Colloquia

Summary

Performance of precision mechanisms in the high-tech industry is limited by disturbing vibrations. Over the last years, developments have been made in the use of piezoelectric patches, integrated with flexures, in order to actively suppress vibrations in various structures. By interconnecting the patches with a positive position feedback (PPF) controller, Seinhorst et al. showed the potential of suppressing parasitic eigenfrequencies. This work aims to extend this technique to a 6 degrees of freedom problem, where the goal is to suppress the nominal eigenfrequencies of a flexure-based vibration isolation system. The active approach does not suffer from the trade-off inherent to passive damping; where vibrations at eigenfrequency are suppressed at the cost of deteriorating performance at higher frequencies. In this work a flexure based isolation system is designed with 6 integrated bimorphs, with the nominal suspending frequencies between 10-22 Hz. Using system identification in the frequency domain and structured parameter estimation, the mode shapes and state-space matrices are derived. Using modal decoupling the 6 DoF MIMO control problem is transformed to 6 SISO problems. For each nominal mode, a PPF controller is tuned. The active vibration suppression scheme was implemented successfully, increasing modal damping from 1% to 13%. The results support the potential of implementing piezoelectric damping in many other industrial cases.