Formal Verification of Adaptive Real-Time Systems by Extending Task Automata

Abstract: Recently, we have seen an increase in the deployment of safety critical embedded systems in rapidly changing environments, as well as requirement for on-site customizations and rapid adaptation. To address the extended range of requirements, adaptation mechanism are added to the systems to handle large number of situations appropriately. Although necessary, adaptations can cause inconsistent and unstable configurations that must be prevented for the embedded system to remain dependable and safe. Therefore, verifying the behavior of adaptive embedded systems during the design phase of the production process is highly desirable.A hard real time embedded system and its environment can be modeled using timed automata. Such model can describe the system at various levels of abstraction. In this thesis, we model the adaptive responses of a system in terms of tasks that are executed to handle changes in the environmental or internal parameters.Schedulability, a property that all tasks complete execution within their respective deadlines, is a key element in designing hard real-time embedded systems. A system that is unschedulable immediately compromises safety and hard real-time requirements and can cause fatal failure. Given specifications of all tasks in the system, we can model the system, an abstraction of the environment, and adaptive strategies to investigate whether the system retains safety properties, including schedulability, regardless of the changes in the environment and adaptations to those changes.