Now showing items 25-44 of 50

    • Flight Results of Autonomous Fixed-Wing UAV Transitions to and from Stationary Hover 

      Johnson, Eric N.; Turbe, Michael A.; Wu, Allen D.; Kannan, Suresh K.; Neidhoefer, James C. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2006-08)
      Fixed-wing unmanned aerial vehicles (UAVs) with the ability to hover have significant potential for applications in urban or other constrained environments where the combination of fast speed, endurance, and stable ...
    • Flight Test Validation of a Neural Network based Long Term Learning Adaptive Flight Controller 

      Chowdhary, Girish; Johnson, Eric N. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2009-08)
      The purpose of this paper is to present and analyze flight test results of a Long Term Learning Adaptive Flight Controller implemented on a rotorcraft and a fixed wing Unmanned Aerial Vehicle. The adaptive control ...
    • Flight-Test Results of Autonomous Airplane Transitions Between Steady-Level and Hovering Flight 

      Johnson, Eric N.; Wu, Allen D.; Neidhoefer, James C.; Kannan, Suresh K.; Turbe, Michael A. (Georgia Institute of Technology, 2008-03)
      Linear systems can be used to adequately model and control an aircraft in either ideal steady-level flight or in ideal hovering flight. However, constructing a single unified system capable of adequately modeling or ...
    • Georgia Tech Aerial Robotics Team: 2009 International Aerial Robotics Competition Entry 

      Chowdhary, Girish; Christmann, Hans Claus; Johnson, Eric N.; Salaün, Erwan; Sobers, D. Michael Jr. (Georgia Institute of Technology, 2009-07)
      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 ...
    • Guidance, Navigation, Control, and Operator Interfaces for Small Rapid Response Unmanned Helicopters 

      Christmann, Hans Claus; Christophersen, Henrik B.; Wu, Allen D.; Johnson, Eric N. (Georgia Institute of Technology, 2008-04)
      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 ...
    • Indoor Navigation for Unmanned Aerial Vehicles 

      Sobers, D. Michael Jr.; Chowdhary, Girish; Johnson, Eric N. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2009-08)
      The ability for vehicles to navigate unknown environments is critical for autonomous operation. Mapping of a vehicle's environment and self-localization within that environ- ment are especially difficult for an Unmanned ...
    • Integration of Adaptive Estimation and Adaptive Control Design for Uncertain Nonlinear Systems 

      Sattigeri, Ramachandra J.; Calise, Anthony J.; Kim, Byoung Soo (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2007-08)
      This paper presents a method to integrate adaptive estimation and adaptive control designs for a class of uncertain nonlinear systems having both parametric uncertainties and unmodeled dynamics. The method is based on ...
    • Limited Authority Adaptive Flight Control for Reusable Launch Vehicles 

      Johnson, Eric N.; Calise, Anthony J. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2003-11)
      In the application of adaptive flight control, significant issues arise due to limitations in the plant inputs, such as actuator displacement limits, actuator rate limits, linear input dynamics, and time delay. A method ...
    • An LMI-based Stability Analysis for Adaptive Controllers 

      Yang, Bong-Jun; Yucelen, Tansel; Calise, Anthony J.; Shin, Jong-Yeob (Georgia Institute of Technology, 2009-06)
      We develop a Linear Matrix Inequality (LMI) tool for analyzing the stability and performance of adaptive controllers that employ σ−modification. The formulation involves recasting the error dynamics composed of the tracking ...
    • Methods for Localization and Mapping Using Vision and Inertial Sensors 

      Wu, Allen D.; Johnson, Eric N. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2008-08)
      The problems of vision-based localization and mapping are currently highly active areas of research for aerial systems. With a wealth of information available in each image, vision sensors allow vehicles to gather data ...
    • Modeling Urban Environments for Communication-Aware UAV Swarm Path Planning 

      Christmann, Hans Claus; Johnson, Eric N. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2010-08)
      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. ...
    • Modeling, Control, and Flight Testing of a Small Ducted Fan Aircraft 

      Johnson, Eric N.; Turbe, Michael A. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2006-07)
      Small ducted fan autonomous vehicles have potential for several applications, especially for missions in urban environments. This paper discusses the use of dynamic inversion with neural network adaptation to provide an ...
    • Nested Saturation with Guaranteed Real Poles 

      Johnson, Eric N.; Kannan, Suresh K. (Georgia Institute of TechnologyIEEE, 2003-06)
      The global stabilization of asymptotically null-controllable linear systems with bounded controls has been studied extensively. An early contribution was by Teel [6] who proposed a set of nested saturators to globally ...
    • Neural Network Augmented Kalman Filtering in the Presence of Unknown System Inputs 

      Sattigeri, Ramachandra J.; Calise, Anthony J. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2006-08)
      We present an approach for augmenting a linear, time-varying Kalman filter with an adaptive neural network (NN) for the state estimation of systems with linear process models acted upon by unknown inputs. The application ...
    • Neural-Network Augmentation of Existing Linear Controllers 

      Sharma, Manu; Calise, Anthony J. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2005-01)
      A method to augment existing linear controllers with a multilayer neural network is presented. The neural network is adapted online to ensure desired closed-loop response in the face of parametric plant uncertainty; ...
    • Real-Time System Identification of a Small Multi-Engine Aircraft 

      DeBusk, Wesley M.; Chowdhary, Girish; Johnson, Eric N. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2009-08)
      In-flight identification of an aircraft's dynamic model can benefit adaptive control schemes by providing estimates of aerodynamic stability derivatives in real time. This information is useful when the dynamic model ...
    • Real-Time Vision-Based Relative Aircraft Navigation 

      Johnson, Eric N.; Calise, Anthony J.; Watanabe, Yoko; Ha, Jin-Cheol; Neidhoefer, James C. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2007-03)
      This paper describes two vision-based techniques for the navigation of an aircraft relative to an airborne target using only information from a single camera fixed to the aircraft. These techniques are motivated by ...
    • Small Adaptive Flight Control Systems for UAVs Using FPGA/DSP Technology 

      Christophersen, Henrik B.; Pickell, Wayne J.; Koller, Adrian A.; Kannan, Suresh K.; Johnson, Eric N. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2004-09)
      Future small UAVs will require enhanced capabilities like seeing and avoiding obstacles, tolerating unpredicted flight conditions, interfacing with payload sensors, tracking moving targets, and cooperating with other ...
    • System Integration and Operation of a Research Unmanned Aerial Vehicle 

      Johnson, Eric N.; Schrage, Daniel P. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2004-01)
      The use of flight simulation tools to reduce the schedule, risk, and required amount of flight testing for complex aerospace systems is a well-recognized benefit of these approaches. However, some special challenges arise ...
    • UAS Reference Scenarios for MANET Development 

      Christmann, Hans Claus; Johnson, Eric N. (Georgia Institute of TechnologyAmerican Institute of Aeronautics and Astronautics, Inc., 2008-08)
      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 ...