Robust Stability Analysis of “Unstructured” Convex Combinations of Matrices With Applications

Author(s):  
Rama K. Yedavalli

This paper presents new insight into the robust stability analysis of families of matrices described by convex combinations of Hurwitz stable 'vertex' matrices. Significant new insight is provided that removes many misconceptions that currently prevail in this problem formulation. In this connection, careful distinction is made between 'Structured' and 'Unstructured' convex combinations of matrices. The convex combinations arising from an uncertain matrix with interval parameters is labeled as 'structured' convex combinations whereas the convex combinations of 'user specified' Hurwitz stable vertex matrices are labeled as 'unstructured' convex combinations. It is clearly shown that the convex combination property in matrix case is dictated more by the nature of the 'vertex' matrices rather than by simply assigning values to the coefficients of the combination. From this analysis, it is clearly established that 'structured' and 'unstructured' convex combinations are two entirely different problem formulations and one is not a special case of the other as it is currently believed. Thus even the solution algorithms for checking the stability of these matrix families are different. After establishing this distinction, this paper then concentrates on the 'unstructured' case and provides a 'vertex solution' to a specific three vertex convex combination problem. The algorithm is illustrated with several examples. This contribution suggests that there is still considerable research needed to appreciably enhance the knowledge base in the important area of robust stability analysis of matrix families which arise in various applications.

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Yanwen Liu ◽  
Fanwei Meng ◽  
Bowen Guan ◽  
Shuhao Zhang

This paper presents the robust stability analysis based on LMI for force feedback haptic interface systems with uncertain delay. A full-order state observer is introduced to estimate states of the haptic device so as to directly obtain the feedback force, which expands the stability range of the system environment parameters when comparing with that of the system without an observer. By using the delay partitioning idea and the augmented state vector, the Lyapunov-Krasovskii functional is constructed, and then the new stability criterion based on LMI is given in the paper. With this new stability criterion, the observer gains can also be obtained directly. At last, a concrete example is used to prove the effectiveness and less conservativeness of this new approach.


2010 ◽  
Vol 2010 ◽  
pp. 1-24 ◽  
Author(s):  
Mohamed Moez Belhaouane ◽  
Mohamed Faiez Ghariani ◽  
Hela Belkhiria Ayadi ◽  
Naceur Benhadj Braiek

This paper deals with the problems of robust stability analysis and robust stabilization for uncertain nonlinear polynomial systems. The combination of a polynomial system stability criterion with an improved robustness measure of uncertain linear systems has allowed the formulation of a new criterion for robustness bound estimation of the studied uncertain polynomial systems. Indeed, the formulated approach is extended to involve the global stabilization of nonlinear polynomial systems with maximization of the stability robustness bound. The proposed method is helpful to improve the existing techniques used in the analysis and control for uncertain polynomial systems. Simulation examples illustrate the potentials of the proposed approach.


Author(s):  
Mohammad Tavazoei ◽  
Mohammad Hassan Asemani

This paper focuses on the stability analysis of linear fractional-order systems with fractional-order 0<α<2, in the presence of time-varying uncertainty. To obtain a robust stability condition, we first derive a new upper bound for the norm of Mittag-Leffler function associated with the nominal fractional-order system matrix. Then, by finding an upper bound for the norm of the uncertain fractional-order system solution, a sufficient non-Lyapunov robust stability condition is proposed. Unlike the previous methods for robust stability analysis of uncertain fractional-order systems, the proposed stability condition is applicable to systems with time-varying uncertainty. Moreover, the proposed condition depends on the fractional-order of the system and the upper bound of the uncertainty matrix norm. Finally, the offered stability criteria are examined on numerical uncertain linear fractional-order systems with 0<α<1 and 1<α<2 to verify the applicability of the proposed condition. Furthermore, the stability of an uncertain fractional-order Sallen–Key filter is checked via the offered condition.


2021 ◽  
pp. 1-1
Author(s):  
Majid Ghorbani ◽  
Mahsan Tavakoli-Kakhki ◽  
Aleksei Tepljakov ◽  
Eduard Petlenkov ◽  
Arash Farnam ◽  
...  

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
H. Saberi Najafi ◽  
A. Refahi Sheikhani ◽  
A. Ansari

We analyze the stability of three classes of distributed order fractional differential equations (DOFDEs) with respect to the nonnegative density function. In this sense, we discover a robust stability condition for these systems based on characteristic function and new inertia concept of a matrix with respect to the density function. Moreover, we check the stability of a distributed order fractional WINDMI system to illustrate the validity of proposed procedure.


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