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Your search keyword '"Niculescu, Silviu-Iulian"' showing total 200 results
Start Over Author "Niculescu, Silviu-Iulian" Publication Type Periodicals Publisher ieee
200 results on '"Niculescu, Silviu-Iulian"'

21. Characterizing PID Controllers for Linear Time-Delay Systems: A Parameter-Space Approach.

Author

Li, Xu-Guang, Niculescu, Silviu-Iulian, Chen, Jun-Xiu, and Chai, Tianyou

Subjects
*LINEAR systems, *BEHAVIORAL assessment, *STABILITY criterion
Abstract

We focus on the proportional-integral-derivative (PID) controller design for linear time-delay systems. All the controller gains ($k_P$ , $k_I$ , and $k_D$) and the delay ($\tau$) are treated as free parameters and no particular constraints are imposed on the controlled plants. Such a problem (involving totally four free parameters) is of theoretical as well as practical importance, but, to the best of the authors’ knowledge, it has not been fully explored. First, we will develop an algebraic algorithm to solve the complete stability problem w.r.t. $\tau$. Consequently, for any given PID controller vector $(k_P, k_I, k_D)$ , the distribution of ${NU}(\tau)$ (${NU}(\tau)$ denotes the number of characteristic roots in the right-half plane, as a function of $\tau$) can be accurately obtained and the exhaustive stability range of $\tau$ may be automatically calculated. Next, a global understanding of the distribution of ${NU}(\tau)$ over the whole $(k_P, k_I, k_D)$ -space may be achieved and all structural changes regarding the ${NU}(\tau)$ distribution can be analytically determined. To achieve such a goal, a complete positive real root classification (for some appropriate auxiliary characteristic equation) will be explicitly proposed. Finally, we will give a new methodology, a new parameter-space approach, for determining the stability set in the $(k_P, k_I, k_D, \tau)$ -space. [ABSTRACT FROM AUTHOR]

Published
2021
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32. Stability and Stabilization Through Envelopes for Retarded and Neutral Time-Delay Systems.

Author

Cardeliquio, Caetano B., Fioravanti, Andre R., Bonnet, Catherine, and Niculescu, Silviu-Iulian

Subjects
LINEAR matrix inequalities, TIME delay systems, STATE feedback (Feedback control systems), SYMMETRIC matrices
Abstract

This paper deals with a new approach to develop an envelope that engulfs all poles of a time-delay system. Through linear matrix inequalities, we are able to determine envelopes for retarded and neutral time-delay systems. The envelopes proposed are not only tighter than the ones in the literature, but, with our procedure, they can also be applied to verify the stability of the system and design state-feedback controllers, which cope with design requirements regarding $\alpha$ -stability. [ABSTRACT FROM AUTHOR]

Published
2020
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40. Comparative Study and Application-Oriented Classification of Vehicular Map-Matching Methods.

Author

Kubicka, Matej, Cela, Arben, Mounier, Hugues, and Niculescu, Silviu-Iulian

Abstract

Vehicular map-matching aims to identify the position of a vehicle in a road-network. Different map-matching applications make use of different formulations of the problem leading to some ambiguous usage. This work intends to make a step towards resolution of this issue. We cross-link mapmatching methods, classes and applications in order to provide insight into this area of study. A selection of current map-matching methods is reviewed, classified and appropriately linked with other methods. Conclusions on trends and influential ideas are drawn with respect to the specific flavor of individual applications. Finally, the trade-offs that must be considered when selecting a map-matching method are discussed and selection guidelines are provided. [ABSTRACT FROM PUBLISHER]

Published
2018
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41. Time-Delay Algorithms for Damping Oscillations of Suspended Payload by Adjusting the Cable Length.

Author

Vyhlidal, Tomas, Anderle, Milan, Busek, Jaroslav, and Niculescu, Silviu-Iulian

Abstract

This paper deals with damping oscillations of a payload suspended to a fixed position base (e.g., a standing crane trolley). The damping is done by utilizing the Coriolis force generated by synchronizing translational and rotational motion of the payload. After revising existing approaches mainly based on approximating the payload motion by the motion of a mathematical pendulum, several nonlinear time-delay algorithms are proposed to handle the given task efficiently. The key benefit of the proposed methods is the feedback character of the algorithms guaranteeing the required synchronization of the cable length adjustment with the payload swing motion under the varying oscillation period and even under the effect of external disturbances. Note that the preceding algorithms were of open-loop character where such a synchronization was not guaranteed. The theoretical design is validated by simulations. The implementation aspects are discussed by relaxing the simplifying assumptions. Finally, the proposed time-delay feedback method is experimentally verified on a laboratory setup. The achieved results demonstrate viability of the proposed method for payload oscillation damping, e.g., in crane applications. [ABSTRACT FROM PUBLISHER]

Published
2017
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42. Stability Analysis of a More General Class of Systems With Delay-Dependent Coefficients.

Author

Jin, Chi, Gu, Keqin, Boussaada, Islam, and Niculescu, Silviu-Iulian

Subjects
COEFFICIENTS (Statistics), TIME delay systems, LYAPUNOV functions, NUMERICAL analysis, DIFFERENTIAL equations
Abstract

This paper presents a systematic method to analyze the stability of systems with single delay in which the coefficient polynomials of the characteristic equation depend on the delay. Such systems often arise in, for example, life science and engineering systems. A method to analyze such systems was presented by Beretta and Kuang in a 2002 paper, but with some very restrictive assumptions. This paper extends their results to the general case with the exception of some degenerate cases. It is found that a much richer behavior is possible when the restrictive assumptions are removed. The interval of interest for the delay is partitioned into subintervals so that the magnitude condition generates a fixed number of frequencies as functions of the delay within each subinterval. The crossing conditions are expressed in a general form, and a simplified derivation for the first-order derivative criterion is obtained. Illustrative examples are also presented in this paper. [ABSTRACT FROM AUTHOR]

Published
2019
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