Non-Minimum-Phase Resonant Controller for Active Damping Control: Application to Piezo-Actuated Nanopositioning System

TL;DR

This paper introduces a novel non-minimum-phase resonant controller for active damping in nanopositioning systems, achieving high bandwidth and robustness against resonance variations through a combined control strategy validated by experiments.

Contribution

The paper proposes a new NRC design that effectively damps resonances and enhances bandwidth in nanopositioning systems, with a tunable phase approach and experimental validation.

Findings

Achieved dual closed-loop bandwidths of 895 Hz and 845 Hz.

Successfully damped multiple flexural modes.

Surpassed the primary resonance frequency in experimental tests.

Abstract

Nanopositioning systems frequently encounter limitations in control bandwidth due to their lightly damped resonance behavior. This paper presents a novel Non-Minimum-Phase Resonant Controller (NRC) aimed at active damping control within dual closed-loop architectures, specifically applied to piezo-actuated nanopositioning systems. The control strategy is structured around formulated objectives for shaping sensitivity functions to meet predetermined system performance criteria. Leveraging non-minimum-phase characteristics, the proposed NRC accomplishes complete damping and the bifurcation of double resonant poles at the primary resonance peak through a constant-gain design accompanied by tunable phase variation. The NRC demonstrates robustness against frequency variations of the resonance arising from load changes and is also capable of damping higher-order flexural modes simultaneously. Furthermore, by establishing high gains at low frequencies within the inner closed-loop and integrating it with a conventional PI tracking controller, the NRC achieves substantial dual closed-loop bandwidths that can exceed the first resonance frequency. Moreover, the NRC significantly diminishes the effect of low-frequency reference signals on real feedback errors while effectively rejecting disturbances proximate to the resonance frequency. All contributions are thoroughly formulated and exemplified mathematically, with the controller's performance confirmed through an experimental setup utilizing an industrial nanopositioning system. The experimental results indicate dual closed-loop bandwidths of 895 Hz and 845 Hz, characterized by $\pm$3 dB and $\pm$1 dB bounds, respectively, that surpass the resonance frequency of 739 Hz.