Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995. / Includes bibliographical references (p. 117-119). / by Amy Jean McCain. / M.S.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007. / Includes bibliographical references (p. 151-156). / This thesis develops a mission planning and scheduling algorithm that enables a single Unmanned Undersea Vehicle (UUV) to concurrently perform high level activities, while managing various resources in a dynamic ocean environment. Such activities may include wide area surveillance of a specified region and focused inspection tasks. Concurrent execution of activities allows a UUV to perform portions of different activities that share overlapping regions consecutively to increase vehicle productivity. Resources considered in this algorithm range from concrete quantities, such as the remaining battery energy, to variables representing operational restrictions, such as the maximum allowable navigation uncertainty. The first step in the development defines a parameterization that describes each high level activity in terms of smaller atomic tasks. In order to determine a sequence/path of tasks for the UUV to perform, a Prize Winning Salesman Problem with Replenishment Arcs (PW-RATSP) formulation transforms the set of atomic tasks into a set of nodes representing sequences of non-resource-replenishment tasks and a set of arcs that represent sequences of resource-replenishment tasks. The algorithm then expresses and solves the PWRATSP formulation as a mixed integer linear program (MILP). Finally, the algorithm employs a receding horizon approach to improve MILP computational performance and account for unexpected events and changes to the environment. Simulation results for test cases combining surveillance and inspection activities, and multiple resource replenishment activities show that the PW-RATSP UUV mission planning algorithm provides the ability to manage concurrent activities, perform temporal reasoning, and account for a mix of replenishable and non-replenishable vehicle resources. / by Larry Chang. / S.M.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1996. / Includes bibliographical references (p. 95-97). / by John Matthew Kerwin. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1989. / Includes bibliographical references (leaves 130-132). / by Patrick Hanley. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007. / Includes bibliographical references (p. 63-65). / Astronauts perform space teleoperation tasks with visual feedback from outside cameras. Individuals differ greatly in the ability to integrate camera views, understand the workspace, and ensure clearances between the robot arm and obstacles. We believe that these individual differences correlate with two known subcomponents of spatial intelligence: perspective-taking (PT) and spatial visualization (SV). A preliminary study [1] supports this hypothesis. We believe astronauts use PT (the ability to imagine an object from a different viewpoint) to integrate camera information into an environmentally-referenced frame defined by the arm control axes. In some cases, it may be easier to visualize the manipulation of the payload with respect to the robot arm itself, than to the environment. In that case, SV(i.e., the ability to mentally manipulate an object from an egocentric perspective) may be exploited. We measured the performance of 25 naive subjects who used hand-controllers to rotate and translate, and 3 environmentally-fixed camera views. These devices controlled a 2-boom, 6 degree-of-freedom virtually-simulated arm to perform pickup and docking subtasks. / (cont.) To challenge the subjects' spatial ability we introduced a wide separation between camera views for some tests, and misalignments between the translation control and the display reference frames. We used the Perspective-Taking Ability test (PTA) and the Purdue Spatial Visualizations Test: Visualization of Views (PSVT:V) to measure PT, and the Cube Comparisons test (CC) to assess SV. We concluded that PTA predicted performance on pickup and docking subtasks, but PSVT:V did not. CC scores correlated with those measures of performance that did not necessarily require PT. High perspective-taking scorers performed the pickup task significantly more efficiently than low, but not faster. In docking, however, they were both significantly faster and more accurate, collided less often, and docked more accurately. In both tasks they moved along only one axis at a time. High CC scorers docked significantly more accurately and rotated about fewer axes at any one time. Whenever we found a significant effect of PSVT:V on a dependent variable, we also found one for PTA; but not the reverse. / (cont.) We had expected higher PT scorers to perform better than others under the challenge of wider camera angles and greater control-display frame misalignments, but we could not demonstrate this. On average females were slower and had lower docking accuracy, an effect related, perhaps, to their lower spatial ability scores. This study of performance during the first two hours of teleoperation training may help define issues for future research. / by María Alejandra Menchaca Brandan. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2002. / Includes bibliographical references (p. 90-91). / by Geoffroy Lenglin. / S.M.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2013. / This thesis was scanned as part of an electronic thesis pilot project. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 181-187). / After centuries of studying the eight planets in our solar system, recent improvements in technology have given us the unprecedented opportunity to detect planets orbiting stars other than the sun, so-called exoplanets. Recent statistical studies based on 800 confirmed planets and more than 3000 planet candidates suggest that our galaxy is teeming with billions of planets. Many of them are likely to orbit their host stars at a distance where liquid water and potentially life can exist. Spectroscopic observations of exoplanets can provide us with information about the atmospheres and conditions on these distant worlds. This thesis presents a Bayesian retrieval framework to analyze spectroscopic observations of exoplanets to infer the planet's atmospheric compositions, the surface pressures, and the presences of clouds or hazes. I identify what can unambiguously be determined about the atmospheres of exoplanets by applying the retrieval method to sets of synthetic observations. The main finding is that a unique constraint of the atmospheric mixing ratios of all infrared absorbing gases and up to two spectrally inactive gases is possible if the spectral coverage of the observations is sufficient to (1) determine the broadband transit depths in at least one absorption feature for each absorbing gas and (2) measure the slope and strength of the molecular Rayleigh scattering signature. For the newly discovered class of low-density super-Earths, with radii and masses intermediate between Earth and Neptune, I present an observational approach to distinguish whether these planets more closely resemble the giant planets in our solar system or whether they represent a completely new, potentially water vapor-rich type of planet. The approach discussed in this work represents the science case for the largest Hubble Space Telescope program ever awarded for a single exoplanet. The numerical methods and the conceptual understanding of atmospheric spectra presented in this thesis are key for the design of future space telescopes dedicated to the characterization of transiting exoplanets. I present an integrated design evaluation framework for the proposed Exoplanet Characterization Observatory (EChO) that simultaneously models the astrophysical signal and the telescope's payload module. I demonstrate that costly cryogenic cooling to observe the mid-infrared spectrum beyond ~ 11 [mu]m is not required while visible light observations down to - 400 nm are essential for the mission success. The observational study of exoplanet atmospheres is in its infancy and its pace is poised to accelerate as observational techniques are improved and dedicated space missions are designed. The methods developed in this thesis will contribute to constraining the atmospheric properties of a wide variety of planets ranging from blazingly-hot gas giants to temperate Earth-like planets. / by Björn Benneke. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003. / Includes bibliographical references (leaves 66-69). / by Jun Luo. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000. / Also available online at the MIT Theses Online homepage <http://thesis.mit.edu>. / Includes bibliographical references. / The goal of this research is to characterize the distribution and costs of spacecraft discrepancies found at the system level of integration and test, as well as understand the implications of those distributions and costs for the spacecraft enterprise as a whole. If discrepancies can be better understood, they can potentially be reduced or even eliminated. Reducing discrepancies will result in cycle time reduction and cost savings, as well as increased product quality and reliability. All of these potential outcomes are indications of successful progress toward becoming a lean organization. Data on discrepancies at the system level of integration were gathered from spacecraft vendor databases, while interviews with key program managers and engineers provided perspective and insight into the data. Results are based on 224 spacecraft representing at least 20 different programs or product lines, and encompassing 23,124 discrepancies. The spacecraft date from 1973-1999, and represent different vendors as well as a mix of commercial and government spacecraft. Spacecraft discrepancies are analyzed in this work on the basis of ten categories: the spacecraft mission, the spacecraft subsystem where the discrepancy occurred, the date of the discrepancy occurrence, the discrepancy report open duration, the immediate action taken to fix the discrepancy (disposition), the root cause of the discrepancy, the long-term corrective action prescribed to prevent the discrepancy from happening again on future spacecraft, the labor time spent on the discrepancy, and the cycle time lost due to the discrepancy. Statistical measures of central tendency, correlation and normality are presented for each category. This statistical analysis forms the basis for research findings at the enterprise level in the areas of quality yield, resource utilization, stakeholder satisfaction and flow time. Recommendations to enterprise stakeholders for increasing the value derived from system-level integration and test follow from the enterprise-level findings. / by Annalisa L. Weigel. / S.M.

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 87-92). / While measurement covariances are often taken to be constant in many robotic state estimation systems, many sensors exhibit different interactions with their environment. Accurate covariance estimation allows graph-based estimation techniques to better optimize state estimates by reasoning about the utility of different methods relative to each other. This thesis describes a method of learning compact feature representations for real-time covariance estimation. A direct log-likelihood optimization technique is used to train a deep convolutional neural network to predict the covariance matrix of a Gaussian measurement model, given representative data. This method is algorithm-agnostic, and therefore does not require the handcoding of representative features. Quantative results are presented, showing that improved measurement covariances on a frame-to-frame visual odometry system reduce trajectory errors after a loop closure is applied. / by Katherine Y. Liu. / S.M.