Abstract: In the open real-time embedded environment，different kinds of real-time tasks coexist in one system.This brings new requirements and challenges to the real-time scheduling mechanism.A formal self-adaptive scheduling model for open real-time embedded system is presented in this paper，which comprises four key components：accept control，resource management，scheduling server and adaptive control.To guarantee the schedulability in the open environment，this model only accepts the task whose computing bandwidth requirement is no higher than the system’s spare one.In this model，the scheduling server components provide concurrent scheduling mechanism for multi-constraint tasks，and each of them is assigned to a bandwidth-independent computing bandwidth and has its specific scheduling policy to schedule its own task queue.To adapt to the change in the open environment，the adaptive control tries to tune the real-time priority so as to make full use of the system computing capability.This model has been used in an airborne system.Compared with other system，it actually improved the schedulability of system and systematic stability.

Key words: open system, embedded, real-time, self-adaptive, scheduling model

摘要： 开放式实时嵌入式系统中多类型实时任务并存和资源受限的情况给实时调度机制带来了新的需求和挑战。通过引入准入控制、资源管理、调度服务器、自适应调节机制等，提出了一个形式化的自适应调度模型。它能适应开放计算环境的不确定性，有控制地接受不同类型任务的运行;可根据系统资源和任务需求的最新变换情况计算带宽变化，自适应地调节任务的优先等级，使得系统运行在最优的实时性能上;该模型在某航空机载系统设计中得到了实际应用，同其它类似系统相比，该模型的应用提高了系统的调度性和系统稳定性。

关键词: 开放式系统, 嵌入式, 实时, 自适应, 调度模型