Integrating Active Damping with Shaping-Filtered Reset Tracking Control for Piezo-Actuated Nanopositioning

TL;DR

This paper introduces a dual-loop control architecture combining active damping and a shaping-filtered reset tracking controller to significantly enhance the bandwidth and performance of piezoelectric nanopositioning systems.

Contribution

It proposes a novel dual-loop control method integrating a resonant controller with a reset element and a shaping filter to improve nanopositioning accuracy and bandwidth.

Findings

Achieved approximately 55 Hz increase in open-loop crossover frequency.

Improved closed-loop bandwidth by about 34 Hz.

Demonstrated effectiveness on an industrial piezo nanopositioner.

Abstract

Piezoelectric nanopositioning systems are often limited by lightly damped structural resonances and the gain--phase constraints of linear feedback, which restrict achievable bandwidth and tracking performance. This paper presents a dual-loop architecture that combines an inner-loop non-minimum-phase resonant controller (NRC) for active damping with an outer-loop tracking controller augmented by a constant-gain, lead-in-phase (CgLp) reset element to provide phase lead at the targeted crossover without increasing loop gain. We show that aggressively tuned CgLp designs with larger phase lead can introduce pronounced higher-order harmonics, degrading error sensitivity in specific frequency bands and causing multiple-reset behavior. To address this, a shaping filter is introduced in the reset-trigger path to regulate the reset action and suppress harmonic-induced effects while preserving the desired crossover-phase recovery. The proposed controllers are implemented in real time on an industrial piezo nanopositioner, demonstrating an experimental open-loop crossover increase of approximately 55~Hz and a closed-loop bandwidth improvement of about 34~Hz relative to a well-tuned linear baseline.