# AKD Servo Driver Controller Logic Questions

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I have some technical questions with regards to the AKD Servo Driver Controls System. The core of my problem is that I am trying to integrate some servo motors into a complex non-heuristics based system, and as such need to be able to create an accurate simulation of our system response. That response also entails knowing exactly how the drivers behave when we supply them with a command value.

I have looked at the Kollmorgen Online Workbench, which has been helpful in letting us construct a simplified version of the control system. However, I am having a difficult time getting an appropriate response out of our system. The main thing that would solve all of my problems is a conclusive set of block diagrams that describe the embedded controls logic, so that way I can base everything off of that single diagram, instead of off the various smaller diagrams listed on the online manual.

Is there anything like that anyone here can provide me with? If not, these are my three core questions:

1. I noticed that the system is built so that it takes a commanded velocity and compares it to last sample's feedback velocity in order to apply the appropriate current. However, the velocity delta (the difference in velocity) seems to imply that the commanded current output of the velocity loop is actually the commanded current delta output. Is this correct? As in, does this value plus last time's current output equal the effective commanded current, which is the input for the current loop?
2. In addition, how does this component interact with the current feedback from the last loop? The diagrams for the current loop seem to imply that the current loop outputs a zero value when the commanded current is identical to the current feedback, which suggests that the system would oscillate continuously between zero and full speed under steady state. Can anybody clarify how these components interact?
3. I have come to understand that the bode plot of the plant found in the Auto-tuning process symbolizes the transfer function between the Voltage applied to the motor and the physical response of the plant. Does this imply that the units of the transfer function are radians per second-Volts? Or, if I'm wrong and the transfer function input is based upon the current supplied, does that make the unit radians per second-Amps? Or am I misunderstanding entirely, and the plant transfer function here means something entirely different?