Auto-Landing System for Fixed-Wing Unmanned Aerial Vehicle

Unmanned aerial vehicle systems, or any kind or autonomous system, are relevant to many applications today. However, they are complex and sophisticated systems that require a deep understanding of multiple technologies. In addition, the mathematical rigor, computer modelling, and programming applications involved make t¬his a challenging field of study. This thesis explores the possibility of achieving the automated landing of a fixed-wing unmanned aerial vehicle. Auto-landing systems can resolve the challenges for the novice user and make aerial vehicle platforms accessible and dependable. A wide spectrum of applications such as agriculture, aerial photography, and security, to name a few, can utilize this technology. This thesis catalogs, describes, and analyzes the research into existing solutions, attainable technologies, and the process used to develop and validate a control algorithm that can land an airplane safely

Online Near Real-Time Online System Identification on Small Unmanned Aircraft Systems

An online near real-time system identification system is developed for generating locally linear models of Small Unmanned Air Systems. Automated control surface excitation inputs consisting of doublets, triplets, and frequency sweeps are implemented and used to assure consistency in the excitation and to eliminate errors introduced by user applied inputs. To provide reliable data for processing, a high frequency data acquisition unit is developed and implemented. In addition, a real-time vehicle monitoring system is used to provide a human-in-the-loop model update capability, with a goal of ensuring safety of the vehicle. Flight tests and modeling are demonstrated on a fixed-wing Small Unmanned Air System, with locally linear models generated during flight. Observer Kalman filter identification is used as the primary identification algorithm with adjustments made for real-time identification purposes. Identified models are both stored and sent to the ground control station for ground control operator for update verification. Results presented in the thesis show that the system provides a capability for generating accurate locally linear models that are suitable for real-time flight control design using model based control techniques and post-flight modal analysis

Architecture and Information Requirements to Assess and Predict Flight Safety Risks During Highly Autonomous Urban Flight Operations

As aviation adopts new and increasingly complex operational paradigms, vehicle types, and technologies to broaden airspace capability and efficiency, maintaining a safe system will require recognition and timely mitigation of new safety issues as they emerge and before significant consequences occur. A shift toward a more predictive risk mitigation capability becomes critical to meet this challenge. In-time safety assurance comprises monitoring, assessment, and mitigation functions that proactively reduce risk in complex operational environments where the interplay of hazards may not be known (and therefore not accounted for) during design. These functions can also help to understand and predict emergent effects caused by the increased use of automation or autonomous functions that may exhibit unexpected non-deterministic behaviors. The envisioned monitoring and assessment functions can look for precursors, anomalies, and trends (PATs) by applying model-based and data-driven methods. Outputs would then drive downstream mitigation(s) if needed to reduce risk. These mitigations may be accomplished using traditional design revision processes or via operational (and sometimes automated) mechanisms. The latter refers to the in-time aspect of the system concept. This report comprises architecture and information requirements and considerations toward enabling such a capability within the domain of low altitude highly autonomous urban flight operations. This domain may span, for example, public-use surveillance missions flown by small unmanned aircraft (e.g., infrastructure inspection, facility management, emergency response, law enforcement, and/or security) to transportation missions flown by larger aircraft that may carry passengers or deliver products. Caveat: Any stated requirements in this report should be considered initial requirements that are intended to drive research and development (R&D). These initial requirements are likely to evolve based on R&D findings, refinement of operational concepts, industry advances, and new industry or regulatory policies or standards related to safety assurance

Acoustic Wind Tunnel Measurements of a Quadcopter in Hover and Forward Flight Conditions

An experimental testing campaign was conducted in the NASA Langley Low Speed Aeroacoustic Wind Tunnel (LSAWT) in order to better understand the acoustic characteristics of a representative quadcopter system in both hover and forward flight conditions. Aerodynamic performance measurements were acquired using a multi-axis load cell to trim the vehicle to desired thrust/lift conditions. Hover acoustic measurements provide evidence of prominent rotor-airframe interaction noise that manifests in the form of high-amplitude harmonics of the fundamental rotor blade passage frequency. Forward flight acoustic measurements of simultaneous rotor operations indicate the presence of strong forward-aft rotor wake interactions that yield increased broadband noise levels relative to cases of individual rotor operation. These results indicate the potential need for modeling complex noise generation mechanisms associated with multirotor and rotor-airframe interactions for vehicles of this class