scholarly journals A lower bound for the stability radius of time-varying systems

2004 ◽  
Vol 132 (12) ◽  
pp. 3653-3659 ◽  
Author(s):  
Adina Luminiţa Sasu ◽  
Bogdan Sasu
Author(s):  
Fritz Colonius ◽  
Wolfgang Kliemann

Abstract The dynamics of many mechanical systems can be described, or approximated by smooth vector fields in d-dimensional space Rd. External and internal excitations as well as modeling uncertainties are incorporated in the vector fields as families of (time-varying) functions, possibly with their own dynamics. The problem then is to study the response behavior of the system under the given uncertainty structure. In this paper we analyze the stability of uncertain systems at an equilibrium point, using the concept of stability radii. Roughly, a stability radius is the smallest excitation range such that a (time-varying) perturbation within this range can render the system unstable. Since we consider time-varying perturbations, the precise stability radius of the system is determined by the maximal Lyapunov exponent of the linearization at the equilibrium point. Several examples illustrate the theory and compare the precise stability radius to the one obtained via Lyapunov function techniques.


1970 ◽  
Vol 18 (2) ◽  
pp. 267-281 ◽  
Author(s):  
James H. Taylor ◽  
Kumpati S. Narendra

Author(s):  
Sunhua Huang ◽  
Runfan Zhang ◽  
Diyi Chen

This paper is concerned with the stability of nonlinear fractional-order time varying systems with Caputo derivative. By using Laplace transform, Mittag-Leffler function, and the Gronwall inequality, the sufficient condition that ensures local stability of fractional-order systems with fractional order α : 0<α≤1 and 1<α<2 is proposed, respectively. Moreover, the condition of the stability of fractional-order systems with a state-feedback controller is been put forward. Finally, a numerical example is presented to show the validity and feasibility of the proposed method.


2019 ◽  
Vol 12 (06) ◽  
pp. 1950066
Author(s):  
Boulbaba Ghanmi

This paper investigates the stability analysis with respect to part of the variables of nonlinear time-varying systems with impulse effect. The approach presented is based on the specially introduced piecewise continuous Lyapunov functions. The Lyapunov stability theorems with respect to part of the variables are generalized in the sense that the time derivatives of the Lyapunov functions are allowed to be indefinite. With the help of the notion of stable functions, asymptotic partial stability, exponential partial stability, input-to-state partial stability (ISPS) and integral input-to-state partial stability (iISPS) are considered. Three numerical examples are provided to illustrate the effectiveness of the proposed theoretical results.


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