Can someone help me understand the frame perimeter rule (eg. “minor protrusions” under 1/4" under R01-2)?
Our robot will be using C channel. We will have a lower level frame for mounting wheels and directly above an upper frame (also C channel) for mounting bumper, manipulator, etc.
Gusset plate - Would a gusset plate (1/16" steel) and bolt head that combined are less than 1/4" be legal according rule R01-2? We would like to use steel gusset plates on the exterior of our frame to create a rigid connection between the lower and upper frame. If the C Channel (that defines frame perimeter) is oriented so the open part of the C is facing the interior of the robot, the exterior surface makes a good surface to attach the gusset plates on both upper and lower frame.
2.C Channel Orientation - If gusset plate is not allowed on exterior of frame, would a C Channel oriented with the open section facing the exterior of the robot (bumper would be mounted to this) be legal?
It sounds to me like the gusset plate would define the Frame Perimeter.
Remember that “Frame Perimeter” doesn’t mean “the perimeter of the piece of the robot you call the frame”. It’s specifically defined as the polygon defined by the outermost set of vertices of the robot within the Bumper Zone. If your gusset plate is between 2 and 10 inches off the floor, it’s going to contribute to those vertices.
I agree with Alan. It sounds like the gusset plates are behind the bumpers, so they would define the frame perimeter and the slight protrusions would be allowed in the bumper zone.
Two things to keep in mind:
Make sure the gusset plate + bolt heads don’t push the bumpers out enough that you have more than 1/4" gap between the bumpers and the c-channel along the rest of the bumper length, or the bumpers will be considered unsupported and need support every 8 inches. If they do, you are allowed to place small relief areas in the bumper plywood to clear the bolt heads.
The bolt heads can protrude beyond the frame perimeter, but they still have to be inside the maximum allowed dimensions of the overall robot (they still have to fit in the sizing box).
Also realize that the dimensions of everything that remains after you take off your bumpers (including minor protrusions of things fastening your gusset plates) must fit in the 28x38 sizing box. The minor protrusions clause relates to the bumper/robot interface, but gives you no grace on the 28x38 size limitations.
This is the reason most teams size their frame perimeter at 27x37 or so maximum. This also helps for cases where the upper parts of your robot which may be wide and ‘out of square’ since it has to fit inside the box also.
Thanks. Our frame is 1" shorter than maximum allowed (eg. 27" x 27").
Didn’t want to start cutting based upon an incorrect assumption (eg. gusset plate and bolt head less than 1/4" allowed on exterior of C channel) and find out our robot doesn’t pass inspection.
We’ve built a subframe spaced off of the main frame with aluminum tubing as spacers/standoffs and 1/4" threaded rod holding it together. Sorry I don’t have any pics, but it’s strong, easier to cut than gussets, and the frame will remain flat to make it easier to mount bumpers.