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arXiv 1007.2738math.OCcs.SYeess.SY
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不可靠网络中的共识计算:系统论方法

Consensus Computation in Unreliable Networks: A System Theoretic Approach

University of California, Santa Barbara(加州大学圣塔芭芭拉分校);Centro I. R. “E. Piaggio”, Università di Pisa(比萨大学 E. Piaggio 中心)

Fabio Pasqualetti, Antonio Bicchi, Francesco Bullo

AI总结:

针对线性共识网络中行为异常代理的检测与识别问题,采用未知输入系统理论框架,给出了可检测与可识别的条件、最坏情况界限及三种算法。

摘要:

本文解决了确保线性共识网络中可信计算的问题。该问题的解决方案与多智能体系统中的若干任务相关,包括运动协调、时钟同步和协同估计。在线性共识网络中,我们允许存在行为异常的代理,其行为偏离名义共识演化。我们将异常行为建模为影响网络的未知且不可测输入,并将异常检测与识别问题转化为未知输入系统理论框架。我们考虑两种极端情况的异常代理,即故障(非合谋)代理和恶意(拜占庭)代理。首先,我们刻画了允许异常代理影响共识网络同时不被某些观察代理检测和/或识别的输入集合。其次,我们给出了可检测和可识别的并发故障或恶意代理数量的最坏情况界限。具体而言,对于k个恶意(分别地,故障)代理能够被每个行为正常的代理一般性地检测和识别,共识网络需要是2k+1(分别地,k+1)连通的。第三,我们量化了不可检测输入对最终共识值的影响。第四,我们设计了三种检测和识别异常代理的算法。第一种和第二种算法应用故障检测技术,如果每个代理可获得网络的全局知识,则能够实现完全检测和识别,但计算成本高。第三种算法旨在利用网络中弱互连子部分的存在,提供对行为偏差超过某个阈值的异常代理的局部检测和识别,该阈值根据互连结构量化。

英文摘要:

This work addresses the problem of ensuring trustworthy computation in a linear consensus network. A solution to this problem is relevant for several tasks in multi-agent systems including motion coordination, clock synchronization, and cooperative estimation. In a linear consensus network, we allow for the presence of misbehaving agents, whose behavior deviate from the nominal consensus evolution. We model misbehaviors as unknown and unmeasurable inputs affecting the network, and we cast the misbehavior detection and identification problem into an unknown-input system theoretic framework. We consider two extreme cases of misbehaving agents, namely faulty (non-colluding) and malicious (Byzantine) agents. First, we characterize the set of inputs that allow misbehaving agents to affect the consensus network while remaining undetected and/or unidentified from certain observing agents. Second, we provide worst-case bounds for the number of concurrent faulty or malicious agents that can be detected and identified. Precisely, the consensus network needs to be 2k+1 (resp. k+1) connected for k malicious (resp. faulty) agents to be generically detectable and identifiable by every well behaving agent. Third, we quantify the effect of undetectable inputs on the final consensus value. Fourth, we design three algorithms to detect and identify misbehaving agents. The first and the second algorithm apply fault detection techniques, and affords complete detection and identification if global knowledge of the network is available to each agent, at a high computational cost. The third algorithm is designed to exploit the presence in the network of weakly interconnected subparts, and provides local detection and identification of misbehaving agents whose behavior deviates more than a threshold, which is quantified in terms of the interconnection structure.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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