Which motion control method has been "ServoJ" used?

Technical Questions URScript
1

Hello every UR+ experts,

I have used UR script command “ServoJ” in a visual servo project, and it really have an excellent performance. But i want to try some state-of-art control strategy and compare their with UR default one(which the servoJ is using). therefore, could you give some information about:

  1. what motion control method is ServoJ using, is PD, PID or some enhancement PID.

  2. if you can’t explain it because some company regulation, could you give me some hints about which paper you are referring(the parper name or a DOI of this paper).

I have scanned through the UR manual and UR+ forum, and i can’t find some document about it. so, if you could reply me, it’s much appreciated.

Sincerely.