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Navigation, Guidance, Control and Dynamics Commons

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2008

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Articles 1 - 11 of 11

Full-Text Articles in Navigation, Guidance, Control and Dynamics

Flexible Twist For Pitch Control In A High Altitude Long Endurance Aircraft With Nonlinear Response, Vanessa L. Bond Dec 2008

Flexible Twist For Pitch Control In A High Altitude Long Endurance Aircraft With Nonlinear Response, Vanessa L. Bond

Theses and Dissertations

Information dominance is the key motivator for employing high-altitude long-endurance (HALE) aircraft to provide continuous coverage in the theaters of operation. A joined-wing configuration of such a craft gives the advantage of a platform for higher resolution sensors. Design challenges emerge with structural flexibility that arise from a long-endurance aircraft design. The goal was to demonstrate that scaling the nonlinear response of a full-scale finite element model of a high-altitude long-endurance (HALE) aircraft was possible if the model was aeroelastically and "nonlinearly" scaled. A straight-forward method of scaling the first three natural vibration frequencies and mode shapes, and the first …


Application Of Parent-Child Uav Tasking For Wildfire Detection And Response, Stephen T. Kubik Dec 2008

Application Of Parent-Child Uav Tasking For Wildfire Detection And Response, Stephen T. Kubik

Master's Theses

In recent years, unmanned aerial vehicles (UAVs) have become a dominant force in the aerospace industry. Recent technological developments have moved these aircraft from remote operation roles to more active response missions. Of particular interest is the possibility of applying UAVs toward solving complex problems in long-endurance missions. Under that belief, the feasibility of utilizing UAVs for wildfire detection and response was investigated in a partnership that included NASA’s Aeronautics Research Mission Directorate and Science Mission Directorate, and the United States Forest Service. Under NASA’s Intelligent Mission Management (IMM) project, research was conducted to develop a mission architecture that would …


Control And Sensor Development On A Four-Wheel Pyramidal Reaction Wheel Platform, Jeffery Jay Logan Nov 2008

Control And Sensor Development On A Four-Wheel Pyramidal Reaction Wheel Platform, Jeffery Jay Logan

Master's Theses

The Pyramidal Reaction Wheel Platform, or PRWP, is used to simulate three-axis controls in a torque free space-like environment. The primary purpose of the system will be to evaluate the effects of conjoining sensors to maximize pointing accuracy. Furthermore, the system will incorporate a star tracker in conjunction with a Simulated Star Field (SSF) to better estimate the PRWP orientation. For the sake of this document, however, the goal is to implement a gyroscope, wheel rate sensors, and a make-shift accelerometer—to the PRWP—and integrate a controls algorithm such that three-axis controls are achieved for the PRWP. Three sensors were either …


Raising The Dead, Nihad E. Daidzic Aug 2008

Raising The Dead, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.


Tightly Integrating Optical And Inertial Sensors For Navigation Using The Ukf, Sedat Ebcin Mar 2008

Tightly Integrating Optical And Inertial Sensors For Navigation Using The Ukf, Sedat Ebcin

Theses and Dissertations

The motivation of this research is to address the benefits of tightly integrating optical and inertial sensors where GNSS signals are not available. The research begins with describing the navigation problem. Then, error and measurement models are presented. Given a set of features, a feature detection and projection algorithm is developed which utilizes inertial measurements to predict vectors in the feature space between images. The unscented Kalman filter is applied to the navigation system using the inertial measurements and feature matches to estimate the navigation trajectory. Finally, the image-aided navigation algorithm is tested using a simulation and an experiment. As …


Development And Flight Of A Robust Optical-Inertial Navigation System Using Low-Cost Sensors, Michael B. Nielsen Mar 2008

Development And Flight Of A Robust Optical-Inertial Navigation System Using Low-Cost Sensors, Michael B. Nielsen

Theses and Dissertations

This research develops and tests a precision navigation algorithm fusing optical and inertial measurements of unknown objects at unknown locations. It provides an alternative to the Global Positioning System (GPS) as a precision navigation source, enabling passive and low-cost navigation in situations where GPS is denied/unavailable. This paper describes two new contributions. First, a rigorous study of the fundamental nature of optical/inertial navigation is accomplished by examining the observability grammian of the underlying measurement equations. This analysis yields a set of design principles guiding the development of optical/inertial navigation algorithms. The second contribution of this research is the development and …


Antennas For Portable Communications In The Uwb And Gps Spectra., Giuseppe Ruvio Jan 2008

Antennas For Portable Communications In The Uwb And Gps Spectra., Giuseppe Ruvio

Doctoral

The thesis describes a study of antennas for solutions in emerging systems. An account of the fundamental principles of these antennas is given together with an outline of the basic electromagnetic theory on which the designs are based. While the main focus is on antennas for Ultra Wideband (UWB) systems, some additional work was carried out on enhancing performance of circularly polarised antennas for satellite navigation systems. The study focussed on the design of highly efficient broadband antennas with particular requirements for size compactness, gain stability, phase-linearity, and the use of low-cost materials. These requirements are particularly important for UWB …


An Improved Robust Projection Identification Algorithm To Manned Maneuvering Units, Bin Xu Jan 2008

An Improved Robust Projection Identification Algorithm To Manned Maneuvering Units, Bin Xu

Bin Xu

空间载人机动装置(MMU )在进行救援过程中, 其动力学参数存在很大的不确定性。为解决这一辨识问题, 本文首先推导系统关于各动力学参数的线性化模型, 然后结合该线性模型的特点, 提出了一种用于估计动力学参数的改进鲁棒投影算法, 并在理论上分析了该算法的收敛性质, 数字仿真验证了方法的有效性。


Extensible Simulation Of Planets And Comets, Natalie Anne Wiser-Orozco Jan 2008

Extensible Simulation Of Planets And Comets, Natalie Anne Wiser-Orozco

Theses Digitization Project

The aim of this research was to create an extensible simulator that will not only calculate the trajectories of planets and comets using a numerical method, but be able to graphically simulate them. The significance of this project is its ability to be a useful tool to computer scientists, astronomers, and physicists by determining how an arbitrary set of celestial bodies interact with one another. It allows definition of bodies that belong to a system, and creates a graphical simulation of them based on their specific properties. Ideas are then easily conveyed not only to colleagues, but to the public …


Experimental Investigation Of Active Control Of Bluff Body Vortex Shedding, Ilteris Koc Jan 2008

Experimental Investigation Of Active Control Of Bluff Body Vortex Shedding, Ilteris Koc

Mechanical & Aerospace Engineering Theses & Dissertations

Mean and fluctuating forces acting on a body are strongly related to vortex shedding generated behind it. Therefore, it is possible to obtain substantial reductions of at least the unsteady forces if vortex shedding is controlled or its regularity is reduced. While conventional active flow control methods are mainly concerned with direct interaction with, and alteration of, the mean flow about a body, modern techniques involve altering existing flow instabilities using relatively small inputs to obtain large-scale changes of mean flows. Aerodynamic flow control may be intended to delay or suppress boundary layer separation through creation of a boundary layer …


Towards A Metric For The Assessment Of Safety Critical Control Systems, Oscar R. Gonzalez, Jorge R. Chavez-Fuentes, W. Steven Gray Jan 2008

Towards A Metric For The Assessment Of Safety Critical Control Systems, Oscar R. Gonzalez, Jorge R. Chavez-Fuentes, W. Steven Gray

Electrical & Computer Engineering Faculty Publications

There is a need for better integration of the fault tolerant and the control designs for safety critical systems such as aircraft. The dependability of current designs is assessed primarily with measures of the interconnection of fault tolerant components: the reliability function and the mean time to failure. These measures do not directly take into account the interaction of the fault tolerant components with the dynamics of the aircraft. In this paper, a first step to better integrate these designs is made. It is based on the observation that unstable systems are intrinsically unreliable and that a necessary condition for …