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作者：Han, Dongyu; Liu, Kun; Lin, Yeming; Xia, Yuanqing
作者单位：Beijing Institute of Technology
摘要：This article considers a distributed stochastic nonconvex optimization problem, where the nodes in a network cooperatively minimize a sum of $L$-smooth local cost functions with sparse gradients. By adaptively adjusting the stepsizes according to the historical (possibly sparse) gradients, a distributed adaptive gradient algorithm is proposed, in which a gradient tracking estimator is used to handle the heterogeneity between different local cost functions. We establish an upper bound on the op...
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作者：Huang, Kun; Li, Xiao; Pu, Shi
作者单位：The Chinese University of Hong Kong, Shenzhen
摘要：Distributed stochastic optimization has drawn great attention recently due to its effectiveness in solving large-scale machine learning problems. Although numerous algorithms have been proposed and successfully applied to general practical problems, their theoretical guarantees mainly rely on certain boundedness conditions on the stochastic gradients, varying from uniform boundedness to the relaxed growth condition. In addition, how to characterize the data heterogeneity among the agents and i...
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作者：Hustiu, Sofia; Mahulea, Cristian; Kloetzer, Marius; Lesage, Jean-Jacques
作者单位：GH Asachi Technical University; University of Zaragoza; Universite Paris Saclay
摘要：This article proposes a method exploiting the advantages of Petri net (PN) and B & uuml;chi automata models by joining them in a newly defined composed PN representation. Based on the latter model, collision-free trajectories are computed for a team of robots. The path planning algorithm is divided into two steps: computing a solution in a reduced PN model and projecting it to the PN assigned to the environment. The results, given by a set of mixed integer linear programming (MILP) problems, y...
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作者：Sun, Weichao; Yuan, Yeqing; Gao, Huijun
作者单位：Harbin Institute of Technology
摘要：Hierarchical impedance-based tracking control has attracted much interest recently due to its advantages of no external forces/torques feedback and inertia reshaping. Desired trajectories on each hierarchy level can be asymptotically tracked following the order of priorities. However, tasks specified by users are required to have the same dimensions as the DOF of robot and are simultaneously feasible and independent. In this article, all these restrictions are removed and a passivity-based hie...
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作者：Gallegos, Javier A.; Schlotterbeck, Constanza; Nunez, Felipe
作者单位：Pontificia Universidad Catolica de Chile
摘要：Average consensus is a fundamental problem in distributed control that still lacks a general solution when the agents face nonideal conditions and uncertain environments. This note contributes to the topic by addressing average consensus in networks of agents that: 1) interact over a time-varying and nonbalanced environment and 2) face parametric and nonparametric disturbances. It is shown that an adaptive strategy, which combines surplus variables and virtual agents, effectively solves the ex...
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作者：Lin, Li-Yu; Goppert, James; Hwang, Inseok
作者单位：Purdue University System; Purdue University
摘要：In this article, we use the derivative of the exponential map to derive the exact evolution of the logarithm of the tracking error for mixed-invariant systems, a class of systems capable of describing rigid body tracking problems in Lie groups. In addition, we design a log-linear dynamic inversion-based control law to remove the nonlinearities due to spatial curvature and enhance the robustness of the controller. We apply linear matrix inequalities to bound the tracking error given a bounded d...
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作者：Sasahara, Hampei; Sandberg, Henrik
作者单位：Institute of Science Tokyo; Tokyo Institute of Technology; Royal Institute of Technology
摘要：This article addresses the question whether model knowledge can guide a defender to appropriate decisions, or not, when an attacker intrudes into control systems. The model-based defense scheme considered in this study, namely Bayesian defense mechanism, chooses reasonable reactions through observation of the system's behavior using models of the system's stochastic dynamics, the vulnerability to be exploited, and the attacker's objective. On the other hand, rational attackers take deceptive s...
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作者：Afshar, Sepideh; Germ, Fabian; Morris, Kirsten
作者单位：University of Edinburgh; University of Waterloo
摘要：In many physical applications, the system's state varies with spatial variables as well as time. The state of such systems is modeled by partial differential equations and evolves on an infinite-dimensional space. Systems modeled by delay-differential equations are also infinite-dimensional systems. The full state of these systems cannot be measured. Observer design is an important tool for estimating the state from available measurements. For linear systems, both finite- and infinite-dimensio...
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作者：Nuno, Emmanuel; Sarras, Ioannis; Yin, Hao; Jayawardhana, Bayu
作者单位：Universidad de Guadalajara; Universite Paris Saclay; National Office for Aerospace Studies & Research (ONERA); University of Groningen
摘要：We propose a distributed control method to achieve consensus of heterogeneous Euler-Lagrange (EL) systems with bounded time-varying communication delays while simultaneously rejecting periodic external disturbances. Our proposed controller has a simple-to-implement structure of proportional-integral-derivative scheme that employs the internal model approach to reject the disturbance and that it is model-independent (when cancelling the gravity effects). We consider that the network of EL-syste...
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作者：Wang, Yan; Su, Rong
作者单位：Harbin Institute of Technology; Nanyang Technological University
摘要：This article studies the infinite horizon optimal linear quadratic Gaussian control problem (OLCP) of interconnected systems (ISs) with output feedback. The IS is defined over a directed graph, in which the nodes represent subsystems, and the edges represent the communication channels. Because the information transmission time is nonnegligible, we assume that the information traveling across an edge in the graph needs a fixed time. Under the abovementioned setup, the OLCP of ISs with output fe...
