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Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
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ItemOn-Board Model-Based Fault Diagnosis for Autonomous Proximity Operations(Georgia Institute of Technology, 2018-09) Schulte, Peter Z. ; Spencer, David A.Because of their complexity and the unforgiving environment in which they operate, aerospace vehicles often require autonomous systems to respond to mission-critical failures. Fault Detection, Isolation, and Recovery (FDIR) systems are used to detect, identify the source of, and recover from faults. Typically, FDIR systems use a rule-based paradigm for fault detection, where telemetry values are monitored against specific logical statements such as static upper and lower limits. The model-based paradigm allows more complex decision logic to be used for FDIR. This study focuses on a state machine approach toward model-based FDIR. The state machine approach is increasingly utilized for FDIR of complex systems because it is intuitive, logic-based, and simple to interpret visually. In current practice, the detection of specific symptoms is directly mapped to the appropriate response for a pre-diagnosed fault, as determined by FDIR engineers at design time. This study advances the state-of-the-art in state machine fault protection by developing an on-board diagnostic system that will assess symptoms, isolate fault sources, and select corrective actions based on models of system behavior. This state machine architecture for FDIR is applicable for a broad range of aerospace vehicles and mission scenarios. To demonstrate the broad applicability of the FDIR approach, two case studies are evaluated for scenarios in very different domains. The first is a terrestrial application involving the use of multi-rotor unmanned aerial vehicles (UAVs). The second is a space-based scenario involving autonomous proximity operations for orbital capture of a Mars Sample Return capsule. The efficacy of the state machine FDIR system is demonstrated via flight testing for the UAV case study and through software-in-the-loop testing in a flight-like simulation environment for the Mars Sample Return case. In each case, the FDIR system is focused on the Guidance, Navigation and Control subsystem. This approach has been successfully shown to detect, diagnose, and respond to faults during testing. State machines allow the autonomous system to handle distinct faults with identical symptoms for initial detection. Each fault has a separate diagnosis and response procedure, and the proper procedure is selected by the state machine. This study demonstrates how a fault protection system may diagnose these faults on-board rather than relying upon a priori ground diagnosis.
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ItemDevelopment of a Methodology for Parametric Analysis of STOL Airpark Geo-Density(Georgia Institute of Technology, 2018-06) Robinson, Joseph N. ; Sokollek, Max-Daniel ; Justin, Cedric Y. ; Mavris, Dimitri N.Vehicles designed for urban air mobility (UAM)or on-demand mobility (ODM) applications typically adopt an architecture enabling vertical takeoff and landing (VTOL) capabilities. UAM or ODM systems featuring these capabilities typically have a smaller ground footprint but are subject to a number of performance compromises that make sizing and optimizing the vehicles more challenging. These design challenges can be further compounded when additional environmental considerations are taken into account and in particular if electric propulsion is considered. Alternative architectures such as short takeoff and landing (STOL) and super-short takeoff and landing (SSTOL) vehicles are thus investigated because they present possible advantages in terms of energy efficiency, overall vehicle performance, and noise footprint. However, the larger ground footprint of the infrastructure necessary to operate these systems means that these systems may be more difficult to integrate into a urban and suburban environment. One objective of this research is to estimate the geo-density of airparks suitable for STOL and SSTOL operations based on vehicle performance and ground footprint parameters. In turn, this helps establish requirements for the field performances of STOL and SSTOL vehicles to be considered for ODM and UAM applications. This research proposes and interactive and parametric design and trade-off analysis environment to help decision makers assess the suitability of candidate cities for STOL and SSTOL operations. Preliminary results for the Miami metropolitan area show that an average airpark geo-density of 1.66 airparks per square mile can be achieved with a 300 foot long runway.
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ItemFramework to Assess Effects of Structural Flexibility on Dynamic Loads Developed in Maneuvering Aircraft(Georgia Institute of Technology, 2018-06) Sarojini, Darshan ; Duca, Ruxandra ; Solano, Heriberto D. ; Chakraborty, Imon ; Briceno, Simon ; Mavris, Dimitri N.Sizing loads for major aircraft structural components are often experienced during dynamic maneuvers, several of which are described within the Federal Aviation Regulations as part of certification requirements. A simulation and analysis framework that permits such dynamic loads to be assessed earlier in the design process is an advantage for designers and aligned with the trend towards certification by analysis. Such a framework is demonstrated in this paper using the case of a business jet performing a longitudinal checked pitch maneuver. The maneuver is simulated with a six degree-of-freedom MATLAB/Simulink simulation model, using the aircraft aerodynamic characteristics, mass properties, and an adequate level of modeling for the flight control system and pilot control action. The effects of structural flexibility and deformation of the lifting surfaces and fuselage under maneuver loads are modeled by tracking a number of structural degrees-of-freedom for each. The modular nature of the simulation setup facilitates the assessment of multiple maneuvers, analysis of sensitivity to uncertainty, as well as the identification of the impact of structural flexibility through flexible versus rigid maneuver simulations.
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ItemSimulation-based UAS Swarm Selection for Monitoring and Detection of Migrant Border Crossings(Georgia Institute of Technology, 2018-06) Harris, Caleb M. ; Sokollek, Max-Daniel ; Salas Nunez, Luis ; Valco, J.T. ; Balchanos, Michael G. ; Mavris, Dimitri N.The European migration crisis reached critical levels in 2015 due to a major influx of migrants taking the journey across the Mediterranean to Italy, Greece, and other European coasts. Migration flow rates across the Mediterranean have dropped in recent years, but fatalities have increased and border pressure is still high. Recent operations by local governments, international agencies, and NGO organizations have saved many lives and improved data collection practices, yet they have not been fully successful in responding to the high volume of travel and unexpected rate spikes in migrant trips. Different Operational Constructs and asset strategies have been studied resulting in relevant organizations investing in Unmanned Aerial Systems (UAS) for monitoring and detection. However, many questions about the most effective deployment of these assets still remain. This study is centered on the development of a modeling and simulation environment, as well as a decision support tool for conducting system-of-systems comparisons of UAS swarm and surface fleet asset combinations. The environment is an agent-based simulation built in the In-House tool Janus, which leverages the NASAWorld-Wind SDK. The simulation tool and dashboard provide a trade-off environment for parametric analysis of swarm capabilities. A case study is performed for operations by the Italian Coast Guard off the coast of Libya. Results confirm the success of implementing UAS and coordinated swarm systems. Further analysis examines the trade-off of mission effectiveness and cost, with consideration of the resilience and robustness of the system-of-systems.
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ItemA Framework for General Aviation Aircraft Performance Model Calibration and Validation(Georgia Institute of Technology, 2018-06) Puranik, Tejas G. ; Harrison, Evan D. ; Mavris, Dimitri N.A wide range of aircraft performance and safety analyses are greatly facilitated by the development and availability of reliable and accurate aircraft performance models. In an ideal scenario, the performance models would show inherently good agreement with the true performance of the aircraft. However, in reality, this is almost never the case, either owing to underlying simplifications or assumptions or due to the limited fidelity of available or applicable analysis tools. In such cases, model calibration is required in order to fine tune the behavior of available performance models to obtain the desired agreement with the truth model. In the case of point-mass steady-state performance models, challenges arise due to the fact that there is no obvious, unique metric or flight condition at which to assess the accuracy of the model predictions, and since a large number of model parameters may potentially influence model accuracy. This work presents a systematic two- level approach to aircraft performance model calibration that poses the calibration as an optimization problem using the information available. The first level consists of calibrating the performance model using manufacturer-developed performance manuals in a multi objective optimization framework. If data is available from flight testing, these models are further refined using the second level of the calibration framework. The performance models considered in this work consist of aerodynamic and propulsion models (performance curves) that are capable of predicting the non-dimensional lift, drag, thrust, and torque produced by an aircraft at any given point in time. The framework is demonstrated on two popular and representative single-engine naturally-aspirated General Aviation aircraft. The demonstrated approach results in an easily-repeatable process that can be used to calibrate models for a variety of retrospective safety analyses. An example of the safety analyses that can be conducted using such calibrated models is also presented.
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ItemModeling Airlift Operations for Humanitarian Aid and Disaster Relief to Support Acquisition Decision-Making(Georgia Institute of Technology, 2018-06) Weit, Colby J. ; Chetcuti, Steven ; Chan, Cherlyn ; Muehlberg, Marc ; Wei, Lansing ; Gilani, Hassan ; Schwartz, Katherine G. ; Sudol, Alicia M. ; Tai, Jimmy C. M. ; Mavris, Dimitri N.In a fiscally constrained environment, it is crucial that both equipment manufacturers and defence invest in technology that shows marked operational improvement. A priori identification of cost-benefit at the early acquisition stage is often limited and incomplete, leading to poor value propositions. This conundrum motivates the need to develop a method to evaluate technologies such as levels of autonomy, stealth capability, improved engines, etc. and make tradeoffs against operational measures of performance and effectiveness (MOP/Es) rather than solely against vehicle performance characteristics. The objective of this study is to create an environment in which those trades against MOEs could be performed rapidly to inform technology investment and acquisition decision-making. This environment is built on top of representative models of a discrete event simulation of disaster relief airlift operations to compare technology modifications or vehicle acquisition options rapidly against operational measures of effectiveness.
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ItemCoverage path planning for a UAS imagery mission using column generation with a turn penalty(Georgia Institute of Technology, 2018-06) Choi, Younghoon ; Choi, Youngjun ; Briceno, Simon ; Mavris, Dimitri N.This paper introduces a novel Coverage Path Planning (CCP) algorithm for a Unmanned Aerial Systems (UAS) imagery mission. The proposed CPP algorithm is a vehicle-routing-based approach using a column generation method. In general, one of the main issues of the traditional arc-based vehicle routing approaches is imposing a turn penalty in a cost function because a turning motion of vehicle requires the more amount of energy than a cruise motion. However, the conventional vehicle-routing-based approaches for the CPP cannot capture a turning motion of the vehicle. This limitation of the arc-based mathematical model comes from the property of turning motions, which should be evaluated from two arcs because a turn motion occurs at a junction of the arcs. In this paper, to mitigate the limitation, a route-based model using column generation approach with a turn penalty is proposed. To demonstrate the proposed CPP approach, numerical simulations are conducted with a conventional CPP algorithm.
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ItemRapid Assessment of Power Requirements and Optimization of Thermal Ice Protection Systems(Georgia Institute of Technology, 2018-06) Bendarkar, Mayank ; Chakraborty, Imon ; Garcia, Elena ; Mavris, Dimitri N.A thermal ice protection system prevents or dispatches ice formed on critical aircraft components like wings or nacelles by heating them either through electro-thermal or pneumatic means. The power requirements for such a system are a function of flight and atmospheric conditions and protected surface area. The developed analysis framework allows evaluation of transient and steady-state cases, anti-icing and de-icing designs, as well as evaporative and running-wet operation. To enable these analyses, a flow solver is first used to calculate local water catch efficiencies and convective heat transfer coefficients on an airfoil. These are then used within a thermal solver which evaluates water and ice accumulations over multiple control volumes under different cases of interest. This control volume approach includes both thermal and mass balances to track temperatures of the protected surface, ice, and water, as well as water/ice layer thicknesses and the water mass flow in or out of the control volume through evaporation or runback. Finally, this tool can yield power requirements for different system layouts and operating conditions, or optimize the protected surface area for a given airfoil under given operating conditions. This can help designers get an estimate of the power draw, and obtain more information on placement of the IPS on novel configurations during the design space exploration phase itself with greater fidelity and minimal computational costs.
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ItemThree-dimensional UAS trajectory optimization for remote sensing in an irregular terrain environment(Georgia Institute of Technology, 2018-06) Choi, Youngjun ; Choi, Younghoon ; Briceno, Simon ; Mavris, Dimitri N. ;This paper presents a novel algorithm for three-dimensional UAS trajectory optimization for a remote sensing mission in an irregular terrain environment. The algorithm consists of three steps: terrain modeling, the selection of scanning waypoints, and trajectory optimization. The terrain modeling process obtains a functional model using a Gaussian process from terrain information with a point cloud. The next step defines scanning waypoints based on the terrain model information, sensor specifications, and the required image resolution. For the selection of the waypoints, this paper introduces two different approaches depending on the direction of the viewing angle: a normal offset method and a vertical offset method. In the trajectory optimization, the proposed algorithm solves a distance-constraint vehicle routing problem to identify the optimum scanning route based on the waypoints and UAS constraints. Numerical simulations are conducted with two different UAS trajectory scanning methods in a realistic scenario, Point Loma in San Diego.
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ItemMethodology for Optimal Design of a Conformal Ablative Heatshield(Georgia Institute of Technology, 2018-06) Sidor, Adam T. ; Braun, Robert D. ; Kennedy, Graeme J.Conformal ablators are low density composite materials comprised of a flexible fibrous substrate and polymer matrix. Recent advancements have improved the efficiency of conformal ablator fabrication through vacuum infusion processing where resin is directly injected into a fiber substrate enclosed in a matched mold. This mold filling process can be numerically simulated to inform mold and process design. An automated methodology pairing a mold filling simulation with an approach for tiling a heatshield geometry leads to designs optimized for manufacturing. Material property estimation generalizes the approach to a range of constituent materials, enabling rapid conceptual evaluation of a conformal ablative heatshield. This work improves on the state of the art which relies on heuristic methods tailored to a particular material and aeroshell geometry. Results for a 4.5 meter, 70 degree sphere-cone aeroshell demonstrate the power of an integrated approach.