Stability margins for Hurwitz polynomialsThe authors treat the robust stability issue using the characteristic polynomial, for two different cases: first in coefficient space with respect to perturbations in the coefficient of the characteristic polynomial; and then for a control system containing perturbed parameters in the transfer function description of the plant. In coefficient space, a simple expression is first given for the l-(squared) stability margin for both the monic and nonmonic cases. Following this, a method is given to find the l(infinity) margin, and the method is extended to reveal much larger stability regions. In parameter space the authors consider all single-input (multi-output) or single-output (multi-input) systems with a fixed controller and a plant described by a set of transfer functions which are ratios of polynomials with variable coefficients. A procedure is presented to calculate the radius of the largest stability ball in the space of these variable parameters. The calculation serves as a stability margin for the control system. The formulas that result are quasi-closed-form expressions for the stability margin and are computationally efficient.
Document ID
19890041243
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Chapellat, Herve (Texas A&M Univ. College Station, TX, United States)
Bhattacharyya, S. P. (Texas A & M University College Station, United States)
Keel, L. H. (Tennessee State University Nashville, United States)