List of English Publication

@article{nokey,

title = {Singularly Perturbed Hybrid Systems for Analysis of Networks With Frequently Switching Graphs},

author = {Aneel Tanwani and Hyungbo Shim and Andrew R. Teel},

doi = {10.1109/TAC.2024.3523242},

issn = {0018-9286},

year  = {2025},

date = {2025-07-01},

urldate = {2025-07-01},

journal = {IEEE Transactions on Automatic Control},

volume = {70},

issue = {7},

pages = {4344-4359},

abstract = {For a class of hybrid systems, where jumps occur frequently, we analyze the stability of system trajectories in view of singularly perturbed dynamics. The specific model we consider comprises an interconnection of two hybrid subsystems, a timer which triggers the jumps, and some discrete variables to determine the index of the jump maps. The flow equations of these variables are singularly perturbed differential equations and, in particular, a smaller value of the singular perturbation parameter leads to an increase in the frequency of the jump instants. For the limiting value of this parameter, we consider a decomposition that comprises a quasi-steady-state system modeled by a differential equation without any jumps and a boundary-layer system described by purely discrete dynamics. Under appropriate assumptions on the quasi-steady-state system and the boundary-layer system, we derive results showing practical stability of a compact attractor when the jumps occur sufficiently often. As an application of our results, we discuss the control design problem in a network of second-order continuous-time coupled oscillators, where each agent communicates the information about its position to some of its neighbors at discrete times. Using the results developed in this article, we show that if the union of the communication graphs being used for information exchange between agents is connected, then the oscillators achieve practical consensus.},

keywords = {Hybrid system, Multi-agent systems, Singular perturbation},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A Distributed Observer Accommodating a Broad Range of Intermittent Communication Scenarios},

author = {Sunghyun Koo and Jin Gyu Lee and Hyungbo Shim},

doi = {https://doi.org/10.1109/LCSYS.2025.3583672},

issn = {2475-1456},

year  = {2025},

date = {2025-06-27},

urldate = {2025-06-27},

journal = {IEEE Control Systems Letters},

volume = {9},

pages = {1682-1687},

abstract = {This paper proposes a distributed observer that utilizes intermittent communication and accommodates a broad range of scenarios, including asynchronous operation, unidirectional communication, packet loss, and communication delays. An analysis over jointly connected switching topology supports this and provides a condition for exponential convergence of the estimation error. This condition can be used to determine a communication rate. The analysis is valid when the unobservable subspace of each agent admits an invariant orthogonal complement. This is a property that is always achievable via a coordinate transformation when the system matrix is diagonalizable over the complex field},

keywords = {distributed observer, Distributed state estimation, Multi-agent systems},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {How Does a Swarm Exhibit Emergent Behavior Through Synchronization?},

author = {Hyungbo Shim},

url = {https://icros.org/publication/sub03_04.asp?sub_param=4},

doi = {https://doi.org/10.5302/J.ICROS.2024.24.0039},

issn = {1976-5622},

year  = {2024},

date = {2024-04-01},

urldate = {2024-04-01},

journal = {Journal of Institute of Control, Robotics and Systems},

volume = {30},

issue = {4},

pages = {352},

abstract = {A swarm of individuals often exhibits behaviors that are not possible for each individual. This phenomenon is called emergence, and this paper mathematically demonstrates that new dynamics can arise in swarm behavior that cannot be explained by the dynamics of individuals. In particular, we argue that emergence occurs when heterogeneity is coupled with synchronization.

These two concepts may seem conflicting, as heterogeneity is the tendency to differ whereas synchronization is the tendency toward sameness. However, we show that emergent behavior arises from the interplay between the two.},

keywords = {Blended dynamics, Multi-agent systems, Synchronization},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Synchronization with prescribed transient behavior: Heterogeneous multi-agent systems under funnel coupling},

author = {Jin Gyu Lee and Stephan Trenn and Hyungbo Shim},

url = {https://www.sciencedirect.com/science/article/pii/S0005109822001224},

doi = {https://doi.org/10.1016/j.automatica.2022.110276},

issn = {0005-1098},

year  = {2022},

date = {2022-07-01},

urldate = {2022-07-01},

journal = {Automatica},

volume = {141},

pages = {110276},

abstract = {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.},

keywords = {Funnel control, Heterogeneous multi-agents, Multi-agent systems, Synchronization},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Simultaneous distributed localization, mapping and formation control of mobile robots based on local relative measurements},

author = {Miao Guo and Bayu Jayawardhana and Jin Gyu Lee and Hyungbo Shim},

url = {https://www.sciencedirect.com/science/article/pii/S2405896320331426},

doi = {https://doi.org/10.1016/j.ifacol.2020.12.2454.},

issn = {2405-8963},

year  = {2020},

date = {2020-07-11},

journal = {IFAC-PapersOnLine},

volume = {53},

issue = {2},

pages = {9614-9620},

abstract = {This paper investigates the problem of localizing a team of robots in an indoor environment while simultaneously keeping a robust formation and performing group motion. A distributed observer is proposed to estimate the positions of mobile robots as well as the landmarks under a common global frame. Every robot uses its available local relative measurements, as well as the estimated relative measurements to its neighbors in order to keep a robust formation. Simultaneously, each robot estimates the positions of all the landmarks based on the available on-board relative measurements but also based on the estimated positions from its neighbors. We provide the L2-stability analysis of the closed-loop system where the group is also allowed to maneuver in the unknown environment. Simulation results are also given to show the efficacy of the method.},

keywords = {Distributed algorithm, Formation control, Multi-agent systems},

pubstate = {published},

tppubtype = {article}

}

@article{SeoShimBack09,

title = {Consensus of High-order Linear Systems using Dynamic Output Feedback Compensator: Low Gain Approach},

author = {Jin Heon Seo and Hyungbo Shim and Juhoon Back},

doi = {10.1016/j.automatica.2009.07.022},

issn = {0005-1098},

year  = {2009},

date = {2009-11-01},

journal = {Automatica},

volume = {45},

number = {11},

pages = {2659-2664},

abstract = {In this paper, we study the consensus (and synchronization) problem for multi-agent linear dynamic systems. All the agents have identical MIMO linear dynamics which can be of any order, and only the output information of each agents is delivered throughout the communication network. It is shown that consensus is reached if there exists a stable compensator which simultaneously stabilizes  systems in a special form, where  is the number of agents. We show that there exists such a compensator under a very general condition. Finally, the consensus value is characterized as a function of initial conditions with stable compensators in place.},

keywords = {Multi-agent systems},

pubstate = {published},

tppubtype = {article}

}