempered aluminium.
Green lines represent the points where bumper will be attached.
To answer your question: as long as the bot (when viewed top down) has frame structure around the perimeter with no gaps greater than 8" (for full wrap bumpers) then you are alright to attach as above as long as it is rigid and changes color easily. I.e. as long as you bumpers locked on well it could be secured with a single fastener (i.e. 2767 in 2016)
My other concern from the picture:
Do the corners of the bot have frame structure around them? It looks like there are only wheels in the corners in the pic and no supporting structure in the corner itself. This would cause issues with frame perimeter and what can extend beyond it.
To follow up on this. If the orange L-shaped sections surrounding the wheels have no structure in them, then you’ve effectively created an octagon-shaped perimeter. Your bumpers would have to follow the diagonals, and there would need to be 6 inches of bumper running on both sides of all 8 corners. The wheels are another problem in that scenario, because assuming they are in the bumper zone, they become part of the definition of the frame perimeter. Wheels are not non-moving parts, so there’s another problem.
We don’t have supporting structures around the corners. What issues would it cause about the frame perimeter?
The issue is the frame perimeter would want to create a clipped corner frame (octagon). This is in theory fine, however the wheel would intersect the edge of the clipped corner. This would violate R410 (as the cutout is greater than 1/4" deep)
You can solve this by taking advantage of what counts as frame perimeter by adding a small piece of thin (1/16 aluminum plate) like so:
All this is going off the image you shared, so I can’t be positive I am understanding correctly. A robot picture top down on a corner would be helpful)
Like many we saw the desire to get the wheels as close to the front & back of the robot, so we put our frame perimeter above the wheels (also helps with getting bumpers with as much ground clearance as legal).
It doesn’t need to be much, just so the wheels are within the perimeter when measuring with a string around the frame and the unsupported deep gaps are less than 8".
Hard to give an exact answer without seeing it in person, but as long as your bumpers meet all the other requirements, that appears to be legal support to me.
how thin is the blue metal?
2cm, but if you are asking the sheet metal itself it is 1cm
Perhaps surprisingly, there is no rule specifying a minimum thickness and/or specific material or strength of your perimeter. The applicable rule is G104 Keep your BUMPERS together. BUMPERS may not fail such that a segment completely detaches, any corner (as defined in R401) of a ROBOT’S FRAME PERIMETER is exposed, or the team number or ALLIANCE color are indeterminate.
I’m not sure I would call 1cm thick material “sheet” metal – did you mean 1mm?
That might not matter. The FRAME PERIMETER must be comprised of fixed, non-articulate, and structural elements of the ROBOT. See R101 and the blue box in that rule for FRAME PERIMETER definition.
We just call it sheet metal inside the team, metal is 1 cm.
I’m not seeing that from your CAD drawing – 1cm thick is as thick as your finger.
Material thickness is not to scale. We just rushed the redesign.
We have had the same issue in inspection this year. We got rid of the tubes in the corners to get the wheels closer to the end of the robot and be able to use 4" wheels. The fix to be legal was adding 1/4" bits of lexan that went to the corner of the bumper so we would have a square frame perimeter.
We passed inspection, but our inspector strongly suggested that we should change those to thick metal as corner impacts on the bumper could cause it to cave in. We are working on these changes for our next event and I would advise you to also have something decently strong there so your bumpers don’t get destroyed.
I would pass it with 1cm metal, tho I would still suggest a stiffener or 2 on each side, so that it doesn’t get bent up and move your bumpers out of the bumper zone.
Also yes @Richard_Wallace and @john3928 there is no rule on what the FRAME PERIMETER must be made out of, but R408.G could be applied to metal that is overly thin and to the inspector a good hit from another robot or into the wall would rip off the attachment system.
must attach to the FRAME PERIMETER of the ROBOT with a rigid fastening system to form a tight, robust connection to the main structure/frame (e.g. not attached with hook-and-loop tape, tape, or cable ties). The attachment system must be designed to withstand vigorous game play. All removable fasteners (e.g. bolts, locking pins, pip-pins, etc.) will be considered part of the BUMPERS.
For thin material/metal R410 could also apply, as that material could be deemed not structure/frame, per the blue box.