Research On Time-triggered Ethernet Real-time Task Scheduling Method Based On Constraint Programming

Security critical electronic system puts forward strict requirements for network real-time performance,data throughput performance and system compatibility.Standard Ethernet has the characteristics of wide application,high bandwidth and low cost.Time-Triggered Ethernet adds time-triggered messages on the basis of the network protocol,which greatly improves the real-time performance,security performance and stability of the system,and fully meets the business requirements of Avionics Full Duplex Switched Ethernet.However,with the increase of network scale and message density,how to schedule and synthesize network real-time tasks quickly and reasonably under the premise of ensuring the stability and security of electronic system has become a research hotspot and an important challenge of aerospace application-oriented TimeTriggered Ethernet technology.This paper focuses on the Time-Triggered Ethernet real-time task scheduling technology and its optimization under the fault-tolerant mechanism.The specific contents are as follows:(1)Starting from the frame structure,synchronization mechanism and scheduling mechanism of Time-Triggered Ethernet,this paper deeply studies the operation mechanism of Time-Triggered Ethernet.On this basis,a real-time task scheduling model of Time-Triggered Ethernet under multiple constraints is established.(2)The constraint programming technology is applied to the scheduling synthesis of real-time tasks of Time-Triggered Ethernet.Combined with All Different global constraints,a constraint programming scheduling synthesis method based on data link is proposed.In addition,the hop delay is used as a breakthrough to improve the scheduling synthesis method,a constraint programming scheduling synthesis method based on message is further proposed.In order to build an extensible experimental platform,XML is used as the representation of the network model,and IBM ILOG CP component is used as the solution tool to build a scheduling synthesis system and design multiple groups of simulation experiments to fully verify the solution performance of these two scheduling synthesis methods from multiple dimensions.The experimental results show that the message based scheduling synthesis method has lower topological sensitivity and higher scheduling synthesis efficiency.(3)This paper proposes the concept of time-triggered message fault,optimizes the network performance for maximizing the fault tolerance margin,and proposes a comprehensive scheduling optimization method based on the incremental basic scheduling unit,provides the corresponding time-triggered Ethernet fault tolerance scheme,and improves the stability and security of the integrated electronic system.The scheduling simulation system is designed on the OMNe T + + network simulation platform.The fault-tolerant performance of time-triggered messages and the real-time performance of non-real-time messages are simulated and evaluated.The research results show that after the fault-tolerant optimization of real-time task scheduling completion time-triggered message fault,the network system can significantly improve the fault-tolerant performance of time-triggered message fault at the cost of slightly reducing the real-time performance of non-real-time messages,and effectively guarantee the stability and security of the safety critical electronic system.