This paper presents a novel sensing technique which uses a piezoelectric strain sensor for damping and accurate tracking of a nanopositioning stage. Piezoelectric elements have been used effectively as sensors for vibration control of smart structures. However, complications arise when one uses a piezoelectric strain sensor in a feedback loop for tracking. This is due to the high-pass characteristic of the piezoelectric strain voltage at low frequencies which tends to destabilize a closed-loop tracking system. Here, we overcome this problem by using a low-frequency bypass technique which replaces the low frequency signal with an estimate based on the open-loop system. Once the high-pass characteristic is accounted for, an analog Integral Resonant Control (IRC) and an integral tracking controller were implemented. The resultant tracking bandwidth of the closed-loop system was measured to be 1.86 kHz. To evaluate the closed-loop tracking performance of the nanopositioning stage, it was forced to track triangular waveforms at 40 Hz and 78 Hz. The closed-loop system shows significant improvement where the non-linearity of the system is effectively reduced.
1st International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale, 2011 (3M-Nano 2011). Proceedings of the 1st International Conference on Manipulation, Manufacturing and Measurement on the Nanoscale 2011 (Changchun, China 29 August - 2 September, 2011)