Towards a formal methodology of deterministic scheduling for real-time flight safety critical software design

The technique of static cyclic scheduling offers an optimum implementation strategy for the real-time flight safety critical software designer. Not only does this technique relieve operating processors of the need to perform dynamic scheduling tasks, a also provides high levels of temporal determinism, pre-code verification and test coverage. However, without an explicit analytical understanding of the relationship(s) between timing/sequencing requirements and compliant schedule design, the technique will continue to resist the advantages of auto-generation and formal verification; the first leading to greater efficiency in the software development process, and the second enabling pre-coding formal verification techniques. A brief outline is presented of the formal theories of scheduling design compliance currently under investigation by Lucas Aerospace (Engineering Software), together with a description of how such “formal theories” are exploited within procedurally closed scheduling development environments