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  • 1.
    Abolmasoumi, Amirhossein
    et al.
    Department of Electrical Engineering, Faculty of Engineering, Arak University.
    Sayyaddelshad, Saleh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Observer design for a class of nonlinear delayed systems with unknown inputs and Markovian jump parameters2012In: ICCAS 2012: 12th International Conference on Control, Automation and Systems, 2012, p. 1848-1852Conference paper (Refereed)
    Abstract [en]

    The problem of full-order observer design for a class of delayed nonlinear systems with unknown inputs and Markovian jumping parameters is considered. The design method is formulated as solving a set of linear matrix inequalities (LMI's). Extending the results of nonlinear observer design to Markovian jump systems with time-varying delays is the main advantages of this paper. The sufficient LMI conditions are dependent on both the upper and lower bounds of delay. The effectiveness of the proposed method is shown via an illustrative example.

  • 2.
    Asheghan, Mohammad Mostafa
    et al.
    Universidad Carlos III de Madrid.
    Sayyaddelshad, Saleh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Beheshti, Mohammad Taghi Hamidi
    Control and Communication Networks Lab, Electrical Engineering Department, Tarbiat Modares University.
    Tavazoeid, Mohammad Saleh
    Electrical Engineering Department, Sharif University of Technology, Tehran.
    Non-fragile control and synchronization of a new fractional order chaotic system2013In: Applied Mathematics and Computation, ISSN 0096-3003, E-ISSN 1873-5649, Vol. 222, p. 712-721Article in journal (Refereed)
    Abstract [en]

    In this paper, we address global non-fragile control and synchronization of a new fractional order chaotic system. First we inspect the chaotic behavior of the fractional order system under study and also find the lowest order (2.49) for the introduced dynamics to remain chaotic. Then, a necessary and sufficient condition which can be easily extended to other fractional-order systems is proposed in terms of Linear Matrix Inequality (LMI) to check whether the candidate state feedback controller with parameter uncertainty can guarantee zero convergence of error or not. In addition, the proposed method provides a global zero attraction of error that guarantees stability around all existing equilibrium points. Finally, numerical simulation are employed to verify the validity of the proposed algorithm.

  • 3.
    Delshad, Saleh Sayyad
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Nonlinear observer design for a class of Lipschitz time-delay systems with unknown inputs: LMI approach2011In: Proceedings of the XXIII International Symposium on Information, Communication and Automation Technologies. (ICAT-2011), Piscataway, NJ: IEEE Communications Society, 2011Conference paper (Refereed)
    Abstract [en]

    In this paper, we consider a method to design a full-order nonlinear observer for a class of nonlinear time-delay systems with unknown inputs. Based on Lyapunov-Krasovskii functional, we derive a sufficient condition for existence of the designed observer which requires solving a set of nonlinear matrix inequalities. Then, the achieved condition is formulated in terms of two linear matrix inequalities (LMIs). Finally, the proposed observer is illustrated with an example.

  • 4.
    Gustafsson, Thomas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sayyaddelshad, Saleh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Björkman, Eric
    Alent Drying AB, Sverige.
    Projekt: Optimal styrning av virkestorkning2012Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    På ett sågverk kan det finnas mer än fyrtio virkestorkar som körs samtidigt. De förses värme från en gemensam värmepanna och restvärmen som inte förbrukas kan användas för att producera elenergi. Den långsiktiga målsättningen är att ta fram ett överordnat system som kan minimera energiförbrukningen med bibehållen torkkvalitet för en grupp av virkestorkar. Systemet skall även klara av att möta de krav på variation i restvärme som kommer från den efterföljande produktionen av elenergi.

  • 5.
    Nikolakopoulos, George
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Dritsas, Leonidas
    University of Patras, Department of Electrical Engineering.
    Sayyaddelshad, Saleh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Combined networked switching output feedback control with D-region stability for performance improvement2014In: International Journal of Control, ISSN 0020-7179, E-ISSN 1366-5820, Vol. 87, no 6, p. 1172-1180Article in journal (Refereed)
    Abstract [en]

    In this article, a combined networked switching output feedback control scheme, with a (Formula presented.)-region stability performance improvement module is presented. The network induced time delays, that are considered to be time varying and integer multiples of the sampling period, are being embedded in the system model, by state augmentation. The resulting model of the overall networked closed-loop system is switching, with the current measured round-trip time delay acting as the switching rule. Based on this modelling approach, a Linear Matrix Inequality (LMI) tuned switching output feedback controller is designed. The proposed approach establishes robustness against time delays and is able to guarantee the overall stability of the switching closed-loop system. Integrated in the controlled synthesis phase, an LMI tuned performance improvement module is being introduced, based on (Formula presented.)-region stability. Multiple simulation results are being presented that prove the efficacy of the proposed scheme.

  • 6.
    Sayyaddelshad, Saleh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Robust observer design for a class of nonlinear systems: LMI approach2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Observer design for nonlinear systems is a well-known problem in control theory that has been studied from different perspectives. Because the system state variables are generally not always available, state estimation is an essential task in many control applications, which is why this problem has attracted considerable attention from researchers and is the main focus of this thesis.Knowing that no mathematical system can exactly model a physical system, as a control engineer we must be aware of how modeling errors might adversely affect the performance of a control system. From the observer perspective, time-delays, uncertainties and unknown inputs are familiar factors that deteriorate the observer performance on the way of design, analysis and synthesis of any type of observer. Every general observer design should be able to treat all (or at least some) of these issues explicitly and provide quantitative and qualitative results about their impact on the observer performance: consequently, the concepts of robustness, robust performance and robust design have recently become common phrases in the literature and constitute an integral part of research on observer design.Compared to the typical linear systems, observer design for nonlinear systems subject to all the aformentioned deteriorative properties presents a greater challenge for control engineers and researchers. In this thesis, the problem of observer design for a class of nonlinear systems, both discrete and continuous-time, subject to time delay, structured uncertainty and unknown inputs, is investigated. The study shows that by using the upper and lower bounds of the time delay, this parameter can be excluded in the observer structure under some constraints. Moreover, a novel method for designing an Unknown Input Observer (UIO) for a class of nonlinear systems is proposed, which makes the observer capable to satisfy desired performance even inthe presence of unknown inputs. Based on the UIO structure, one step further is taken, and a multiobjective optimization approach for state estimation and unknown input reconstruction is proposed that makes the designed observer not only robust against unknown inputs but also able to reconstruct them under some provided linear matrix inequality (LMI) conditions. In light of linear algebra, note that LMI serves as an important tool in this thesis, significantly facilitating the proposed observer designs.

  • 7.
    Sayyaddelshad, Saleh
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    State estimation of nonlinear systems2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Observer design for nonlinear systems is a popular problem in control theory that has beenstudied from many angles. Since the system state variables, in general, are not available, stateestimation is essential in many control applications, which is why the problem is so attractivefor researchers. One example of a process that has nonlinear dynamics is wood drying.In the wood drying process, there are some unmeasurable variables such as the moisturecontent at the surface and inside the wood, which are important for controlling the drying processfor the purpose of minimizing the energy consumption of the wood drying kiln. However,to the best of our knowledge, there is no straightforward observer design for the wood-dryingprocess in the current literature. In the first two research papers that compose this thesis, afterintroducing a state space realization of the wood drying process, a novel method for estimatingthe moisture content of the wood during drying is proposed.Compared to typical systems, observer design for nonlinear uncertain systems with timedelays, is significantly more complicated and thus attractive for research. In this thesis, theproblem of the observer design for a class of uncertain discrete-time nonlinear systems withunknown time delay has also been investigated. The study shows that by using upper and lowerbounds of the time delay, the time delay can be excluded in the observer structure. The thirdand fourth papers mostly focus on this topic based on an optimization approach.

  • 8.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    H∞ observer design for uncertain nonlinear discrete-time systems with time-delay: LMI Optimization Approach2015In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 25, no 10, p. 1514-1527Article in journal (Refereed)
    Abstract [en]

    We present a robust H∞ observer for a class of nonlinear discrete-time systems. The class under study includes an unknown time-varying delay limited by upper and lower bounds, as well as time-varying para- metric uncertainties. We design a nonlinear H∞ observer, by using the upper and lower bounds of the delay, that guarantees asymptotic stability of the estimation error dynamics and is also robust against time-varying parametric uncertainties. The described problem is converted to a standard optimization problem, which can be solved in terms of linear matrix inequalities (LMIs). Then, we expand the problem to a multi-objective optimization problem in which the maximum admissible Lipschitz constant and the minimum disturbance attenuation level are the problem objectives. Finally, the proposed observer is illustrated with two examples.

  • 9.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Observer Design for a Class of Nonlinear Systems Subject to Unknown Inputs2014Conference paper (Refereed)
  • 10.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Observer Design for a Class of Nonlinear Systems Subject to Unknown Inputs2014Conference paper (Other academic)
  • 11.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Observer design for a class of nonlinear systems subject to unknown inputs2014In: 2014 European Control Conference (ECC), June 24-27, 2014. Strasbourg, France, Piscataway, NJ: IEEE Communications Society, 2014, p. 970-974, article id 6862555Conference paper (Refereed)
    Abstract [en]

    We consider a novel method to design an observer for a class of nonlinear discrete-time systems with unknown inputs. Based on Lyapunov functional, we derive a sufficient condition for existence of the designed observer which requires solving a nonlinear matrix inequality. In light of linear algebra, the achieved condition will be formulated in terms of linear matrix inequality (LMI) that can be solved by popular methods easily. Compared to recent researches, the developed approach shows a significant better performance than other techniques previously published in literature and is less conservative in terms of Lipschitz constant. Finally, the proposed observer is illustrated by implementing the proposed method on a single- link flexible manipulator and the results are compared to some recent similar researches in terms of performance and conservativeness.

  • 12.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    State space realization of wood drying process: Modeling, Simulation, and Evaluation in Reality2013In: 2013 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2013, Piscataway, NJ: IEEE Computer Society Press , 2013, p. 4731-4736, article id 6722560Conference paper (Refereed)
    Abstract [en]

    The modeling of a wood drying process using a state space realization is considered. Based on balance equations for energy and mass in the air gap between the timbers, on the wood surface and within the wood, a state space realization consisting of linear and nonlinear parts is proposed which can describe the moisture content and temperature behavior of timber inside a drying kiln. Finally, the proposed state space realization is illustrated with a simulation and achieved results are evaluated by real measurements.

  • 13.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Johansson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    H∞ observer design for uncertain discrete-time nonlinear delay systems: LMI optimization approach2012In: 2012 20th Mediterranean Conference on Control & Automation (MED), Piscataway, NJ: IEEE Communications Society, 2012, p. 592-597Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a robust H∞ observer for a class of nonlinear and uncertain time-delayed systems. To design the proposed observer, the time delay does not have to be exactly known. With knowledge about upper and lower bound of the delay term, we can design an H∞ observer that guarantees asymptotic stability of the estimation error dynamics and is robust against time-varying parametric uncertainties. We show that the described problem can be solved in terms of linear matrix inequalities (LMIs). In addition, the admissible Lipschitz constant of the system is maximized and the disturbance attenuation level is minimized through convex multi-objective optimization. Finally, the proposed observer is illustrated with an example.

  • 14.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Karimi, Hamid Reza
    Department of Engineering, Faculty of Engineering and Science, University of Agder.
    Zemouche, Ali
    Research Center for Automatic Control of Nancy, University of Lorraine.
    Observer-based control design for a class of nonlinear systems subject to unknown inputs: LMI approach2015In: 15th International Conference on Control, Automation and Systems (ICCAS): Busan, Korea (South), 13-16 Oct. 2015, Piscataway, NJ: IEEE Communications Society, 2015, p. 984-989, article id 7364768Conference paper (Refereed)
    Abstract [en]

    This paper deals with the problem of observer-based controller design for a class of nonlinear systems subject to unknown inputs. A novel method is presented to design a controller using estimated state variables which guarantees all the state variables of the closed-loop system converge to the vicinity of the origin and stay there forever. This is done via satisfying several sufficient conditions in terms of nonlinear matrix inequalities. In light of linear algebra, particularly matrix decompositions, the achieved conditions will be converted to a Linear Matrix Inequality (LMI) problem to facilitate the procedure of computing the observer and controller gains. Finally, the effectiveness of the proposed method is illustrated by implementing on a highly nonlinear chaotic system.

  • 15.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Johansson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Darouach, Mohamed
    Université de Lorraine.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    H∞ filter design for state estimation and unknown inputs reconstruction of a class of nonlinear systems2014In: 19th IFAC World Congress on International Federation of Automatic Control: IFAC 2014, Cape Town, South Africa 24 - 29 August 2014, 2014, p. 61-66Conference paper (Refereed)
    Abstract [en]

    We consider a novel method to design a H∞ filter for a class of nonlinear systems subject to unknown inputs. First, we rewrite the system dynamics as a descriptor system. Then, we design a robust H∞ reduced-order filter to estimate both state variables and unknown inputs at the same time. Based on a Lyapunov functional, we derive a sufficient condition for existence of the designed filter which requires solving a nonlinear matrix inequality. The achieved condition is further formulated in terms of a linear matrix inequality (LMI) that is straightforward to solve by popular methods. Finally, the proposed filter is illustrated with an example.

  • 16.
    Sayyaddelshad, Saleh
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Johansson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Darouach, Mohamed
    Université de Lorraine, CRAN-CNRS UMR 7039, IUT de Longwy, 186 Rue de Lorraine.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Robust state estimation and unknown inputs reconstruction for a class of nonlinear systems: multiobjective approach2016In: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 64, p. 1-7Article in journal (Refereed)
    Abstract [en]

    We consider a novel method to design H-infinity observers for a class of uncertain nonlinear systems subject to unknown inputs. First, the main system dynamics are rewritten as an augmented system with state vector including both the state vector of the main system and the unknown inputs. Then, we design a H-infinity reduced-order observer to estimate both state variables and unknown inputs simultaneously. Based on a Lyapunov functional, we derive a sufficient condition for existence of the designed observer which requires solving a nonlinear matrix inequality. To facilitate the observer design, the achieved condition is formulated in terms of a set of linear matrix inequalities (LMI). By extending the proposed method to a multiobjective optimization problem, the maximum bound of the uncertainty and the minimum value of the disturbance attenuation level are found. Finally, the proposed observer is illustrated with an example.

1 - 16 of 16
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