一种面向数控系统的动态反馈调度模型

Dynamic Feedback-based Scheduling Model for CNC System

由于数控系统的动态特性,其运行过程中可能会发生处理器过载现象.开环的调度算法无法在处理器过载时仍然保持系统的稳定,从而对加工精度造成影响.为了提高数控系统的稳定性,本文针对数控系统的混合任务集提出一个闭环的反馈调度模型.并通过实验对模型的有效性进行了验证.实验结果表明,该调度模型能够提高数控系统的稳定性.

Because there is some sporadic tasks in the CNC system and the CNC system is sensitive to data,the CPU may overload aperiodic.In the case,some real-time task would break their deadline,and decrease the quality of machining.For increasing the steadiness of CNC system,we advance a dynamical scheduling model that is close loop.The model is PES-ACNR（Priority-based Elastic Scheduling-Admission control of Non-Real-time tasks）.It aims at the mixed tasks set.PES-ACNR can adjust the period of soft real-time task,according to the CPU utilization and the lost rate.And it can ensure the CPU utilization below the reference value.For decreasing the mount of disturbance to hard real-time tasks,we introduce a strategy of task admission.While the lost rate exceed during several sampling periods,the strategy would forbid some non-real-time tasks.We elaborate the architecture and algorithms of the PES-ACNR,and implement the model in the RTAI.At last,some experiments illustrate the validity of the scheme.It can improve the steadiness and the ability of adapting of the CNC system.