Due to recent technological trends in high-speed, high-acceleration NC machine tools, the vibration control for a feed drive system in NC machine tools is regarded of more importance. This paper presents a tuning methodology of a fixed-structure feedback controller for the damping control of feed drive systems. Unlike celebrated optimal control theories, the present tuning methodology is based on a local search algorithm, and thus cannot always guarantee to find the globally optimal solution. However, it offers much more flexibility on the setup of the tuning objective and constraints, which is crucial for practical controller design. As an application example, the tuning of a fifth-order linear feedback controller for a feed drive system in an NC machine tool is presented. Unlike a notch filter, which is often used in conventional CNC units to cancel the mechanical resonance, the designed controller does not introduce much phase lag into the feedback loop, and thus offers a better closed-loop control performance.

Keywords:   Controller tuning, damping control, numerical optimization, feed drive systems, frequency-domain loop-shaping design