Hi guys,

I just recently found an old robot arm abandoned in the company. It has Sanyo Denki AC servo motor controlling its joint. There is no servo amp and no controller that come along with it. 2 of the servo has an absolute encoder and 1 has a incremental encoder. Encoder alignment is questionable at best. I also have on my hand a mitsubishi servo amp.

After some reading up in the past 2 or 3 weeks I get my brain tied up in a knot, and need some help understanding how all these things works together.

Let me know if I am on the correct understanding...

1. Theoritically servo motor are just a plain dumb motor, DC brushed servo motor is just normal dc brushed motor with some sort of encoder attached to the shaft. Brushless motor is brushless motor, DC brushless or AC brushless is just about how the servo amp send out the signal to spin the motor.

2. For brushless motor, the servo amp needs information on how to send out the signal, i.e. commutate the motor. They get this signal either from a resolver, a hall effect sensor (for BLDC), incremental encoder or absolute encoder.

3. Brushless servo motor need to have their encoder/resolver/hall effect sensor aligned to the stator winding to give best torque characteristic.

So that's what I think I know from my google-fu, next are my questions, most of them revolve only around brushless AC motor...

1. Is there any reason why I can't just grab a servo amp that can have the configuration of the encoder/resolver set up in the software and get this servo amp to drive just about any servo motor ?
2. I seen some specialized equipment and technique required for encoder alignment. Is it correct again, to assume that as long as I set the servo amp to correspond to the correct encoder type installed in the motor, I can do encoder alignment by aligning the zero pulse (for inc enc) or pos 0 (abs enc) to one of the motor natural position and once I get it somewhat correct (i.e. motor start rotating to the correct direction) I can then start to adjust the encoder position slowly and aim for maximum torque ?
3. Or if the servo amp has configuration data on where is the encoder alignment then we can just adjust this again till we get max torque ?

Thanks for all the help. Once I gain a little bit of more knowledge, my aim is to start this robot with a mishmash of different servo amp that I can lay my hand on, and try to get it moving.

Regards,
Leonard