Recent advances in computing enable Unmanned Aircraft Systems (UAS) to conduct high quality missions with the implicit promise of lower cost and effort than manned aircraft. However, a lack of methods, architectures, and tools to enable verification, validation, and certification of UAS flight control systems is a major technological barrier to widespread adoption of UAS in civil aviation and NASA research. Our innovation, Safety Assurance through Flight envelope Estimation in Real-time (SAFER), establishes trust through real-time estimation of safe and robust flight envelope boundaries and providing feedback and command limiting to keep the UAS within those boundaries. We propose to estimate these boundaries with an independent hardware module, requiring only effector commands as input, and enabling any UAS to meet verification, validation, and certification requirements. Internally, our system will consist of an Inertial Measurement Unit, Global Navigation Satellite System receiver, and a processor. A cascaded set of Extended Kalman Filters will estimate inertial and synthetic air data states from IMU and GNSS data. Real-time identification and estimation methods will use these states to identify and estimate highly accurate and globally valid aircraft models, which will be used to estimate flight envelope boundaries and flight control system stability margins. Stability margins will be projected to the flight envelope boundaries to identify the envelope with adequate stability margins. Effector command limiting and feedback will be provided to keep the UAS within the stable and robust flight envelope boundaries. Phase I will establish feasibility through developing a prototype system and testing in simulation and flight test. Phase II is expected to mature the technologies and integrate low risk components. With an independent estimator of states, stability, and flight envelope boundaries, many potential applications exist within civil aviation and NASA research. Potential NASA Applications (Limit 1500 characters, approximately 150 words) Enables any UAS to meet verification, validation, and certification requirements, dramatically lowering the time and cost of flight research and NASA Earth Science remote sensing. Independent estimation of state data for rapid control system development and strap-down flight data recording. Estimation of flight envelope boundaries for increased situational awareness and safety. Independent estimation of flight envelope enables advanced and autonomous flight termination systems. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words) Enables any UAS to meet verification, validation, and certification requirements, including current UAS and non-deterministic systems. Independent estimation and recording of state data, stability, and flight envelope for post-incident analysis and as a monitor for UAS insurance companies. Estimation of incipient stall and flutter for increased situational awareness and safety.
