R101 defines the frame perimeter with a taut string. They show a V shaped robot and explain that it has a triangular frame perimeter. R401 says that the bumper must protect “the entire frame perimeter”. So would that V shaped robot need a bumper that crosses that gap along the line of the string, or can its bumper wrap around the inside of the V?
The Frame Perimeter follows the taut string across the gap. Bumpers must be on the Frame Perimeter, whether there’s structure there or not (and there is a minimum structural support later in the bumper rules.
Good question to ask now, as you can design the rest of your robot to keep those bumpers supported.
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We’d like to make a U-shaped cutout in the frame of our bot to make more room for a mechanism to grab notes off the floor. But if the bumper has to run across the outside of that, then there’s no point in doing it. Am I understanding that right? The shape of your robot has to be fundamentally convex?
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Would it be allowable to have a mechanism that goes through that 1/2 inch gap?
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I’m not talking about a gap in the bumper, though. In the V-shaped example they show in the manual, would it be ok to have a bumper that completely lines the inside of the V? Or would the bumper have to close off the open end of the V following the line of the taut string that defines the frame perimeter?
As I understand it:
Since the bumpers need to protect the entire frame perimeter, you cannot have the bumper follow the inside of the V as you need a bumper segment that goes across the opening of the V.
You also can’t close off the open end of the V if the open section is more than 8" wide, as per R410.
Yes, but good luck doing that and making it any sort of structurally stable. Also I would advise against making it exactly 1/2" as any deformation or missed cut could make it larger and be in violation of the rule.
Think of the bumpers as forming a convex polygon around the robot.
The bumpers can NOT follow the inside of that V shaped robot. They must enclose the V, such that bumpers form a triangle.
Likewise, if you picture a U shaped robot, the bumpers can NOT follow the inside of the U. They must enclose the U, such that the bumpers form a rectangle.
One interesting one we saw last year was a team trying to do a T shaped robot. Again, forming a convex polygon, the bumper rules make that a triangle, as you can’t follow the T inwards.
In 2023’s manual, R401 / Figure 9-3 covered these cases of a V-shaped frame, and "NOT A BUMPER"s attached somewhere inside the frame perimeter polygon. Too bad there aren’t elements of that graphic in this year’s manual.
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