Re: Robot frame/bumper question
 

Topgun,
So you are saying that you used the standard kitbot frame with the extrusions in the corners but your C channel did not extend to the corner? Then the inspector was correct in the decision. The desire of the GDC (as I understand it) is that bumper ends be backed by robot frame so that collisions do not damage the bumper or the mounting.
This was of more importance last year with teams trying to satisfy all of the bumper rules yet leave as large an opening for picking up balls as possible. An eight inch bumper segment on each side of the front of the robot only allowed a certain width of opening. Teams designed the robot for the larger opening and then made their bumpers only to find out that the bumper hung out over the opening.

Re: Robot frame/bumper question
 

It wouldn't be build season without at least one interesting bumper question!

But I still say this year's bumper rules are awesome.:)

Jason

Re: Robot frame/bumper question
 

I see that there's a lot of debate over this question now! One thing I noticed is that someone asked this question in the 2013 Q and A, located here: https://frc-qa.usfirst.org/Question/...o-have-bumpers
Of course, a more specific answer would've been lovely... but it is an official response. Thoughts?

Re: Robot frame/bumper question
 

Someone in Q&A is thinking like a politician - answering questions without saying anything. See post #6 for a frame perimeter drawing. #7 for more info.

Re: Robot frame/bumper question
 

http://frc-manual.usfirst.org/Updates/0#term 42

The updated drawing for R22 shows the appropriate way to put bumpers on an L-shaped robot.

Re: Robot frame/bumper question
 

Except for the corner that says "NOT OK".

Re: Robot frame/bumper question
 

Yes, I assumed that people would see the "not ok" label and realize that it was not ok.

Re: Robot frame/bumper question
 

I imagine what he meant was that there is no correct configuration for the type of corner listed as "Not OK". Is it required that a bumper extend downwards from "Not OK" corner to make it 'OK'? Or a bumper along the frame perimeter? The other side of the L has a slanted surface with bumpers, but that is a different corner layout completely.

So the drawing doesn't have a complete guide to what bumpers are needed on an 'L' shaped robot, as there isn't a completed 'OK' drawing.

Re: Robot frame/bumper question
 

That is because an 'L" shape robot will never be legal because of the bumper rule.

Re: Robot frame/bumper question
 

So everyone is on the same page, the thin black line on the drawing in Team Update 3 is the Frame Perimeter not the frame. The Frame Perimeter is determined by an imaginary string around the frame and inscribing the depicted polygon in each of the four drawings. The lower right drawing could be an "L" shaped robot or simply a design that has an opening in that part of the robot. The bumper shown (as added to the lower part of the opening) is a valid bumper on the Frame Perimeter, the "not OK" arrow is pointing at the missing but required bumper section on the Frame Perimeter that is needed to fulfill the "8" on either side of an exterior corner" bumper rule.

Re: Robot frame/bumper question
 

The bumper will also have to be supported by the frame 8" from each outside corner. The upper corner (not OK) has no structure to support the bumper. That is why an L shape robot cannot be legal. If you look closely at the "OK" lower corner of the L, It has structure to back up the frame. Once you do this, it is no longer a L

Re: Robot frame/bumper question
 

I agree that the structure needs to be added to support the bumper on the upper corner, but depending on how that is done, the robot could easily still resemble an L.

Re: Robot frame/bumper question
 

Our team just posted the three detailed drawings to Q&A that got virtually no response from the GDC. But after looking harder at the revised bumper rule figure, I think I finally understand.

If you have a polygon shaped robot (no idea how this works on a circular robot!) and you cut a notch out of your robot, and it only cuts out of one side, then if both remaining portions are at least 8 inches and covered in bumper, you are fine. No need to add and bumper material 'inside' the notch.

If you cut a notch that takes out one vertex (corner), then you have created two new 'virtual', shallower corners at the edges of the notch and a new perimeter line. Even though nothing sticks out, you still have to add bumpers to cover the other half of each new corner. And according to the third robot in the drawing, placing bumpers along inside edges does not count. So you have add 8 inches of perimeter frame to each side of where you cut out, or reshape the remaining portion to follow this new perimeter line.

Another, simpler way to look at it, you should be able to place a 60" board across any opening in the robot, and press flat against 8 inches of bumper at each edge. And you should be able to roll that board all the way around the robot and either press flat against 8 or more inches, an opening with 8 or more inches on both sides, or a fully padded corner.

The "L" shaped robot above with beveled tips should be legal. But the same robot with squared off ends and 8 inches of bumper on the inside of both 'arms' of the L would not.

Of course, this is my opinion from squinting harder at the Team Updates and reading between the lines of the non-responses from the GDC.

Mike

Re: Robot frame/bumper question
 

This.

As a long time inspector wannabe (someday I will be one), I think you have captured it pretty well. O think the hardest parts for many teams are the actual definition of the frame perimeter, and the meaning of the 8", but I think you have captured both reasonably well here. My only quibble is that the new vertices aren't virtual :-)

I hope you explanation un-confuses others.

When you get to round robots, it does get tricky.

Re: Robot frame/bumper question
 

I agree, but. It is 'virtual in the mind of a robot team that 'sees' a square robot with a bite taken out of one corner. It is real when an inspector looks at a section of robot perimeter with no robot frame to back it up. I was speaking to the robot designers, so I worded it for them :) !

I hope so too. Maybe the GDC will even add it in a little blue box in future team updates.

Not really. If you treat them like the GDC decided, and infinite number of vertices, then it must have the vertex "well filled", and pass the pressure onto to each side well, which basically means the full arc must be well padded. If there are any straight sections, then the regular rules apply there, end of arc flows into 8 inches of corner padding, possible gap if other side continues the same flat as this side, then 8 in minimum leading back into the arc. A 3/4 circle with a flat side that has two 8 inch flats with a corner cut out of the middle is easy to see meeting the rules this way, too.

Mike