关键词: 硬实时, 控制系统, 编程模型, 时间可预测性, 逻辑执行时间, 服务体/执行流

Abstract: Both the function and finish time of an embedded real-time task affect the physical behavior of an embedded control system. Traditional process/thread model deals with timing indirectly with priorities, lacking timing semantics, so that the finish time of a task is of no predictability. Henzinger has come up with the LET（Logical Execution Time） model, which describes timing requirements clearly using coordinate timing semantic, however, it’s still based on process/thread model, which may introduce timing-unpredictability. By combining Servant/Exe-Flow Model and LET model. This paper presents a new time-predictable programming model, Timed SEFM, which uses refined SEFM model to deal with functionality and uses LET model to deal with timing. An implementation of intelligent car system is presented as a case study.

Key words: hard real-time, control system, programming model, time predictability, Logical Execution Time（LET）, servant/exe-flow