A Real-Time Operating System for Physical and Logical Time-Triggered Distributed Computing
Koki Takado, Takanori Yokoyama, Myungryun Yoo · 2024
The paper introduces a real-time operating system (RTOS) for physical and logical time-triggered distributed computing, which is designed for cyber-physical systems with communication time fluctuations. Input/output tasks perform physical time-triggered processing, where the tasks are periodically activated synchronized with physical time. They are managed using fixed priority scheduling, assigning high priorities to minimize variations. Computation tasks, on the other hand, perform logical time-triggered processing, where the tasks are activated asynchronously upon receiving messages and managed through earliest deadline first scheduling, utilizing logical deadlines to enhance response times. Aperiodic tasks are also supported and managed by the total bandwidth server that can reduce their response time. The RTOS also provides shared resource management functionalities, leveraging the immediate priority ceiling protocol and the deadline floor protocol with deadline inheritance. These protocols manage resources shared by tasks governed by various scheduling policies. We have developed the RTOS by extending an AUTOSAR OS, a standard RTOS for automotive control. Performance evaluations indicate that the extension's overhead is acceptable.