Runtime Model Compliance Monitors for Cyber-Physical Systems
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Solution Overview
Problem
Cyber-physical systems (CPS) face challenges in ensuring safety due to deviations between real-world systems and their models, as formal verification assumes ideal conditions that may not reflect actual system behavior, leading to potential safety risks.
Innovation Solution
The ModelPlex method uses theorem proving with sound proof rules to synthesize monitors that verify compliance of system executions with models, initiating fail-safe actions when deviations occur, ensuring safety by predicting and mitigating risks through bounded deviation assumptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If formal verification uses ideal-world models with strong assumptions, then verification results are mathematically sound and safe, but the models deviate from real system behavior reducing validation reliability
Solution Approach 1:
The patent introduces runtime monitors as intermediary components that check whether actual system behavior conforms to the verified model. These monitors act as mediators between the ideal model and real system, validating that deviations remain within acceptable bounds and ensuring verification results transfer to the actual system.
Solution Approach 2:
The patent performs preliminary model verification under ideal assumptions to establish safety guarantees, then uses runtime monitors to check conformity in advance before safety violations occur. This two-stage approach ensures that if the system behaves according to the model, the verified safety properties hold.
2Productivity
If models are simplified for tractability and real-time computation, then prediction and optimization become feasible, but the models make unrealistic assumptions about system behavior reducing validation accuracy
Solution Approach 1:
The patent implements runtime monitors that continuously monitor actual system behavior and compare it against model predictions. This feedback mechanism allows the system to detect when simplified model assumptions violate real behavior patterns, enabling corrective actions while maintaining real-time computation efficiency.
3Reliability
If runtime validation checks system compliance with models continuously, then safety deviations are detected early, but computational overhead and system complexity increase
Solution Approach 1:
The patent segments the validation task into separate runtime monitors that independently check specific model assumptions and system properties. Each monitor handles a specific aspect of compliance checking, making the overall system more manageable and less complex while maintaining comprehensive safety validation.
Data Source
AI summary
A method for ensuring that verification results about models apply to cyber-physical systems (CPS) implementations is presented. The invention provides correctness guarantees for CPS executions at runtime. Offline verification of CPS models are combined with runtime validation of system executions for compliance with the model. The invention ensures that the verification results obtained for the model apply to the actual system runs by monitoring the behavior of the world for compliance with the model, assuming the system dynamics deviation is bounded. If, at some point, the observed behavior no longer complies with the model, such that offline verification results no longer apply, provably safe fallback actions are initiated. The invention includes a systematic technique to synthesize provably correct monitors automatically from CPS proofs in differential dynamic logic.