Tips from a veteran Robot Inspector

[Cal578]

I don't see why people interpret [R28] to be so restrictive. [R28-B] has the phrase "(e.g. plywood, fasteners, etc)", which clearly opens up other parts. [R28-E] likewise has "All removable fasteners (e.g. bolts, locking pins, pip-pins, etc.) will be considered part of the Bumpers." And [R28-F] mentions "structures", without any definition of a structure or what materials may or may not be used in a structure. When I see "e.g." (==for example) and "etc." (==and so forth), I definitely think the list is not exclusive.

For the record, our bumpers are just made of the standard items. I question this interpretation because I've seen other people post questions about other materials, get told it's illegal, yet I don't see the justification, and I've never actually seen a team have trouble at an official inspection.

[loyal]

If the plywood on a bumper measures 7-7/8" lets say, then when you add on the fabric and noodles, if the bumper now measures 8" would an inspector accept this as a legal bumper? Or think about discrepancies in measuring devices like a tape measure as apposed to a machinist rule. Just asking how exacting will a inspector be? I realize that 7-3/4" is totally to short but where would an inspector draw the line? an 1/8", a 1/16", a 1/32"? zero tolerance? Just asking

[rsisk]

Originally Posted by loyal

If the plywood on a bumper measures 7-7/8" lets say, then when you add on the fabric and noodles, if the bumper now measures 8" would an inspector accept this as a legal bumper? Or think about discrepancies in measuring devices like a tape measure as apposed to a machinist rule. Just asking how exacting will a inspector be? I realize that 7-3/4" is totally to short but where would an inspector draw the line? an 1/8", a 1/16", a 1/32"? zero tolerance? Just asking

The inspector should be measuring the frame backing the bumper you are describing to determine if it is 8", then measure the plywood to make sure it is 8" as required by R27. I'll be using an ordinary measuring tape and if it is at 8" according to my tape measure, then I would pass the bumper. I wouldn't consider 7-3/4" to be 8".

[remulasce]

I don't see why people interpret [R28] to be so restrictive. [R28-B] has the phrase "(e.g. plywood, fasteners, etc)", which clearly opens up other parts. [R28-E] likewise has "All removable fasteners (e.g. bolts, locking pins, pip-pins, etc.) will be considered part of the Bumpers." And [R28-F] mentions "structures", without any definition of a structure or what materials may or may not be used in a structure. When I see "e.g." (==for example) and "etc." (==and so forth), I definitely think the list is not exclusive.

[R28-B]

hard Bumper parts (e.g. plywood, fasteners, etc) may not extend more than 1 in. beyond the end of the Frame Perimeter(see Figure 4‑4).

The (stuffinparens) do open up other parts- as an adjective to the collection, "Hard Bumper Parts". Then a restriction is placed upon these "Hard Bumper Parts", which thus restricts all those other parts now included in "Hard Bumper Parts". It does not legalize all hard bumper parts.

If a rule specifically enumerated that all lasers in the bumper must be within 1" of the frame, it would still not legalize lasers.

You may be confused why time was taken to enumerate through these specific parts. For this, see [R28E], which specifically requires you to build something on your own. It's because of this stuff that broader restrictions are necessary.

Basically, everything in the bumper must be exactly as proscribed, except for that one part in which you must design your own mounting system. This could include hard parts (plywood, fasteners, etc), so there had to rule limiting hard parts. But because the rule proscribes a mounting system, it has to be just a mounting system, even if it seems strong enough to be part of the frame.

[martin417]

Originally Posted by Al Skierkiewicz

Now that week 1 is under the bridge (pun intended) let us take a look at some additional items.

This weekend it seems that bumpers continue to be an issue. Regardless of previous year's rules, the minimum bumper segment must be 8" long and be supported by robot frame. The ends may not extend past robot frame and be unsupported. In other words, if you have constructed your robot frame to be 6" wide on either side of a ball handler opening in your frame, this is an illegal design. The frame and bumper must be a minimum of 8" and the bumper must be fully supported by the frame (except with certain exceptions listed in R33) You cannot have a 6" frame segment with an 8" bumper segment mounted to it allowing the bumper to extend beyond the frame.

Numbers on the bumpers must be in four places and four only. The team numbers must not be segmented or split across an opening or across two bumper segments. The GDC has ruled on this and is very clear in how teams are to implement the rule and how inspectors are to judge the bumper design.

While inspectors will not rule on appendage usage, we will inspect for the distance outside the frame that any appendage can travel during a match. If you appendage is capable of extending beyond 14 inches and has some limit in place (either mechanical stops or software) then they will check that during inspection as well.

Rev C of the Inspection Checklist was issued on Tuesday. This will be the version used at events except if an updated checklist is issued.

I would like to remind everyone that modification of motors is only allowed for very specific reasons...
R49
Motors, servos, and electric solenoids used on the Robot shall not be modified in any way, except as follows:
A. The mounting brackets and/or output shaft/interface may be modified to facilitate the physical connection of the motor to the Robot and actuated part.
B. The electrical input leads may be trimmed to length as necessary.
C. The locking pins on the window motors (PN 262100-3030 and 262100-3040) may be removed.
D. The connector housings on the window motors (PN 262100-3030 and262100-3040) may be modified to facilitate lead connections.

Please note that this does not allow modifications to motors or integral transmissions even if the manufacturer supplies a mod kit. It does not allow the removal of integral transmissions to use the motor only.

I hope all teams participating in Week Two events have a great time.

I originally interpreted the rule this way too, but then this Q&A came out:

Q. The Bumper must be 8 inches - Is the length of the Bumper (8 inches) defined by the length of the plywood, noodle, or the robot perimeter? FRC1124 2012-02-19
A. The full length of the Bumper must include all Bumper components required per Rule (R28).

Rule (R28) says:

[R28]
Bumpers must be constructed as follows (see Figure 4‑4):
A. be backed by ¾ in. (nominal) thick by 5 in. tall plywood.

B. hard Bumper parts (e.g. plywood, fasteners, etc) may not extend more than 1 in. beyond the end of the Frame Perimeter(see Figure 4‑4).


C. use a stacked pair of 2-½ in. “pool noodles” as the bumper cushion material which completely covers the plywood. Cushion material may extend up to 2-½ in. beyond the end of the plywood.

D.be covered with a rugged, smooth cloth. The cloth must completely enclose all exposed surfaces of the plywood and pool noodle material. The fabric covering the Bumpers must be a solid red or blue in color. Visually, the red or blue must be as close to the corresponding color in the FIRST logo as reasonable (i.e. to a reasonably astute observer, they appear similar). The only markings permitted on the Bumper fabric cover are the team number (see Rule [R35]).

E. must attach to the Frame Perimeter of the Robot with a rigid fastening system to form a tight, robust connection to the main structure/frame (e.g. not attached with Velcro). The attachment system must be designed to withstand vigorous game play. All removable fasteners (e.g. bolts, locking pins, pip-pins, etc.) will be considered part of the Bumpers.

F. Each set of Bumpers (including any fasteners and/or structures that attach them to the Robot) must weigh no more than 20 lbs.

(Emphasis mine)

So that 2-12 inch extension is part of rule (R28), therefore is part of the 8" required. So the way I read the rule and the Q&A answer, a 6" long plywood back with 2-1/2 inch cushion extension would within the rules.

[Jaxom]

Originally Posted by loyal

If the plywood on a bumper measures 7-7/8" lets say, then when you add on the fabric and noodles, if the bumper now measures 8" would an inspector accept this as a legal bumper? Or think about discrepancies in measuring devices like a tape measure as apposed to a machinist rule. Just asking how exacting will a inspector be? I realize that 7-3/4" is totally to short but where would an inspector draw the line? an 1/8", a 1/16", a 1/32"? zero tolerance? Just asking

If both the frame behind the bumper segment and the plywood part of the bumper are 8" or more, they pass. If they're shorter than 8" I tell them to fix the problem, but if they're within 1/4" or so and haven't figured out that they can ask for the LRI to take a look I'd remind them. If they're a rookie team AND if it's going to be really hard to add the distance I'd be inclined to give them a bit of a break, and would recommend that to the LRI.

And I'm quite happy with the accuracy of my Stanley tape measure, thanks.

[martin417]

Originally Posted by Jaxom

If both the frame behind the bumper segment and the plywood part of the bumper are 8" or more, they pass. If they're shorter than 8" I tell them to fix the problem, but if they're within 1/4" or so and haven't figured out that they can ask for the LRI to take a look I'd remind them. If they're a rookie team AND if it's going to be really hard to add the distance I'd be inclined to give them a bit of a break, and would recommend that to the LRI.

And I'm quite happy with the accuracy of my Stanley tape measure, thanks.

Again, what problem? (ref my post above). The Q&A answer seems quite clear, if the bumper parts are described by (R28) they are part of the 8" requirement. The 2-1/2" noodle extension is described by (R28-C), so is therefore part of the 8". Nowhere does any rule state the the plywood backing must be 8" long.

[Jon Stratis]

Originally Posted by martin417

Again, what problem? (ref my post above). The Q&A answer seems quite clear, if the bumper parts are described by (R28) they are part of the 8" requirement. The 2-1/2" noodle extension is described by (R28-C), so is therefore part of the 8". Nowhere does any rule state the the plywood backing must be 8" long.

This is the problem:

[R27]

Robots are required to use Bumpers to protect all exterior vertices of the Frame Perimeter. For adequate protection, at least 8 in. of Bumper must be placed on each side of each exterior vertex (see Figure 4‑1, Figure 4‑2, and Figure 4‑3).

You can't count the material in the corner - you need 8" on each side of the exterior vertex of the frame perimeter. That means you need 8" of frame with 8" of plywood and 8" of pool noodles and 8" of durable cloth covering in front of it. That is the absolute minimum length a bumper section can be when attached to the corner of the robot. It can be longer - you can have another 1" of plywood hanging off the end of the frame perimeter (R28B), you can have "soft parts" of the bumper extend another 2.5" past the frame perimeter (R28C), and you can extend the bumper further down the frame perimeter away from the vertex (you can even have the entire length of the frame perimeter covered in bumper if you want!).

People keep trying to lawyer this rule, and have been for a long time now... it's written clearly, and your LRI will tell you to fix it if you have 5.5" of bumper with 2.5" in the corner - argue all you want that it meets the requirements for R27, you won't get your sticker until you fix it.

[45Auto]

Read R27 and R33.

You must have at least 8" of bumper on each side of the exterior frame vertices.

Bumpers must be supported by the structure of the robot, and rigidly attached at each end.

Do you really think you can rigidly attach 2 1/2" of pool noodle to the structure of your robot?

[martin417]

Originally Posted by Jon Stratis

This is the problem:


You can't count the material in the corner - you need 8" on each side of the exterior vertex of the frame perimeter. That means you need 8" of frame with 8" of plywood and 8" of pool noodles and 8" of durable cloth covering in front of it. That is the absolute minimum length a bumper section can be when attached to the corner of the robot. It can be longer - you can have another 1" of plywood hanging off the end of the frame perimeter (R28B), you can have "soft parts" of the bumper extend another 2.5" past the frame perimeter (R28C), and you can extend the bumper further down the frame perimeter away from the vertex (you can even have the entire length of the frame perimeter covered in bumper if you want!).

People keep trying to lawyer this rule, and have been for a long time now... it's written clearly, and your LRI will tell you to fix it if you have 5.5" of bumper with 2.5" in the corner - argue all you want that it meets the requirements for R27, you won't get your sticker until you fix it.

OK, I understand. As I said, I originally interpreted the rule as requiring the hard parts to be 8", but after reading the Q&A and (R28) I re-thought my interpretation. I now see that I should have also re-read (R27). That makes it all clear.

(By the way, our bumpers do comply, I was just trying to understand the intent, not "lawyer" the rules". I hate that term by the way, everyone need to understand the rules in all their nuance, because the GDC rarely answers a question in a way that removes doubt or adds much to clarity.

[Al Skierkiewicz]

Martin,
You have pointed out a common mistake when checking the rules. In the case of the Q&A the answer is referring to the bumper. Another part of the rules say that the bumper must be fully supported by robot frame.

[R33]
Bumpers must be supported by the structure/frame of the Robot (i.e. each end of the Bumper must be rigidly attached
to the Frame Perimeter, the gap between the backing material and the frame must not be greater than ¼ in. and no
section of Bumper greater than 8 in. may be unsupported). See Figure 4-7.

It is for this reason, I always add..."all bumper rules must be satisfied".

[Joe Ross]

Originally Posted by GaryVoshol

The most common method of "erasing" the 5th bumper number is to put tape over it. So they exchange one rules violation for another. Is that what we really want?

Allowable bumper materials are plywood, noodles, fabric, fasteners and optional angle reinforcements. Nothing else.

Do you also believe that paint, sharpie ink, and embroidery thread are illegal since they aren't on that list?

[Alan Anderson]

Originally Posted by Joe Ross

Do you also believe that paint, sharpie ink, and embroidery thread are illegal since they aren't on that list?

<R35> says team numbers must be displayed on the Bumper. It doesn't quite say the markings are considered part of the Bumper, though that much word-warping is probably silly. I'll just say that I believe the markings are not part of the Bumper construction.

[martin417]

Originally Posted by Al Skierkiewicz

Martin,
You have pointed out a common mistake when checking the rules. In the case of the Q&A the answer is referring to the bumper. Another part of the rules say that the bumper must be fully supported by robot frame.

[R33]
Bumpers must be supported by the structure/frame of the Robot (i.e. each end of the Bumper must be rigidly attached
to the Frame Perimeter, the gap between the backing material and the frame must not be greater than ¼ in. and no
section of Bumper greater than 8 in. may be unsupported). See Figure 4-7.

It is for this reason, I always add..."all bumper rules must be satisfied".

Which brings up one of my gripes about the way the GDC answers Q&A. The question was asked clearly. They could have answered the question in a way that actually answered the question and removed all ambiguity. Instead, they answered the question in a way that caused at least one person (me) to re-interpret the rules incorrectly. I understand that they don't want to analyze designs in the Q&A, but they answered the very same question very clearly in the team update from yesterday. Why not do that during the build season?

[Al Skierkiewicz]

Martin,
You are not the only one who has complained about the answers. Although this may be of little comfort, please remember that for every question answered the GDC spends a great deal of time discussing the ramifications. It is not a perfect system but it is the only one we have right now. I will pass your message along when I can.