bumpers for interior perimeter
 

we were planning to have a cut out in the front of our frame to allow for our grasping mechanism ot be dropped to the ground. Will we need bumpers inside the cutout? now i dont thinks we do but i just want to make sure

Re: bumpers for interior perimeter
 

As stated in <R07> you will need bumpers to cover the entire bumper perimeter. Please look at how bumper perimeter is defined in section 1.6.

This being said, you can have a cut out if you would like, but the bumpers will still be in the way.

Re: bumpers for interior perimeter
 

No, you will not need BUMPERS inside the cutout. But you will need a BUMPER spanning the cutout, and the cutout cannot be more than 8 inches wide. See <R07> A and K, including Figure 4-3.

Re: bumpers for interior perimeter
 

"and the cutout cannot be more than 8 inches wide. See <R07> A and K, including Figure 4-3."

I believe that your interpretation is incorrect. <R07> and the corresponding pictures is describing the backing needed for the bumpers.

Re: bumpers for interior perimeter
 

Can you explain how I misinterpreted this?

Re: bumpers for interior perimeter
 

Here are the sound bites you should be thinking about that pertain to the discussion.

BUMPER PERIMETER – the polygon defined by the outer-most set of exterior vertices of the BUMPERS when they are attached to the HOSTBOT. (To identify the BUMPER PERIMETER, wrap a string around the BUMPERS at the level of the BUMPER ZONE - the string describes the polygon.)

If implemented as intended, a ROBOT that is pushed against a vertical wall in any STARTING CONFIGURATION will always have the BUMPER be the first thing to contact the wall

BUMPERS must provide complete protection of the entire FRAME PERIMETER of the ROBOT (i.e. BUMPERS must wrap entirely around the ROBOT). As part of the 100% coverage, BUMPERS must protect all exterior corners of the FRAME PERIMETER. For adequate protection,

BUMPERS segments must have a minimum length of six inches

BUMPER – an assembly designed to attach to the exterior of the HOSTBOT and constructed as specified in Section 3.4.2, Bumper Rules.

Re: bumpers for interior perimeter
 

Gary, Figure 4-3 clearly shows that a gap of 1/4" or less can go longer than 8" long, and a gap of less than 8" can go deeper than 1/4". Two separate parts are marked OK that are either longer than 8" or deeper than 1/4".

So either the rule is not written clearly or the pictures are wrong. Assuming the Figure 4-3 is right, the rule should really read something like, "Any gap that is deeper than 1/4" && wider than 8" will be considered unsupported." If the figure is wrong, all three marked areas are illegal.

Re: bumpers for interior perimeter
 

The cutout as described by the OP is an unsupported section of the BUMPER. Thus it is limited to 8".

I can see the disconnect between the written rule and the picture, and why my post might be misunderstood. I believe the GDC considers a bumper with 1/4" or less gap to be a supported bumper, not unsupported.

Re: bumpers for interior perimeter
 

So if i have a gap in between my drivetrain side plates that is about 4.75 inches across and 4 inches deep but still have an entire front bumper that goes all the way across, that is legal?

Re: bumpers for interior perimeter
 

According to figure 4-3, Yes. According to the text, ???

Re: bumpers for interior perimeter
 

Yep, unsupported needs to be that short--and spanned by bumpers is going to make life very interesting for those that were around in 2007.

dodar, the answer would be Yes, legal, assuming I'm reading the rule correctly. It's less than 8" across, even though it's more than 1/4" deep.

Re: bumpers for interior perimeter
 

so lets say i have a gap that is less than 8 inches long but more than 1/4 inch deep. there will be bumpers on each side of the cutout but i cannot put bumpers in front of the cutout beucase that is where the grasping mechanism must go to fit inside the dimensions of the starting robot is this illegal or not?

Re: bumpers for interior perimeter
 

Your frame perimeter is not 100% protected. Therefore, you are in violation of <R07-A> and will not be allowed to compete until there is 100% protection of the frame perimeter.

Re: bumpers for interior perimeter
 

I guess we'll just have to agree to disagree until Q&A starts up and answers this question. I believe that they can have the cut out. An open space would not make contact with a vertical wall LOL

I'd have to go back to the archives but I do not see the rule being much different than 2 years ago when when cut outs were permitted.

I believe that a few teams that plan on using forklift type mechanisms are planning on having a cutout so they can pick up parts from the floor. Only a guess. ::rtm::

Re: bumpers for interior perimeter
 

The rules changed significantly.
See the difference?

Re: bumpers for interior perimeter
 

Sunshine, it's not illegal because there's a cutout. It's illegal because a short distance of frame perimeter (which, I remind you, is independent of cutouts) has no bumpers on it, and the rule says (emphasis mine)

If it were something like 1/4", you might have a case, as normal bumper joints are nearly that big. But to be big enough to let an arm out, it's almost got to be several inches. Try being the LRI who lets it through because it's protected despite the gap, only to have every other team at the event complain that that team just got a competitive advantage!

Cutouts were permitted a couple years ago because there was not a 100% protection requirement. IIRC, it was something like 75-80%. Starting last year, it went to 100%.

Re: bumpers for interior perimeter
 

last year lots of teams had openings in their bumpers to allow for a kicker mechanism, pusher, etc while the cutout will be differnet the idea that the inside of the cutout would not be the first thing to touch a vertical wall in a collision it wouldnt need bumpers if you have anything that would help me make sure i am correct in this idea i would appreciate it

Re: bumpers for interior perimeter
 

Nobody in Michigan did, at least not among the 80% or more of teams that I saw. BUMPER coverage was required to be 100% last year too. The difference was that the BUMPER ZONE was higher last year, allowing the balls to go below the BUMPERS.

The issue is not the flat-wall test; the issue is the 100% BUMPER coverage requirement from <R07-A>.

Re: bumpers for interior perimeter
 

Last year, the bumpers were higher. There wasn't a single team to my knowledge that had a gap there intentionally (100% coverage again).

The frame perimeter is defined as The visual is to wrap a piece of string around the robot. They should have used a rubber band (and I told them so during the offseason). That string will show you the bumper perimeter. You need bumpers on 100% of that string. No bumpers over the cutout, no 100% coverage, fix it before you can play.

Re: bumpers for interior perimeter
 

Just last night I commented to another mentor - "You know, I haven't seen the rash of bumper questions, like in previous years. Maybe they are starting to get it!"

Maybe they just haven't done their chasis designs, yet! :)

Steve

Re: bumpers for interior perimeter
 

For our robot this year we wanted to have an inner angle so that when we go to deploy the minibot we could hit it with the inner angle and always be straight on to the pole is this allowed?
According to the rules "BUMPERS must provide complete protection of the entire FRAME PERIMETER of the ROBOT (i.e. BUMPERS must wrap entirely around the ROBOT). As part of the 100% coverage, BUMPERS must protect all exterior corners of the FRAME PERIMETER. For adequate protection, a full segment of BUMPER must be placed on each side of the corner"

but it also says "The
BUMPER location and design have been specified so that ROBOTS will make
BUMPER-to-BUMPER contact during most collisions. If implemented as intended, a ROBOT that is pushed against a vertical wall in any STARTING CONFIGURATION
will always have the BUMPER be the first thing to contact the wall."

so reading these over we should be able to do this but we wanted to be sure before we just started cutting and welding

Re: bumpers for interior perimeter
 

Interior angles and concave sections are not allowed in the FRAME PERIMETER - see that definition.

BUMPERS may span short segments that do not have a physical frame member along the FRAME PERIMETER - see <R07-K>.