The DARPA Urban Challenge required robotic vehicles to travel more than 90 km through an urban environment without human intervention and included situations such as stop intersections, traffic merges, parking, and roadblocks. Team VictorTango separated the problem into three parts: base vehicle, perception, and planning. A Ford Escape outfitted with a custom drive-by-wire system and computers formed the basis for Odin. Perception used laser scanners, global positioning system, and a priori knowledge to identify obstacles, cars, and roads. Planning relied on a hybrid deliberative/reactive architecture to Robotics-2008 analyze the situation, select the appropriate behavior, and plan a safe path. All vehicle modules communicated using the JAUS (Joint Architecture for Unmanned Systems) standard. The performance of these components in the Urban Challenge is discussed and successes noted. The result of VictorTango's work was successful completion of the Urban Challenge and a third-place finish. C 2008 Wiley Periodicals, Inc.
Remote-controlled (RC) unmanned aerial vehicles (UAVs) have been used to study the movement of agricultural threat agents (e.g., plant and animal pathogens, invasive weeds, and exotic insects) above crop fields, but these RC UAVs are operated entirely by a ground-based pilot and often demonstrate large fluctuations in sampling height, sampling pattern, and sampling speed. In this paper, we describe the development and application of an autonomous UAV for precise aerobiological sampling tens to hundreds of meters above agricultural fields. We equipped a Senior Telemaster UAV with four aerobiological sampling devices and a MicroPilot-based autonomous system, and we conducted 25 sampling flights for potential agricultural threat agents at Virginia Tech's Kentland Farm.To determine the most appropriate sampling path for aerobiological sampling above crop fields with an autonomous UAV, we explored five different sampling patterns, including multiple global positioning system (GPS) waypoints plotted over a variety of spatial scales. An orbital sampling pattern around a single GPS waypoint exhibited high positional accuracy and produced altitude standard deviations ranging from 1.6 to 2.8 m.
The HECS wing, developed by NASA Langley Research Center, features a nonplanar, hyperelliptically swept leading and trailing edge as well as spanwise camber. In this paper, we propose a single-degree-of-freedom mechanism to provide a means for the wing to continuously morph from a planar to a nonplanar configuration. The mechanism, which is something like a scissor linkage, uses a repeating quaternary-binary link configuration to translate the motion from one wing segment to the next. The mechanism is synthesized such that, with one input to the first segment in the chain, the other wing segments move into their desired positions. To predict the aerodynamic loads associated with this morphing dihedral change, linear theory is applied to the HECS wing configuration at distinct morphed positions. For the structural study, a finite element representation of the mechanism is developed, and a linear static analysis at different morphed positions is performed. Using the predicted aerodynamic loads, the structural analysis investigates different materials and cross sections of the mechanism members to determine a need for redesign due to failure from buckling and bending stress. A design is finalized which, compared to the design of the original model, lightens the structure as well as increases its strength. These results are beneficial for the next phase of model development of the mechanism. This work shows that a relatively simple kinematic mechanism can produce the desired range of motion for a variable dihedral HECS wing. It also provides insight into the aerodynamic effects of the nonplanar wing configuration with an analysis of the structural integrity of the mechanism under loading. Nomenclature
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