Bridge inspections are an important procedure for maintaining the infrastructure vital to our economy and well-being. The current methodology of utilizing specialized equipment such as snooper trucks and scaffolding to support manned-inspections poses a significant financial cost, disrupts traffic, and is dangerous to the inspectors and public. The advent of unmanned aerial systems (UAS), more commonly called drones, presents a practical solution that promises reduced cost, enhanced safety, and is significantly less intrusive than previous methodologies. Current limitations in the implementation of UAS include the reliance on a skilled operator and/or the requirement for a UAS to operate in a cluttered, GPS-denied environment. A solution to these challenges is presented in this paper by utilizing commercial off-the-shelf (COTS) hardware including laser rangefinders, optical flow sensors, and live video telemetry. Included in the system is the obstacle avoidance equipped drone and a ground station intended to be manned by a pilot and bridge inspector. The proposed custom-fabricated UAS was implemented during eight inspections of Florida Department of Transportation (FDOT) bridges. The UAS was able to navigate under GPS-denied and obstacle-laden bridge decks with position-hold performance comparable to, if not better than, a COTS unit in an unobstructed environment. The position hold capability maintained an altitude of ±12.8 cm with a horizontal hold of ±435 cm. Details of the hardware, algorithm development, and suggestions for future research are discussed in this paper.
A novel biomimetic morphing micro aerial vehicle was designed using macro fiber composites (MFCs) as control actuators. The vehicle features variable-sweep, multi-curved wings, and a tail, both of which were embedded with MFC bimorphs. The wing design has a span of 1.1 m unswept (wings fully extended) and 0.65 m swept, resembling falcons (Falco Peregrinus). A design study was conducted on the outboard wing’s MFC and carbon fiber substrate orientation to enhance the roll authority of the wings when fully extended. Finite element modeling, wind tunnel testing, and flight testing were conducted to model and optimize the design to obtain linear aerodynamic control with given MFC deflections. In addition, this research explores several configurations to increase roll authority of MFCs using segmented and overlapped sections resembling avian feathers. An overlapped wing configuration was discovered to have the potential to increase roll authority at the expense of adverse yaw. Flight testing proved that MFC-actuated, continuous outboard wings provide sufficient roll authority and handling quality without added compensation for the non-linear behavior of MFCs. This research showed that MFCs can be incorporated into a morphing wing design for manual flight and autonomous flight through feedback from inertial sensors onboard the vehicle.
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