Bumper Question

[Qbot2640]

I thought I knew the answer to this question, until I saw the following response on the Q&A today:

Q. Are the corners along the frame perimeter that are formed from an opening in one side of the frame (like the lower left-hand example in Figure 4-2) considered "outside corners" and, if so, require 8 in of bumper along the frame perimeter from those points?
2013-01-22 by FRC0069
A. Gaps in the ROBOT'S frame that do not create corners in the FRAME PERIMETER are not considered "outside corners" of the FRAME PERIMETER.

I can't think of a way of asking this question without getting the inevitable: "The purpose of this forum is to answer specific questions about specific Rules. We cannot comment absolutely on hypothetical situations..."

Can a robot have a cutout into one end (such as was common for the ball loaders last season) that would result in less than 8" of frame remaining on either side, if the additional 8" bumper requirement was added to the adjacent sides?

[MARS_James]

From the way the bumper questions are being answered, no you can't since you need 8 inches from all corners

[Al Skierkiewicz]

Q,
openings into the Frame Perimeter are allowed if all other rules are in compliance. If your robot Frame is 28" wide, an opening in that width can be as large as 12" wide while still meeting the 8" minimum rule. However, do not forget that bumpers can be anywhere in the 2" to 10" above the floor. That leaves several inches under the bumper without needing an opening in the frame.

[Qbot2640]

Originally Posted by Al Skierkiewicz

Q,
openings into the Frame Perimeter are allowed if all other rules are in compliance. If your robot Frame is 28" wide, an opening in that width can be as large as 12" wide while still meeting the 8" minimum rule. However, do not forget that bumpers can be anywhere in the 2" to 10" above the floor. That leaves several inches under the bumper without needing an opening in the frame.

This is exactly how I interpreted it, but then in update 2013-01-15 they addressed the possibility of a side that was less than 8", stating that the 8" requirement would then extend around the corner...again, I interpret this to refer only to a side <8" with two outside corners ...the response I quoted above made me question that - because it seems to me that it could be interpreted to indicate that the cut out section is, in a way, disregarded - and the 8 inch "side" requirement could continue after the cutout or around the corner.

I ask only because we had a pretty cool geometrical idea that we ruled out when we sketched it out and saw the implications of the bumper rule. Just wanted to make sure I did not miss a loophole.

[Al Skierkiewicz]

Under no circumstances can you have less than 8" of frame on either side of an exterior corner. An opening in the Frame Perimeter that does not create an exterior corner (use the string analogy for determining Frame Perimeter and exterior corners) does not require a bumper if the exterior corner minimum is satisfied. In my example, if a team designed a 15" opening in the side of the robot that is 28" long, there will not be 8" of frame on each side of the exterior corners.
The highlight is added to remind teams that the frame is where the 8" dimension is determined. This was a source of confusion in the past and the bumper rule this year and the accompanying drawings should make this point clear.

[DonRotolo]

Originally Posted by Al Skierkiewicz

Under no circumstances can you have less than 8" of frame on either side of an exterior corner.

I dunno Al, this posting seems to state quite explicitly that a frame perimeter element can be less than 8" - look under "general announcements". Corner A to corner B is shown as 6".

That being said, the bumpers still need to extend 8 inches from the corner, as shown in the image.

[Jon Stratis]

To make it more clear, maybe change it to:

Under no circumstances can you have less than 8" of frame along the frame perimeter on either side of an exterior corner.

[Al Skierkiewicz]

Don,
The illustration in Figure 2013-01-15 is showing an illegal bumper. From the text immediately above..."To satisfy the 8 in. requirement for Corner A, there must be at least 8 in. of BUMPER in each direction. "
I know this is confusing as many teams are measuring the Bumper segment but it is the Frame measurement that is the defining distance.

[Al Skierkiewicz]

Don,
The illustration in Figure 2013-01-15 is showing an illegal bumper. From the text immediately above..."To satisfy the 8 in. requirement for Corner A, there must be at least 8 in. of BUMPER in each direction. " I know this is confusing as many teams are measuring the Bumper segment but it is the Frame measurement that is the defining distance. However, the dimensions are only shown for the frame in the above Figure. One can think in terms of the bumper backing which is essentially the Frame.

[Cal578]

Al,
I believe Figure 2013-01-15 is showing a legal bumper. The text above the figure just describes how to measure.

To satisfy the 8 in. requirement for Corner A, there must be at least 8 in. of BUMPER in each direction. Thus, the measurement along the 6 in. side would continue past Corner B for 2 more inches.

(emphasis mine)

It looks like the GDC was describing how a frame perimeter can have a segment less than 8 inches and still be legal. For example, a circular frame and bumper could be legal.

Q137 seems to answer this issue.

Q. Does a robot with the convex hexagonal frame perimeter shown in R03 (Figure 4-1) satisfy R22 if one of the sides of that frame perimeter is less than 8 in. in length and that entire frame perimeter and all exterior corners are completely covered with bumpers?

A. Per the Blue Box in [R22], the 8 in. measurement is taken along the FRAME PERIMETER. For sides of the FRAME PERIMETER less than 8 in., this measurement wraps around the next outside corner(s) of the FRAME PERIMETER. Please see Team UPDATE 2013-01-15 for illustration.

(emphasis mine)

[GaryVoshol]

I thought the "Corner A" / "Corner B" figure in "General Announcements" on 1/15 was illustrating a method of making a short frame segment legal, not illegal. Since the A-B segment is only 6", there must be at least 2" of bumper beyond the end of the segment to be legal.

If the arrows bending around the corner indicate the combined length is 8", then it would be legal. The text says the measurement "would continue past" Corner B.

Since the good minds here can't agree, including the Chief Inspector, someone should ask Q&A if the 1/15 update was intended to show a legal configuration or an illegal one. I can see how it could be read either way.

[Tristan Lall]

I concur that it's supposed to be legal. The update is explaining how to measure the 8 in distance along the frame perimeter to satisfy the rules, rather than explaining that the bumper should be changed.

Originally Posted by Game Manual - Team UPDATE - 2013-01-15

To satisfy the 8 in. requirement for Corner A, there must be at least 8 in. of BUMPER in each direction. Thus, the measurement along the 6 in. side would continue past Corner B for 2 more inches.

The Q&A quoted above reinforces this interpretation.

Besides, it would be a very bad idea to overturn the more likely interpretation of the update two weeks later, in favour of a more restrictive one.

[FrankJ]

The rule interpretation about wrapping the 8 in measurement around a vertex allows you to have a side of the perimeter polygon less than 8". (Same as others are saying.) But in order to have a gap in the bumper, the side of the polygon will have to be >= to 8"+8"+gap length so you can have the 8" of bumper on both sides of the vertex.

[Al Skierkiewicz]

In asking for a clarification I was told that the illustration is to show that the entire frame is covered in bumper when the frame segments are less than 8". Much like an proposal, in another thread, I gave about a round robot with an infinite number of exterior corners needing to be completely covered with bumper.