Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2015. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 151-160). / Reinforcement learning (RL) has great potential in robotic systems as a tool for developing policies and controllers in novel situations. However, the cost of realworld samples remains prohibitive as most RL algorithms require a large number of samples before learning near-optimal or even useful policies. Simulators are one way to decrease the number of required real-world samples, but imperfect models make deciding when and how to trust samples from a simulator difficult. Two frameworks are presented for efficient RL through the use of simulators. The first framework considers scenarios where multiple simulators of a target task are available, each with varying levels of fidelity. It is designed to limit the number of samples used in each successively higher-fidelity/cost simulator by allowing a learning agent to choose to run trajectories at the lowest level simulator that will still provide it with useful information. Theoretical proofs of this framework's sample complexity are given and empirical results are demonstrated on a robotic car with multiple simulators. The second framework focuses on problems represented with continuous states and actions, as are common in many robotics domains. Using probabilistic model-based policy search algorithms and principles of optimal control, this second framework uses data from simulators as prior information for the real-world learning. The framework is tested on a propeller-driven inverted pendulum and on a drifting robotic car. These novel frameworks enable RL algorithms to find near-optimal policies in physical robot domains with fewer expensive real-world samples than previous transfer approaches or learning without simulators. / by Mark Johnson Cutler. / Ph. D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1997. / Includes bibliographical references (p. 67-68). / by Julian Sell. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1991. / Includes bibliographical references (leaves 107-111). / by Laurent Paul Bonnaure. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 79-80). / This research effort presents the design and implementation of a supervisory controller for a 3DOF helicopter. This safety critical system is used in undergraduate laboratories in the Department of Aeronautics and Astronautics at MIT. There already exists a framework for designing a supervisory safety controller for motions about one axis. It is based on an analytical description of the safety region in state space. However, this framework cannot be easily extended to more complicated systems such as a 3DOF helicopter. In this thesis we present a different approach which uses a real-time simulation of linearized plant dynamics with a feedback law to ensure the system's safety. We describe the development of the system model, the design and implementation of the supervisory safety controller, integration of the safety controller as part of a remote laboratory and its evaluation based on its performance during laboratory exercises. / by Mariya A. Ishutkina. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 111-113). / Modern rocket engine turbopumps utilize cavitating inducers to meet mass and volume requirements. Rotating cavitation and higher order cavitation instabilities have frequently been observed during inducer testing and operation and can cause severe asymmetric loading on the inducer blades and shaft, potentially leading to failure of the inducer. To date no broadly applicable design method exists to characterize and suppress the onset of cavitation instabilities. This thesis presents the development of a body force model for cavitating inducers with the goal of enabling interrogation of the onset of rotating cavitation and higher order cavitation instabilities and characterization of the governing uid dynamic mechanisms. Building on body force models of gas turbine compressors for compressor stability, the model introduces an additional force component, the binormal force, to capture the strong radial flows observed in inducer ow fields. The body forces were defined and the methodology was successfully validated for two test inducers, a helical inducer and a more advanced design resembling the Space Shuttle Main Engine Low Pressure Oxidizer Pump. The head rise characteristic of each test inducer was captured with less than 4% error across the operating range and the extent of the upstream backflow region was predicted to within 18% at every operating condition. Several challenges with the blade passage model were encountered during the course of the research and the diagnostics performed to investigate them are detailed. An extension of the body force model to two-phase flows was formulated and preliminary calculations with the extended model are presented. The preliminary two-phase results are encouraging and pave the way for future assessment of rotating cavitation instabilities. / by William Alarik Sorensen. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 149-158). / The future of human space exploration will involve extra-vehicular activities (EVA) on foreign planetary surfaces (i.e. Mars), an activity that will have significantly different characteristics than exploration scenarios on Earth. These activities become challenging due to restricted vision and limitations placed on sensory feedback from altered gravity and the space suit. The use of a bulky, pressurized EVA suit perceptually disconnects human explorers from the hostile environment, increasing navigation workload and risk of collision associated with traversing through unfamiliar terrain. Due to the hazardous nature of this work, there is a critical need to design interfaces for optimizing task performance and minimizing risks; in particular, an information presentation device that can aid in obstacle avoidance during surface exploration and way-finding. Multi-modal displays are being considered as cues to multiple sensory modalities enhance cognitive processing through taking advantage of multiple sensory resources, and are believed to communicate risk more efficiently than unimodal cues. This thesis presents a wearable multi-modal interface system to examine human performance when visual, vibratory, and visual-vibratory cues are provided to aid in ground obstacle avoidance. The wearable system applies vibrotactile cues to the feet and visual cues through augmented reality glasses to convey obstacle location and proximity. An analysis of obstacle avoidance performance with the multi-modal device was performed with human subjects in a motion capture space. Metrics included completion time, subjective workload, head-down time, collisions, as well as gait parameters. The primary measures of performance were collision frequency and head-down time, as these both must be minimized in an operational environment. Results indicate that information displays enhance task performance, with the visual-only display promoting the least head-down time over tactile-only or visual-tactile displays. Head-down time was the highest for trials without a display. Results provide implications for presenting information during physically active tasks such as suited obstacle avoidance. / by Alison Eve Gibson. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1985. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO / Bibliography: leaves 93-94. / by Christopher Mark Greiner. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003. / Includes bibliographical references (p. 119-120). / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / There has been growing interest in using electronic alternatives to the paper Flight Progress Strip (FPS) for air traffic control. However, most research has been centered on radar-based control environments, and has not considered the unique operational needs of the airport air traffic control tower. Based on an analysis of the human factors issues for control tower Decision Support Tool (DST) interfaces, a requirement has been identified for an interaction mechanism which replicates the advantages of the paper FPS (e.g., minimal head-down time, portability) but also enables input and output with DSTs. An approach has been developed which uses a Portable Electronic FPS that has attributes of both a paper flight strip and an electronic flight strip. The prototype Portable Electronic Flight Progress Strip system uses handheld computers to replace individual paper strips in addition to a central management interface which is displayed on a desktop computer. Each electronic FPS is connected to the management interface via a wireless local area network. The Portable Electronic FPSs replicate the core functionality of paper flight strips and have additional features which provide an interface to a DST. A departure DST is used as a motivating example. This thesis presents the rationale for a Portable Electronic FPS system and discusses the formatting and functionalities of the prototype displays. A usability study has been conducted to determine the utility of the Portable Electronic FPS in comparison to paper flight strips. This study consisted of a human-in-the-loop experiment which simulated the tasks of an air traffic controller in an airport control tower environment. Specific issues explored during the experiment include the appropriateness of displaying departure advisories on the Portable Electronic FPS, the importance of FPS portability, and the advantages of interaction mechanisms enabled by an electronic interface. Experimental results are presented which show that test subjects preferred the Portable Electronic FPS to a paper FPS. However, results for performance-based measures were partially confounded by a dominance of practice effects, experimental limitations, and characteristics of the prototype hardware itself. The implications of the experimental results are discussed with the aim of directing further research toward the goal of creating an operationally-deployable Portable Electronic FPS system. Future research should explore emergent display technologies which better emulate the physical characteristics of the paper FPS. Once this is accomplished, higher-fidelity performance-based analyses may be conducted, engaging air traffic controllers on design and implementation issues. / by Nathan Andrew Doble. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995. / by Buford Ray Conley. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 115-118). / Traditional commercial aircraft design attempts to achieve improved performance and reduced operating costs by minimizing maximum takeoff weight, but this approach (does not guarantee the financial viability of the program to the manufacturer. Improved design practices would take into account not only aircraft performance but also financial aspects of the design. The methodology suggested herein investigates multidisciplinary design optimization (MDO) involving performance and finance jointly in aircraft program design, as well as assessment of program business risk. A value-based MDO framework couples a performance model with an improved stochastic program valuation, accounting explicitly for both uncertain demand via market volatility and managerial flexibility by invoking Real Options theory. Stochastic program value is used as the new objective for the design optimization problem. The methodology and framework developed are applied to a design example for the Blended-Wing-Body aircraft concept. Value-based optimization yields a design with a 2.3%-higher program value than that of the conventional minimum-weight solution. / (cont.) Comparing performance- and value-optimized designs, it is shown that the optimizer chooses to trade aerodynamic efficiency for reduced manufacturing costs. The effects of varying the aircraft range and speed on maximum-value solutions demonstrates that incorporating value into the design process permits more fully-informed program decisions that have optimal financial impact. Sensitivity analyses quantify the impact of technical and financial uncertainty on the stochastic value due to individual program parameters, and permit insight into the relative business risk associated with each for value-optimal designs. The results show that long-term cash flows should be emphasized over development costs. Traditional, deterministic net present value is shown to be inappropriate for use as a MDO objective function. Risk is not addressed adequately through the choice of discount rate, leading the objective to drive the optimization to make poor design tradeoffs and typically resulting in trends contrary to those of the improved stochastic valuation. Value-based MDO represents a logical progression and necessary step in the continual evolution of the aircraft design process. / by Ryan E. Peoples. / S.M.