Title: A two-phase approach for the design of two-degree-of-freedom of robust controller for higher order interval system

Authors: D. Srinivasa Rao; Mangipudi Siva Kumar; M. Ramalinga Raju

Addresses: Department of Electrical and Electronics Engineering, Gudlavalleru Engineering College, Gudlavalleru, AP, India ' Department of Electrical and Electronics Engineering, Gudlavalleru Engineering College, Gudlavalleru, AP, India ' Department of Electrical and Electronics Engineering, University College of Engineering, JNT University of Kakinada, Kakinada, AP, India

Abstract: This paper proposes a novel method for the design of the robust controller to retain both the robust stability and performance of the higher order interval system via reduced order model using the differential evolution (DE) algorithm. A stable reduced interval model is generated from a higher order interval system using DE in order to minimise the cost and reduce the complexity of the system. The reduced order interval numerator and denominator polynomials are determined by minimising the integral squared error (ISE) using the DE. From the reduced order interval model, a robust PI controller is designed based on the new stability conditions of interval system. The designed robust controller from the reduced order interval model will be attributed to the higher order interval system. The designed PI controller from the proposed method not only stabilises the reduced order model, but also stabilises the original higher order system. Finally, with the help of frequency domain method a pre-filter is constructed to improve the performance of interval system. The viability of the proposed methodology is illustrated through a numerical example for its successful implementation.

Keywords: interval system; Kharitonov's theorem; robust controller; model order reduction; differential evolution algorithm.

DOI: 10.1504/IJAAC.2020.105517

International Journal of Automation and Control, 2020 Vol.14 No.2, pp.161 - 186

Received: 09 Feb 2018
Accepted: 09 Jul 2018
Published online: 03 Mar 2020 *

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