View Full Version : How is 54" size limit being inspected?
Bob Steele
13-03-2013, 23:52
We aren't competing until the 4th week ( and the 5th and the 6th)
Can anyone enlighten me as to how a team needs to confirm that they meet the 54" rule?
Are inspectors asking this question? Are they asking a team to expand to its full size and measuring..??
just wondering.
We have a CAD drawing that shows our extensions to give an inspector to show how we meet the rule.
thanks!
We aren't competing until the 4th week ( and the 5th and the 6th)
Can anyone enlighten me as to how a team needs to confirm that they meet the 54" rule?
Are inspectors asking this question? Are they asking a team to expand to its full size and measuring..??
just wondering.
We have a CAD drawing that shows our extensions to give an inspector to show how we meet the rule.
thanks!
We printed off a few cad models to prove that we didn't exceed 54". The inspector said he appreciated this. To manually check, he took a measuring tape, and measured from furthest point to furthest point.
At Northern Lights we had to declare our maximum extensions so that they could make the refs aware. It might have been measured because the person with the exact answer was not there but the way the conversation was going it might not have been measured if the answer was confident (the parts were extended, though). I am guessing if the number given did not sound realistic a measuring would have happened anyway.
Darren Collins
14-03-2013, 00:02
In Portland, the inspectors had a 54" circle taped on the floor. The robot was placed in the circle. Any mechanisms or appendages were extended to ensure that the 54" cylinder wasn't breached. They also used a square made of wood and placed it at the edge of the circle to see if anything above the floor broke the cylindrical barrier.
I ask teams to extend any components that go outside the frame perimeter then pull out a measuring tape.
I ask teams to extend any components that go outside the frame perimeter then pull out a measuring tape.
Same thing happened at our inspection, but that doesn't measure a true 54" diameter in most cases.
Grim Tuesday
14-03-2013, 00:10
We printed off a few cad models to prove that we didn't exceed 54". The inspector said he appreciated this. To manually check, he took a measuring tape, and measured from furthest point to furthest point.
This is not the correct way to check. Our robot (see signature) is very close to being over the 54" limit, I think we were within about 1/2 an inch. The maximum point method will pass illegal robots. See the below picture for an explanation:
http://i.imgur.com/pDNlj09.jpg
At Fingerlakes, after an Inspector tried this method, we informed him why it was wrong and they pulled out a prinout of a 54" circle, which they projected upwards with an ruler. This seems like the correct method to use.
This is not the correct way to check. Our robot (see signature) is very close to being over the 54" limit, I think we were within about 1/2 an inch. The maximum point method will pass illegal robots. See the below picture for an explanation:
http://i.imgur.com/pDNlj09.jpg
At Fingerlakes, after an Inspector tried this method, we informed him why it was wrong and they pulled out a prinout of a 54" circle, which they projected upwards with an ruler. This seems like the correct method to use.
Agreed, that makes much more sense. We never got pulled to the printout at Finger Lakes though. I was surprised that this wasn't standardized between different regional, but how can the cylinder not be measured the same way within a regional?
s_forbes
14-03-2013, 00:30
This is not the correct way to check. Our robot (see signature) is very close to being over the 54" limit, I think we were within about 1/2 an inch. The maximum point method will pass illegal robots. See the below picture for an explanation:
http://i.imgur.com/pDNlj09.jpg
At Fingerlakes, after an Inspector tried this method, we informed him why it was wrong and they pulled out a prinout of a 54" circle, which they projected upwards with an ruler. This seems like the correct method to use.
The point to point method will still work if the inspector measures from the bumper corner to the mechanism corner (at least for most cases), but I could see this being missed. EDIT: doh, math. No it wont.
I was looking forward to seeing a cylindrical sizing box this year, but given the quality of sizing boxes in the past, I probably would have hated it. :rolleyes:
Radical Pi
14-03-2013, 00:37
Agreed, that makes much more sense. We never got pulled to the printout at Finger Lakes though. I was surprised that this wasn't standardized between different regional, but how can the cylinder not be measured the same way within a regional?
As I understand it, the measuring tape was supposed to be used to get a rough idea of whether they were at risk of breaking the cylinder. They subtracted a portion from the 54" to account for the circular nature of the cylinder and measured that. If you were close, you'd get pulled to the real circle for a closer inspection.
As I understand it, the measuring tape was supposed to be used to get a rough idea of whether they were at risk of breaking the cylinder. They subtracted a portion from the 54" to account for the circular nature of the cylinder and measured that. If you were close, you'd get pulled to the real circle for a closer inspection.
We were right on the verge as shown in our CAD, we were within 1/2" of 54". We clearly told the inspector this, which is why I'm confused.
Are inspectors asking this question? Are they asking a team to expand to its full size and measuring..??
We're certainly supposed to be asking this; it's a specific item in the inspection checklist. If this doesn't come up during your inspection ask the inspector why not.
At Hub City, afaik we only had one robot that had any possibility of an issue with this. I happened to be the inspector; by mutual request (team and the inspectors) we went through a reasonably exhaustive series of measurements to determine that there was no problem. We didn't have any kind of circle drawn to do this, but a tape measure and a little math did the trick.
Ask me tomorrow about GKC. At early check-in tonight I didn't see any robots that might have a problem with this sizing but I wasn't particularly looking for it, either.
dtengineering
14-03-2013, 02:15
What we can be sure of is that if any two points on the robot are more than 54" apart then they violate the rule.
There are also many machines that clearly are not in violation of the rule.
That leaves some "borderline" machines, but likely not many. It might be easiest to tape off a 54" circle, tangent to a wall, extend the appendage to touch the wall, and then place the robot inside the circle.
Just so long as we don't have that silly hoop back again. What year was it that we had the big hula hoop?
Jason
Tristan Lall
14-03-2013, 02:17
What we can be sure of is that if any two points on the robot are more than 54" apart then they violate the rule.
Unless they're not in a plane perpendicular to the axis of the cylinder....
tickspe15
14-03-2013, 02:45
In Portland there was a circle taped on the ground to set the robot in. Then a vertical board was run around the circle to make sure that no part of the robot extended out of the circle. I think they will use the same technique in ellensburg.
Jon Stratis
14-03-2013, 08:07
At Lake Superior, there were only a couple robots that warranted measuring - the others were all clearly within the limit. All but one of those measured didn't need any further looking, they clearly had more than an inch to spare with just some quick "napkin math". The other however was close enough that I felt the need to go further... I did a quick (less than 10 mins) CAD mockup with all the inportant critical dimensions to check it out.
At Lake Superior, there were only a couple robots that warranted measuring - the others were all clearly within the limit. All but one of those measured didn't need any further looking, they clearly had more than an inch to spare with just some quick "napkin math". The other however was close enough that I felt the need to go further... I did a quick (less than 10 mins) CAD mockup with all the inportant critical dimensions to check it out.
I'm just trying to get in an inspector's head, but if a team provided you with a CAD printout, would you have done your quick CAD anyway?
Jon Stratis
14-03-2013, 12:07
I'm just trying to get in an inspector's head, but if a team provided you with a CAD printout, would you have done your quick CAD anyway?
If the critical dimensions (length/width of each part, measurements of diagonals) were included on the printout by the CAD software and it was clear that everything fit within the cylinder on the printout, then no, I wouldn't have done my own CAD. I would have verified those critical measurements, however, to ensure that the CAD model was a valid representation of the robot in its maximum playing configuration... often what we design on the computer doesn't exactly match what's built!
LH Machinist
14-03-2013, 12:33
At our district event the inspectors used a 54" ID polycarbonate circle. The circle was halved and could be oriented in any direction, I assumed FIRST supplied it.
They used it and even told an inside climbing team they would be penalized if they started outside the pyramid (their climbing mechanism deflected when they went under). They played the elimination matches never leaving the inside of a pyramid.
Does the 54" cylinder include bumpers?
I was trying to determine this by reading the rules. G23 says the ROBOT must fit within the 54" cylinder.
The definition of ROBOT does not mention bumpers.
The definition of BUMPERS says they attach to the ROBOT.
That would make me think that BUMPERS are separate from the ROBOT and not included in the 54" cylinder for inspection.
tickspe15
14-03-2013, 14:56
Yes the 54" rule does include bumpers
Yes the 54" rule does include bumpers
Can you tell me how you reach that conclusion?
Jon Stratis
14-03-2013, 15:15
Can you tell me how you reach that conclusion?
https://frc-qa.usfirst.org/Question/44/questionlink
Q. Does the 54" diameter cylinder include the bumpers or not. R05 ambiguous.
A. Yes, BUMPERS are considered part of the ROBOT for [G23]. This will be addressed in Team UPDATE - 2013-01-11.
Yet when weighing the ROBOT, the BUMPERS are excluded from the weight for R05. And all through the rules ROBOT and BUMPERS are mentioned separately.
So only for G23 and G23-1 are BUMPERS considered part of the ROBOT.
OK, that clears things up :)
Jon Stratis
14-03-2013, 15:44
I don't make the rules, I just enforce them :) If there's a Q&A answer tomorrow that says "Per R196, every robot must have a carrot dangling by a string to indicate the front of the robot", I'll make sure I bring some carrots for those teams that missed it! If Frank is reading this, I'd love to see this rule... inspectors get hungry when running around to different pits all day, and having a natural snack built into every robot would be awesome! ;)
But in all seriousness, take a look at what the rule is attempting to accomplish. It's primary goal is to make climbing the tower a little more challenging, as that's really the only situation I've seen teams come close to hitting the limit. Part of climbing the tower involves the bumpers (how do you get them around the horizontal bars and avoid getting stuck?), so it only makes sense that, in this case, the bumpers are included in the 54" cylinder.
Kevin Leonard
14-03-2013, 15:57
Make sure that your robot doesn't go outside the cylinder during competition- even if it's not made to. Twice at WPI, 2791's arm broke when hanging (they have all their systems consolidated into one arm- its pretty nice). One of their gears got stripped, and they ended up outside the cylinder and were penalized a tech foul in both instances.
Joe Ross
14-03-2013, 16:34
Interestingly enough, the Q/A says that inspectors will use a Tape Measure (https://frc-qa.usfirst.org/Question/164/what-will-be-used-to-check-the-54-in-cylinder-size-at-the-tournament-ie-tape-measure-this-is-a-clarification-to-q162)
I think it would be nice if FIRST decided on rules which were more easily enforceable.
for example, wouldn't it be nicer to say:
"No two points on the robot may be more than 50" apart (horizontally), in any configuration"
This allows slightly bigger robots than a 50" cylinder, but notice that I reduced the number from 54" to 50". I think this would be more easily enforceable and still accomplish the general intent of the rule.
Retired Starman
14-03-2013, 23:31
At the Peachtree Regional (Georgia) today, we inspectors laid out a very accurate circle with blue painter's tape on the floor, 54 in. in diameter. This, we call, the Circle of Doom.
All robots during inspection must be placed within the circle. The back two corners are aligned with the circle (using speed squares if necessary). The any appendage is placed in it's maximum extension position and a long T-square is placed on the end of the appendage and flat on the ground. It quickly and accurately shows that the robot fits within the 54 in. cylinder.
Don't know how others do it, but this works and is real easy.
BEWARE, THE CIRCLE OF DOOM, ALL YE WHO ENTER!
Dr. Bob,
Chairman's Award is not about building the robot. Every team builds a robot.
All robots during inspection must be placed within the circle. The back two corners are aligned with the circle (using speed squares if necessary). The any appendage is placed in it's maximum extension position and a long T-square is placed on the end of the appendage and flat on the ground. It quickly and accurately shows that the robot fits within the 54 in. cylinder.
How do you handle situations when the 54" cylinder isn't perpendicular to the floor?
How do you handle situations when the 54" cylinder isn't perpendicular to the floor?
It has to be perpendicular to the floor when you're not in contact with the pyramid, so problem solved. It's also a lot harder to have a robot that doesn't fit in a cylinder when climbing, since there are infinite orientations for the cylinder to be and it only needs to fit in one to be legal.
Unless they're not in a plane perpendicular to the axis of the cylinder....
Ok, two points projected onto the ground plane then.
It has to be perpendicular to the floor when you're not in contact with the pyramid, so problem solved. It's also a lot harder to have a robot that doesn't fit in a cylinder when climbing, since there are infinite orientations for the cylinder to be and it only needs to fit in one to be legal.
This doesn't solve the problem if the part of the robot that goes outside of a perpendicular cylinder only extends when the bot touches the pyramid. You still have to find that one cylinder that fits. What I'm asking is how a circle on the floor helps with this? Do you have the kids hold the robot at various angles until you either find one or give up?
I inspected a bot at GKC where we used carpenter's squares and long pieces of square aluminium stock as a guide for my tape measure. We were able to find a cylinder that fit. If the team ever extends their climbing appendage while not touching the pyramid they'll violate the rule; no way around it. This was time-consuming and tedious; I would like to think there's a better way.
vBulletin® v3.6.4, Copyright ©2000-2017, Jelsoft Enterprises Ltd.