Extending safety control structures: a knowledge graph for STAMP

Extending safety control structures: a knowledge graph for STAMP 04-Sep-23 ESREL 2023 Francesco Simone 1 Antonio J. Nakhal 1 Antonello Alvino 2 Silvia M. Ansaldi 2 Patrizia Agnello 2 Maria F. Milazzo 3 Giulio Di Gravio 1 Riccardo Patriarca 1 1. University of Rome “La Sapienza” 2. INAIL 3. University of Messina Socio-technical systems: Collection of technical and social aspects of a system or organization. STSs reflect the goal of integrating the social requirements of people’s work with the technical requirements needed to keep proper system’s performance Context 04/09/2023 2 ESREL 2023 INTERACTIONS → COMPLEXITY → SAFETY?! •Combines systems theory and control theory to have a new perspective on systems’ safety •Systems perspective incorporates effects on and mutual dependencies amongst system elements •Control theory views systems as collections of interrelated components to be kept in dynamic equilibrium by feedback loops and controls System Theoretic Accident Model and Processes (STAMP) 04/09/2023 3 ESREL 2023 04/09/2023 4 Safety control structures SCSs (Leveson, 2011) are hierarchical models made by : •Controlled processes •Controllers •Control actions •Feedbacks •Inputs and outputs •External disturbances (maybe) ESREL 2023 04/09/2023 5 Safety control structure (example 1) ESREL 2023 04/09/2023 6 Safety control structure (example 2) ESREL 2023 •Which is the system element who sends the higher number of feedbacks? •Which is the shortest sequence of elements to be informed to send a control action from a controller (e.g., the top one) to the lower-level controlled process? •Which is the element that is contained in these sequences more often? Three questions for the audience 04/09/2023 7 ESREL 2023 •Which is the system element who sends the higher number of feedbacks? •Which is the shortest sequence of elements to be informed to send a control action from a controller (e.g., the top one) to the lower-level controlled process? •Which is the element that is contained in these sequences more often? Three questions for the audience 04/09/2023 8 ESREL 2023 •Which is the system element who sends the higher number of feedbacks? •Which is the shortest sequence of elements to be informed to send a control action from a controller (e.g., the top one) to the lower-level controlled process? •Which is the element that is contained in these sequences more often? Three questions for the audience 04/09/2023 9 ESREL 2023 04/09/2023 16 Exemplary use case (LNG storage) ESREL 2023 •Nodes i outdegree filtered on relationships defined_by connected to nodes with label FEEDBACK •Shortest path between a node with label CONTROLLER (A) to a node with label CONTROLLED PROCESS (B) •Compute k nodes betweenness Three answers for the audience 04/09/2023 17 ESREL 2023 04/09/2023 18 ESREL 2023 •Knowledge graph analyses driven by STAMP principles helps in identifying and understanding systems interactions and potential hazards •The STAMP ontology promotes shared understanding and consistency between knowledge in safety domain •When is the information graph complete? Need to validate •Need to specify attributes or sub-classes (standard ontologies in a “multi-layer” graph) to further specify and treat information in the graph. Conclusions Extending safety control structures: a knowledge graph for STAMP 04-Sep-23 ESREL 2023 Contact me: [email protected] RE-SET project website: https://sites.google.com/uniroma1.it/bric-reset/home