There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

This paper presents control and coordination algorithms for groups of vehicles. The focus is on autonomous vehicle networks performing distributed sensing tasks where each vehicle plays the role of a mobile tunable sensor. The paper proposes gradient descent algorithms for a class of utility functions which encode optimal coverage and sensing policies. The resulting closed-loop behavior is adaptive, distributed, asynchronous, and verifiably correct.

Coverage control for mobile sensing networks

Introduction to Mathematical Statistics. By R.V. Hogg and A. T. Craig. Pp. ix, 245. 47s. 1959. (The Macmillan Company, New York)

Networked control systems are spatially distributed systems in which the communication between sensors, actuators, and controllers occurs through a shared band-limited digital communication network. Several advantages of the network architectures include reduced system wiring, plug and play devices, increased system agility, and ease of system diagnosis and maintenance. Consequently, networked control is the current trend for industrial automation and has ever-increasing applications in a wide range of areas, such as smart grids, manufacturing systems, process control, automobiles, automated highway systems, and unmanned aerial vehicles. The modelling, analysis, and control of networked control systems have received considerable attention in the last two decades. The &#x2018 control over networks &#x2019 is one of the key research directions for networked control systems. This paper aims at presenting a survey of trends and techniques in networked control systems from the perspective of &#x2018 control over networks &#x2019 , providing a snapshot of five control issues: sampled-data control, quantization control, networked control, event-triggered control, and security control. Some challenging issues are suggested to direct the future research.

Networked control systems: a survey of trends and techniques

Monitoring the “physics” of cyber-physical systems to detect attacks is a growing area of research. In its basic form, a security monitor creates time-series models of sensor readings for an industrial control system and identifies anomalies in these measurements to identify potentially false control commands or false sensor readings. In this article, we review previous work on physics-based anomaly detection based on a unified taxonomy that allows us to identify limitations and unexplored challenges and to propose new solutions.

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A Survey of Physics-Based Attack Detection in Cyber-Physical Systems

Security of Cyber-Physical Systems (CPS) against cyber attacks is an important yet challenging problem. Since most cyber attacks happen in erratic ways, it is difficult to describe them systematically. In this paper, instead of identifying a specific cyber attack model, we are focused on analyzing the system's response during cyber attacks. Deception attacks (or false data injection attacks), which are performed by tampering with system components or data, are not of particular concern if they can be easily detected by the system's monitoring system. However, intelligent cyber attackers can avoid being detected by the monitoring system by carefully design cyber attacks. Our main objective is to investigate the performance of such stealthy deception attacks from the system's perspective. We investigate three kinds of stealthy deception attacks according to the attacker's ability to compromise the system. Based on the information about the dynamics of the system and existing hypothesis testing algorithms, we derive the necessary and sufficient conditions under which the attacker could perform each kind of attack without being detected. In the end, we illustrate the threat of these cyber attacks using an Unmanned Aerial Vehicle (UAV) navigation example.

Security analysis for Cyber-Physical Systems against stealthy deception attacks

Cyber security has emerged as one of the most important issues in unmanned aerial systems for which the functionality heavily relies on onboard automation and intervehicle communications. In this paper, potential cyber threats and vulnerabilities in the unmanned aerial system’s state estimator to stealthy cyber attacks are identified, which can avoid being detected by the monitoring system. Specifically, this paper investigates the worst stealthy cyber attack that can maximize the state estimation error of the unmanned aerial system’s state estimator while not being detected. First, the condition that the system is vulnerable to the stealthy cyber attacks is derived, and then an analytical method is provided to identify the worst stealthy cyber attack. The proposed cyber attack analysis methods are demonstrated with illustrative examples of an onboard unmanned aerial system navigation system and an unmanned aerial system tracking application.

Analysis and Design of Stealthy Cyber Attacks on Unmanned Aerial Systems

This technical note proposes an algorithm to assess the safety of the cyber-physical system (CPS) in the presence of cyber attacks, which can be designed intelligently to avoid the detection. The main idea is based on the reachability analysis that computes the reachable set of CPS states possibly reached by all potential cyber attacks regardless of their detection. The reachable set computation typically demands a large computation cost and has mostly relied on the (over) approximation techniques. However, our algorithm analytically derives the exact reachable set solution and further establishes a recursive computation structure that can perform in the real-time CPS operation. This can significantly enhance the quality of the online safety assessment, enabling more reliable, less conservative, and computationally efficient process.

Reachability Analysis for Safety Assurance of Cyber-Physical Systems Against Cyber Attacks

This study considers robust controller design for cyber–physical systems (CPSs) subject to cyber attacks. While previous studies have investigated secure control by assuming specific attack strategies, in this study the authors propose a robust hybrid control scheme containing multiple sub-controllers, each matched to a different type of cyber attack. A system using this control scheme is able to adapt its behaviour to various cyber attacks (including those which have not been specifically addressed in the sub-controller designs) by switching sub-controllers to achieve the best performance. They propose a method for designing the secure switching logic to counter possible cyber attacks and to mathematically verify the system's performance and stability as well. The performance of the proposed control scheme is demonstrated by the hybrid H 2–H ∞ controller applied to a CPS subject to cyber attacks.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-cta.2014.1013

Cyber attack mitigation for cyber–physical systems: hybrid system approach to controller design

As unmanned aircraft systems become an increasingly integral part of a wide range of applications, ensuring the security of these systems against malicious cyber attacks is a very important concern. To address this problem, this paper considers a controls domain approach extending beyond the computing resources of the unmanned aircraft system to include the underlying physical behavior of the compromised system, successfully complementing the traditional computer security architecture. Specifically, the focus is on the safety analysis of an unmanned aircraft system in the presence of stealthy cyber attacks, which can be designed intelligently to avoid detection. First, the system condition that confines the stealthy attacker’s capability is derived. Then, a real-time safety assessment algorithm is developed based on a reachability analysis. Compared to the existing research, the present algorithm analytically derives the exact reachable set, enabling more reliable and computationally efficient safety asse...

Cheolhyeon Kwon

Papers

Security analysis for Cyber-Physical Systems against stealthy deception attacks

Analysis and Design of Stealthy Cyber Attacks on Unmanned Aerial Systems

Reachability Analysis for Safety Assurance of Cyber-Physical Systems Against Cyber Attacks

Cyber attack mitigation for cyber–physical systems: hybrid system approach to controller design

Real-Time Safety Assessment of Unmanned Aircraft Systems Against Stealthy Cyber Attacks