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  Subjects -> COMPUTER SCIENCE (Total: 2050 journals)
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COMPUTER SCIENCE (1196 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 872 Journals sorted alphabetically
3D Printing and Additive Manufacturing     Full-text available via subscription   (Followers: 20)
Abakós     Open Access   (Followers: 4)
ACM Computing Surveys     Hybrid Journal   (Followers: 22)
ACM Journal on Computing and Cultural Heritage     Hybrid Journal   (Followers: 8)
ACM Journal on Emerging Technologies in Computing Systems     Hybrid Journal   (Followers: 11)
ACM Transactions on Accessible Computing (TACCESS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 15)
ACM Transactions on Applied Perception (TAP)     Hybrid Journal   (Followers: 5)
ACM Transactions on Architecture and Code Optimization (TACO)     Hybrid Journal   (Followers: 9)
ACM Transactions on Autonomous and Adaptive Systems (TAAS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Computation Theory (TOCT)     Hybrid Journal   (Followers: 12)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 3)
ACM Transactions on Computer Systems (TOCS)     Hybrid Journal   (Followers: 17)
ACM Transactions on Computer-Human Interaction     Hybrid Journal   (Followers: 14)
ACM Transactions on Computing Education (TOCE)     Hybrid Journal   (Followers: 5)
ACM Transactions on Design Automation of Electronic Systems (TODAES)     Hybrid Journal   (Followers: 3)
ACM Transactions on Economics and Computation     Hybrid Journal  
ACM Transactions on Embedded Computing Systems (TECS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Information Systems (TOIS)     Hybrid Journal   (Followers: 19)
ACM Transactions on Intelligent Systems and Technology (TIST)     Hybrid Journal   (Followers: 7)
ACM Transactions on Interactive Intelligent Systems (TiiS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)     Hybrid Journal   (Followers: 9)
ACM Transactions on Reconfigurable Technology and Systems (TRETS)     Hybrid Journal   (Followers: 6)
ACM Transactions on Sensor Networks (TOSN)     Hybrid Journal   (Followers: 7)
ACM Transactions on Speech and Language Processing (TSLP)     Hybrid Journal   (Followers: 8)
ACM Transactions on Storage     Hybrid Journal  
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 27)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Ad Hoc Networks     Hybrid Journal   (Followers: 11)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Advanced Engineering Materials     Hybrid Journal   (Followers: 28)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advances in Adaptive Data Analysis     Hybrid Journal   (Followers: 7)
Advances in Artificial Intelligence     Open Access   (Followers: 15)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 18)
Advances in Computer Science : an International Journal     Open Access   (Followers: 15)
Advances in Computing     Open Access   (Followers: 2)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 51)
Advances in Engineering Software     Hybrid Journal   (Followers: 27)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 12)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 23)
Advances in Human-Computer Interaction     Open Access   (Followers: 19)
Advances in Materials Sciences     Open Access   (Followers: 14)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 6)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Remote Sensing     Open Access   (Followers: 43)
Advances in Science and Research (ASR)     Open Access   (Followers: 4)
Advances in Technology Innovation     Open Access   (Followers: 5)
AEU - International Journal of Electronics and Communications     Hybrid Journal   (Followers: 8)
African Journal of Information and Communication     Open Access   (Followers: 6)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
AI EDAM     Hybrid Journal  
Air, Soil & Water Research     Open Access   (Followers: 11)
AIS Transactions on Human-Computer Interaction     Open Access   (Followers: 5)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1)
Algorithms     Open Access   (Followers: 11)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 5)
American Journal of Computational Mathematics     Open Access   (Followers: 4)
American Journal of Information Systems     Open Access   (Followers: 5)
American Journal of Sensor Technology     Open Access   (Followers: 4)
Anais da Academia Brasileira de Ciências     Open Access   (Followers: 2)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 7)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Animation Practice, Process & Production     Hybrid Journal   (Followers: 5)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 11)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 12)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Software Engineering     Hybrid Journal   (Followers: 13)
Annual Reviews in Control     Hybrid Journal   (Followers: 6)
Anuario Americanista Europeo     Open Access  
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applied and Computational Harmonic Analysis     Full-text available via subscription   (Followers: 1)
Applied Artificial Intelligence: An International Journal     Hybrid Journal   (Followers: 13)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Clinical Informatics     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 11)
Applied Computer Systems     Open Access   (Followers: 2)
Applied Informatics     Open Access  
Applied Mathematics and Computation     Hybrid Journal   (Followers: 33)
Applied Medical Informatics     Open Access   (Followers: 10)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Soft Computing     Hybrid Journal   (Followers: 16)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Applied System Innovation     Open Access  
Architectural Theory Review     Hybrid Journal   (Followers: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5)
Archive of Numerical Software     Open Access  
Archives and Museum Informatics     Hybrid Journal   (Followers: 130)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 5)
arq: Architectural Research Quarterly     Hybrid Journal   (Followers: 7)
Artifact     Hybrid Journal   (Followers: 2)
Artificial Life     Hybrid Journal   (Followers: 7)
Asia Pacific Journal on Computational Engineering     Open Access  
Asia-Pacific Journal of Information Technology and Multimedia     Open Access   (Followers: 1)
Asian Journal of Computer Science and Information Technology     Open Access  
Asian Journal of Control     Hybrid Journal  
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
Australian Educational Computing     Open Access   (Followers: 1)
Automatic Control and Computer Sciences     Hybrid Journal   (Followers: 4)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Automatica     Hybrid Journal   (Followers: 11)
Automation in Construction     Hybrid Journal   (Followers: 6)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Basin Research     Hybrid Journal   (Followers: 5)
Behaviour & Information Technology     Hybrid Journal   (Followers: 52)
Big Data and Cognitive Computing     Open Access   (Followers: 2)
Biodiversity Information Science and Standards     Open Access  
Bioinformatics     Hybrid Journal   (Followers: 283)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 19)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 35)
Briefings in Bioinformatics     Hybrid Journal   (Followers: 44)
British Journal of Educational Technology     Hybrid Journal   (Followers: 142)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
c't Magazin fuer Computertechnik     Full-text available via subscription   (Followers: 1)
CALCOLO     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Journal of Electrical and Computer Engineering     Full-text available via subscription   (Followers: 14)
Capturing Intelligence     Full-text available via subscription  
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cell Communication and Signaling     Open Access   (Followers: 2)
Central European Journal of Computer Science     Hybrid Journal   (Followers: 5)
CERN IdeaSquare Journal of Experimental Innovation     Open Access   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
ChemSusChem     Hybrid Journal   (Followers: 7)
China Communications     Full-text available via subscription   (Followers: 7)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
CIN Computers Informatics Nursing     Full-text available via subscription   (Followers: 11)
Circuits and Systems     Open Access   (Followers: 15)
Clean Air Journal     Full-text available via subscription   (Followers: 1)
CLEI Electronic Journal     Open Access  
Clin-Alert     Hybrid Journal   (Followers: 1)
Cluster Computing     Hybrid Journal   (Followers: 1)
Cognitive Computation     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combinatorics, Probability and Computing     Hybrid Journal   (Followers: 4)
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Communication Methods and Measures     Hybrid Journal   (Followers: 12)
Communication Theory     Hybrid Journal   (Followers: 20)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Algebra     Hybrid Journal   (Followers: 3)
Communications in Computational Physics     Full-text available via subscription   (Followers: 2)
Communications in Partial Differential Equations     Hybrid Journal   (Followers: 3)
Communications of the ACM     Full-text available via subscription   (Followers: 52)
Communications of the Association for Information Systems     Open Access   (Followers: 16)
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering     Hybrid Journal   (Followers: 3)
Complex & Intelligent Systems     Open Access   (Followers: 1)
Complex Adaptive Systems Modeling     Open Access  
Complex Analysis and Operator Theory     Hybrid Journal   (Followers: 2)
Complexity     Hybrid Journal   (Followers: 6)
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 8)
Computación y Sistemas     Open Access  
Computation     Open Access  
Computational and Applied Mathematics     Hybrid Journal   (Followers: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Astrophysics and Cosmology     Open Access   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computational Cognitive Science     Open Access   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Condensed Matter     Open Access  
Computational Ecology and Software     Open Access   (Followers: 9)
Computational Economics     Hybrid Journal   (Followers: 9)
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Linguistics     Open Access   (Followers: 23)
Computational Management Science     Hybrid Journal  
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 5)
Computational Methods and Function Theory     Hybrid Journal  
Computational Molecular Bioscience     Open Access   (Followers: 2)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Particle Mechanics     Hybrid Journal   (Followers: 1)
Computational Research     Open Access   (Followers: 1)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computational Science and Techniques     Open Access  
Computational Statistics     Hybrid Journal   (Followers: 14)
Computational Statistics & Data Analysis     Hybrid Journal   (Followers: 30)
Computer     Full-text available via subscription   (Followers: 94)
Computer Aided Surgery     Hybrid Journal   (Followers: 6)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 8)
Computer Communications     Hybrid Journal   (Followers: 10)
Computer Engineering and Applications Journal     Open Access   (Followers: 5)
Computer Journal     Hybrid Journal   (Followers: 9)
Computer Methods in Applied Mechanics and Engineering     Hybrid Journal   (Followers: 23)
Computer Methods in Biomechanics and Biomedical Engineering     Hybrid Journal   (Followers: 12)
Computer Methods in the Geosciences     Full-text available via subscription   (Followers: 2)
Computer Music Journal     Hybrid Journal   (Followers: 19)

        1 2 3 4 5 6 | Last

Journal Cover Automatica
  [SJR: 4.315]   [H-I: 188]   [11 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0005-1098
   Published by Elsevier Homepage  [3176 journals]
  • Scattering-based stabilization of non-planar conic systems
    • Authors: Anastasiia A. Usova; Ilia G. Polushin; Rajni V. Patel
      Pages: 1 - 11
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Anastasiia A. Usova, Ilia G. Polushin, Rajni V. Patel
      Methods for scattering-based stabilization of interconnections of nonlinear systems are developed for the case where the subsystems are non-planar conic. The notion of non-planar conicity is a generalization of the conicity notion to the case where the cone’s center is a subspace with dimension greater than one. For a feedback interconnection of non-planar conic systems, a graph separation condition for finite-gain L 2 -stability is derived in terms of relationship between the maximal singular value of the product of projection operators onto the subsystems’ central subspaces and the radii of the corresponding cones. Furthermore, a new generalized scattering transformation is developed that allows for rendering the dynamic characteristics of a non-planar conic system into an arbitrary prescribed cone with compatible dimensions. The new scattering transformation is subsequently applied to the problem of stabilization of interconnections of non-planar conic systems, with and without communication delays. Applications of the developed scattering-based stabilization methods to the problems of stable robot–environment interaction and bilateral teleoperation with multiple heterogeneous communication delays are discussed.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.028
      Issue No: Vol. 93 (2018)
       
  • A necessary and sufficient condition for stability of LMS-based consensus
           adaptive filters
    • Authors: Siyu Xie; Lei Guo
      Pages: 12 - 19
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Siyu Xie, Lei Guo
      This paper investigates the stability and performance of the standard least mean squares (LMS)-based consensus adaptive filters under a changing network topology. We first analyze the stability for possibly unbounded, non-independent and non-stationary signals, by introducing an information condition that can be shown to be not only sufficient but also necessary for the global stability. We also demonstrate that the distributed adaptive filters can estimate a dynamic process of interest from noisy measurements by a set of sensors working in a collaborative manner, in the natural scenario where none of the sensors can fulfill the estimation task individually. Furthermore, we give an analysis of the filtering error under various assumptions without stationarity and independency constraints on the system signals, and thus do not exclude applications to stochastic systems with feedback. In contrast to the analyses of the normalized LMS-based distributed adaptive filters, we need to use stochastic averaging theorems in the stability analysis due to possible unboundedness of the system signals.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.027
      Issue No: Vol. 93 (2018)
       
  • Dynamic controllers for column synchronization of rotation matrices: A
           QR-factorization approach
    • Authors: Johan Thunberg; Johan Markdahl; Jorge Gonçalves
      Pages: 20 - 25
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Johan Thunberg, Johan Markdahl, Jorge Gonçalves
      In the multi-agent systems setting, this paper addresses continuous-time distributed synchronization of columns of rotation matrices. More precisely, k specific columns shall be synchronized and only the corresponding k columns of the relative rotations between the agents are assumed to be available for the control design. When one specific column is considered, the problem is equivalent to synchronization on the ( d − 1 ) -dimensional unit sphere and when all the columns are considered, the problem is equivalent to synchronization on SO ( d ) . We design dynamic control laws for these synchronization problems. The control laws are based on the introduction of auxiliary variables in combination with a QR-factorization approach. The benefit of this QR-factorization approach is that we can decouple the dynamics for the k columns from the remaining d − k ones. Under the control scheme, the closed loop system achieves almost global convergence to synchronization for quasi-strong interaction graph topologies.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.023
      Issue No: Vol. 93 (2018)
       
  • Output formation-containment of interacted heterogeneous linear systems by
           distributed hybrid active control
    • Authors: Yan-Wu Wang; Xiao-Kang Liu; Jiang-Wen Xiao; Yanjun Shen
      Pages: 26 - 32
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Yan-Wu Wang, Xiao-Kang Liu, Jiang-Wen Xiao, Yanjun Shen
      This paper investigates the output formation-containment problem of interacted heterogeneous linear systems, where each heterogeneous system, whether the leader or the follower, has different dimensions and dynamics. Different from existing literature, discrete-time communication manner is deployed to reduce the communication consumption. By the impulsive control method, a distributed hybrid active controller is designed using the discrete-time information of neighbors. It achieves the output formation-containment of heterogeneous systems if two related conditions are satisfied, namely, local linear matrix inequalities (LMIs) and a bounded constraint on the average interacted interval. Moreover, the controller parameter design is further simplified by replacing the LMI condition with a Hurwitz condition, which can be easily guaranteed by solving a Riccati equation. Finally, a numerical example is provided to demonstrate the effectiveness of the theoretical result.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.020
      Issue No: Vol. 93 (2018)
       
  • Asynchronous sliding mode control of Markovian jump systems with
           time-varying delays and partly accessible mode detection probabilities
    • Authors: Jun Song; Yugang Niu; Yuanyuan Zou
      Pages: 33 - 41
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Jun Song, Yugang Niu, Yuanyuan Zou
      In this work, the problem of asynchronous sliding mode control (SMC) is investigated for a class of uncertain Markovian jump systems (MJSs) with time-varying delays and stochastic perturbation. It is assumed that the system modes cannot be obtained synchronously by the controller, but instead there is a detector that provides estimated values of the system modes. This asynchronous phenomenon between the system modes and controller modes will be described in this work via a hidden Markov model with partly accessible mode detection probabilities. Based on a common sliding surface, an asynchronous SMC law depending on the detector mode is synthesized to ensure the mean square stability of the sliding mode dynamics and the reachability of the specified sliding surface simultaneously. Moreover, a design algorithm for obtaining the asynchronous SMC law is established. Finally, an application of the automotive electronic throttle system is provided to illustrate the effectiveness and advantages of the proposed asynchronous sliding mode control approach.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.037
      Issue No: Vol. 93 (2018)
       
  • Design of robust fuzzy fault detection filter for polynomial fuzzy systems
           with new finite frequency specifications
    • Authors: Ali Chibani; Mohammed Chadli; Steven X. Ding; Naceur Benhadj Braiek
      Pages: 42 - 54
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Ali Chibani, Mohammed Chadli, Steven X. Ding, Naceur Benhadj Braiek
      This paper investigates the problem of fault detection filter design for discrete-time polynomial fuzzy systems with faults and unknown disturbances. The frequency ranges of the faults and the disturbances are assumed to be known beforehand and to reside in low, middle or high frequency ranges. Thus, the proposed filter is designed in the finite frequency range to overcome the conservatism generated by those designed in the full frequency domain. Being of polynomial fuzzy structure, the proposed filter combines the H − / H ∞ performances in order to ensure the best robustness to the disturbance and the best sensitivity to the fault. Design conditions are derived in Sum Of Squares formulations that can be easily solved via available software tools. Two illustrative examples are introduced to demonstrate the effectiveness of the proposed method and a comparative study with LMI method is also provided.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.024
      Issue No: Vol. 93 (2018)
       
  • A hybrid stochastic game for secure control of cyber-physical systems
    • Authors: Fei Miao; Quanyan Zhu; Miroslav Pajic; George J. Pappas
      Pages: 55 - 63
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Fei Miao, Quanyan Zhu, Miroslav Pajic, George J. Pappas
      In this paper, we establish a zero-sum, hybrid state stochastic game model for designing defense policies for cyber-physical systems against different types of attacks. With the increasingly integrated properties of cyber-physical systems (CPS) today, security is a challenge for critical infrastructures. Though resilient control and detecting techniques for a specific model of attack have been proposed, to analyze and design detection and defense mechanisms against multiple types of attacks for CPSs requires new system frameworks. Besides security, other requirements such as optimal control cost also need to be considered. The hybrid game model we propose contains physical states that are described by the system dynamics, and a cyber state that represents the detection mode of the system composed by a set of subsystems. A strategy means selecting a subsystem by combining one controller, one estimator and one detector among a finite set of candidate components at each state. Based on the game model, we propose a suboptimal value iteration algorithm for a finite horizon game, and prove that the algorithm results an upper bound for the value of the finite horizon game. A moving-horizon approach is also developed in order to provide a scalable and real-time computation of the switching strategies. Both algorithms aim at obtaining a saddle-point equilibrium policy for balancing the system’s security overhead and control cost. The paper illustrates these concepts using numerical examples, and we compare the results with previously system designs that only equipped with one type of controller.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.012
      Issue No: Vol. 93 (2018)
       
  • Stabilization and control Lyapunov functions for language constrained
           discrete-time switched linear systems
    • Authors: Mirko Fiacchini; Marc Jungers; Antoine Girard
      Pages: 64 - 74
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Mirko Fiacchini, Marc Jungers, Antoine Girard
      In this paper, the stabilizability of discrete-time switched linear systems subject to constraints on the switching law is considered. The admissible switching sequences are given by the language generated by a nondeterministic finite state automaton. Constructive necessary and sufficient conditions for recurrent stabilizability are given and the exact relations with the existence of control Lyapunov functions and with general stabilizability are provided. The dependence of stabilizability on the automaton initial state is also proved.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.039
      Issue No: Vol. 93 (2018)
       
  • A distributed Kalman filter with event-triggered communication and
           guaranteed stability
    • Authors: Giorgio Battistelli; Luigi Chisci; Daniela Selvi
      Pages: 75 - 82
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Giorgio Battistelli, Luigi Chisci, Daniela Selvi
      The paper addresses Kalman filtering over a peer-to-peer sensor network with a careful eye towards data transmission scheduling for reduced communication bandwidth and, consequently, enhanced energy efficiency and prolonged network lifetime. A novel consensus Kalman filter algorithm with event-triggered communication is developed by enforcing each node to transmit its local information to the neighbors only when this is considered as particularly significant for estimation purposes, in the sense that it notably deviates from the information that can be predicted from the last transmitted one. Further, it is proved how the filter guarantees stability (mean-square boundedness of the estimation error in each node) under network connectivity and system collective observability. Finally, numerical simulations are provided to demonstrate practical effectiveness of the distributed filter for trading off estimation performance versus transmission rate.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.005
      Issue No: Vol. 93 (2018)
       
  • Dynamic output feedback stabilization of switched linear systems with
           delay via a trajectory based approach
    • Authors: Saeed Ahmed; Frédéric Mazenc; Hitay Özbay
      Pages: 92 - 97
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Saeed Ahmed, Frédéric Mazenc, Hitay Özbay
      A new technique is proposed to construct observers and to achieve output feedback stabilization of a class of continuous-time switched linear systems with a time-varying delay in the output. The delay is a piecewise continuous bounded function of time and no constraint is imposed on the delay derivative. For stability analysis, an extension of a recent trajectory based approach is used; this is fundamentally different from classical Lyapunov function based methods. A stability condition is given in terms of the upper bound on the time-varying delay to ensure global uniform exponential stability of the switched feedback system. The main result applies in cases where some of the subsystems of the switched system are not stabilizable and not detectable.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.072
      Issue No: Vol. 93 (2018)
       
  • Adaptive control of a class of strict-feedback time-varying nonlinear
           systems with unknown control coefficients
    • Authors: Jiangshuai Huang; Wei Wang; Changyun Wen; Jing Zhou
      Pages: 98 - 105
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Jiangshuai Huang, Wei Wang, Changyun Wen, Jing Zhou
      In this paper, robust adaptive control of a class of strict-feedback nonlinear systems with unknown control directions is investigated. A novel Nussbaum-type function is developed and a key theorem is drawn which involves quantifying the addition of multiple Nussbaum functions with different control directions in a single inequality. Global stability of the closed-loop system and asymptotic stabilization of system output are proved. A simulation example is given to illustrate the effectiveness of the proposed control scheme.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.061
      Issue No: Vol. 93 (2018)
       
  • Recursive identification of systems with binary-valued outputs and with
           ARMA noises
    • Authors: Qijiang Song
      Pages: 106 - 113
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Qijiang Song
      This paper considers the identification problem of the ARMA system followed by a binary sensor, in which the internal variables are corrupted by additive ARMA noises. Recursive estimates for the parameters of the linear system and for the threshold of the binary sensor are given by the stochastic approximation algorithms with expanding truncations (SAAWET). Under reasonable conditions, all the estimates are proved to be convergent to the true values with probability one. The almost surely convergence rates are also investigated. A simulation example is included to justify the theoretical results.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.059
      Issue No: Vol. 93 (2018)
       
  • Signed bounded confidence models for opinion dynamics
    • Authors: Claudio Altafini; Francesca Ceragioli
      Pages: 114 - 125
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Claudio Altafini, Francesca Ceragioli
      The aim of this paper is to modify continuous-time bounded confidence opinion dynamics models so that “changes of opinion” (intended as changes of the sign of the initial states) are never induced during the evolution. Such sign invariance can be achieved by letting opinions of different sign localized near the origin interact negatively, or neglect each other, or even repel each other. In all cases, it is possible to obtain sign-preserving bounded confidence models with state-dependent connectivity and with a clustering behavior similar to that of a standard bounded confidence model.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.064
      Issue No: Vol. 93 (2018)
       
  • Distributed time synchronization for networks with random delays and
           measurement noise
    • Authors: Miloš S. Stanković; Srdjan S. Stanković; Karl Henrik Johansson
      Pages: 126 - 137
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Miloš S. Stanković, Srdjan S. Stanković, Karl Henrik Johansson
      In this paper a new distributed asynchronous algorithm is proposed for time synchronization in networks with random communication delays, measurement noise and communication dropouts. Three different types of the drift correction algorithm are introduced, based on different kinds of local time increments. Under nonrestrictive conditions concerning network properties, it is proved that all the algorithm types provide convergence in the mean square sense and with probability one (w.p.1) of the corrected drifts of all the nodes to the same value (consensus). An estimate of the convergence rate of these algorithms is derived. For offset correction, a new algorithm is proposed containing a compensation parameter coping with the influence of random delays and special terms taking care of the influence of both linearly increasing time and drift correction. It is proved that the corrected offsets of all the nodes converge in the mean square sense and w.p.1. An efficient offset correction algorithm based on consensus on local compensation parameters is also proposed. It is shown that the overall time synchronization algorithm can also be implemented as a flooding algorithm with one reference node. It is proved that it is possible to achieve bounded error between local corrected clocks in the mean square sense and w.p.1. Simulation results provide an additional practical insight into the algorithm properties and show its advantage over the existing methods.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.054
      Issue No: Vol. 93 (2018)
       
  • Cooperative global robust output regulation for a class of nonlinear
           multi-agent systems by distributed event-triggered control
    • Authors: Wei Liu; Jie Huang
      Pages: 138 - 148
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Wei Liu, Jie Huang
      This paper studies the event-triggered cooperative global robust output regulation problem for a class of nonlinear multi-agent systems via a distributed internal model design. We show that our problem can be solved practically in the sense that the ultimate bound of the tracking error can be made arbitrarily small by adjusting a design parameter in the proposed event-triggered mechanism. Our result offers a few new features. First, our control law is robust against both external disturbances and parameter uncertainties, which are allowed to belong to some arbitrarily large prescribed compact sets. Second, the nonlinear functions in our system do not need to satisfy the global Lipschitz condition. Thus our systems are general enough to include some benchmark nonlinear systems that cannot be handled by existing approaches. Finally, our control law is a specific distributed output-based event-triggered control law, which lends itself to a direct digital implementation.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.062
      Issue No: Vol. 93 (2018)
       
  • Linear predictors for nonlinear dynamical systems: Koopman operator meets
           model predictive control
    • Authors: Milan Korda; Igor Mezić
      Pages: 149 - 160
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Milan Korda, Igor Mezić
      This paper presents a class of linear predictors for nonlinear controlled dynamical systems. The basic idea is to lift (or embed) the nonlinear dynamics into a higher dimensional space where its evolution is approximately linear. In an uncontrolled setting, this procedure amounts to numerical approximations of the Koopman operator associated to the nonlinear dynamics. In this work, we extend the Koopman operator to controlled dynamical systems and apply the Extended Dynamic Mode Decomposition (EDMD) to compute a finite-dimensional approximation of the operator in such a way that this approximation has the form of a linear controlled dynamical system. In numerical examples, the linear predictors obtained in this way exhibit a performance superior to existing linear predictors such as those based on local linearization or the so called Carleman linearization. Importantly, the procedure to construct these linear predictors is completely data-driven and extremely simple – it boils down to a nonlinear transformation of the data (the lifting) and a linear least squares problem in the lifted space that can be readily solved for large data sets. These linear predictors can be readily used to design controllers for the nonlinear dynamical system using linear controller design methodologies. We focus in particular on model predictive control (MPC) and show that MPC controllers designed in this way enjoy computational complexity of the underlying optimization problem comparable to that of MPC for a linear dynamical system with the same number of control inputs and the same dimension of the state-space. Importantly, linear inequality constraints on the state and control inputs as well as nonlinear constraints on the state can be imposed in a linear fashion in the proposed MPC scheme. Similarly, cost functions nonlinear in the state variable can be handled in a linear fashion. We treat both the full-state measurement case and the input–output case, as well as systems with disturbances/noise. Numerical examples demonstrate the approach. 1

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.046
      Issue No: Vol. 93 (2018)
       
  • Trajectory curvature guidance for Mars landings in hazardous terrains
    • Authors: Pingyuan Cui; Tong Qin; Shengying Zhu; Yang Liu; Rui Xu; Zhengshi Yu
      Pages: 161 - 171
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Pingyuan Cui, Tong Qin, Shengying Zhu, Yang Liu, Rui Xu, Zhengshi Yu
      Focusing on the trajectory curvature, this paper presents an innovative and analytical guidance law for the construction of geometrically convex trajectories. Moving along such trajectories, the lander can increase the probability of a safe landing in hazardous terrains. Initially, the curvature theorems of the powered descent trajectories are developed. In these theorems, the inner relationship between trajectory curvature and lander states is revealed, and the state constraints for a geometrically convex trajectory are derived. Next, the trajectory curvature guidance is developed in an analytical formulation by satisfying the state constraints for a convex trajectory, and the selection of the key guidance parameters is investigated. Finally, the performance of the trajectory curvature guidance is analyzed in detail, illustrating its superior hazard avoidance and the camera’s field of view.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.049
      Issue No: Vol. 93 (2018)
       
  • Coupling based estimation approaches for the average reward performance
           potential in Markov chains
    • Authors: Yanjie Li; Xinyu Wu; Yunjiang Lou; Haoyao Chen; Jiangang Li
      Pages: 172 - 182
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Yanjie Li, Xinyu Wu, Yunjiang Lou, Haoyao Chen, Jiangang Li
      Performance potential is an important concept in the sensitivity analysis of Markov chains. The estimation of performance potential provides the basis for the simulation-based optimization and sensitivity analysis of Markov chains. In this study, we present novel estimation approaches for the average reward (or cost) performance potential by combining perturbation realization factors and coupling techniques for Markov chains with finite state space. These approaches can effectively implement estimation with geometric variance reduction for average reward performance potential. Meanwhile, a number of coupling methods, including two optimal coupling methods, can be applied to further reduce estimation variance or simulation time. The numerical tests show that our approaches can significantly enhance the simulation efficiency.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.011
      Issue No: Vol. 93 (2018)
       
  • Suppressing phase damping decoherence by periodical imperfect projective
           measurements
    • Authors: Bo-Yang Liu; Ming Zhang; Peng Kang; Hong-Yi Dai
      Pages: 183 - 188
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Bo-Yang Liu, Ming Zhang, Peng Kang, Hong-Yi Dai
      We explore how to overcome phase damping decoherence when imperfect projective measurements are available. It is demonstrated that a “relaxed” control goal may be achieved by combining simple open-loop coherent control with periodic imperfect projective measurements. Inspired by the idea of soft optimization, we propose to control the state of a qubit staying near a reference pure state with high probability for a sufficiently long time. This “relaxed” control goal is expressed in terms of three-parameter performance indexes, and it is in remarked contrast to the “hard” requirement that the state of the controlled qubit always stays at the reference pure state. We not only establish necessary conditions for relaxed robust problems, but also present sufficient conditions for the existence of a solution to the relaxed robust problems. With the help of main results, one can estimate how the maximal total time depends on the target state and the perturbation bounds. Furthermore, it is demonstrated that imperfect realization of projective measurements will worsen the three-parameter performance indexes.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.045
      Issue No: Vol. 93 (2018)
       
  • Extremum seeking-based perfect adaptive tracking of non-PE references
           despite nonvanishing variance of perturbation
    • Authors: Miloje S. Radenković; Miroslav Krstić
      Pages: 189 - 196
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Miloje S. Radenković, Miroslav Krstić
      This paper presents a novel algorithm for adaptive stabilization of unstable discrete time systems with unknown control directions. In a departure from commonly used recursive least squares and gradient type parameter estimators, the proposed algorithm is based on extremum seeking (ES) method. The perturbation signal is a martingale difference sequence (m.d.s) with a non-decaying (bounded from below) variance. In spite of a non-vanishing perturbation, somewhat surprisingly it is shown that globally, almost surely (a.s.) the tracking error converges to zero, input and output signals are uniformly bounded, and the parameter estimates are convergent sequences.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.068
      Issue No: Vol. 93 (2018)
       
  • Pointwise exponential stabilization of a linear parabolic PDE system using
           non-collocated pointwise observation
    • Authors: Jun-Wei Wang; Ya-Qiang Liu; Chang-Yin Sun
      Pages: 197 - 210
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Jun-Wei Wang, Ya-Qiang Liu, Chang-Yin Sun
      This paper deals with the problem of exponential stabilization for a linear distributed parameter system (DPS) using pointwise control and non-collocated pointwise observation, where the system is modeled by a parabolic partial differential equation (PDE). The main objective of this paper is to construct an output feedback controller for pointwise exponential stabilization of the linear parabolic PDE system using the non-collocated pointwise observation. The observer-based output feedback control technique is utilized to overcome the design difficulty caused by the non-collocation pointwise observation. We construct a Luenberger-type PDE state observer to exponentially track the state of the PDE system. A collocated pointwise feedback controller is proposed based on the estimated state. A variation of Poincaré – Wirtinger inequality is derived and the spatial domain is decomposed into multiple sub-domains according to the number of the actuators and sensors. By using Lyapunov’s direct method, integration by parts, and the variation of Poincaré – Wirtinger inequality at each sub-domain, sufficient conditions for the existence of the observer-based out feedback controller are developed such that the resulting closed-loop system is exponentially stable, and presented in terms of standard linear matrix inequalities (LMIs). Furthermore, the closed-loop well-posedness analysis is also provided by the C 0 -semigroup approach. Extensive numerical simulation results are presented to show the performance of the proposed output feedback controller.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.015
      Issue No: Vol. 93 (2018)
       
  • Distributed Pareto-optimal state estimation using sensor networks
    • Authors: Francesca Boem; Yilun Zhou; Carlo Fischione; Thomas Parisini
      Pages: 211 - 223
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Francesca Boem, Yilun Zhou, Carlo Fischione, Thomas Parisini
      A novel model-based dynamic distributed state estimator is proposed using sensor networks. The estimator consists of a filtering step – which uses a weighted combination of information provided by the sensors – and a model-based predictor of the system’s state. The filtering weights and the model-based prediction parameters jointly minimize – at each time-step – the bias and the variance of the prediction error in a Pareto optimization framework. The simultaneous distributed design of the filtering weights and of the model-based prediction parameters is considered, differently from what is normally done in the literature. It is assumed that the weights of the filtering step are in general unequal for the different state components, unlike existing consensus-based approaches. The state, the measurements, and the noise components are allowed to be individually correlated, but no probability distribution knowledge is assumed for the noise variables. Each sensor can measure only a subset of the state variables. The convergence properties of the mean and of the variance of the prediction error are demonstrated, and they hold both for the global and the local estimation errors at any network node. Simulation results illustrate the performance of the proposed method, obtaining better results than state of the art distributed estimation approaches.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.071
      Issue No: Vol. 93 (2018)
       
  • Optimizing Kalman optimal observer for state affine systems by input
           selection
    • Authors: Ignacio Rubio Scola; Gildas Besançon; Didier Georges
      Pages: 224 - 230
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Ignacio Rubio Scola, Gildas Besançon, Didier Georges
      In this paper, a new algorithm to build an optimal input for state reconstruction in the class of state-affine systems is proposed, in the sense that it enhances the performances of a Kalman-like observer, as well as it guarantees the system observability. The approach relies on the fact that for a state-affine system, as soon as the input is defined as a function of time, Kalman filtering theory can be applied. In fact, it is first highlighted how an appropriate choice of the system input can improve the Kalman filtering performance in this case. It is then emphasized how this input selection amounts to a control problem, which can be solved by an appropriate optimization algorithm. Finally, the algorithm is applied to a case of fault detection in a pipeline as an illustrative example, with some simulation results showing the observer performance improvement with the proposed input.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.060
      Issue No: Vol. 93 (2018)
       
  • Active vibration control of a flexible rod moving in water: Application to
           nuclear refueling machines
    • Authors: Umer Hameed Shah; Keum-Shik Hong
      Pages: 231 - 243
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Umer Hameed Shah, Keum-Shik Hong
      This paper addresses a simultaneous control of the positions of the bridge and trolley and the vibrations of the load of a nuclear refueling machine (RM) that transports nuclear fuel rods to given locations in the nuclear reactor. Hamilton’s principle is used to develop the equations of motion of the RM. The lateral and transverse vibrations of the fuel rods during their transportation in water are analyzed. In deriving the control law, the nonlinear hydrodynamic forces acting on the rod are considered. Then, a boundary control scheme is developed, which suppresses the lateral and transverse vibrations simultaneously in the course of the transportation of the fuel rod to the desired locations. Furthermore, Lyapunov function-based stability analyses are performed to prove the uniform ultimate boundedness of the closed loop system as well as the simultaneous control of the positions of the bridge and trolley under the influence of nonlinear hydrodynamic forces. Finally, experimental and simulation results are provided to demonstrate the effectiveness of the proposed control scheme.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.048
      Issue No: Vol. 93 (2018)
       
  • A decentralized energy-optimal control framework for connected automated
           vehicles at signal-free intersections
    • Authors: Andreas A. Malikopoulos; Christos G. Cassandras; Yue J. Zhang
      Pages: 244 - 256
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Andreas A. Malikopoulos, Christos G. Cassandras, Yue J. Zhang
      We address the problem of optimally controlling connected and automated vehicles (CAVs) crossing an urban intersection without any explicit traffic signaling, so as to minimize energy consumption subject to a throughput maximization requirement. We show that the solution of the throughput maximization problem depends only on the hard safety constraints imposed on CAVs and its structure enables a decentralized optimal control problem formulation for energy minimization. We present a complete analytical solution of these decentralized problems and derive conditions under which feasible solutions satisfying all safety constraints always exist. The effectiveness of the proposed solution is illustrated through simulation which shows substantial dual benefits of the proposed decentralized framework by allowing CAVs to conserve momentum and fuel while also improving travel time.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.056
      Issue No: Vol. 93 (2018)
       
  • Synthesis of virtual holonomic constraints for obtaining stable constraint
           dynamics
    • Authors: Alessandro Costalunga; Luca Consolini
      Pages: 262 - 273
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Alessandro Costalunga, Luca Consolini
      A virtual holonomic constraint (VHC) is a relation among the generalized coordinates of a mechanical system that can be made invariant via feedback control. The autonomous dynamics of the system resulting on the enforcement of the VHC are called the constraint dynamics. This work presents a method for the synthesis of VHCs that guarantees the existence of an asymptotically stable limit cycle on the constraint dynamics.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.030
      Issue No: Vol. 93 (2018)
       
  • Global robust output tracking control for a class of uncertain cascaded
           nonlinear systems
    • Authors: Jiang-Bo Yu; Yan Zhao; Yu-Qiang Wu
      Pages: 274 - 281
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Jiang-Bo Yu, Yan Zhao, Yu-Qiang Wu
      This paper focuses on the global robust output tracking control for a class of uncertain cascaded nonlinear systems. Using only the measured output, we present a dynamic output feedback λ -tracking control scheme in a recursive method. Without the assistance of some kind of high-gain observers, we employ a reduced-order observer to rebuild the unmeasured states. The dynamic adaptation switching mechanism plays a key role in achieving the output λ -tracking. It is shown that the designed λ -tracker guarantees the system output track any desired reference signal with prescribed accuracy, and keep all signals in the closed-loop system globally bounded. A chaos control application in the fourth-order generalized Lorenz systems demonstrates the efficacy of the proposed control strategy.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.018
      Issue No: Vol. 93 (2018)
       
  • A two-experiment approach to Wiener system identification
    • Authors: Giulio Bottegal; Ricardo Castro-Garcia; Johan A.K. Suykens
      Pages: 282 - 289
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Giulio Bottegal, Ricardo Castro-Garcia, Johan A.K. Suykens
      We propose a new methodology for identifying Wiener systems using the data acquired from two separate experiments. In the first experiment, we feed the system with a sinusoid at a prescribed frequency and use the steady state response of the system to estimate the static nonlinearity. In the second experiment, the estimated nonlinearity is used to identify a model of the linear block, feeding the system with a persistently exciting input. We discuss both parametric and nonparametric approaches to estimate the static nonlinearity. In the parametric case, we show that modeling the static nonlinearity as a polynomial results into a fast least-squares based estimation procedure. In the nonparametric case, least squares support vector machines (LS-SVM) are employed to obtain a flexible model. The effectiveness of the method is demonstrated through numerical experiments.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.069
      Issue No: Vol. 93 (2018)
       
  • Switching and sweeping vibration absorbers: Theory and experimental
           validation
    • Authors: Stefano Miani; Michele Zilletti; Paolo Gardonio; Franco Blanchini; Patrizio Colaneri
      Pages: 290 - 301
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Stefano Miani, Michele Zilletti, Paolo Gardonio, Franco Blanchini, Patrizio Colaneri
      This paper investigates the principal properties of time varying operation modes for tuneable vibration absorbers mounted on distributed structures to reduce vibrations produced by stationary broad frequency band disturbances. The study considers a practical application where an electro-mechanical tuneable vibration absorber, comprising a seismic coil-magnet linear transducer, is fixed on a thin walled circular duct flexible structure. The absorber is commanded to either periodically switch or continuously vary the stiffness and damping of the elastic suspension holding the moving magnet. As a result, the tuneable vibration absorber fundamental natural frequency and damping ratio are respectively switched or swept to cyclically reduce the resonant response of multiple flexural natural modes of the duct structure. The study analytically shows, and confirms with simulations and experiments, that the vibration control produced by a simple “blind sweep” operation mode of the tuneable vibration absorber does not differ significantly from the (sub)optimal performance attainable via a switching operation mode.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.021
      Issue No: Vol. 93 (2018)
       
  • Design of interval observers and controls for PDEs using finite-element
           approximations
    • Authors: Tatiana Kharkovskaya; Denis Efimov; Andrey Polyakov; Jean-Pierre Richard
      Pages: 302 - 310
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Tatiana Kharkovskaya, Denis Efimov, Andrey Polyakov, Jean-Pierre Richard
      Synthesis of interval state estimators is investigated for the systems described by a class of parabolic Partial Differential Equations (PDEs). First, a finite-element approximation of a PDE is constructed and the design of an interval observer for the derived ordinary differential equation is given. Second, the interval inclusion of the state function of the PDE is calculated using the error estimates of the finite-element approximation. Finally, the obtained interval estimates are used to design a dynamic output stabilizing control. The results are illustrated by numerical experiments with an academic example and the Black–Scholes model of financial market.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.016
      Issue No: Vol. 93 (2018)
       
  • Stabilization of strictly dissipative discrete time systems with
           discounted optimal control
    • Authors: Vladimir Gaitsgory; Lars Grüne; Matthias Höger; Christopher M. Kellett; Steven R. Weller
      Pages: 311 - 320
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Vladimir Gaitsgory, Lars Grüne, Matthias Höger, Christopher M. Kellett, Steven R. Weller
      We consider stabilization of an equilibrium point via infinite horizon discounted optimal control in discrete-time. In addition to applications in economics and social sciences, discounted optimal control is a commonly used numerical technique guaranteeing solvability of certain classes of optimal control problems. In this paper, we present conditions based on strict dissipativity that ensure that the optimally controlled system is asymptotically stable or practically asymptotically stable. These conditions are shown to be complementary to recently proposed conditions based on a detectability property. Illustrative examples are provided.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.076
      Issue No: Vol. 93 (2018)
       
  • System identification using kernel-based regularization: New insights on
           stability and consistency issues
    • Authors: Gianluigi Pillonetto
      Pages: 321 - 332
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Gianluigi Pillonetto
      Learning from examples is one of the key problems in science and engineering. It deals with function reconstruction from a finite set of direct and noisy samples. Regularization in reproducing kernel Hilbert spaces (RKHSs) is widely used to solve this task and includes powerful estimators such as regularization networks. Recent achievements include the proof of the statistical consistency of these kernel-based approaches. Parallel to this, many different system identification techniques have been developed but the interaction with machine learning does not appear so strong yet. One reason is that the RKHSs usually employed in machine learning do not embed the information available on dynamic systems, e.g. BIBO stability. In addition, in system identification the independent data assumptions routinely adopted in machine learning are never satisfied in practice. This paper provides some new results which strengthen the connection between system identification and machine learning. Our starting point is the introduction of RKHSs of dynamic systems. They contain functionals over spaces defined by system inputs and allow to interpret system identification as learning from examples. In both linear and nonlinear settings, it is shown that this perspective permits to derive in a relatively simple way conditions on RKHS stability (i.e. the property of containing only BIBO stable systems or predictors), also facilitating the design of new kernels for system identification. Furthermore, we prove the convergence of the regularized estimator to the optimal predictor under conditions typical of dynamic systems.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.065
      Issue No: Vol. 93 (2018)
       
  • Adaptive Kalman filter for actuator fault diagnosis
    • Authors: Qinghua Zhang
      Pages: 333 - 342
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Qinghua Zhang
      An adaptive Kalman filter is proposed in this paper for actuator fault diagnosis in discrete time stochastic time varying systems. By modeling actuator faults as parameter changes, fault diagnosis is performed through joint state-parameter estimation in the considered stochastic framework. Under the classical uniform complete observability–controllability conditions and a persistent excitation condition, the exponential stability of the proposed adaptive Kalman filter is rigorously analyzed. In addition to the minimum variance property of the combined state and parameter estimation errors, it is shown that the parameter estimation within the proposed adaptive Kalman filter is equivalent to the recursive least squares algorithm formulated for a fictive regression problem. Numerical examples are presented to illustrate the performance of the proposed algorithm.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.075
      Issue No: Vol. 93 (2018)
       
  • Recursive nonlinear-system identification using latent variables
    • Authors: Per Mattsson; Dave Zachariah; Petre Stoica
      Pages: 343 - 351
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Per Mattsson, Dave Zachariah, Petre Stoica
      In this paper we develop a method for learning nonlinear system models with multiple outputs and inputs. We begin by modeling the errors of a nominal predictor of the system using a latent variable framework. Then using the maximum likelihood principle we derive a criterion for learning the model. The resulting optimization problem is tackled using a majorization–minimization approach. Finally, we develop a convex majorization technique and show that it enables a recursive identification method. The method learns parsimonious predictive models and is tested on both synthetic and real nonlinear systems.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.007
      Issue No: Vol. 93 (2018)
       
  • UDE-based robust boundary control for an unstable parabolic PDE with
           unknown input disturbance
    • Authors: Jiguo Dai; Beibei Ren
      Pages: 363 - 368
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Jiguo Dai, Beibei Ren
      A novel control strategy, named uncertainty and disturbance estimator (UDE)-based robust control, is applied to the stabilization of an unstable parabolic partial differential equation (PDE) with a Dirichlet type boundary actuator and an unknown time-varying input disturbance. The unstable PDE is stabilized by the backstepping approach, and the unknown input disturbance is compensated by the UDE, which constructs an estimation of the disturbance by filtering the system input and measurable state signals. The proposed UDE-based robust boundary control only requires the spectrum information of the disturbance signal and one boundary output measurement. Stability analysis of the closed-loop systems is carried out, and a numerical example is provided to validate the proposed method.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.080
      Issue No: Vol. 93 (2018)
       
  • Enforcement of opacity by public and private insertion functions
    • Authors: Yiding Ji; Yi-Chin Wu; Stéphane Lafortune
      Pages: 369 - 378
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Yiding Ji, Yi-Chin Wu, Stéphane Lafortune
      We study the enforcement of opacity, an information-flow security property, using insertion functions that insert fictitious events at the output of the system. The intruder is characterized as a passive external observer whose malicious goal is to infer system secrets from observed traces of system events. We consider the problems of enforcing opacity under the assumption that the intruder either knows or does not know the structure of the insertion function; we term this requirement as public–private enforceability. The case of private enforceability alone, where the intruder does not know the form of the insertion function, is solved in our prior work. In this paper, we address the stronger requirement of public–private enforceability, that requires opacity be preserved even if the intruder knows or discovers the structure of the insertion function. We formulate the concept of public–private enforceability by defining the notion of public safety. This leads to the notion of public–private enforcing (PP-enforcing) insertion functions. We then identify a necessary and sufficient condition for an insertion function to be PP-enforcing. We further show that if opacity is privately enforceable by the insertion mechanism, then it is also public–private enforceable. Using these results, we present a new algorithm to synthesize PP-enforcing insertion functions by a greedy-maximal strategy. This algorithm is the first of its kind to guarantee opacity when insertion functions are made public or discovered by the intruder.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.041
      Issue No: Vol. 93 (2018)
       
  • Reliable non-linear state estimation involving time uncertainties
    • Authors: Simon Rohou; Luc Jaulin; Lyudmila Mihaylova; Fabrice Le Bars; Sandor M. Veres
      Pages: 379 - 388
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Simon Rohou, Luc Jaulin, Lyudmila Mihaylova, Fabrice Le Bars, Sandor M. Veres
      This paper presents a new approach to bounded-error state estimation involving time uncertainties. For a given bounded observation of a continuous-time non-linear system, it is assumed that neither the values of the observed data nor their acquisition instants are known exactly. For systems described by state-space equations, we prove theoretically and demonstrate by simulations that the proposed constraint propagation approach enables the computation of bounding sets for the systems’ state vectors that are consistent with the uncertain measurements. The bounding property of the method is guaranteed even if the system is strongly non-linear. Compared with other existing constraint propagation approaches, the originality of the method stems from our definition and use of bounding tubes which enable to enclose the set of all feasible trajectories inside sets. This method makes it possible to build specific operators for the propagation of time uncertainties through the whole trajectory. The efficiency of the approach is illustrated on two examples: the dynamic localization of a mobile robot and the correction of a drifting clock.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.074
      Issue No: Vol. 93 (2018)
       
  • Higher order moment stability region for Markov jump systems based on
           cumulant generating function
    • Authors: Xiaoli Luan; Biao Huang; Fei Liu
      Pages: 389 - 396
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Xiaoli Luan, Biao Huang, Fei Liu
      This paper is concerned with the solution of higher order moment stability region for Markov jump systems with respect to cases of both known and unknown transition probabilities. By exploring the cumulant generating function, the original stochastic system with Markov jumping modes is transformed to a deterministic system. Then based on the estimation of matrix eigenvalues, the explicit solution for higher order moment stability region is expressed in terms of transition probabilities, operation modes, state transition matrix and its dimension, and the moment order. Several examples are presented to illustrate the effectiveness of the proposed method and its associated algorithm.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.032
      Issue No: Vol. 93 (2018)
       
  • Robustness of critical bit rates for practical stabilization of networked
           control systems
    • Authors: Adriano Da Silva; Christoph Kawan
      Pages: 397 - 406
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Adriano Da Silva, Christoph Kawan
      In this paper we address the question of robustness of critical bit rates for the stabilization of networked control systems over digital communication channels. For a deterministic nonlinear system, the smallest bit rate above which practical stabilization (in the sense of set-invariance) can be achieved is measured by the invariance entropy. Under the assumptions of chain controllability and uniform hyperbolicity on the set of interest, we prove that the invariance entropy varies continuously with respect to system parameters. Hence, in this case the critical bit rate is robust with respect to small perturbations.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.042
      Issue No: Vol. 93 (2018)
       
  • Scalable distributed model predictive control for constrained systems
    • Authors: Elham (Fatemeh) Asadi; Arthur Richards
      Pages: 407 - 414
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Elham (Fatemeh) Asadi, Arthur Richards
      A distributed model predictive control strategy is proposed for subsystems sharing a limited resource. Self-organized Time Division Multiple Access is used to coordinate subsystem controllers in a sequence such that no two re-optimize simultaneously. This new approach requires no central coordination or pre-organized optimizing sequence. The scheme guarantees satisfaction of coupled constraints despite dynamic entry and exit of subsystems.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.050
      Issue No: Vol. 93 (2018)
       
  • Speeding up finite-time consensus via minimal polynomial of a weighted
           graph — A numerical approach
    • Authors: Zheming Wang; Chong Jin Ong
      Pages: 415 - 421
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Zheming Wang, Chong Jin Ong
      This work proposes an approach to speed up finite-time consensus algorithm using the weights of a weighted Laplacian matrix. It is motivated by the need to reach consensus among states of a multi-agent system in a distributed control/optimization setting. The approach is an iterative procedure that finds a low-order minimal polynomial that is consistent with the topology of the underlying graph. In general, the lowest-order minimal polynomial achievable for a network system is an open research problem. This work proposes a numerical approach that searches for the lowest order minimal polynomial via a rank minimization problem using a two-step approach: the first being an optimization problem involving the nuclear norm and the second a correction step. Convergence of the algorithm is shown and effectiveness of the approach is demonstrated via several examples.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.067
      Issue No: Vol. 93 (2018)
       
  • The effects of linear and nonlinear characteristic parameters on the
           output frequency responses of nonlinear systems: The associated output
           frequency response function
    • Authors: Yunpeng Zhu; Z.Q. Lang
      Pages: 422 - 427
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Yunpeng Zhu, Z.Q. Lang
      In the present study, a new concept known as the Associated Output Frequency Response Function (AOFRF) is introduced to facilitate the analysis of the effects of both linear and nonlinear characteristic parameters on the output frequency responses of nonlinear systems. Based on the AOFRF concept, the study has shown, for the first time, that the output frequency responses of a wide class of nonlinear systems that are described by the NARX (Nonlinear Auto Regressive with eXogenous input) model can be represented by a polynomial function of both the system linear and nonlinear characteristic parameters of interests to the system analysis. Moreover, an efficient algorithm is derived to determine the structure and coefficients of the AOFRF based representation for system output frequency responses. Finally, a case study is provided to demonstrate the effectiveness and advantages of the new AOFRF based representation and the implication of the result to the analysis and design of nonlinear systems in the frequency domain.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.070
      Issue No: Vol. 93 (2018)
       
  • Riemannian optimal model reduction of linear port-Hamiltonian systems
    • Authors: Kazuhiro Sato
      Pages: 428 - 434
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Kazuhiro Sato
      In this paper, we describe the development of a Riemannian optimal model reduction method for linear stable port-Hamiltonian systems. This development is motivated by the fact that there remains room for improvement in existing methods. The model reduction problem is formulated as an optimization problem on the product manifold of the set of skew symmetric matrices, the manifold of the symmetric positive definite matrices, and Euclidean space. The reduced systems constructed using the optimal solutions to the problem preserve the original structure, i.e., stability, passivity, and the port-Hamiltonian form. The Riemannian gradient is derived to relate our problem to another problem in some studies, and the Hessian is also derived to solve our problem using a Riemannian trust region method. The initial point in the proposed method is chosen by using the output of the iterative rational Krylov algorithm for linear port-Hamiltonian systems (IRKA-PH). A numerical experiment illustrates that the proposed method considerably improves the results of IRKA-PH when the reduced-model dimension is small.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.051
      Issue No: Vol. 93 (2018)
       
  • Set-membership approach and Kalman observer based on zonotopes for
           discrete-time descriptor systems
    • Authors: Ye Wang; Vicenç Puig; Gabriela Cembrano
      Pages: 435 - 443
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Ye Wang, Vicenç Puig, Gabriela Cembrano
      This paper proposes a set-membership state estimator and a zonotopic Kalman observer for discrete-time descriptor systems. Both approaches are developed in a set-based context considering system disturbances, measurement noise, and unknown inputs. This set-membership state estimation approach determines the set of consistent states with the model and measurements by constructing a parameterized intersection zonotope. Two methods to minimize the size of this intersection zonotope are provided: one inspired by Kalman filtering and the other based on solving an optimization problem involving a series of linear matrix inequalities. Additionally, we propose a zonotopic Kalman observer for discrete-time descriptor systems. Moreover, the relationship between both approaches is discussed. In particular, it is proved that the zonotopic Kalman observer in the current estimation type is equivalent to the set-membership approach. Finally, a numerical example is used to illustrate and compare the effectiveness of the proposed approaches.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.082
      Issue No: Vol. 93 (2018)
       
  • Adaptive tracking control for nonlinear time-varying delay systems with
           full state constraints and unknown control coefficients
    • Authors: Dongjuan Li; Dapeng Li
      Pages: 444 - 453
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Dongjuan Li, Dapeng Li
      This paper proposes an adaptive tracking control approach for a class of nonlinear state-constrained and time-varying delay systems with unknown time-varying control coefficients. As far as we know, there is no control method for such systems at present. To stabilize such a class of systems, the neural networks and a backstepping technique are utilized to structure an adaptive tracking controller. The Nussbaum gain technique is utilized to solve the problem of unknown time-varying control coefficients, and the Lyapunov–Krasovskii functionals (LKFs) are employed to eliminate the effect of unknown time-varying delays. In addition, the states are guaranteed to remain within their constraint sets based on the Barrier Lyapunov functions (BLFs). Finally, it can be proved that all signals in the closed-loop systems are bounded, the state constraints are never violated and the tracking errors fluctuate within the predetermined compact range around the zero. The simulation results are provided to illustrate the effectiveness of the proposed control strategy.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.063
      Issue No: Vol. 93 (2018)
       
  • Stability and active power sharing in droop controlled inverter interfaced
           microgrids: Effect of clock mismatches
    • Authors: Ramachandra Rao Kolluri; Iven Mareels; Tansu Alpcan; Marcus Brazil; Julian de Hoog; Doreen Anne Thomas
      Pages: 469 - 475
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Ramachandra Rao Kolluri, Iven Mareels, Tansu Alpcan, Marcus Brazil, Julian de Hoog, Doreen Anne Thomas
      Stability and power sharing properties of droop controlled inverter-based microgrid systems depend on various design factors. Little explored is the effect of component mismatches and parameters drifts on the stability, steady state behaviour and power sharing properties of these systems. In this paper, the behaviour of frequency droop controlled inverter based microgrid systems in the presence of non-identical clocks is analysed. It is shown that power sharing between converters in a microgrid can be sensitive to clock mismatches. Our proposal shows that a coordination control that uses sparse inter-node communications is useful in ensuring desired active power sharing. Conditions are derived to ensure stability in the presence of the proposed controller and simulation results are presented.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.025
      Issue No: Vol. 93 (2018)
       
  • Guaranteed model-based fault detection in cyber–physical systems: A
           model invalidation approach
    • Authors: Farshad Harirchi; Necmiye Ozay
      Pages: 476 - 488
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Farshad Harirchi, Necmiye Ozay
      This paper presents a sound and complete fault detection approach for cyber–physical systems represented by hidden-mode switched affine models with time varying parametric uncertainty. The fault detection approach builds upon techniques from model invalidation. In particular, a set-membership approach is taken where the noisy input–output data is compared to the set of behaviors of a nominal model. As we show, this set-membership check can be reduced to the feasibility of a mixed-integer linear programming (MILP) problem, which can be solved efficiently by leveraging the state-of-the-art MILP solvers. In the second part of the paper, given a system model and a fault model, the concept of T -detectability is introduced. If a pair of system and fault models satisfies T -detectability property for a finite T , this allows the model invalidation algorithm to be implemented in a receding horizon manner, without compromising detection guarantees. In addition, the concept of weak-detectability is introduced which extends the proposed approach to a more expressive class of fault models that capture language constraints on the mode sequences. Finally, the efficiency of the approach is illustrated with numerical examples motivated by smart building radiant systems.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.040
      Issue No: Vol. 93 (2018)
       
  • Distributed extremum-seeking control over networks of dynamically coupled
           unstable dynamic agents
    • Authors: Martin Guay; Isaac Vandermeulen; Sean Dougherty; P. James McLellan
      Pages: 498 - 509
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Martin Guay, Isaac Vandermeulen, Sean Dougherty, P. James McLellan
      In this paper, a distributed extremum seeking control technique is proposed to solve a class of real-time optimization problems over a network of dynamic agents with unknown unstable dynamics. Each dynamic agent measures a cost that is shared over a network. A dynamic average consensus approach is used to provide each agent with an estimate of the total network cost. The extremum seeking controller operates at each agent to allow each agent to contribute to the optimization of the total cost, in a cooperative fashion. The extremum seeking control technique is based on a proportional–integral approach that provides improvements in transient performance over standard techniques. The contribution of the proposed technique is to solve the simultaneous stabilization and real-time optimization. A dynamic network simulation example is presented to demonstrate the effectiveness of the technique.

      PubDate: 2018-04-15T06:25:52Z
      DOI: 10.1016/j.automatica.2018.03.081
      Issue No: Vol. 93 (2018)
       
  • Complexity of deciding detectability in discrete event systems
    • Authors: Masopust
      Abstract: Publication date: July 2018
      Source:Automatica, Volume 93
      Author(s): Tomáš Masopust
      Detectability of discrete event systems (DESs) is a question whether the current and subsequent states can be determined based on observations. Shu and Lin designed a polynomial-time algorithm to check strong (periodic) detectability and an exponential-time (polynomial-space) algorithm to check weak (periodic) detectability. Zhang showed that checking weak (periodic) detectability is PSpace-complete. This intractable complexity opens a question whether there are structurally simpler DESs for which the problem is tractable. In this paper, we show that it is not the case by considering DESs represented as deterministic finite automata without non-trivial cycles, which are structurally the simplest deadlock-free DESs. We show that even for such very simple DESs, checking weak (periodic) detectability remains intractable. On the contrary, we show that strong (periodic) detectability of DESs can be efficiently verified on a parallel computer.

      PubDate: 2018-04-15T06:25:52Z
       
 
 
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