Articulated arm vs Forklift style arm

[JesseK]

Fork-Lift
Pros:
- Compact, even in the scoring zone
- Consistent positioning in the y & z axes in relation to the scoring
- 1 Sensor can determine multiple positions
- Extremely simple to adjust height for minor corrections

Cons:
- Must be very rigid to prevent torsion & binding when the lift is at maximum height
- Generally heavier due to (typically) multiple stages
- Requires upkeep every match -- PROPER tension on cabling, cabling remains on pullies, ensuring the winch hasn't jumbled the cabling, etc
- If linear slides are used, they limit the ability to powder-coat (not a con for most in FRC, however in the real world this is a consideration since EVERYTHING must deal with corrosion if it's a long-lasting product -- so we teach it to our students as well)

Rotating Arm
Pros
Simple to build if it's 2 joints
Very easy to program so long as the joints are geared slowly enough (standard PIDs)
No need for a braking mechanism if it's geared enough (due to lightweight game piece this year)

Cons
- The drivers have to be different distances from teh scoring pegs depending on how high the arm is
- It must be 2 joints to reach a game piece on the floor (most 2007 designs make the bumper configurations illegal under 2011 rules)
- Different orientations of the shoulder joints may cause undesiered re-orientations of the game piece -- in 2007 many teams took advantage of it (see 330's diagram in the Behind the Design book) yet this year that's a bit more difficult (IMO).