• Journal of Institute of Control, Robotics and Systems
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• v.20 no.12
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• pp.1225-1230
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• 2014

This paper investigates the group average-consensus and group formation-consensus problems for first-order multi-agent systems. The control protocol for group consensus is designed by considering the positive adjacency elements. Since each intra-group Laplacian matrix cannot be satisfied with the in-degree balance because of the positive adjacency elements between groups, we decompose the Laplacian matrix into an intra-group Laplacian matrix and an inter-group Laplacian matrix. Moreover, average matrices are used in the control protocol to analyze the stability of multi-agent systems with a fixed and undirected communication topology. Using the graph theory and the Lyapunov functional, stability analysis is performed for group average-consensus and group formation-consensus, respectively. Finally, some simulation results are presented to validate the effectiveness of the proposed control protocol for group consensus.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.5
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• pp.526-532
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• 2014

In this paper, we present and analyze a LQ (Linear Quadratic) inverse optimal state-consensus protocol for continuous-time multi-agent systems with undirected graph topology. By Lyapunov analysis of the state-consensus error dynamics, we show the sufficient conditions on the algebraic connectivity of the graph to guarantee LQ inverse optimality and closed-loop stability. A more relaxed stability condition is also provided in terms of the algebraic connectivity. Finally, a formation control protocol for multiple mobile robots is proposed based on the target LQ inverse optimal consensus protocol, and the simulation results are provided to verify the performance of the proposed LQ inverse formation control method.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.5
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• pp.434-441
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• 2015

In this paper, we propose an inverse optimal distributed protocol for the formation and velocity consensus of nonholonomic mobile robots. The communication among mobile robots is described by a simple undirected graph, and the mobile robots' kinematics are considered. The group of mobile robots driven by the proposed protocols asymptotically achieves the desired formation and group velocity in an inverse optimal fashion. The design of the protocols is based on dynamic feedback linearization and the proposed linear quadratic (LQ) inverse optimal second-order consensus protocol. A numerical simulation is given to verify the effectiveness of the proposed scheme.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.41-46
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• 2019

Recently, the Byzantine Fault Tolerance(BFT) family of consensus algorithms has been attracting attention as the problems of the Proof-of-work (PoW) blockchain consensus algorithms result in energy waste and lack of scalability. One of the great features of the PBFT family consensus algorithms is the formation of a set of validators and consensus within them. In this paper, we compared and analyzed the scalability, targeted attackability, and civil attackability of Algorand, Stellar, and EOS validator set formation methods among BFT family consensus algorithms. Also, we found the problems of each verifier formation method through data analysis, and the consensus algorithms showed that the centralization phenomenon that the few powerful nodes dominate the whole system in common.

• The International Journal of Costume Culture
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• v.9 no.2
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• pp.104-112
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• 2006

The studies on impression formation usually have focused on the effect of certain appearance features which elevates perceptual evaluation. This study tried to find out whether there is a consensus on impression formation between the perceived person and the perceiver and if the gender is any significant variable to cast any difference on the impression evaluation. Seven photos of voluntary students in ppt file were projected to 143 students attending a university psychology class and were subjected to a impression evaluation questionnaire consisting of 28 adjective scales. The analysis of result revealed: 1) There was a significant difference between the impression evaluation scores of the perceivers and the perceived; the self evaluation of the perceived person was higher than the perceivers' evaluation. 2) There was also a significant evaluation score difference between the genders of the perceivers; the female perceivers rated the stimuli higher than the male perceivers. There was no interaction effect between the genders of the perceivers and the perceived.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.10
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• pp.988-995
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• 2008

A consensus-based feedback linearization method is proposed to maintain a specified time-varying geometric configuration for formation flying of multiple autonomous vehicles. In this approach, there exists no explicit leader in the team, and the proposed control strategy requires only the local neighbor-to-neighbor information between vehicles. The information flow topology between the vehicles is defined by Graph Laplacian matrix, and the formation flying can be achieved by the proposed feedback linearization with consensus algorithm. The stability analysis of the proposed controller is also performed via eigenvalue analysis for the closed-looop system. Numerical simulation is performed for rotary-wing type micro aerial vehicles to validate the performance of the proposed controller.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1080-1084
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• 2014

This paper addresses a design technique for formation tracking controllers of discrete-time Takagi-Sugeno fuzzy multi-agent systems based on consensus. The interconnection topology among the agents is expressed as a digraph. The design condition is represented in terms of linear matrix inequalities. Numerical example demonstrates the effectiveness of the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.5
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• pp.439-444
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• 2012

In this study, we address the formation control problem of coupled unicycle-type mobile robots, each of which can interact with its neighboring robots by communicating their position outputs. Each communication link between two mobile robots is assumed to be established according to the given time-varying interconnection topology that switches within a finite set of connected fixed undirected networks and has a non-vanishing dwell time. Under this setup, we propose a distributed formation control algorithm by using the dynamics extension and feedback linearization methods, and by employing a consensus algorithm for linear multi-agent systems which provides arbitrary fast convergence rate to the agreement of the multi-agent system. Finally, the proposed result is demonstrated through a computer simulation.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.2
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• pp.103-111
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• 2023

Consensus, that aims to converge the states of agents to the same states through information exchanges between agents, has been widely studied to control the multi-agent systems. In real systems, the measurement variables of each agent may be different, the loss of information across communication may occur, and the different networks for each state may need to be constructed for safety. Moreover, the input saturation and the disturbances in the system may cause instability. Therefore, this paper studies the PID(Proportional-Integral-Derivative)-based consensus control to achieve the swarm behavior of the multi-agent systems considering the heterogeneous state information, the input saturations, and the disturbances. Specifically, we consider the multiple follower agents and the single leader agent modeled by the second-order systems, and investigate the conditions to achieve the consensus based on the stability of the error system. It is confirmed that the proposed algorithm can achieve the consensus if only the connectivity of the position graph is guaranteed. Moreover, by extending the consensus algorithm, we study the formation control problem for the multi-agent systems. Finally, the validity of the proposed algorithm was verified through the simulations.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.5
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• pp.398-409
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• 2013

This paper provides an overview of distance-based formation control. Firstly, in this paper, we introduce preliminary background materials that are used in defining the distance-based formation control. Then, based on the preliminary background, we briefly review main results developed thus far in this field. Lastly, we provide some issues that need to be studied further in future works.