[dhitchco]

I like the "conveyor belt" idea. Just think of a chameleon's tongue and the number of ways you could grab onto a tetra!

But, back to reality and the ways to grab a tetra?

1) Forklift it from underneath
2) Grab it fromthe top of the apex (ala a crane)
3) Spear it inside and lift from UNDER the apex
4) Suction the tetra on one side (perimiter only)

Just remember that the tetras won't always be aligned exactly the same even if you approach it in a parallel fashion:
a) tetras on the field floor will angle away from your robot
b) tetras in the auto-loader wil be perpendicular to the front plane of your robot
c) positioning a tetra on a goal can be done at a variety of angles
d) tetras UNDER a goal can be any which-way
e) manually-loaded tetras will be very unpredictable

BUT, there are ONLY three vertical elivations you need to worry about: floor height, loader-height, and goal-top stacking height. Anything in between these three is not a critical dimension.