Virtual vibration absorber for active forced vibration reduction

Forced vibrations caused by unbalance can negatively impact the surface finish of high-precision grinding. This paper presents a model-free virtual vibration absorber control law, which effectively reduces vibration levels by emulating a physical vibration absorber. The control law's tuning parameters can be adjusted in real-time to track the spindle frequency, ensuring the excitation frequency always matches the anti-resonance created by the virtual vibration absorber. The control law is first experimentally validated on a flexure and then applied to a high-precision vertical grinding machine achieving a reduction of the forced vibration amplitude due to spindle unbalance by up to 85%.