Research And Implementation Of Supporting Hazard Analysis And Capturing Safety Requirements Tool

As safety critical system become more tightly integrated and complex,system failures tend to focus on unsafe interactions between system components,and traditional safety analysis methods based on failure-accident model such that Fault Tree Analysis(FTA)and Failure Modes and Effects Analysis(FMEA)cannot effectively find interactive errors.Engineering experience shows that the SystemTheoretic Process Analysis(STPA)method can clearly solve this problem.However,at present,STPA method lacks the support of automatic tool.This thesis designs an automatic tool for supporting hazard analysis and capturing safety requirements.In order to support the safety analysis and engineering application,we add the function of verifying safety constraints for the automatic tool.The main research work of this thesis includes the following contents:Firstly,aiming at the shortcomings of existing tools,we make an in-depth research of STPA basic element models,generate unsafe control actions and automatic verification.To solve the problem that existing tools can only assist the simple editing function of STPA method for safety analysis,we support all of the steps and processes of STPA method,and add the functions of generating unsafe control actions and verification automatically.Secondly,we solve some specific technical difficulties in the implementation of tool,including how to build STPA basic element models and construct the constraint relationships of all the models,design the data structure and automatic generation algorithm of unsafe control actions,and describe the properties of model verification.Our tool implements the model design function of control structure diagram,automatic generation function of unsafe control actions and the extended function of safety properties verification.All of these functions can greatly reduce the repetitive work for safety analysts and the probability of human errors.Finally,we take safety analysis for Flight Guidance System as an example.Showing how to use our tool for safety analysis and give the analysis results.By comparing with traditional safety analysis methods,we can find the superiority of STPA method and the effectiveness of our tool.