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ItemModeling Urban Environments for Communication-Aware UAV Swarm Path Planning(Georgia Institute of Technology, 2010-08) Christmann, Hans Claus ; Johnson, Eric N.The presented work introduces a graph based approach to model urban (or otherwise cluttered) environments for UAS utilization beyond line-of-sight as well as out of direct R/F range of the operator's control station. Making the assumption that some a priori data of the environment is available, the proposed method uses a classification of obstacles with respect to their impact on UAV motion and R/F communication and generates continuously updateable graphs usable to compute traverseable paths for UAVs while maintaining R/F communication. Using a simulated urban scenario this work shows that the proposed modeling method allows to find reachable loiter or hover areas for UAVs in order to establish a multi-hop R/F communication link between a primary UAV and its remote operator by utilizing an overlay of motion (Voronoi based) and R/F (visibility based) specific mapping methods.
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ItemGeorgia Tech Aerial Robotics Team: 2009 International Aerial Robotics Competition Entry(Georgia Institute of Technology, 2009-07) Chowdhary, Girish ; Christmann, Hans Claus ; Johnson, Eric N. ; Salaün, Erwan ; Sobers, D. Michael Jr.This paper examines the use of low-cost range and target identification sensors on a stable flying vehicle for suitability in solving the 5th Mission proposed for the 2009 International Aerial Robotics Competition. The ability for vehicles to navigate unknown environments is critical for autonomous operation. Mapping of a vehicle's environment and self-localization within that environment are especially difficult for an Unmanned Aerial Vehicle (UAV) due to the complexity of UAV attitude and motion dynamics. Using a stable vehicle platform and taking advantage of the geometric structure typical of most indoor environments reduces the complexity of the localization and mapping problem to the point that wall and obstacle location can be determined using low-cost range sensors. Target identification is accomplished remotely using an onboard video camera with a radio transmitter. Thus complex and time-consuming image processing routines are run on a more powerful computer, enabling further miniaturization of the flight vehicle.
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ItemUAS Reference Scenarios for MANET Development(Georgia Institute of Technology, 2008-08) Christmann, Hans Claus ; Johnson, Eric N.After autonomous flight for Unmanned Aerial Vehicles (UAVs) has been accomplished, research was stipulated to look into application related challenges in connection with Unmanned Aerial Systems (UAS). As one possible scenario, swarms of collaborating UAVs can be envisioned and allow for more complex missions and scenarios. One essential building block in simultaneously operating several UAVs is the UAS internal and external communication. Ground control station operators need to communicate guidance, navigation, and control (GNC) data, external beneficiaries of the UAS operation need to be provided with obtained sensor data and intelligence. All this requires sophisticated wireless communication networks and Mobile Ad-hoc Networks (MANETs) step into the picture. However, evaluating the performance of different MANETs in a UAS environment is non-trivial: relevant metrics and evaluation procedures have to be established for a simulation based performance prediction during the design phase of a MANET. Unfortunately, published results on MANET performance are not necessarily comparable across different papers, due to differences in the underlying assumptions. Some findings might not even be applicable to a UAS environment. This paper proposes a set of reference scenarios in order to allow for comparable and applicable results in MANET simulations. The presented scenarios mimic realistic UAS missions, both, on the operational side of the participating network nodes, as well as on the network traffic side. The reference scenarios capture the essence of current UAVs and UAS missions in a civil, research, or military context, hence providing the means to simulate different MANET protocols in a UAS setting.
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ItemGuidance, Navigation, Control, and Operator Interfaces for Small Rapid Response Unmanned Helicopters(Georgia Institute of Technology, 2008-04) Christmann, Hans Claus ; Christophersen, Henrik B. ; Wu, Allen D. ; Johnson, Eric N.This paper focuses on the development of small rapid response reconnaissance unmanned helicopters (1 to 3 kg, electric), for use by the military in urban areas and by civilian first responders, in terms of system architecture, automation (including navigation, flight control, and guidance), and operator interface designs. Design objectives include an effective user interface, a vehicle capable of smooth and precise motion control, an ability to display clear images to an operator, and a vehicle that is capable of safe and stable flight.
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ItemDesign and Implementation of a Self-configuring Ad-hoc Network for Unmanned Aerial Systems(Georgia Institute of Technology, 2007-10) Christmann, Hans Claus ; Johnson, Eric N.Unmanned aerial vehicles (UAVs), and unmanned aerial systems (UAS) as such in general, need wireless networks in order to communicate. UAS are very flexible and hence allow for a wide range of missions by means of utilizing different UAVs according to the mission requirements. Each of these missions also poses special needs and requirements on the communication network. Especially, mission scenarios calling for UAV swarms increase the complexity and call for specialized communication solutions. This work focuses on these specialties and needs and describes the selection process, adaptation and implementation of an ad-hoc routing protocol tailored to an UAV surrounding and a correspondingly adapted communication method.