Design, Identification, and Control of a Flexure-Based XY Stage for Fast Nanoscale Positioning

The design, identification, and control of a novel, flexure-based, piezoelectric stack-actuated XY nanopositioning stage are presented in this paper. The main goal of the design is to combine the ability to scan over a relatively large range (25 x 25 Am) 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. Finite-element analysis (FEA) is used during the design process to analyze the mechanical resonance frequencies, travel range, and cross-coupling between the X- and Y-axes of the stage. Nonlinearities such as hysteresis are present in such stages. These effects, which exist due to the use of piezoelectric stacks for actuation, are minimized using charge actuation. The integral resonant control method is applied in conjunction with feedforward inversion technique to achieve high-speed and accurate scanning performances, up to 400 Hz.