Q&A response - new interpretation of R16

[dlavery]

Originally Posted by EricH

Yes! No cylinder! (They have effectively declared a square, but your robot must fit in it in any orientation.)

No they didn't. Read the Q&A answer again.

The rule is exactly the same as it was when it was written. An 80-inch square would have a diagonal measurement of 113.14 inches, which is a clear violation of the rule.

-dave

[AdamHeard]

Originally Posted by dlavery

No they didn't. Read the Q&A answer again.

The rule is exactly the same as it was when it was written. An 80-inch square would have a diagonal measurement of 113.14 inches, which is a clear violation of the rule.

-dave

Out of curiosity; who's maniacal idea was it to have the 80" rule?

[jgannon]

Originally Posted by dlavery

No they didn't. Read the Q&A answer again.

Dave, read Eric's post again. He's saying that the bounding box is a square, but your robot must fit in it in ANY orientation. If you can fit such a square regardless of your orientation, then you are within <R16>. If there is some orientation such that you don't fit, then you are violating <R16>. As such, Eric's definition is precisely <R16>.

[Lavapicker]

I'm still confused....does that mean we can have an arm that reaches out to 80 inches, as measured from the back of the bumber, and still be ok? That's the way I read it and then I see the Cylinder thing which contradicts it. Is there a definitive answer?

[MrForbes]

There is a definitive answer, but it's a bit hard to understand, apparently

If your measure from the end of your robot arm to either end of the back bumper, and it is more than 80", then you violate the rule.

In the case if the end of the arm is just under 80" from the center of the rear bumper, and the arm extends straight forward from the center of the robot, it would voilate the rule when measured from the ends of the bumper.

Make a sketch....post it...we're very good at arguing about stuff we can see.

[MCahoon]

Definition of ANY is "one or more". Using Eric's definition, if your 'bot fits corner to corner diagonally, your good. Properly it would have to fit into the box in EVERY orientation.

[dlavery]

Originally Posted by jgannon

Dave, read Eric's post again. He's saying that the bounding box is a square, but your robot must fit in it in ANY orientation. If you can fit such a square regardless of your orientation, then you are within <R16>. If there is some orientation such that you don't fit, then you are violating <R16>. As such, Eric's definition is precisely <R16>.

Nope, I still don't agree. Eric's definition is much too permissive. If the explanation had been "must fit in an 80-inch square in every orientation" then I might buy it. But not as written.

Originally Posted by MCahoon

Definition of ANY is "one or more". Using Eric's definition, if your 'bot fits corner to corner diagonally, your good. Properly it would have to fit into the box in EVERY orientation.

Yeah, that is exactly the point.

-dave

[jgannon]

Originally Posted by dlavery

Eric's definition is much too permissive. If the explanation had been "must fit in an 80-inch square in every orientation" then I might buy it. But not as written.

Mea culpa. Your definition is unambiguous. Thank you, Dave.

[Tristan Lall]

I just wanted to point this out: the equilateral triangle isn't really the limiting case for a 3-sided figure. It's actually the curvilinear triangle with a width of 80 in. It has more area, for a given width.

Also, the triangle isn't the only figure for which this works: see here for an applet that demonstrates the principle for odd numbers of sides, from 3 to 21.

So, who's going to build a robot that fits a curvilinear pentagon, just to annoy the officials?

[Kims Robot]

Originally Posted by Tristan Lall

So, who's going to build a robot that fits a curvilinear pentagon, just to annoy the officials?

I guarantee someone will need something other than an equilateral triangle or a circle to fit (heck my team may even try it to make our programmers lives easier - last year we made them take an 86" jointed arm and contstrain it to 72" at all times through feedback on our sensors!!).

But what I want to know is is this going to be in the referee training... keep your Q&A and rulebooks on hand if you really want to nitpick this rule!!

[Gdeaver]

This is a bad rule. Even with a Q and A response it's still gray to teams. On the field with a fast moving wide open game this year , refs will have a difficult time enforcing the rule. I predict many teams will violate it and get away with it. There is still time for the rule to be modified so that teams can more easily comply and make the refee's job easier.

[EricH]

Originally Posted by Gdeaver

This is a bad rule. Even with a Q and A response it's still gray to teams. On the field with a fast moving wide open game this year , refs will have a difficult time enforcing the rule. I predict many teams will violate it and get away with it. There is still time for the rule to be modified so that teams can more easily comply and make the refee's job easier.

Remember the similar rule from last year? How do you determine whether a team is in the box? There were infractions last year that apparently weren't called, even on the diagonal part. This year at least means that the refs don't have to call on diagonals. They have one standard size. So some teams slide through. It's part of the game. I've seen soccer games where the ref saw a hand ball and didn't call it. As long as the rules are applied evenly to all teams at the event (and, ideally, all events), I don't really care.

[AdamC]

Checking that article about curvilinear triangles (please don't harangue me for steering away from the original topic), does anybody know of a company that sells a curvilinear drill bit? It would be useful for drilling holes and then mounting a square locking pin as opposed to cutting notches and then mounting the pieces together (which changes the size of the bar stock). I suppose if they don't exist, I'll try and make one myself.

[jgannon]

Originally Posted by AdamC

Checking that article about curvilinear triangles (please don't harangue me for steering away from the original topic), does anybody know of a company that sells a curvilinear drill bit? It would be useful for drilling holes and then mounting a square locking pin as opposed to cutting notches and then mounting the pieces together (which changes the size of the bar stock). I suppose if they don't exist, I'll try and make one myself.

I don't totally understand the geometry behind it, but the second sentence in the linked article was "No - you can't drill square holes", so I'm guessing there's some reason that doesn't work.

[MrForbes]

look at what happens when you start drilling a hole in a piece of metal, with a relatively large drill bit, like 1/2", using a handheld drill. Often the hole will start out with 3 curved sides, even though the bit has only two cutting sides. I think this is sort of what you're thinking of?

so try a 3 sided bit to make a square hole.