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A reliable algorithm for optimal control synthesisIn recent years, powerful design tools for linear time-invariant multivariable control systems have been developed based on direct parameter optimization. In this report, an algorithm for reliable optimal control synthesis using parameter optimization is presented. Specifically, a robust numerical algorithm is developed for the evaluation of the H(sup 2)-like cost functional and its gradients with respect to the controller design parameters. The method is specifically designed to handle defective degenerate systems and is based on the well-known Pade series approximation of the matrix exponential. Numerical test problems in control synthesis for simple mechanical systems and for a flexible structure with densely packed modes illustrate positively the reliability of this method when compared to a method based on diagonalization. Several types of cost functions have been considered: a cost function for robust control consisting of a linear combination of quadratic objectives for deterministic and random disturbances, and one representing an upper bound on the quadratic objective for worst case initial conditions. Finally, a framework for multivariable control synthesis has been developed combining the concept of closed-loop transfer recovery with numerical parameter optimization. The procedure enables designers to synthesize not only observer-based controllers but also controllers of arbitrary order and structure. Numerical design solutions rely heavily on the robust algorithm due to the high order of the synthesis model and the presence of near-overlapping modes. The design approach is successfully applied to the design of a high-bandwidth control system for a rotorcraft.
Document ID
19940018859
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Vansteenwyk, Brett (Washington Univ. Seattle, WA, United States)
Ly, Uy-Loi (Washington Univ. Seattle, WA, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1992
Subject Category
Cybernetics
Report/Patent Number
NASA-CR-194809
NAS 1.26:194809
Accession Number
94N23332
Funding Number(s)
CONTRACT_GRANT: NAG2-691
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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