FIASCO

Fixed Integrated Approach to Synthesize COntrollers

$H_{\infty}$ and $\mu$-synthesis techniques have become generally accepted methods in modern robust control design. They permit multivariable controller synthesis while accounting for multiple uncertainty sources in the system. However, a significant shortcoming of these techniques is the fact that they generally lead to high order controllers. Model order reduction techniques employed to decrease controller complexity do not guarantee robustness properties. This illustrates the need for robust control design where the order of the controller is constrained a priori in the design process. $\mu$-synthesis alleviates the conservatism introduced by $H_{\infty}$ controllers when multiple uncertainty sources are present in the system. However, $\mu$-synthesis is still conservative in that only complex representations of uncertainty models are considered. In the case of real parameter uncertainty, this representation can be arbitrarily conservative. A technique has been developed to synthesize fixed order mu-controllers with robustness to mixed real/complex uncertainties. A homotopy algorithm is used to design $H_{\infty}$ compensators of constrained dimension. This technique is incorporated into a mixed real/complex $\mu$-synthesis procedure resulting in controllers which decrease conservatism and reduce controller complexity. The capabilities of the new technique are demonstrated on a simplified mixed mu design problem and a helicopter example. A robust control study for a hypersonic vehicle further illustrates the feasibility of the developed method.

Also included is a collection of MATLAB files called the FIASCO-Toolbox.

FIASCO Toolbox fiasco.tar.gz

Publications

Journal Articles

  1. $\mu$\ Controllers: Mixed and FixedHarald Buschek, Anthony J. CaliseJournal of Guidance Control and Dynamics, 20(1):34-41, January, 1997buschek:jgcd:1997Keywords: robust controlFiles: File 1
  2. Uncertainty Modeling and Fixed-Order Controller Design for a Hypersonic Vehicle Model Harald Buschek, Anthony J. CaliseJournal of Guidance Control and Dynamics, 20(1):115-122, January, 1997buschek:jgcd:1997bKeywords: hypersonic, mu controllers

Conference Papers

  1. Hypersonic Flight Control Design Using Fixed Order Robust ControllersHarald Buschek, Anthony J. CaliseSixth International Aerospace Planes and Hypersonics Technologies Conference, Chattanooga, TN, April, 1995buschek:aphc:1995Keywords: robust controlFiles: File 1, File 2
  2. $\mu$\ Controllers: Mixed and FixedHarald Buschek, Anthony J. CaliseAIAA Guidance Navigation and Control Conference, Baltimore, MD, August, 1995buschek:gnc:1995Keywords: mu controllersFiles: File 1, File 2
  3. Fixed Order Robust Control Design for Hypersonic VehiclesHarald Buschek, Anthony J. CaliseAIAA Guidance Navigation and Control Conference, Scottsdale, AZ, August, 1994buschek:gnc:1994Keywords: hypersonic, robust control
  4. Robust control of hypersonic vehicles considering propulsive and aeroelastic effects Harald Buschek, Anthony J. CaliseAIAA Guidance Navigation and Control Conference, Monterey, CA, August, 1993buschek:gnc:1993Keywords: hypersonic, robust control

Theses

  1. Synthesis of Fixed Order Controllers with Robustness to Mixed Real/Complex UncertaintiesHarald BuschekGeorgia Institute of Technology, 270 Ferst Drive, Atlanta GA 30332, U.S.A., 1995buschek:phdKeywords: hypersonic, robust control