Outline MERS CSAIL Fault Aware Systems and Model-based Programming Model-based diagnosis Multiple-fault Diagnosis based on Conflicts Mode estimation Issue 1: Handling Hidden Failures Requires Reasoning from a Model: STS-93 Engine temp sensor high LOX level low GN&C detects low thrust H2 level possibly low Problem: Liquid hydrogen leak Effect LH2 used to cool engine Engine runs hot Consumes more lox Image courtesy of nasaOutline • Fault Aware Systems and Model-based Programming • Model-based Diagnosis • Multiple-fault Diagnosis based on Conflicts • Mode Estimation Issue 1: Handling Hidden Failures Requires Reasoning from a Model: STS-93Symptoms: • Engine temp sensor high • LOX level low • GN&C detects low thrust • H2 level possibly low Problem: Liquid hydrogen leak Effect: • LH2 used to cool engine • Engine runs hot • Consumes more LOX Image courtesy of NASA