Discrete FIR filter-based Control.

In control system design, managing measurement noise is a critical challenge, requiring a balance between responsiveness and noise suppression. Traditional methods often involve trade-offs, compromising either aspect. This paper proposes a novel solution by integrating a Finite Impulse Response (FIR) filter within the discrete controller transfer function, coupled with disturbance rejection through the Internal Model Principle (IMP).

Active disturbance rejection control based on a cascade estimator composed of reduced-order and full-order extended state observers.

This paper presents a pioneering cascade estimator, CRESO, which merges reduced-order and full-order extended state observers (ESO) in a novel manner. CRESO is designed to navigate the trade-off between robustness, estimation accuracy, and noise amplification inherent in active disturbance rejection control (ADRC) schemes. An analysis in the frequency domain substantiates CRESO's performance and robustness capabilities compared to those of single-level ESO and cascade ESO (CESO).

On the equivalence between Generalized Proportional Integral Observer and Disturbance Observer.

This paper presents the equivalence between generalized proportional integral observer (GPIO) and disturbance observer (DOB), which is applicable to reduced-order GPIO (ROGPIO), full-order GPIO (FOGPIO), and extended state observer (ESO). From this equivalence, established in frequency-domain, comprehensive analyses are performed regarding the influence of the system order, the number of extended states, the uncertain control gain, and the tuning method on the robustness and performance of GPIO. In addition, the equivalence allows a detailed comparison between ROGPIO and FOGPIO in the active disturbance rejection control (ADRC) framework.

Robust fractional Active Disturbance Rejection Control: A unified approach.

This paper presents an adaptation of the Active Disturbance Rejection Control (ADRC) method within the fractional calculus context. This ADRC version is characterized by a single active cancellation of the lumped effects of all the unmodeled dynamics, external disturbances and parameter uncertainty associated with the linear model of commensurate fractional order. This methodology proposes suitable simplifications to fit the resulting system to one of appropriate commensurate fractional order.

Generalized proportional integral control for periodic signals under active disturbance rejection approach.

Conventional repetitive control has proven to be an effective strategy to reject/track periodic signals with constant frequency; however, it shows poor performance in varying frequency applications. This paper proposes an active disturbance rejection methodology applied to a large class of uncertain flat systems for the tracking and rejection of periodic signals, in which the possibilities of the generalized proportional integral (GPI) observer-based control to address repetitive control problems are studied. In the proposed scheme, model uncertainties and external disturbances are lumped together in a general additive disturbance input that is estimated and rejected on-line.