scholarly journals Stability of fractional positive nonlinear systems

2015 ◽  
Vol 25 (4) ◽  
pp. 491-496 ◽  
Author(s):  
Tadeusz Kaczorek

AbstractThe conditions for positivity and stability of a class of fractional nonlinear continuous-time systems are established. It is assumed that the nonlinear vector function is continuous, satisfies the Lipschitz condition and the linear part is described by a Metzler matrix. The stability conditions are established by the use of an extension of the Lyapunov method to fractional positive nonlinear systems.

Mathematics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 202 ◽  
Author(s):  
Angelo Alessandri

Lyapunov functions enable analyzing the stability of dynamic systems described by ordinary differential equations without finding the solution of such equations. For nonlinear systems, devising a Lyapunov function is not an easy task to solve in general. In this paper, we present an approach to the construction of Lyapunov funtions to prove stability in estimation problems. To this end, we motivate the adoption of input-to-state stability (ISS) to deal with the estimation error involved by state observers in performing state estimation for nonlinear continuous-time systems. Such stability properties are ensured by means of ISS Lyapunov functions that satisfy Hamilton–Jacobi inequalities. Based on this general framework, we focus on observers for polynomial nonlinear systems and the sum-of-squares paradigm to find such Lyapunov functions.


Author(s):  
Wojciech Mitkowski

In applications we meet with positive (nonnegative) systems. A system generated by a linear differential equation with a Metzler-matrix is called a nonnegative system. The paper shows the basic dynamic properties of nonnegative continuous-time systems. Considered was the example of an oscillating electrical circuit with a cyclic Metzler-matrix, enabling the correct physical interpretations. Cykliczne obwody elektryczne Metzlera Streszczenie: Układy dodatnie (nieujemne) można spotkać w wielu zastosowaniach. Układem nieujemnym jest układ generowany równaniem różniczkowym liniowym z macierzą Metzlera. W artykule przedstawiono podstawowe własności dynamiczne układów nieujemnych z czasem ciągłym. Rozważono przykład elektrycznego obwodu oscylacyjnego z cykliczną macierzą Metzlera umożliwiający odpowiednie interpretacje fizyczne. Słowa kluczowe: układy dodatnie, układy Metzlera, układy cykliczne, obwody elektryczne


2011 ◽  
Vol 21 (2) ◽  
pp. 167-188 ◽  
Author(s):  
Tadeusz Kaczorek

Positive stable realizations with system Metzler matricesConditions for the existence of positive stable realizations with system Metzler matrices for linear continuous-time systems are established. A procedure for finding a positive stable realization with system Metzler matrix based on similarity transformation of proper transfer matrices is proposed and demonstrated on numerical examples. It is shown that if the poles of stable transfer matrix are real then the classical Gilbert method can be used to find the positive stable realization.


Author(s):  
Tadeusz Kaczorek

AbstractThe positivity and stability of standard and fractional descriptor continuous-time linear and nonlinear systems are addressed. Necessary and sufficient conditions for the positivity of descriptor linear and sufficient conditions for nonlinear systems are established. Using an extension of Lyapunov method sufficient conditions for the stability of positive nonlinear systems are given. The considerations are extended to fractional nonlinear systems.


2015 ◽  
Vol 25 (4) ◽  
pp. 827-831 ◽  
Author(s):  
Tadeusz Kaczorek

Abstract The positivity and linearization of a class of nonlinear continuous-time system by nonlinear state feedbacks are addressed. Necessary and sufficient conditions for the positivity of the class of nonlinear systems are established. A method for linearization of nonlinear systems by nonlinear state feedbacks is presented. It is shown that by a suitable choice of the state feedback it is possible to obtain an asymptotically stable and controllable linear system, and if the closed-loop system is positive then it is unstable.


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