Bumper Rules on a U Bot Chassis

[ICE_Bear]

Wouldn't you just have to cover the entire piece that IS there? per R19

[MrBasse]

Originally Posted by ICE_Bear

Wouldn't you just have to cover the entire piece that IS there? per R19

Read the sentence just before the one you are thinking of in R19 and you'll see why you need at least 8" covered.

[GaryVoshol]

That's not how "side" is defined. The side is from outside corner to outside corner, including any gaps that happen to be in that side. See ROBOT FRAME PERIMETER C (lower left) in Figure 4-3. The FRAME PERIMETER follows the black line around the ROBOT, including the portion spanning the gap. It is marked "NOT OK" since that bottom "U" is less than 8 inches.

[ICE_Bear]

That was labeled "NOT OKAY" because the corner wasn't covered, not because it was less than an 8" piece of the side.

Since it's our chassis piece that's only 4.5 inches long, wouldn't each individual piece be a side?

[David Brinza]

Originally Posted by ICE_Bear

That was labeled "NOT OKAY" because the corner wasn't covered, not because it was less than an 8" piece of the side.

Since it's our chassis piece that's only 4.5 inches long, wouldn't each individual piece be a side?

There are two "NOT OK" labels for Figure 4-3 C - one for an uncovered corner, the other for a segment <8".
You are receiving replies from experienced mentors and robot inspectors, you should consider how to address your design issue. If you are not satisfied with the responses from CD, you should post on FIRST Q&A for official clarification.

[Boltman]

Its fairly simple to determine what size bumpers you need.... use walls and string

Place your robot against wall (without bumpers) that defines a side THEN for each side at least 8 in. of BUMPER must be placed on each side of each outside corner. IF a side is less than 8" entire side must be covered.

So for a U shaped bot the front side would require 8" bumpers per front corner. Thats assuming traditional U-shape with two front corners.

For odd shapes... or to verify corners

Simply wrap a string around the bot (in bumper zone)..any corner of that string shape (frame perimeter) needs an 8" bumper per outside corner side. So its hard to get around 8" rule even with very unique shapes. Either each comer needs 8" bumper side or the entire side <8" needs a bumper, your choice. Anything inside the frame perimeter shape does not need a bumper.

Your extension zone is now 15" beyond original frame perimeter with same shape.

[MrBasse]

Originally Posted by ICE_Bear

That was labeled "NOT OKAY" because the corner wasn't covered, not because it was less than an 8" piece of the side.

Since it's our chassis piece that's only 4.5 inches long, wouldn't each individual piece be a side?

Don't rely on pictures, READ the rules. If you just look at pictures you'll never get the whole story.

Earlier you referenced r19. Read r19. Then re-read r19 just to be sure. I'm on my 7th time through the full manual plus all the other times I have check little items in between. If you read it you'll get your answer and notice every side that is less than 8 inches must be fully covered. You'll also see that you need a minimum of 8 inches covered from each corner.

[mastachyra]

Word of this change needs to be spread more loudly, or many teams are going to have a major issue at competition. Our robot has been driving and picking up balls for two weeks and now we need to widen our chassis. This is a huge waste of time.

I'm currently looking at the rules we printed out on kickoff day, and this rule is unclear. I guess I interpreted the words "side" and "frame perimeter" to mean different things. The frame perimeter was clearly an imaginary line around the robot, but I took "side" to mean a physical side of the robot.

It was especially confusing because the rules say "If a side is shorter than 8 in., the entire side must be protected by BUMPER"

I can take a picture of the old figure 4-3: BUMPER Corner Examples if anyone is interested.

[Chris is me]

Originally Posted by mastachyra

Word of this change needs to be spread more loudly, or many teams are going to have a major issue at competition.

This isn't a change. This is how the rules have been written since the beginning - the only "change" is the addition of a picture to better explain the rule. The rules have been like this every year we've had openings in bumpers, going all the way back to at least 2009.