Wyniki wyszukiwania - BazTech

1

Fourth order computational spline method for two-parameter singularly perturbed boundary value problem

Kambampati Satyanarayana, Emineni Siva Prasad, Reddy M. Chenna Krishna, Kolloju Phaneendra

International Journal of Applied Mechanics and Engineering

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2023

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Vol. 28, no. 4

79--93

EN

The current research work considers a two-parameter singularly perturbed two-point boundary value problem. Here, we suggest a computational scheme derived by using an exponential spline for the numerical solution of the problem on a uniform mesh. The proposed numerical scheme is analyzed for convergence and an accuracy of O(h4) is achieved. Numerical experiments are considered to validate the efficiency of the spline method, and compared comparison with the existing method to prove the superiority of the proposed scheme.

2

A fault estimation and fault-tolerant control based sliding mode observer for LPV descriptor systems with time delay

Hamdi Habib, Rodrigues Mickael, Rabaoui Bouali, Benhadj Braiek Naceur

International Journal of Applied Mathematics and Computer Science

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2021

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Vol. 31, no. 2

247--258

EN

This paper considers the problem of fault-tolerant control (FTC) and fault reconstruction of actuator faults for linear parameter varying (LPV) descriptor systems with time delay. A polytopic sliding mode observer (PSMO) is synthesized to achieve simultaneous reconstruction of LPV polytopic descriptor system states and actuator faults. Exploiting the reconstructed actuator faults and state estimates, a fault-tolerant controller is designed to compensate the impact of actuator faults on system performance by stabilizing the closed-loop LPV delayed descriptor system. Besides, the controller and PSMO gains are obtained throughout the resolution of linear matrix inequalities (LMIs) using convex optimization techniques. The developed PSMO could force the output estimation error to converge to zero in a finite time when the actuators faults are bounded through the reinjection of the output estimation error via a nonlinear switching term. Simulation results applied to a given numerical system are presented to highlight the superiority and effectiveness of the proposed approach.

3

Fault tolerant multicontrollers for nonlinear systems: A real validation on a chemical process

Mejdi Sondess, Messaoud Anis, Ben Abdennour Ridha

International Journal of Applied Mathematics and Computer Science

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2020

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Vol. 30, no. 1

61--74

EN

An active sensor fault tolerant controller for nonlinear systems represented by a decoupled multimodel is proposed. Active fault tolerant control requires accurate fault estimation. Thus, to estimate both state variables and sensor faults, a discrete unknown input multiobserver, based on an augmented state multimodel, is designed. The multiobserver gains are computed by solving linear matrix inequalities with equality constraints. A multicontrol strategy is proposed for the compensation of the sensor fault and recovering the desired performances. This strategy integrates a bank of controllers, corresponding to a set of partial models, to generate a set of control laws compensating the fault effect. Then, a switching strategy between the generated local control laws is established in order to apply the most suitable control law that tolerates the fault and maintains good closed loop performances. The effectiveness of the proposed strategy is proven through a numerical example and also through a real time application on a chemical reactor. The obtained results confirm satisfactory closed loop performance in terms of trajectory tracking and fault tolerance.

4

Distributed fault estimation of multi-agent systems using a proportional-integral observer: A leader-following application

Farrera Beltrán, López-Estrada Francisco-Ronay, Chadli Mohammed, Valencia-Palomo Guillermo, Gómez-Peñate Samuel

International Journal of Applied Mathematics and Computer Science

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2020

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Vol. 30, no. 3

551--560

EN

This paper proposes a methodology for observer-based fault estimation of leader-following linear multi-agent systems subject to actuator faults. First, a proportional-integral distributed fault estimation observer is developed to estimate both actuator faults and states of each follower agent by considering directed and undirected graph topologies. Second, based on the proposed quadratic Lyapunov equation, sufficient conditions for the asymptotic convergence of the observer are obtained as a set of linear matrix inequalities. Finally, a numerical example is provided to illustrate the proposed approach.

5

Robust multiple sensor fault-tolerant control for dynamic non-linear systems: Application to the aerodynamical twin-rotor system

Pazera M., Buciakowski M., Witczak M.

International Journal of Applied Mathematics and Computer Science

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2018

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Vol. 28, no. 2

297--308

EN

The paper deals with the problem of designing sensor-fault tolerant control for a class of non-linear systems. The scheme is composed of a robust state and fault estimator as well as a controller. The estimator aims at recovering the real system state irrespective of sensor faults. Subsequently, the fault-free state is used for control purposes. Also, the robust sensor fault estimator is developed in a such a way that a level of disturbances attenuation can be reached pertaining to the fault estimation error. Fault-tolerant control is designed using similar criteria. Moreover, a separation principle is proposed, which makes it possible to design the fault estimator and control separately. The final part of the paper is devoted to the comprehensive experimental study related to the application of the proposed approach to a non-linear twin-rotor system, which clearly exhibits the performance of the new strategy.

6

Data-driven techniques for the fault diagnosis of a wind turbine benchmark

Simani S., Farsoni S., Castaldi P.

International Journal of Applied Mathematics and Computer Science

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2018

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Vol. 28, no. 2

247--268

EN

This paper deals with the fault diagnosis of wind turbines and investigates viable solutions to the problem of earlier fault detection and isolation. The design of the fault indicator, i.e., the fault estimate, involves data-driven approaches, as they can represent effective tools for coping with poor analytical knowledge of the system dynamics, together with noise and disturbances. In particular, the proposed data-driven solutions rely on fuzzy systems and neural networks that are used to describe the strongly nonlinear relationships between measurement and faults. The chosen architectures rely on nonlinear autoregressive models with exogenous input, as they can represent the dynamic evolution of the system along time. The developed fault diagnosis schemes are tested by means of a high-fidelity benchmark model that simulates the normal and the faulty behaviour of a wind turbine. The achieved performances are also compared with those of other model-based strategies from the related literature. Finally, a Monte-Carlo analysis validates the robustness and the reliability of the proposed solutions against typical parameter uncertainties and disturbances.

7

Systematic fault tolerant control based on adaptive Thau observer estimation for quadrotor UAVs

Cen Z., Noura H., Younes Y. A.

International Journal of Applied Mathematics and Computer Science

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2015

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Vol. 25, no. 1

159--174

EN

A systematic fault tolerant control (FTC) scheme based on fault estimation for a quadrotor actuator, which integrates normal control, active and passive FTC and fault parking is proposed in this paper. Firstly, an adaptive Thau observer (ATO) is presented to estimate the quadrotor rotor fault magnitudes, and then faults with different magnitudes and time-varying natures are rated into corresponding fault severity levels based on the pre-defined fault-tolerant boundaries. Secondly, a systematic FTC strategy which can coordinate various FTC methods is designed to compensate for failures depending on the fault types and severity levels. Unlike former stand-alone passive FTC or active FTC, our proposed FTC scheme can compensate for faults in a way of condition-based maintenance (CBM), and especially consider the fatal failures that traditional FTC techniques cannot accommodate to avoid the crashing of UAVs. Finally, various simulations are carried out to show the performance and effectiveness of the proposed method.

8

Robust sensor fault estimation for descriptor-LPV systems with unmeasurable gain scheduling functions: Application to an anaerobic bioreactor

López-Estrada F. R., Ponsart J. C., Theilliol D., Astorga-Zaragoza C. M., Camas-Anzueto J. L.

International Journal of Applied Mathematics and Computer Science

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2015

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Vol. 25, no. 2

233--244

EN

This paper addresses the design of a state estimation and sensor fault detection, isolation and fault estimation observer for descriptor-linear parameter varying (D-LPV) systems. In contrast to where the scheduling functions depend on some measurable time varying state, the proposed method considers the scheduling function depending on an unmeasurable state vector. In order to isolate, detect and estimate sensor faults, an augmented system is constructed by considering faults to be auxiliary state vectors. An unknown input LPV observer is designed to estimate simultaneously system states and faults. Sufficient conditions to guarantee stability and robustness against the uncertainty provided by the unmeasurable scheduling functions and the influence of disturbances are synthesized via a linear matrix inequality (LMI) formulation by considering H∞ and Lyapunov approaches. The performances of the proposed method are illustrated through the application to an anaerobic bioreactor model.

9

Application of the 3D objects surface shape analysis algorithms in biomedical engineering

Matan M.

Czasopismo Techniczne. Nauki Podstawowe

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2014

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R. 111, z. 2-NP

81--98

EN

The paper describes a concept of measuring possible error estimation and later the decomposition of the predefined model object into convex areas ECD (Exact Convex Decomposition) in order to find a solution to the problem of cavities location with the use of three-dimensional µ-tomography image of the tooth. Such an approach will enable the improvement of automatic cavities detection methods in the future. The paper is also concerned with the problem of a precise object acquisition and estimation of the error value during execution of automatic detection methods.

PL

Publikacja opisuje koncepcje pomiaru możliwego błędu wraz z dekompozycja predefiniowanego modelu obiektu do obszaru wypukłego z użyciem metod ECD (precyzyjnej dekompozycji wypukłej) w celu znalezienia rozwiązania problemu ubytków w zębach z wykorzystaniem trójwymiarowej tomografii obrazu zęba. Wykorzystanie tomografu i metod ECD pozwoli w przyszłości poprawić metody automatycznej detekcji ubytków. W publikacji również rozważany jest problem precyzyjnej akwizycji obiektu z szacowaniem błędu podczas wykonywania metod detekcji automatycznej.

10

The concept of the variance estimation for the neural network approximator by jackknife subsampling

Pietraszek J., Gądek-Moszczak A.

Czasopismo Techniczne. Mechanika

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2013

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R. 110, z. 1-M

309--316

EN

The estimation of a variance for a semi-parametric neural network model variance for geometric properties of sintered metal will be done on the basis of jackknife subsampling method. Calculation results are of great practical significance because it will be possible to use proposed approach in similar microscale modelling. The proposed approach is simple and has many advantages if model identification procedure is computational expensive.

PL

W artykule przedstawiono estymację wariancji półparametrycznego modelu neuronowego cech geometrycznych spieku metali przeprowadzoną za pomocą metody podpróbkowania jackknife. Obliczone wyniki są cenne z uwagi na możliwość zastosowania proponowanego podejścia do analogicznych zagadnień modelowania w mikroskali.