Across diverse applications including healthcare monitoring, transportation, and electrical power systems, Cyber-Physical Systems (CPS) integrate continuous and discrete domains to deliver smart, safe, efficient, and responsive infrastructures. In order to ensure the safety and robust performance, a system should guarantee that its timing properties/specifications will be satisfied. Therefore, the timing specifications for a safety-critical application must be expressed and managed in a formal language such that test codes can efficiently verify proper operation. This is accomplished through temporal logic. By expressing the system timing specifications in such a formalism, it becomes possible to have precise system description, right design, accurate implementation, and valid verification process.
Researchers at Arizona State University have developed a new timing framework for cyber-physical systems called Timestamp Temporal Logic (TTL). TTL comprises a formalism, methodology, and monitoring tool to express and verifying temporal behavior of CPS using an efficient approach for monitoring system temporal specifications. TTL supports temporal properties on both event-based and value-based constraints while featuring intuitive, simple syntax as well as ease of implementation and minimum hardware requirements. Whereas the existing expression temporal frameworks store signal values at associated sampling frequencies, TTL monitoring uses only event timestamps thereby reducing system memory requirements. Such a succinct and efficient framework is required throughout the entire development stack of CPS. By using the TTL syntax/language, the system description is clear for both utilizers and technical groups. TTL framework can be utilized as the methodology to monitor the system operation and in case of violation notify the operating device to have graceful degradation or even stopping the running processes in catastrophic situations. Moreover, having a monitoring system beside the main operating CPS makes the system robust against the faulty equipment since the monitoring is able to point out the faults based on the monitored timing specifications. As a fact, regarding the entire CPS development, TTL is the solution to manufacture CPS based on the required behavior and according to the safety features.
Safety-critical autonomous applications
• Safety-critical systems
• Cyber-physical systems
Benefits and Advantages
• Greatly simplifies timing expressions, leading to more intuitive and efficient testing
• TTL covers all STL operators in addition to others
• Reduced memory requirement compared to STL allows online analysis of timing constraints of potentially large-scale distributed CPSs