Dynamic Feedback-based Scheduling Model for CNC System
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.