Fasteners extending outside the FRAME PERIMETER

[Chris Fultz]

If the protrusions are excluded from the determination of the perimeter, then how can they then be in violation of the perimeter.

This one seems straightforward.

[mikelowry]

Originally Posted by Chris Fultz

If the protrusions are excluded from the determination of the perimeter, then how can they then be in violation of the perimeter.

This one seems straightforward.

They are excluded from determination. Meaning the FRAME PERIMETER is only determined by frame members. Thus, any bolts protruding from the frame members would also be protruding from the FRAME PERIMETER and would be illegal according to rule <R16>

[EricH]

Chris (and others who are asking/explaining), a picture is worth a thousand words. The attached picture is representative of one side of a typical robot. The red line is the frame perimeter's vertical projection. Under <R16>, anything to the right of it (bumper side) is a rules violation, except the bumpers.

What two items do you see extending out to the right of the line? Yep, two bolts.

Before Update #6, the upper bolt defined the perimeter, saving the lower bolt from going beyond the perimeter. After Update #6 (and before Update #7), the upper bolt no longer defines said perimeter.

[Chris Fultz]

Originally Posted by Chris Fultz

If the protrusions are excluded from the determination of the perimeter, then how can they then be in violation of the perimeter.

This one seems straightforward.

My first sentence was a statement, not a question.

The update says that the protrusions are excluded in determining the perimeter. Therefore, they cannot be considered in voilation of the frame perimeter if they are not considered when defining it.

It is sort of like the weight rule and batteries. Your weight limit excludes the battery. If you pass weight without the battery, then you cannot be considered overweight when you put the battery in.

[engunneer]

That is exactly the unanswered question, Chris.

The protrusions at the level of the bumpers are indeed excluded for determining the frame perimeter. There is no argument here, since the team update #6 makes it clear.

However, <G30> explicitly lists all things which are allowed outside the frame perimeter. <G30-a> in particular limits all things from being outside the frame perimeter below the bumper zone, except for the 2 second exclusion, and that is only allowed for ball interaction.

The big difference between this year and previous years is that the bolts for wheels and things used to also be in the bumper zone, and are part of the protrusion exclusion. Since the bumper zone is so much higher this year, this is no longer the case, and they need to be treated as any other part of the robot and kept within the frame perimeter.

If the GDC were to update <G30> to expand the protrusions allowed to the entire height of the robot, then the different drawings in this thread would become legal. Until, then I still say it's safest to assume they are not, and plan accordingly.

Inspections this year may be particularly tricky!

[Tristan Lall]

Originally Posted by Chris Fultz

My first sentence was a statement, not a question.

The update says that the protrusions are excluded in determining the perimeter. Therefore, they cannot be considered in voilation of the frame perimeter if they are not considered when defining it.

It is sort of like the weight rule and batteries. Your weight limit excludes the battery. If you pass weight without the battery, then you cannot be considered overweight when you put the battery in.

Unfortunately, you can't think of it that way.

The frame perimeter is (by both the original and the amended definitions) determined based on things within the bumper zone—when determining the frame perimeter, you're therefore only considering fasteners within the bumper zone. Nothing outside of that zone is relevant to "the determination of the FRAME PERIMETER".

Checking for compliance with <R16> and <G30> is a process that is not changed in any way by the update. You take the defined frame perimeter (which excludes minor protrusions in the bumper zone), and you find the extent to which the rest of the robot protrudes around it.

The key is that Update #6 only deals with the definition of frame perimeter. All of the rules that rely on that definition are unaffected.


On the subject of intent, I don't think it's so self-evident that the GDC intended to allow minor, non-frame-perimeter protrusions. After all, the rationale from the update was "to permit a simplified definition of the FRAME PERIMETER"—mission accomplished—"and encourage a tight, robust connection between the BUMPERS and the FRAME PERIMETER"—which has nothing at all to do with fasteners outside the bumper zone.

I don't disagree that letting minor protrusions (anywhere on the robot) exceed the frame perimeter would have merit. But based on the text of the update, I don't see a compelling reason to assume that we should be expecting the rule to change, or that the GDC miscommunicated their intent.

In any case, this won't be a huge deal to solve (if the rules remain as-is). Since it's (hopefully) well-understood that none of this applies to the maximum robot size, presumably any team using non-frame-perimeter protrusions on their robot will also have space to include a series of shim plates behind their bumpers to extend the frame perimeter outward.

[martin417]

Originally Posted by Chris Fultz

My first sentence was a statement, not a question.

The update says that the protrusions are excluded in determining the perimeter. Therefore, they cannot be considered in voilation of the frame perimeter if they are not considered when defining it.

It is sort of like the weight rule and batteries. Your weight limit excludes the battery. If you pass weight without the battery, then you cannot be considered overweight when you put the battery in.

No, it's nothing like the battery rule. <R10> A states:

A. Exception: solely for the purposes of determining compliance with the weight and volume limitations, these items are NOT considered part of the ROBOT and are NOT included in the weight and volume assessment:

This is crystal clear. No argument. The wording in question is not a rule, it is a DEFINITION. That wording DEFINES the frame perimeter. It make no rule about what may or may not extend past that perimeter. That definition is clear. By that definition, the frame members alone define the FRAME PERIMETER, the fasteners are excluded. The RULE this wording affects is <R16> and is equally clear:

During normal operation no part of the ROBOT shall extend outside the vertical projection of the FRAME PERIMETER, except as permitted by Rule <G30>.

I don't see any argument. From a lawyer point of view, (and the inspector is, and must be, a lawyer about the rules) The RULE refers to the DEFINITION. Both the RULE and the DEFINITION are clear. Regardless of intent, or how the GDC meant it, it is currently illegal for fasteners to extend outside the frame members.

Again, I am not trying to cause problems, but to prevent them. Inspectors and teams should abide by the wording of the rule, teams can't be expected to guess the intent of the framers and try to abide by that intent.

[martin417]

I have asked our team contact to post the following question on the Q&A. Let's hope for a speedy answer to clear this up. Just for informational purposes, our team has decided to re-design the robot to eliminate any fastener protrusions, we can't wait any more.

With the new wording for the definition of FRAME PERIMETER, any fasteners that protrude from the frame members, regardless of where they are located, are now excluded from the determination of the FRAME PERIMETER, so the FRAME PERIMETER is now determined only by the frame members. This is a more restrictive definition of the FRAME PERIMETER.

<R16> states: During normal operation no part of the ROBOT shall extend outside the vertical projection of the FRAME PERIMETER, except as permitted by Rule <G30>.

<G30> does not make allowances for fasteners. So by <R16> and the definition of FRAME PERIMETER, no fasteners may protrude from the frame members. However, <R07>D appears to allow clearance pockets, presumably for fasteners protruding from the frame members.

After much discussion, it is our opinion that the intent of the GDC is to allow fasteners to protrude from the frame members, therefore beyond the frame perimeter. The current wording of the rule and the definition of the FRAME PERIMETER prohibit such protrusions.

Can we get a clearly worded (yes or no) answer to this question:

Are fasteners allowed to extend beyond the frame members (as long as they are inside the max dimensions)?

If the answer is yes, can we get a rule or definition change so that there will be no questions at inspection?

[EricH]

The GDC has responded in Update #7. However: the exclusion from <R16> for fasteners in the bumper zone apparently does not apply to fasteners above or below it. Status quo again...

The next question to ask is: Given the exemption for fasteners in the bumper zone, what about fasteners and similar items above and/or below the bumper zone? Is the exemption intended to also apply to them, or is it only in the bumper zone?

[mikelowry]

Just asked the next logical question on the Q&A:

We understand that according to team update 7, minor protrusions such as fastener ends, bolt heads, etc. within the bumper zone, are permitted. Will there also be an exception made for similar minor bolt head protrusions that are below the bumper zone? Such as for drivetrains and such?

[martin417]

I'm not sure it's necessary to ask. It looks clear this time. I would bet that they were careful in their wording to say exactly what they wanted to say, and to express their intent. In that, I am glad that we re-designed the robot to eliminate the axle bolts beyond the frame perimeter, they were definitely below the bumper zone. Sadly, I expect this to be a major problem for teams that don't pay careful attention to rules and updates. I would expect to see many teams failed at inspection for this rule, and long lines at inspection as they are re-inspected. I hope they can get legal in time to compete.

[Vikesrock]

Originally Posted by martin417

Sadly, I expect this to be a major problem for teams that don't pay careful attention to rules and updates. I would expect to see many teams failed at inspection for this rule, and long lines at inspection as they are re-inspected. I hope they can get legal in time to compete.

I completely agree. I totally missed this when we did our initial frame design.

For rules compliance we will likely be going with some 1/4" plywood to widen out our upper frame.

Another cleaner looking option would be to make threaded axle support blocks that rest in the C-channel and eliminate the need for a bolt head or nut to sit outside the frame

[Joe Johnson]

Originally Posted by Vikesrock

I completely agree. I totally missed this when we did our initial frame design.

For rules compliance we will likely be going with some 1/4" plywood to widen out our upper frame.

Another cleaner looking option would be to make threaded axle support blocks that rest in the C-channel and eliminate the need for a bolt head or nut to sit outside the frame

But at least teams have time to fix it.

I honestly have no dog in this hunt as the robot our team is building meets the rule without even the fastener head exemption in the bumber zone* but I am really glad that this was addressed soon and clearly.

Well done GDC.

Joe J.


*this being the first year back in the game in a while and therefor not poluted with prior year's rulings, I read the rules and thought they were pretty clear. So... I used C channel facing outward for both the bumper mount structure and the robot chassis. As noted above, it leaves plenty of room for screw heads. Recommended.

[Vikesrock]

Originally Posted by Joe Johnson

But at least teams have time to fix it.

....

Well done GDC.

Joe J.

This is true, assuming they know they have a problem.

I am in no way blaming the GDC for me being dumb when working on our frame. The rules as written were crystal clear and we plain and simple messed up.

Luckily the dirty fix requires very little work and the clean one may be well within our capabilities as well (the question becomes is it worth the time)

EDIT: Paul's post made me think about this a bit more and I now agree with him that Update 6/7 could be extremely obnoxious for teams. A vertical member with a fastener at the bottom (below the bumper zone) and at the top (in the bumper zone) was previously perfectly fine and is now illegal.

To be fair there certainly was a rules oddity here that needed addressing. The rules allowed for the bumpers to be pocketed to allow room for fasteners, but the bumpers had to be mounted to the frame perimeter which was defined by these fasteners.

I still feel the appropriate way out of this hole is allowing for minor protrusions as defined in Update 6/7 to stick out from the vertical projection of the Frame Perimeter (whether above, below, or in the bumper zone) provided everything stays within the 28"x38" box.

[Paul Copioli]

No, no, no. This is not good job GDC! Bad GDC, bad GDC. We are in week 4 of the build season for Pete's sake. This makes no sense to me at all. On the scale of things that matter to them, this should be in negative land.

Good job GDC. I didn't need the sleep anyway.