Motoman K6SB Retrofit

Huh I actually had not seen that one! Several years ago I tried to figured out the genserkins config for my puma arm before giving up and eventually finding an out of the box puma config that worked; with this page though I actually have a hope of doing it from scratch, or like you said, just replacing the link lengths.

Thanks a ton!

Anybody by chance know the harmonic drive ratios on these arms? Or know which document would contain them? I’m told they are params in the ERC controller, but since I lack said controller that doesn’t help me much :-/

That’s a good idea, thank you.

I guess what set in my mind that DH params would be hard to deduce on my own is that my PUMA arm has mechanical mixing (wrong term?) in the wrist- moving either of the involved servos alone causes both a twist and a bend of varying rates; to move only one joint, both servos need to move synchronously at different rates.

Unrelated- I was planning to use a mesanet real-time ethernet board for this, since I have one on my mill conversion and it’s very good. I see the original poster is using ethercat- is that something I should look into / any advantages?

If I keep the stock AC servos in the arm, AND I can figure out the encoder startup commands with a logic analyzer and a working controller, AND I can hack said commands into linuxcnc, I will need to pwm “dumb” drives (3 half bridges per servo) and do the phasing in software (since the only feedback from the servos is the absolute encoders- no halls or resolvers near I can tell).

If I replace every servo in the thing with a BLDC, I can either do the same thing (half bridges and phase control in HAL/linuxcnc), or use off the shelf drives, feed them halls and +/-10vdc (lowpassed pwm), and just bring the encoders back to linuxcnc.

Any thoughts / hints on the three-halfbridges method, or other ideas?

That is not a bad idea- I’ll read about his stuff, thanks. I don’t know anything about yaskawa drives but they are def widely available on ebay and I can probably find their docs. I agree it’d be much less work to use them than replumb everything.

i'm not that good with yaskawas... if it happens that the original drives are using mechatrolink then i can probably control them. otherwise i don't know how to convince newer yaskawa drives to recognize older/non-standard motors...