AC Servo Motor with different Feedback on AB Kinetix 350

[Chris Elston 78]

I don't know too much about this topic, so I thought I would see if anyone else did. I wanna do something crazy. I have an existing AC servo motor with a resolver feedback device. I have space and the means to connect an external encoder (verses a resolver) to a linear slide with said AC Servo motor. I'd like to use the motor portion of the AC Servo motor (pending it's compatility with AB Kinetix drive), and the external shaft encoder (instead of the resolver). It must be an encoder type for the AB Kinetix drive. So the resolver leads on the AC servo motor will be dead or unconnected, and the new external encoder will be on the same shaft as the AC servo motor. My AB motion expert, which I believe him, says it's critical to align the encoder to the rotors on the motor in order for my crazy idea to work. Can any one give me more of a background on this? I don't understand the theory behind that 100%. If I did, I think we have the means of aligning the external encoder to the AC motor if I understood why this is so critical. After this alignment, it seemed to be it was possible to do this. Any thoughts?

[michael G 2]

AB Kinetics Servo have Dual Encoder Modes - Default is Position Control - one encoder I think that the mode that you are looking for is Dual Position Controller - One resolver for the motor another for the application, Motor one looks after all the alignment stuff, the other one is for your application and can compensate for backlash etc Motor Alignment - I have been given a AB Kinetics motor that had the wrong alignment setting - Torque was reduced to 30% of what a correctly aligned motor could do. Michael

[drforsythe 15]

The feedback device on a servo motor serves two purposes: 1) position feedback for the application and 2) position feedback for commutation. Commutation is the most important function. Without this 'alignment' the servo amp cannot properly control the torque, speed and direction. Does AB have a way to determine or set the proper alignment? If so, I would like to see what procedure is used.

[JRoss 84]

The Kinetix Drives have an Auxiliary Encoder Input that I believe you can use for "Full Loop Control", which is what Michael G is talking about. I would take your linear slide into that and leave the resolver on the main encoder input. Assuming the servo motor is compatible with the Kinetix, you'll have less headache that way. You'll also want to have a very low-backlash mechanical system to get good positioning control without a lot of oscillation and noise.

[Chris Elston 78]

I guess this is my same exact question. Does anyone know how this is done? As far as the other things. I don't plan on using the resolver, I was going to leave that unconnected because it's not compatible with a Kinetix 350. I was planning on only using the external encoder and the motor leads only. So in regards to that, I wondered the same, what is the procedure to align my external encoder to the motor? How is this done?

[michael G 2]

Try this for information Ohh there is heaps of stuff that can go wrong