Analysis of mutual influences of control, feedback and servo drive systems for ultra precision machining

The mechanical design of ultra-precision machine tools is very well understood today. Detailed investigations on precision axes designs, dimensioning of bearings and drives and overall machine concepts have built a broad basis for designing very stiff and accurate state-of-the-art machine tools. Enhancements to further increase the achievable form accuracy and surface quality and at the same time decrease cycle times and error sensitivity can only be accomplished by innovative control and drive systems. In contrast to mechanical machine design, control, servo drive and feedback as well as their interactional behavior within a complex machine setup have not been sufficiently analyzed yet. This applies especially to ultra-precision machining. At Fraunhofer IPT a test bench has been developed to analyze machine controls, servo drives and encoder and sensor systems with regard to an evaluation of capabilities of their application in an ultra-precision lathe. This paper will give a summary of the results of servo drive and linear encoder analysis including both a comparison of individual components and an investigation on mutual interactions.