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Daniel Guggenheim School of Aerospace Engineering

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https://hdl.handle.net/1853/70742

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College of Engineering

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Aerospace Design Group

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Aerospace Systems Design Laboratory (ASDL)

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Air Transportation Laboratory

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Cognitive Engineering Center

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Space Systems Design Laboratory (SSDL)

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Publication Search Results

Now showing 1 - 10 of 34

Prox-1 Guidance, Navigation, & Control Overview: Development, Algorithms, and Integrated Simulation

(Georgia Institute of Technology, 2014-12-01) Schulte, Peter Z.

This report describes the development and validation process of a highly automated Guidance, Navigation, & Control (GN&C) subsystem for a small satellite on-orbit inspection application. The resulting GN&C subsystem performs proximity operations (ProxOps) without human-in the-loop interaction. The report focuses on the description of the GN&C algorithms, the integration and testing of GN&C software, and the development of decision logic to address the question of how such a system can be effectively implemented for full automation. This process is unique because a multitude of operational scenarios must be considered and a set of complex interactions between various GN&C components must be defined to achieve the automation goal. The GN&C subsystem for the Prox-1 satellite is currently under development within the Space Systems Design Laboratory at the Georgia Institute of Technology. The Prox-1 mission involves deploying the LightSail 3U CubeSat, entering into a leading or trailing orbit of LightSail using ground-in-the-loop commands, and then performing automated ProxOps through formation flight and natural motion circumnavigation maneuvers. Operations such as these may be utilized for many scenarios including on-orbit inspection, refueling, repair, construction, reconnaissance, docking, and debris mitigation activities. Prox-1 uses onboard sensors and imaging instruments to perform its GN&C operations during on-orbit inspection of LightSail. Navigation filters perform relative orbit determination based on images of the target spacecraft, and guidance algorithms conduct automated maneuver planning. A slew and tracking controller sends attitude actuation commands to a set of control moment gyroscopes, and other controllers manage desaturation, detumble, and target acquisition/recovery. All Prox-1 GN&C components are developed in a MATLAB/Simulink six degree-of-freedom simulation environment and are integrated using decision logic to autonomously determine when certain actions should be performed. The complexity of this decision logic is the main challenge of this process, and the Stateflow tool in Simulink is used to establish logical relationships and manage data flow between each of the individual GN&C hardware and software components. Once the integrated GN&C simulation is fully developed in MATLAB/Simulink, the algorithms are autocoded to C/C++ and integrated into flight software. The subsystem is tested using hardware-in-the-loop on the flight computers and other hardware
Design and Development of RED-Data2: A Data Recording Reentry Vehicle

(Georgia Institute of Technology, 2014-08-01) Sidor, Adam T.

Defunct, manmade objects in orbit regularly reenter Earth’s atmosphere in an uncon trolled manner causing risk of both personal injury and property damage. To reduce uncertainty and improve our ability to predict surviving debris, impact time and impact location, reentry breakup dynamics and aerothermodynamics data is needed. The Reentry Breakup Recorder has demonstrated the ability to obtain inertial and thermal measure ments during reentry that are pertinent to spacecraft breakup. Building on this concept, the present investigation explores the design space for this device and matures a smaller, lighter and more operationally flexible system, termed RED-Data2.
A Comparison of Three Algorithms for Orion Drogue Parachute Release

(Georgia Institute of Technology, 2014-04-28) Matz, Daniel A.

The Orion Multi-Purpose Crew Vehicle is susceptible to flipping apex forward between drogue parachute release and main parachute inflation. A smart drogue release algorithm is required to select a drogue release condition that will not result in an apex forward main parachute deployment. The baseline algorithm is simple and elegant, but does not perform as well as desired in drogue failure cases. A simple modification to the baseline algorithm can improve performance, but can also sometimes fail to identify a good release condition. A new algorithm employing simplified rotational dynamics and a numeric predictor to minimize a rotational energy metric is proposed. A Monte Carlo analysis of a drogue failure scenario is used to compare the performance of the algorithms. The numeric predictor prevents more of the cases from flipping apex forward, and also results in an improvement in the capsule attitude at main bag extraction. The sensitivity of the numeric predictor to aerodynamic dispersions, errors in the navigated state, and execution rate is investigated, showing little degradation in performance
Preliminary Design Study of Asymmetric Hypersonic Inflatable Aerodynamic Decelerators for Mars Entry

(Georgia Institute of Technology, 2014-04-28) Harper, Brooke P.

The Mars missions envisioned in the future require payload mass in excess of the current capable limit for entry vehicle technology. Deployable Hypersonic Inflatable Aerodynamic Decelerators offer one solution to successfully improve drag performance and reduce ballistic coefficient to mitigate entry, descent, and landing concerns as payload mass increases. The majority of the research that has been conducted on these structures thus far only focuses on axisymmetric geometries. In this investigation, aerodynamic and aerothermodynamic performance is examined for three proposed asymmetric families that can generate non-zero lift-to-drag ratios at 0° angle of attack and are compared to a symmetric counterpart. Ideal results include favorable lift-to-drag ratios with reduced ballistic coefficients. The blunt, asymmetric Hypersonic Inflatable Aerodynamic Decelerator designs considered are assembled from stacked tori configurations with a base diameter of 20 m and the capability to interface with a 10 m diameter rigid center body. The configurations reviewed are capable of producing hypersonic lift-to-drag ratios between ~0.1 and ~0.6 for angles of attack ranging from -30° to 20°. A 40 Mt entry mass, approximate mass of large robotic or human scale mission is assumed. Advantageous ballistic coefficient data is retrieved for some asymmetric geometries. All HIAD configurations are determined to be statically stable as well. An initial assessment of the aerothermodynamic response predicts significant heating with radiative heating being much greater than convective heating. From the analyses completed thus far, encouraging results project asymmetric Hypersonic Inflatable Aerodynamic Decelerators as conceivable candidates for future large scale Mars missions
Parachute Dynamic Stability and the Effects of Apparent Inertia

(Georgia Institute of Technology, 2014-02-12) Ginn, Jason M.

The dynamic stability and equilibrium conditions of a parachute are studied using a six degree of freedom dynamic model that includes apparent inertia effects. A dynamic model that incorporates apparent inertia is described and used for analysis. The moments on the parachute system caused by the apparent inertia term are shown to affect both the equilibrium point and the stability of the system. The adjustment to equilibrium is observed and discussed. A small disturbance stability analysis is performed to give stability criteria. The dynamic modes, pitching and coning, are discussed. Computational integration of the equations of motion is used to validate the small disturbance analysis as well as to show the effects of large disturbances. An example stability analysis and nonlinear simulation are performed for a ringsail system for Mars entry.
Investigation of Drag Modulated Supersonic Inflatable Aerodynamic Decelerators for Use on Sounding Rocket Payloads

(Georgia Institute of Technology, 2013-12-13) Miller, Matthew J.

This paper presents an assessment of use of a supersonic inflatable aerodynamic decelerator for drag modulation of a sounding rocket payload bus structure as part of a high-altitude sample return mission. The scientific goal of this mission is to capture mesospheric dust and particulate matter located 45 km to 85 km in altitude. This mission is also to demonstrate technology that is capable of precise landings by combining a decelerator system comprised of inflatable aerodynamic decelerator to reach within 10 km with a guided parafoil system. Three decelerator configurations, the tension cone, attached isotensoid, and the trailing isotensoid, were examined on the metrics of decelerator mass, aerodynamic performance, and vehicle integration. The attached isotensoid was found to be the most mass efficient option, while the trailing isotensoid was determined to be preferable from an overall system level perspective. The decelerators’ precision landing capability through the use of drag modulation was also evaluated. Downrange error was reduced by 21% by drag modulation as compared to an 8.5 m supersonic disk-gap-band parachute. When coupled with a guided parafoil, drag modulation provides a 95% confidence level in landing within the 10 km parafoil capability region, and a 76% confidence level of landing within 5 km of the target.
Supersonic Propulsive Divert Maneuvers for Future Robotic and Human Mars Missions

(Georgia Institute of Technology, 2013-12-13) Mandalia, Amit B.

Future robotic and human missions to Mars require improved landed precision and increased payload mass. Two architectures that seek to meet these requirements using supersonic propulsive diverts are proposed in this paper: one utilizing a high-altitude propulsive divert and another with thrust vectoring during supersonic retropropulsion. Low ballistic coefficient entry vehicles decelerate high in the thin Mars atmosphere and may be used to deliver higher-mass payloads to the surface. A high-altitude supersonic propulsive divert maneuver is proposed as a means of precision landing for low ballistic coefficient entry vehicles that decelerate to supersonic speeds at altitudes of 20-60 km. This divert maneuver compares favorably to traditional precision landing architectures with up to 100% improvement in range capability while saving over 30% in propellant mass. Architectures which utilize hypersonic vehicles with ballistic coefficients of 10 kg/m2 were found to land within 500 m of a target with this maneuver alone. This high-altitude divert range capability is sensitive to altitude and flight-path angle variations at maneuver initiation and relatively insensitive to velocity at initiation. Propellant mass fraction is relatively invariant to the initial conditions and correlates directly with the divert distance. Supersonic retropropulsion has also been proposed as a means to deliver higher-mass payloads to the surface, and thrust vectoring during supersonic retropropulsion can save a substantial amount of fuel in a precision landing scenario. Propellant mass savings greater than 30% are possible if thrust vectoring is unconstrained during the supersonic phase of flight. Propellant mass fraction is found to be sensitive to the divert direction and also the altitude and flight-path angle, favoring low altitudes and shallow flight-path angles.
Flexible Thermal Protection System Physics-Based Modeling for Temperature Profile Predictions

(Georgia Institute of Technology, 2013-12-03) Rossman, Grant A.

Candidate material testing was performed on various Flexible Thermal Protection Systems (FTPS) layup configurations in an arc-jet ground test facility. A physics-based thermal model was created to predict the thermal-material response of each FTPS layup under arc-jet induced thermal loading. Initial thermal model temperature predictions of embedded thermocouples for FTPS test articles showed an unsatisfactory correlation to arc jet test data. The Levenberg-Marquardt (LM) inverse parameter estimation technique was implemented to reduce discrepancies between thermal model temperature predictions and experimental thermocouple temperature measurements by iteratively modifying FTPS thermal parameters within the model, such as thermal conductivity and specific heat. A formal parameter estimation methodology, previously applied for ablative TPS, is applied to this FTPS problem to improve understanding estimation behavior and LM error minimization. Nominal, uncertainty, sensitivity, and inverse analysis are performed on scaled thermal inputs to provide insight on solution uniqueness and stability. This error minimization technique is demonstrated on a previously flown FTPS layup configuration consisting of two outer fabric layers, two insulation layers, and one gas barrier layer. Results show that the LM method is a viable technique for inverse parameter estimation of FTPS thermal modeling problems.
Aerodynamic Stability and Performance of Next-Generation Parachutes for Mars Descent

(Georgia Institute of Technology, 2013-07-18) Gonyea, Keir

The aerodynamic stability and performance characteristics of next-generation supersonic parachutes were determined through wind tunnel testing. Canopy configurations included the disk-gap-band (DGB), ringsail, and ringsail-variant designs referred to as the disksail and starsail. Stereo photogrammetric processing was performed during testing, which was then used to estimate the static and dynamic moment coefficient curves as a function of total angle of attack. The dynamic components of the angle of attack and sideslip angle were shown to be significant, heavily influencing the resulting total angle of attack profile and moment coefficients. Uncertainty in the apparent mass of the canopies resulted in uncertainty in the moment coefficient magnitudes. From the stability curves, the peak moment, trim total angle of attack, and pitch stiffness at the trim angle could be determined. Parachute stability was assessed in the context of drag load and geometric porosity. An inverse relationship between the drag load and the stability of the canopies was generally seen. The DGB canopies tended to be more stable while the ringsail and disksail canopies had more drag. Similar stability properties as the DGB with slightly higher drag loads were obtained by increasing the geometric porosity distribution around the crown of the disksail canopies.
Photogrammetry Analysis of a Hypersonic Inflatable Aerodynamic Decelerator Structural Test Article

(Georgia Institute of Technology, 2013-07-11) Li, Lin

Analysis was performed on photogrammetry data of a 6m Hypersonic Inflatable Aerodynamic Decelerator (HIAD), an inflatable stacked torus used to aid in atmospheric entry, to understand its structural dynamics. Photogrammetry data was obtained during wind tunnel testing under various loading conditions. Test parameters included the freestream dynamic pressure, yaw angle and internal inflation pressure. In addition, two HIAD configurations were analyzed, the basic stacked torus (Baseline configuration) and a second configuration adding a torus near the shoulder to aid in rigidity (Tri-Tori configuration). The analysis includes estimating the deflection of the HIAD under loading as well as calculating the standard deviation relative to the mean deflection and the frequency content of the dynamic response. Under load, the deflection angle for each configuration ranged from 1° to 3° (1σ). Analysis of the results indicates that the Tri-Tori configuration did not demonstrate significant benefit over the Baseline. The photogrammetry data showed that the oscillatory motion increased with higher dynamic pressure but was insensitive to yaw angle. In addition, the analysis showed that the standard deviation of the HIAD shape with respect to the average deflection increased while moving radially outwards. However, the standard deviation values calculated from different camera pairs were inconsistent and did not produce the same standard deviations especially at the interface region. The frequency analysis showed that each radial member behaved similarly to a rigid oscillator, having the same frequency content of motion along each radial direction and increased amplitude when moving radially outward. Both the frequency and shape standard deviation analyses showed that the motion of the HIAD was piecewise continuous in the azimuthal direction. These discontinuities likely arose when stitching together the images from different camera pairs. The photogrammetry data is a valuable dataset providing insight into the static and dynamic response of the HIAD under loading. However, inconsistencies in the camera imaging and stitching need to be resolved and higher temporal resolution will improve the fidelity of analysis