Anomaly Detection Under Multiplicative Noise Model Uncertainty

TL;DR

This paper introduces a novel anomaly detection method for cyber-physical systems that accounts for model uncertainty using a multiplicative noise framework, improving detection robustness.

Contribution

It extends existing anomaly detection techniques by incorporating multiplicative noise to handle model uncertainty, using a multiplicative noise LQG compensator.

Findings

Effective detection of anomalies under model uncertainty

Validation through numerical simulations shows improved robustness

Extends state-of-the-art anomaly detection methods

Abstract

State estimators are crucial components of anomaly detectors that are used to monitor cyber-physical systems. Many frequently-used state estimators are susceptible to model risk as they rely critically on the availability of an accurate state-space model. Modeling errors make it more difficult to distinguish whether deviations from expected behavior are due to anomalies or simply a lack of knowledge about the system dynamics. In this research, we account for model uncertainty through a multiplicative noise framework. Specifically, we propose to use the multiplicative noise LQG based compensator in this setting to hedge against the model uncertainty risk. The size of the residual from the estimator can then be compared against a threshold to detect anomalies. Finally, the proposed detector is validated using numerical simulations. Extension of state-of-the-art anomaly detection in cyber-physical systems to handle model uncertainty represents the main novel contribution of the present work.