pic: Week Three 2009

[Michael Corsetto]

This may be a premature assumption, but isn't it impossible (with the current configuration shown) to legally protect the back end with bumpers? There isn't 6 inches of space on either side of the trailer hitch to mount bumpers too, so both sides of those two rear corners can't be protected.

Besides nit-picking at this years bumper rules, looks like a pretty cool bot. Does it have two separate shooter "chutes" for balls to flow out of?

[dtengineering]

Oh my goodness... I was simply admiring the robot until the question about the bumpers came up.

My concern was initially over rule R8 part I, "Bumpers must protect all exterior corners of the bumper perimeter" as the corner between the trailer hitch section on the angled side piece is a corner and, with bumpers on only one side, would not be protected. However examining the reference figure 8-2, this design would be in keeping with the figure specifically referenced by the rule. I'm not up on all my bumper Q&A's, so perhaps there has been an answer to this already... but ARE the rear corners of the robot adjacent to the trailer hitch in figure 8-2 protected by bumpers? Do they have to be? If that hasn't been answered you might want to get an answer on that one as when a drawing is inconsistant with a wording, the wording takes precedence.

My other concern would be R18 E, concerning the trailer bumpers contacting the robot bumpers before the trailer tongue contacts the bumpers. It may be that this happens in this design, it is hard to tell without seeing it with bumpers on and a trailer attached.

I am assuming that with bumpers on the front of the robot that 2/3 of the bumper perimeter is covered?

Jason

[joeweber]

My concern was initially over rule R8 part I, "Bumpers must protect all exterior corners of the bumper perimeter" as the corner between the trailer hitch section on the angled side piece is a corner and, with bumpers on only one side, would not be protected.

Jason[/quote]


Would that not be an interior corner as apposed to an exterior corner? When the trailer is attached, that area becomes in inaccessible.

[Gdeaver]

To determine the bumper perimeter, ignore the trailer hitch and wrap a string around your robot. From the picture I see this forms 6 vertex's. Those are the corners and the rules say that the corners (vertex's) must be protected in both directions with bumpers that are a minimum of 6 ". The problem with this design is the 2 vertexes on either side of the trailer hitch. They only have bumpers on one side of the vertex ( corner). To modify your bumper area frame to be legal you might as well square it off and be done with it. From what I saw yesterday driving our robot, you probably will not gain any advantage with your frame trailer interactions. In fact your design can cause more problems trying to back up in a jack Knife situation.

[Vikesrock]

Originally Posted by Michael Corsetto

This may be a premature assumption, but isn't it impossible (with the current configuration shown) to legally protect the back end with bumpers? There isn't 6 inches of space on either side of the trailer hitch to mount bumpers too, so both sides of those two rear corners can't be protected.

The 2 corners on either side of the trailer hitch do appear to be exterior corners of the BUMPER PERIMETER which cannot be protected by BUMPERS on both sides of the corner with the pictured design.

[Alex Cormier]

There is no real need to go after these people if you look at the pictures on the teams site. It's all valid. So take some time and look at the pictures.

[Liz Smith]

Originally Posted by Alex Cormier

There is no real need to go after these people if you look at the pictures on the teams site. It's all valid. So take some time and look at the pictures.

I would take a pause before you declare that "it's all valid".

According to the rule book, <R08-I->, all exterior corners must be protected.

According to this Q&A (part 2):
"2. As indicated in Rule <R08-I>, all exterior corners of the BUMPER PERIMETER must be protected by BUMPERS. Both "sides" of the corner must be protected."
source: http://forums.usfirst.org/showthread.php?t=11159

According to this Q&A:

"An "exterior corner" of the ROBOT is one where the BUMPER PERIMETER forms a vertex...."
source: http://forums.usfirst.org/showthread.php?t=11270

From those, I have drawn conclusions about the robot frame designs I've been working with. I'm not the ultimate source of what designs are valid/not valid, but be aware that these Q&A responses are there and are very specific.

[=Martin=Taylor=]

Ah yes... the double barreled shotty...

A design very similar to ours. Looks awesome!

[Gdeaver]

To be so far along but with the bumper problems. You need to take corrective action next week.

[joeweber]

Pictures http://www.team1322.org/robotics_08-09.htm

Yes we will have bumpers on the angle corners. The trailer will make contact just before the trailer tong hits. We are hoping to be able to turn sharper with this design. That bumper segment is about 7 inches long. <R08> figure 8-2 shows an angle bumper. We are only human player feed. They say do one thing and do it well, we can load 20 balls and shoot them two at a time approximately 15 feet with camera assistance. We are balancing most of the weight on the two drive wheels, the rest of the weight (just enough to keep in on the ground on forward motion) will be forward on a single caster.

[MrForbes]

Originally Posted by joeweber

<R08> figure 8-2 shows an angle bumper.

After they published that drawing, they changed the wording of the rules to make it illegal to have your trailer hitch and bumpers that way.

You might want to ask on the Q&A forum if your specific design is legal. It would be much easier to fix over the next 3 weeks than on the Thursday of your first competition.

[dtengineering]

Originally Posted by Alex Cormier

There is no real need to go after these people if you look at the pictures on the teams site. It's all valid. So take some time and look at the pictures.

I don't think anyone is "going after" this team regarding their bumpers. In fact, I think everyone who has posted concerning the bumpers has expressed appreciation for the overall design, but have spotted a potential concern that we want to bring to the attention of the team.

There is clearly the potential for confusion between the wording of the rules, and figure 8-2 in the rules. The figure suggests that this design should be fine, but the wording of the rules seems to contradict the figure.

One advantage of posting photos, CAD images and sketches to CD is that it exposes your design to a number of FIRST veterans, including several experienced tech inspectors, who can offer suggestions if they see a potential rule violation. While the GDC will not rule on a specific design in the Q&A forum so asking "is this robot legal" is not a valid Q&A question, something along the lines of "The robot corners adjacent to the the trailer hitch in figure 8-2 of the game manual appear to be inconsistant with the requirement that all corners of the robot be protected by bumpers. Is special consideration meant to be given to such corners?" If it is possible to make the argument that in this design the rear corners are incapable of being the first part of the robot to contact another robot or playing surface then it may be that this bumper configuration is consistant with the intent of the rule (albeit not the current wording) and that the wording will be modified.

I hope the GDC rules favourably on this for the team. I can see how they could honestly believe their design to be legal. It is clearly consistant with figure 8-2 and is likely consistant with the intent of the bumper rules that the first part of a robot to contact a wall or other robot shall be the bumper.

Jason

[GaryVoshol]

Originally Posted by joeweber

Would that not be an interior corner as apposed to an exterior corner? When the trailer is attached, that area becomes in inaccessible.

Those corners are clearly a part of your BUMPER PERIMETER. Accessible or not, by letter of the rule they should be protected by 6" bumpers on each side.

Originally Posted by dtengineering

While the GDC will not rule on a specific design in the Q&A forum so asking "is this robot legal" is not a valid Q&A question, something along the lines of "The robot corners adjacent to the the trailer hitch in figure 8-2 of the game manual appear to be inconsistant with the requirement that all corners of the robot be protected by bumpers. Is special consideration meant to be given to such corners?" If it is possible to make the argument that in this design the rear corners are incapable of being the first part of the robot to contact another robot or playing surface then it may be that this bumper configuration is consistant with the intent of the rule (albeit not the current wording) and that the wording will be modified.

I hope the GDC rules favourably on this for the team. I can see how they could honestly believe their design to be legal. It is clearly consistant with figure 8-2 and is likely consistant with the intent of the bumper rules that the first part of a robot to contact a wall or other robot shall be the bumper.

I never noticed this apparent contradiction in Figure 8 -2. They are using that figure to illustrate allowable methods of extending the noodles to protect the corners. Yet the corners adjacent to the trailer hitch are not protected with 6" on both sides.

Joe, I would ask the question as Jason has worded it, and quickly. It's especially important as you are registered for a Week 1 District event. You can't risk an unfavorable ruling once you get there. (For those outside Michigan, if ruled against by an inspector, 1322 would not have a Thursday practice day to fix it; they would only have a few hours of Friday morning practice time.) See you in TC.

[EricH]

You guys are referencing fig. 8-2. I don't have a problem with that, except that I have 2.

1) The GDC has repeatedly said that the pictures in the rules are there merely for reference.

2) The figure has the right corners, but it also has bumpers on both sides of the corners, except right at the trailer hitch.

I think the question should read something like, "During the design process, we came up with a solution that we believe meets the intent of the bumper rules, but we would like to clarify that it meets the letter of the rules. [picture if necessary] We have an angled end such that every angle is an exterior corner and meets the bumper perimeter requirements. However, with the mounting of the trailer hitch, we can no longer put a 6" section of bumper between the hitch and the nearest exterior corner of the robot. We have confirmed that the trailer impacts bumper to bumper before the tongue hits. We think we won't need bumpers, but would like to confirm. If this design is not legal, we will change our design as necessary."

I would imagine that the GDC would either say, "we cannot comment on specific designs" or "This design does not meet <R08-X> and will not be legal."

[joeweber]

8.3 Robot Rules
When reading these Rules, please use technical common sense (engineering thinking) rather than “lawyering” the interpretation and splitting hairs over the precise wording in an attempt to find loopholes. Try to understand the reasoning behind a rule.

I thank everybody for the heads up on this issue. Although I have read the rules and intrepid them to the best of my ability I did miss the bumpers on the corners. I looked at the diagram and seen the angle near the hitch and thought we could do the same. There is no indication where an angle ends and a corner begins. It will be easy to install corners on our robot (or slight angles) and will probably will but in the mean time we will try different things. I have posted a photo of an idea and would like comments when it comes out.