3 research outputs found
Asynchronous Byzantine Approximate Consensus in Directed Networks
In this work, we study the approximate consensus problem in asynchronous
message-passing networks where some nodes may become Byzantine faulty. We
answer an open problem raised by Tseng and Vaidya, 2012, proposing the first
algorithm of optimal resilience for directed networks. Interestingly, our
results show that the tight condition on the underlying communication networks
for asynchronous Byzantine approximate consensus coincides with the tight
condition for synchronous Byzantine exact consensus. Our results can be viewed
as a non-trivial generalization of the algorithm by Abraham et al., 2004, which
applies to the special case of complete networks. The tight condition and
techniques identified in the paper shed light on the fundamental properties for
solving approximate consensus in asynchronous directed networks.Comment: 25 pages, 2 figure
Advancements in Adversarially-Resilient Consensus and Safety-Critical Control for Multi-Agent Networks
The capabilities of and demand for complex autonomous multi-agent systems, including networks of unmanned aerial vehicles and mobile robots, are rapidly increasing in both research and industry settings. As the size and complexity of these systems increase, dealing with faults and failures becomes a crucial element that must be accounted for when performing control design. In addition, the last decade has witnessed an ever-accelerating proliferation of adversarial attacks on cyber-physical systems across the globe. In response to these challenges, recent years have seen an increased focus on resilience of multi-agent systems to faults and adversarial attacks. Broadly speaking, resilience refers to the ability of a system to accomplish control or performance objectives despite the presence of faults or attacks. Ensuring the resilience of cyber-physical systems is an interdisciplinary endeavor that can be tackled using a variety of methodologies. This dissertation approaches the resilience of such systems from a control-theoretic viewpoint and presents several novel advancements in resilient control methodologies. First, advancements in resilient consensus techniques are presented that allow normally-behaving agents to achieve state agreement in the presence of adversarial misinformation. Second, graph theoretic tools for constructing and analyzing the resilience of multi-agent networks are derived. Third, a method for resilient broadcasting vector-valued information from a set of leaders to a set of followers in the presence of adversarial misinformation is presented, and these results are applied to the problem of propagating entire knowledge of time-varying Bezier-curve-based trajectories from leaders to followers. Finally, novel results are presented for guaranteeing safety preservation of heterogeneous control-affine multi-agent systems with sampled-data dynamics in the presence of adversarial agents.PHDAerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/168102/1/usevitch_1.pd