2023 |
Jin Gyu Lee / Thomas Berger / Stephan Trenn / Hyungbo Shim Edge-wise funnel output synchronization of heterogeneous agents with relative degree one Journal Article In: Automatica, vol. 156, pp. 111204, 2023, ISSN: 0005-1098. Abstract | Links | BibTeX | Tags: Blended dynamics, Funnel control, Heterogeneous multi-agents, output synchronization @article{nokey, When a group of heterogeneous node dynamics are diffusively coupled with a high coupling gain, the group exhibits a collective emergent behavior which is governed by a simple algebraic average of the node dynamics called the blended dynamics. This finding has been utilized for designing heterogeneous multi-agent systems by building the desired blended dynamics first and then splitting it into the node dynamics. However, to compute the magnitude of the coupling gain, each agent needs to know global information such as the number of participating nodes, the graph structure, and so on, which prevents a fully decentralized design of the node dynamics in conjunction with the coupling laws. To resolve this issue, the idea of funnel control, which is a method for adaptive gain selection, can be exploited for a node-wise coupling, but the price to pay is that the collective emergent behavior is no longer governed by a simple average of the node dynamics. Our analysis reveals that this drawback can be avoided by an edge-wise design premise, which is the idea that we present in this paper. After all, we gain benefits such as a fully decentralized design without global information, collective emergent behavior being governed by the blended dynamics, and the plug-and-play operation based on edge-wise handshaking between two nodes |
2022 |
Jin Gyu Lee / Stephan Trenn / Hyungbo Shim Synchronization with prescribed transient behavior: Heterogeneous multi-agent systems under funnel coupling Journal Article In: Automatica, vol. 141, pp. 110276, 2022, ISSN: 0005-1098. Abstract | Links | BibTeX | Tags: Funnel control, Heterogeneous multi-agents, Multi-agent systems, Synchronization @article{nokey, In this paper, we introduce a nonlinear time-varying coupling law, which can be designed in a fully decentralized manner and achieves approximate synchronization with arbitrary precision, under only mild assumptions on the individual vector fields and the underlying (undirected) graph structure. The proposed coupling law is motivated by the so-called funnel control method studied in adaptive control under the observation that arbitrary precision synchronization can be achieved for heterogeneous multi-agent systems by a high-gain coupling; consequently we call our novel synchronization method ‘(node-wise) funnel coupling.’ By adjusting the conventional proof technique in the funnel control study, we are even able to obtain asymptotic synchronization with the same funnel coupling law. Moreover, the emergent collective behavior that arises for a heterogeneous multi-agent system when enforcing arbitrary precision synchronization by the proposed funnel coupling law, is analyzed in this paper. In particular, we introduce a single scalar dynamics called ‘emergent dynamics’ which describes the emergent synchronized behavior of the multi-agent system under funnel coupling. Characterization of the emergent dynamics is important because, for instance, one can design the emergent dynamics first such that the solution trajectory behaves as desired, and then, provide a design guideline to each agent so that the constructed vector fields yield the desired emergent dynamics. We illustrate this idea via the example of a distributed median solver based on funnel coupling. |
2020 |
Jin Gyu Lee / Thomas Berger / Stephan Trenn / Hyungbo Shim Utility of Edge-wise Funnel Coupling for Asymptotically Solving Distributed Consensus Optimization Proceedings Article In: Proc. of 2020 European Control Conference (ECC), pp. 911-916, IEEE, St. Petersburg, Russia, 2020, ISBN: 978-3-90714-402-2. Abstract | Links | BibTeX | Tags: Distributed optimization, Funnel control, Multi-agent systems @inproceedings{nokey, A new approach to distributed consensus optimization is studied in this paper. The cost function to be minimized is a sum of local cost functions which are not necessarily convex as long as their sum is convex. This benefit is obtained from a recent observation that, with a large gain in the diffusive coupling, heterogeneous multi-agent systems behave like a single dynamical system whose vector field is simply the average of all agents' vector fields. However, design of the large coupling gain requires global information such as network structure and individual agent dynamics. In this paper, we employ a nonlinear time-varying coupling of diffusive type, which we call `edge-wise funnel coupling.' This idea is borrowed from adaptive control, which enables decentralized design of distributed optimizers without knowledge of global information. Remarkably, without a common internal model, each agent achieves asymptotic consensus to the optimal solution of the global cost. We illustrate this result by a network that asymptotically finds the least-squares solution of a linear equation in a distributed manner. |
2017 |
Jin Gyu Lee / Hyungbo Shim Synchronized Behavior of Heterogeneous Multi-agent Systems Under Funnel Coupling Proceedings Article In: Proc. of SWARM 2017: The 2nd International Symposium on Swarm Behavior and Bio-Inspired Robotics, pp. 266-269, Kyoto, Japan, 2017. Abstract | Links | BibTeX | Tags: Funnel control, Practical synchronization @inproceedings{LeeShim17b, First,generalizationofthefunnelcontrolbasedcouplinglawisprovidedtoachieveapracticalsynchronization. In addition to this, we detail the discussion on the synchronized behavior of heterogeneous agents under funnel coupling. In particular, emergent dynamics has been conjectured, which can predict the synchronized behavior by its solution trajectory. Discussion and comparison associated with the similar concept named blended dynamics in strong coupling technique have been given, and also the effectiveness of our conjecture is illustrated by simulations. |
List of English Publication
2023 |
Edge-wise funnel output synchronization of heterogeneous agents with relative degree one Journal Article In: Automatica, vol. 156, pp. 111204, 2023, ISSN: 0005-1098. |
2022 |
Synchronization with prescribed transient behavior: Heterogeneous multi-agent systems under funnel coupling Journal Article In: Automatica, vol. 141, pp. 110276, 2022, ISSN: 0005-1098. |
2020 |
Utility of Edge-wise Funnel Coupling for Asymptotically Solving Distributed Consensus Optimization Proceedings Article In: Proc. of 2020 European Control Conference (ECC), pp. 911-916, IEEE, St. Petersburg, Russia, 2020, ISBN: 978-3-90714-402-2. |
2017 |
Synchronized Behavior of Heterogeneous Multi-agent Systems Under Funnel Coupling Proceedings Article In: Proc. of SWARM 2017: The 2nd International Symposium on Swarm Behavior and Bio-Inspired Robotics, pp. 266-269, Kyoto, Japan, 2017. |