William Casbolt | Searcharxiv

arXiv2021

Optimal Control over Multiple Input Lossy Channels

The performance of control systems with input packet losses on the controller to plant communication channel is analysed. The main contribution of this work is a proof that linear optimal control systems operating with UDP-like communication protocols have a larger quadratic cost than the same systems operating with TCP-like protocols. The proof is derived for the general case of multidimensional and independent actuation communication channels. In doing so, our results extend previous work to systems with multiple distributed actuators. The difference in cost between two communication protocols is analysed, enabling the maximal difference between the two protocols to be quantified. Numerical examples are presented to highlight the difference in costs induced by the choice of communication protocol.

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arXiv2020

Denial of Service Attacks on Control Systems with Packet Loss

The performance of control systems with packet loss as a result of an attack over the actuation communication channel is analysed. The operator is assumed to monitor the state of the channel by measuring the average number of packet losses and an attack detection criteria is established based on the statistic. The performance of the attacker is measured in terms of the increase of the linear quadratic cost function of the operator subject to a given detection constraint. Within that setting, the optimal denial of service (DoS) attack strategy is formulated for UDP-like and TCP-like communication protocols. {For both communication protocols,} DoS attack constructions that are independent and identically distributed (IID) are compared to those that are non-stationary. The main contributions of this paper are (i) explicit characterisation of the expected cost increase of the optimal attack constructions and the associated packet loss parameter for the IID case, (ii) proof, by example, that non-stationary random attacks outperform IID attacks in the presence of detection constraints.

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