Robust H ∞  control via a stable decentralized nonlinear output feedback controller


  • Hendra G. Harno,

    1. Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, FL, USA
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    • Hendra G. Harno is currently affiliated with the Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, Durian Tunggal, 76100 Melaka, Malaysia. E-mail:
  • Ian R. Petersen

    Corresponding author
    1. School of Engineering and Information Technology, Australian Defence Force Academy, Canberra ACT, Australia
    • Correspondence to: Ian R. Petersen, School of Engineering and Information Technology, the University of New South Wales at the Australian Defence Force Academy (UNSW@ADFA), Northcott Drive, Canberra ACT 2600, Australia.


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This paper presents a new method to construct a decentralized nonlinear robust H ∞  controller for a class of large-scale nonlinear uncertain systems. The admissible uncertainties and nonlinearities in the system satisfy integral quadratic constraints and global Lipschitz conditions, respectively. The decentralized controller, which is required to be stable, is capable of exploiting known nonlinearities and interconnections between subsystems without treating them as uncertainties. Instead, additional uncertainties are introduced because of the discrepancies between nondecentralized and decentralized nonlinear output feedback controllers. The H ∞  control objective is to achieve an absolutely stable closed-loop system with a specified disturbance attenuation level. A solution to this control problem involves stabilizing solutions to algebraic Riccati equations parametrized by scaling constants corresponding to the uncertainties and nonlinearities. This formulation is nonconvex; hence, an evolutionary optimization method is applied to solve the control problem considered. Copyright © 2012 John Wiley & Sons, Ltd.