Shield Synthesis for Real: Enforcing Safety in Cyber-Physical Systems
This addresses safety-critical issues in cyber-physical systems, such as automotive controls, by extending shield synthesis to handle real-valued signals, which is an incremental advance over existing Boolean methods.
The paper tackles the problem of enforcing safety in cyber-physical systems with real-valued signals by synthesizing a runtime enforcer called a shield, which corrects violations instantaneously to prevent erroneous outputs. The method solves realizability and efficiency issues through static analysis and a two-player safety game, demonstrating effectiveness on applications like an automotive powertrain control system.
Cyber-physical systems are often safety-critical in that violations of safety properties may lead to catastrophes. We propose a method to enforce the safety of systems with real-valued signals by synthesizing a runtime enforcer called the shield. Whenever the system violates a property, the shield, composed with the system, makes correction instantaneously to ensure that no erroneous output is generated by the combined system. While techniques for synthesizing Boolean shields are well understood, they do not handle real-valued signals ubiquitous in cyber-physical systems, meaning corrections may be either unrealizable or inefficient to compute in the real domain. We solve the realizability and efficiency problems by statically analyzing the compatibility of predicates defined over real-valued signals, and using the analysis result to constrain a two-player safety game used to synthesize the shield. We have implemented the method and demonstrated its effectiveness and efficiency on a variety of applications, including an automotive powertrain control system.