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  • 1. Bemporad, Alberto
    et al.
    Di Cairano, Stefano
    Henriksson, Erik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Hybrid model predictive control based on wireless sensor feedback: An experimental study2010In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 20, no 2, p. 209-225Article in journal (Refereed)
    Abstract [en]

    Design and experimental validation of model predictive control (MPC) of a hybrid dynamical laboratory process with wireless sensors is presented. The laboratory process consists of four infrared lamps, controlled in pairs by two on/off switches, and of a transport belt, where moving parts equipped with wireless sensors are heated by the lamps. The process, which is motivated by heating processes in the plastic and printing industry, presents interesting hybrid dynamics. By approximating the stationary heat spatial distribution as a piecewise affine function of the position along the belt, the resulting plant model is a hybrid dynamical system. The control architecture is based on the reference governor approach: the process is actuated by a local controller, while a hybrid MPC algorithm running on a remote base station sends optimal belt velocity setpoints and lamp on/off commands over a wireless link, exploiting the sensor information received through the wireless network. A discrete-time hybrid model of the process is used for the hybrid MPC algorithm and for the state estimator. The physical modelling of the process and the hybrid MPC algorithm are presented in detail, together with the hardware and software architectures. The experimental results show that the presented theoretical framework is well suited for control of the new laboratory process, and that the process can be used as a prototype system for evaluating hybrid and networked control strategies.

  • 2.
    Briat, Corentin
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Robust stability and stabilization of uncertain linear positive systems via integral linear constraints: L-1-gain and L-infinity-gain characterization2013In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 23, no 17, p. 1932-1954Article in journal (Refereed)
    Abstract [en]

    Copositive linear Lyapunov functions are used along with dissipativity theory for stability analysis and control of uncertain linear positive systems. Unlike usual results on linear systems, linear supply rates are employed here for robustness and performance analysis using L-1-gain and L-gain. Robust stability analysis is performed using integral linear constraints for which several classes of uncertainties are discussed. The approach is then extended to robust stabilization and performance optimization. The obtained results are expressed in terms of robust linear programming problems that are equivalently turned into finite dimensional ones using Handelman's theorem. Several examples are provided for illustration.

  • 3. Byrnes, Christopher I.
    et al.
    Lindquist, Anders
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Interior point solutions of variational problems and global inverse function theorems2007In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 17, no 5-6, p. 463-481Article in journal (Refereed)
    Abstract [en]

    Variational problems and the solvability of certain nonlinear equations have a long and rich history beginning with calculus and extending through the calculus of variations. In this paper, we are interested in 'well-connected' pairs of such problems which are not necessarily related by critical point considerations. We also study constrained problems of the kind which arise in mathematical programming. We are also interested in interior minimizing points for the variational problem and in the well-posedness (in the sense of Hadamard) of solvability of the related systems of equations. We first prove a general result which implies the existence of interior points and which also leads to the development of certain generalization of the Hadamard-type global inverse function theorem, along the theme that uniqueness quite often implies existence. This result is illustrated by proving the non-existence of shock waves for certain initial data for the vector Burgers' equation. The global inverse function theorem is also illustrated by a derivation of the existence of positive definite solutions of matrix Riccati equations without first analysing the nonlinear matrix Riccati differential equation. The main results on the existence of solutions to geometrically constrained well-connected pairs are then presented and illustrated by a geometric analysis of the existence of interior points for linear programming problems.

  • 4. Dai, L.
    et al.
    Xia, Y.
    Gao, Yulong
    KTH, School of Electrical Engineering and Computer Science (EECS), Centres, ACCESS Linnaeus Centre.
    Cannon, M.
    Distributed stochastic MPC for systems with parameter uncertainty and disturbances2018In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 28, no 6, p. 2424-2441Article in journal (Refereed)
    Abstract [en]

    A distributed stochastic model predictive control algorithm is proposed for multiple linear subsystems with both parameter uncertainty and stochastic disturbances, which are coupled via probabilistic constraints. To handle the probabilistic constraints, the system dynamics is first decomposed into a nominal part and an uncertain part. The uncertain part is further divided into 2 parts: the first one is constrained to lie in probabilistic tubes that are calculated offline through the use of the probabilistic information on disturbances, whereas the second one is constrained to lie in polytopic tubes whose volumes are optimized online and whose facets' orientations are determined offline. By permitting a single subsystem to optimize at each time step, the probabilistic constraints are then reduced into a set of linear deterministic constraints, and the online optimization problem is transformed into a convex optimization problem that can be performed efficiently. Furthermore, compared to a centralized control scheme, the distributed stochastic model predictive control algorithm only requires message transmissions when a subsystem is optimized, thereby offering greater flexibility in communication. By designing a tailored invariant terminal set for each subsystem, the proposed algorithm can achieve recursive feasibility, which, in turn, ensures closed-loop stability of the entire system. A numerical example is given to illustrate the efficacy of the algorithm. Copyright 

  • 5.
    Dankowicz, Harry
    et al.
    Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign.
    Svahn, Fredrik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    On the stabilizability of near-grazing dynamics in impact oscillators2007In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 17, no 15, p. 1405-1429Article in journal (Refereed)
    Abstract [en]

    A constructive proof is presented for the existence of event-driven control strategies that guarantee the local persistence of system attractors with at most low-velocity contact in vibro-impacting oscillators. In particular, sufficient conditions are formulated on the linearization of the control strategies along a grazing periodic trajectory, i.e. an oscillating motion that achieves zero-relative-velocity contact with a mechanical obstacle, to ensure the asymptotic stability of the grazing trajectory and, consequently, sustained dynamics in the vicinity of the grazing trajectory even under small changes in system parameters. The implications of the methodology are illustrated with linear and nonlinear, single- and multiple-degree-of-freedom examples of vibro-impact oscillators.

  • 6.
    Di Benedetto, Maria Domenica
    et al.
    Univ Aquila, Coll Engn, Ctr Excellence DEWS, I-67100 Laquila, Italy..
    Johansson, Karl H.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Santucci, Fortunato
    Univ Aquila, Coll Engn, Ctr Excellence DEWS, I-67100 Laquila, Italy..
    Industrial control over wireless networks2010In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 20, no 2, p. 119-122Article in journal (Other academic)
  • 7. Dong, Yi
    et al.
    Xu, Shengyuan
    Hu, Xiaoming
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Coordinated control with multiple dynamic leaders for uncertain Lagrangian systems via self-tuning adaptive distributed observer2017In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 27, no 16, p. 2708-2721Article in journal (Refereed)
    Abstract [en]

    This paper studies coordinated control of multiple Lagrangian systems with parametric uncertainties subject to external disturbances by proposing a fully distributed continuous control law based on the improved self-tuning adaptive observer inspired by non-identifier-based high-gain adaptive control technique. Under this distributed continuous control law, a group of Lagrangian systems are driven to the convex hull spanned by multiple heterogenous dynamic leaders, which can be any combination of step signals of arbitrary unknown magnitudes, ramp signals of arbitrary unknown slopes, and sinusoidal signals of arbitrary unknown amplitudes, initial phases, and any unknown frequencies. It is also worth to mention that this control law we propose, depending neither on any information of leader systems for uninformed followers, nor on external disturbances, even independent of neighbors' velocity, can achieve asymptotic tracking of multiple leaders without any additional condition instead of ensuring the ultimate boundedness of the containment error as in the literature.

  • 8.
    Jacobsen, Elling W.
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Trané, Camilla
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Using dynamic perturbations to identify fragilities in biochemical networks2010In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 20, no 9, p. 1027-1046Article in journal (Refereed)
    Abstract [en]

    Biological functions at the cellular level result from interactions between genes, proteins and metabolites within complex biochemical reaction networks. Identifying specific and localized fragilities in such networks is important to understand the source of biological malfunctions, and to devise strategies for fighting disease states that have developed robustness. Herein we consider a method based on robust control theoretic concepts for identifying network fragilities. In particular, we consider adding static or dynamic perturbations to the network edges, i.e. the direct binary interactions within the network, and compute the smallest perturbation that induces a bifurcation, and hence a qualitative change, in the network function. The proposed method can also serve as a powerful modeling tool in that it can be used to identify parts of a model that require more detailed descriptions of the underlying processes. The method is demonstrated by application to models of sustained oscillations in the glycolytic pathway and bistability in the mitogen-activated protein kinase (MAPK) signal transduction.

  • 9.
    Jafarian, Matin
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Robust consensus of unicycles using ternary and hybrid controllers2017In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 27, no 17, p. 4013-4034Article in journal (Refereed)
    Abstract [en]

    This paper presents consensus of the orientations and average positions for a group of unicycles using ternary and hybrid controllers. The decentralized controllers designed to reach consensus of the average positions take only values in the set {-1; 0; +1}. In addition, a hybrid controller is introduced to control the orientations. Finite-time practical consensus of the average positions is proven despite the simple ternary control laws together with asymptotic consensus of the orientations. Furthermore, the consensus problem is studied in the presence of matched input disturbances that are locally rejected using an internal-model-based controller. The analysis is performed in a hybrid framework. Simulation results illustrate the effectiveness of the design.

  • 10.
    Jönsson, Ulf T.
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Robustness of transitions in switched linear systems2005In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 15, no 7, p. 293-314Article in journal (Refereed)
    Abstract [en]

    A robustness problem for transitions in switched linear systems is considered in this paper. The specific problem is to estimate the size of the image when a subset of an affine subspace is mapped by an uncertain system to another affine subspace. It is assumed that the system dynamics is linear and that the uncertainty and the disturbances are characterized by integral quadratic constraints (IQC). The estimates can be obtained by solving a special affinely parameterized linear quadratic optimal control problem. The results are applied to the problem of verifying robustness of oscillations in a switched linear system. In particular, sufficient conditions are given, which ensure that there remains a periodic solution when the system is perturbed by a Lipschitz continuous nonlinearity.

  • 11.
    Liu, Kun
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Fridman, Emilia
    Tel Aviv University.
    Discrete-time Network-based Control under Schedulings and Actuator Constraints2014In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239Article in journal (Other academic)
    Abstract [en]

    This paper is concerned with the solution bounds for discrete-time networked control systems via delay-dependent Lyapunov-Krasovskii methods.Solution bounds are widely used for systems with input saturation caused byactuator saturation or by the quantizers with saturation.The time-delay approach has been introduced recently for the stabilization of continuous-time networked control systems under the Round-Robin protocol in \cite{KunSCL12} and under a weighted Try-Once-Discard protocol in \cite{KunCDC12}, respectively.Actuator saturation has not been taken into account in \cite{KunCDC12} and \cite{KunSCL12}.In the present paper, for the first time the time-delay approach is extended to the stability analysis of the discrete-time networked control systems under both scheduling protocols and actuators saturation. The communication delays are allowed tobe larger than the sampling intervals.A novel Lyapunov-based method is presented for finding the domain of attraction.Polytopic uncertainties in the system model can be easily included in our analysis. The efficiency of the time-delay approach is illustrated on the example of a cart-pendulum system.

  • 12. Long, Yushen
    et al.
    Liu, Shuai
    Xie, Lihua
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Distributed nonlinear model predictive control based on contraction theory2018In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 28, no 2, p. 492-503Article in journal (Refereed)
    Abstract [en]

    A novel distributed model predictive control algorithm for continuous-time nonlinear systems is proposed in this paper. Contraction theory is used to estimate the prediction error in the algorithm, leading to new feasibility and stability conditions. Compared to existing analysis based on Lipschitz continuity, the proposed approach gives a distributed model predictive control algorithm under less conservative conditions, allowing stronger couplings between subsystems and a larger sampling interval when the subsystems satisfy the specified contraction conditions. A numerical example is given to illustrate the effectiveness and advantage of the proposed approach.

  • 13.
    Meng, Ziyang
    et al.
    KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre. Shanghai Jiao Tong University, China.
    Lin, Zongli
    On distributed finite-time observer design and finite-time coordinated tracking of multiple double integrator systems via local interactions2014In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 24, no 16, p. 2473-2489Article in journal (Refereed)
    Abstract [en]

    This paper studies finite-time coordinated tracking problem for multiple double integrator systems with a time-varying leader's velocity and bounded external disturbances. We consider the dynamic feedback designs for two different cases. In the first case, the velocities of the followers and the leader are assumed to be unavailable, and the communication topology is assumed to be undirected and fixed. In the second case, the velocities of the followers and the leader are assumed to be available, and the communication topology is assumed to be directed and switching. Distributed finite-time observers are designed, respectively, to obtain the velocity information in the first case and the relative state information in the second case. The states of these observers are then used to design control inputs that achieve finite time robust coordinated tracking of multiple double integrator systems in the presence of bounded disturbances for these two cases. Simulation results are provided to validate the effectiveness of these theoretical results.

  • 14.
    Rabi, Maben
    et al.
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Stabellini, Luca
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Proutiere, Alexandre
    Johansson, Mikael
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Networked estimation under contention-based medium access2010In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 20, no 2, p. 140-155Article in journal (Refereed)
    Abstract [en]

    This paper studies networked estimation over a communication channel shared by a contention-based medium access protocol. A collection of N identical and physically decoupled scalar systems are sampled without sensor noise and transmitted over a common channel, using a contention-based medium access mechanism. We first carry out a calculation of the average distortion in estimation with irregular samples. Given the rate of packet generation at sensors, we characterize the traffic characteristics of the some contention-based MAC schemes. This lets us derive the statistics of inter-arrival times which in turn allows us to compute the packet loss rates and also the statistics of delay within a sample period. Using these results, we track the estimation performance as the sample generation rate and the number of contending nodes are varied. We provide a heuristic rule-of-thumb for choosing the sampling interval which minimizes the average distortion. By combining the network traffic characterization with that of the estimation performance, we show this rule performs pretty well. Carrying along the same lines, we are able to compute the scaling limits of estimation performance with respect to the number of contending nodes.

  • 15.
    Ren, Wei
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Xiong, Junlin
    Univ Sci & Technol China, Dept Automat, Hefei, Peoples R China..
    Razumikhin stability theorems for a general class of stochastic impulsive switched time-delay systems2019In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 29, no 12, p. 3988-4001Article in journal (Refereed)
    Abstract [en]

    This paper studies stability of a general class of impulsive switched systems under time delays and random disturbances using multiple Lyapunov functions and fixed dwell-time. In the studied system model, the impulses and switches are allowed to occur asynchronously. As a result, the switching may occur in the impulsive intervals and the impulses can occur in the switching intervals, which have great effects on system stability. Since the switches do not bring about the change of the system state, we study two cases in terms of the impulses, ie, the stable continuous dynamics case and the stable impulsive dynamics case. According to multiple Lyapunov-Razumikhin functions and the fixed dwell-time, Razumikhin-type stability conditions are established. Finally, the obtained results are illustrated via a numerical example from the synchronization problem of chaotic systems.

  • 16. Sandberg, Henrik
    et al.
    Lanzon, Alexander
    Anderson, Brian D. O.
    Model approximation using magnitude and phase criteria: Implications for model reduction and system identification2007In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 17, no 05-6, p. 435-461Article in journal (Refereed)
    Abstract [en]

    In this paper, we use convex optimization for model reduction and identification of transfer functions. Two different approximation criteria are studied. When the first criterion is used, magnitude functions are matched, and when the second criterion is used, phase functions are matched. The weighted error bounds have direct interpretation in a Bode diagram, and are suitable to engineers working with frequency-domain data. We also show that transfer functions that have similar magnitude or phase functions have a small relative H-infinity error, under certain stability and minimum phase assumptions. The error bounds come from bounds associated with the Hilbert transform operator restricted in its application to rational transfer functions. Furthermore, it is shown how the approximation procedures can be implemented with linear matrix inequalities, and four examples are included to illustrate the results.

  • 17.
    Segundo Sevilla, Felix Rafael
    et al.
    Department of Electrical and Electronic Engineering, Imperial College London, London, UK.
    Jaimoukha, Imad
    Imperial College London.
    Chaudhuri, Balarko
    Imperial College London.
    Korba, Petr
    Zurich University of Applied Sciences.
    Fault-tolerant control design to enhance damping of inter-area oscillations in power grids2013In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 24, no 8-9, p. 1304-1316Article in journal (Refereed)
    Abstract [en]

    In this paper, passive and active approaches for the design of fault-tolerant controllers (FTCs) are presented. The FTCs are used to improve the damping of inter-area oscillations in a power grid. The effectiveness of using a combination of local and remote (wide area) feedback signals is first demonstrated. The challenge is then to guarantee a minimum level of dynamic performance following a loss of remote signals. The designs are based on regional pole placement using linear matrix inequalities. First, a passive FTC is proposed. It is shown that the computation of the controller reduces to the solution of bilinear matrix inequalities. An iterative procedure is then used to design the controller. Next, as an alternative to active, time-varying controllers, one for each fault scenario, we propose an approach for the design of a ‘minimal switching’ FTC in which only one controller is designed, but where a simple switch is incorporated into the controller structure. A case study in a linear and nonlinear Nordic equivalent system is presented to show that the closed-loop response using a conventional control design could deteriorate the performance or even destabilize the system if the remote signals are lost and to demonstrate the effectiveness of the proposed FTC designs.

  • 18.
    Song, Wenjun
    et al.
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Tang, Y.
    Hong, Y.
    Hu, Xiaoming
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Relative attitude formation control of multi-agent systems2017In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 27, no 18, p. 4457-4477Article in journal (Refereed)
    Abstract [en]

    This paper investigates the relative attitude formation control problem for a group of rigid-body agents using relative attitude information on SO(3). On the basis of the gradient of a potential function, a family of distributed angular velocity control laws, which differ in the sense of a geodesic distance dependent function, is proposed. With directed and switching interaction topologies, the desired relative attitude formation is showed to be achieved asymptotically provided that the topology is jointly quasi-strongly connected. Moreover, several sufficient conditions for the desired formation to be achieved exponentially and almost globally are given. Additionally, numerical examples are provided to illustrate the effectiveness of the proposed distributed control laws.

  • 19. Wang, Lin
    et al.
    Wang, Xiaofan
    Hu, Xiaoming
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Connectivity maintenance and distributed tracking for double-integrator agents with bounded potential functions2015In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 25, no 4, p. 542-558Article in journal (Refereed)
    Abstract [en]

    In this paper, we develop a set of decentralized control laws with bounded potential functions. The basic control law is a combination of attractive, repulsive, and alignment forces, which can keep connectivity, avoid collision, synchronize all agents, and further track a constant moving leader. Furthermore, we investigate the distributed tracking problem with a varying-velocity leader, where the acceleration of the leader can not be measured. Two cases are considered; the acceleration of the leader is bounded, and the acceleration function satisfies Lipschitz condition. In the first case, the relative velocities of neighbors are integrated and transmitted as a new variable to account for the uncertain time-varying acceleration. In the second case, two distributed estimators are added for the leader's position and velocity. Finally, some simulations are presented to show the effectiveness of the proposed algorithms.

  • 20. Wang, Xu
    et al.
    Saberi, Ali
    Stoorvogel, Anton A.
    Grip, Havard Fjaer
    Yang, Tao
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Synchronization in a network of identical discrete-time agents with uniform constant communication delay2014In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 24, no 18, p. 3076-3091Article in journal (Refereed)
    Abstract [en]

    This paper studies the synchronization problem for a network of identical discrete-time agents with unknown uniform constant communication delay. When the agents are non-introspective, the problem is solvable via a decentralized low-gain-based synchronization controller if the delay satisfies the proposed upper bound. When the agents are introspective, the synchronization problem can be solved with arbitrary bounded communication delay.

  • 21. Wang, Xu
    et al.
    Saberi, Ali
    Yang, Tao
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Synchronization in heterogeneous networks of discrete-time introspective right-invertible agents2014In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 24, no 18, p. 3255-3281Article in journal (Refereed)
    Abstract [en]

    This paper studies output synchronization problem, formation problem, and regulated synchronization problem for a heterogenous network of discrete-time introspective right-invertible agents. We first propose a decentralized control scheme to solve the output synchronization problem for a set of communication topologies. Moreover, if the synchronization trajectories are assumed to be bounded, a universal controller can be constructed for all communication topologies, which contain a directed spanning tree. The design can be applied to solve the formation problem with arbitrary formation vectors. In the regulated synchronization problem, we assume only the root receives information from exosystem. We then design a decentralized controller to solve the problem for a set of communication topologies.

  • 22. Witrant, E.
    et al.
    D'Innocenzo, A.
    Sandou, G.
    Santucci, F.
    Di Benedetto, M. D.
    Isaksson, A. J.
    Johansson, Karl Henrik
    KTH, School of Electrical Engineering (EES), Automatic Control. KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
    Niculescu, S-I
    Olaru, S.
    Serra, E.
    Tennina, S.
    Tiberi, U.
    Wireless ventilation control for large-scale systems: The mining industrial case2010In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 20, no 2, p. 226-251Article in journal (Refereed)
    Abstract [en]

    This paper describes a new industrial case on automation, for large-scale systems with high environmental impact: the mining ventilation control systems. Ventilation control is essential for the operation of a mine in terms of safety (CO and NO, regulation) and energy optimization. We first discuss a novel regulation architecture, highlighting the interest for a model-based control approach and the use of distributed sensing capabilities thanks to a wireless sensor network (WSN). We propose a new model for underground ventilation. The main components of the system dynamics are described with time-delays, transmission errors, energy losses and concentration profiles. Two different model-based control approaches, which can embody the complex dynamics of the system, are proposed. The first one resorts to a nonlinear model predictive control strategy (receding horizon) and aims to energy minimization, thanks to a continuous operation of the fans. The second one, based on a hybrid description of the model and fans operation, provides automatic verification of the wireless control thanks to abstraction techniques. These control strategies are compared with simulations, in terms of regulation efficiency, energy consumption and the need for computational capabilities. The industrial case description and control strategies open new vistas for the development of global system approaches that allow for the optimization of energy consumption of complex large-scale systems.

  • 23. Xiang, F. L.
    et al.
    Wikander, Jan
    KTH, Superseded Departments, Machine Design.
    QFT control design for an approximately linearized pneumatic positioning system2003In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 13, no 7, p. 675-688Article in journal (Refereed)
    Abstract [en]

    A block-oriented approximate feedback linearization for control of a pneumatic cylinder positioning system is introduced and a rather detailed discussion is presented on the uncertain linearization residual characterization. It is shown that making use of the characterized gain-phase information of the linearized system leads to a more reasonable trade-off between performance and stability in the QFT control design and thus results in high control performance. Simulation and experimental results are shown.

  • 24.
    Yang, Tao
    et al.
    Washington State Univ., USA.
    Saberi, Ali
    Stoorvogel, Anton A.
    Grip, Havard Fjaer
    Output synchronization for heterogeneous networks of introspective right-invertible agents2014In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 24, no 13, p. 1821-1844Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the output synchronization problem for heterogeneous networks of right-invertible linear agents. We assume that all the agents are introspective, meaning that they have access to their own local measurements. Under this assumption, we then propose a decentralized control scheme for solving the output synchronization problem for a set of network topologies. The proposed scheme can also be applied to solve the output formation problem with arbitrary formation vectors. We also consider the regulation of output synchronization problem, where the output of each agent has to track an a priori specified reference trajectory, generated by an exosystem. In this case, we assume that the root agent has access to its own output relative to the reference trajectory.

  • 25.
    Yang, Tao
    et al.
    Washington State University .
    Stoorvogel, Anton A.
    Grip, Havard Fjaer
    Saberi, Ali
    Semi-global regulation of output synchronization for heterogeneous networks of non-introspective, invertible agents subject to actuator saturation2014In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 24, no 3, p. 548-566Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the semi-global regulation of output synchronization problem for heterogeneous networks of invertible linear agents subject to actuator saturation. That is, we regulate the output of each agent according to an a priori specified reference model. The network communication infrastructure provides each agent with a linear combination of its own output relative to that of neighboring agents, and it allows the agents to exchange information about their own internal observer estimates while some agents have access to their own outputs relative to the reference trajectory.

  • 26. Zhang, J.
    et al.
    Johansson, Karl H.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Lygeros, J.
    Sastry, S.
    Zeno hybrid systems2001In: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 11, no 5, p. 435-451Article in journal (Refereed)
1 - 26 of 26
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