Robust digital tracking controller design for high-speed positioning systems-a new design approach and implementation techniques

This paper offers extensions to a previously proposed and implemented robust digital tracking controller design for a high-speed positioning system. The previous design exhibited excellent tracking performance in spite of friction and parameter variations in the plant, but required the use of a high performance CPU and a high-resolution feedback encoder. In this paper, a new discrete-time design method is proposed to relax these requirements. Experimental results show that similar levels of tracking performance can be achieved at slower sampling rates. Further, difficulties associated with controller parameter scaling are reduced. Finally, sensitivity to low-amplitude high-frequency limit cycles due to encoder quantizing errors are reduced in the new design.