Narrow Results

Introducing a reputation mechanism to improve the practical Byzantine fault-tolerant algorithm (PBFT) can effectively increase the security of the system, but the lack of a proper reputation synchronization method can easily lead to malicious behaviors such as node reputation fraud. To solve the above problems, this paper proposes an improved PBFT algorithm (RS-PBFT) which can synchronize node reputation. Firstly, node types are distinguished by node behaviors. The node types represent node reputation status. Secondly, the management node, which summarizes node behavior, judges node type and synchronizes node reputation, is selected by voting method. Finally, the grouping idea is used to optimize the consistency protocol. The consensus between consensus groups is parallel. Furthermore, the consensus within consensus groups is co-dominated by multiple subgroup master nodes, which reduces the communication overhead and solves the problems such as the lack of limit of a single master node. The experimental results show that when the number of consensus nodes is 12, the throughput of RS-PBFT algorithm is 5.98 times that of PBFT algorithm. The consensus delay is reduced to 27.5% of PBFT algorithm, and the communication cost is reduced by 72.6%.

In this paper, group consensus of second-order multi-agent systems with nonlinear dynamics is investigated. First, we design the distributed protocols for achieving group consensus, in which the strengths of the interactions among the agents are enhanced through tuning the coupling strengths. Further, taking the difference of the edges among agents into account, edge-based distributed protocols through tuning coupling weights of a fraction of edges are designed. Remarkably, only the edges of spanning tree in each group are pinned and the coupling strengths or weights of pinned edges are enhanced according to the updated laws. Both the types of distributed protocols are proved analytically and verified by numerical illustrations.

This paper investigates group consensus for linear multi-agent systems with nonidentical dynamics. A novel adaptive event-triggered communication scheme is presented by using the stochastic sampling information, the event-triggered matrices and time-varying event-triggered parameters are introduced into event-triggered condition, where event-triggered parameters can be adjusted with the system dynamics evolving. The group consensus protocol is designed based on the neighboring agents information at event-triggered instants, then a new stochastic sampled-data dependent error model is constructed, some group consensus criteria in mean-square can be derived and the feedback matrices can also be obtained. Finally, two numerical examples are provided to illustrate the validity of the theoretical results.

This paper studies the group consensus problem in networks of multi-agent systems, in which the nonlinear dynamics of all agents are unknown and nonidentical. We assume that the unknown dynamics are linearly parameterized. Adaptive control method is adopted in the algorithm design. A novel algorithm is proposed for the multi-agent systems to reach group consensus via pinning control strategies, which only rely on the relative position information between neighboring agents. The stability and parameter convergence analysis are done based on Lyapunov theory, Barbalat's lemma, adaptive control theory and algebraic graph theory. Finally, a simulation example is given to validate our theoretical results.

In multi-criteria group decision-making, how to generate a consensus-based solution that is satisfactory to most of the decision makers, is always a critical research issue. In this paper, with consideration of the satisfaction levels of decision makers, a new group consensus reaching method with distributed preference relations (DPRs) is proposed to generate the consensus-based solution with high satisfaction level. In the proposed method, the consensus measurement of DPRs is constructed in terms of decision makers’ risk attitudes to help justify whether the predefined consensus requirement is satisfied. Afterwards, the satisfaction level of each decision maker on each criterion is constructed from the differences between assessments and rankings provided by decision makers and those aggregated by a group of decision makers. Based on the satisfaction levels of decision makers, a new feedback mechanism including identification rules and direction rules is designed to generate acceptable recommendations to decision makers who may need to modify their opinions. The modified opinions will help to generate the consensus-based solution that is satisfactory to most of the decision makers. To demonstrate the applicability and validity of the proposed consensus reaching method, a real case of evaluating safety performance of an enterprise is investigated.