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Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
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ItemTesting the effects of violating component axioms in validation of complex aircraft systems(Georgia Institute of Technology, 2014-12-08) Kansal, AparnaThis thesis focuses on estimating faults in complex large-scale integrated aircraft systems, especially where they interact with, and control, the aircraft dynamics. A general assumption considered in the reliability of such systems is that any component level fault will be monitored, detected and corrected by some fault management capability. However, a reliance on fault management assumes not only that it can detect and manage all faults, but also that it can do so in sufficient time to recover from any deviation in the aircraft dynamics and flight path. Testing for system-level effects is important to ensure better reliability of aircraft systems. However, with existing methods for validation of complex aircraft systems, it is difficult and impractical to set up a finite test suite to enable testing and integration of all the components of a complex system. The difficulty lies in the cost of modelling every aspect of every component given the large number of test cases required for sufficient coverage. Just having a good simulator, or increasing the number of test cases is not sufficient; it is also important to know which simulation runs to conduct. For this purpose, the thesis proposes simulating faults in the system through the violation of “axiomatic conditions” of the system components, which are conditions on the functioning of these components introduced during their development. The thesis studies the effect, on the aircraft dynamics, of simulating such faults when reference models of the components representing their key functions are integrated.
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ItemDeveloping a computational model of the pilot's best possible expectation of aircraft state given vestibular and visual cues(Georgia Institute of Technology, 2014-12-05) Onur, CanLoss of Control (LOC) accidents are a major threat for aviation, and contribute the highest risk for fatalities in all aviation accidents. The major contributor to LOC accidents is pilot spatial disorientation (SD), which accounts for roughly 32% of all LOC accidents. A pilot experiences SD during flight when the pilot's expectation of the aircraft's state deviates from reality. This deviation results from a number of underlying mechanisms, such as distraction, failure to monitor flight instruments, and vestibular illusions. Previous researchers have developed computational models to understand those mechanisms. However, these models are limited in scope as they do not model the pilot's knowledge of the aircraft dynamics. This research proposes a novel model to predict the best-possible-pilot-expectation of the aircraft state given vestibular and visual cues. The proposed model uses a Model-Based Observer (MBO) as the infrastructure needed to establish an “expert pilot”. Expert pilots are known to form an internal model of the operated system through training and experience, which allows the expert to generate better internal expectations of the system states. Pilots' internal expectations are enhanced by the presence of information fed through the pilots̕ sensory systems. Thus, the proposed model integrates pilot's knowledge of the system dynamics (i.e. an aircraft model) with a continuous vestibular sensory model and a discrete visual-sampling sensory model. The computational model serves to investigate the underlying mechanisms of SD during flight and provide a quantitative analysis tool to support flight deck and countermeasure designs.
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ItemPreparing students to incorporate stakeholder requirements in aerospace vehicle design(Georgia Institute of Technology, 2014-04-04) Coso, Alexandra EmelinaThe design of an aerospace vehicle system is a complex integration process driven by technological developments, stakeholder and mission needs, cost, and schedule. The vehicle then operates in an equally complex context, dependent on many aspects of the environment, the performance of stakeholders and the quality of the design itself. Satisfying the needs of all stakeholders is a complicated challenge for designers and engineers, and stakeholder requirements are, at times, neglected in design decisions. Thus, it is critical to examine how to better incorporate stakeholder requirements earlier and throughout the design process. The intent of this research is to (1) examine how stakeholder considerations are currently integrated into aerospace vehicle design practice and curricula, (2) design empirically-informed and theoretically-grounded educational interventions for an aerospace design capstone course, and (3) isolate the characteristics of the interventions and learning environment which support students’ integration of stakeholder considerations. The first research phase identified how stakeholder considerations are taken into account within an aerospace vehicle design firm and in current aerospace engineering design curricula. Interviews with aerospace designers revealed six conditions at the group, interaction and individual levels affecting the integration of stakeholder considerations. Examining current curricula, aerospace design education relies on quantitative measures. Thus, many students are not introduced to stakeholder considerations that are challenging to quantify. In addition, at the start of an aerospace engineering senior design capstone course, students were found to have some understanding of the customer and a few contextual considerations, but in general students did not see the impact of the broader context or of stakeholders outside of the customer. The second research phase comprised the design and evaluation of a Requirements Lab and Stakeholders in Design Labs, two in-class interventions implemented in a senior aircraft design capstone course. Further, a Stakeholders in Design rubric was developed to evaluate students’ design understanding and integration of stakeholder considerations and, as such, can be used as a summative assessment tool. The two interventions were evaluated using a multi-level framework to examine student capstone design projects, a written evaluation, and observations of students’ design team meetings. The findings demonstrated an increase in students’ awareness of a diverse group of stakeholders, but also perceptions that students appeared to only integrate stakeholder considerations in cases where interactions with stakeholders were possible and the design requirements had an explicit stakeholder focus. Particular aspects of the aircraft design learning environment such as the lack of explicit stakeholder requirements, the differences between the learning environment in the two semesters of the course, and the availability of tools impacted students’ integration of stakeholder considerations and overall effectiveness of the interventions. This research serves as a starting point for future research in pedagogical techniques and assessment methods for integrating stakeholder requirements into technology-focused design capstone courses. The results can also inform the vehicle design education of students and engineers from other disciplines.
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ItemDeveloping a training program for the traffic alert and collision avoidance system in context(Georgia Institute of Technology, 2013-03-26) Fleming, Elizabeth ScottThe Traffic alert and Collision Avoidance System (TCAS) is an aircraft collision avoidance system designed to prevent mid-air collisions. During an advisory, danger is imminent, and TCAS is assumed to have better, more up-to-date information than the ground operated air traffic control (ATC) facility. Following a TCAS RA is generally the safe course of action during an advisory. However, pilot compliance with RAs is surprisingly low. Results from a TCAS monitoring study show pilots are not complying with many TCAS advisories. As revealed by pilot-submitted Aviation Safety Reporting System (ASRS) reports, this noncompliance could be attributed, in part, to pilot confusion to TCAS operation as well as misunderstandings of the appropriate response to a TCAS issued advisory. This thesis details the development and evaluation of a TCAS training program intended to improve pilots' understanding of TCAS use for collision avoidance in a range of traffic situations. The training program integrated Demonstration Based and Event Based Training techniques. Its efficacy was analyzed in an integrated ATC-cockpit simulator study in which eighteen commercial airline pilots were asked to complete the TCAS training program and afterwards experienced twelve experimental traffic events. The trained pilots' performance was compared to the performance of 16 baseline pilots who did not receive the modified training. Overall, the training program did have a significant impact on the pilots' behavior and response to TCAS advisories. The measure Time Pilots First Achieved Compliance decreased with the trained pilots, as did the measure Autopilot Disconnect Time After RA Initiation. Trained pilots exhibited less aggressive performance in response to a TCAS RA (including a decrease in the measures Altitude Deviation Over Duration Of RA, Average Vertical Rate Difference, Maximum Vertical Rate Difference, and Maximum Vertical Rate). The measure Percent Compliance did not significantly vary between trained and baseline pilots, although trained pilots had a more consistent response in the traffic event with conflicting ATC guidance. Finally, on the post-experiment questionnaires, pilots commented on their increase in understanding of TCAS as well as an increase in their trust in the advisory system. Results of this research inform TCAS training objectives provided by the FAA as well as the design of TCAS training. Additionally, conclusions extend more broadly to improved training techniques for other similar complex, time-critical situations.
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ItemAn evaluation of interval management (IM) using task analysis and work domain analysis(Georgia Institute of Technology, 2013-01-04) Swieringa, Kurt A.Work Domain Analysis (WDA) and task analysis are methods that can be used to develop complex systems that support human operators. Task analysis can be used to describe the nominal tasks of many complex safety critical systems which are also highly proceduralized. However, complex systems may require human operators to have a greater understanding of the system's dynamics than can be obtained from procedures derived from a task analysis. This is particularly true when off-nominal events occur, for which there is no procedure. By concentrating on the constraints in the work domain instead of tasks, work domain analysis can complement task analysis by supporting operators during off-nominal events that do not have any predescribed procedures. The goal of this study was to use WDA and two forms of task analysis to derive interface and procedure modifications for a new aviation concept called interval management. Interval management is a new concept whose goal is to increase runway throughput by enabling aircraft to achieve a precise interval behind a lead aircraft. This study used data from a human-in-the-loop study conducted at NASA Langley Research Center to develop a Hierarchical Task Analysis (HTA), Control Task Analysis (CTA), and WDA. The HTA was used to describe a nominal set or procedures, the CTA was used to describe strategies pilots could use to make decisions regarding the IM operation, and the WDA was used to determine representations and procedures that could convey complete and accurate knowledge of interval management to the flightcrew.
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ItemImproving pilot understanding of TCAS through the traffic situation display(Georgia Institute of Technology, 2013-01-02) Cleveland, William PeterThe goal of this thesis is to improve pilot understanding of the Traffic alert and Collision Avoidance System (TCAS) by changing the Traffic Situation Display (TSD). This is supported by two objectives. The first objective is to create an integrated, realistic air traffic environment. This serves as an experimental platform for testing and evaluating future TCAS TSDs. The simulator environment includes a desktop flight simulator, background air traffic simulator, and intruder aircraft. The intruder aircraft uses seven dimensional waypoints to robustly follow trajectories and cause specific resolution advisories. Second, the relative benefits of, and potential concerns with, new TCAS TSDs are explored using a structured, iterative design process with subject matter ex- perts (SMEs). Incremental changes to the TSD were implemented into the simulator environment. SMEs evaluated the displays and potential points of confusion were identified. Several display features are discussed and implemented for future evaluations. These include boundary lines of TCAS variables depicted on the TSD and on a vertical situation display, speed lines which vary with the TCAS estimate of time to closest point of approach, and a prediction of the safe altitude target during a resolution advisory. Scenarios which may be confusing or misleading are discussed. These scenarios may be ameliorated or exacerbated by display features. This information is useful to guide both design and certification or operational approval and is a starting place for future TCAS experiments.
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ItemModel-based metrics of human-automation function allocation in complex work environments(Georgia Institute of Technology, 2011-07-08) Kim, So YoungFunction allocation is the design decision which assigns work functions to all agents in a team, both human and automated. Efforts to guide function allocation systematically has been studied in many fields such as engineering, human factors, team and organization design, management science, and cognitive systems engineering. Each field focuses on certain aspects of function allocation, but not all; thus, an independent discussion of each does not address all necessary issues with function allocation. Four distinctive perspectives emerged from a review of these fields: technology-centered, human-centered, team-oriented, and work-oriented. Each perspective focuses on different aspects of function allocation: capabilities and characteristics of agents (automation or human), team structure and processes, and work structure and the work environment. Together, these perspectives identify the following eight issues with function allocation: 1)Workload, 2)Incoherency in function allocations, 3)Mismatches between responsibility and authority, 4)Interruptive automation, 5)Automation boundary conditions, 6)Function allocation preventing human adaptation to context, 7)Function allocation destabilizing the humans' work environment, and 8)Mission Performance. Addressing these issues systematically requires formal models and simulations that include all necessary aspects of human-automation function allocation: the work environment, the dynamics inherent to the work, agents, and relationships among them. Also, addressing these issues requires not only a (static) model, but also a (dynamic) simulation that captures temporal aspects of work such as the timing of actions and their impact on the agent's work. Therefore, with properly modeled work as described by the work environment, the dynamics inherent to the work, agents, and relationships among them, a modeling framework developed by this thesis, which includes static work models and dynamic simulation, can capture the issues with function allocation. Then, based on the eight issues, eight types of metrics are established. The purpose of these metrics is to assess the extent to which each issue exists with a given function allocation. Specifically, the eight types of metrics assess workload, coherency of a function allocation, mismatches between responsibility and authority, interruptive automation, automation boundary conditions, human adaptation to context, stability of the human's work environment, and mission performance. Finally, to validate the modeling framework and the metrics, a case study was conducted modeling four different function allocations between a pilot and flight deck automation during the arrival and approach phases of flight. A range of pilot cognitive control modes and maximum human taskload limits were also included in the model. The metrics were assessed for these four function allocations and analyzed to validate capability of the metrics to identify important issues in given function allocations. In addition, the design insights provided by the metrics are highlighted This thesis concludes with a discussion of mechanisms for further validating the modeling framework and function allocation metrics developed here, and highlights where these developments can be applied in research and in the design of function allocations in complex work environments such as aviation operations.
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ItemExamining the relative costs and benefits of shifting the locus of control in a novel air traffic management environment via multi-agent dynamic analysis and simulation(Georgia Institute of Technology, 2011-06-28) Bigelow, Matthew StevenThe current air traffic management system has primarily evolved via incremental changes around historic control, navigation, and surveillance technologies. As a result, the system as a whole is not capable of handling air traffic capacities well beyond current levels, despite recent developments, such as ADS-B, that could potentially enable new concepts of operation. Methods of analyzing air traffic for safety and performance have also evolved around current-day operating constructs. Thus, attempts to examine future systems tend to use different analysis methods developed for each. Most notably, questions of 'locus of control' - whether the control should be centralized or de-centralized and distributed - have no common framework by which to judge relative costs and benefits. For instance, a completely centralized control paradigm is commonly asserted to provide an airspace-wide optimal traffic management solution due to a more complete picture of the state of the airspace, whereas a completely decentralized control paradigm is commonly asserted to provide a more user-specific optimal traffic management solution, to distribute the traffic management workload, and potentially be more robust. Given the disparate nature of these assertions and the different types of evaluations commonly used with each, some shared framework must be established to allow comparisons between very different control paradigms. The objective of this thesis was to construct a formal framework to examine the relative costs and benefits of shifting the locus of control in a novel air traffic management environment. This framework provides useful definitions and quantitative measures of flexibility and robustness with respect to various control paradigms ranging between, and including, completely centralized and completely decentralized concepts of operation. Multi-agent dynamic analysis and simulation was used to analyze the range of dynamics found in the different control paradigms. In addition, futuristic air traffic management concepts were developed in sufficient detail to demonstrate the framework. In other words, the objectives were met because the framework was demonstrated to have the ability to identify (or dispel) hypotheses about the relative costs and benefits of locus of control.