PDA

View Full Version : More MX-64T woes: One doesn't keep position; the other doesn't listen



jwatte
04-01-2013, 09:13 PM
I'm still having some problems with two of my MX-64Ts.

One of them (call it number 7) doesn't quite keep its position. When I tell it to stand still at 2700, it stands there for a few seconds, then moves a few degrees one direction, then stands still for a little bit, then moves a few degrees the other way, stands still for some random time more, ... This sounds like an encoder problem, perhaps?

The second (call it number 2) doesn't want to hear commands or respond to read requests when it's in a string with other servos (it's on a string between servo 1 and servo 3, which both work fine.) When I use it alone with a USB2Dynamixel, it works. So, I wonder if my TTL driver is not strong enough. My driver is a Atmega32u4 with a 70 Ohm resistor wired from TXD to the serial bus, where five parallel strings in turn are driven; four with three servos each, one with two servos. Power is separately provided to each string to avoid too much sag because of wire length. Given that the servo after the non-listening servo works, I don't *think* this should be a problem, but I don't have a scope to verify with for sure.

Are these servos just flaky? Should I try swapping in others? Could I have damaged them somehow? These are new, or recently returned from Robotis with a fixed circuit board. The robot has just been sitting on a pedestal, or taking a few steps on an indoors living room/corridor floor.