Search for: fault-tolerant-control
Total 32 records
A unified framework for passive–active fault-tolerant control systems considering actuator saturation and L∞ disturbances, Article International Journal of Control ; 2017 , Pages 1-11 ; 00207179 (ISSN) ; Haeri, M ; Sharif University of Technology
This paper presents a unified passive–active fault-tolerant control strategy to compensate the loss of actuators’ effectiveness. The proposed approach is capable of handling the system in pre- and post-fault diagnosis intervals by passive and active approaches, respectively. The stability of the designed system is independent of the accuracy of information provided by the fault detection and diagnosis unit, however, a precise estimation could improve the conservation. Actuator saturation and L∞ disturbances effects are considered in the design stage. The trade-off between maximising the domain of attraction and minimising the effects of L∞ disturbances is tackled by developing a non-constant...
A unified framework for passive–active fault-tolerant control systems considering actuator saturation and L ∞ disturbances, Article International Journal of Control ; Volume 92, Issue 3 , 2019 , Pages 653-663 ; 00207179 (ISSN) ; Haeri, M ; Sharif University of Technology
Taylor and Francis Ltd 2019
This paper presents a unified passive–active fault-tolerant control strategy to compensate the loss of actuators’ effectiveness. The proposed approach is capable of handling the system in pre- and post-fault diagnosis intervals by passive and active approaches, respectively. The stability of the designed system is independent of the accuracy of information provided by the fault detection and diagnosis unit, however, a precise estimation could improve the conservation. Actuator saturation and L ∞ disturbances effects are considered in the design stage. The trade-off between maximising the domain of attraction and minimising the effects of L ∞ disturbances is tackled by developing a...
Fault-Tolerant control of uncertain linear systems in the presence of L∞ disturbances and actuator saturation, Article 4th International Conference on Control, Instrumentation, and Automation, 27 January 2016 through 28 January 2016 ; 2016 , Pages 307-312 ; 9781467387040 (ISBN) ; Haeri, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
In this paper the fault-Tolerant control problem for uncertain linear systems in the presence of L, disturbances and actuator saturation is studied. The conflict between enlarging the domain of attraction and attenuating the effect of L, disturbances is tackled by proposing a non-constant state feedback controller. The feedback gains are calculated off-line by using linear matrix inequalities. In addition, the proposed method is capable of tolerating time-varying faults. The suggested approach is implemented on a sample model and the result is compared with other works
Fault-tolerant control considering time-varying bounds on faults, Article Transactions of the Institute of Measurement and Control ; Volume 40, Issue 10 , 2018 , Pages 2982-2990 ; 01423312 (ISSN) ; Haeri, M ; Sharif University of Technology
SAGE Publications Ltd 2018
This paper presents a novel fault-tolerant control strategy to compensate the time-varying loss of actuators’ effectiveness. It considers intermediate situations where the fault is not determined precisely (unlike active approaches) but overall estimations about its rate and final value are available through the previous experiences and/or experiments. Based on the estimations, two upper and lower time-varying bounds on the actuators’ effectiveness are established to be exploited in the procedure of controller design. In a special case, where these bounds are constant, the method will be reduced to the conventional passive approach. Also, actuator saturation and the effects of (Formula...
Fault-tolerant control of flexible satellite with magnetic actuation and reaction wheel, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; 2021 ; 09544100 (ISSN) ; Assadian, N ; Sharif University of Technology
SAGE Publications Ltd 2021
The attitude fault-tolerant control of a flexible satellite actuated by reaction wheels and magnetic torquer bars is investigated in this article. A low earth orbit is considered for moment perturbations such as drag and gravity gradient. Furthermore, the flexible panels attached to a rigid central body are modeled through the assumed mode approach by a finite set of bending modal motion. The ordinary differential equations of their generalized coordinates are found using Lagrange’s equation, and the resulting dynamical model is validated by comparing its simulation results to the NX Siemens software results. Finally, a fault-tolerant controller based on sliding mode control is suggested and...
Fault Tolerant Control Considering Actuator Saturation and External Disturbances, Ph.D. Dissertation Sharif University of Technology ; Haeri, Mohammad
A control system capable of tolerating system malfunctions while maintaining an acceptable level of performance is referred as fault tolerant control system. The constraints on the amplitude of input control signals limit the domain of attraction even for linear models. Ignoring this fact may lead to an unsatisfactory performance and even closed loop instability. Designing the controller such that the domain of attraction is maximized has been an attractive topic for researchers. On the other hand, persistent disturbances always play an essential role in the real word systems. Designing the controller in a way such that the effect of such disturbances is attenuated is another challenging...
Fault-tolerant Attitude Control of Sattelite Using Neural Networks, M.Sc. Thesis Sharif University of Technology ; Asadian, Nima
This research aims to introduce a new integrated fault tolerant attitude control system of satellites based on the neural networks. First, a linear controller and an optimal controller are designed assuming that no fault occurs in the reaction wheels of the satellite. It is obvious that these controllers are not able to respond properly when a fault occurs. Therefore, artificial neural networks are employed in the fault tolerant controller design. Neural networks are well-known for their adaptiveness and the ability to learn the dynamics of a system. Therefore, they can be used to predict the faulty conditions. In this research two approaches are examined to deal with the faulty conditions....
Fault Tolerant Control of Flexible Launch Vehicle Using Fractional-Order Controller, M.Sc. Thesis Sharif University of Technology ; Fathi Jegarkandi, Mohsen
In this research the attitude control of a flexible launch vehicle using fractional order proportional-integral-derivative controller in the presence of actuators failures is described. Other work done in this study is the investigation of on-line fault detection and diagnosis effects in the attitude control of flexible launch vehicle in the presence of actuator failures. Rigid-elastic equations of motion and assumed modes have been used to simulate dynamics of launch vehicle in the Simulink environment of MATLAB software using two elastic bending modes. The performance of fractional order controller has been compared with conventional proportional-integral-derivative and adaptive augmented...
Design of a fault tolerated intelligent cntrol system for a nuclear reactor power control: Using extended Kalman filter, Article Journal of Process Control ; Vol. 24, issue. 7 , 2014 , pp. 1076-1084 ; ISSN: 09591524 ; Salarieh, H ; Vosoughi, N ; Sharif University of Technology
In this paper an approach based on system identification is used for fault detection in a nuclear reactor. A continuous-time Extended Kalman Filter (EKF) is presented, which allows the parameters of the nonlinear system to be estimated. Also a fault tolerant control system is designed for the nuclear reactor during power changes operation. The proposed controller is an adaptive critic-based neuro-fuzzy controller. Performance of the controller in terms of transient response and robustness against failures is very good and considerable
Adaptive integrated guidance and fault tolerant control using backstepping and sliding mode, Article International Journal of Aerospace Engineering ; Volume 2015 , September , 2015 ; 16875966 (ISSN) ; Ashrafifar, A ; Mohsenipour, R ; Sharif University of Technology
Hindawi Publishing Corporation 2015
A new method of integrated guidance and control for homing missiles with actuator fault against manoeuvring targets is proposed. Model of the integrated guidance and control system in the pitch plane with actuator fault and some uncertainty is developed. A control law using combination of adaptive backstepping and sliding mode approaches is designed to achieve interception in the presence of bounded uncertainties and actuator fault. Simulation results show that new approach has better performance than adaptive backstepping and has good performance in the presence of actuator fault
Comparing the performance of reference trajectory management and controller reconfiguration in attitude fault tolerant control, Article 2017 Asia Conference on Mechanical and Aerospace Engineering, ACMAE 2017, 29 December 2017 through 31 December 2017 ; Volume 151 , 2018 ; 2261236X (ISSN) ; Alikhani, A ; Jegarkandi, M. F ; Sharif University of Technology
EDP Sciences 2018
Reference trajectory management is a method to modify reference trajectories for the faulty system. The modified reference trajectories define new maneuvers for the system to retain its pre-fault dynamic performance. Controller reconfiguration is another method to handle faults in the system, for instance by adjusting the controller parameters (coefficients). Both of these two methods have been considered in the literature and are proven to be capable of handling various faults. However, the comparison of these two methods has not been considered sufficiently. In this paper, a controller reconfiguration mechanism and a reference trajectory management are proposed for the spacecraft attitude...
A diversity based reconfigurable method for fault tolerant control of induction motors, Article International Symposium on Power Electronics, Electrical Drives, Automation and Motion, 2006. SPEEDAM 2006, Taormina, 23 May 2006 through 26 May 2006 ; Volume 2006 , 2006 , Pages 66-71 ; 1424401941 (ISBN); 9781424401949 (ISBN) ; Shojaei, A ; Ahmadi Khatir, D ; Sharif University of Technology
AC motor drive systems are sensitive to faults occurring at the power inverter, or at the control system. A novel fault tolerant Field Oriented Control system for induction motors is introduced. The system maintains speed control in the event of sensors malfunction and adverse signal conditions, providing enhanced reliability. The system comprises four different flux estimators which are fused by a Fuzzy aggregation system in order to give a reliable estimate of motor flux. The proposed control system is an effective and easy to implement method giving a potential for motor drive reliability enhancement. © 2006 IEEE
Fault-tolerant five-leg converter topology with FPGA-Based reconfigurable control, Article IEEE Transactions on Industrial Electronics ; Volume 60, Issue 6 , 2013 , Pages 2284-2294 ; 02780046 (ISSN) ; Poure, P ; Saadate, S ; Zolghadri, M. R ; Sharif University of Technology
Fast fault detection and reconfiguration of power converters is necessary in electrical drives to prevent further damage and to make the continuity of service possible. On the other hand, component minimized converters may provide the benefits of higher reliability and less volume and cost. In this paper, a new fault-tolerant converter topology is studied. This converter has five legs before the fault occurrence, and after fault detection the converter continues to function with four legs. A very fast fault detection and reconfiguration scheme is presented and studied. Simulations and experimental tests are performed to evaluate the structure requirements, the digital reconfigurable...
Post Fault Vector Control of CHB Driven Induction Motor, M.Sc. Thesis Sharif University of Technology ; Zolghadri, Mohammad Reza
Multilevel converters are considered recently as one of the industrial solutions for high-power and power quality demanding applications. Casacade H-Bridge (CHB) converter is one of the well known topologies among multilevel converters. CHB converter is characterized by its high modularity allowing its power to be easily increased. Modularity also allows any faulty cell to be isolated, so the load can be fed by the remaining operative cells, which leads to an unbalanced output voltage of the CHB converter. To avoid the unbalanced operation, recently a solution based on modifying the phase and the magnitude of the voltage refereces has been proposed. This thesis presents a method to control...
Fault-Tolerant Control of Flexible Satellite with Magnetic Actuation and Reaction Wheel, M.Sc. Thesis Sharif University of Technology ; Assadian, Nima
The primary goal of this thesis is to develop a Fault Tolerant Control (FTC) system for a flexible satellite in presence of actuators fault and failure. The actuators of the satellite are including three magnetorquers and three reaction wheels on each principal axis. At first, the three-degree-of-freedom rotational motion of a rigid satellite with two flexible solar panels is modeled. The flexible panels are modeled through the assumed mode approach by a finite set of bending modal motion. The ordinary differential equations of their generalized coordinates are found using the Lagrange’s equation. Then, the dynamic model is validated by comparing the simulation results of the model to the NX...
Fault Tolerant Model Predictive Control of Tethered Satellite System, M.Sc. Thesis Sharif University of Technology ; Asadian, Nima
In this thesis, a control method to cope with the fault in the two-satellite two-tether satellite systems has been proposed to avoid failing the mission in the case one tether is torn. A new model for the tethered satellite system with two tethers has been developed to show the effects of tethers’ tension forces in the attitude dynamics. One of the main features of this model is the ability of changing the tethers’ connection points to the co-satellite for attitude control purposes. As a result, tethers’ tension forces are used as control actions to reduce the fuel consumption. The introduced coupled tethered satellite system has been controlled using the model predictive control method....
Fault-Tolerant Attitude Control of Satellite with Thrusters Using μ-synthesis, M.Sc. Thesis Sharif University of Technology ; Assadian, Nima
In this project, a fault-tolerant attitude control system is developed for thruster-driven satellites. The proposed method has the advantage over current state-of-the-art approaches in that it does not require a fault detection and isolation system. Generalized moments are generated by a robust controller that is designed using mixed sensitivity H_∞ and μ-synthesis by DK-iteration. Moreover, a pulse-width modulation technique with quadratic programming optimization is tuned to map the controller outputs to thruster on-off commands as efficiently as possible. The controller is designed to tolerate up to ±30% perturbations in inertia properties and thrust degradations up to 90% of the nominal...
Design of an Adaptive Controller for Uncertain Fractional-order Systems Subject to Actuator Failure, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad
The objective of this research is to design an adaptive controller for a class of fractional-order nonlinear systems in the strict-feedback form with unmodeled dynamics. Actuator saturation and actuator fault are also considered. All of the system states are assumed to be measurable, and all the sensors can be faulty. Fractional-order systems are chosen because, in the modeling of physical systems, the fractional-order calculus is often preferable to the classical integer-order calculus. The controller is designed by using the backstepping design technique. The fuzzy logic systems are used to eliminate the problem of "explosion of complexity" in the conventional backstepping method and also...
Fault-tolerant Control of Formation Flying Satellites Using Machine Learning, M.Sc. Thesis Sharif University of Technology ; Assadian, Nima
In this thesis, a fault-tolerant method for controlling the relative position and attitude between two satellites in a leader and follower formation is proposed. The follower satellite is equipped with twelve thrusters which are installed on the satellite in a particular pattern. These thrusters are assumed to be afflicted by faults. The satellites are subject to external disturbances – such as the ellipsoidal gravity of Earth (J2), drag force, solar radiation pressure, and the third body, and a controller is designed to attain the desired formation under these disturbances.For this purpose, six separated neural networks are trained, one for each of the position or attitude channels. Since...
Wind energy conversion system based on DFIG with open switch fault tolerant six-legs AC-DC-AC converter, Article Proceedings of the IEEE International Conference on Industrial Technology, Cape Town ; February , 2013 , Pages 1656-1661 ; 9781467345699 (ISBN) ; Zolghadri, M. R ; Poure, P ; Saadate, S ; The Institute of Electrical and Electronics Engineers (IEEE); IEEE Industrial Electronics Society (IES); IEEE Technology Management Council; IEEE Region 8; IEEE South Africa Section IE/IA/PEL Joint Chapter ; Sharif University of Technology
Continuity of service of wind energy conversion systems as well as their reliability and performances are some of the major concerns in this power generation area. Six-legs AC/DC/AC converters are normally used in modern wind energy systems like as in the system with a doubly-fed induction generator (DFIG). A sudden failure of the converter can lead to the total or partial loss of the control of the phase currents and can cause serious system malfunction or shutdown. Therefore, to prevent the spread of the fault to the other system components and to ensure continuity of service, fault tolerant converter topologies associated to quick and effective fault detection and compensation methods...