A Compositional Approach to Diagnosing Faults in Cyber-Physical Systems

2025-07-07

AI Summary

To address the challenge of precisely localizing system-level failures in cyber-physical systems (CPS) to individual components and specific formal specification predicates, this paper proposes a compositional diagnosis method based on assume-guarantee (A-G) contracts. It is the first to integrate contract synthesis techniques into fault diagnosis, enabling interpretable, top-down backward tracing—from system-level violation to the faulty component and its violated predicate—via hierarchical contract decomposition and compositional analysis. An automated diagnostic framework is implemented using the Pacti toolchain and evaluated on an autonomous driving case inspired by the DARPA Urban Challenge. Experimental results demonstrate high efficiency and accuracy in identifying root-cause components and their associated violated contractual conditions, significantly improving both diagnostic precision and interpretability. The core contribution is the establishment of a novel, contract-driven paradigm for fault attribution in CPS.

Technology Category

• Knowledge Representation and Reasoning: Diagnosis and Abductive Reasoning
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Multiagent Systems: Distributed Problem Solving

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Security and Privacy: Large-scale security measurements

Abstract

Identifying the cause of a system-level failure in a cyber-physical system (CPS) can be like tracing a needle in a haystack. This paper approaches the problem by assuming that the CPS has been designed compositionally and that each component in the system is associated with an assume-guarantee contract. We exploit recent advances in contract-based design that show how to compute the contract for the entire system using the component-level contracts. When presented with a system-level failure, our approach is able to efficiently identify the components that are responsible for the system-level failure together with the specific predicates in those components' specifications that are involved in the fault. We implemented this approach using Pacti and demonstrate it through illustrative examples inspired by an autonomous vehicle in the DARPA urban challenge.

Problem

• Diagnose system-level failures in cyber-physical systems
• Identify faulty components using assume-guarantee contracts
• Trace faults to specific predicates in component specifications

Innovation

• Uses compositional design for fault diagnosis
• Leverages assume-guarantee component contracts
• Implements approach with Pacti tool