Title: Robust cascade controller design for discrete minimum phase system using a novel data-driven virtual reference feedback tuning approach

Authors: Suresh Kumar Chiluka; Uday Bhaskar Babu Gara

Addresses: Department of EIE, CVR College of Engineering, Telangana, 501510, India ' Department of Chemical Engineering, National Institute of Technology Warangal, Telangana, 506004, India

Abstract: This work proposed a novel cascade controller design approach employing data-driven virtual reference feedback tuning (VRFT) to improve the performance and robustness. Selecting the closed-loop reference model [M(z)] is crucial in the conventional VRFT approach. Unlike the conventional VRFT method, the suggested approach has the distinctive property of using maximum sensitivity (M_s) as the design criterion for choosing the M(z), resulting in robust controllers. The proposed approach leads to improved closed-loop performance and stability. The proposed technique corroborates the standard series cascade (SSC) and modified series cascade (MSC) structures. Each structure's inner and outer loop controllers are designed by considering one and two reference models. Additionally, it clarifies the robustness and fragility with a perturbed plant and controller, respectively. The simulation results demonstrate enhanced robustness and overall performance attainment with the proposed approach.

Keywords: virtual reference feedback tuning; VRFT; robust control; series cascade; fragility; minimum phase system; maximum sensitivity.

DOI: 10.1504/IJAAC.2024.138245

International Journal of Automation and Control, 2024 Vol.18 No.3, pp.347 - 384

Received: 08 Mar 2023
Accepted: 17 Jun 2023
Published online: 30 Apr 2024 *

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