Research On Safety Critical System Flow Model Modeling And Simulation Methods

The end-to-end latency of verification data flows is particularly important in aerospace,automotive,and aviation,where there are strong real-time requirements.The variation of end-to-end latency is influenced by factors such as processing time,sensor and actuator sampling time,and scheduling algorithms.End-to-end latency is the time it takes to process new data values from the sensors and output them to the actuators.End-to-end flow analysis is the check whether the end-to-end data flow with a delay value greater than the sum of each delay of the flow elements.This verification is performed for both the lower(minimum)and upper(maximum)bounds of the wait time values.Safety?SysML is our proposed semi-formal modeling language for modeling safety-critical system requirements and supporting requirements safety verification.It includes Safety?SysML State Machine(S2MSM)and Safety?SysML Flow Model(S2MFM).This paper studies data flow modeling,latency analysis,and scheduling analysis methods.Based on UML and SysML,combined with AADL data flow modeling semantics,a safety-critical system-oriented data flow model modeling language Safety?SysML flow model is proposed.We developed and improved the modeling tool platform.The main contributions of this paper are as follows:1.This paper proposes a UML and SysML based modeling language Safety?SysML flow model.Using this modeling language,the system functions are modeled at a higher level and the end-to-end latency is verified,which can provide assistance in selecting the appropriate architecture during the development phase.2.We developed a modeling tool platform for Safety?SysML flow model that allows efficient graphical modeling,setting of attribute values,and validation of data flows of the system,which simplifies the modeling steps of the flow model.As part of the tool platform,the conversion function from data flow graphs to XML files was implemented.We also implemented the XML file to AADL model conversion adapter.This Xml2 Aadl adapter,which ensures the compatibility of Safety?SysML flow models and AADL models,allows modelers to use AADL-related tools for further latency analysis.3.The formal syntax and semantics of S2 MFM are constructed,and the mapping rules from S2 MFM to UML profile are defined.The property set of each modeling element is constructed to represent the additional information or binding relationship of the model element for end-to-end flow latency analysis or schedulability verification.4.Analyzed the flow model verification methods including: end-to-end flow latency calculation method,and the principle of schedulability verification,and proposes the use of Cheddar in the context of integrated modular avionics system(IMA)hierarchical scheduling for simulation and verification method.These principles prove the feasibility and correctness of S2 MFM modeling language to model and verify safety-critical system software.In order to demonstrate the completeness and correctness of S2 MFM,we use S2 MFM to model and verify four cases,including delay analysis and schedulability verification.