The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with ...The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.展开更多
To solve the problem of risk identification and quantitative assessment for human-computer interaction(HCI)in complex avionics systems,an HCI safety analysis framework based on system-theoretical process analysis(STPA...To solve the problem of risk identification and quantitative assessment for human-computer interaction(HCI)in complex avionics systems,an HCI safety analysis framework based on system-theoretical process analysis(STPA)and cognitive reliability and error analysis method(CREAM)is proposed.STPACREAM can identify unsafe control actions and find the causal path during the interaction of avionics systems and pilot with the help of formal verification tools automatically.The common performance conditions(CPC)of avionics systems in the aviation environment is established and a quantitative analysis of human failure is carried out.Taking the head-up display(HUD)system interaction process as an example,a case analysis is carried out,the layered safety control structure and formal model of the HUD interaction process are established.For the interactive behavior“Pilots approaching with HUD”,four unsafe control actions and35 causal scenarios are identified and the impact of common performance conditions at different levels on the pilot decision model are analyzed.The results show that HUD's HCI level gradually improves as the scores of CPC increase,and the quality of crew member cooperation and time sufficiency of the task is the key to its HCI.Through case analysis,it is shown that STPACREAM can quantitatively assess the hazards in HCI and identify the key factors that impact safety.展开更多
Cyber-physical systems(CPSs)are becoming increasingly complex,integrating physical entities with diverse computing and communication resources,multiple processors,networks,and devices.One example is the Unmanned Aircr...Cyber-physical systems(CPSs)are becoming increasingly complex,integrating physical entities with diverse computing and communication resources,multiple processors,networks,and devices.One example is the Unmanned Aircraft Systems(UAS)Traffic Management(UTM)system,where interactions among components can lead to UAS collisions and harm to people and property.System Theoretic Process Analysis(STPA)is a systems theory-based technique for conducting early-stage safety analyses of complex systems.The Model the Control Structure step in STPA involves identifying each controller component,its process models,and its control actions.However,conventional STPA process models use only variables and states,which may be insufficient for systems involving entities that transition through multiple state flows.This study introduces a novel extension by integrating Finite State Machine(FSM)modeling into the Model the Control Structure step.The FSM-based approach captures detailed behaviors of entities requiring control by explicitly modeling their states and transitions in an iterative process.This extended STPA was applied to the UTM to control the delivery of UAV packages.The results demonstrate that the FSM extension enhances identifying control actions,feedback loops,process model variables,and unsafe control actions.The study concludes that the extended STPA provides a systematic approach for analyzing CPSs with entities that undergo complex state transitions,contributing to improved systematization and consistency of safety analyses.展开更多
文摘The wheel brake system safety is a complex problem which refers to its technical state, operating environment, human factors, etc., in aircraft landing taxiing process. Usually, professors consider system safety with traditional probability techniques based on the linear chain of events. However, it could not comprehensively analyze system safety problems, especially in operating environment, interaction of subsystems, and human factors. Thus,we consider system safety as a control problem based on the system-theoretic accident model, the processes(STAMP) model and the system theoretic process analysis(STPA) technique to compensate the deficiency of traditional techniques. Meanwhile,system safety simulation is considered as system control simulation, and Monte Carlo methods are used which consider the range of uncertain parameters and operation deviation to quantitatively study system safety influence factors in control simulation. Firstly,we construct the STAMP model and STPA feedback control loop of the wheel brake system based on the system functional requirement. Then four unsafe control actions are identified, and causes of them are analyzed. Finally, we construct the Monte Carlo simulation model to analyze different scenarios under disturbance. The results provide a basis for choosing corresponding process model variables in constructing the context table and show that appropriate brake strategies could prevent hazards in aircraft landing taxiing.
基金supported by the National Key Research and Development Program of China(2021YFB1600601)the Joint Funds of the National Natural Science Foundation of China and the Civil Aviation Administration of China(U1933106)+2 种基金the Scientific Research Project of Tianjin Educational Committee(2019KJ134)the Natural Science Foundation of TianjinIntelligent Civil Aviation Program(21JCQNJ C00900)。
文摘To solve the problem of risk identification and quantitative assessment for human-computer interaction(HCI)in complex avionics systems,an HCI safety analysis framework based on system-theoretical process analysis(STPA)and cognitive reliability and error analysis method(CREAM)is proposed.STPACREAM can identify unsafe control actions and find the causal path during the interaction of avionics systems and pilot with the help of formal verification tools automatically.The common performance conditions(CPC)of avionics systems in the aviation environment is established and a quantitative analysis of human failure is carried out.Taking the head-up display(HUD)system interaction process as an example,a case analysis is carried out,the layered safety control structure and formal model of the HUD interaction process are established.For the interactive behavior“Pilots approaching with HUD”,four unsafe control actions and35 causal scenarios are identified and the impact of common performance conditions at different levels on the pilot decision model are analyzed.The results show that HUD's HCI level gradually improves as the scores of CPC increase,and the quality of crew member cooperation and time sufficiency of the task is the key to its HCI.Through case analysis,it is shown that STPACREAM can quantitatively assess the hazards in HCI and identify the key factors that impact safety.
基金supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)[grant number309620/2021-O]Fundaçao de AmparoàPesquisa do Estado de Sao Paulo(FAPESP)[grant number 2022/01051-7]CAPES PRINT[grant number 88881.310602/2018-01].
文摘Cyber-physical systems(CPSs)are becoming increasingly complex,integrating physical entities with diverse computing and communication resources,multiple processors,networks,and devices.One example is the Unmanned Aircraft Systems(UAS)Traffic Management(UTM)system,where interactions among components can lead to UAS collisions and harm to people and property.System Theoretic Process Analysis(STPA)is a systems theory-based technique for conducting early-stage safety analyses of complex systems.The Model the Control Structure step in STPA involves identifying each controller component,its process models,and its control actions.However,conventional STPA process models use only variables and states,which may be insufficient for systems involving entities that transition through multiple state flows.This study introduces a novel extension by integrating Finite State Machine(FSM)modeling into the Model the Control Structure step.The FSM-based approach captures detailed behaviors of entities requiring control by explicitly modeling their states and transitions in an iterative process.This extended STPA was applied to the UTM to control the delivery of UAV packages.The results demonstrate that the FSM extension enhances identifying control actions,feedback loops,process model variables,and unsafe control actions.The study concludes that the extended STPA provides a systematic approach for analyzing CPSs with entities that undergo complex state transitions,contributing to improved systematization and consistency of safety analyses.
