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Full-Text Articles in Engineering
Final Development, Testing, And Flight Preparation Of The Rigidizable Get-Away-Special Experiment (Rigex), Zachary R. Miller
Final Development, Testing, And Flight Preparation Of The Rigidizable Get-Away-Special Experiment (Rigex), Zachary R. Miller
Theses and Dissertations
The purpose of this research is to support the final development of the Rigidizable Inflatable Get-Away-Special Experiment (RIGEX). The RIGEX program is an experimental initial step in developing large-scale rigidizable inflatable structures, which can be utilized in space applications. The primary intent of RIGEX is to verify and validate ground testing of inflation and rigidization methods for inflatable space structures against a zero-gravity space environment. This is performed by designing a Canister for All Payload Ejections (CAPE) experiment to collect data on space rigidized structures for validation of ground testing methods. The results presented in this thesis provide documentation needed …
Development And Testing Of An Inflatable, Rigidizable Space Structure Experiment, Sarah K. Helms
Development And Testing Of An Inflatable, Rigidizable Space Structure Experiment, Sarah K. Helms
Theses and Dissertations
Many recent space technology concepts require large space structures such as solar arrays and large aperture antennas; however, tight constraints on payload mass and volume often preclude their launch. Employing inflatable, rigidizable structures can reduce mass and volume while providing sufficient packing flexibility and structural stiffness. AFIT has developed RIGEX to flight-test this type of structure. RIGEX will test the deployment and structural characteristics of three thermoplastic composite Sub-Tg tubes. Once launched on the Space Shuttle in 2007, the spaceflight results will be compared to lab data to validate on-orbit reliability and ground test methods. This paper documents three main …
Design And Ground-Testing Of An Inflatable-Rigidizable Structure Experiment In Preparation For Space Flight, Chad R. Moeller
Design And Ground-Testing Of An Inflatable-Rigidizable Structure Experiment In Preparation For Space Flight, Chad R. Moeller
Theses and Dissertations
As the demand for larger space structures increases, complications arise including physical dimensions, weight, and launch costs. These constraints have forced the space industry to look for smaller, more lightweight, and cost-effective solutions. Future antennas, solar sails, sun shields, and other structures have the potential to be exponentially larger than their launch envelopes. Current research in this area is focused on the use of inflatable, rigidizable structures to reduce payload size and mass, ultimately reducing launch costs. These structures can be used as booms, trusses, wings, or can be configured to almost any simple shape. More complex shapes can be …
Structural Design And Analysis Of A Rigidizable Space Shuttle Experiment, Raymond G. Holstein Iii
Structural Design And Analysis Of A Rigidizable Space Shuttle Experiment, Raymond G. Holstein Iii
Theses and Dissertations
AFIT is in the process of designing a Space Shuttle experiment designated as the Rigidized Inflatable Get-Away-Special Experiment (RIGEX) to study the effects of microgravity on the deployment of rigidizable composite structures. Once in space, the experiment will inflate and rigidize three composite structures and perform a vibration analysis on each by exciting the tubes using piezoelectric patches and collecting data via an accelerometer. This paper presents the structural and vibration analysis of the RIGEX assembly and inflatable composite tubes using ABAQUS Finite Element Analysis (FEA) software. Comparison of the analysis has been carried out with Eigenvalue/Eigenvector experimentation by means …
Characterization And Ground Test Of An Inflatable Rigidizable Space Experiment, Steven N. Lindemuth
Characterization And Ground Test Of An Inflatable Rigidizable Space Experiment, Steven N. Lindemuth
Theses and Dissertations
As greater capability is demanded of space-based assets, their size and complexity are growing. Inflatable, rigidizable structures offer significant improvements in the areas of weight, size, and complexity over traditional mechanically deployed systems. These structures are not well understood and little testing of them has been done in the space environment. Widespread acceptance of these technologies will not be achieved without significant reduction in the risk of using inflatable, rigidizable structures in space. The goal of this experiment is to verify and validate ground testing of small tubular truss structures for use in space. This experiment builds on previous research …
Rigex: Preliminary Design Of A Rigidized Inflatable Get-Away-Special Experiment, John D. Disebastian Iii
Rigex: Preliminary Design Of A Rigidized Inflatable Get-Away-Special Experiment, John D. Disebastian Iii
Theses and Dissertations
As space structures grow in size and complexity, their weight and cost increase considerably. The use of inflatable and rigidizable structures offers drastic improvements in all areas of spacecraft design. The goal of this experiment is to verify and validate ground testing of inflation and rigidization methods for inflatable space structures. The Rigidized Inflatable Get-Away-Special Experiment is an autonomous, self-contained space shuttle experiment that will inflate and rigidize several structures. After inflation, the experiment will perform a structural analysis by exciting the rigidized structures and collecting vibration data. A systems engineering approach is utilized to make design decisions based on …
Reorientations Of Flexible Spacecraft Using Momentum Exchange Devices, Kevin A. Ford
Reorientations Of Flexible Spacecraft Using Momentum Exchange Devices, Kevin A. Ford
Theses and Dissertations
We study rest-to-rest reorientations of flexible spacecraft using momentum exchange devices. A new and concise form of the equations of motion for a rigid body containing a cluster of gimbaled momentum wheels is developed using the Euler-Newton approach. Special restrictions of the gimbaled momentum wheel equations yield equations of motion for the momentum wheel cluster and the control moment gyroscope cluster. A mathematical model of a free spacecraft with Euler-Bernoulli appendages is developed. Using the assumed modes method, a complete set of equations is developed which describes the dynamics of a spacecraft with flexible appendages and gimbaled momentum wheels. Special …
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gordon C. Griffin Jr.
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gordon C. Griffin Jr.
Theses and Dissertations
A moving bank multiple model adaptive estimator-controller (MMAE-MMAC), based on linear system, quadratic cost, and Gaussian noise (LQG) assumptions, is used to quell unwanted vibrations in a large flexible space structure. The structure, known as the SPace Integrated Controls Experiment, or SPICE, exists at Phillips Laboratory, Kirtland AFB, NM. The structure consists of a large platform and a smaller platform connected by a tripod of flexible legs. The purpose of the control system is to maintain a very precise line-of- sight vector through the center of the spacecraft. Kalman filtering, used to estimate the position and velocity of the bending …
Analysis Of Modal Behavior At Frequency Cross-Over, Robert N. Costa Jr.
Analysis Of Modal Behavior At Frequency Cross-Over, Robert N. Costa Jr.
Theses and Dissertations
The existence of the mode crossing condition is detected and analyzed in the Active Control of Space Structures Model 4 (ACOSS4). The condition is studied for its contribution to the inability of previous algorithms to successfully optimize the structure and converge to a feasible solution. A new algorithm is developed to detect and correct for mode crossings. The existence of the mode crossing condition is verified in ACOSS4 and found not to have appreciably affected the solution. The structure is then successfully optimized using new analytic methods based on modal expansion. An unrelated error in the optimization algorithm previously used …
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gregory J. Schiller
Control Of A Large Space Structure Using Multiple Model Adaptive Estimation And Control Techniques, Gregory J. Schiller
Theses and Dissertations
The purpose of this thesis is to apply moving-bank multiple model adaptive estimation and control MMAEMMAC algorithms to an actual space structure SPICE being examined at Phillips Laboratory at Kirtland AFB, NM. The structure consists of a large platform and a smaller platform connected by three legs in a tripod fashion. Kalman filtering and LQG control techniques are utilized as the primary design tool. Implementing a bank of filters increases the robustness of the LQG controller when uncertainties exist in the system model, whereas the moving bank is utilized to reduce the computational load. Several reduced-order models are developed from …
Multiple Model Adaptive Control Of A Large Flexible Space Structure With Purposeful Dither For Enhanced Identifiability, James A. Fitch
Multiple Model Adaptive Control Of A Large Flexible Space Structure With Purposeful Dither For Enhanced Identifiability, James A. Fitch
Theses and Dissertations
Dithering techniques for enhancing uncertain parameter identification with moving-bank Multiple Model Adaptive Estimation MMAE and Control MMAC algorithms are analyzed in this thesis. The dithering techniques and multiple- model adaptive algorithms are applied to the SPICE 2 flexible space structure. The dithering techniques studied include purposefully constructed square wave, sine wave fixed and swept frequency and wide-band noise wave forms. Purposeful rigid-body slew commands are also used in order to excite the structures flexible bending modes. Dither inputs into the structure are performed in an effort to enhance the open-loop identifiability of the uncertain parameter, namely a scalar multiplier on …