An Improved Active Disturbance Rejection Control for Bode's Ideal Transfer Function

TL;DR

This paper introduces an improved active disturbance rejection control scheme with a fractional-order observer, enhancing robustness and performance for high-order systems and real-world applications like PMSM servo control.

Contribution

The paper develops an improved fractional-order ESO within ADRC, reducing system states to estimate and outperforming previous fractional and integer-order ADRC methods.

Findings

Better estimation performance than fractional-order ESO

Enhanced transient response and robustness in simulations

Successful application to PMSM servo control system

Abstract

This paper presents an active disturbance rejection control (ADRC) scheme with an improved fractional-order extended state observer (IFO-ESO).Based on the new ADRC scheme, the open-loop transfer function of a high-order system can be approximately rendered to a so-called Weighed Bode's ideal transfer function, whose closed-loop performance is less prone to the controller parameter variations. The design of the IFO-ESO helps reduce the number of system states to be estimated and improves the performance of closed-loop system over %the previously proposed the fractional-order active disturbance rejection control (FO-ADRC) in the literature. Compared with the integer-order active disturbance rejection controller (IO-ADRC) and FO-ADRC, the auxiliary tracking controller of IFO-ADRC has a simpler form. Frequency-domain analysis shows that IFO-ESO has better estimation performance than fractional-order ESO, and time-domain simulation demonstrates that the proposed ADRC has better transient performance and is more robust against the parameter variations than FO-ADRC and IO-ADRC. The proposed ADRC is applied to permanent magnet synchronous motor (PMSM) servo control system and demonstrates its capability in a real-world application.