2024 |
Deuksun Hong / Hyungbo Shim A Reinforcement Learning Approach for Safe Control Using Multi-Agent Q-Learning Proceedings Article In: 2024 14th Asian Control Conference, 2024. Abstract | BibTeX | Tags: Consensus, Multi-agent system, Reinforcement learning @inproceedings{nokey, Reinforcement learning techniques typically optimize a controller only for the trained environment. This characteristic leads to trouble when applying the learned models to other settings, particularly in real control scenarios where control needs to be performed under different conditions than those during the learning phase due to modeling errors or aging. This paper introduces a multi-agent version of Q-learning known as QD-learning. We also present how this algorithm operates when applied to the various environment settings, and experimentally demonstrate its effectiveness for designing a safe controller. |
Jin Gyu Lee / Cyrus Mostajeran / Graham Van Goffrier Node-Wise Monotone Barrier Coupling Law for Formation Control Journal Article In: Entropy, vol. 26, iss. 2, pp. 134, 2024, ISSN: 1099-4300. Abstract | Links | BibTeX | Tags: Consensus, Formation control, Nonlinear space, Positivity @article{nokey, We study a node-wise monotone barrier coupling law, motivated by the synaptic coupling of neural central pattern generators. It is illustrated that this coupling imitates the desirable properties of neural central pattern generators. In particular, the coupling law (1) allows us to assign multiple central patterns on the circle and (2) allows for rapid switching between different patterns via simple ‘kicks’. In the end, we achieve full control by partitioning the state space by utilizing a barrier effect and assigning a unique steady-state behavior to each element of the resulting partition. We analyze the global behavior and study the viability of the design. |
2013 |
Dmitry Vengertsev / Hongkeun Kim / Jin Heon Seo / Hyungbo Shim Consensus of output-coupled high-order linear multi-agent systems under deterministic and Markovian switching networks Journal Article In: International Journal of Systems Science, vol. 46, no. 10, pp. 1790-1799, 2013, ISSN: 0020-7721. Abstract | Links | BibTeX | Tags: Consensus, nonlinear @article{VengertsevKimSeoShim13, Consensus problem for high-order multi-agent systems is considered under deterministic and Markovian switching topologies. Only relative output information of agents is assumed to be available through the networks. First, a necessary and sufficient condition for achieving a consensus under a fixed communication network is presented. Based on this result and the stability of switched systems, a high-order multi-agent system with the proposed low-gain controller is shown to reach a consensus under deterministic switching network if the total time when the network is disconnected is, in some senses, smaller than the total time of the network being connected. Furthermore, the conditions sufficient for a high-order multi-agent system to reach an almost sure and mean-square consensus, under Markovian switching networks, are presented. Finally, illustrative examples are given to demonstrate the results. |
2012 |
Jinyoung Lee / Jung-Su Kim / Hyungbo Shim Disc Margins of the Discrete-time LQR and its Application to Consensus Problem Journal Article In: International Journal of Systems Science , vol. 43, no. 10, pp. 1891-1900, 2012. Abstract | Links | BibTeX | Tags: Consensus @article{LeeKimShim12, This article presents a complex gain margin of discrete-time linear quadratic regulator (DLQR) and its application to a consensus problem of multi-agent higher order linear systems. Since the consensus problem can be converted into a robust control problem with perturbation expressed by complex numbers, and since the classical gain and phase margins are not enough to handle the current case, we study the so-called ‘disc margin’ which is somehow a combination of gain and phase margins. We first compute the disc margin of DLQR controller based on a Lyapunov argument, which is simple but yields a relaxed result over those previously reported in the literature. Then, it is shown that the disc margin can be enlarged arbitrarily when the system is asymptotically null controllable with bounded controls and when a low-gain feedback is employed. Based on this fact, the discrete-time consensus problem is solved by a DLQR-based consensus controller. Simulation study shows that the DLQR-based consensus controller has better robustness property against model uncertainties in the input channel. |
2010 |
Jin Heon Seo / Hyungbo Shim / Juhoon Back Reduced-order Consensus Controllers for Output-coupled SISO Linear Systems Journal Article In: International Journal of Control, Automation and Systems, vol. 8, no. 6, pp. 1356-1363, 2010, ISBN: 1598-6446. Abstract | Links | BibTeX | Tags: Consensus @article{SeoShimBack10, In this paper, we continue the study of the consensus problem for multi-agent linear dynamic systems. All the agents have identical linear dynamics which can be of any order, and only the output information of each agents is delivered throughout the communication network. Under these settings, we show that the first-order and the second-order consensus problems can be solved by a first-order and a second-order dynamic filter, respectively. This holds even for high order dynamics, and therefore, the high order system does not have to use a high order consensus controller. |
0000 |
Jiyeon Nam / Jinwook Heo / Jeong Woo Kim / Hyungbo Shim / Jae Sung Bang / Jinsung Kim Initialization-free Algorithm for Discrete-time Dynamic Average Consensus and Its Application to Distributed Optimization Proceedings Article In: International Conference on Control, Automation and Systems (ICCAS 2022), Institute of Control, Robotics and Systems, 0000. BibTeX | Tags: Consensus, Distributed algorithm, Distributed optimization @inproceedings{nokeyk, |
List of English Publication
2024 |
A Reinforcement Learning Approach for Safe Control Using Multi-Agent Q-Learning Proceedings Article In: 2024 14th Asian Control Conference, 2024. |
Node-Wise Monotone Barrier Coupling Law for Formation Control Journal Article In: Entropy, vol. 26, iss. 2, pp. 134, 2024, ISSN: 1099-4300. |
2013 |
Consensus of output-coupled high-order linear multi-agent systems under deterministic and Markovian switching networks Journal Article In: International Journal of Systems Science, vol. 46, no. 10, pp. 1790-1799, 2013, ISSN: 0020-7721. |
2012 |
Disc Margins of the Discrete-time LQR and its Application to Consensus Problem Journal Article In: International Journal of Systems Science , vol. 43, no. 10, pp. 1891-1900, 2012. |
2010 |
Reduced-order Consensus Controllers for Output-coupled SISO Linear Systems Journal Article In: International Journal of Control, Automation and Systems, vol. 8, no. 6, pp. 1356-1363, 2010, ISBN: 1598-6446. |
0000 |
Initialization-free Algorithm for Discrete-time Dynamic Average Consensus and Its Application to Distributed Optimization Proceedings Article In: International Conference on Control, Automation and Systems (ICCAS 2022), Institute of Control, Robotics and Systems, 0000. |