ResearchFields

This project focuses on the design, identification, and control of a novel, flexure-based, piezoelectric stack-actuated XY nanopositioning. The main goal of the design is to combine the ability to scan over a relatively large range (25x25 \mum) with high scanning speed. Consequently, the stage is designed to have its first dominant mode at 2.7 kHz. Cross-coupling between the two axes is kept to -35 dB, low enough to utilize single input-single-output control strategies for tracking.

The objective of the project is to design an AFM scanner with the ability to scan an image at high-speed and high resolution. Finite-element analysis was used to optimize the scanner's design in order to achieve high resonance frequencies. Experimental results show that the scanner has resonance frequencies of 10kHz at the X, Y and Z axes.

A piezoelectric tube scanner with a novel electrode pattern was developed for simultaneous actuation and sensing. The electrodes are arranged such that the tube is driven in an anti-symmetrical manner resulting in a collocated system suitable for feedback control.

Feedback control strategies with low sensitivity to measurement noise are considerably important in many applications, especially in nanopositioning. This project concerns the development of a novel control approach, named 'Signal Transformation', which can provide a noise rejection performance much beyond the limitations imposed by ordinary methods. In this method, appropriate transformation mappings are incorporated into the ordinary feedback control loop to achieve better tracking performance while the closed-loop bandwidth is kept low. A low closed-loop bandwidth is necessary for high precision control when impact of sensor noise or un-modeled dynamics on the output is substantial compared to the desired resolution.