pic: Is this corner considered protected?

[Scott Hill]

Thanks dtengineering for your comment.

BUMPERS, plural, are protecting both sides of the the corner because the similar BUMPER on the other side of the hitch is involved when that side hits the wall.

scott

edit: more specifically, the left side of the corner in question would be protected by BUMPERS (2) per above, and the right side of the corner in question is protected by the one BUMPER segment that completely covers it and the BUMPER segment to the right which is mitered into at the oblique angle.

[Mike8519]

The corner is defined as the singular point where the "string" that defines the bumper perimiter changes angle in someway. The corner shown only has one side protected by a BUMPER.

[joeweber]

There are many different views of this question. I thank all for there response. The one consistent thing that I have found is that even if it is legal to do it still may be turned down by the inspector. GDC will only refer you to the rules.

If we turn the corner/angle into a curve will it no longer becomes a problem.

Per GDC
3: A "C" configuration chassis for the ROBOT would be legal if, and only if, it satisfies all applicable Robot Rules.
4: A specific minimum radius threshold to determine the difference between corners and curves has not been, and will not be, defined. A "corner" will be determined to be a "corner" when upon inspection any reasonably astute observer perceives it to be a "corner" and not a curve.

[dtengineering]

I've been thinking of a better way to phrase this whole bumper rule thing so that it would serve the purpose and intent of the rule, be easy to test, unambiguous and yet simply and clearly stated.

I would suggest that the GDC could simplify this whole bumper thing by stating:

"When a robot, with trailer attached, approaches a wall, the first part of the robot or trailer to contact the wall shall be a bumper. This may be tested by pushing a 2x4 (representing a long wall) edgewise along the ground towards the robot. If the edge of the 2x4 touches any part of the robot, the robot is not protected."

But... there might be weaknesses in that rule that could lead to ambiguity when inspected by 1300+ teams. I don't envy the GDC their job and support/understand/appreciate their rulings 99.9% of the time. The other .1% of the time, I simply accept the ruling. Like I have a choice!

Jason

Jason

[Gdeaver]

What is the cost of squaring out the back end and ensuring this will pass inspection? Does the teams assumption that an angled rear gives some benefit to the trailer robot driving dynamics? The robot and trailer are to the point that the team should be able to test this assumption. I content that with the trailer dynamic our team has experienced, this angled rear design may not be desirable from a driving stand point. The team at this time will only loose a little build time this week modifying the design.
What is the cost if the team decides to stay with the current design and takes their chances that they can plead their case to the inspectors and prevail. If you loose this point at inspection, you will have a nasty day Thursday trying to Kluge up a fix in the pits. Our team has been there done that. I don't want to experience it again. Those who where there on our team now take a very Conservative view to the rules.

[Scott Hill]

Jason,

I really like your simple 2x4 test. It is unambiguous, easy to apply, and virtually the same as the vertical wall sentence from the lead paragraph of <R08>. I share your appreciation for the GDC and their efforts in a difficult task. The thing that makes this so critical is that there may well be many teams that show up at regionals (not to mention half way thru build season) with robots that may not comply with whatever the lead inspectors interpretation is and possibly face an insurmountable task to make their robot compliant.

Scott

[Al Skierkiewicz]

Scott,
In looking at the picture and visualizing certain field elements, I think it is entirely possible for an unprotected/non bumper portion of the robot to contact a field element or another robot. Certainly, the angle of the trailer tongue shown in the photo would allow a wide variety of possiblities, my robot included. In my mind, the rule that states in part...
R08 The BUMPER location and design have been specified so that ROBOTS will make BUMPER-to-BUMPER contact during any collisions. If implemented as intended, a ROBOT that is driven into a vertical wall in any normal PLAYING CONFIGURATION will always have the BUMPER be the first thing to contact the wall.
I would be hard pressed, from this photo, to be able to prove to myself that your robot design would be able to meet this specification.

[MamaSpoldi]

No one has addressed this part of these bumpers... the mitered corners of the plywood backing. This is not legal per rule <R08>.O (see also figure 8-4):

"The BUMPER backing must not extend beyond the “edge” of the ROBOT. The backing of adjacent BUMPER segments must not attach to each other if the attachment would require that the joint extend into the corner (see Figure 8 – 4)."

The pool noodles can wrap around the corner, but the plywood backing must stop at the edge of the frame. (You can see this is figure 8-2 as well, but you may have to zoom in a little to see it clearly.)

Note that in part N of this rule the statement that: " 'Hard' parts of the BUMPER (i.e. plywood backing, fastening system, and clamping angles) may extend up to a maximum of one inch beyond the BUMPER PERIMETER." is referring to the thickness of the backing (ie. the extension perpendicular to the bumper perimeter) rather than the length of the backing.

[This is also clarified in this Q&A posting: http://forums.usfirst.org/showthread.php?t=11279]

Also, regarding the corner protection, I would recommend also reviewing the answer given in this Q&A: http://forums.usfirst.org/showthread.php?t=11236. Our team had similar concerns about our bumper configuration. I agree that if there are doubts it is a good idea to opt for a less controversial implementation if it does not sacrifice any functionality.... or at a minimum have a retrofit already determined and ready to go to avoid too much pain if you are overruled.

[Gazelleman]

i agree

[johnr]

I would vote no on the bumper,but on a different note,wouldn't this extreme angle of trailer to bot allow an apposing bot to lock you up pretty good. I mean picture a bot driving into the lower left side of picture. Looks like it would be pretty hard to get away.

[Scott Hill]

Hi Al,
It's good to hear from you. For the record this isn't Winnovations robot but I think it raises certain points that are important to discuss.

With respect to your point regarding R08 BUMPER to BUMPER contact, the Manual allows up to 1/3 of the BUMPER PERIMETER to be unprotected by BUMPERS. Any ROBOT with a floor accumulator has to take advantage of this allowable 1/3 unprotected offering. Strict compliance with the BUMPER to BUMPER statement you reference would prohibit such accumulators. I don't think prohibition of floor accumulators is the intent of the GDC and I don't see how the portion of this ROBOT which is unprotected by BUMPERS is any more problematic than a floor accumulator opening/unprotected portion of the BUMPER PERIMETER.

Thanks, I look forward to seeing you, your team, and your ROBOT at Midwest

Scott

[Cory]

Originally Posted by Scott Hill

Hi Al,
It's good to hear from you. For the record this isn't Winnovations robot but I think it raises certain points that are important to discuss.

With respect to your point regarding R08 BUMPER to BUMPER contact, the Manual allows up to 1/3 of the BUMPER PERIMETER to be unprotected by BUMPERS. Any ROBOT with a floor accumulator has to take advantage of this allowable 1/3 unprotected offering. Strict compliance with the BUMPER to BUMPER statement you reference would prohibit such accumulators. I don't think prohibition of floor accumulators is the intent of the GDC and I don't see how the portion of this ROBOT which is unprotected by BUMPERS is any more problematic than a floor accumulator opening/unprotected portion of the BUMPER PERIMETER.

Thanks, I look forward to seeing you, your team, and your ROBOT at Midwest

Scott

Scott, I think if you read this Q&A response, it is pretty clear that you need a bumper segment on both sides of a corner, even though one bumper segment may adequately protect both sides of the corner.

[edit] This Q&A is the one I wanted-it makes it abundantly clear that both sides of the corner must have their own bumper segment.

[Paul Copioli]

Scott,

One important thing to consider is that many of us are picking up from the floor and the "6 inch minimum" + "all sides must have a bumper" GDC clarifications have constrained all of us. The ThunderChicken floor pick-up opening is not as large as we wanted specifically because of the bumper rule. Our robot base design was driven by the bumper rule. Our design is not as cool as we wanted it to be because of the bumper rule.

If any team has a design that looks like the picture at one of my competition, thenn I will bring it up to the inspectors because they will have a significant advantage over everyone esle and it is in violation of written clarifications by the GDC.

The huge advantage on the back of your robot is that you can get your trailer off to the side more to help protect it and you can swing around the trailer more to get a better angle at your opponent.

The advantages on the front side are obvious wrt opening size.

Maybe they left a loophole in on purpose, but if they did, then I say they are lawyering the rules and now we will have to do the same.

For the record, I hate bumpers and designing around the bumper rules, to me, is silly.

[Triple B]

Ya, what Paul said
mike d

[EricH]

Well, you got your official answer.

http://forums.usfirst.org/showthread.php?t=11600