Who can help me with finding training documents about the working principle of servo motors in combination with a absolute positioning encoder??
Maybe you'll find some information from the manufactures of servo motors. Try sanyo denki.
There is also open source project for these things like robotics and there is also some documentation.
FYI, they may have changed to orocos.org if not already there.
>There is also open source project for
>these things like robotics and there is
>also some documentation.
Absolute encoder makes little (if any) sense for DC motor speed control. It is too expensive and incremental encoder or tacho will do the job.
Absolute encoder is good for position control applications with sinusoidal brushless servo motor that requires position initialization at power-up. However, it can be replaced by incremental encoder and a proper initialization (phase search) procedure - see, for example, the following threads with some references:
I hope that "absolute position encoder" means modern high resolution interpolated sin/cos encoder with serial interface.
You may find asked info from encoder's producers (Stegmann, Netzer, Heidenhain) or IC producers (icHaus, Texas Instruments Analog devices). Pay attention that resolver, synchro and even potentiometer suit for above term.