Abstract: Flight control system is typical hard real-time system. Period design of tasks is the foundation in development of flight control system. For meeting functional and real-time requirements of flight control software, period design of task must be completed in incipient stage of system design. According to task functions, time constraints and design requirements, emphasis of every task must be separated. Based on task characteristic of flight control system, the time limit of every task in flight control software should be confirmed. The period of every task can be determined with all time constraints. The method has been used in programing of a specific project, and referenced in design of flight control software.

Key words: flight control software, periodic task, time constraints

摘要： 飞行控制系统是典型的硬实时系统，任务周期设计是飞行控制系统设计的基础。为了保证飞行控制软件满足实时性和功能性要求，在系统设计初期进行的任务周期设计首先需要根据任务功能、时限要求和设计指标的不同，区分每个任务周期设计的侧重点并进行分类；结合飞行控制软件中周期任务的特点，确定飞行控制软件中任务周期设计的所有时间约束；根据任务的所有的时间约束条件进行任务周期的设计。这种设计思路及方法已经在具体案例的设计中使用，其对于飞行控制软件的设计具有很好的参考意义。

关键词: 飞行控制软件, 周期任务, 时间约束