Design and Implementation of a High Bandwidth Servo Controller for Micro-Machining Center

To achieve the required performance of a Micro Machining Center, the control system must issue position commands with nanometer resolution, while holding the axis position with oscillations down to sub-micron level. The requirements call for a highly flexible CNC platform with unconventionally high-bandwidth servo controller. In this paper, we present a system-wide design based on an open CNC architecture with integrated digital servo drives. The proposed design incorporates customization of the digital protocol between CNC and drives, ultra-fine interpolation of the encoder signal, and novel approaches to increase the servo-loop bandwidth. A three-axis Micro Machining Center was successfully built with the proposed design, which was then proven to meet the stringent requirements with extensive dry-run and cutting experiments.