arXiv subjects

Chong Jin Ong

Publications and source records attributed to Chong Jin Ong.

5 recordsLinked to original sources

arXiv2026

Output Consensus on Periodic References for Constrained Multi-agent Systems Under a Switching Network

This work addresses the output consensus problem of constrained heterogeneous multi-agent systems under a switching network with potential communication delays, where outputs are periodic and characterized by an exosystem. Since periodic references have more complex dynamics, it is more challenging to track periodic references and achieve consensus on them. In this paper, a model predictive control method incorporating an artificial reference and a modified cost function is proposed to track periodic references, which maintains recursive feasibility even when references switch. Moreover, consensus protocols are proposed to achieve consensus on periodic references in different scenarios, in which global information such as the set of globally admissible references and the global time index are not involved. Theoretical analysis proves that constrained output consensus is asymptotically achieved with the proposed algorithm as the references of each agent converge and agents track their references while maintaining constraint satisfaction. Finally, numerical examples are provided to verify the effectiveness of the proposed algorithm.

eess.SY↗

arXiv2024

Enabling microrobotic chemotaxis via reset-free hierarchical reinforcement learning

Microorganisms have evolved diverse strategies to propel in viscous fluids, navigate complex environments, and exhibit taxis in response to stimuli. This has inspired the development of synthetic microrobots, where machine learning (ML) is playing an increasingly important role. Can ML endow these robots with intelligence resembling that developed by their natural counterparts over evolutionary timelines? Here, we demonstrate chemotactic navigation of a multi-link articulated microrobot using two-level hierarchical reinforcement learning (RL). The lower-level RL allows the robot -- featuring either a chain or ring topology -- to acquire topology-specific swimming gaits: wave propagation characteristic of flagella or body oscillation akin to an ameboid. Such flagellar and ameboid microswimmers, further enabled by the higher-level RL, accomplish chemotactic navigation in prototypical biologically-relevant scenarios that feature conflicting chemoattractants, pursuing a swimming bacterial mimic, steering in vortical flows, and squeezing through tight constrictions. Additionally, we achieve reset-free, partially observable RL, where the robot observes only its joint angles and local scalar quantities. This advancement illuminates solutions for overcoming the persistent challenges of manual resets and partial observability in real-world microrobotic RL.

cond-mat.soft↗

arXiv2022

Consensus of Homogeneous Agents with General Linear Dynamics under Switching Communication Networks

This work addresses the synchronization/consensus problem of identical multi-agent system (MAS) where the agents' dynamics are linear and the communication network is arbitrarily switching among connected topologies. The approach uses a gain matrix of a special structure in a dynamic compensator for each agent. Under reasonable conditions, the approach ensures that consensus is reached when the gain is sufficiently large. This result holds for general linear systems including the case where agents have repeated unstable eigenvalues. The proposed controller structure can be seen as a special case of the existing MAS controller structures but offers consensus conditions that are simpler than existing results, especially for the case when the network is switching among connected graphs. The works shows its application to three communication settings: fixed graph, switching among undirected and connected graphs and switching among directed and connected graphs. An example is provided to illustrate the results.

eess.SY↗

arXiv2021

Consensus of Multi-agent System via Constrained Invariant Set of a class of Unstable System

This work shows an approach to achieve output consensus among heterogeneous agents in a multi-agent environment where each agent is subject to input constraints. The communication among agents is described by a time-varying directed/undirected graph. The approach is based on the well-known Internal Model Principle which uses an unstable reference system. One main contribution of this work is the characterization of the maximal constraint admissible invariant set (MCAI) for the combined agent-reference system. Typically, MCAI sets do not exist for unstable system. This work shows that for an important class of agent-reference system that is unstable, MCAI exists and can be computed. This MCAI set is used in a Reference Governor approach, combined with a projected consensus algorithm, to achieve output consensus of all agents while satisfying constraints of each. Examples are provided to illustrate the approach.

eess.SY↗

arXiv2017

Speeding up finite-time consensus via minimal polynomial of a weighted graph - a numerical approach

Reaching consensus among states of a multi-agent system is a key requirement for many distributed control/optimization problems. Such a consensus is often achieved using the standard Laplacian matrix (for continuous system) or Perron matrix (for discrete-time system). Recent interest in speeding up consensus sees the development of finite-time consensus algorithms. This work proposes an approach to speed up finite-time consensus algorithm using the weights of a weighted Laplacian matrix. The approach is an iterative procedure that finds a low-order minimal polynomial that is consistent with the topology of the underlying graph. In general, the lowest-order minimal polynomial achievable for a network system is an open research problem. This work proposes a numerical approach that searches for the lowest order minimal polynomial via a rank minimization problem using a two-step approach: the first being an optimization problem involving the nuclear norm and the second a correction step. Several examples are provided to illustrate the effectiveness of the approach.

eess.SY↗