Three joint arm

[Mark McLeod]

Here's a short clip of our 3-jointed arm from 2007. The controls were fairly simple, because for that game most of the joints could be slaved to the position of a master joint. So the arm driver just specified where the tip needed to go and the rest of the arm followed.
There was a tightly constraining 80" cylinder written into the rules that year, so the software managed all the joints to keep the whole arm within that imaginary cylinder.

The arm was modeled and controlled in Vex first to test the control logic.

[Lil' Lavery]

My personal design philosophy is single-joint or bust. Simpler to build, easier to control, easier to program, fewer points of failure, and require fewer motors (and speed controllers). There are plenty of other options to increase an arms "reach" other than adding more joints.

I do appreciate the desire and lessons that can be learned from taking this on as an off-season project, especially in regards to the control perspectives.

[JosephC]

68's robot from 2011 had 3 joints (well 2 and 1/2; we had a shoulder, a elbow, and could flick our "wrist".)


Skip to 2:57 for the arm, sorry I couldn't find any better pictures. They're all at school.
http://www.youtube.com/watch?v=QWKMNXKR7Ns