Wyniki wyszukiwania - BazTech

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Towards a health-aware fault tolerant control of complex systems: A vehicle fleet case

Lipiec Bogdan, Mrugalski Marcin, Witczak Marcin, Stetter Ralf

International Journal of Applied Mathematics and Computer Science

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2022

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Vol. 32, no. 4

619--634

EN

The paper deals with the problem of health-aware fault-tolerant control of a vehicle fleet. In particular, the development process starts with providing the description of the process along with a suitable Internet-of-Things platform, which enables appropriate communication within the vehicle fleet. It also indicates the transportation tasks to the designated drivers and makes it possible to measure their realization times. The second stage pertains to the description of the analytical model of the transportation system, which is obtained with the max-plus algebra. Since the vehicle fleet is composed of heavy duty machines, it is crucial to monitor and analyze the degradation of their selected mechanical components. In particular, the components considered are ball bearings, which are employed in almost every mechanical transportation system. Thus, a fuzzy logic Takagi–Sugeno approach capable of assessing their time-to-failure is proposed. This information is utilized in the last stage, which boils down to health-aware and fault-tolerant control of the vehicle fleet. In particular, it aims at balancing the exploitation of the vehicles in such a way as to maximize they average time-to-failure. Moreover, the fault-tolerance is attained by balancing the use of particular vehicles in such a way as to minimize the effect of possible transportation delays within the system. Finally, the effectiveness of the proposed approach is validated using selected simulation scenarios involving vehicle-based transportation tasks.

2

Improving metrological properties of electric traction energy meters using fuzzy controllers

Dominikowski B., Pacholski D., Anuszczyk J., Gocek A.

Transport Problems

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2018

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T. 13, z. 1

147--158

EN

This paper presents the possibility of using a fuzzy controller to correct metrological properties of an electric traction energy meter. So far, no algorithms based on fuzzy logic to determine the desired conversion value of the current channel of the electricity meter have been applied. Currently, for the mentioned channel, conventional methods of gain determination are used, based on a sequential algorithm that controls operation of the programmable gain amplifier. The proposed corrector is designed for smart and continuous modification of the conversion factor of the low-voltage input part of the current channel in the electric energy meter. The authors have performed an accurate analysis of the current function in the main circuit of an electric locomotive by creating a model of a traction inverter subject to asynchronous motor load. An essential concept is this paper is to present the possibility of having a multi-input fuzzy controller split into two-input controllers connected in parallel and cascade. By performing a computer simulation of systems used for correcting metrological properties of electric traction energy meters, it has been proven that the applied fuzzy systems, based on an expert’s knowledge of digitally controlled PGA (Programmable Gain Amplifier) type operational amplifiers, are advantageous.

3

Block-structured models composed of nonlinear fuzzy dynamic and static parts : a case study

Bazydło P., Marusak P.

Journal of Automation Mobile Robotics and Intelligent Systems

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2018

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Vol. 12, No. 1

50--60

EN

The paper addresses issues of the dynamic fuzzy Takagi- Sugeno models identification for multi-step ahead prediction. In the case of highly nonlinear models, standard Takagi-Sugeno models may be hard to identify if they should be designed for recurrent prediction generation. In such a case, alternative fuzzy block-structured models composed of fuzzy dynamic and fuzzy static parts may be useful. Two main benefits of the proposed models are: (1) possibility to speed-up model tuning procedure, (2) potential to fine-tune an already available, standard Takagi-Sugeno model. The benefits offered by the proposed models are illustrated using the example of identification of a nonlinear process – a system consisting of two tanks of different shapes (cylindrical and conical ones).

4

An adaptive observer design approach for a class of discrete-time nonlinear systems

Srinivasarengan K., Ragot J., Aubrun C., Maquin D.

International Journal of Applied Mathematics and Computer Science

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2018

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Vol. 28, no. 1

55--67

EN

We consider the problem of joint estimation of states and some constant parameters for a class of nonlinear discrete-time systems. This class contains systems that could be transformed into a quasi-LPV (linear parameter varying) polytopic model in the Takagi–Sugeno (T–S) form. Such systems could have unmeasured premise variables, a case usually overlooked in the observer design literature. We assert that, for such systems in discrete-time, the current literature lacks design strategies for joint state and parameter estimation. To this end, we adapt the existing literature on continuous-time linear systems for joint state and time-varying parameter estimation. We first develop the discrete-time version of this result for linear systems. A Lyapunov approach is used to illustrate stability, and bounds for the estimation error are obtained via the bounded real lemma. We use this result to achieve our objective for a design procedure for a class of nonlinear systems with constant parameters. This results in less conservative conditions and a simplified design procedure. A basic waste water treatment plant simulation example is discussed to illustrate the design procedure.

5

New fault tolerant control strategies for nonlinear Takagi-Sugeno systems

Ichalal D., Marx B., Ragot J., Maquin D.

International Journal of Applied Mathematics and Computer Science

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2012

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Vol. 22, no. 1

197-210

EN

New methodologies for Fault Tolerant Control (FTC) are proposed in order to compensate actuator faults in nonlinear systems. These approaches are based on the representation of the nonlinear system by a Takagi-Sugeno model. Two control laws are proposed requiring simultaneous estimation of the system states and of the occurring actuator faults. The first approach concerns the stabilization problem in the presence of actuator faults. In the second, the system state is forced to track a reference trajectory even in faulty situation. The control performance depends on the estimation quality; indeed, it is important to accurately and rapidly estimate the states and the faults. This task is then performed with an Adaptive Fast State and Fault Observer (AFSFO) for the first case, and a Proportional-Integral Observer (PIO) in the second. Stability conditions are established with Lyapunov theory and expressed in a Linear Matrix Inequality (LMI) formulation to ease the design of FTC. Furthermore, relaxed stability conditions are given with the use of Polya's theorem. Some simulation examples are given in order to illustrate the proposed approaches.