Optimal Sensorless Shunts for Vibration Damping of a Piezoelectric Tube Nanopositioner

摘要

Piezoelectric tube scanners are the main form of actuation in scanning probe microscopy. These nanopositioners have a dominant first resonant mode. This mode gets excited due to harmonics of the input scan signal and introduces errors in the scan obtained. In precision scanning applications, this limits the upper bound of a triangular scan rate to around 1/100th the first mechanical resonance frequency. Shunt damping has been explored as one possible way to damp this resonant mode and improve scan performance. In this work, we design active shunts optimized using H_2 and H_∞ techniques. These shunts damp the modal amplitude of the first resonant peak by 24dB. A triangle raster pattern used to test the scan accuracy shows significant improvement due to the damping achieved by these active shunts.