A Novel Method for Prediction of Mobile Robot Maneuvering Spaces

As the operational uses of mobile robots continue to expand, it becomes useful to be able to predict the admissible maneuvering space to prevent the robot from executing unsafe maneuvers. A novel method is proposed to address this need by using force-moment diagrams to characterize the robot’s maneuvering space in terms of path curvature and curvature rate. Using the proposed superposition techniques, these diagrams can then be transformed in real-time to provide a representation of the permissible maneuvering space while allowing for changes in the robot’s loading and terrain conditions. Simulation results indicate that the technique can be applied to determine the appropriate maneuvering space for a given set of loading conditions, longitudinal acceleration, and tire-ground coefficient of friction. This may lead to potential expansion in the ability to integrate predictive vehicle dynamics into autonomous controllers for mobile robots and a corresponding potential to safely increase operating speeds

A Proposed Learner-Centered Mechatronics Engineering Instructional Program

This paper examines the need and requirements for a mechatronics degree program. The results of a survey of the few existing programs in this field are provided. Then, using a case study example for Virginia Tech, a proposed mechatronics curriculum based on a learner-centered paradigm is described. The curriculum combines existing courses in mechanical, electrical, and computer engineering with new, hands-on courses to provide students with a chance to practice and explore the subject matter in ways consistent with the demands of both industry and accreditation. This program, if implemented, could provide a university with a unique offering to attract top students by better preparing them for the types of problems they will encounter in the modern world

Integrated Flight and Propulsion Control for Novel Rotorcraft

Distributed Electric Propulsion (DEP) has increased the design space for aerospace vehicles, especially those categorized as eVTOL (Electric Vertical Take-Off and Landing). This new class of vehicles not only looks different from the typical airplane or helicopter, but functions differently as well. A robust understanding of how the vehicle is controlled in both nominal and off-nominal modes will frame the approach to certification for private and commercial VTOL aircraft. Embry-Riddle Aeronautical University’s Eagle Flight Research Center (EFRC) is researching how the various methods of DEP thrust control apply to larger eVTOL vehicle operation. Researchers will utilize a mixture of flight dynamic simulation and physical testing in collaboration with FAA experts in rotorcraft handling qualities certification. Outcomes of the research include the characterization of various DEP thrust and moment control methods and how this maps to certifiable vehicle-level attributes like handling qualities in nominal and degraded flight modes. A prototype will be built and tested showing the ability of a quad-rotor vehicle to continue flight after the loss of thrust by failure of one rotor. It is anticipated that a better understanding of the DEP units will help inform the process of certification for the emerging market of urban air mobility vehicles. The data obtained from testing will be utilized to define the possible performance parameters, which will aid in developing appropriate means of compliance for advanced fly-by-wire N-rotor eVTOL vehicles

Characterization of MCF mammary epithelial cells overexpressing the Arylhydrocarbon receptor (AhR)

<p>Abstract</p> <p>Background</p> <p>Recent reports indicate the existence of breast cancer cells expressing very high levels of the Arylhydrocarbon receptor (AhR), a ubiquitous intracellular receptor best known for mediating toxic action of dioxin and related pollutants. Positive correlation between the degree of AhR overexpression and states of increasing transformation of mammary epithelial cells appears to occur in the absence of any exogenous AhR ligands. These observations have raised many questions such as why and how AhR is overexpressed in breast cancer and its physiological roles in the progression to advanced carcinogenic transformation. To address those questions, we hypothesized that AhR overexpression occurs in cells experiencing deficiencies in normally required estrogen receptor (ER) signaling, and the basic role of AhR in such cases is to guide the affected cells to develop orchestrated cellular changes aimed at substituting the normal functions of ER. At the same time, the AhR serves as the mediator of the cell survival program in the absence of ER signaling.</p> <p>Methods</p> <p>We subjected two lines of Michigan Cancer Foundation (MCF) mammary epithelial cells to 3 different types ER interacting agents for a number of passages and followed the changes in the expression of AhR mRNA. The resulting sublines were analyzed for phenotypical changes and unique molecular characteristics.</p> <p>Results</p> <p>MCF10AT1 cells continuously exposed to 17-beta-estradiol (E2) developed sub-lines that show AhR overexpression with the characteristic phenotype of increased proliferation, and distinct resistance to apoptosis. When these chemically selected cell lines were treated with a specific AhR antagonist, 3-methoxy-4-nitroflavone (MNF), both of the above abnormal cellular characteristics disappeared, indicating the pivotal role of AhR in expressing those cellular phenotypes. The most prominent molecular characteristics of these AhR overexpressing MCF cells were found to be overexpression of ErbB2 and COX-2. Furthermore, we could demonstrate that suppression of AhR functions through anti-AhR siRNA or MNF causes the recovery of ERalpha functions.</p> <p>Conclusion</p> <p>One of the main causes for AhR overexpression in these MCF breast cancer cells appears to be the loss of ERalpha functions. This phenomenon is likely to be based on the mutually antagonistic relationship between ER and AhR.</p

A New Troodontid Theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America

Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species--Troodon formosus--presently known from substantial skeletal remains.Here we report a gracile new troodontid theropod--Talos sampsoni gen. et sp. nov.--from the Upper Cretaceous Kaiparowits Formation, Utah, USA, representing one of the most complete troodontid skeletons described from North America to date. Histological assessment of the holotype specimen indicates that the adult body size of Talos was notably smaller than that of the contemporary genus Troodon. Phylogenetic analysis recovers Talos as a member of a derived, latest Cretaceous subclade, minimally containing Troodon, Saurornithoides, and Zanabazar. MicroCT scans reveal extreme pathological remodeling on pedal phalanx II-1 of the holotype specimen likely resulting from physical trauma and subsequent infectious processes.Talos sampsoni adds to the singularity of the Kaiparowits Formation dinosaur fauna, which is represented by at least 10 previously unrecognized species including the recently named ceratopsids Utahceratops and Kosmoceratops, the hadrosaurine Gryposaurus monumentensis, the tyrannosaurid Teratophoneus, and the oviraptorosaurian Hagryphus. The presence of a distinct troodontid taxon in the Kaiparowits Formation supports the hypothesis that late Campanian dinosaurs of the Western Interior Basin exhibited restricted geographic ranges and suggests that the taxonomic diversity of Late Cretaceous troodontids from North America is currently underestimated. An apparent traumatic injury to the foot of Talos with evidence of subsequent healing sheds new light on the paleobiology of deinonychosaurians by bolstering functional interpretations of prey grappling and/or intraspecific combat for the second pedal digit, and supporting trackway evidence indicating a minimal role in weight bearing

The VictorTango Architecture for Autonomous Navigation in the DARPA Urban Challenge

To solve the autonomous urban driving problem presented by the 2007 DARPA urban challenge, team VictorTango developed a tri-level architecture with a deliberative-reactive-deliberative structure. The VictorTango architecture emphasizes a robust, reusable, and modular design, using hardware-independent virtual actuators and virtual sensors. Details of the urban challenge implementation are provided, highlighting the functionalities and interactions of different modules within the architecture. Situational examples from the urban challenge problem illustrate the performance of the architecture in real-world situations, and communications latencies with their effect on decision making are analyzed. Finally, recommendations for future refinement of the architecture are presented. The VictorTango architecture ultimately proved capable of completing the urban challenge problem. Furthermore, the modularity, hardware independence, and robustness of the architecture have enabled it to be applied to other platforms and other problems in the unmanned systems field

Odin: Team VictorTango\u27s entry in the DARPA Urban Challenge

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 toanalyze 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\u27s work was successful completion of the Urban Challenge and a third-place finish. © 2008 Wiley Periodicals, Inc

Development of the Ground Unmanned Support Surrogate

The Ground Unmanned Support Surrogate (GUSS) was developed by NSWC Dahlgren, Virginia Tech, and TORC Technologies as an autonomous squad support ground vehicle for the Marine Corps Warfighting Lab (MCWL). GUSS is intended to test the ability of autonomous ground vehicle technology to provide Marine rifle squads with an organic transport, resupply, casualty evacuation, and RISTA capability. The primary operational mode is a follow-me capability in which the GUSS navigates autonomously across unstructured terrain to keep pace with an operator carrying a handheld operator control unit. Other modes of operation include resupply missions using a map-based planner, point-and-click local navigation, RISTA missions using teleoperation, as well as an optional manned operation capability. To test the GUSS capability, four vehicles participated in the MCWL Limited Objective Experiment Four (LOE-4) in conjunction with RIMPAC 2010 at the Marine Corps Training Area Bellows in Hawaii. Marine operators were trained to operate the system and the vehicles were turned over to a Marine platoon for four days of simulated field operations. An overview of the development and capabilities of the GUSS system will be provided followed by a discussion of the operational experiences, lessons learned, and future development plans

VictorTango Architecture for Autonomous Navigation in the DARPA Urban Challenge

To solve the autonomous urban driving problem presented by the 2007 Defense Advanced Research Project Agency Urban Challenge, team VictorTango developed a tri-level architecture with a deliberative-reactive-deliberative structure. The VictorTango architecture emphasizes a robust, reusable, and modular design, using hardware independent virtual actuators and virtual sensors. Details of the Urban Challenge implementation are provided, highlighting the functionalities and interactions of different modules within the architecture. Situational examples from the Urban Challenge problem illustrate the performance of the architecture in real-world situations, and communications latencies with their effect on decision making are analyzed. Finally, recommendations for future refinement of the architecture are presented. The VictorTango architecture ultimately proved capable of completing the Urban Challenge problem. Furthermore, the modularity, hardware independence, and robustness of the architecture have enabled it to be applied to other platforms and other problems in the Unmanned Systems field

A Blueprint for a Fixed-wing Autopilot on an Android Smartphone

The growing set of potential applications for UAVs is driving research and development of more intelligent systems to prove feasibility of future integration into national airspace. An autonomous UAV architecture built upon a COTS Android smartphone is proposed as a platform for widespread development. A brief analysis is conducted on the feasibility of an open-source, inexpensive, user-friendly autonomous system, built upon the capabilities of a contemporary smartphone. An examination of flight control, position estimation, attitude determination, and long-range data connection through a Samsung Galaxy Nexus determines that this type of system may be developed by building on the concepts used in the existing Paparazzi autopilot software