Development of Robust Fractional-Order Reset Control

TL;DR

This paper introduces a new control framework combining fractional-order CRONE control with non-linear reset techniques, enhancing tuning flexibility and phase margin, validated through precision positioning experiments.

Contribution

It develops a novel CRONE reset control design framework, integrating fractional-order tuning with reset control to improve performance and industry compatibility.

Findings

CRONE reset control improves tracking performance over linear CRONE control.

The framework provides better open-loop tuning and phase margin.

Experimental validation confirms performance enhancements.

Abstract

In this paper, a framework for the combination of robust fractional order CRONE control with non-linear reset is given for both first and second generation CRONE control. General design rules are derived and presented for these CRONE reset controllers. Within this framework, fractional order control allows for better tuning of the open-loop responses on the one hand. On the other, reset control enables a reduction in phase lag and a corresponding increase in phase margin compared to linear control for similar open loop gain profile. Hence, the combination of the two control methods can provide well-tuned open-loop responses that can overcome the fundamental linear control limitation of Bode's gain-phase relationship. Moreover, as established loop-shaping concepts are used in the controller design, CRONE reset can be highly compatible with the industry. The designed CRONE reset controllers are validated on a one degree-of-freedom Lorentz-actuated precision positioning stage. On this setup, CRONE reset control is shown to provide better tracking performance compared to linear CRONE control, which is in agreement with the predicted performance improvement.