Quick question. What difference would it make if for a 6 bar lift we had the geared bar on top of our gear tower and a free spinning one in the middle instead of the other way around?
Should work about the same either way. Maybe the loading is different with a six bar, but I don’t think so? If you drive any link of a linkage, the rest of the linkage moves in a predictable fashion. The main reason moving the bottom link is preferred is because it puts the weight of the gear train + motor in a lower position on the robot, slightly lowering CG and shortening wire lengths etc.
Powering the bottom bar also lets you put a motor above and below that bar’s gear as a method of powering it with two motors.