I'm working on a project using hobby servos to drive a revolute joint, and the servo mechanism doesn't seem to respond when I command a motion of less than about 1 degree. I want to increase the resolution without sacrificing range (otherwise I would just gear them down).
I've read that "parallel" robots such as delta-style 3D printers or pick-and-place machines are generally much more accurate than "serial" robots like a typical robot arm. Is there a linkage design which can combine the motion of two servos into a single "better" rotational actuator? The output would still just have one degree of freedom, but increased resolution compared with a direct coupling to one servo.
First I thought maybe you could reduce the motors by 2:1 and then add their outputs somehow, but it seems like this would also add the positional errors together, and you wouldn't gain anything:
Then I thought about it a bit more and came up with this arrangement, with a parallel linkage between the two motors fixed at a point between them.
I have no idea if this would actually improve my resolution though. Would I need to command different positions to each motor? e.g. if I want to achieve 90.5 degrees, would I command 90.0 to one motor and 91.0 to the second motor? Or is there a better way to approach this? (I realize I could just buy more expensive servos, but I'm trying to work with what I already have).