Description: When an ISHM module identifies a single failure, an associated response procedure, developed and validated in advance, can be selected for execution to verify the diagnosis, safe the system, and perform recovery. However, the ISHM system might return a diagnosis that indicates multiple failures. Or, it might return an ambiguity group that identifies more than one candidate failure. When multiple failures or ambiguous diagnoses occur, it seems attractive to exploit procedures that were developed in advance to handle each of the individual failures. However, simply combining procedures in just any order might not work due to interactions among the procedure goals and effects. We propose to develop the Multiple Failure Response Procedure System, which will automatically generate and present procedures for responding to multiple failures and ambiguity groups. During this project, we will iteratively design, implement, and evaluate algorithms for generating multi-failure procedures from procedures developed for responding to single failures. Our approach is based on the belief that it is usually easier to develop procedures and plans from existing procedures that serve as large building blocks, compared to search-intensive methods that construct procedures from primitive steps. To identify and resolve procedure interactions, we will translate procedure specifications into planning domain actions, apply automated planning systems to generate a valid plan, and then translate the plan back into a combined procedure. We will design the procedure generation algorithm and user interface, develop a software prototype, and apply it to several scenarios to demonstrate our approach.

Benefits: The technology resulting from this research will generate multi-failure response procedures from single-failure procedures in real-time when multiple failures occur or when ambiguous diagnoses are returned by automated diagnostic systems. This capability will extend the range of adverse situations for which procedures can be provided to support crew members and ground-based flight controllers. These multi-failure procedures can be used to respond to failures in air vehicles, space vehicles (manned and unmanned), and space habitats.

This technology can be used to enhance the range of adverse situations that can be supported by response procedures in other types of critical systems such as nuclear power plants and chemical plants, power distribution systems, and emergency response systems.