Manipulators: Claws vs rollers?

[JesseK]

The little VEX wheels are almost ideal for a primitive roller claw. Thank goodness they're legal!

We had a very long discussion this weekend about pickup mechanisms. We listed a couple of observations as we acted out retrieval from the opposite side of the field:

• Acquiring from the chute in the wall means the tube will most likely need to be reoriented at some point to prevent it from being inadvertently 'stolen' while crossing the field since it sticks out
• Acquiring from the ground while in that lane is very difficult due to the wall that divides the lane and the opponent's scoring zone. This 12" wall makes it very difficult to accurately line up to a inflated tube that's only 9" high from ~50 feet away
• It's very easy for opponents to 'snipe' a tube that's thrown outside of the lane just by blocking the path to the tube, then going for it (much like blocking out in Ultimate Frisbee)
• It's very difficult to throw a tube in the lane to a place the drivers can see with much consistency

The thought came up that we need some sort of 'garbage chute' that the HP can dump the tube in and our mechanism can retrieve from. Yet we're running out of room and weight on the robot, heh.

So we're going to stick with a simple claw that only picks up from the ground, for the moment. We need to think some more. It was the first time we'd really considered roller claws; however they add an entire layer of complexity in control on top of an already somewhat complex control system (lift + wrist + simple claw will keep a driver very busy as-is).