Causality for Cyber-Physical Systems

TL;DR

This paper introduces a formal causality theory tailored for cyber-physical systems, extending existing models to handle continuous dynamics, and provides an analysis technique to identify causes of failures in such systems.

Contribution

It extends Halpern and Pearl's causality theory to continuous cyber-physical systems and develops an efficient search-based analysis method with practical implementation.

Findings

Successfully identified causes of faults in case studies

Effective in analyzing continuous trajectories of failures

Demonstrated applicability on benchmark systems

Abstract

We present a formal theory for analysing causality in cyber-physical systems. To this end, we extend the theory of actual causality by Halpern and Pearl to cope with the continuous nature of cyber-physical systems. Based on our theory, we develop an analysis technique that is used to uncover the causes for examples of failures resulting from verification, which are represented as continuous trajectories. We develop a search-based technique to efficiently produce such causes and provide an implementation for such a technique. Moreover, we apply our solution to case studies (a suspension system and a connected platoon) and benchmark systems to evaluate its effectiveness; in the experiment, we show that we were able to detect causes for inserted faults.