Resilient networking and cyber attack detection in cyber-physical systems

Abstract

The threats on cyber-physical system have changed much into a level of sophistication that elude the traditional security and protection methods. A paradigm shift is necessary to incorporate a proactive approach on top the reactive protection methods employed in dealing with the evolving threats. This work addresses a proactive and reactive approaches to the cyber security of a formation flying UAVs. In the proactive approach, resilient formation control of UAVs in the presence of non-cooperative (defective or malicious) UAVs are presented. The problem of network resilient consensus in the presence of misbehaving nodes based on local information is dealt with fault-tolerant consensus algorithm. In the proposed framework, a graph-theoretic property of network robustness conveying the notion of a direct information exchange between two sets of UAVs in the network is introduced to analyze the behavior and convergence of the distributed consensus algorithm. A distributed control policy is developed to maintain the network connectivity threshold to satisfy the topological requirement put forward for the resiliency of the consensus algorithm. The reactive approach deals with attack/fault detection and isolation of the compromised UAV in the network. In the multi-agent formation control, fault detection and Isolation (FDI) in control systems theory is used to detect and isolate the malicious agents using only local information. In this aspect, a bank of Unknown Input Observer (UIO) based distributed fault detection schemes, along with a rule based on residuals generated using the bank of UIOs, are proposed to detect the attacks and to identify the compromised UAV in the formation. Furthermore, an algorithm is developed to remove the faulty UAV from the network and isolate the compromised UAV once an attack is detected, while maintaining the flight formation with a missing UAV node. Various numerical examples are presented to show the applicability of both proactive and reactive approach used in deal with the cyber attack treat on a formation flying UAVs.