Runtime Assurance for Autonomous Aerospace Systems

This paper presents a runtime assurance (RTA) framework for an unmanned aerospace application. RTA systems hold the promise of protecting feedback systems that contain advanced or experimental elements that cannot be completely tested at design time to their required levels of assurance. This inability of fully trusting such advanced systems is due to their inherent complexity and that current analysis, verification, and validation protocols cannot address such complexity. The necessary structure of RTA frameworks for multilevel interacting feedback systems is investigated. A challenge problem is constructed for a fleet of unmanned aircraft systems performing complex missions. The complete study involves integrating RTA systems for the inner-loop control, outer-loop guidance, vehicle flight management, and runtime mission planning elements. The RTA interactions between these feedback levels are explored in this effort. General required RTA checks are presented and the critical reversionary switching conditions defined. More detailed system design is presented for the outer-loop guidance feedback level.