Pic: would this chassis shape be legal?

[ssa3512]

Originally Posted by Creator Mat

I think it is legal because the ball would be free to move within the indentation area and thus would not be possession. I want to find out what the rest of the FIRST community thinks. Also if you think this would break a bumper rule or some other rule beyond just the no possession rule please say something.

I believe you misread the rule on "Possession" and are confusing with "Carrying"

<G43> ROBOT BALL POSSESSION - ROBOTS may POSSESS only one BALL at a time. Violation: PENALTY.
<G44> BALL CARRYING – ROBOTS may not CARRY BALLS. Violation: 2 PENALTIES for each CARRIED BALL.

Possession refers to keeping the ball in the same position relative to the robot when turning the robot, etc. The ball is still in contact to the floor. This is legal.
Carrying is where the ball is possessed by the robot AND off the surface of the floor. This is not legal.

The rule you need to worry about is as follows

<G46> BALL Penetration Restriction – The BALL must not extend more than 3 inches inside the FRAME PERIMETER as defined in Rule <R19>. Violation: PENALTY for a basic infraction, plus a YELLOW CARD if no immediate attempt to remedy.

FRAME PERIMETER – the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string describes this polygon.

In your design, the FRAME PERIMETER is a rectangle, even though you have that indent on the one face of the robot. The ball would not be allowed to penetrate more than 3 inches into that rectangle. Hope this helps