+publisher:"University of Colorado" +contributor:("Jay W. McMahon")

University of Colorado

1. Iglesias Echevarria, David I. Cooperative Robot Localization Using Event-Triggered Estimation.

Degree: MS, 2017, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/185

► It is known that multiple robot systems that need to cooperate to perform certain activities or tasks incur in high energy costs that hinder their… (more)

Subjects/Keywords: localization; mobile robotics; sensor fusion; state estimation; statistical inference; wireless sensor networks; Aerospace Engineering; Robotics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Iglesias Echevarria, D. I. (2017). Cooperative Robot Localization Using Event-Triggered Estimation. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/185

Chicago Manual of Style (16^th Edition):

Iglesias Echevarria, David I. “Cooperative Robot Localization Using Event-Triggered Estimation.” 2017. Masters Thesis, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/185.

MLA Handbook (7^th Edition):

Iglesias Echevarria, David I. “Cooperative Robot Localization Using Event-Triggered Estimation.” 2017. Web. 12 Nov 2019.

Vancouver:

Iglesias Echevarria DI. Cooperative Robot Localization Using Event-Triggered Estimation. [Internet] [Masters thesis]. University of Colorado; 2017. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/185.

Council of Science Editors:

Iglesias Echevarria DI. Cooperative Robot Localization Using Event-Triggered Estimation. [Masters Thesis]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/asen_gradetds/185

University of Colorado

2. Iglesias Echevarria, David I. Cooperative Robot Localization Using Event-Triggered Estimation.

Degree: MS, 2017, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/206

► It is known that multiple robot systems that need to cooperate to perform certain activities or tasks incur in high energy costs that hinder their… (more)

Subjects/Keywords: localization; mobile robotics; sensor fusion; state estimation; statistical inference; wireless sensor networks; Aerospace Engineering; Robotics

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Iglesias Echevarria, D. I. (2017). Cooperative Robot Localization Using Event-Triggered Estimation. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/206

Chicago Manual of Style (16^th Edition):

Iglesias Echevarria, David I. “Cooperative Robot Localization Using Event-Triggered Estimation.” 2017. Masters Thesis, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/206.

MLA Handbook (7^th Edition):

Iglesias Echevarria, David I. “Cooperative Robot Localization Using Event-Triggered Estimation.” 2017. Web. 12 Nov 2019.

Vancouver:

Iglesias Echevarria DI. Cooperative Robot Localization Using Event-Triggered Estimation. [Internet] [Masters thesis]. University of Colorado; 2017. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/206.

Council of Science Editors:

Iglesias Echevarria DI. Cooperative Robot Localization Using Event-Triggered Estimation. [Masters Thesis]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/asen_gradetds/206

University of Colorado

3. Dietrich, Ann Brown. Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies.

Degree: PhD, Aerospace Engineering Sciences, 2017, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/178

► Spacecraft navigation in proximity to small celestial bodies, such as asteroids and comets, is challenging due to their complex dynamical environment and the lag in… (more)

▼ Spacecraft navigation in proximity to small celestial bodies, such as asteroids and comets, is challenging due to their complex dynamical environment and the lag in communications from Earth to the spacecraft. Increasing autonomous spacecraft navigation reduces the burden of ground-based planning and modeling, and enables insightful mission profiles. The state-of-the-art of relative spacecraft navigation uses optical images, requires an iterative procedure, and currently must be performed on the ground. A flash lidar instrument instantaneously returns a 3D elevation map of its target and shows promise for advancing autonomous spacecraft navigation. Using this instrument as a relative measurement source for navigation performed similarly or better than landmark-based navigation from optical images. The model-based approach used to compute the onboard flash lidar images eliminated the correlation procedures required of landmark-based approaches, and reduced the computational load. An extended Kalman filter (EKF), an unscented Kalman filter (UKF), and an iterative least-squares (LS) filter were investigated in this analysis. The iterative LS filter iterated the estimation state at each observation time, produced smaller errors than the EKF and UKF, and did not encounter filter saturation. The image properties of the flash lidar measurements allowed for pointing to be estimated. The UKF and LS filters were robust to initial position errors as long as an overlap occurred between the observed and computed flash lidar images. When introducing shape modeling errors, the filters did not diverge, and the majority of the state errors were captured with a sequential consider covariance analysis. Using the image properties of the flash lidar images, and assuming inertial spacecraft pointing knowledge, the filter was initialized through pre-processing algorithms and the iterative LS algorithm. Optimally reducing the number of altimetry measurements processed by maximizing their information contribution increased the computational efficiency and combated filter saturation without sacrificing accuracy. Advisors/Committee Members: Jay W. McMahon, Dan Scheeres, Hanspeter Schaub, Eric Frew, Behrouz Touri.

Subjects/Keywords: Lidar; orbit determination; Small bodies; Aerospace Engineering; Astrodynamics; Navigation, Guidance, Control and Dynamics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Dietrich, A. B. (2017). Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/178

Chicago Manual of Style (16^th Edition):

Dietrich, Ann Brown. “Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies.” 2017. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/178.

MLA Handbook (7^th Edition):

Dietrich, Ann Brown. “Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies.” 2017. Web. 12 Nov 2019.

Vancouver:

Dietrich AB. Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/178.

Council of Science Editors:

Dietrich AB. Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/asen_gradetds/178

University of Colorado

4. Geeraert, Jeroen L. Multi-Satellite Orbit Determination Using Interferometric Observables with RF Localization Applications.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/192

► Very long baseline interferometry (VLBI) specifically same-beam interferometry (SBI), and dual-satellite geolocation are two fields of research not previously connected. This is due to… (more)

▼ Very long baseline interferometry (VLBI) specifically same-beam interferometry (SBI), and dual-satellite geolocation are two fields of research not previously connected. This is due to the different application of each field, SBI is used for relative interplanetary navigation of two satellites while dual-satellite geolocation is used to locate the source of a radio frequency (RF) signal. In this dissertation however, we leverage both fields to create a novel method for multi-satellite orbit determination (OD) using time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements. The measurements are double differenced between the satellites and the stations, in so doing, many of the common errors are canceled which can significantly improve measurement precision. Provided with this novel OD technique, the observability is first analyzed to determine the benefits and limitations of this method. In all but a few scenarios the measurements successfully reduce the covariance when examining the Cramér-Rao Lower Bound (CRLB). Reduced observability is encountered with geostationary satellites as their motion with respect to the stations is limited, especially when only one baseline is used. However, when using satellite pairs with greater relative motion with respect to the stations, even satellites that are close to, but not exactly in a geostationary orbit can be estimated accurately. We find that in a strong majority of cases the OD technique provides lower uncertainties and solutions far more accurate than using conventional OD observables such as range and range-rate while also not being affected by common errors and biases. We specifically examine GEO-GEO, GEO-MEO, and GEO-LEO dual-satellite estimation cases. The work is further extended by developing a relative navigation scenario where the chief satellite is assumed to have perfect knowledge, or some small amount of uncertainty considered but not estimated, while estimating the deputy satellite state with respect to the chief. Once again the results demonstrate that the TDOA and FDOA OD results are favorable with faster dynamics over classical measurements. This dissertation not only explores the OD side, but also gaps in geolocation research. First the mapping of ephemeris uncertainty to the geolocation covariance to provide a more realistic covariance was implemented. Furthermore, the geolocation solution was improved by appending a probabilistic altitude constraint to the posterior covariance, significantly reducing the projected geolocation uncertainty ellipse. The feasibility of using the geolocation setup to passively locate a LEO satellite was also considered. Finally the simulated results were verified using a long-arc of real data. The use of FDOA for small-body navigation and gravity recovery was also examined as an extended application. Advisors/Committee Members: Jay W. McMahon, Penina Axelrad, Brandon Jones, Daniel Scheeres, Behrouz Touri.

Subjects/Keywords: astrodynamics; geolocation; interferometry; orbit determination; Aerospace Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Geeraert, J. L. (2017). Multi-Satellite Orbit Determination Using Interferometric Observables with RF Localization Applications. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/192

Chicago Manual of Style (16^th Edition):

Geeraert, Jeroen L. “Multi-Satellite Orbit Determination Using Interferometric Observables with RF Localization Applications.” 2017. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/192.

MLA Handbook (7^th Edition):

Geeraert, Jeroen L. “Multi-Satellite Orbit Determination Using Interferometric Observables with RF Localization Applications.” 2017. Web. 12 Nov 2019.

Vancouver:

Geeraert JL. Multi-Satellite Orbit Determination Using Interferometric Observables with RF Localization Applications. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/192.

Council of Science Editors:

Geeraert JL. Multi-Satellite Orbit Determination Using Interferometric Observables with RF Localization Applications. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/asen_gradetds/192

University of Colorado

5. Dietrich, Ann Brown. Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/215

► Spacecraft navigation in proximity to small celestial bodies, such as asteroids and comets, is challenging due to their complex dynamical environment and the lag in… (more)

▼ Spacecraft navigation in proximity to small celestial bodies, such as asteroids and comets, is challenging due to their complex dynamical environment and the lag in communications from Earth to the spacecraft. Increasing autonomous spacecraft navigation reduces the burden of ground-based planning and modeling, and enables insightful mission profiles. The state-of-the-art of relative spacecraft navigation uses optical images, requires an iterative procedure, and currently must be performed on the ground. A flash lidar instrument instantaneously returns a 3D elevation map of its target and shows promise for advancing autonomous spacecraft navigation. Using this instrument as a relative measurement source for navigation performed similarly or better than landmark-based navigation from optical images. The model-based approach used to compute the onboard flash lidar images eliminated the correlation procedures required of landmark-based approaches, and reduced the computational load. An extended Kalman filter (EKF), an unscented Kalman filter (UKF), and an iterative least-squares (LS) filter were investigated in this analysis. The iterative LS filter iterated the estimation state at each observation time, produced smaller errors than the EKF and UKF, and did not encounter filter saturation. The image properties of the flash lidar measurements allowed for pointing to be estimated. The UKF and LS filters were robust to initial position errors as long as an overlap occurred between the observed and computed flash lidar images. When introducing shape modeling errors, the filters did not diverge, and the majority of the state errors were captured with a sequential consider covariance analysis. Using the image properties of the flash lidar images, and assuming inertial spacecraft pointing knowledge, the filter was initialized through pre-processing algorithms and the iterative LS algorithm. Optimally reducing the number of altimetry measurements processed by maximizing their information contribution increased the computational efficiency and combated filter saturation without sacrificing accuracy. Advisors/Committee Members: Jay W. McMahon, Dan Scheeres, Hanspeter Schaub, Eric Frew, Behrouz Touri.

Subjects/Keywords: lidar; orbit determination; small bodies; autonomous navigation; least-squares filter; Aerospace Engineering; Theory and Algorithms

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Dietrich, A. B. (2017). Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/215

Chicago Manual of Style (16^th Edition):

Dietrich, Ann Brown. “Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies.” 2017. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/215.

MLA Handbook (7^th Edition):

Dietrich, Ann Brown. “Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies.” 2017. Web. 12 Nov 2019.

Vancouver:

Dietrich AB. Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/215.

Council of Science Editors:

Dietrich AB. Supporting Autonomous Navigation with Flash Lidar Images in Proximity to Small Celestial Bodies. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/asen_gradetds/215

University of Colorado

6. Rosengren, Aaron Jay. Long-term Dynamical Behavior of Highly Perturbed Natural and Artificial Celestial Bodies.

Degree: PhD, Aerospace Engineering Sciences, 2014, University of Colorado

URL: http://scholar.colorado.edu/asen_gradetds/79

► This thesis explores the dynamical evolution of celestial bodies, both natural and artificial, which are strongly perturbed by solar radiation pressure—a non-gravitational force that… (more)

▼ This thesis explores the dynamical evolution of celestial bodies, both natural and artificial, which are strongly perturbed by solar radiation pressure—a non-gravitational force that has played an increasingly important role in celestial mechanics since the early 1900s. The particular focus is on the high area-to-mass ratio (HAMR) space debris discovered in near geosynchronous Earth orbit (GEO) through optical observations in 2004, and on micron-sized circumplanetary dust particles in the outer Saturnian system. The formalism developed can also be applied to—and, indeed, was unquestionably influenced by—the orbital motion of spacecraft about small bodies (asteroids and comets). The chief difficulties which arise in getting an accurate understanding of the motion of such bodies in highly perturbed dynamical environments come, in part, from the nonlinearity of the dynamical system, but more so from the inadequacy of the classical approaches and methods. While modern formulations based on numerical integrations can give “precise” solutions for specific initial conditions, these afford little insight into the nature of the problem or the essential dependence of the perturbed motion on the system parameters. The predominant perturbations acting on HAMR objects and circumplanetary dust grains are solar radiation pressure, planetary oblateness, and third-body gravitational interactions induced by the Sun and nearby natural satellites. We developed first-order averaged models, based on the Milankovitch formulation of perturbation theory, which govern the long-term evolution of orbits subject to these perturbing forces. The unexpectedly rich results obtained by the use of this vector formalism are due to certain important circumstances in celestial and quantum mechanics which gave rise to its origin and development. An attempt has been made to trace these historical developments and to put them into the perspective of the present. The averaged equations of motion hold rigorously for all Keplerian orbits with nonzero angular momentum; they are free of the mathematical singularities associated with circular or equatorial orbits. These approximate equations are written in a concise analytical vector form, which allow our results and demonstrations to attain such extraordinary simplicity and clarity. As a first attempt to understand the disturbed motion, we consider separately the first-order effects of each principal perturbation in altering the orbital elements. We establish that each of these problems is integrable (under certain well-justified assumptions), and that they admit either an exact analytical solution or a complete qualitative description. We then explore the complex interplay between gravitational and non-gravitational perturbations, and examine stable “frozen” orbit configurations and resonances which can occur when these forces act in concert. These results are applied to the study of the dynamics and stability of GEO orbits and to the identification of robust, long-term disposal orbits… Advisors/Committee Members: Daniel J. Scheeres, Philip J. Armitage, Moriba K. Jah, Jay W. McMahon, Hanspeter Schaub.

Subjects/Keywords: Astrodynamics; Celestial Mechanics; Classical Mechanics; Planetary Science; Space Debris; Space Situational Awareness; Astrophysics and Astronomy; Physical Processes; The Sun and the Solar System

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Rosengren, A. J. (2014). Long-term Dynamical Behavior of Highly Perturbed Natural and Artificial Celestial Bodies. (Doctoral Dissertation). University of Colorado. Retrieved from http://scholar.colorado.edu/asen_gradetds/79

Chicago Manual of Style (16^th Edition):

Rosengren, Aaron Jay. “Long-term Dynamical Behavior of Highly Perturbed Natural and Artificial Celestial Bodies.” 2014. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. http://scholar.colorado.edu/asen_gradetds/79.

MLA Handbook (7^th Edition):

Rosengren, Aaron Jay. “Long-term Dynamical Behavior of Highly Perturbed Natural and Artificial Celestial Bodies.” 2014. Web. 12 Nov 2019.

Vancouver:

Rosengren AJ. Long-term Dynamical Behavior of Highly Perturbed Natural and Artificial Celestial Bodies. [Internet] [Doctoral dissertation]. University of Colorado; 2014. [cited 2019 Nov 12]. Available from: http://scholar.colorado.edu/asen_gradetds/79.

Council of Science Editors:

Rosengren AJ. Long-term Dynamical Behavior of Highly Perturbed Natural and Artificial Celestial Bodies. [Doctoral Dissertation]. University of Colorado; 2014. Available from: http://scholar.colorado.edu/asen_gradetds/79

University of Colorado

7. Guerrant, Daniel Vernon. Performance Quantification of Heliogyro Solar Sails Using Structural, Attitude, and Orbital Dynamics and Control Analysis.

Degree: PhD, Aerospace Engineering Sciences, 2015, University of Colorado

URL: http://scholar.colorado.edu/asen_gradetds/101

► Solar sails enable or enhance exploration of a variety of destinations both within and without the solar system. The heliogyro solar sail architecture divides… (more)

Subjects/Keywords: attitude control; dynamics; heliogyro; solar sail; structural dynamics; Astrodynamics; Propulsion and Power; Space Vehicles

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APA (6^th Edition):

Guerrant, D. V. (2015). Performance Quantification of Heliogyro Solar Sails Using Structural, Attitude, and Orbital Dynamics and Control Analysis. (Doctoral Dissertation). University of Colorado. Retrieved from http://scholar.colorado.edu/asen_gradetds/101

Chicago Manual of Style (16^th Edition):

Guerrant, Daniel Vernon. “Performance Quantification of Heliogyro Solar Sails Using Structural, Attitude, and Orbital Dynamics and Control Analysis.” 2015. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. http://scholar.colorado.edu/asen_gradetds/101.

MLA Handbook (7^th Edition):

Guerrant, Daniel Vernon. “Performance Quantification of Heliogyro Solar Sails Using Structural, Attitude, and Orbital Dynamics and Control Analysis.” 2015. Web. 12 Nov 2019.

Vancouver:

Guerrant DV. Performance Quantification of Heliogyro Solar Sails Using Structural, Attitude, and Orbital Dynamics and Control Analysis. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2019 Nov 12]. Available from: http://scholar.colorado.edu/asen_gradetds/101.

Council of Science Editors:

Guerrant DV. Performance Quantification of Heliogyro Solar Sails Using Structural, Attitude, and Orbital Dynamics and Control Analysis. [Doctoral Dissertation]. University of Colorado; 2015. Available from: http://scholar.colorado.edu/asen_gradetds/101

University of Colorado

8. Ko, Hyun Chul. Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications.

Degree: PhD, Aerospace Engineering Sciences, 2015, University of Colorado

URL: http://scholar.colorado.edu/asen_gradetds/120

► A new way of representing unknown and unmodeled space events (USEs) with Thrust-Fourier-Coefficients (TFCs) is introduced and its applications to satellite orbit determination (OD)… (more)

▼ A new way of representing unknown and unmodeled space events (USEs) with Thrust-Fourier-Coefficients (TFCs) is introduced and its applications to satellite orbit determination (OD) and event detection are studied. A USE is regarded as an event due to unknown changes of force model caused by unplanned maneuvers, unknown deployment, collision, or some other drastic change in space environment. A satellite's motion under USEs, transitioning between two arbitrary orbit states, can be represented as an equivalent orbital maneuver connecting those two states by applying the Fourier series representation of perturbing accelerations. This event representation with TFCs rigorously provides a unique control law that can generate the given secular behavior of a satellite due to a USE. This technique enables us to facilitate the analytical propagation of orbit information across a USE, which allows for the usage of an existing pre-event orbit solution to compute a post-event orbit solution. By directly appending TFCs and the represented event dynamics to a regular OD filter, the modified filter using TFCs is able to blend post-event tracking data to improve a post-event orbit solution in the absence of a dynamics model of USE. Case studies with simulated tracking data show that the event representation using TFCs helps to maintain OD across a period of USEs. In addition, when there is measurement data available during USEs, a modified sequential filter with TFCs is able to detect the onset and the termination time of an event. This event representation-based OD and event detection distinguishes itself from other approaches in that it does not rely on any assumption or a priori information of a USE. This generic approach enables us to fit tracking data in real time and therefore to maintain a satellite tracking in the presence of USEs. This method has the advantage of avoiding the difficulty of manual parameter tuning and, thus, is able to provide more accurate post-event OD solution with a single OD filter. Advisors/Committee Members: Daniel J. Scheeres, George H. Born, John Hauser, Jay W. McMahon, Jeffrey S. Parker.

Subjects/Keywords: Event Detection; Event Representation; Maneuvering Satellite Tracking; Orbit Determination; Thrust-Fourier-Coefficients; Unknown Space Event; Mechanical Engineering; Navigation, Guidance, Control and Dynamics; Space Vehicles; Systems Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ko, H. C. (2015). Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications. (Doctoral Dissertation). University of Colorado. Retrieved from http://scholar.colorado.edu/asen_gradetds/120

Chicago Manual of Style (16^th Edition):

Ko, Hyun Chul. “Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications.” 2015. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. http://scholar.colorado.edu/asen_gradetds/120.

MLA Handbook (7^th Edition):

Ko, Hyun Chul. “Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications.” 2015. Web. 12 Nov 2019.

Vancouver:

Ko HC. Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2019 Nov 12]. Available from: http://scholar.colorado.edu/asen_gradetds/120.

Council of Science Editors:

Ko HC. Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications. [Doctoral Dissertation]. University of Colorado; 2015. Available from: http://scholar.colorado.edu/asen_gradetds/120

University of Colorado

9. Hesar, Siamak Ghanizadeh. A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft.

Degree: PhD, Aerospace Engineering Sciences, 2016, University of Colorado

URL: http://scholar.colorado.edu/asen_gradetds/141

► Spacecraft flying in close proximity of small bodies face a very complex dynamical environment with numerous types of perturbing forces acting on them. Development… (more)

▼ Spacecraft flying in close proximity of small bodies face a very complex dynamical environment with numerous types of perturbing forces acting on them. Development of new techniques are needed for precise navigation of spacecraft in such environments. This study focuses on furthering our understanding of precise orbit determination of spacecraft in close proximity of small bodies via implementation of new methods for precise representation of strong and weak perturbing forces acting on spacecraft, such as the irregular gravitational field, strong solar radiation pressure effects, and thermal radiation pressure effects from the surface of small bodies. Solar radiation pressure is a strong perturbing force acting on spacecraft in the orbital environment of small bodies that constantly pushes the spacecraft in a general direction away from the Sun. The existence of strong solar radiation pressure effects creates a complex dynamical environment around asteroids and comets that results in a particular set of orbital regimes, such as the family of the terminator or close to terminator orbits, whose dynamical evolution may not be intuitive. Small perturbations caused by maneuver errors and other sources may lead to large deviations in a spacecraft trajectory from its nominal orbit. Understanding the evolution of errors and uncertainties in the orbital elements of spacecraft is a crucial piece of mission planning and spacecraft navigation. In this thesis, we derive analytical expressions that govern the secular motion of the perturbed orbital elements in an environment that is strongly perturbed by the solar radiation pressure effects. Furthermore, we study a framework based on a Fourier series expansion for precise representation of the solar radiation pressure and small body surface thermal radiation pressure effects on spacecraft. This method is utilized in generating precise orbit determination solutions for simulated spacecraft in orbit about small bodies in the presence of dynamical and modeling errors. Gravitational perturbations are other major disturbing forces in the proximity of a small body. This is especially true for spacecraft that come close to the surface of asteroids or comets in a landing or touch-and-go (TAG) scenario. Due to the irregular shape of these objects, a significant portion of the landing or TAG trajectory may lie inside a circumscribing sphere, where the conventional spherical harmonics expansion of the gravitational field is not convergent. Recent studies developed a so-called "interior" gravity field spherical harmonics expansion that extends down to the surface of the object without divergence issues. The interior gravity field, however, is not studied in the context of orbit determination and spacecraft navigation. This study investigates the feasibility of the utilization of such model to navigate spacecraft in a trajectory that is close to the surface of an irregularly shaped body of mass. The study will further examine the capability of estimating the spherical… Advisors/Committee Members: Daniel J. Scheeres, Jeffrey S. Parker, Jay W. McMahon, Webster Cash, Shyam Bhaskaran.

Subjects/Keywords: Interior Gravity Field; Precise Orbit Determination; Small Body Navigation; Solar Radiation Pressure; Spacecraft Navigation; Thermal Radiation Pressure; Aerospace Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Hesar, S. G. (2016). A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft. (Doctoral Dissertation). University of Colorado. Retrieved from http://scholar.colorado.edu/asen_gradetds/141

Chicago Manual of Style (16^th Edition):

Hesar, Siamak Ghanizadeh. “A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft.” 2016. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. http://scholar.colorado.edu/asen_gradetds/141.

MLA Handbook (7^th Edition):

Hesar, Siamak Ghanizadeh. “A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft.” 2016. Web. 12 Nov 2019.

Vancouver:

Hesar SG. A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft. [Internet] [Doctoral dissertation]. University of Colorado; 2016. [cited 2019 Nov 12]. Available from: http://scholar.colorado.edu/asen_gradetds/141.

Council of Science Editors:

Hesar SG. A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft. [Doctoral Dissertation]. University of Colorado; 2016. Available from: http://scholar.colorado.edu/asen_gradetds/141

University of Colorado

10. Baresi, Nicola. Spacecraft Formation Flight on Quasi-Periodic Invariant Tori.

Degree: PhD, Aerospace Engineering Sciences, 2017, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/176

► Since the successful rendezvous of the Gemini VI and VII spacecraft in 1965, spacecraft formation flying has attracted the interest of many researchers in… (more)

▼ Since the successful rendezvous of the Gemini VI and VII spacecraft in 1965, spacecraft formation flying has attracted the interest of many researchers in the field. Yet, existing methodologies do not currently account for the oblateness of a central body when the distance between the satellites exceeds the reach of standard analytical techniques such as Brouwer-Lyddane theory and thereof. In this dissertation, the problem of designing bounded relative orbits is approached with a dynamical systems theory perspective in order to overcome the limitations imposed by mean-to-osculating orbit element mappings and linearization errors. We find that the dynamics of satellites in the Earth zonal problem can be fundamentally described by three periods, whose averaged values can be accurately computed through numerical integration. To ensure long-term bounded relative motion between the satellites in a formation, at least two of their fundamental periods need to be matched on average. This condition is enforced by including additional constraints into existing techniques for calculating families of quasi-periodic invariant tori. The result is a numerical procedure that searches for the invariant curves of a stroboscopic mapping while changing the polar component of the angular momentum vector for each of the quasi-periodic tori within the family. Upon convergence, the algorithm outputs several curves that can be interpolated to obtain an entire surface of bounded relative motion. That is, by selecting arbitrary initial conditions on this surface, bounded relative motion can be established, regardless of the number of zonal harmonics terms that are included in the geopotential. Given this encouraging result, we move beyond Earth's orbit and investigate the problem of designing bounded relative orbits about small irregular bodies. First, we consider the case of asteroid (4179) Toutatis, and build on previous research to identify periodic and quasi-periodic orbits that ensure boundedness in spite of the complex shape and rotational state of the target asteroid. Next, we move to the Martian system and design spacecraft formations near Phobos. Once again, we aim at improving the realism of previous simulations found in the literature by modeling the nonspherical shape and nonzero eccentricity of the Martian moon. The resulting higher fidelity model causes entire families of periodic orbits to become quasi-periodic invariant tori that eventually serve as initial conditions for bounded spacecraft formations. The last part of this thesis is dedicated to assessing the robustness of the relative trajectories computed throughout the manuscript. Although atmospheric drag and solar radiation pressure have catastrophic effects on the relative dynamics of satellites in LEO and near Toutatis, it is found that spacecraft formations in MEO, GEO, and about Phobos are quite resilient to mismodeled dynamics, making quasi-periodic invariant tori a robust option for flying satellite clusters in these complex dynamical… Advisors/Committee Members: Daniel J. Scheeres, Natasha Bosanac, Jay W. McMahon, James D. Miss, Hanspeter Schaub.

Subjects/Keywords: Astrodynamics; Cluster Flight; Dynamical Systems Theory; Quasi-periodic Invariant Tori; Spacecraft Formation Flying; Aerospace Engineering; Space Vehicles

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APA (6^th Edition):

Baresi, N. (2017). Spacecraft Formation Flight on Quasi-Periodic Invariant Tori. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/176

Chicago Manual of Style (16^th Edition):

Baresi, Nicola. “Spacecraft Formation Flight on Quasi-Periodic Invariant Tori.” 2017. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/176.

MLA Handbook (7^th Edition):

Baresi, Nicola. “Spacecraft Formation Flight on Quasi-Periodic Invariant Tori.” 2017. Web. 12 Nov 2019.

Vancouver:

Baresi N. Spacecraft Formation Flight on Quasi-Periodic Invariant Tori. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/176.

Council of Science Editors:

Baresi N. Spacecraft Formation Flight on Quasi-Periodic Invariant Tori. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/asen_gradetds/176

University of Colorado

11. Aziz, Jonathan David. Low-Thrust Many-Revolution Trajectory Optimization.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/210

► This dissertation presents a method for optimizing the trajectories of spacecraft that use low-thrust propulsion to maneuver through high counts of orbital revolutions. The… (more)

▼ This dissertation presents a method for optimizing the trajectories of spacecraft that use low-thrust propulsion to maneuver through high counts of orbital revolutions. The proposed method is to discretize the trajectory and control schedule with respect to an orbit anomaly and perform the optimization with differential dynamic programming (DDP). The change of variable from time to orbit anomaly is accomplished by a Sundman transformation to the spacecraft equations of motion. Sundman transformations to each of the true, mean and eccentric anomalies are leveraged for fuel-optimal geocentric transfers up to 2000 revolutions. The approach is shown to be amenable to the inclusion of perturbations in the dynamic model, specifically aspherical gravity and third-body perturbations, and is improved upon through the use of modified equinoctial elements. An assessment of computational performance shows the importance of parallelization but that a single, multi-core processor is effective. The computational efficiency facilitates the generation of fuel versus time of flight trade-offs within a matter of hours. Many-revolution trajectories are characteristic of orbit transfers accomplished by solar electric propulsion about planetary bodies. Methods for modeling the effect of solar eclipses on the power available to the spacecraft and constraining eclipse durations are also presented. The logistic sunlight fraction is introduced as a coefficient that scales the computed power available by the fraction of sunlight available. The logistic sunlight fraction and Sundman-transformed DDP are used to analyze transfers from low-Earth orbit to geostationary orbit. The analysis includes a systematic approach to estimating the Pareto front of fuel versus time of flight. In addition to addressing many-revolution trajectories, this dissertation advances the utility of DDP in the three-body problem. Fuel-optimal transfers are presented in the Earth-Moon circular restricted three-body problem between distant retrograde orbits, between Lyapunov orbits and between Halo orbits. Those include mechanisms for varying the time of flight and the insertion point onto a target orbit. A multi-phase DDP approach enables initial guesses to be constructed from discontinuous trajectory segments. DDP is shown to leverage the system dynamics to find a heteroclinic connection between Lyapunov orbits, which is facilitated by the multi-phase approach. Advisors/Committee Members: Daniel J. Scheeres, Shalom D. Ruben, Jeffrey S. Parker, Jacob A. Englander, Jay W. McMahon.

Subjects/Keywords: differential dynamic programming; low-thrust propulsion; solar electric propulsion; spaceflight; sundman transformation; trajectory optimization; Aerospace Engineering; Models and Methods

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Aziz, J. D. (2018). Low-Thrust Many-Revolution Trajectory Optimization. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/210

Chicago Manual of Style (16^th Edition):

Aziz, Jonathan David. “Low-Thrust Many-Revolution Trajectory Optimization.” 2018. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/210.

MLA Handbook (7^th Edition):

Aziz, Jonathan David. “Low-Thrust Many-Revolution Trajectory Optimization.” 2018. Web. 12 Nov 2019.

Vancouver:

Aziz JD. Low-Thrust Many-Revolution Trajectory Optimization. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/210.

Council of Science Editors:

Aziz JD. Low-Thrust Many-Revolution Trajectory Optimization. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/asen_gradetds/210

University of Colorado

12. Parrish, Nathan Luis Olin. Low Thrust Trajectory Optimization in Cislunar and Translunar Space.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/202

► Low-thrust propulsion technologies such as electric propulsion and solar sails are key to enabling many space missions which would be impractical with chemical propulsion.… (more)

▼ Low-thrust propulsion technologies such as electric propulsion and solar sails are key to enabling many space missions which would be impractical with chemical propulsion. With exhaust velocities 10x higher than chemical rockets, electric propulsion systems can deliver a spacecraft to its target state for a fraction of the fuel. Due to the low thrust, the control must remain active for weeks or even years. When three-body dynamics are considered, the change in dynamics over the course of a trajectory can be extreme. This greatly complicates low-thrust mission design and navigation in cislunar and translunar space, making it an area of active research. Deterministic strategies for trajectory design and optimization rely on linearizing the problem and solving a series of linearized problems. In regimes with simple or slowly-varying dynamics, the linearization holds “true enough”, and we can easily arrive at a solution. However, three-body environments readily provide real cases where the linearization for all but the most carefully-chosen problem descriptions break down. This thesis presents a few modifications to existing algorithms to improve convergence. This thesis then uses this fast, robust method for trajectory optimization to generate training samples for a machine learning approach to optimal trajectory correction. We begin with one optimal low-thrust transfer. Then, we optimize thousands of transfers in the neighborhood of the nominal transfer. These transfers are described in the language of indirect optimal control, with the optimal control given as a function of Lawden’s primer vector. We see that for a slightly different initial condition, the states and the costates both follow a slightly different trajectory to the target. A feedforward artificial neural network is trained to map the difference in states to the difference in costates, with a high degree of accuracy. Finally, we explore a potential application of this neural network: spacecraft that can navigate themselves autonomously in the presence of errors. We propose this as a method for future spacecraft that can optimally correct their trajectories without ground contacts. We demonstrate neural network navigation in two simplified dynamical environments: two-body heliocentric gravity, and the Earth-Moon circular restricted three body problem. Advisors/Committee Members: Daniel J. Scheeres, Jeffrey S. Parker, Jay W. McMahon, Christoffer Heckman, Daniel Kubitschek.

Subjects/Keywords: artificial intelligence; crtbp; electric propulsion; neural networks; optimization; Aerospace Engineering; Engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Parrish, N. L. O. (2018). Low Thrust Trajectory Optimization in Cislunar and Translunar Space. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/202

Chicago Manual of Style (16^th Edition):

Parrish, Nathan Luis Olin. “Low Thrust Trajectory Optimization in Cislunar and Translunar Space.” 2018. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/202.

MLA Handbook (7^th Edition):

Parrish, Nathan Luis Olin. “Low Thrust Trajectory Optimization in Cislunar and Translunar Space.” 2018. Web. 12 Nov 2019.

Vancouver:

Parrish NLO. Low Thrust Trajectory Optimization in Cislunar and Translunar Space. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/202.

Council of Science Editors:

Parrish NLO. Low Thrust Trajectory Optimization in Cislunar and Translunar Space. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/asen_gradetds/202

University of Colorado

13. Baresi, Nicola. Spacecraft Formation Flight on Quasi-Periodic Invariant Tori.

Degree: PhD, 2017, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/219

► Since the successful rendezvous of the Gemini VI and VII spacecraft in 1965, spacecraft formation flying has attracted the interest of many researchers in… (more)

▼ Since the successful rendezvous of the Gemini VI and VII spacecraft in 1965, spacecraft formation flying has attracted the interest of many researchers in the field. Yet, existing methodologies do not currently account for the oblateness of a central body when the distance between the satellites exceeds the reach of standard analytical techniques such as Brouwer-Lyddane theory and thereof. In this dissertation, the problem of designing bounded relative orbits is approached with a dynamical systems theory perspective in order to overcome the limitations imposed by mean-to-osculating orbit element mappings and linearization errors. We find that the dynamics of satellites in the Earth zonal problem can be fundamentally described by three periods, whose averaged values can be accurately computed through numerical integration. To ensure long-term bounded relative motion between the satellites in a formation, at least two of their fundamental periods need to be matched on average. This condition is enforced by including additional constraints into existing techniques for calculating families of quasi-periodic invariant tori. The result is a numerical procedure that searches for the invariant curves of a stroboscopic mapping while changing the polar component of the angular momentum vector for each of the quasi-periodic tori within the family. Upon convergence, the algorithm outputs several curves that can be interpolated to obtain an entire surface of bounded relative motion. That is, by selecting arbitrary initial conditions on this surface, bounded relative motion can be established, regardless of the number of zonal harmonics terms that are included in the geopotential. Given this encouraging result, we move beyond Earth's orbit and investigate the problem of designing bounded relative orbits about small irregular bodies. First, we consider the case of asteroid (4179) Toutatis, and build on previous research to identify periodic and quasi-periodic orbits that ensure boundedness in spite of the complex shape and rotational state of the target asteroid. Next, we move to the Martian system and design spacecraft formations near Phobos. Once again, we aim at improving the realism of previous simulations found in the literature by modeling the nonspherical shape and nonzero eccentricity of the Martian moon. The resulting higher fidelity model causes entire families of periodic orbits to become quasi-periodic invariant tori that eventually serve as initial conditions for bounded spacecraft formations. The last part of this thesis is dedicated to assessing the robustness of the relative trajectories computed throughout the manuscript. Although atmospheric drag and solar radiation pressure have catastrophic effects on the relative dynamics of satellites in LEO and near Toutatis, it is found that spacecraft formations in MEO, GEO, and about Phobos are quite resilient to mismodeled dynamics, making quasi-periodic invariant tori a robust option for flying satellite clusters in these complex dynamical… Advisors/Committee Members: Daniel J. Scheeres, Natasha Bosanac, Jay W. McMahon, James D. Miss, Hanspeter Schaub.

Subjects/Keywords: astrodynamics; cluster flight; dynamical systems theory; quasi-periodic invariant tori; spacecraft formation flying; Aerospace Engineering; Astrodynamics

Record Details Similar Records Cite « Share

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Baresi, N. (2017). Spacecraft Formation Flight on Quasi-Periodic Invariant Tori. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/219

Chicago Manual of Style (16^th Edition):

Baresi, Nicola. “Spacecraft Formation Flight on Quasi-Periodic Invariant Tori.” 2017. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/219.

MLA Handbook (7^th Edition):

Baresi, Nicola. “Spacecraft Formation Flight on Quasi-Periodic Invariant Tori.” 2017. Web. 12 Nov 2019.

Vancouver:

Baresi N. Spacecraft Formation Flight on Quasi-Periodic Invariant Tori. [Internet] [Doctoral dissertation]. University of Colorado; 2017. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/219.

Council of Science Editors:

Baresi N. Spacecraft Formation Flight on Quasi-Periodic Invariant Tori. [Doctoral Dissertation]. University of Colorado; 2017. Available from: https://scholar.colorado.edu/asen_gradetds/219

University of Colorado

14. Croteau, Michael Joseph. Daily GRACE Water Storage Estimates for Improving Hydrology Models and Forecasting.

Degree: PhD, Aerospace Engineering Sciences, 2019, University of Colorado

URL: https://scholar.colorado.edu/asen_gradetds/255

► The Gravity Recovery and Climate Experiment (GRACE) has created a more than 15 year record of time variable gravity and enabled studies of regional terrestrial… (more)

Subjects/Keywords: grace; hydrology; mascons; terrestrial water storage; gravity recovery and climate experiment; Aerospace Engineering; Hydrology

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Croteau, M. J. (2019). Daily GRACE Water Storage Estimates for Improving Hydrology Models and Forecasting. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/255

Chicago Manual of Style (16^th Edition):

Croteau, Michael Joseph. “Daily GRACE Water Storage Estimates for Improving Hydrology Models and Forecasting.” 2019. Doctoral Dissertation, University of Colorado. Accessed November 12, 2019. https://scholar.colorado.edu/asen_gradetds/255.

MLA Handbook (7^th Edition):

Croteau, Michael Joseph. “Daily GRACE Water Storage Estimates for Improving Hydrology Models and Forecasting.” 2019. Web. 12 Nov 2019.

Vancouver:

Croteau MJ. Daily GRACE Water Storage Estimates for Improving Hydrology Models and Forecasting. [Internet] [Doctoral dissertation]. University of Colorado; 2019. [cited 2019 Nov 12]. Available from: https://scholar.colorado.edu/asen_gradetds/255.

Council of Science Editors:

Croteau MJ. Daily GRACE Water Storage Estimates for Improving Hydrology Models and Forecasting. [Doctoral Dissertation]. University of Colorado; 2019. Available from: https://scholar.colorado.edu/asen_gradetds/255

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