A Framework for Runtime Safety of Industrial Control Systems Through Runtime Verification

Ensuring the safety of complex industrial control systems (ICS) cannot be fully achieved during the design and development phases. Many uncertainties and unknowns only become apparent during real-world operation, especially in the context of Industry 4.0, where ICS integrate increasing characteristics of cyber-physical systems (CPS), such as openness and connectivity. Runtime verification (RV) is extensively employed to guarantee the runtime safety of systems. However, current RV methods face substantial challenges in ICS, particularly due to extensive device heterogeneity, intricate real-time constraints, and the need for coordinating multiple controllers. In this article, we propose a novel framework that incorporates stream-based RV to ensure the runtime safety of ICS. By leveraging a communication bridge based on the open platform communications unified architecture (OPC UA) standard, our framework achieves platform compatibility. This framework, coupled with its nonintrusive verification feature, is well-suited for scenarios involving heterogeneous devices and collaborative controllers. Additionally, stream-based formal specification captures complex time-sensitive constraints, such as real-time synchronizations involving various signals, including triggering, duration, and timeout. To further enhance safety, the framework offers online correction strategies for addressing runtime violations, aiming to preserve or restore system safety. Experimental results from general case studies demonstrate that our approach surpasses existing methods in managing device heterogeneity, complex real-time constraints, and multicontroller cooperation scenarios.