Research On Priority-based Preemptive Task Scheduling Mechanism In CPS

As a new generation of intelligent systems,CPS because of its superior performance plays an important role in many areas of medical,transportation,military,etc.But the challenge also followed,due to CPS system high real-time,high reliability,heterogeneity and other important features for the relevant technology also has a very high demand.This paper focuses on the task scheduling problem in CPS system,and studies the Characteristics,framework system and real-time system task scheduling evaluation criteria of CPS system,summarizes some kinds of more effective evaluation methods.In view of the CPS system high real time capability,high resource utilization requirements and heterogeneity,the three major characteristics,respectively from the three aspects are studied.The main contents of dissertation are:This paper expounds the development situation,main characteristics and system architecture of the CPS system.Analyze the important breakthroughs in the combination of CPS and several important technologies,summed up several distributed real-time system task scheduling evaluation criteria in CPS.Aiming at the high real-time requirement of CPS system,a buffer-able time model and a guard time model are proposed.On this basis,a real-time task scheduling strategy based on buffering time is proposed,judgment is made when the task may need to be switched,leave a task with a lower priority but not a pause,and make a higher priority task a little wait.Finally,by way of example and simulation results show that the algorithm can avoid frequent switching task jitter and its adverse effects on system performance generated,improve the real-time performance of the system.Analyzes several existing CPS real-time system architecture,an improved real-time system architecture model is proposed.Then established a gradient weight model,a preemptive real-time task scheduling algorithm based on gradient weight.Finally,verify its performance by experiment,comparing with the performance of two classical algorithms,confirm that it can better improve the utilization of resources within the system.Considering the complexity of the CPS real-time systems,and the diversity of equipment,further to the task of the CPS system is divided into several layers,and the priority from the original single task priority extensions to the scheduling priority and task priority two aspects.Finally using different for different kinds of real-time tasks scheduling mechanism,through the simulation experiment and described in this paper a comprehensive control strategy.Based on packet loss rate to verify the performance of this algorithm,and make sure it's more suitable for the system task is responsible for the high degree of CPS in real-time systems.