+publisher:"Texas A&M University" +contributor:("Junkins, John")

Texas A&M University

1. Roshan Suresh Kumar, FNU. Calibration of Linear Imager Camera for Relative Pose Estimation.

Degree: MS, Aerospace Engineering, 2019, Texas A&M University

URL: http://hdl.handle.net/1969.1/187541

► The process of camera calibration is of paramount importance in order to employ any vision based sensor for relative navigation purposes. Understanding and quantifying the… (more)

Subjects/Keywords: Camera Calibration; Linear Imager; Relative Pose Estimation; GNC; Brown's Distortion; Homography; Geometric Distortion; Relative Navigation

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APA (6^th Edition):

Roshan Suresh Kumar, F. (2019). Calibration of Linear Imager Camera for Relative Pose Estimation. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/187541

Chicago Manual of Style (16^th Edition):

Roshan Suresh Kumar, FNU. “Calibration of Linear Imager Camera for Relative Pose Estimation.” 2019. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/187541.

MLA Handbook (7^th Edition):

Roshan Suresh Kumar, FNU. “Calibration of Linear Imager Camera for Relative Pose Estimation.” 2019. Web. 25 Feb 2021.

Vancouver:

Roshan Suresh Kumar F. Calibration of Linear Imager Camera for Relative Pose Estimation. [Internet] [Masters thesis]. Texas A&M University; 2019. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/187541.

Council of Science Editors:

Roshan Suresh Kumar F. Calibration of Linear Imager Camera for Relative Pose Estimation. [Masters Thesis]. Texas A&M University; 2019. Available from: http://hdl.handle.net/1969.1/187541

Texas A&M University

2. Schaeperkoetter, Andrew Vernon. A Comprehensive Comparison Between Angles-Only Initial Orbit Determination Techniques.

Degree: MS, Aerospace Engineering, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10242

► During the last two centuries many methods have been proposed to solve the angles-only initial orbit determination problem. As this problem continues to be relevant… (more)

Subjects/Keywords: Initial Orbit Determination; Gooding; Double R; Gauss; Laplace

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APA (6^th Edition):

Schaeperkoetter, A. V. (2012). A Comprehensive Comparison Between Angles-Only Initial Orbit Determination Techniques. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10242

Chicago Manual of Style (16^th Edition):

Schaeperkoetter, Andrew Vernon. “A Comprehensive Comparison Between Angles-Only Initial Orbit Determination Techniques.” 2012. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10242.

MLA Handbook (7^th Edition):

Schaeperkoetter, Andrew Vernon. “A Comprehensive Comparison Between Angles-Only Initial Orbit Determination Techniques.” 2012. Web. 25 Feb 2021.

Vancouver:

Schaeperkoetter AV. A Comprehensive Comparison Between Angles-Only Initial Orbit Determination Techniques. [Internet] [Masters thesis]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10242.

Council of Science Editors:

Schaeperkoetter AV. A Comprehensive Comparison Between Angles-Only Initial Orbit Determination Techniques. [Masters Thesis]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10242

Texas A&M University

3. Enkh, Mandakh. Bouquet: a Satellite Constellation Visualization Program for Walkers and Lattice Flower Constellations.

Degree: MS, Aerospace Engineering, 2011, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10103

► The development of the Flower Constellation theory offers an expanded framework to utilize constellations of satellites for tangible interests. To realize the full potential of… (more)

Subjects/Keywords: flower constellations; lattice flower constellations; satellites; walker constellations; visualization; simulation; editing; computer application; program

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APA (6^th Edition):

Enkh, M. (2011). Bouquet: a Satellite Constellation Visualization Program for Walkers and Lattice Flower Constellations. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10103

Chicago Manual of Style (16^th Edition):

Enkh, Mandakh. “Bouquet: a Satellite Constellation Visualization Program for Walkers and Lattice Flower Constellations.” 2011. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10103.

MLA Handbook (7^th Edition):

Enkh, Mandakh. “Bouquet: a Satellite Constellation Visualization Program for Walkers and Lattice Flower Constellations.” 2011. Web. 25 Feb 2021.

Vancouver:

Enkh M. Bouquet: a Satellite Constellation Visualization Program for Walkers and Lattice Flower Constellations. [Internet] [Masters thesis]. Texas A&M University; 2011. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10103.

Council of Science Editors:

Enkh M. Bouquet: a Satellite Constellation Visualization Program for Walkers and Lattice Flower Constellations. [Masters Thesis]. Texas A&M University; 2011. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10103

Texas A&M University

4. Hafer, William. Improvement of PNP Problem Computational Efficiency For Known Target Geometry of Cubesats.

Degree: MS, Aerospace Engineering, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10958

► This thesis considers the Perspective-N-Point (PNP) problem with orthogonal target geometry, as seen in the problem of cubesat relative navigation. Cubesats are small spacecraft often… (more)

Subjects/Keywords: PNP problem; P3P problem; Known target geometry; Spacecraft relative navigation from vector measurements

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APA (6^th Edition):

Hafer, W. (2012). Improvement of PNP Problem Computational Efficiency For Known Target Geometry of Cubesats. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10958

Chicago Manual of Style (16^th Edition):

Hafer, William. “Improvement of PNP Problem Computational Efficiency For Known Target Geometry of Cubesats.” 2012. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10958.

MLA Handbook (7^th Edition):

Hafer, William. “Improvement of PNP Problem Computational Efficiency For Known Target Geometry of Cubesats.” 2012. Web. 25 Feb 2021.

Vancouver:

Hafer W. Improvement of PNP Problem Computational Efficiency For Known Target Geometry of Cubesats. [Internet] [Masters thesis]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10958.

Council of Science Editors:

Hafer W. Improvement of PNP Problem Computational Efficiency For Known Target Geometry of Cubesats. [Masters Thesis]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10958

Texas A&M University

5. Yu, Dan. State Estimation of Spatio-Temporal Phenomena.

Degree: PhD, Aerospace Engineering, 2016, Texas A&M University

URL: http://hdl.handle.net/1969.1/159046

► This dissertation addresses the state estimation problem of spatio-temporal phenomena which can be modeled by partial differential equations (PDEs), such as pollutant dispersion in the… (more)

▼ This dissertation addresses the state estimation problem of spatio-temporal phenomena which can be modeled by partial differential equations (PDEs), such as pollutant dispersion in the atmosphere. After discretizing the PDE, the dynamical system has a large number of degrees of freedom (DOF). State estimation using Kalman Filter (KF) is computationally intractable, and hence, a reduced order model (ROM) needs to be constructed first. Moreover, the nonlinear terms, external disturbances or unknown boundary conditions can be modeled as unknown inputs, which leads to an unknown input filtering problem. Furthermore, the performance of KF could be improved by placing sensors at feasible locations. Therefore, the sensor scheduling problem to place multiple mobile sensors is of interest. The first part of the dissertation focuses on model reduction for large scale systems with a large number of inputs/outputs. A commonly used model reduction algorithm, the balanced proper orthogonal decomposition (BPOD) algorithm, is not computationally tractable for large systems with a large number of inputs/outputs. Inspired by the BPOD and randomized algorithms, we propose a randomized proper orthogonal decomposition (RPOD) algorithm and a computationally optimal RPOD (RPOD*) algorithm, which construct an ROM to capture the input-output behaviour of the full order model, while reducing the computational cost of BPOD by orders of magnitude. It is demonstrated that the proposed RPOD_ algorithm could construct the ROM in real-time, and the performance of the proposed algorithms on different advection-diffusion equations. Next, we consider the state estimation problem of linear discrete-time systems with unknown inputs which can be treated as a wide-sense stationary process with rational power spectral density, while no other prior information needs to be known. We propose an autoregressive (AR) model based unknown input realization technique which allows us to recover the input statistics from the output data by solving an appropriate least squares problem, then fit an AR model to the recovered input statistics and construct an innovations model of the unknown inputs using the eigensystem realization algorithm. The proposed algorithm outperforms the augmented two-stage Kalman Filter (ASKF) and the unbiased minimum-variance (UMV) algorithm are shown in several examples. Finally, we propose a framework to place multiple mobile sensors to optimize the long-term performance of KF in the estimation of the state of a PDE. The major challenges are that placing multiple sensors is an NP-hard problem, and the optimization problem is non-convex in general. In this dissertation, first, we construct an ROM using RPOD_ algorithm, and then reduce the feasible sensor locations into a subset using the ROM. The Information Space Receding Horizon Control (I-RHC) approach and a modified Monte Carlo Tree Search (MCTS) approach are applied to solve the sensor scheduling problem using the subset. Various applications have been provided to demonstrate the… Advisors/Committee Members: Chakravorty, Suman (advisor), Junkins, John L. (committee member), Girimaji, Sharath (committee member), Darbha, Swaroop (committee member).

Subjects/Keywords: model reduction; spatio-temporal system; sensor placement; unknown input filtering

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APA (6^th Edition):

Yu, D. (2016). State Estimation of Spatio-Temporal Phenomena. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/159046

Chicago Manual of Style (16^th Edition):

Yu, Dan. “State Estimation of Spatio-Temporal Phenomena.” 2016. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/159046.

MLA Handbook (7^th Edition):

Yu, Dan. “State Estimation of Spatio-Temporal Phenomena.” 2016. Web. 25 Feb 2021.

Vancouver:

Yu D. State Estimation of Spatio-Temporal Phenomena. [Internet] [Doctoral dissertation]. Texas A&M University; 2016. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/159046.

Council of Science Editors:

Yu D. State Estimation of Spatio-Temporal Phenomena. [Doctoral Dissertation]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/159046

Texas A&M University

6. Probe, Austin Breien. Development of a Robotic Simulation Platform for Spacecraft Proximity Operations and Contact Dynamics Experiments.

Degree: MS, Aerospace Engineering, 2013, Texas A&M University

URL: http://hdl.handle.net/1969.1/151932

► A major challenge facing the introduction of new technologies and techniques in space flight is the high cost required to raise the Technological Readiness Level… (more)

Subjects/Keywords: space proximity operations; contact dynamics; robotic motion emulation

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APA (6^th Edition):

Probe, A. B. (2013). Development of a Robotic Simulation Platform for Spacecraft Proximity Operations and Contact Dynamics Experiments. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/151932

Chicago Manual of Style (16^th Edition):

Probe, Austin Breien. “Development of a Robotic Simulation Platform for Spacecraft Proximity Operations and Contact Dynamics Experiments.” 2013. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/151932.

MLA Handbook (7^th Edition):

Probe, Austin Breien. “Development of a Robotic Simulation Platform for Spacecraft Proximity Operations and Contact Dynamics Experiments.” 2013. Web. 25 Feb 2021.

Vancouver:

Probe AB. Development of a Robotic Simulation Platform for Spacecraft Proximity Operations and Contact Dynamics Experiments. [Internet] [Masters thesis]. Texas A&M University; 2013. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/151932.

Council of Science Editors:

Probe AB. Development of a Robotic Simulation Platform for Spacecraft Proximity Operations and Contact Dynamics Experiments. [Masters Thesis]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/151932

Texas A&M University

7. Halder, Abhishek. Probabilistic Methods for Model Validation.

Degree: PhD, Aerospace Engineering, 2014, Texas A&M University

URL: http://hdl.handle.net/1969.1/152677

► This dissertation develops a probabilistic method for validation and verification (V&V) of uncertain nonlinear systems. Existing systems-control literature on model and controller V&V either deal… (more)

▼ This dissertation develops a probabilistic method for validation and verification (V&V) of uncertain nonlinear systems. Existing systems-control literature on model and controller V&V either deal with linear systems with norm-bounded uncertainties,or consider nonlinear systems in set-based and moment based framework. These existing methods deal with model invalidation or falsification, rather than assessing the quality of a model with respect to measured data. In this dissertation, an axiomatic framework for model validation is proposed in probabilistically relaxed sense, that instead of simply invalidating a model, seeks to quantify the "degree of validation". To develop this framework, novel algorithms for uncertainty propagation have been proposed for both deterministic and stochastic nonlinear systems in continuous time. For the deterministic flow, we compute the time-varying joint probability density functions over the state space, by solving the Liouville equation via method-of-characteristics. For the stochastic flow, we propose an approximation algorithm that combines the method-of-characteristics solution of Liouville equation with the Karhunen-Lo eve expansion of process noise, thus enabling an indirect solution of Fokker-Planck equation, governing the evolution of joint probability density functions. The efficacy of these algorithms are demonstrated for risk assessment in Mars entry-descent-landing, and for nonlinear estimation. Next, the V&V problem is formulated in terms of Monge-Kantorovich optimal transport, naturally giving rise to a metric, called Wasserstein metric, on the space of probability densities. It is shown that the resulting computation leads to solving a linear program at each time of measurement availability, and computational complexity results for the same are derived. Probabilistic guarantees in average and worst case sense, are given for the validation oracle resulting from the proposed method. The framework is demonstrated for nonlinear robustness veri cation of F-16 flight controllers, subject to probabilistic uncertainties. Frequency domain interpretations for the proposed framework are derived for linear systems, and its connections with existing nonlinear model validation methods are pointed out. In particular, we show that the asymptotic Wasserstein gap between two single-output linear time invariant systems excited by Gaussian white noise, is the difference between their average gains, up to a scaling by the strength of the input noise. A geometric interpretation of this result allows us to propose an intrinsic normalization of the Wasserstein gap, which in turn allows us to compare it with classical systems-theoretic metrics like v-gap. Next, it is shown that the optimal transport map can be used to automatically refine the model. This model refinement formulation leads to solving a non-smooth convex optimization problem. Examples are given to demonstrate how proximal operator splitting based computation enables numerically solving the same. This method is applied for … Advisors/Committee Members: Bhattacharya, Raktim (advisor), Junkins, John (committee member), Chakravorty, Suman (committee member), Kumar, Panganamala Ramana (committee member).

Subjects/Keywords: model validation; controller verification; refinement; optimal transport; Wasserstein distance; uncertainty propagation

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APA (6^th Edition):

Halder, A. (2014). Probabilistic Methods for Model Validation. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/152677

Chicago Manual of Style (16^th Edition):

Halder, Abhishek. “Probabilistic Methods for Model Validation.” 2014. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/152677.

MLA Handbook (7^th Edition):

Halder, Abhishek. “Probabilistic Methods for Model Validation.” 2014. Web. 25 Feb 2021.

Vancouver:

Halder A. Probabilistic Methods for Model Validation. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/152677.

Council of Science Editors:

Halder A. Probabilistic Methods for Model Validation. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/152677

Texas A&M University

8. Desai, Uri. A Comparative Study of Estimation Models for Satellite Relative Motion.

Degree: MS, Aerospace Engineering, 2013, Texas A&M University

URL: http://hdl.handle.net/1969.1/149297

► The problem of relative spacecraft motion estimation is considered with application to various reference and relative orbits. Mean circular and elliptic orbits are analyzed, with… (more)

▼ The problem of relative spacecraft motion estimation is considered with application to various reference and relative orbits. Mean circular and elliptic orbits are analyzed, with relative orbits ranging in size from 1 km to 10 km. Estimators are built for three propagation models: (i) Gim-Alfriend State Transition Matrix, (ii) the J2-Linearized Equations of Motion for Circular Orbits, and (iii) the Clohessy-Wiltshire Equations of Motion. Two alternative models were developed in an attempt to ac- count for unmodeled nonlinearities: (i) Biased Clohessy-Whiltshire Equations, and (ii) J2 -Linearized State Transition Matrix. Two estimation techniques are presented in an attempt to explore and determine which propagation model minimizes the error residual: the linear Kalman filter is presented under the assumption of vector based, GPS-type measurements; the extended Kalman filter is analyzed assuming angle-range, optical-type measurements. Sampling time is varied to look at the effect of measurement frequency. It is assumed that the orbit of one of the satellites, the chief, is known reasonably well. This work showed that the error residuals from the state estimates were minimized when the propagation technique utilized was the Gim-Alfriend State Transition Matrix. This supports conclusions that are obtained outside of the estimation problem. Additionally, the error residuals obtained when the propagation technique was the Clohessy-Wiltshire Equations is comparable to the more complicated models. Unmodeled nonlinearities affect the magnitude of the error residuals. As expected, the Gim-Alfriend STM comes closest to the truth; for smaller eccentricities (0.005), the Clohessy-Wiltshire EOM show minor deviations from the truth. As the eccentricity increases, the linear models begin to diverge greatly from the true response. The additional two models (the biased CW equations, and the linear STM) show decent performance under specific conditions. The former accounts for some of the unaccounted for nonlinearities. The latter exhibits comparable performance to the Gim-Alfrien STM for circular reference orbits. However, in each case, as the nonlinearity of the problem increases, the accuracy of the model decreases. Advisors/Committee Members: Vadali, Srinivas R (advisor), Junkins, John (committee member), Zelenko, Igor (committee member).

Subjects/Keywords: relative navigation; Clohessy-Wiltshire Equations; Gim-Alfriend State Transition Matrix (GA-STM); estimation

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APA (6^th Edition):

Desai, U. (2013). A Comparative Study of Estimation Models for Satellite Relative Motion. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/149297

Chicago Manual of Style (16^th Edition):

Desai, Uri. “A Comparative Study of Estimation Models for Satellite Relative Motion.” 2013. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/149297.

MLA Handbook (7^th Edition):

Desai, Uri. “A Comparative Study of Estimation Models for Satellite Relative Motion.” 2013. Web. 25 Feb 2021.

Vancouver:

Desai U. A Comparative Study of Estimation Models for Satellite Relative Motion. [Internet] [Masters thesis]. Texas A&M University; 2013. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/149297.

Council of Science Editors:

Desai U. A Comparative Study of Estimation Models for Satellite Relative Motion. [Masters Thesis]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/149297

Texas A&M University

9. Taylor, Bradley Whitten. Experimental Investigation of Helicopter Weight and Mass Center Estimation.

Degree: MS, Aerospace Engineering, 2013, Texas A&M University

URL: http://hdl.handle.net/1969.1/149488

► Real-time estimates of weight and mass center location for helicopters are desirable for flight control and condition-based maintenance purposes. While methods to estimate mass parameters… (more)

Subjects/Keywords: Helicopter; Weight; Mass Center; Estimation

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APA (6^th Edition):

Taylor, B. W. (2013). Experimental Investigation of Helicopter Weight and Mass Center Estimation. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/149488

Chicago Manual of Style (16^th Edition):

Taylor, Bradley Whitten. “Experimental Investigation of Helicopter Weight and Mass Center Estimation.” 2013. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/149488.

MLA Handbook (7^th Edition):

Taylor, Bradley Whitten. “Experimental Investigation of Helicopter Weight and Mass Center Estimation.” 2013. Web. 25 Feb 2021.

Vancouver:

Taylor BW. Experimental Investigation of Helicopter Weight and Mass Center Estimation. [Internet] [Masters thesis]. Texas A&M University; 2013. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/149488.

Council of Science Editors:

Taylor BW. Experimental Investigation of Helicopter Weight and Mass Center Estimation. [Masters Thesis]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/149488

Texas A&M University

10. Kumar, Sandip. Generalized Sampling-Based Feedback Motion Planners.

Degree: PhD, Aerospace Engineering, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10663

► The motion planning problem can be formulated as a Markov decision process (MDP), if the uncertainties in the robot motion and environments can be modeled… (more)

▼ The motion planning problem can be formulated as a Markov decision process (MDP), if the uncertainties in the robot motion and environments can be modeled probabilistically. The complexity of solving these MDPs grow exponentially as the dimension of the problem increases and hence, it is nearly impossible to solve the problem even without constraints. Using hierarchical methods, these MDPs can be transformed into a semi-Markov decision process (SMDP) which only needs to be solved at certain landmark states. In the deterministic robotics motion planning community, sampling based algorithms like probabilistic roadmaps (PRM) and rapidly exploring random trees (RRTs) have been successful in solving very high dimensional deterministic problem. However they are not robust to system with uncertainties in the system dynamics and hence, one of the primary objective of this work is to generalize PRM/RRT to solve motion planning with uncertainty. We first present generalizations of randomized sampling based algorithms PRM and RRT, to incorporate the process uncertainty, and obstacle location uncertainty, termed as "generalized PRM" (GPRM) and "generalized RRT" (GRRT). The controllers used at the lower level of these planners are feedback controllers which ensure convergence of trajectories while mitigating the effects of process uncertainty. The results indicate that the algorithms solve the motion planning problem for a single agent in continuous state/control spaces in the presence of process uncertainty, and constraints such as obstacles and other state/input constraints. Secondly, a novel adaptive sampling technique, termed as "adaptive GPRM" (AGPRM), is proposed for these generalized planners to increase the efficiency and overall success probability of these planners. It was implemented on high-dimensional robot n-link manipulators, with up to 8 links, i.e. in a 16-dimensional state-space. The results demonstrate the ability of the proposed algorithm to handle the motion planning problem for highly non-linear systems in very high-dimensional state space. Finally, a solution methodology, termed the "multi-agent AGPRM" (MAGPRM), is proposed to solve the multi-agent motion planning problem under uncertainty. The technique uses a existing solution technique to the multiple traveling salesman problem (MTSP) in conjunction with GPRM. For real-time implementation, an ?inter-agent collision detection and avoidance? module was designed which ensures that no two agents collide at any time-step. Algorithm was tested on teams of homogeneous and heterogeneous agents in cluttered obstacle space and the algorithm demonstrate the ability to handle such problems in continuous state/control spaces in presence of process uncertainty. Advisors/Committee Members: Chakravorty, Suman (advisor), Amato, Nancy (committee member), Bhattacharya, Raktim (committee member), Junkins, John (committee member), Valasek, John (committee member).

Subjects/Keywords: Motion planning; Probabilistic RoadMaps (PRM); Semi-Markov Decision Process (SMDP); uncertainty, adaptive sampling; multi-agent motion planning problem; Multiple traveling salesman problem (MTSP); non-holonomic; heterogeneous agents; motion uncertainty; process uncertainty; collision detection; collision avoidance

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APA (6^th Edition):

Kumar, S. (2012). Generalized Sampling-Based Feedback Motion Planners. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10663

Chicago Manual of Style (16^th Edition):

Kumar, Sandip. “Generalized Sampling-Based Feedback Motion Planners.” 2012. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10663.

MLA Handbook (7^th Edition):

Kumar, Sandip. “Generalized Sampling-Based Feedback Motion Planners.” 2012. Web. 25 Feb 2021.

Vancouver:

Kumar S. Generalized Sampling-Based Feedback Motion Planners. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10663.

Council of Science Editors:

Kumar S. Generalized Sampling-Based Feedback Motion Planners. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10663

Texas A&M University

11. Woodbury, Drew Patton. Accounting for Parameter Uncertainty in Reduced-Order Static and Dynamic Systems.

Degree: PhD, Aerospace Engineering, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10220

► Parametric uncertainty is one of many possible causes of divergence for the Kalman filter. Frequently, state estimation errors caused by imperfect model parameters are reduced… (more)

▼ Parametric uncertainty is one of many possible causes of divergence for the Kalman filter. Frequently, state estimation errors caused by imperfect model parameters are reduced by including the uncertain parameters as states (i.e., augmenting the state vector). For many situations, this not only improves the state estimates, but also improves the accuracy and precision of the parameters themselves. Unfortunately, not all filters benefit from this augmentation due to computational restrictions or because the parameters are poorly observable. A parameter with low observability (e.g., a set of high order gravity coefficients, a set of camera offsets, lens calibration controls, etc.) may not acquire enough measurements along a particular trajectory to improve the parameter's accuracy, which can cause detrimental effects in the performance of the augmented filter. The problem is then how to reduce the dimension of the augmented state vector while minimizing information loss. This dissertation explored possible implementations of reduced-order filters which decrease computational loads while also minimizing state estimation errors. A theoretically rigorous approach using the ?consider" methodology was taken at discrete time intervals were explored for linear systems. The continuous dynamics, discretely measured (continuous-discrete) model was also expanded for use with nonlinear systems. Additional techniques for reduced-order filtering are presented including the use of additive process noise, an alternative consider derivation, and the minimum variance reduced-order filter. Multiple simulation examples are provided to help explain critical concepts. Finally, two hardware applications are also included to show the validity of the theory for real world applications. It was shown that the minimum variance consider Kalman filter (MVCKF) is the best reduced-order filter to date both theoretically and through hardware and software applications. The consider method of estimation provides a compromise between ignoring parameter error and completely accounting for it in a probabilistic sense. Based on multiple measures of optimality, the consider filtering framework can be used to account for parameter error without directly estimating any or all of the parameters. Furthermore, by accounting for the parameter error, the consider approach provides a rigorous path to improve state estimation through the reduction of both state estimation error and with a consistent variance estimate. While using the augmented state vector to estimate both states and parameters may further improve those estimates, the consider estimation framework is an attractive alternative for complex and computationally intensive systems, and provides a well justified path for parameter order reduction. Advisors/Committee Members: Junkins, John L. (advisor), Mortari, Daniele (committee member), Pollock, Thomas (committee member), Parlos, Alexander (committee member), Crassidis, John (committee member).

Subjects/Keywords: estimation; Kalman filter; reduced order; minimum variance filtering

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APA (6^th Edition):

Woodbury, D. P. (2012). Accounting for Parameter Uncertainty in Reduced-Order Static and Dynamic Systems. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10220

Chicago Manual of Style (16^th Edition):

Woodbury, Drew Patton. “Accounting for Parameter Uncertainty in Reduced-Order Static and Dynamic Systems.” 2012. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10220.

MLA Handbook (7^th Edition):

Woodbury, Drew Patton. “Accounting for Parameter Uncertainty in Reduced-Order Static and Dynamic Systems.” 2012. Web. 25 Feb 2021.

Vancouver:

Woodbury DP. Accounting for Parameter Uncertainty in Reduced-Order Static and Dynamic Systems. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10220.

Council of Science Editors:

Woodbury DP. Accounting for Parameter Uncertainty in Reduced-Order Static and Dynamic Systems. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10220

Texas A&M University

12. Read, Julie Louise. Modified Chebyshev Picard Iteration: Integration of Perturbed Motion using Modified Equinoctial Elements.

Degree: PhD, Aerospace Engineering, 2016, Texas A&M University

URL: http://hdl.handle.net/1969.1/159095

► The topic of this dissertation is the fusion of a novel integration method, Modified Chebyshev Picard Iteration (MCPI), with Gauss' Variational Equations using a set… (more)

Subjects/Keywords: Orbital Mechanics; Parallel Processing; Numerical Integration; Modified Chebyshev Picard Iteration; MCPI; Modified Equinoctial Elements; Chebyshev Polynomials

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APA (6^th Edition):

Read, J. L. (2016). Modified Chebyshev Picard Iteration: Integration of Perturbed Motion using Modified Equinoctial Elements. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/159095

Chicago Manual of Style (16^th Edition):

Read, Julie Louise. “Modified Chebyshev Picard Iteration: Integration of Perturbed Motion using Modified Equinoctial Elements.” 2016. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/159095.

MLA Handbook (7^th Edition):

Read, Julie Louise. “Modified Chebyshev Picard Iteration: Integration of Perturbed Motion using Modified Equinoctial Elements.” 2016. Web. 25 Feb 2021.

Vancouver:

Read JL. Modified Chebyshev Picard Iteration: Integration of Perturbed Motion using Modified Equinoctial Elements. [Internet] [Doctoral dissertation]. Texas A&M University; 2016. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/159095.

Council of Science Editors:

Read JL. Modified Chebyshev Picard Iteration: Integration of Perturbed Motion using Modified Equinoctial Elements. [Doctoral Dissertation]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/159095

Texas A&M University

13. Conway, Dylan Taylor. Vision-Aided Navigation: Improved Measurements Models and a Data Driven Approach.

Degree: PhD, Aerospace Engineering, 2016, Texas A&M University

URL: http://hdl.handle.net/1969.1/159100

► Vision-aided navigation is the process of fusing data from visual cameras with other information sources to provide vehicle state estimation. Fusing information from multiple sources… (more)

Subjects/Keywords: Navigation; Computer vision; Robust estimation

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APA (6^th Edition):

Conway, D. T. (2016). Vision-Aided Navigation: Improved Measurements Models and a Data Driven Approach. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/159100

Chicago Manual of Style (16^th Edition):

Conway, Dylan Taylor. “Vision-Aided Navigation: Improved Measurements Models and a Data Driven Approach.” 2016. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/159100.

MLA Handbook (7^th Edition):

Conway, Dylan Taylor. “Vision-Aided Navigation: Improved Measurements Models and a Data Driven Approach.” 2016. Web. 25 Feb 2021.

Vancouver:

Conway DT. Vision-Aided Navigation: Improved Measurements Models and a Data Driven Approach. [Internet] [Doctoral dissertation]. Texas A&M University; 2016. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/159100.

Council of Science Editors:

Conway DT. Vision-Aided Navigation: Improved Measurements Models and a Data Driven Approach. [Doctoral Dissertation]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/159100

Texas A&M University

14. Aures-Cavalieri, Kurt D. Incomplete Information Pursuit-Evasion Games with Applications to Spacecraft Rendezvous and Missile Defense.

Degree: PhD, Aerospace Engineering, 2014, Texas A&M University

URL: http://hdl.handle.net/1969.1/154101

► Pursuit-evasion games reside at the intersection of game theory and optimal control theory. They are often referred to as differential games because the dynamics of… (more)

▼ Pursuit-evasion games reside at the intersection of game theory and optimal control theory. They are often referred to as differential games because the dynamics of the relative system are modeled by the pursuer and evader differential equations of motion. Pursuit-evasion games diverge from traditional optimal control problems due to the participation of multiple intelligent agents with conflicting goals. Individual goals of each agent are defined through multiple cost functions and determine how each player will behave throughout the game. The optimal performance of each player is dependent upon how much knowledge they have about themselves, their opponent, and the system. Complete information games represent the ideal case in which each player can truly play optimally because all pertinent information about the game is readily available to each player. Player performance in a pursuit-evasion game greatly diminishes as information availability moves further from the ideal case and approaches the most realistic scenarios. Methods to maintain satisfactory performance in the presence of incomplete, imperfect, and uncertain information games is very desirable due to the application of optimal pursuit-evasion solutions to high-risk missions including spacecraft rendezvous and missile interception. Behavior learning techniques can be used to estimate the strategy of an opponent and augment the pursuit-evasion game into a one-sided optimal control problem. The application of behavior learning is identified in final-time-fixed, in finite-horizon, and final-time-free situations. A twostep dynamic inversion process is presented to fit systems with nonlinear kinematics and dynamics into the behavior learning framework for continuous, linear-quadratic games. These techniques are applied to minimum-time, spacecraft reorientation, and missile interception examples to illustrate the advantage of these techniques in real-world applications when essential information is unavailable. Advisors/Committee Members: Hurtado, John E (advisor), Junkins, John L (advisor), Vadali, Srinivas R (committee member), Datta, Aniruddha (committee member).

Subjects/Keywords: differential games; pursuit-evasion, game theory; estimation; optimal control; dynamic inversion; behavior learning; spacecraft rendezvous; missile defense; missile interception

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APA (6^th Edition):

Aures-Cavalieri, K. D. (2014). Incomplete Information Pursuit-Evasion Games with Applications to Spacecraft Rendezvous and Missile Defense. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/154101

Chicago Manual of Style (16^th Edition):

Aures-Cavalieri, Kurt D. “Incomplete Information Pursuit-Evasion Games with Applications to Spacecraft Rendezvous and Missile Defense.” 2014. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/154101.

MLA Handbook (7^th Edition):

Aures-Cavalieri, Kurt D. “Incomplete Information Pursuit-Evasion Games with Applications to Spacecraft Rendezvous and Missile Defense.” 2014. Web. 25 Feb 2021.

Vancouver:

Aures-Cavalieri KD. Incomplete Information Pursuit-Evasion Games with Applications to Spacecraft Rendezvous and Missile Defense. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/154101.

Council of Science Editors:

Aures-Cavalieri KD. Incomplete Information Pursuit-Evasion Games with Applications to Spacecraft Rendezvous and Missile Defense. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/154101

Texas A&M University

15. Satak, Neha. Behavior Learning in Differential Games and Reorientation Maneuvers.

Degree: PhD, Aerospace Engineering, 2013, Texas A&M University

URL: http://hdl.handle.net/1969.1/149467

► The purpose of this dissertation is to apply behavior learning concepts to incomplete-information continuous time games. Realistic game scenarios are often incomplete-information games in which… (more)

▼ The purpose of this dissertation is to apply behavior learning concepts to incomplete-information continuous time games. Realistic game scenarios are often incomplete-information games in which the players withhold information. A player may not know its opponent’s objectives and strategies prior to the start of the game. This lack of information can limit the player’s ability to play optimally. If the player can observe the opponent’s actions, it can better optimize its achievements by taking corrective actions. In this research, a framework to learn an opponent’s behavior and take corrective actions is developed. The framework will allow a player to observe the opponent’s actions and formulate behavior models. The developed behavior model can then be utilized to ﬁnd the best actions for the player that optimizes the player’s objective function. In addition, the framework proposes that the player plays a safe strategy at the beginning of the game. A safe strategy is defined in this research as a strategy that guarantees a minimum pay-off to the player independent of the other player’s actions. During the initial part of the game, the player will play the safe strategy until it learns the opponent’s behavior. Two methods to develop behavior models that differ in the formulation of the behavior model are proposed. The ﬁrst method is the Cost-Strategy Recognition (CSR) method in which the player formulates an objective function and a strategy for the opponent. The opponent is presumed to be rational and therefore will play to optimize its objective function. The strategy of the opponent is dependent on the information available to the opponent about other players in the game. A strategy formulation presumes a certain level of information available to the opponent. The previous observations of the opponent’s actions are used to estimate the parameters of the formulated behavior model. The estimated behavior model predicts the opponent’s future actions. The second method is the Direct Approximation of Value Function (DAVF) method. In this method, unlike the CSR method, the player formulates an objective function for the opponent but does not formulates a strategy directly; rather, indirectly the player assumes that the opponent is playing optimally. Thus, a value function satisfying the HJB equation corresponding to the opponent’s cost function exists. The DAVF method ﬁnds an approximate solution for the value function based on previous observations of the opponent’s control. The approximate solution to the value function is then used to predict the opponent’s future behavior. Game examples in which only a single player is learning its opponent’s behavior are simulated. Subsequently, examples in which both players in a two-player game are learning each other’s behavior are simulated. In the second part of this research, a reorientation control maneuver for a spinning spacecraft will be developed. This will aid the application of behavior learning and differential games concepts to the specific scenario involving… Advisors/Committee Members: Hurtado, John E. (advisor), Junkins, John L. (committee member), Vadali, Srinivas R. (committee member), Bhattacharyya, Shankar P. (committee member).

Subjects/Keywords: Differential Games; Reorientation Maneuvers; Behavior Learning

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

APA (6^th Edition):

Satak, N. (2013). Behavior Learning in Differential Games and Reorientation Maneuvers. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/149467

Chicago Manual of Style (16^th Edition):

Satak, Neha. “Behavior Learning in Differential Games and Reorientation Maneuvers.” 2013. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/149467.

MLA Handbook (7^th Edition):

Satak, Neha. “Behavior Learning in Differential Games and Reorientation Maneuvers.” 2013. Web. 25 Feb 2021.

Vancouver:

Satak N. Behavior Learning in Differential Games and Reorientation Maneuvers. [Internet] [Doctoral dissertation]. Texas A&M University; 2013. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/149467.

Council of Science Editors:

Satak N. Behavior Learning in Differential Games and Reorientation Maneuvers. [Doctoral Dissertation]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/149467

Texas A&M University

16. Restrepo, Carolina 1982-. An Analysis Tool for Flight Dynamics Monte Carlo Simulations.

Degree: PhD, Aerospace Engineering, 2011, Texas A&M University

URL: http://hdl.handle.net/1969.1/150935

► Spacecraft design is inherently difficult due to the nonlinearity of the systems involved as well as the expense of testing hardware in a realistic environment.… (more)

▼ Spacecraft design is inherently difficult due to the nonlinearity of the systems involved as well as the expense of testing hardware in a realistic environment. The number and cost of flight tests can be reduced by performing extensive simulation and analysis work to understand vehicle operating limits and identify circumstances that lead to mission failure. A Monte Carlo simulation approach that varies a wide range of physical parameters is typically used to generate thousands of test cases. Currently, the data analysis process for a fully integrated spacecraft is mostly performed manually on a case-by-case basis, often requiring several analysts to write additional scripts in order to sort through the large data sets. There is no single method that can be used to identify these complex variable interactions in a reliable and timely manner as well as be applied to a wide range of flight dynamics problems. This dissertation investigates the feasibility of a unified, general approach to the process of analyzing flight dynamics Monte Carlo data. The main contribution of this work is the development of a systematic approach to finding and ranking the most influential variables and combinations of variables for a given system failure. Specifically, a practical and interactive analysis tool that uses tractable pattern recognition methods to automate the analysis process has been developed. The analysis tool has two main parts: the analysis of individual influential variables and the analysis of influential combinations of variables. This dissertation describes in detail the two main algorithms used: kernel density estimation and nearest neighbors. Both are non-parametric density estimation methods that are used to analyze hundreds of variables and combinations thereof to provide an analyst with insightful information about the potential cause for a specific system failure. Examples of dynamical systems analysis tasks using the tool are provided. Advisors/Committee Members: Hurtado, John E (advisor), Junkins, John L (committee member), Bhattacharya, Raktim (committee member), Gutierrez-Osuna, Ricardo (committee member).

Subjects/Keywords: spacecraft design; nearest neighbors; kernel density estimation; guidance, navigation, and control; pattern recognition; data analysis; Monte Carlo simulation

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

APA (6^th Edition):

Restrepo, C. 1. (2011). An Analysis Tool for Flight Dynamics Monte Carlo Simulations. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/150935

Chicago Manual of Style (16^th Edition):

Restrepo, Carolina 1982-. “An Analysis Tool for Flight Dynamics Monte Carlo Simulations.” 2011. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/150935.

MLA Handbook (7^th Edition):

Restrepo, Carolina 1982-. “An Analysis Tool for Flight Dynamics Monte Carlo Simulations.” 2011. Web. 25 Feb 2021.

Vancouver:

Restrepo C1. An Analysis Tool for Flight Dynamics Monte Carlo Simulations. [Internet] [Doctoral dissertation]. Texas A&M University; 2011. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/150935.

Council of Science Editors:

Restrepo C1. An Analysis Tool for Flight Dynamics Monte Carlo Simulations. [Doctoral Dissertation]. Texas A&M University; 2011. Available from: http://hdl.handle.net/1969.1/150935

Texas A&M University

17. Karimi, Reza. Designing An Interplanetary Autonomous Spacecraft Navigation System Using Visible Planets.

Degree: PhD, Aerospace Engineering, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11084

► A perfect duality exists between the problem of space-based orbit determination from line-of-sight measurements and the problem of designing an interplanetary autonomous navigation system. Mathematically,… (more)

▼ A perfect duality exists between the problem of space-based orbit determination from line-of-sight measurements and the problem of designing an interplanetary autonomous navigation system. Mathematically, these two problems are equivalent. Any method solving the first problem can be used to solve the second one and, vice versa. While the first problem estimates the observed unknown object orbit using the known observer orbit, the second problem does exactly the opposite (e.g. the spacecraft observes a known visible planet). However, in an interplanetary navigation problem, in addition to the measurement noise, the following "perturbations" must be considered: 1) light-time effect due to the finite speed of light and large distances between the observer and planets, and 2) light aberration including special relativistic effect. These two effects require corrections of the initial orbit estimation problems. Because of the duality problem of space-based orbit determination, several new techniques of angles-only Initial Orbit Determination (IOD) are here developed which are capable of using multiple observations and provide higher orbit estimation accuracy and also they are not suffering from some of the limitations associated with the classical and some newly developed methods of initial orbit determination. Using multiple observations make these techniques suitable for the coplanar orbit determination problems which are the case for the spacecraft navigation using visible planets as the solar system planets are all almost coplanar. Four new IOD techniques were developed and Laplace method was modified. For the autonomous navigation purpose, Extended Kalman Filter (EKF) is employed. The output of the IOD algorithm is then used as the initial condition to extended Kalman filter. The two "perturbations" caused by light-time effect and stellar aberration including special relativistic effect also need to be taken into consideration and corrections should be implemented into the extended Kalman filter scheme for the autonomous spacecraft navigation problem. Advisors/Committee Members: Mortari, Daniele (advisor), Junkins, John L. (committee member), Vadali, Srinivas R. (committee member), Hurtado, Johnny E. (committee member), Bhattacharyya, Shankar (committee member).

Subjects/Keywords: Initial Orbit Determination; Spacecraft Navigation; Extended Kalman Filter; Light-time correction; light Aberration

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APA (6^th Edition):

Karimi, R. (2012). Designing An Interplanetary Autonomous Spacecraft Navigation System Using Visible Planets. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11084

Chicago Manual of Style (16^th Edition):

Karimi, Reza. “Designing An Interplanetary Autonomous Spacecraft Navigation System Using Visible Planets.” 2012. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11084.

MLA Handbook (7^th Edition):

Karimi, Reza. “Designing An Interplanetary Autonomous Spacecraft Navigation System Using Visible Planets.” 2012. Web. 25 Feb 2021.

Vancouver:

Karimi R. Designing An Interplanetary Autonomous Spacecraft Navigation System Using Visible Planets. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11084.

Council of Science Editors:

Karimi R. Designing An Interplanetary Autonomous Spacecraft Navigation System Using Visible Planets. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11084

Texas A&M University

18. Kumar, Mrinal. Design and Analysis of Stochastic Dynamical Systems with Fokker-Planck Equation.

Degree: PhD, Aerospace Engineering, 2011, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7500

► This dissertation addresses design and analysis aspects of stochastic dynamical systems using Fokker-Planck equation (FPE). A new numerical methodology based on the partition of unity… (more)

▼ This dissertation addresses design and analysis aspects of stochastic dynamical systems using Fokker-Planck equation (FPE). A new numerical methodology based on the partition of unity meshless paradigm is developed to tackle the greatest hurdle in successful numerical solution of FPE, namely the curse of dimensionality. A local variational form of the Fokker-Planck operator is developed with provision for h- and p- refinement. The resulting high dimensional weak form integrals are evaluated using quasi Monte-Carlo techniques. Spectral analysis of the discretized Fokker- Planck operator, followed by spurious mode rejection is employed to construct a new semi-analytical algorithm to obtain near real-time approximations of transient FPE response of high dimensional nonlinear dynamical systems in terms of a reduced subset of admissible modes. Numerical evidence is provided showing that the curse of dimensionality associated with FPE is broken by the proposed technique, while providing problem size reduction of several orders of magnitude. In addition, a simple modification of norm in the variational formulation is shown to improve quality of approximation significantly while keeping the problem size fixed. Norm modification is also employed as part of a recursive methodology for tracking the optimal finite domain to solve FPE numerically. The basic tools developed to solve FPE are applied to solving problems in nonlinear stochastic optimal control and nonlinear filtering. A policy iteration algorithm for stochastic dynamical systems is implemented in which successive approximations of a forced backward Kolmogorov equation (BKE) is shown to converge to the solution of the corresponding Hamilton Jacobi Bellman (HJB) equation. Several examples, including a four-state missile autopilot design for pitch control, are considered. Application of the FPE solver to nonlinear filtering is considered with special emphasis on situations involving long durations of propagation in between measurement updates, which is implemented as a weak form of the Bayes rule. A nonlinear filter is formulated that provides complete probabilistic state information conditioned on measurements. Examples with long propagation times are considered to demonstrate benefits of using the FPE based approach to filtering. Advisors/Committee Members: Chakravorty, Suman (advisor), Junkins, John L. (advisor), Vadali, Srinivas R. (committee member), Hyland, David (committee member), Bhattacharyya, Shankar P. (committee member).

Subjects/Keywords: Stochastic dynamical systems; Fokker-Planck equation; Meshless finite-element methods; Nonlinear filtering; Stochastic optimal control; Partition of unity finite-element method

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APA (6^th Edition):

Kumar, M. (2011). Design and Analysis of Stochastic Dynamical Systems with Fokker-Planck Equation. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7500

Chicago Manual of Style (16^th Edition):

Kumar, Mrinal. “Design and Analysis of Stochastic Dynamical Systems with Fokker-Planck Equation.” 2011. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7500.

MLA Handbook (7^th Edition):

Kumar, Mrinal. “Design and Analysis of Stochastic Dynamical Systems with Fokker-Planck Equation.” 2011. Web. 25 Feb 2021.

Vancouver:

Kumar M. Design and Analysis of Stochastic Dynamical Systems with Fokker-Planck Equation. [Internet] [Doctoral dissertation]. Texas A&M University; 2011. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7500.

Council of Science Editors:

Kumar M. Design and Analysis of Stochastic Dynamical Systems with Fokker-Planck Equation. [Doctoral Dissertation]. Texas A&M University; 2011. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7500

Texas A&M University

19. Macomber, Brent David. Enhancements to Chebyshev-Picard Iteration Efficiency for Generally Perturbed Orbits and Constrained Dynamical Systems.

Degree: PhD, Aerospace Engineering, 2015, Texas A&M University

URL: http://hdl.handle.net/1969.1/155745

► Modified Chebyshev Picard Iteration (MCPI) is an iterative numerical method for solution of Ordinary Differential Equations (ODEs). This dissertation presents a body of work that… (more)

▼ Modified Chebyshev Picard Iteration (MCPI) is an iterative numerical method for solution of Ordinary Differential Equations (ODEs). This dissertation presents a body of work that serves to enhance the overall performance and the algorithmic automation of MCPI, applied to the problem of perturbed orbit propagation. Additionally, an MCPI framework is derived that greatly improves MCPI performance for ODE systems that intrinsically have associated conserved quantities. Leveraging these developments, software libraries are presented that are designed to make MCPI more accessible and automated, both for the problem of orbit propagation, and for general ODE systems. The work outlined in this document is the result of an effort to promote MCPI from an algorithm of academic interest to a broadly applicable toolset for general use by researchers worldwide in all disciplines. MCPI is able to numerically propagate perturbed orbits to arbitrarily high solution accuracy, bounded by the limits of numerical precision. The improvements to MCPI for orbit propagation are focused on decreasing the computational cost of high-accuracy propagation in a two-fold manner; by reducing the number of required iterations necessary to achieve convergence, and decreasing the computational cost per iteration. Typically, the spherical harmonic gravity function evaluations are the most computationally expensive part of perturbed orbit propagation, so the strategies for reducing the cost per iteration focus on techniques for reducing the cost of gravity series evaluations. Additionally, automated tuning parameter selection logic is introduced to enable MCPI to propagate large batches of perturbed orbits, without the necessity of a user in the loop. By making use of an associated conserved quantity within applicable ODE systems, MCPI is shown to be able to achieve much higher performance. A first order and a second order constrained MCPI formulation are developed that are able to vastly reduce the required number of iterations for convergence, increase the achievable segment length, and increase the overall solution accuracy for a given convergence threshold. Software libraries are presented with the goal of encouraging widespread use of the MCPI method. Serial libraries are available for general ODE systems, akin to the Matlab ODE** methods. More specialized libraries, making use of the computational improvements and automated tuning, are available for perturbed orbit propagation. A parallel framework based upon the orbit propagation libraries is presented that is designed for space catalog maintenance, uncertainty propagation, or conjunction analysis. Advisors/Committee Members: Junkins, John L (advisor), Datta, Aniruddha (committee member), Hurtado, John E (committee member), Turner, James D (committee member).

Subjects/Keywords: Numerical Methods; Ordinary Differential Equations; Parallel Computing; Orbit Propagation; Space Situational Awareness

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APA (6^th Edition):

Macomber, B. D. (2015). Enhancements to Chebyshev-Picard Iteration Efficiency for Generally Perturbed Orbits and Constrained Dynamical Systems. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/155745

Chicago Manual of Style (16^th Edition):

Macomber, Brent David. “Enhancements to Chebyshev-Picard Iteration Efficiency for Generally Perturbed Orbits and Constrained Dynamical Systems.” 2015. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/155745.

MLA Handbook (7^th Edition):

Macomber, Brent David. “Enhancements to Chebyshev-Picard Iteration Efficiency for Generally Perturbed Orbits and Constrained Dynamical Systems.” 2015. Web. 25 Feb 2021.

Vancouver:

Macomber BD. Enhancements to Chebyshev-Picard Iteration Efficiency for Generally Perturbed Orbits and Constrained Dynamical Systems. [Internet] [Doctoral dissertation]. Texas A&M University; 2015. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/155745.

Council of Science Editors:

Macomber BD. Enhancements to Chebyshev-Picard Iteration Efficiency for Generally Perturbed Orbits and Constrained Dynamical Systems. [Doctoral Dissertation]. Texas A&M University; 2015. Available from: http://hdl.handle.net/1969.1/155745

Texas A&M University

20. Aghamohammadi, Aliakbar. Feedback-based Information Roadmap (FIRM): Graph-based Estimation and Control of Robotic Systems Under Uncertainty.

Degree: PhD, Computer Engineering, 2014, Texas A&M University

URL: http://hdl.handle.net/1969.1/152857

► This dissertation addresses the problem of stochastic optimal control with imperfect measurements. The main application of interest is robot motion planning under uncertainty. In the… (more)

▼ This dissertation addresses the problem of stochastic optimal control with imperfect measurements. The main application of interest is robot motion planning under uncertainty. In the presence of process uncertainty and imperfect measurements, the system's state is unknown and a state estimation module is required to provide the information-state (belief), which is the probability distribution function (pdf) over all possible states. Accordingly, successful robot operation in such a setting requires reasoning about the evolution of information-state and its quality in future time steps. In its most general form, this is modeled as a Partially-Observable Markov Decision Process (POMDP) problem. Unfortunately, however, the exact solution of this problem over continuous spaces in the presence of constraints is computationally intractable. Correspondingly, state-of-the-art methods that provide approximate solutions are limited to problems with short horizons and small domains. The main challenge for these problems is the exponential growth of the search tree in the information space, as well as the dependency of the entire search tree on the initial belief. Inspired by sampling-based (roadmap-based) methods, this dissertation proposes a method to construct a "graph" in information space, called Feedback-based Information RoadMap (FIRM). Each FIRM node is a probability distribution and each FIRM edge is a local controller. The concept of belief stabilizers is introduced as a way to steer the current belief toward FIRM nodes and induce belief reachability. The solution provided by the FIRM framework is a feedback law over the information space, which is obtained by switching among locally distributed feedback controllers. Exploiting such a graph in planning, the intractable POMDP problem over continuous spaces is reduced to a tractable MDP (Markov Decision Process) problem over the graph (FIRM) nodes. FIRM is the first graph generated in the information space that preserves the principle of optimality, i.e., the costs associated with different edges of FIRM are independent of each other. Unlike the forward search methods on tree-structures, the plans produced by FIRM are independent of the initial belief (i.e., plans are query-independent). As a result, they are robust and reliable. They are robust in the sense that if the system's belief deviates from the planned belief, then replanning is feasible in real-time, as the computed solution is a feedback over the entire belief graph. Computed plans are reliable in the sense that the probability of violating constraints (e.g., hitting obstacles) can be seamlessly incorporated into the planning law. Moreover, FIRM is a scalable framework, as the computational complexity of its construction is linear in the size of underlying graph as opposed to state-of-the-art methods whose complexity is exponential in the size of underlying graph. In addition to the abstract framework, we present concrete FIRM instantiations for three main classes of robotic systems: holonomic,… Advisors/Committee Members: Amato, Nancy M (advisor), Chakravorty, Suman (advisor), Kumar, P. R. (committee member), Shell, Dylan (committee member), Junkins, John (committee member), Gutierrez-Osuna, Ricardo (committee member).

Subjects/Keywords: Motion Planning; Stochastic Control; POMDP; Information; FIRM; Feedback-based Information Roadmap; belief; Robot

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APA (6^th Edition):

Aghamohammadi, A. (2014). Feedback-based Information Roadmap (FIRM): Graph-based Estimation and Control of Robotic Systems Under Uncertainty. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/152857

Chicago Manual of Style (16^th Edition):

Aghamohammadi, Aliakbar. “Feedback-based Information Roadmap (FIRM): Graph-based Estimation and Control of Robotic Systems Under Uncertainty.” 2014. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/152857.

MLA Handbook (7^th Edition):

Aghamohammadi, Aliakbar. “Feedback-based Information Roadmap (FIRM): Graph-based Estimation and Control of Robotic Systems Under Uncertainty.” 2014. Web. 25 Feb 2021.

Vancouver:

Aghamohammadi A. Feedback-based Information Roadmap (FIRM): Graph-based Estimation and Control of Robotic Systems Under Uncertainty. [Internet] [Doctoral dissertation]. Texas A&M University; 2014. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/152857.

Council of Science Editors:

Aghamohammadi A. Feedback-based Information Roadmap (FIRM): Graph-based Estimation and Control of Robotic Systems Under Uncertainty. [Doctoral Dissertation]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/152857

21. Whitten, William Daniel. Improving the Robustness of Monocular Vision-Aided Navigation for Multirotors through Integrated Estimation and Guidance.

Degree: MS, Aerospace Engineering, 2017, Texas A&M University

URL: http://hdl.handle.net/1969.1/161526

► Multirotors could be used to autonomously perform tasks in search-and-rescue, reconnaissance, or infrastructure-monitoring applications. In these environments, the vehicle may have limited or degraded GPS… (more)

▼ Multirotors could be used to autonomously perform tasks in search-and-rescue, reconnaissance, or infrastructure-monitoring applications. In these environments, the vehicle may have limited or degraded GPS access. Researchers have investigated methods for simultaneous localization and mapping (SLAM) using on-board vision sensors, allowing vehicles to navigate in GPS-denied environments. In particular, SLAM solutions based on a monocular camera offer low-cost, low-weight, and accurate navigation indoors and outdoors without explicit range limitations. However, a monocular camera is a bearing-only sensor. Additional sensors are required to achieve metric pose estimation, and the structure of a scene can only be recovered through camera motion. Because of these challenges, the performance of monocular-based navigation solutions is typically very sensitive to the environment and the vehicle’s trajectory. This work proposes an integrated estimation and guidance approach for improving the robustness of monocular SLAM to environmental uncertainty. It is specifically intended for a multirotor carrying a monocular camera, downward-facing rangefinder, and inertial measurement unit (IMU). A guidance maneuver is proposed that takes advantage of the metric rangefinder measurements. When the environmental uncertainty is high, the vehicle simply moves up and down, initializing features with a confident and accurate baseline. In order to demonstrate this technique, a vision-aided navigation solution is implemented which includes a unique approach to feature covariance initialization that is based on consider least squares. Features are only initialized if there is enough information to accurately triangulate their position, providing an indirect metric of environmental uncertainty that could be used to signal the guidance maneuver. The navigation filter is validated using hardware and simulated data. Finally, simulations show that the proposed initialization maneuver is a simple, practical, and effective way to improve the robustness of monocular-vision-aided-navigation and could increase the amount of autonomy that GPS-denied multirotors are capable of achieving. Advisors/Committee Members: Hurtado, John (advisor), Junkins, John (advisor), Rathinam, Sivakumar (committee member).

Subjects/Keywords: Simultaneous Localization and Mapping; SLAM; monocular; camera; aerospace; engineering; computer vision; estimation; navigation; drone; quadcopter; autonomous; guidance; inertial measurement unit; IMU; robotics; images

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APA (6^th Edition):

Whitten, W. D. (2017). Improving the Robustness of Monocular Vision-Aided Navigation for Multirotors through Integrated Estimation and Guidance. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/161526

Chicago Manual of Style (16^th Edition):

Whitten, William Daniel. “Improving the Robustness of Monocular Vision-Aided Navigation for Multirotors through Integrated Estimation and Guidance.” 2017. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/161526.

MLA Handbook (7^th Edition):

Whitten, William Daniel. “Improving the Robustness of Monocular Vision-Aided Navigation for Multirotors through Integrated Estimation and Guidance.” 2017. Web. 25 Feb 2021.

Vancouver:

Whitten WD. Improving the Robustness of Monocular Vision-Aided Navigation for Multirotors through Integrated Estimation and Guidance. [Internet] [Masters thesis]. Texas A&M University; 2017. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/161526.

Council of Science Editors:

Whitten WD. Improving the Robustness of Monocular Vision-Aided Navigation for Multirotors through Integrated Estimation and Guidance. [Masters Thesis]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/161526

22. Davis, Jeremy John. Constellation Reconfiguration: Tools and Analysis.

Degree: PhD, Aerospace Engineering, 2011, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8325

► Constellation reconfi guration consists of transforming an initial constellation of satellites into some final constellation of satellites to maintain system optimality. Constellations with phased deployment,… (more)

▼ Constellation reconfi guration consists of transforming an initial constellation of satellites into some final constellation of satellites to maintain system optimality. Constellations with phased deployment, changing mission requirements, or satellite failures would all benefi t from reconfi guration capability. The constellation reconfiguration problem can be broken into two broad sub-problems: constellation design and constellation transfer. Both are complicated and combinatorial in nature and require new, more efficient methods. Having reviewed existing constellation design frameworks, a new framework, the Elliptical Flower Constellations (EFCs), has been developed that offers improved performance over traditional methods. To assist in rapidly analyzing constellation designs, a new method for orbit propagation based on a sequential solution of Kepler's equation is presented. The constellation transfer problem requires an optimal assignment of satellites in the initial orbit to slots in the final orbit based on optimal orbit transfers between them. A new method for approximately solving the optimal two-impulse orbit transfer with fixed end-points, the so-called minimum Delta v Lambert's problem, is developed that requires the solution of a 4th order polynomial, as opposed to the 6th or higher order polynomials or iterative techniques of existing methods. The recently developed Learning Approach to sampling optimization is applied to the particular problem of general orbit transfer between two generic orbits, with several enhancements specifi c to this problem that improve its performance. The constellation transfer problem is then posed as a Linear Assignment Problem and solved using the auction algorithm once the orbit transfers have been computed. Constellations designed for global navigation satellite systems and for global communications demonstrate signifi cant improvements through the use of the EFC framework over existing methods. An end-to-end example of constellation recon figuration for a constellation with changing regional coverage requirements shows the effectiveness of the constellation transfer methods. Advisors/Committee Members: Junkins, John L. (advisor), Mortari, Daniele (advisor), Hurtado, John E. (committee member), Rojas, Maurice (committee member).

Subjects/Keywords: constellation design; constellation reconfiguration; satellite constellation; orbit design; Kepler's equation

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APA (6^th Edition):

Davis, J. J. (2011). Constellation Reconfiguration: Tools and Analysis. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8325

Chicago Manual of Style (16^th Edition):

Davis, Jeremy John. “Constellation Reconfiguration: Tools and Analysis.” 2011. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8325.

MLA Handbook (7^th Edition):

Davis, Jeremy John. “Constellation Reconfiguration: Tools and Analysis.” 2011. Web. 25 Feb 2021.

Vancouver:

Davis JJ. Constellation Reconfiguration: Tools and Analysis. [Internet] [Doctoral dissertation]. Texas A&M University; 2011. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8325.

Council of Science Editors:

Davis JJ. Constellation Reconfiguration: Tools and Analysis. [Doctoral Dissertation]. Texas A&M University; 2011. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8325

23. Harris, Matthew Wade. Extremal Fields and Neighboring Optimal Control of Constrained Systems.

Degree: MS, Aerospace Engineering, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8748

► This work provides first and second-order expressions to approximate neighboring solutions to the m-point boundary value problem. Multi-point problems arise in optimal control because of… (more)

Subjects/Keywords: extremal field; neighboring optimal control

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APA (6^th Edition):

Harris, M. W. (2012). Extremal Fields and Neighboring Optimal Control of Constrained Systems. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8748

Chicago Manual of Style (16^th Edition):

Harris, Matthew Wade. “Extremal Fields and Neighboring Optimal Control of Constrained Systems.” 2012. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8748.

MLA Handbook (7^th Edition):

Harris, Matthew Wade. “Extremal Fields and Neighboring Optimal Control of Constrained Systems.” 2012. Web. 25 Feb 2021.

Vancouver:

Harris MW. Extremal Fields and Neighboring Optimal Control of Constrained Systems. [Internet] [Masters thesis]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8748.

Council of Science Editors:

Harris MW. Extremal Fields and Neighboring Optimal Control of Constrained Systems. [Masters Thesis]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8748

24. Missel, Jonathan William. Active Space Debris Removal using Capture and Ejection.

Degree: PhD, Aerospace Engineering, 2013, Texas A&M University

URL: http://hdl.handle.net/1969.1/149391

► Low Earth Orbit is over-cluttered with rogue objects that threaten existing technological assets and interfere with allocating new ones. Traditional satellite missions are not efficient… (more)

Subjects/Keywords: Active; space; debris; removal; Sling-sat; sweeper

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APA (6^th Edition):

Missel, J. W. (2013). Active Space Debris Removal using Capture and Ejection. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/149391

Chicago Manual of Style (16^th Edition):

Missel, Jonathan William. “Active Space Debris Removal using Capture and Ejection.” 2013. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/149391.

MLA Handbook (7^th Edition):

Missel, Jonathan William. “Active Space Debris Removal using Capture and Ejection.” 2013. Web. 25 Feb 2021.

Vancouver:

Missel JW. Active Space Debris Removal using Capture and Ejection. [Internet] [Doctoral dissertation]. Texas A&M University; 2013. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/149391.

Council of Science Editors:

Missel JW. Active Space Debris Removal using Capture and Ejection. [Doctoral Dissertation]. Texas A&M University; 2013. Available from: http://hdl.handle.net/1969.1/149391

25. Aures-Cavalieri, Kurt Dale. Implementing Feedback Control on a Novel Proximity Operations Simulation Platform.

Degree: MS, Aerospace Engineering, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9406

► Recently, The Land, Air and Space Robotics (LASR) Laboratory has demonstrated a state-of-the-art proximity operations test bed that will revolutionize the concept of portable space… (more)

Subjects/Keywords: feedback control; simulation; space systems; robotics

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APA (6^th Edition):

Aures-Cavalieri, K. D. (2012). Implementing Feedback Control on a Novel Proximity Operations Simulation Platform. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9406

Chicago Manual of Style (16^th Edition):

Aures-Cavalieri, Kurt Dale. “Implementing Feedback Control on a Novel Proximity Operations Simulation Platform.” 2012. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9406.

MLA Handbook (7^th Edition):

Aures-Cavalieri, Kurt Dale. “Implementing Feedback Control on a Novel Proximity Operations Simulation Platform.” 2012. Web. 25 Feb 2021.

Vancouver:

Aures-Cavalieri KD. Implementing Feedback Control on a Novel Proximity Operations Simulation Platform. [Internet] [Masters thesis]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9406.

Council of Science Editors:

Aures-Cavalieri KD. Implementing Feedback Control on a Novel Proximity Operations Simulation Platform. [Masters Thesis]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9406

26. Flewelling, Brien Roy. 3D Multi-Field Multi-Scale Features From Range Data In Spacecraft Proximity Operations.

Degree: PhD, Aerospace Engineering, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11105

► A fundamental problem in spacecraft proximity operations is the determination of the 6 degree of freedom relative navigation solution between the observer reference frame and… (more)

▼ A fundamental problem in spacecraft proximity operations is the determination of the 6 degree of freedom relative navigation solution between the observer reference frame and a reference frame tied to a proximal body. For the most unconstrained case, the proximal body may be uncontrolled, and the observer spacecraft has no a priori information on the body. A spacecraft in this scenario must simultaneously map the generally poorly known body being observed, and safely navigate relative to it. Simultaneous localization and mapping(SLAM)is a difficult problem which has been the focus of research in recent years. The most promising approaches extract local features in 2D or 3D measurements and track them in subsequent observations by means of matching a descriptor. These methods exist for both active sensors such as Light Detection and Ranging(LIDAR) or laser RADAR(LADAR), and passive sensors such as CCD and CMOS camera systems. This dissertation presents a method for fusing time of flight(ToF) range data inherent to scanning LIDAR systems with the passive light field measurements of optical systems, extracting features which exploit information from each sensor, and solving the unique SLAM problem inherent to spacecraft proximity operations. Scale Space analysis is extended to unstructured 3D point clouds by means of an approximation to the Laplace Beltrami operator which computes the scale space on a manifold embedded in 3D object space using Gaussian convolutions based on a geodesic distance weighting. The construction of the scale space is shown to be equivalent to both the application of the diffusion equation to the surface data, as well as the surface evolution process which results from mean curvature flow. Geometric features are localized in regions of high spatial curvature or large diffusion displacements at multiple scales. The extracted interest points are associated with a local multi-field descriptor constructed from measured data in the object space. Defining features in object space instead of image space is shown to bean important step making the simultaneous consideration of co-registered texture and the associated geometry possible. These descriptors known as Multi-Field Diffusion Flow Signatures encode the shape, and multi-texture information of local neighborhoods in textured range data. Multi-Field Diffusion Flow Signatures display utility in difficult space scenarios including high contrast and saturating lighting conditions, bland and repeating textures, as well as non-Lambertian surfaces. The effectiveness and utility of Multi-Field Multi-Scale(MFMS) Features described by Multi-Field Diffusion Flow Signatures is evaluated using real data from proximity operation experiments performed at the Land Air and Space Robotics(LASR) Laboratory at Texas A&M University. Advisors/Committee Members: Junkins, John L. (advisor), Mortari, Daniele (advisor), Pollock, Tom (committee member), Amato, Nancy (committee member).

Subjects/Keywords: Scale Space; Image Processing; LIDAR; Range Sensing; Sensor Fusion; Feature Detection; Relative-Navigation; Vision

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APA (6^th Edition):

Flewelling, B. R. (2012). 3D Multi-Field Multi-Scale Features From Range Data In Spacecraft Proximity Operations. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11105

Chicago Manual of Style (16^th Edition):

Flewelling, Brien Roy. “3D Multi-Field Multi-Scale Features From Range Data In Spacecraft Proximity Operations.” 2012. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11105.

MLA Handbook (7^th Edition):

Flewelling, Brien Roy. “3D Multi-Field Multi-Scale Features From Range Data In Spacecraft Proximity Operations.” 2012. Web. 25 Feb 2021.

Vancouver:

Flewelling BR. 3D Multi-Field Multi-Scale Features From Range Data In Spacecraft Proximity Operations. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11105.

Council of Science Editors:

Flewelling BR. 3D Multi-Field Multi-Scale Features From Range Data In Spacecraft Proximity Operations. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11105

27. Biggers, Keith Edward. Inference-based Geometric Modeling for the Generation of Complex Cluttered Virtual Environments.

Degree: PhD, Computer Science, 2012, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9209

► As the use of simulation increases across many diff erent application domains, the need for high- fidelity three-dimensional virtual representations of real-world environments has never… (more)

▼ As the use of simulation increases across many diff erent application domains, the need for high- fidelity three-dimensional virtual representations of real-world environments has never been greater. This need has driven the research and development of both faster and easier methodologies for creating such representations. In this research, we present two diff erent inference-based geometric modeling techniques that support the automatic construction of complex cluttered environments. The fi rst method we present is a surface reconstruction-based approach that is capable of reconstructing solid models from a point cloud capture of a cluttered environment. Our algorithm is capable of identifying objects of interest amongst a cluttered scene, and reconstructing complete representations of these objects even in the presence of occluded surfaces. This approach incorporates a predictive modeling framework that uses a set of user provided models for prior knowledge, and applies this knowledge to the iterative identifi cation and construction process. Our approach uses a local to global construction process guided by rules for fi tting high quality surface patches obtained from these prior models. We demonstrate the application of this algorithm on several synthetic and real-world datasets containing heavy clutter and occlusion. The second method we present is a generative modeling-based approach that can construct a wide variety of diverse models based on user provided templates. This technique leverages an inference-based construction algorithm for developing solid models from these template objects. This algorithm samples and extracts surface patches from the input models, and develops a Petri net structure that is used by our algorithm for properly fitting these patches in a consistent fashion. Our approach uses this generated structure, along with a defi ned parameterization (either user-defi ned through a simple sketch-based interface or algorithmically de fined through various methods), to automatically construct objects of varying sizes and con figurations. These variations can include arbitrary articulation, and repetition and interchanging of parts sampled from the input models. Finally, we affim our motivation by showing an application of these two approaches. We demonstrate how the constructed environments can be easily used within a physically-based simulation, capable of supporting many diff erent application domains. Advisors/Committee Members: Keyser, John (advisor), Williams, Glen (advisor), Schaefer, Scott (committee member), Junkins, John (committee member).

Subjects/Keywords: Surface Reconstruction; Generative Modeling; Solid Modeling; Complex Cluttered Virtual Environments

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APA (6^th Edition):

Biggers, K. E. (2012). Inference-based Geometric Modeling for the Generation of Complex Cluttered Virtual Environments. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9209

Chicago Manual of Style (16^th Edition):

Biggers, Keith Edward. “Inference-based Geometric Modeling for the Generation of Complex Cluttered Virtual Environments.” 2012. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9209.

MLA Handbook (7^th Edition):

Biggers, Keith Edward. “Inference-based Geometric Modeling for the Generation of Complex Cluttered Virtual Environments.” 2012. Web. 25 Feb 2021.

Vancouver:

Biggers KE. Inference-based Geometric Modeling for the Generation of Complex Cluttered Virtual Environments. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9209.

Council of Science Editors:

Biggers KE. Inference-based Geometric Modeling for the Generation of Complex Cluttered Virtual Environments. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9209

28. Masher, Abhay Hiren. Control of Active Pendulum for Contact Dynamics Simulation.

Degree: MS, Aerospace Engineering, 2016, Texas A&M University

URL: http://hdl.handle.net/1969.1/158669

► Space proximity missions essentially need on the ground hardware in the loop (HIL) testing of sensors, algorithms, and actuators. Such testing would surpass that of… (more)

Subjects/Keywords: proximity operations; contact dynamics; nonlinear control; underactuated; cart-pole

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APA (6^th Edition):

Masher, A. H. (2016). Control of Active Pendulum for Contact Dynamics Simulation. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/158669

Chicago Manual of Style (16^th Edition):

Masher, Abhay Hiren. “Control of Active Pendulum for Contact Dynamics Simulation.” 2016. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/158669.

MLA Handbook (7^th Edition):

Masher, Abhay Hiren. “Control of Active Pendulum for Contact Dynamics Simulation.” 2016. Web. 25 Feb 2021.

Vancouver:

Masher AH. Control of Active Pendulum for Contact Dynamics Simulation. [Internet] [Masters thesis]. Texas A&M University; 2016. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/158669.

Council of Science Editors:

Masher AH. Control of Active Pendulum for Contact Dynamics Simulation. [Masters Thesis]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/158669

29. Kaushik, Arvind Shankar. A Statistical Comparison Between Gibbs and Herrick-Gibbs Orbit Determination Methods.

Degree: MS, Aerospace Engineering, 2016, Texas A&M University

URL: http://hdl.handle.net/1969.1/157747

► The detection, tracking, identification, and characterization (DTIC) of resident space objects (RSOs) is an important aspect of space situational awareness (SSA). Monitoring the space environment… (more)

Subjects/Keywords: Orbit Determination; Gibbs; Herrick-Gibbs; IOD; Space Situational Awareness

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APA (6^th Edition):

Kaushik, A. S. (2016). A Statistical Comparison Between Gibbs and Herrick-Gibbs Orbit Determination Methods. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/157747

Chicago Manual of Style (16^th Edition):

Kaushik, Arvind Shankar. “A Statistical Comparison Between Gibbs and Herrick-Gibbs Orbit Determination Methods.” 2016. Masters Thesis, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/157747.

MLA Handbook (7^th Edition):

Kaushik, Arvind Shankar. “A Statistical Comparison Between Gibbs and Herrick-Gibbs Orbit Determination Methods.” 2016. Web. 25 Feb 2021.

Vancouver:

Kaushik AS. A Statistical Comparison Between Gibbs and Herrick-Gibbs Orbit Determination Methods. [Internet] [Masters thesis]. Texas A&M University; 2016. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/157747.

Council of Science Editors:

Kaushik AS. A Statistical Comparison Between Gibbs and Herrick-Gibbs Orbit Determination Methods. [Masters Thesis]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/157747

30. Katake, Anup Bharat. Modeling, image processing and attitude estimation of high speed star sensors.

Degree: PhD, Aerospace Engineering, 2009, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-1018

► Attitude estimation and angular velocity estimation are the most critical components of a spacecraft's guidance, navigation and control. Usually, an array of tightlycoupled sensors (star… (more)

▼ Attitude estimation and angular velocity estimation are the most critical components of a spacecraft's guidance, navigation and control. Usually, an array of tightlycoupled sensors (star trackers, gyroscopes, sun sensors, magnetometers) is used to estimate these quantities. The cost (financial, mass, power, time, human resources) for the integration of these separate sub-systems is a major deterrent towards realizing the goal of smaller, cheaper and faster to launch spacecrafts/satellites. In this work, we present a novel stellar imaging system that is capable of estimating attitude and angular velocities at true update rates of greater than 100Hz, thereby eliminating the need for a separate star tracker and gyroscope sub-systems. High image acquisition rates necessitate short integration times and large optical apertures, thereby adding mass and volume to the sensor. The proposed high speed sensor overcomes these difficulties by employing light amplification technologies coupled with fiber optics. To better understand the performance of the sensor, an electro-optical model of the sensor system is developed which is then used to design a high-fidelity night sky image simulator. Novel star position estimation algorithms based on a two-dimensional Gaussian fitting to the star pixel intensity profiles are then presented. These algorithms are non-iterative, perform local background estimation in the vicinity of the star and lead to significant improvements in the star centroid determination. Further, a new attitude determination algorithm is developed that uses the inter-star angles of the identified stars as constraints to recompute the body measured vectors and provide a higher accuracy estimate of the attitude as compared to existing methods. The spectral response of the sensor is then used to develop a star catalog generation method that results in a compact on-board star catalog. Finally, the use of a fiber optic faceplate is proposed as an additional means of stray light mitigation for the system. This dissertation serves to validate the conceptual design of the high update rate star sensor through analysis, hardware design, algorithm development and experimental testing. Advisors/Committee Members: Junkins, John L (advisor), Mahapatra, Rabi (committee member), Mortari, Daniele (committee member), Pollock, Thomas (committee member).

Subjects/Keywords: star trackers; stellar gyroscope; recentroiding; attitude determination; image intensification

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APA (6^th Edition):

Katake, A. B. (2009). Modeling, image processing and attitude estimation of high speed star sensors. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-1018

Chicago Manual of Style (16^th Edition):

Katake, Anup Bharat. “Modeling, image processing and attitude estimation of high speed star sensors.” 2009. Doctoral Dissertation, Texas A&M University. Accessed February 25, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-1018.

MLA Handbook (7^th Edition):

Katake, Anup Bharat. “Modeling, image processing and attitude estimation of high speed star sensors.” 2009. Web. 25 Feb 2021.

Vancouver:

Katake AB. Modeling, image processing and attitude estimation of high speed star sensors. [Internet] [Doctoral dissertation]. Texas A&M University; 2009. [cited 2021 Feb 25]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1018.

Council of Science Editors:

Katake AB. Modeling, image processing and attitude estimation of high speed star sensors. [Doctoral Dissertation]. Texas A&M University; 2009. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1018

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