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2. Supervisory Control of Fair Discrete-Event Systems: A Canonical Temporal Logic Foundation.
- Subjects
SUPERVISORY control systems ,LOGIC ,CONTROLLABILITY in systems engineering ,TASK analysis - Abstract
This paper studies the linear-time temporal logic (LTL) control of a class of fair discrete-event systems (DESs). It is motivated by the curious extent in which the use of LTL can be strengthened and differentiated in control theory development. Over a fair DES model, a marker-progressive supervisory control problem is formulated in LTL. The problem formulation admits a more flexible specification of multiple markers to distinguish different DES tasks, and seeks to find a supervisor—a passive control function by convention for specified temporal safety—such that a fair DES under its control is guaranteed to make constant progress to these markers. The problem is studied in terms of DES marker-controllability—a new controllability concept formulation of temporal safety for constant marker progress. This new formulation sheds light on how event fairness in DESs coachieves such marker progress with supervision that exists. It is shown that a solution supervisor may be found by canonical LTL verification. Three examples are provided for illustration. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. Linear Tracking MPC for Nonlinear Systems—Part I: The Model-Based Case.
- Author
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Berberich, Julian, Kohler, Johannes, Muller, Matthias A., and Allgower, Frank
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NONLINEAR systems ,NONLINEAR dynamical systems ,PREDICTIVE control systems ,ONLINE education ,LINEAR control systems - Abstract
In this article, we develop a tracking model predictive control (MPC) scheme for nonlinear systems using the linearized dynamics at the current state as a prediction model. Under reasonable assumptions on the linearized dynamics, we prove that the proposed MPC scheme exponentially stabilizes the optimal reachable equilibrium w.r.t. a desired target setpoint. Our theoretical results rely on the fact that, close to the steady-state manifold, the prediction error of the linearization is small, and hence, we can slide along the steady-state manifold toward the optimal reachable equilibrium. The closed-loop stability properties mainly depend on a cost matrix, which allows us to trade off performance, robustness, and the size of the region of attraction. In an application to a nonlinear continuous stirred tank reactor, we show that the scheme, which only requires solving a convex quadratic program online, has comparable performance to a nonlinear MPC scheme while being computationally significantly more efficient. Furthermore, our results provide the basis for controlling nonlinear systems based on data-dependent linear prediction models, which we explore in our companion paper. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. Informational Cascades With Nonmyopic Agents.
- Author
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Bistritz, Ilai, Heydaribeni, Nasimeh, and Anastasopoulos, Achilleas
- Subjects
INFORMATION storage & retrieval systems ,PRODUCT quality ,EQUILIBRIUM - Abstract
We consider an environmentwhere players need to decide whether to buy a certain product (or adopt a technology) or not. The product is either good or bad, but its true value is unknown to the players. Instead, each player has her own private information on its quality. Each player can observe the previous actions of other players and estimate the quality of the product. A classic result in the literature shows that in similar settings, informational cascades occur, where learning stops for the whole network and players repeat the actions of their predecessors. In contrast to this literature, in this paper, players get more than one opportunity to act. In each turn, a player is chosen uniformly at random from all the players and can decide to buy the product and leave the market or wait. Her utility is the total expected discounted reward, and thus, myopic strategies may not constitute equilibria. We provide a characterization of perfect Bayesian equilibria (PBEs) with forward-looking strategies through a fixed-point equation of dimensionality that grows only quadratically with the number of players. Using this tractable fixed-point equation, we show the existence of a PBE and characterize PBEs with threshold strategies. Based on this characterization, we study informational cascades in two regimes. First, we show that for a discount factor $\delta$ strictly smaller than 1, informational cascades happen with high probability as the number of players $N$ increases. Furthermore, only a small portion of the total information in the system is revealed before a cascade occurs. Second, and more surprisingly, we show that for a fixed $N$ , and for a sufficiently large $\delta < 1$ , when the product is bad, there exists an equilibrium where an informational cascade can happen only after at least half of the players revealed their private information, and consequently, the probability for a “bad cascade” where all the players buy the product vanishes exponentially with $N$. Finally, when $\delta =1$ and the product is bad, there exists an equilibrium where informational cascades do not happen at all. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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5. Correction to “A Framework for Control System Design Subject to Average Data-Rate Constraints”.
- Author
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Derpich, Milan S. and Ostergaard, Jan
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SYSTEMS design ,DISTRIBUTION (Probability theory) ,STOCHASTIC processes ,STOCHASTIC systems ,CHANNEL coding ,TIME measurements - Abstract
Theorem 4.1 in the 2011 paper “A Framework for Control System Design Subject to Average Data-Rate Constraints” allows one to lower bound average operational data rates in feedback loops (including the situation in which encoder and decoder have side information). Unfortunately, its proof is invalid. In this note, we first state the theorem and explain why its proof is flawed, and then provide a correct proof under weaker assumptions. [ABSTRACT FROM AUTHOR]
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- 2022
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6. IEEE Control Systems Society Information.
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INFORMATION society ,INFORMATION storage & retrieval systems ,STRATEGIC planning ,SLIDING mode control ,ELECTRONIC publications ,DISTRIBUTED parameter systems - Published
- 2022
- Full Text
- View/download PDF
7. IEEE Control Systems Society Information.
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INFORMATION society ,INFORMATION storage & retrieval systems ,EDITORIAL boards - Abstract
Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication. [ABSTRACT FROM AUTHOR]
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- 2022
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- View/download PDF
8. IEEE Control Systems Society Information.
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INFORMATION society ,INFORMATION storage & retrieval systems ,EDITORIAL boards - Abstract
Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication. [ABSTRACT FROM AUTHOR]
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- 2022
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9. A Local Direct Method for Module Identification in Dynamic Networks With Correlated Noise.
- Author
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Ramaswamy, Karthik Raghavan and Hof, Paul M. J. Van den
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NOISE ,CONFOUNDING variables ,PARAMETER identification ,MISO - Abstract
The identification of local modules in dynamic networks with known topology has recently been addressed by formulating conditions for arriving at consistent estimates of the module dynamics, under the assumption of having disturbances that are uncorrelated over the different nodes. The conditions typically reflect the selection of a set of node signals that are taken as predictor inputs in an multiple-input-single-output (MISO) identification setup. In this paper an extension is made to arrive at an identification setup for the situation that process noises on the different node signals can be correlated with each other. In this situation the local module may need to be embedded in an multiple-input--multiple-output (MIMO) identification setup for arriving at a consistent estimate with maximum likelihood properties. This requires the proper treatment of confounding variables. The result is a set of algorithms that, based on the given network topology and disturbance correlation structure, selects an appropriate set of node signals as predictor inputs and outputs in an MISO or MIMO identification setup. Three algorithms are presented that differ in their approach of selecting measured node signals. Either a maximum or a minimum number of measured node signals can be considered, as well as a preselected set of measured nodes. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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10. Comments on “Tracking Performance Guarantees in the Presence of Quantization for Uncertain Nonlinear Systems”.
- Author
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Huang, Xiucai and Song, Yongduan
- Subjects
UNCERTAIN systems ,NONLINEAR systems ,ARTIFICIAL satellite tracking ,MASTS & rigging ,DYNAMIC positioning systems - Abstract
In this article, we first show that the main results claimed in the paper by Bikas and Rovithakis (2021) involve some errors as the selection conditions for the design parameters are not sufficient to ensure the boundedness of all the closed-loop signals, then we provide the corresponding corrections under the same controller, so that the underlying quantized control problem can be tackled. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
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11. IEEE Control Systems Society.
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STRATEGIC planning ,ELECTRONIC publications ,DISTRIBUTED parameter systems ,DISCRETE systems - Abstract
The article lists the Institute of Electrical and Electronics Engineers Control Systems Society's Board of Governors and presents information for the authors.
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- 2022
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12. Erratum to “A Contraction Approach to the Hierarchical Analysis and Design of Networked Systems”.
- Author
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Russo, Giovanni, Bernardo, Mario di, and Sontag, Eduardo D.
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INFORMATION & communication technologies - Abstract
A small correction is made in the example of Section V (A representative application to networked systems) of the paper with the above title. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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13. IEEE Control Systems Society.
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STRATEGIC planning ,ELECTRONIC publications ,DISTRIBUTED parameter systems ,DISCRETE systems - Published
- 2022
- Full Text
- View/download PDF
14. IEEE Control Systems Society.
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EDITORIAL boards - Abstract
Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
- View/download PDF
15. IEEE Control Systems Society.
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COMMITTEES - Abstract
Provides a listing of current committee members and society officers. [ABSTRACT FROM AUTHOR]
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- 2022
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- View/download PDF
16. IEEE Control Systems Society.
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STRATEGIC planning ,ELECTRONIC publications ,DISTRIBUTED parameter systems ,DISCRETE systems - Published
- 2022
- Full Text
- View/download PDF
17. IEEE Control Systems Society.
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COMMITTEES - Abstract
Provides a listing of current committee members and society officers. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
- View/download PDF
18. IEEE Control Systems Society.
- Subjects
COMMITTEES - Abstract
Provides a listing of current committee members and society officers. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
19. IEEE Control Systems Society.
- Subjects
EDITORIAL boards - Abstract
Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
20. IEEE Control Systems Society.
- Subjects
EDITORIAL boards - Abstract
Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
21. IEEE Control Systems Society.
- Subjects
EDITORIAL boards - Abstract
Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
22. IEEE Control Systems Society.
- Subjects
EDITORIAL boards - Abstract
Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
23. TechRxiv: Share Your Preprint Research with the World!
- Subjects
- *
MANUSCRIPTS - Abstract
Prospective authors are requested to submit new, unpublished manuscripts for inclusion in the upcoming event described in this call for papers. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
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24. Distributed Antiwindup Consensus Control of Heterogeneous Multiagent Systems Over Markovian Randomly Switching Topologies.
- Author
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Wang, Jingyao, Wen, Guanghui, and Duan, Zhisheng
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MULTIAGENT systems ,DISTRIBUTED algorithms ,TOPOLOGY ,PROBLEM solving - Abstract
The consensus control of multiagent systems (MASs) over randomly switching communication topologies has drawn increasing attention from researchers, since the mean square consensus or the most surely consensus is significant and practical. This manuscript focuses on the output consensus problem for heterogeneous MASs with input saturation constraints over the Markovian randomly switching topologies. The main challenge of solving the concerned problem lies in the interplay among the heterogeneous dynamics, input saturation constraints and the Markovian randomly switching topologies. To overcome such a challenge, a class of distributed adaptive observers is first designed for all agents to deal with the uncertainty caused by the randomly switching topologies. Then, a class of local state observers is presented for estimating each agent’s state information. Based on the above steps, a class of antiwindup controllers is constructed and the control gain matrices are selected using only the dynamics information of each node. Finally, the effectiveness of the consensus protocol is demonstrated. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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25. Table of Contents.
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NONHOLONOMIC dynamical systems ,STABILITY of nonlinear systems ,ROBUST stability analysis ,MARKOVIAN jump linear systems ,LINEAR dynamical systems ,LINEAR control systems - Published
- 2022
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26. Optimal Transport for a Class of Linear Quadratic Differential Games.
- Author
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Adu, Daniel Owusu, Basar, Tamer, and Gharesifard, Bahman
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DIFFERENTIAL games ,QUADRATIC differentials ,PROBABILITY measures ,CONVEX functions ,DUALITY theory (Mathematics) ,UNCERTAIN systems - Abstract
We consider a setting where two noncooperative players optimally influence the evolution of an initial spatial probability in a game-theoretic hierarchical fashion (Stackelberg differential game), so that at a specific final time the distribution of the state matches a given final target measure. We provide a sufficient condition for the existence and uniqueness of an optimal transport map and prove that it can be characterized as the gradient of some convex function. An important by-product of our formulation is that it provides a means to study a class of Stackelberg differential games where the initial and final states of the underlying system are uncertain, but drawn randomly from some probability measures. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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27. Linear Reduced-Order Model Predictive Control.
- Author
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Lorenzetti, Joseph, McClellan, Andrew, Farhat, Charbel, and Pavone, Marco
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REDUCED-order models ,PREDICTION models ,PARTIAL differential equations ,DISCRETIZATION methods ,CONSTRAINT satisfaction ,COMPUTATIONAL fluid dynamics - Abstract
Model predictive controllers use dynamics models to solve constrained optimal control problems. However, computational requirements for real-time control have limited their use to systems with low-dimensional models. Nevertheless, high-dimensional models arise in many settings, for example, discretization methods for generating finite-dimensional approximations to partial differential equations can result in models with thousands to millions of dimensions. In such cases, reduced-order models (ROMs) can significantly reduce computational requirements, but model approximation error must be considered to guarantee controller performance. In this article, a reduced-order model predictive control (ROMPC) scheme is proposed to solve robust, output feedback, constrained optimal control problems for high-dimensional linear systems. Computational efficiency is obtained by using projection-based ROMs, and guarantees on robust constraint satisfaction and stability are provided. The performance of the approach is demonstrated in simulation for several examples, including an aircraft control problem leveraging an inviscid computational fluid dynamics model with dimension 998 930. [ABSTRACT FROM AUTHOR]
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- 2022
- Full Text
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28. A Lyapunov Approach to Robust Cooperative Output Regulation of Multiagent Systems Under Infinite Communication Delays.
- Author
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Zhou, Qianghui, Xu, Xiang, Liu, Lu, and Feng, Gang
- Subjects
MULTIAGENT systems ,LINEAR systems ,FREQUENCY-domain analysis ,DISTRIBUTED algorithms ,PRIOR learning ,DISTRIBUTED computing - Abstract
This article investigates the robust cooperative output regulation problem of heterogeneous uncertain linear multiagent systems with switching topologies and infinite distributed communication delays. A novel distributed observer is proposed for each agent to estimate the state of the so-called exosystem by taking consideration of both switching topologies and infinite distributed communication delays. A distributed output feedback controller is then developed based on the internal model principle and the estimated state without using the prior knowledge of communication delays. It is shown via the newly developed Lyapunov-like method that the robust cooperative output regulation problem can be solved under some mild assumptions. Finally, a numerical example is given to demonstrate the effectiveness of the proposed controller. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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29. Consensusability Margin Optimization for Second-Order Multiagent Systems With Communication Uncertainties.
- Author
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Rong, Lina
- Subjects
TELECOMMUNICATION systems ,MULTIAGENT systems ,DISCRETE-time systems ,CLOSED loop systems ,MATRIX functions - Abstract
In this article, the $\mathcal {H}_{\infty }$ optimization approach is used to study the consensusability margin optimization problems for distributed second-order sampled-data multiagent systems with communication uncertainties. The considered uncertainties are frequency-dependent and bounded in $\mathcal {H}_{\infty }$ norms. Specifically, for both the state-based protocols with relative damping and absolute damping, this article attempts to answer two questions: 1) how to characterize the control parameters for achieving robust consensus; and 2) what is the maximal consensusability margin and how to find, if one exists, the parameter to achieve this optimal performance. It is shown that the consensusability margin optimization problems are constraint optimization problems, which are to be specified by specific problem parameters and can be discussed by designing the network complementary sensitivity function matrices of the closed-loop multiagent systems. Moreover, it is shown that the infimums of the $\mathcal {H}_{\infty }$ norms of the network complementary sensitivity function matrices under both protocols are independent of network topologies. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
30. Exact Detectability of Discrete-Time and Continuous-Time Linear Stochastic Systems: A Unified Approach.
- Author
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Dragan, Vasile, Costa, Eduardo F., Popa, Ioan-Lucian, and Aberkane, Samir
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STOCHASTIC systems ,LINEAR systems ,WHITE noise ,MARKOV processes ,TIME-varying systems ,SYMMETRIC matrices - Abstract
This article is devoted to the problem of detectability of a large class of linear stochastic systems with time varying coefficients simultaneously affected by state multiplicative white noise perturbations and Markovian switching. The main contribution of this article is to propose a Popov–Belevich–Hautus-type test, which is equivalent to the detectability of the considered stochastic systems in the sense that all unstable modes produce some nonzero output. The proposed setting unifies in some sense the discrete-time and continuous-time ones, dissimilarly to the vast majority of existing works that study discrete and continuous time separately. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
31. Q-Learning With Uniformly Bounded Variance.
- Author
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Devraj, Adithya M. and Meyn, Sean P.
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FUNCTIONS of bounded variation ,STOCHASTIC control theory - Abstract
Sample complexity bounds are a common performance metric in the reinforcement learning literature. In the discounted cost, infinite horizon setting, all of the known bounds can be arbitrarily large, as the discount factor approaches unity. These results seem to imply that a very large number of samples is required to achieve an epsilon-optimal policy. The objective of the present work is to introduce a new class of algorithms that have sample complexity uniformly bounded over all discount factors. One may argue that this is impossible, due to a recent min–max lower bound. The explanation is that these prior bounds concern value function approximation and not policy approximation. We show that the asymptotic covariance of the tabular Q-learning algorithm with an optimized step-size sequence is a quadratic function of a factor that goes to infinity, as discount factor approaches 1; an essentially known result. The new relative Q-learning algorithm proposed here is shown to have asymptotic covariance that is uniformly bounded over all discount factors. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
32. A Novel Fixed-Time Protocol for First-Order Consensus Tracking With Disturbance Rejection.
- Author
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Xu, Yong, Yao, Zhaozhan, Lu, Renquan, and Ghosh, Bijoy K.
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MULTIAGENT systems ,SPANNING trees ,SLIDING mode control ,DESIGN techniques - Abstract
This technical note studies fixed-time consensus tracking with disturbance rejection for first-order multiagent systems. The communication topology among the leader and followers contains a directed spanning tree. The control input to the leader is time-varying and unknown to the followers, except that its upper bound is known a priori. A novel fixed-time protocol is devised based on discontinuous and nonlinear control. A fixed-time stability analysis for consensus tracking with disturbance rejection is completed as a one-step control process using nonsmooth analysis. An upper bound estimate for the settling time, independent of the initial conditions, is aesthetically pleasing, in comparison to previous results derived based on two-step control design technique using sliding modes. Finally, a numeric example confirms the theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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33. An Asynchronous Gradient Descent Based Method for Distributed Resource Allocation With Bounded Variables.
- Author
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Wang, Yifan, Zhao, Qianchuan, and Wang, Xuetao
- Subjects
RESOURCE allocation ,TELECOMMUNICATION systems ,DISTRIBUTED algorithms ,TIME-varying networks ,DEGREES of freedom ,COMMUNICATION barriers - Abstract
This article considers the distributed resource allocation problem over a network of n agents with individual optimization functions and coupled resource constraints. The optimization variables are bounded for each agent. We propose an asynchronous distributed gradient descent based method, which is able to tackle time-varying communication networks and communication problems. The main ideas are twofold. First, the degree of freedom of the network is reduced to deal with the global constraint. Second, we utilize delay compensation to counteract the delay of asynchronous communication. We prove that the convergence rate is $O(\frac{1}{k})$ and analyze both the communication complexity and the time complexity. This method is applied into the parallel pump control problem in HVAC system and shows good numerical results. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
34. On Self-Learning Mechanism for the Output Regulation of Second-Order Affine Nonlinear Systems.
- Author
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Wu, Haiwen, Xu, Dabo, and Jayawardhana, Bayu
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NONLINEAR systems ,EULER-Lagrange system - Abstract
This article studies global robust output regulation of second-order nonlinear systems with input disturbances that encompass the fully-actuated Euler–Lagrange systems. We assume the availability of relative output (w.r.t. a family of reference signals) and output derivative measurements. Based on a specific separation principle and self-learning mechanism, we develop an internal model-based controller that does not require a priori knowledge of reference and disturbance signals and it only assumes that the kernels of these signals are a family of exosystems with unknown parameters (e.g., amplitudes, frequencies, or time periods). The proposed control framework has a self-learning mechanism that extricates itself from requiring absolute position measurement nor precise knowledge of the feedforward kernel signals. By requiring the high-level task/trajectory planner to use the same class of kernels in constraining the trajectories, the proposed low-level controller is able to learn the desired trajectories, to suppress the disturbance signals, and to adapt itself to the uncertain plant parameters. The framework enables a plug-and-play control mechanism in both levels of control. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
35. A Decentralized Primal-Dual Method for Constrained Minimization of a Strongly Convex Function.
- Author
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Hamedani, Erfan Yazdandoost and Aybat, Necdet Serhat
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CONVEX functions ,NONLINEAR functions ,TELECOMMUNICATION systems ,TIME-varying networks ,LOCAL mass media ,DISTRIBUTED algorithms - Abstract
We propose decentralized primal-dual methods for cooperative multiagent consensus optimization problems over both static and time-varying communication networks, where only local communications are allowed. The objective is to minimize the sum of agent-specific convex functions over conic constraint sets defined by agent-specific nonlinear functions; hence, the optimal consensus decision should lie in the intersection of these private sets. Under the strong convexity assumption, we provide convergence rates for suboptimality, infeasibility, and consensus violation in terms of the number of communications required; examine the effect of underlying network topology on the convergence rates. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
36. Event-Based Finite-Time Control for High-Order Interconnected Nonlinear Systems With Asymmetric Output Constraints.
- Author
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Hua, Chang-Chun, Li, Qi-Dong, and Li, Kuo
- Subjects
NONLINEAR systems ,STABILITY theory ,CLOSED loop systems ,LYAPUNOV functions ,PROBLEM solving - Abstract
This article aims to solve the problem of decentralized event-based finite-time control for a class of high-order interconnected nonlinear systems with an asymmetric output constraint. In order to achieve finite-time stability and reduce the update frequency of the controller, a novel controller and its event-trigger mechanism is proposed by adding a power integral technique and utilizing sign function. To fulfill the requirement of asymmetric output constraints, an asymmetric barrier Lyapunov function (BLF) is constructed, which is different from tan-type and log-type BLFs. Based on the contradictory idea and finite-time stability theory, it is proved that there is no Zeno phenomenon under this event-trigger mechanism and all state variables of the closed-loop system attenuate to the origin in the finite-time while the output signals never violate the constraint. Furthermore, the result in this article is expanded to fixed-time control. Finally, a simulation example is given to demonstrate the effectiveness of the presented strategy. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
37. A Sharp Estimate on the Transient Time of Distributed Stochastic Gradient Descent.
- Author
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Pu, Shi, Olshevsky, Alex, and Paschalidis, Ioannis Ch.
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SMOOTHNESS of functions ,COST functions ,STOCHASTIC programming ,INFORMATION sharing ,LINEAR programming - Abstract
This article is concerned with minimizing the average of $n$ cost functions over a network, in which agents may communicate and exchange information with each other. We consider the setting where only noisy gradient information is available. To solve the problem, we study the distributed stochastic gradient descent (DSGD) method and perform a nonasymptotic convergence analysis. For strongly convex and smooth objective functions, in expectation, DSGD asymptotically achieves the optimal network-independent convergence rate compared to centralized stochastic gradient descent. Our main contribution is to characterize the transient time needed for DSGD to approach the asymptotic convergence rate. Moreover, we construct a “hard” optimization problem that proves the sharpness of the obtained result. Numerical experiments demonstrate the tightness of the theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
38. On Observability of Hybrid Systems.
- Author
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Lin, Feng, Wang, Le Yi, Chen, Wen, and Polis, Michael P.
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HYBRID systems ,BATTERY management systems - Abstract
Observability of a hybrid system is defined as the ability to determine the continuous state of the system. Whether a hybrid system is observable or not depends on which events can be disabled, which events can be forced, and the connectivity of the discrete states, as well as its continuous dynamics. We model a hybrid system using a hybrid machine that takes into consideration both continuous variables and discrete events. We classify hybrid systems into four classes based on their discrete-event parts. For each class, conditions are derived to check observability. If a hybrid system is not observable, then we check if a weaker version of observability, called $B$ -observability, is satisfied. $B$ -observability requires that a hybrid system become observable after some finite occurrences of events. Conditions are derived to check $B$ -observability. These conditions involve both the discrete-event and continuous-variable parts of hybrid systems. If the continuous-variable part of a system has a constant- $A$ matrix, then the conditions for the continuous-variable part can be simplified. We illustrate the results by an example of a battery management system of an electric vehicle. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
39. A Semiglobal Approach for Stabilizing Nonlinear Systems With State Delays by Memoryless Linear Feedback.
- Author
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Wang, Yuanjiu and Lin, Wei
- Subjects
NONLINEAR systems ,LINEAR systems ,PSYCHOLOGICAL feedback ,STATE feedback (Feedback control systems) ,NONLINEAR dynamical systems ,LYAPUNOV functions - Abstract
This article investigates the problem of how to control nonlinear systems with delays in the state by memoryless linear feedback. The notions of semiglobal asymptotic stabilization and sublevel sets are introduced in the context of time-delay systems. With the aid of Razumikhin theorem, we develop a semiglobal design method for the construction of Lyapunov functions, associated sublevel sets, and delay-free linear state feedback laws, step-by-step, achieving semiglobal asymptotic stabilization for time-delay nonlinear systems in a lower triangular form. In contrast to the global stabilization of nonlinear systems with delays in the state, which is usually achieved by dynamic state feedback (Lin and Zhang, 2020), the significance of this work is to point out that a tradeoff of the control objectives, e.g., semiglobal versus global stabilization, makes it possible to control a class of time-delay nonlinear systems by static linear feedback. Extensions to nonlinear systems with globally asymptotically locally expoentially stable (GALES)-like inverse dynamics are also included in this article. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
40. Boundary Stability Criterion for a Nonlinear Axially Moving Beam.
- Author
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Cheng, Yi, Wu, Yuhu, and Guo, Bao-Zhu
- Subjects
STABILITY criterion ,EXPONENTIAL stability ,PARTIAL differential equations ,NONLINEAR differential equations ,FINITE element method - Abstract
This article deals with, in the framework of absolute stability, boundary stabilization for a nonlinear axially moving beam under boundary velocity feedback controls. The nonlinear boundary control that satisfies a slope-sector condition covering many types of nonlinear control schemes is a negative feedback of the transverse velocity at the right eyelet of the moving beam. Under the nonlinear control scheme, the well-posedness of the nonlinear partial differential equation, which depends continuously on the initial value is investigated by means of the Faedo–Galerkin approximation and priori estimates. By exploiting the integral-type multiplier method, the exponential stability of the closed-loop system is established, where a novel energy like function is constructed. The numerical simulation examples using the finite element method are presented to illustrate the effectiveness of the established criterion of the controller. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
41. Homogeneity, Forward Completeness, and Global Stabilization of a Family of Time-Delay Nonlinear Systems by Memoryless Non-Lipschitz Continuous Feedback.
- Author
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Zhao, Congran and Lin, Wei
- Subjects
MEMORYLESS systems ,STATE feedback (Feedback control systems) ,CLOSED loop systems ,HOMOGENEITY ,ADAPTIVE fuzzy control ,NONLINEAR systems - Abstract
For a family of genuinely nonlinear systems with delays in the input and state, global strong stabilization (GSS) in the sense of Kurzweil is shown to be possible by memoryless state and/or output feedback under two conditions: 1) The input delay is within an appropriate range although the state delays can be sufficiently large; 2) the time-delay bounding system is homogeneous of degree zero and has a lower triangular structure. The proof is based on the Lyapunov–Krasovskii functional theorem combined with the homogeneous domination philosophy. Using the emulation approach, we design memoryless homogeneous state and output feedback controllers, respectively, achieving GSS of the time-delay closed-loop systems with severe nonlinearity. Extensions to a wider class of time-delay nonlinear systems in the Hessenberg form are also given. Examples and counter-examples presented in this article illustrate not only the necessity of the homogeneous growth conditions but also the significance of the memoryless non-Lipschitz continuous feedback control strategies. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
42. Controller Reduction for Nonlinear Systems by Generalized Differential Balancing.
- Author
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Kawano, Yu
- Subjects
NONLINEAR systems ,LINEAR matrix inequalities ,LINEAR systems ,CLOSED loop systems - Abstract
In this article, we aim at developing computationally tractable methods for nonlinear model/controller reduction. Recently, model reduction by generalized differential (GD) balancing has been proposed for nonlinear systems with constant input-vector fields and linear output functions. First, we study incremental properties in the GD balancing framework. Next, based on these analyses, we provide GD linear quadratic Gaussian (LQG) balancing and GD $H_\infty$ -balancing as controller reduction methods for nonlinear systems by focusing on linear feedback and observer gains. Especially for GD $H_\infty$ -balancing, we clarify when the closed-loop system consisting of the full-order system and a reduced-order controller is exponentially stable. All provided methods for controller reduction can be relaxed to linear matrix inequalities (LMIs). [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
43. Group Consensus of Linear Multiagent Systems Under Nonnegative Directed Graphs.
- Author
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Liu, Zhongchang and Wong, Wing Shing
- Subjects
MULTIAGENT systems ,DIRECTED graphs ,LINEAR systems ,SPANNING trees ,TECHNOLOGICAL innovations ,TOPOLOGY - Abstract
Group consensus implies reaching multiple groups where agents belonging to the same cluster reach state consensus. This article focuses on linear multiagent systems under nonnegative directed graphs. A new necessary and sufficient condition for ensuring group consensus is derived, which requires the spanning forest of the underlying directed graph and that of its quotient graph induced with respect to a clustering partition to contain equal minimum number of directed trees. This condition is further shown to be equivalent to containing cluster spanning trees, a commonly used topology for the underlying graph in the literature. Under a designed controller gain, lower bound of the overall coupling strength for achieving group consensus is specified. Moreover, the pattern of the multiple consensus states formed by all clusters is characterized when the overall coupling strength is large enough. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
44. Integral-Input-to-State Stability of Switched Nonlinear Systems Under Slow Switching.
- Author
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Liu, Shenyu, Russo, Antonio, Liberzon, Daniel, and Cavallo, Alberto
- Subjects
STABILITY of nonlinear systems - Abstract
In this article we study integral-input-to-state stability (iISS) of nonlinear switched systems with jumps. We demonstrate by examples that iISS is not always preserved under slow enough dwell time switching, and then we present sufficient conditions for iISS to be preserved under slow switching. These conditions involve, besides a sufficiently large dwell time, some additional properties of comparison functions characterizing iISS of the individual modes. When the sufficient conditions that guarantee iISS are only partially satisfied, we are then able to conclude weaker variants of iISS, also introduced in this work. As an illustration, we show that switched systems with bilinear zero-input-stable modes are always iISS under sufficiently large dwell time. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
45. When is a Matrix of Dimension Three Similar to a Metzler Matrix? Application to Interval Observer Design.
- Author
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Mazenc, Frederic and Bernard, Olivier
- Subjects
TRANSFER matrix ,TRANSMISSION line matrix methods ,LINEAR matrix inequalities ,INTERVAL analysis ,LIMIT cycles - Abstract
A simple, necessary, and sufficient condition ensuring that a real matrix of dimension three is similar to a Metzler matrix is exhibited. When this condition is satisfied, a construction of the transfer matrix is given. This construction is used to design an interval observer for a family of continuous-time systems. An example is provided with interval observer design for the so-called love dynamics in the case of limit cycles [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
46. The Covariance Extension Equation: A Riccati-Type Approach to Analytic Interpolation.
- Author
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Cui, Yufang and Lindquist, Anders
- Subjects
INTERPOLATION ,ROBUST control ,EQUATIONS ,KALMAN filtering ,COVARIANCE matrices - Abstract
Analytic interpolation problems with rationality and derivative constraints are ubiquitous in systems and control. This article provides a new method for such problems, both in the scalar and matrix case, based on a nonstandard Riccati-type equation. The rank of the solution matrix is the same as the degree of the interpolant, thus providing a natural approach to model reduction. A homotopy continuation method is presented and applied to some problems in modeling and robust control. We also address a question on the positive degree of a covariance sequence originally posed by Kalman. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
47. Limiting Behavior of Hybrid Time-Varying Systems.
- Author
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Lee, Ti-Chung, Tan, Ying, and Mareels, Iven
- Subjects
TIME-varying systems ,HYBRID systems ,GLOBAL asymptotic stability ,DYNAMICAL systems ,LYAPUNOV functions ,NONLINEAR systems - Abstract
Checking uniform attractivity of a time-varying dynamic system without a strict Lyapunov function is challenging as it requires the characterization of the limiting behavior of a set of trajectories. In the context of hybrid nonlinear time-varying systems, characterizing such limiting or convergent behaviors is even harder due to the complexity stemming from both continuous-time variations as well as discrete-time jumps. In this article, an extension of the standard hybrid time domain is introduced to define limiting behaviors, using set convergence, when time approaches either positive infinity or negative infinity. In particular, it is shown how to characterize limiting behaviors under the condition that an output signal approaches zero. Such limiting behaviors and their associated limiting systems can be used to verify uniform global attractivity. Particularly, a generalization of the classic Krasovskii–LaSalle theorem is obtained for hybrid time-varying systems. Two examples are used to demonstrate the effectiveness of the results. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
48. Table of Contents.
- Abstract
Presents the table of contents for this issue of the publication. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
49. Sensor Fault-Tolerant State Estimation by Networks of Distributed Observers.
- Author
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Yang, Guitao, Rezaee, Hamed, Serrani, Andrea, and Parisini, Thomas
- Subjects
SENSOR networks ,DETECTORS ,SYMMETRIC matrices - Abstract
We propose a state estimation methodology using a network of distributed observers. We consider a scenario in which the local measurement at each node may not guarantee the system's observability. In contrast, the ensemble of all the measurements does ensure that the observability property holds. As a result, we design a network of observers such that the estimated state vector computed by each observer converges to the system's state vector by using the local measurement and the communicated estimates of a subset of observers in its neighborhood. The proposed estimation scheme exploits sensor redundancy to provide robustness against faults in the sensors. Under suitable conditions on the redundant sensors, we show that it is possible to mitigate the effects of a class of sensor faults on the state estimation. Simulation trials demonstrate the effectiveness of the proposed distributed estimation scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
50. Optimal Transmission Power and Controller Design for Networked Control Systems Under State-Dependent Markovian Channels.
- Author
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Hu, Bin and Tamba, Tua A.
- Subjects
POWER transmission ,BUSINESS communication ,SEMIDEFINITE programming ,INDUSTRIAL controls manufacturing ,WIRELESS communications ,MOBILE communication systems ,RADIO transmitter fading - Abstract
This article considers a codesign problem for industrial networked control systems to ensure both stability and efficiency properties of such systems. This problem is particularly challenging due to the fact that wireless communications in industrial environments are not only subject to shadow fading, but also stochastically correlated with their surrounding environments. This article first introduces a novel state-dependent Markov channel (SD-MC) model that explicitly captures the state-dependent features of industrial wireless communication systems by defining the proposed model’s transition probabilities as a function of both environments’ states and transmission power. Under the SD-MC model, sufficient conditions on Maximum Allowable Transmission Interval are presented to ensure both asymptotic stability in expectation and almost sure asymptotic stability properties of a nonlinear control system with state-dependent fading channels. Based on these stability conditions, the codesign problem is then formulated as a constrained polynomial optimization problem (CPOP), which can be efficiently solved using semidefinite programming methods for the case of a two-state SD-MC model. The solutions to such a CPOP represent optimal control and power strategies that optimize the average expected joint costs in an infinite time horizon while respecting the stability constraints. For a general SD-MC model, this article further shows that suboptimal solutions can be obtained from linear programming formulations of the considered CPOP. Simulation results are given to illustrate the efficacy of the proposed codesign scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
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