Abstract: In real-time control system，there are some uncertain factors caused by concurrency and resource sharing，which lead to uncertion varitions of periodic activities running time，so the real-time control system becomes unstable.In order to ensure high performance and predictability，reducing jitter is very important in such system.By introducing deadline reduction factor，this article determines a new relative deadline，thus better explores the available free time and improves the stability of the system.The experimental results prove that the method used in the literature is more effective and available than the other methods.

摘要： 在实时控制系统中，由于并发和资源共享等诸多不确定的因素，导致周期任务每次被调度运行的时间有不确定性的变化，系统会变得不稳定。为了保证实时控制系统有较高的性能和可预测性，减小抖动是至关重要的。通过引入截止期缩减因子，对实时系统中抖动敏感的任务确定一个新的相对截止期，能够更好地挖掘出可用的空闲时间，从而使得系统的稳定性提高。实验结果证明提出的方法比文献中用到的其他方法更加有效和可用。