Invitation for opinions on 3" engagement rule
 

We are having some post-ship contemplation on the possible interpretations of the 3" engagement rule. I realize this topic has already been discussed thoroughly, but we had a certain interpretation to invite comment on.

If you have a "V" shaped inclusion with the V opening upwards such that the ball can rest in it by more than 3", this is certainly a violation of the engagement rule. If you turn that same "V" shape 45 degrees so that one leg is vertical, you have changed the orientation of the situation, but technically the ball is still engaged by the geometry of the robot by more than 3" (see pic). The rule does not say anything about the orientation of the engagement, or what the orientation is with respect to the floor or gravity.

So, does this mean that a flat top or even a domed or sloped top cannot intersect a vertical feature if the vertical feature is tall enough for the resulting "V" engagement to be more than 3"? There are certainly some finished robot designs out there which would violate if this is the case. This is related to but separate from the issue of whether the vertical "V" shape feature might control or "carry" the ball when the robot is in motion.

Re: Invitation for opinions on 3" engagement rule
 

I think it will be clear that your proposed scenario will not be legal. check out the FRAME PERIMETER rules and think about how you could legally create such a device inside the frame perimeter and yet not allow a ball 3" under the frame perimeter.

The robot footprint is defined by the FRAME PERIMETER and you can't have the ball more than 3" under that. Your FRAME PERIMETER is defined inside the BUMPER ZONE which is above the height of a ball, so you can't do this without violating the FRAME PERIMETER.

Just my thoughts.

Rob

Re: Invitation for opinions on 3" engagement rule
 

We meant above the bumpers. Sorry, not specified.

Re: Invitation for opinions on 3" engagement rule
 

i think the rule you are looking for is this:

<R19> ROBOTS must be designed so that in normal operation BALLS cannot extend more than 3 inches inside
a) the FRAME PERIMETER below the level of the BUMPER ZONE (see Figure 8-5),
b) a MECHANISM or feature designed or used to deflect BALLS in a controlled manner that is above the level of the BUMPER ZONE.

does this help?

Re: Invitation for opinions on 3" engagement rule
 

That is the rule in question. The intrepretation as described above is the question.

Re: Invitation for opinions on 3" engagement rule
 

a GDC answer to a question regarding a similar situation:

The prohibition in Rule <R19-B>, as amended in Team Update 2, is against BALL incursion inside any particular MECHANISM on the ROBOT. It is understood that the BALL may enter inside the vertical project of the FRAME PERIMETER of the ROBOT (i.e. be "inside" the ROBOT boundaries). A situation where the BALL traverses "inside" the robot boundaries (e.g. as it falls from the BALL RETURN and bounces off the top of the ROBOT), but does not enter a MECHANISM by more than the permitted 3 inches, would not be PENALIZED

my interpretation of this combined with updates #2 and #9 is that unless the "V" shape is designed to manipulate the ball, then it is legal.
in my opinion, unless you have a complete "cage" around every part of your robot to block the ball, a ball will enter the frame perimeter more than 3".

Re: Invitation for opinions on 3" engagement rule
 

The way we interpreted this, any part above the bumpers that has the effect of benefically controlling the direction of a ball, whether intended solely for that purpose or not (roll bars on each end of the robot, etc), would form the "boundary" for the 3" dimension. Parts that stick out but are not beneficial to ball control (a thin arm for a lifter, etc.) would not define the 3" boundary. This is just our opinion, for what its worth. The ref's make the call.

We have roll bars and an angled deflector plate on the top. We arranged things to make sure that the deflector plate stayed within 3" "boundary" defined by the roll cage.