Sara Ifqir

Bio: Sara Ifqir is an academic researcher from University of Évry Val d'Essonne. The author has contributed to research in topics: Observer (quantum physics) & Bounded function. The author has an hindex of 6, co-authored 15 publications receiving 75 citations.

Adaptive Threshold Generation for Vehicle Fault Detection Using Switched T–S Interval Observers

Abstract: This paper is concerned with the robust passive fault detection problem for switched continuous-time linear parameter-varying systems with mensurable and unmeasurable scheduling parameters. A switched Takagi–Sugeno (TS) interval observer is designed to estimate the set of admissible state values. Using multiple fuzzy input to state stability-Lyapunov function and average dwell time (ADT) concept, sufficient conditions to guarantee the convergence and the robustness of the proposed observer are obtained. These conditions are formulated as a linear matrix inequality (LMI) problem. In contrast to the existing results based on multiple Lyapunov function and ADT switching, the derived conditions lead to less conservative LMIs characterization. Subsequently, the residual intervals are generated using the designed interval observer and used directly for fault detection (FD) decision making. Finally, the proposed methodology is tested using two examples. First, an academic example is used to illustrate the obtained relaxation. Second, a nonlinear vehicle model corrupted by faults is considered. Longitudinal velocity and cornering stiffness coefficients are treated, respectively, as the measurable and unmeasurable scheduling parameters. Simulation results based on experimental data show the effectiveness of the proposed FD schema.

Synchronous interval observer design for switched LPV systems using multiple quadratic ISS-Lyapunov functions

Abstract: This paper deals with the problem of robust state estimation for switched LPV continuous-time systems with measurable and unmeasurable scheduling parameters. The switching law is assumed to be uncontrollable but online available, while the unmeasurable varying parameters are assumed to be bounded with a priori known bounds. The proposed approach is based on switched interval observers which provide guaranteed lower and upper bounds allowing to evaluate the set of admissible values of the real state vector. The stability and positivity conditions of the switched interval error are expressed in terms of linear matrix inequalities (LMIs), which have been established using multiple quadratic ISS-Lyapunov functions (MQLF) and average dwell-time concept. In order to enhance estimation accuracy and robustness an explicit bound of the interval error is guaranteed. The proposed approach is applied to robust estimation of vehicle lateral dynamics. Tests are conducted on experimental data in order to prove the effectiveness of the proposed switched interval observer.

Interval Observer-Based Controller Design for Systems with State Constraints: Application to Solid Oxide Fuel Cells Stacks

Abstract: For many practical applications, it is necessary to design controllers that are, one the one hand, robust against bounded uncertainty in selected parameters and external disturbances. On the other hand, it is also quite common for such systems, that state constraints need to be accounted for which must not be exceeded for any possible parameter value. Although the task is quite challenging, several robust control design procedures were designed in recent years which allow for solving these problems, especially with respect to the latter aspect. In this paper, such robust control procedures are combined in a novel manner with an interval observer to additionally handle the influence of unknown but bounded measurement noise and to prevent the violation of state constraints in a provable fashion.

Monotone Dynamical Systems: An Introduction To The Theory Of Competitive And Cooperative Systems (Mathematical Surveys And Monographs) By Hal L. Smith

Abstract: Monotone dynamical systems Stability and convergence Competitive and cooperative differential equations Irreducible cooperative systems Cooperative systems of delay differential equations Nonquasimonotone delay differential equations Quasimonotone systems of parabolic equations A competition model Appendix Bibliography.

Detection and Isolation of False Data Injection Attacks in Smart Grid via Unknown Input Interval Observer

Abstract: This article investigates the detection and isolation of false data injection (FDI) attacks in a smart grid based on the unknown input (UI) interval observer. Recent studies have shown that the FDI attacks can bypass the traditional bad data detection methods by using the vulnerability of state estimation. For this reason, the emergency of FDI attacks brings enormous risk to the security of smart grid. To solve this crucial problem, an UI interval observer-based detection and the isolation scheme against FDI attacks are proposed. We first design the UI interval observers to obtain interval state estimation accurately, based on the constructed physical dynamics grid model. Through the capabilities of the designed UI interval observers, the accurate interval estimation state can be decoupled from unknown disturbances. Based on the characteristics of the interval residuals, a UI interval observer-based global detection algorithm was proposed. Particularly, the interval residual-based detection criteria can address the limitation of the precomputed threshold in traditional bad data detection methods. On this basis, we further consider the detection and isolation of FDI attacks under structure vulnerability. Namely, there exist undetectable FDI attacks in the grid system. Taking the attack undetectability problem into account, a logic judgment matrix-based local detection and isolation algorithm against FDI attacks are developed. Based on the combinations of observable sensor cases, local control centers can further detect and isolate the attack set under structure vulnerability. Finally, the effectiveness of the developed detection and isolation algorithms against FDI attacks is demonstrated on the IEEE 8-bus and IEEE 118-bus smart grid system, respectively.

Stator-Winding Incipient Shorted-Turn Fault Detection for Motor System in Motorized Spindle Using Modified Interval Observers

Abstract: As an important part of the power source, the motorized spindle is considered as the components in the high-end computer numerical control (CNC) machine tools, which is required as special attention to avoid expensive production shutdown due to the appearance of massive failures. Therefore, it is necessary to detect the incipient fault of the motorized spindle by establishing an appropriate model. This article presents a scheme for detecting the stator-winding incipient shorted-turn fault of the motor system in the motorized spindle. As the cornerstone of the model-based fault detection scheme, the electromagnetic coupling motor model in the motorized spindle with the stator-winding incipient shorted-turn fault under $dq$ coordinate is given. In the presence of electromagnetic disturbance, two aspects can make the stator-winding shorted-turn fault of the motor in motorized spindle detected earlier. First, the modified interval observer based on the established mathematical model of the motor in the motorized spindle has more design freedom than the Luenberger interval observer, which can make the residual interval generated in the optimization process have better performance and a wider range of applications. Second, the $l_{1}/H_{\infty }$ performance is introduced in the process of residual interval generation, which can make it have better electromagnetic disturbance robustness and incipient fault sensitivity. The effectiveness of the proposed scheme is illustrated by numerical simulation and is further validated by lab experiments on a 9.8-kW motorized spindle test rig.