+publisher:"Georgia Tech" +contributor:("Tsiotras, Panagiotis")

Georgia Tech

1. Zhang, Qifan. Learning Nash equilibria in zero-sum stochastic games via entropy-regularized policy approximation.

Degree: MS, Computer Science, 2020, Georgia Tech

► In this thesis, we explore the use of policy approximation for reducing the computational cost of learning Nash Equilibria in Multi-Agent Reinforcement Learning. Existing multi-agent… (more)

Subjects/Keywords: Reinforcement learning; Game theory; Nash equilibrium

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APA (6^th Edition):

Zhang, Q. (2020). Learning Nash equilibria in zero-sum stochastic games via entropy-regularized policy approximation. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/63651

Chicago Manual of Style (16^th Edition):

Zhang, Qifan. “Learning Nash equilibria in zero-sum stochastic games via entropy-regularized policy approximation.” 2020. Masters Thesis, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/63651.

MLA Handbook (7^th Edition):

Zhang, Qifan. “Learning Nash equilibria in zero-sum stochastic games via entropy-regularized policy approximation.” 2020. Web. 17 Apr 2021.

Vancouver:

Zhang Q. Learning Nash equilibria in zero-sum stochastic games via entropy-regularized policy approximation. [Internet] [Masters thesis]. Georgia Tech; 2020. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/63651.

Council of Science Editors:

Zhang Q. Learning Nash equilibria in zero-sum stochastic games via entropy-regularized policy approximation. [Masters Thesis]. Georgia Tech; 2020. Available from: http://hdl.handle.net/1853/63651

Georgia Tech

2. Choi, Su Yeon. Automatic mass balancing system for the 5-DOF spacecraft simulator.

Degree: MS, Aerospace Engineering, 2016, Georgia Tech

URL: http://hdl.handle.net/1853/55658

► Spacecraft simulators are widely used to validate spacecraft attitude determination and control techniques. The Autonomous Spacecraft Testing of Robotic Operations in Space (ASTROS) facility at… (more)

Subjects/Keywords: Balancing system; Control; PID; EKF; Spacecraft

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APA (6^th Edition):

Choi, S. Y. (2016). Automatic mass balancing system for the 5-DOF spacecraft simulator. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/55658

Chicago Manual of Style (16^th Edition):

Choi, Su Yeon. “Automatic mass balancing system for the 5-DOF spacecraft simulator.” 2016. Masters Thesis, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/55658.

MLA Handbook (7^th Edition):

Choi, Su Yeon. “Automatic mass balancing system for the 5-DOF spacecraft simulator.” 2016. Web. 17 Apr 2021.

Vancouver:

Choi SY. Automatic mass balancing system for the 5-DOF spacecraft simulator. [Internet] [Masters thesis]. Georgia Tech; 2016. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/55658.

Council of Science Editors:

Choi SY. Automatic mass balancing system for the 5-DOF spacecraft simulator. [Masters Thesis]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/55658

3. Watts, Robert Michael. Development and evaluation of an automated path planning aid.

Degree: MS, Aerospace Engineering, 2010, Georgia Tech

URL: http://hdl.handle.net/1853/33839

► In the event of an onboard emergency, air transport pilots are remarkably adept at safely landing their aircraft. However, the tasks of selecting an alternate… (more)

▼ In the event of an onboard emergency, air transport pilots are remarkably adept at safely landing their aircraft. However, the tasks of selecting an alternate landing site and developing a safe path to land are very difficult in the high workload, high stress environment of a cockpit during an emergency. The purpose of this research was to develop an automated path planning aid which would assist the pilot in the completion of these tasks. A prototype was developed to test this concept experimentally. The experiment was also intended to gather further information about how pilots think about and accomplish this task as well as the best ways to assist them. In order to better understand the priorities and processes pilots use when dealing with emergency planning, a survey of airline pilots was conducted. The results of this survey highlighted the fact that each emergency is unique and has its own set of factors which are critically important. One factor which is important in many emergencies is the need to land quickly. The survey responses indicated that one of the most important characteristics of a useful tool is that it should provide pertinent information in an easy to use manner, and should not divert too much attention from their other tasks. A number of design goals drove the development of the prototype aid. First, the aid was to work within current aircraft, without requiring substantial redesign on the cockpit. Second, the aid was to help improve pilots' performance without increasing their workload. Finally, the aid was designed to assist pilots in obtaining and processing critical information which influences the site selection and path development tasks. One variation of the aid included a filter dial which allowed pilots to quickly reduce the number of options considered, another variation of the aid did not include such a dial. These two variations of the aid were tested in order to assess the impact of the addition of the filter dial to the system. Though many of the results did not prove to be statistically significant, they suggest that the addition of a filter dial improved the quality of the selected landing site; however, it also increased the time required for the selection. The results were obtained in both familiar and unfamiliar emergencies. The dial was shown to improve the time to complete the task in the case of unfamiliar emergencies. The experiment also compared an optimal ranking system to a non-optimal system, for which results showed no significant difference between the two. This may imply that while pilots did not tend to over rely on the ranking system, under-reliance may need to be addressed by training and a better understanding of the factors which impact the rankings. The participants found that the aid facilitates quick and easy access to critical information. The aid was also useful for processing this information by filtering out options which were inappropriate for a given scenario through the use of the filter dial. The participants also made… Advisors/Committee Members: Johnson, Eric (Committee Chair), Feigh, Karen (Committee Member), Pritchett, Amy (Committee Member), Tsiotras, Panagiotis (Committee Member).

Subjects/Keywords: In-flight emergency; Airplane cockpit design; Cockpit aid; Aerospace human factors; Decision aid; Landing aids (Aeronautics); Trajectory optimization

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APA (6^th Edition):

Watts, R. M. (2010). Development and evaluation of an automated path planning aid. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/33839

Chicago Manual of Style (16^th Edition):

Watts, Robert Michael. “Development and evaluation of an automated path planning aid.” 2010. Masters Thesis, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/33839.

MLA Handbook (7^th Edition):

Watts, Robert Michael. “Development and evaluation of an automated path planning aid.” 2010. Web. 17 Apr 2021.

Vancouver:

Watts RM. Development and evaluation of an automated path planning aid. [Internet] [Masters thesis]. Georgia Tech; 2010. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/33839.

Council of Science Editors:

Watts RM. Development and evaluation of an automated path planning aid. [Masters Thesis]. Georgia Tech; 2010. Available from: http://hdl.handle.net/1853/33839

4. Brewer, John M. Partial attitude synchronization of underactuated spacecraft systems.

Degree: MS, Aerospace Engineering, 2016, Georgia Tech

URL: http://hdl.handle.net/1853/56375

► Numerous works have investigated problems concerning the complete attitude consensus of multi-spacecraft systems as well as the attitude control of an underactuated spacecraft, where only… (more)

Subjects/Keywords: Attitude control; Cooperative control; Consensus; Decentralized control; Spacecraft control; Stabilization; Synchronization; Underactuated spacecraft

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APA (6^th Edition):

Brewer, J. M. (2016). Partial attitude synchronization of underactuated spacecraft systems. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/56375

Chicago Manual of Style (16^th Edition):

Brewer, John M. “Partial attitude synchronization of underactuated spacecraft systems.” 2016. Masters Thesis, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/56375.

MLA Handbook (7^th Edition):

Brewer, John M. “Partial attitude synchronization of underactuated spacecraft systems.” 2016. Web. 17 Apr 2021.

Vancouver:

Brewer JM. Partial attitude synchronization of underactuated spacecraft systems. [Internet] [Masters thesis]. Georgia Tech; 2016. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/56375.

Council of Science Editors:

Brewer JM. Partial attitude synchronization of underactuated spacecraft systems. [Masters Thesis]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/56375

Georgia Tech

5. Okamoto, Kazuhide. Optimal covariance steering: Theory and its application to autonomous driving.

Degree: PhD, Aerospace Engineering, 2019, Georgia Tech

URL: http://hdl.handle.net/1853/62260

► Optimal control under uncertainty has been one of the central research topics in the control community for decades. While a number of theories have been… (more)

▼ Optimal control under uncertainty has been one of the central research topics in the control community for decades. While a number of theories have been developed to control a single state from an initial state to a target state, in some situations, it is preferable to simultaneously compute control commands for multiple states that start from an initial distribution and converge to a target distribution. This dissertation aims to develop a stochastic optimal control theory that, in addition to the mean, explicitly steers the state covariance. Specifically, we focus on the control of linear time-varying (LTV) systems with additive Gaussian noise. The task is to steer a Gaussian-distributed initial system state distribution to a target Gaussian distribution, while minimizing a state and control expectation-dependent quadratic cost under probabilistic state constraints. Notice that, in such systems, the system state keeps being Gaussian distributed. Because Gaussian distributions can be fully described by the first two moments, the proposed optimal covariance steering (OCS) theory allows us to control the whole distribution of the state and quantify the effect of uncertainty without conducting Monte-Carlo simulations. We propose to use a control policy that is an affine function of filtered disturbances, which utilizes the results of convex optimization theory and efficiently finds the solution. After the OCS theory for LTV systems is introduced, we extend the theory to vehicle path planning problems. While several path planning algorithms have been proposed, many of them have dealt with deterministic dynamics or stochastic dynamics with open-loop un- certainty, i.e., the uncertainty of the system state is not controlled and, typically, increases with time due to exogenous disturbances, which may lead to the design of potentially conservative nominal paths. A typical approach to deal with disturbances is to use a lower-level local feedback controller after the nominal path is computed. This unidirectional dependence of the feedback controller on the path planner makes the nominal path unnecessarily conservative. The path-planning approach we develop based on the OCS theory computes the nominal path based on the closed-loop evolution of the system uncertainty by simultaneously optimizing the feedforward and feedback control commands. We validate the performance using numerical simulations with single and multiple vehicle path planning problems. Furthermore, we introduce an optimal covariance steering controller for linear systems with input hard constraints. As many real-world systems have input constraints (e.g., air- craft and spacecraft have minimum/maximum thrust), this problem formulation will allow us to deal with realistic scenarios. In order to incorporate input hard constraints in the OCS theory framework, we use element-wise saturation functions and limit the effect of disturbance to the control commands. We prove that this problem formulation leads to a convex programming problem and demonstrate the… Advisors/Committee Members: Tsiotras, Panagiotis (advisor), Clarke, Jahn-Paul (committee member), Chernova, Sonia (committee member), Rogers, Jonathan (committee member), Chen, Yongxin (committee member).

Subjects/Keywords: Stochastic control; Optimal control; Model predictive control; Vehicle path planning

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APA (6^th Edition):

Okamoto, K. (2019). Optimal covariance steering: Theory and its application to autonomous driving. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/62260

Chicago Manual of Style (16^th Edition):

Okamoto, Kazuhide. “Optimal covariance steering: Theory and its application to autonomous driving.” 2019. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/62260.

MLA Handbook (7^th Edition):

Okamoto, Kazuhide. “Optimal covariance steering: Theory and its application to autonomous driving.” 2019. Web. 17 Apr 2021.

Vancouver:

Okamoto K. Optimal covariance steering: Theory and its application to autonomous driving. [Internet] [Doctoral dissertation]. Georgia Tech; 2019. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/62260.

Council of Science Editors:

Okamoto K. Optimal covariance steering: Theory and its application to autonomous driving. [Doctoral Dissertation]. Georgia Tech; 2019. Available from: http://hdl.handle.net/1853/62260

Georgia Tech

6. Nakamura, Takuma. Multiple-hypothesis vision-based landing autonomy.

Degree: PhD, Aerospace Engineering, 2018, Georgia Tech

URL: http://hdl.handle.net/1853/62195

► Unmanned aerial vehicles (UAVs) need humans in the mission loop for many tasks, and landing is one of the tasks that typically involves a human… (more)

▼ Unmanned aerial vehicles (UAVs) need humans in the mission loop for many tasks, and landing is one of the tasks that typically involves a human pilot. This is because of the complexity of a maneuver itself and flight-critical factors such as recognition of a landing zone, collision avoidance, assessment of landing sites, and decision to abort the maneuver. Another critical aspect to be considered is the reliance of UAVs on GPS (global positioning system). A GPS system is not a reliable solution for landing in some scenarios (e.g. delivering a package in an urban city, and a surveillance UAV repatriating a home ship with the jammed signals), and a landing solely based on a GPS extremely decreases the UAV operation envelope. Vision is promising to achieve fully autonomous landing because it is a rich-sensing, light, affordable device that functions without any external resource. Although vision is a powerful tool for autonomous landing, the use of vision for state estimation requires extensive consideration. Firstly, vision-based landing faces a problem of occlusion. The target detected at a high altitude would be lost at certain altitudes while a vehicle descends; however, a small visual target can not be recognized at high altitude. Second, standard filtering methods such as extended Kalman filter (EKF) face difficulty due to the complex dynamics of the measurement error created due to the discrete pixel space, conversion from the pixel to physical units, the complex camera model, and complexity of detection algorithms. The vision sensor produces an unfixed number of measurements with each image, and the measurements may include false positives. Plus, the estimation system is excessively tasked in realistic conditions. The landing site would be moving, tilted, or close to an obstacle. The available landing location may not be limited to one. In addition to assessing these statuses, understanding the confidence of the estimations is also the tasks of the vision, and the decisions to initiate, continue, and abort the mission are made based on the estimated states and confidence. The system that handles those issues and consistently produces the navigation solution while a vehicle lands eliminates one of the limitations of the autonomous UAV operation. This thesis presents a novel state estimation system for UAV landing. In this system, vision data is used to both estimate the state of the vehicle and map the state of the landing target (position, velocity, and attitude) within the framework of simultaneous localization and mapping (SLAM). Using the SLAM framework, the system becomes resilient to a loss of GPS and other sensor failures. A novel vision algorithm that detects a portion of the marker is developed, and the stochastic properties of the algorithm are studied. This algorithm extends the detectable range of the vision system for any known marker. However, this vision algorithm produces highly nonlinear, non-Gaussian, and multi-modal error distribution, and a naive implementation of filters would not accurately… Advisors/Committee Members: Johnson, Eric (advisor), Tsiotras, Panagiotis (advisor), Feron, Eric (committee member), Vela, Patricio (committee member), Hays, James (committee member).

Subjects/Keywords: Sensor fusion; Kalman filter; Particle filter; SLAM; Computer vision

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APA (6^th Edition):

Nakamura, T. (2018). Multiple-hypothesis vision-based landing autonomy. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/62195

Chicago Manual of Style (16^th Edition):

Nakamura, Takuma. “Multiple-hypothesis vision-based landing autonomy.” 2018. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/62195.

MLA Handbook (7^th Edition):

Nakamura, Takuma. “Multiple-hypothesis vision-based landing autonomy.” 2018. Web. 17 Apr 2021.

Vancouver:

Nakamura T. Multiple-hypothesis vision-based landing autonomy. [Internet] [Doctoral dissertation]. Georgia Tech; 2018. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/62195.

Council of Science Editors:

Nakamura T. Multiple-hypothesis vision-based landing autonomy. [Doctoral Dissertation]. Georgia Tech; 2018. Available from: http://hdl.handle.net/1853/62195

Georgia Tech

7. You, Changxi. Autonomous aggressive driving: theory & experiments.

Degree: PhD, Department, 2020, Georgia Tech

URL: http://hdl.handle.net/1853/62872

► Autonomous vehicles represent a major trend in future intelligent transportation systems. In order to develop autonomous vehicles, this dissertation intends to understand expert driving maneuvers… (more)

▼ Autonomous vehicles represent a major trend in future intelligent transportation systems. In order to develop autonomous vehicles, this dissertation intends to understand expert driving maneuvers in different scenarios such as highway overtaking and off-road rally racing, which are referred to as ``aggressive'' driving in the context of this dissertation. By mimicking expert driving styles, one expects to be able to improve the vehicle's active safety and traffic efficiency in the development of autonomous vehicles. This dissertation starts from the system modeling, namely, driver modeling, vehicle modeling and traffic system modeling, for which we implement different Kalman type filters for nonlinear parameter estimation using experimental data. We then focus on the optimal decision making, path planning and control design problems for highway overtaking and off-road autonomous rally racing, respectively. We propose to use a stochastic MDP for highway traffic modeling. The new concept of ``dynamic cell'' is introduced to dynamically extract the essential state of the traffic according to different vehicle velocities, driver intents (i.e., lane-switching, braking, etc.) and sizes of the surrounding vehicles (i.e., truck, sedan, etc.). This allows us to solve the (inverse) reinforcement learning problem efficiently since the dimensionality of the state space can be maintained in a manageable level. New path planning algorithms using Bezier curves are proposed to generate everywhere 𝐶2 continuous curvature-constrained paths for highway real-time lane-switching. We demonstrate expert overtaking maneuver by implementing the proposed decision making, path planning and control algorithms on an in-house developed traffic simulator. Based on the trajectory learning result, we model high-speed cornering with a segment of steady-state cornering for off-road rally racing. We then propose a geometry-based trajectory planning algorithm using the vehicle's differential flatness. This approach avoids solving optimal control problems on-the-fly, while guaranteeing good racing performance in off-road racing. Advisors/Committee Members: Tsiotras, Panagiotis (advisor), Feron, Eric Marie J. (committee member), Feigh, Karen (committee member), Boots, Byron (committee member), Coogan, Samuel (committee member), names.

Subjects/Keywords: Autonomous vehicle path; Path planning; System identification; Decision making; Overtaking; Rally racing

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APA (6^th Edition):

You, C. (2020). Autonomous aggressive driving: theory & experiments. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/62872

Chicago Manual of Style (16^th Edition):

You, Changxi. “Autonomous aggressive driving: theory & experiments.” 2020. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/62872.

MLA Handbook (7^th Edition):

You, Changxi. “Autonomous aggressive driving: theory & experiments.” 2020. Web. 17 Apr 2021.

Vancouver:

You C. Autonomous aggressive driving: theory & experiments. [Internet] [Doctoral dissertation]. Georgia Tech; 2020. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/62872.

Council of Science Editors:

You C. Autonomous aggressive driving: theory & experiments. [Doctoral Dissertation]. Georgia Tech; 2020. Available from: http://hdl.handle.net/1853/62872

Georgia Tech

8. Park, Sang Gyun. Optimal control based method for design and analysis of continuous descent arrivals.

Degree: PhD, Aerospace Engineering, 2014, Georgia Tech

URL: http://hdl.handle.net/1853/53005

► Continuous Descent Arrival (CDA) is a procedure where aircraft descend, at or near idle thrust, from their cruise altitude to their Final Approach Fix without… (more)

▼ Continuous Descent Arrival (CDA) is a procedure where aircraft descend, at or near idle thrust, from their cruise altitude to their Final Approach Fix without leveling off. By eliminating inefficient leveling off at low altitude, CDA provides benefits such as fuel savings, flight time savings, and the significant noise reduction near airports, but the usage of CDAs has been limited in low traffic condition due to difficulty in the separation management. For the successful CDA without degradation of the runway throughput, air traffic controllers should know the performance bound of the CDA trajectory and control the time of arrival for each aircraft, which is interpreted as Required Time of Arrival (RTA) from the aircraft standpoint. This thesis proposes a novel trajectory optimization methodology to meet RTA constraint. The CDA trajectory optimization problem in the flight management system is modeled as a path constrained optimal control problem of switched dynamical system. A sequential method that performs mode sequence estimation and parameter optimization, sequentially, is proposed to solve this problem. By analyzing the relaxed optimal solution with simplified dynamics, a computationally efficient algorithm to find the optimal switching structure is proposed and applied for the mode sequence estimation. This thesis also proposes a performance-bound analysis methodology using optimal control techniques to help controllers make a feasible schedule for CDA operations at a meter fix. The feasible time range analysis for a wide variety of aircraft is performed by using the proposed methodology. Based on the analysis result, a single flight time strategy is proposed for the application of CDA in high traffic conditions. The simulation with real traffic data has been shown that the single flight time strategy, combined with the proposed fixed RTA trajectory optimization, guarantees the conflict free CDA operation. Advisors/Committee Members: Clarke, John-Paul B. (advisor), Feron, Eric (committee member), Tsiotras, Panagiotis (committee member), Prasad, J. V. R. (committee member), Egerstedt, Magnus (committee member).

Subjects/Keywords: Continuous descent arrival; Optimal control; Hybrid system; Trajectory optimization; Flight management system

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APA (6^th Edition):

Park, S. G. (2014). Optimal control based method for design and analysis of continuous descent arrivals. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53005

Chicago Manual of Style (16^th Edition):

Park, Sang Gyun. “Optimal control based method for design and analysis of continuous descent arrivals.” 2014. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/53005.

MLA Handbook (7^th Edition):

Park, Sang Gyun. “Optimal control based method for design and analysis of continuous descent arrivals.” 2014. Web. 17 Apr 2021.

Vancouver:

Park SG. Optimal control based method for design and analysis of continuous descent arrivals. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/53005.

Council of Science Editors:

Park SG. Optimal control based method for design and analysis of continuous descent arrivals. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/53005

Georgia Tech

9. Boidot, Emmanuel. Ambush games in discrete and continuous environments.

Degree: PhD, Aerospace Engineering, 2017, Georgia Tech

URL: http://hdl.handle.net/1853/59244

► We consider an autonomous navigation problem, whereby a traveler aims at traversing an environment in which an adversary sets an ambush. A two players zero-… (more)

▼ We consider an autonomous navigation problem, whereby a traveler aims at traversing an environment in which an adversary sets an ambush. A two players zero- sum game is introduced, describing the initial strategy of the traveler and the ambusher based on a description of the environment and the traveler initial location and desired goal. The process is single-step in the sense that agents do not reevaluate their strategy after the traveler has started moving. Players’ strategies are computed as probabilistic path distributions, a realization of which is the path chosen by the traveler and the ambush location chosen by the ambusher. A parallel is drawn between the discrete problem, where the traveler moves on a network, and the continuous problem, where the traveler moves in a compact subset of R2. Analytical optimal policies are derived. Assumptions from the Minimal Cut - Maximal Flow literature for continuous domains are used. The optimal value of the game is shown to be related to the maximum flow on the environment for sub-classes of games where the reward function for the ambusher is uniform. This proof is detailed in the discrete and continuous setups. In order to relax the assumptions for the computation of the players’ optimal strategies, a sampling-based approach is proposed, inspired by re- cent sampling-based motion planning techniques. Given a uniform reward function for the ambusher, optimal strategies of the sampled ambush game are proven to converge to the optimal strategy of the continuous ambush game under some sampling and connectivity constraints. A linear program is introduced that allows for the computation of optimal policies. The sampling-based approach is more general in the sense that it is compatible with constrained motion primitives for the traveler and non-uniform reward functions for the ambusher. The sampling-based game is used to create example applications for situ- ations where no analytic solution of the Continuous Ambush Game have been identified.This leads to more interesting games, applicable to real-world robots using modern motion planning algorithms. Examples of such games are setups where the traveler’s motion satis- fies Dubins’ kinematic constraints and setups where the reach of the ambusher is dependent on the speed of the traveler. Advisors/Committee Members: Feron, Eric (advisor), Tsiotras, Panagiotis (committee member), Clarke, John-Paul (committee member), Johnson, Eric (committee member), Coogan, Samuel (committee member).

Subjects/Keywords: Ambush games; Game theory; Motion planning; Continuous flow theory; Sampling-based motion planning

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APA (6^th Edition):

Boidot, E. (2017). Ambush games in discrete and continuous environments. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59244

Chicago Manual of Style (16^th Edition):

Boidot, Emmanuel. “Ambush games in discrete and continuous environments.” 2017. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/59244.

MLA Handbook (7^th Edition):

Boidot, Emmanuel. “Ambush games in discrete and continuous environments.” 2017. Web. 17 Apr 2021.

Vancouver:

Boidot E. Ambush games in discrete and continuous environments. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/59244.

Council of Science Editors:

Boidot E. Ambush games in discrete and continuous environments. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/59244

Georgia Tech

10. Exarchos, Ioannis. Stochastic optimal control - a forward and backward sampling approach.

Degree: PhD, Aerospace Engineering, 2017, Georgia Tech

URL: http://hdl.handle.net/1853/59263

► Stochastic optimal control has seen significant recent development, motivated by its success in a plethora of engineering applications, such as autonomous systems, robotics, neuroscience, and… (more)

▼ Stochastic optimal control has seen significant recent development, motivated by its success in a plethora of engineering applications, such as autonomous systems, robotics, neuroscience, and financial engineering. Despite the many theoretical and algorithmic advancements that made such a success possible, several obstacles remain; most notable are (i) the mitigation of the curse of dimensionality inherent in optimal control problems, (ii) the design of efficient algorithms that allow for fast, online computation, and (iii) the expansion of the class of optimal control problems that can be addressed by algorithms in engineering practice. The aim of this dissertation is the development of a learning stochastic control framework which capitalizes on the innate relationship between certain nonlinear partial differential equations (PDEs) and forward and backward stochastic differential equations (FBSDEs), demonstrated by a nonlinear version of the Feynman-Kac lemma. By means of this lemma, we are able to obtain a probabilistic representation of the solution to the nonlinear Hamilton-Jacobi-Bellman PDE, expressed in form of a system of decoupled FBSDEs. This system of FBSDEs can then be simulated by employing linear regression techniques. We present a novel discretization scheme for FBSDEs, and enhance the resulting algorithm with importance sampling, thereby constructing an iterative scheme that is capable of learning the optimal control without an initial guess, even in systems with highly nonlinear, underactuated dynamics. The framework we develop within this dissertation addresses several classes of stochastic optimal control, such as L2, L1, risk sensitive control, as well as some classes of differential games, in both fixed-final-time as well as first-exit settings. Advisors/Committee Members: Tsiotras, Panagiotis (advisor), Theodorou, Evangelos A. (advisor), Haddad, Wassim M. (committee member), Zhou, Haomin (committee member), Popescu, Ionel (committee member).

Subjects/Keywords: Stochastic optimal control; Forward and backward stochastic differential equations

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

APA (6^th Edition):

Exarchos, I. (2017). Stochastic optimal control - a forward and backward sampling approach. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59263

Chicago Manual of Style (16^th Edition):

Exarchos, Ioannis. “Stochastic optimal control - a forward and backward sampling approach.” 2017. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/59263.

MLA Handbook (7^th Edition):

Exarchos, Ioannis. “Stochastic optimal control - a forward and backward sampling approach.” 2017. Web. 17 Apr 2021.

Vancouver:

Exarchos I. Stochastic optimal control - a forward and backward sampling approach. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/59263.

Council of Science Editors:

Exarchos I. Stochastic optimal control - a forward and backward sampling approach. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/59263

Georgia Tech

11. Brew, Julian. Using sample-based continuation techniques to efficiently compute subspace reachable sets and Pareto surfaces.

Degree: PhD, Aerospace Engineering, 2019, Georgia Tech

URL: http://hdl.handle.net/1853/62341

► For a given continuous-time dynamical system with control input constraints and prescribed state boundary conditions, one can compute the reachable set at a specified time… (more)

▼ For a given continuous-time dynamical system with control input constraints and prescribed state boundary conditions, one can compute the reachable set at a specified time horizon. Forward reachable sets contain all states that can be reached using a feasible control policy at the specified time horizon. Alternatively, backwards reachable sets contain all initial states that can reach the prescribed state boundary condition using a feasible control policy at the specified time horizon. The computation of reachable sets has been applied to many problems such as vehicle collision avoidance, operational safety planning, system capability demonstration, and even economic modeling and weather forecasting. However, computing reachable volumes for general nonlinear systems is very difficult to do both accurately and efficiently. The first contribution of this thesis investigates computational techniques for alleviating the curse of dimensionality by computing reachable sets on subspaces of the full state dimension and computing point solutions for the reachable set boundary. To compute these point solutions, optimal control problems are reduced to initial value problems using continuation methods and then solved. The sample-based continuation techniques are computationally efficient in that they are easily parallelizable. However, the distribution of samples on the reachable set boundary is not directly controlled. The second contribution presents necessary conditions for distributed computation convergence, as well as necessary conditions for curvature- or uniform coverage-based sampling methods. Solutions to multi-objective optimization problems are generally defined using a set of feasible solutions such that for any one objective to improve it is necessary for other objectives to degrade. This suggests there is a connection between the two fields with the potential of cross-fertilization of computational techniques and theory. The third contribution explores analytical connections between reachability theory and multi-objective optimization with investigation into properties, constraints, and special cases. Advisors/Committee Members: Lightsey, Edgar (advisor), Holzinger, Marcus (advisor), Schuet, Stefan (committee member), Tsiotras, Panagiotis (committee member), Rogers, Jonathan (committee member).

Subjects/Keywords: Optimal control; Reachability; Continuation

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APA (6^th Edition):

Brew, J. (2019). Using sample-based continuation techniques to efficiently compute subspace reachable sets and Pareto surfaces. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/62341

Chicago Manual of Style (16^th Edition):

Brew, Julian. “Using sample-based continuation techniques to efficiently compute subspace reachable sets and Pareto surfaces.” 2019. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/62341.

MLA Handbook (7^th Edition):

Brew, Julian. “Using sample-based continuation techniques to efficiently compute subspace reachable sets and Pareto surfaces.” 2019. Web. 17 Apr 2021.

Vancouver:

Brew J. Using sample-based continuation techniques to efficiently compute subspace reachable sets and Pareto surfaces. [Internet] [Doctoral dissertation]. Georgia Tech; 2019. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/62341.

Council of Science Editors:

Brew J. Using sample-based continuation techniques to efficiently compute subspace reachable sets and Pareto surfaces. [Doctoral Dissertation]. Georgia Tech; 2019. Available from: http://hdl.handle.net/1853/62341

Georgia Tech

12. Elinger, Jared. Information Theoretic Causality Measures For Parameter Estimation and System Identification.

Degree: PhD, Mechanical Engineering, 2020, Georgia Tech

URL: http://hdl.handle.net/1853/64101

► Constructing a model for a dynamic system from observed data is a complicated yet common problem for many engineered systems. This task, known as system… (more)

▼ Constructing a model for a dynamic system from observed data is a complicated yet common problem for many engineered systems. This task, known as system identification, is a necessary step in many fields of engineering as it is often used for system modeling, simulation and control design. Inaccurate system models can lead to poor simulation results, which will lead to poor real world performance. While linear systems have a set of developed identification techniques, methods for nonlinear systems are not as generalizable or robust. Parameter estimation is a subset of system identification where a model structure is selected (either through first principles creating a grey box model or if a pre-prescribed structure is used for a black box model) with a set of parameters corresponding to the model needing to be optimized. In the case of linear systems, the solution to the parameter estimation problem is a closed-form least squares solution; however, parameters of nonlinear systems must be solved for numerically, which is subject to well-known issues of the solution converging to a local extrema. Maximum Likelihood Estimation (MLE) is commonly used to optimize the nonlinear system parameter set by minimizing the least-squares error between the actual data and the candidate optimized model. This optimization can often converge to local extrema, especially in the case noise, exogenous disturbance, or when a relatively small number of data points is available when compared to the dimension of the optimization problem. A problem known as overfitting can occur when a more complex model than needed is considered, as potentially multiple high accuracy unique model fits can be found over the available training data that generalizes poorly to unseen data as the optimized model no longer matches the generative dynamics. Methods to determine the optimal parameter set to be both accurate and predictive are critical to creation of a high fidelity model; these techniques are frequently referred to as covariate selection or feature selection techniques. The recently proposed Causation Entropy Matrix (CEM) allows for identification of causal information flow within a system. This is of immediate usefulness to many system identification tasks when the exact or entire structure of the system is unknown and covariate selection is needed. The CEM provides a method for pre-optimization, data-based covariate selection to allow for reduction of the number of parameters included in the system optimization to improve MLE results. This work provides background on the Causation Entropy Matrix and its computation before providing multiple examples of application of the CEM to grey-box and black-box modeling problems. The effectiveness of the Causation Entropy Matrix is then compared to the current state of the art techniques of LASSO (least absolute shrinkage and selection operator) and elastic net. Next, a chapter is dedicated to the practical considerations needed for application of the CEM to real-world systems including but not limited to… Advisors/Committee Members: Rogers, Jonathan (advisor), Ferri, Aldo (committee member), Leamy, Michael (committee member), Hammond, Frank (committee member), Tsiotras, Panagiotis (committee member).

Subjects/Keywords: System Identification; Covariate Selection; Parameter Estimation; Feature Selection; Sparsity Identification; Maximum Likelihood Estimation; Nonlinear Systems; Overfitting

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APA (6^th Edition):

Elinger, J. (2020). Information Theoretic Causality Measures For Parameter Estimation and System Identification. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/64101

Chicago Manual of Style (16^th Edition):

Elinger, Jared. “Information Theoretic Causality Measures For Parameter Estimation and System Identification.” 2020. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/64101.

MLA Handbook (7^th Edition):

Elinger, Jared. “Information Theoretic Causality Measures For Parameter Estimation and System Identification.” 2020. Web. 17 Apr 2021.

Vancouver:

Elinger J. Information Theoretic Causality Measures For Parameter Estimation and System Identification. [Internet] [Doctoral dissertation]. Georgia Tech; 2020. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/64101.

Council of Science Editors:

Elinger J. Information Theoretic Causality Measures For Parameter Estimation and System Identification. [Doctoral Dissertation]. Georgia Tech; 2020. Available from: http://hdl.handle.net/1853/64101

13. Hauer, Florian M. Path-planning algorithms in high-dimensional spaces.

Degree: PhD, Aerospace Engineering, 2019, Georgia Tech

URL: http://hdl.handle.net/1853/61206

► In this thesis, we discuss the problem of path-planning in high-dimensional spaces. Large search spaces tend to lead to slow algorithms in order to find… (more)

Subjects/Keywords: Path-planning; RRT; Sampling-based; Algorithms; Completeness; Graph; Search

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APA (6^th Edition):

Hauer, F. M. (2019). Path-planning algorithms in high-dimensional spaces. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/61206

Chicago Manual of Style (16^th Edition):

Hauer, Florian M. “Path-planning algorithms in high-dimensional spaces.” 2019. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/61206.

MLA Handbook (7^th Edition):

Hauer, Florian M. “Path-planning algorithms in high-dimensional spaces.” 2019. Web. 17 Apr 2021.

Vancouver:

Hauer FM. Path-planning algorithms in high-dimensional spaces. [Internet] [Doctoral dissertation]. Georgia Tech; 2019. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/61206.

Council of Science Editors:

Hauer FM. Path-planning algorithms in high-dimensional spaces. [Doctoral Dissertation]. Georgia Tech; 2019. Available from: http://hdl.handle.net/1853/61206

14. Bentley, Jason A. Systematic process development by simultaneous modeling and optimization of simulated moving bed chromatography.

Degree: PhD, Chemical and Biomolecular Engineering, 2013, Georgia Tech

URL: http://hdl.handle.net/1853/47531

► Adsorption separation processes are extremely important to the chemical industry, especially in the manufacturing of food, pharmaceutical, and fine chemical products. This work addresses three… (more)

▼ Adsorption separation processes are extremely important to the chemical industry, especially in the manufacturing of food, pharmaceutical, and fine chemical products. This work addresses three main topics: first, systematic decision-making between rival gas phase adsorption processes for the same separation problem; second, process development for liquid phase simulated moving bed chromatography (SMB); third, accelerated startup for SMB units. All of the work in this thesis uses model-based optimization to answer complicated questions about process selection, process development, and control of transient operation. It is shown in this thesis that there is a trade-off between productivity and product recovery in the gaseous separation of enantiomers using SMB and pressure swing adsorption (PSA). These processes are considered as rivals for the same separation problem and it is found that each process has a particular advantage that may be exploited depending on the production goals and economics. The processes are compared on a fair basis of equal capitol investment and the same multi-objective optimization problem is solved with equal constraints on the operating parameters. Secondly, this thesis demonstrates by experiment a systematic algorithm for SMB process development that utilizes dynamic optimization, transient experimental data, and parameter estimation to arrive at optimal operating conditions for a new separation problem in a matter of hours. Comparatively, the conventional process development for SMB relies on careful system characterization using single-column experiments, and manual tuning of operating parameters, that may take days and weeks. The optimal operating conditions that are found by this new method ensure both high purity constraints and optimal productivity are satisfied. The proposed algorithm proceeds until the SMB process is optimized without manual tuning. In some case studies, it is shown with both linear and nonlinear isotherm systems that the optimal performance can be reached in only two changes of operating conditions following the proposed algorithm. Finally, it is shown experimentally that the startup time for a real SMB unit is significantly reduced by solving model-based startup optimization problems using the SMB model developed from the proposed algorithm. The startup acceleration with purity constraints is shown to be successful at reducing the startup time by about 44%, and it is confirmed that the product purities are maintained during the operation. Significant cost savings in terms of decreased processing time and increased average product concentration can be attained using a relatively simple startup acceleration strategy. Advisors/Committee Members: Kawajiri, Yoshiaki (Committee Chair), Koros, William (Committee Member), Realff, Matthew (Committee Member), Tsiotras, Panagiotis (Committee Member), Walton, Krista (Committee Member).

Subjects/Keywords: Simulated moving bed chromatography; Adsorption processes; Model selection; Parameter estimation; Numerical optimization; Transient process control; Adsorption; Separation (Technology); Chromatographic analysis

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APA (6^th Edition):

Bentley, J. A. (2013). Systematic process development by simultaneous modeling and optimization of simulated moving bed chromatography. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/47531

Chicago Manual of Style (16^th Edition):

Bentley, Jason A. “Systematic process development by simultaneous modeling and optimization of simulated moving bed chromatography.” 2013. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/47531.

MLA Handbook (7^th Edition):

Bentley, Jason A. “Systematic process development by simultaneous modeling and optimization of simulated moving bed chromatography.” 2013. Web. 17 Apr 2021.

Vancouver:

Bentley JA. Systematic process development by simultaneous modeling and optimization of simulated moving bed chromatography. [Internet] [Doctoral dissertation]. Georgia Tech; 2013. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/47531.

Council of Science Editors:

Bentley JA. Systematic process development by simultaneous modeling and optimization of simulated moving bed chromatography. [Doctoral Dissertation]. Georgia Tech; 2013. Available from: http://hdl.handle.net/1853/47531

15. Bakolas, Efstathios. Optimal steering for kinematic vehicles with applications to spatially distributed agents.

Degree: PhD, Aerospace Engineering, 2011, Georgia Tech

URL: http://hdl.handle.net/1853/42873

► The recent technological advances in the field of autonomous vehicles have resulted in a growing impetus for researchers to improve the current framework of mission… (more)

▼ The recent technological advances in the field of autonomous vehicles have resulted in a growing impetus for researchers to improve the current framework of mission planning and execution within both the military and civilian contexts. Many recent efforts towards this direction emphasize the importance of replacing the so-called monolithic paradigm, where a mission is planned, monitored, and controlled by a unique global decision maker, with a network centric paradigm, where the same mission related tasks are performed by networks of interacting decision makers (autonomous vehicles). The interest in applications involving teams of autonomous vehicles is expected to significantly grow in the near future as new paradigms for their use are constantly being proposed for a diverse spectrum of real world applications. One promising approach to extend available techniques for addressing problems involving a single autonomous vehicle to those involving teams of autonomous vehicles is to use the concept of Voronoi diagram as a means for reducing the complexity of the multi-vehicle problem. In particular, the Voronoi diagram provides a spatial partition of the environment the team of vehicles operate in, where each element of this partition is associated with a unique vehicle from the team. The partition induces, in turn, a graph abstraction of the operating space that is in a one-to-one correspondence with the network abstraction of the team of autonomous vehicles; a fact that can provide both conceptual and analytical advantages during mission planning and execution. In this dissertation, we propose the use of a new class of Voronoi-like partitioning schemes with respect to state-dependent proximity (pseudo-) metrics rather than the Euclidean distance or other generalized distance functions, which are typically used in the literature. An important nuance here is that, in contrast to the Euclidean distance, state-dependent metrics can succinctly capture system theoretic features of each vehicle from the team (e.g., vehicle kinematics), as well as the environment-vehicle interactions, which are induced, for example, by local winds/currents. We subsequently illustrate how the proposed concept of state-dependent Voronoi-like partition can induce local control schemes for problems involving networks of spatially distributed autonomous vehicles by examining different application scenarios. Advisors/Committee Members: Tsiotras Panagiotis (Committee Chair), Egerstedt Magnus (Committee Member), Feron Eric (Committee Member), Haddad Wassim (Committee Member), Shamma Jeff (Committee Member).

Subjects/Keywords: Autonomous agents; Optimal control; Nonholonomic systems; Voronoi diagrams; Path planning; Pursuit games; Guidance; Navigation; Engineering systems; Voronoi polygons; Guidance systems (Flight); Automatic control

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APA (6^th Edition):

Bakolas, E. (2011). Optimal steering for kinematic vehicles with applications to spatially distributed agents. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/42873

Chicago Manual of Style (16^th Edition):

Bakolas, Efstathios. “Optimal steering for kinematic vehicles with applications to spatially distributed agents.” 2011. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/42873.

MLA Handbook (7^th Edition):

Bakolas, Efstathios. “Optimal steering for kinematic vehicles with applications to spatially distributed agents.” 2011. Web. 17 Apr 2021.

Vancouver:

Bakolas E. Optimal steering for kinematic vehicles with applications to spatially distributed agents. [Internet] [Doctoral dissertation]. Georgia Tech; 2011. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/42873.

Council of Science Editors:

Bakolas E. Optimal steering for kinematic vehicles with applications to spatially distributed agents. [Doctoral Dissertation]. Georgia Tech; 2011. Available from: http://hdl.handle.net/1853/42873

16. Hui, Qing. Nonlinear dynamical systems and control for large-scale, hybrid, and network systems.

Degree: PhD, Aerospace Engineering, 2008, Georgia Tech

URL: http://hdl.handle.net/1853/24635

► In this dissertation, we present several main research thrusts involving thermodynamic stabilization via energy dissipating hybrid controllers and nonlinear control of network systems. Specifically, a… (more)

▼ In this dissertation, we present several main research thrusts involving thermodynamic stabilization via energy dissipating hybrid controllers and nonlinear control of network systems. Specifically, a novel class of fixed-order, energy-based hybrid controllers is presented as a means for achieving enhanced energy dissipation in Euler-Lagrange, lossless, and dissipative dynamical systems. These dynamic controllers combine a logical switching architecture with continuous dynamics to guarantee that the system plant energy is strictly decreasing across switching. In addition, we construct hybrid dynamic controllers that guarantee that the closed-loop system is consistent with basic thermodynamic principles. In particular, the existence of an entropy function for the closed-loop system is established that satisfies a hybrid Clausius-type inequality. Special cases of energy-based hybrid controllers involving state-dependent switching are described, and the framework is applied to aerospace system models. The overall framework demonstrates that energy-based hybrid resetting controllers provide an extremely efficient mechanism for dissipating energy in nonlinear dynamical systems. Next, we present finite-time coordination controllers for multiagent network systems. Recent technological advances in communications and computation have spurred a broad interest in autonomous, adaptable vehicle formations. Distributed decision-making for coordination of networks of dynamic agents addresses a broad area of applications including cooperative control of unmanned air vehicles, microsatellite clusters, mobile robotics, and congestion control in communication networks. In this part of the dissertation we focus on finite-time consensus protocols for networks of dynamic agents with undirected information flow. The proposed controller architectures are predicated on the recently developed notion of system thermodynamics resulting in thermodynamically consistent continuous controller architectures involving the exchange of information between agents that guarantee that the closed-loop dynamical network is consistent with basic thermodynamic principles. Advisors/Committee Members: Haddad, Wassim (Committee Chair), Feron, Eric (Committee Member), JVR, Prasad (Committee Member), Taylor, David (Committee Member), Tsiotras, Panagiotis (Committee Member).

Subjects/Keywords: Network systems; Stability theory; Cooperative control; Hybrid control; Consensus protocols; Nonlinear systems; Dynamical systems; Hybrid systems; Large-scale systems; Systems engineering; Nonlinear control theory; Lyapunov stability; Control theory; Large scale systems; Entropy; Thermodynamics

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APA (6^th Edition):

Hui, Q. (2008). Nonlinear dynamical systems and control for large-scale, hybrid, and network systems. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/24635

Chicago Manual of Style (16^th Edition):

Hui, Qing. “Nonlinear dynamical systems and control for large-scale, hybrid, and network systems.” 2008. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/24635.

MLA Handbook (7^th Edition):

Hui, Qing. “Nonlinear dynamical systems and control for large-scale, hybrid, and network systems.” 2008. Web. 17 Apr 2021.

Vancouver:

Hui Q. Nonlinear dynamical systems and control for large-scale, hybrid, and network systems. [Internet] [Doctoral dissertation]. Georgia Tech; 2008. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/24635.

Council of Science Editors:

Hui Q. Nonlinear dynamical systems and control for large-scale, hybrid, and network systems. [Doctoral Dissertation]. Georgia Tech; 2008. Available from: http://hdl.handle.net/1853/24635

17. Ta Huynh, Duy Nguyen. The roles of allocentric representations in autonomous local navigation.

Degree: PhD, Computer Science, 2015, Georgia Tech

URL: http://hdl.handle.net/1853/53489

► In this thesis, I study the computational advantages of the allocentric represen- tation as compared to the egocentric representation for autonomous local navigation. Whereas in… (more)

Subjects/Keywords: Allocentric; Egocentric; Autonomous navigation; SLAM; Obstacle avoidance; Model predictive control; Lie groups; Robotics

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APA (6^th Edition):

Ta Huynh, D. N. (2015). The roles of allocentric representations in autonomous local navigation. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53489

Chicago Manual of Style (16^th Edition):

Ta Huynh, Duy Nguyen. “The roles of allocentric representations in autonomous local navigation.” 2015. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/53489.

MLA Handbook (7^th Edition):

Ta Huynh, Duy Nguyen. “The roles of allocentric representations in autonomous local navigation.” 2015. Web. 17 Apr 2021.

Vancouver:

Ta Huynh DN. The roles of allocentric representations in autonomous local navigation. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/53489.

Council of Science Editors:

Ta Huynh DN. The roles of allocentric representations in autonomous local navigation. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53489

18. Kortenbruck, Julius. Tire model identification and development of a tire-road friction observer.

Degree: MS, Mechanical Engineering, 2019, Georgia Tech

URL: http://hdl.handle.net/1853/61809

► In order to improve vehicle safety systems and autonomous control of vehicles, the real time knowledge of tire forces and friction coefficient is desirable. The… (more)

▼ In order to improve vehicle safety systems and autonomous control of vehicles, the real time knowledge of tire forces and friction coefficient is desirable. The tire interaction with the road through the tire contact patch is the only means to control the movement of the vehicle. The goal of this thesis is to develop a nonlinear observer for estimation of the potential of the road friction coefficient during various driving maneuvers. Maneuvers will be performed by a nonlinear 14 degree of freedom vehicle model with independent suspension, which serves as a substitute for a physical vehicle. An Extended Kalman filter is chosen as the observer. Within the observer, the reference vehicle is represented by a nonlinear single-track model. The tire model used is a modified version of the widely known Pacejka Magic Formula tire model. To identify the parameters for the tire model, a gradient based minimization problem is solved to find the tire parameters such that the dynamic characteristics of the single-track model closely match those of the reference vehicle. Once the tire parameters are determined, a similar minimization problem is set up and solved to obtain the parameters for the Extended Kalman Filter. Parameters of the EKF are chosen such that the state estimation closely matches a reference measurement from the complex vehicle simulation model. The resulting observer shows good performance in estimating the friction coefficient during highly nonlinear maneuvers. Some maneuvers are performed that show the estimation of varying road conditions. The performance is governed by the quality of the - XIV - tire model. When the observer model shows poor performance in capturing the behavior of the reference vehicle, the estimation of the friction coefficient suffers. If the tire is operated in the linear region, the friction coefficient is harder to identify. Improvements in future work can be made by carefully selecting the maneuvers for identifying the tire model, such that a broader range of tire slip and normal load variations is reached. Advisors/Committee Members: Tsiotras, Panagiotis (advisor), Leamy, Michael (advisor), Ferri, Aldo A. (committee member), Sawodny, Oliver (committee member), Tarin, Cristina (committee member).

Subjects/Keywords: Pacejka; Friction observer; Tire model identification

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APA (6^th Edition):

Kortenbruck, J. (2019). Tire model identification and development of a tire-road friction observer. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/61809

Chicago Manual of Style (16^th Edition):

Kortenbruck, Julius. “Tire model identification and development of a tire-road friction observer.” 2019. Masters Thesis, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/61809.

MLA Handbook (7^th Edition):

Kortenbruck, Julius. “Tire model identification and development of a tire-road friction observer.” 2019. Web. 17 Apr 2021.

Vancouver:

Kortenbruck J. Tire model identification and development of a tire-road friction observer. [Internet] [Masters thesis]. Georgia Tech; 2019. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/61809.

Council of Science Editors:

Kortenbruck J. Tire model identification and development of a tire-road friction observer. [Masters Thesis]. Georgia Tech; 2019. Available from: http://hdl.handle.net/1853/61809

Georgia Tech

19. Christmann, Hans Claus. Communication-aware planning aid for single-operator multi-UAV teams in urban environments.

Degree: PhD, Aerospace Engineering, 2015, Georgia Tech

URL: http://hdl.handle.net/1853/53881

► With the achievement of autonomous flight for small unmanned aircraft, currently ongoing research is expanding the capabilities of systems utilizing such vehicles for various tasks.… (more)

▼ With the achievement of autonomous flight for small unmanned aircraft, currently ongoing research is expanding the capabilities of systems utilizing such vehicles for various tasks. This allows shifting the research focus from the individual systems to task execution benefits resulting from interaction and collaboration of several aircraft. Given that some available high-fidelity simulations do not yet support multi-vehicle scenarios, the presented work introduces a framework which allows several individual single-vehicle simulations to be combined into a larger multi-vehicle scenario with little to no special requirements towards the single-vehicle systems. The created multi-vehicle system offers real-time software-in-the-loop simulations of swarms of vehicles across multiple hosts and enables a single operator to command and control a swarm of unmanned aircraft beyond line-of-sight in geometrically correct two-dimensional cluttered environments through a multi-hop network of data-relaying intermediaries. This dissertation presents the main aspects of the developed system: the underlying software framework and application programming interface, the utilized inter- and intra-system communication architecture, the graphical user interface, and implemented algorithms and operator aid heuristics to support the management and placement of the vehicles. The effectiveness of the aid heuristics is validated through a human subject study which showed that the provided operator support systems significantly improve the operators' performance in a simulated first responder scenario. The presented software is released under the Apache License 2.0 and, where non-open-source parts are used, software packages with free academic licenses have been chosen – resulting in a framework that is completely free for academic research. Advisors/Committee Members: Johnson, Eric N. (advisor), Theodorou, Evangelos (advisor), Tsiotras, Panagiotis (committee member), Egerstedt, Magnus B. (committee member), Feigh, Karen M. (committee member), Feron, Eric M. (committee member).

Subjects/Keywords: UAV; UAS; Multi-vehicle; Simulation; Human-automation interaction; Urban environments; Multi-hop networking

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APA (6^th Edition):

Christmann, H. C. (2015). Communication-aware planning aid for single-operator multi-UAV teams in urban environments. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53881

Chicago Manual of Style (16^th Edition):

Christmann, Hans Claus. “Communication-aware planning aid for single-operator multi-UAV teams in urban environments.” 2015. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/53881.

MLA Handbook (7^th Edition):

Christmann, Hans Claus. “Communication-aware planning aid for single-operator multi-UAV teams in urban environments.” 2015. Web. 17 Apr 2021.

Vancouver:

Christmann HC. Communication-aware planning aid for single-operator multi-UAV teams in urban environments. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/53881.

Council of Science Editors:

Christmann HC. Communication-aware planning aid for single-operator multi-UAV teams in urban environments. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53881

Georgia Tech

20. Magree, Daniel Paul. Monocular vision-aided inertial navigation for unmanned aerial vehicles.

Degree: PhD, Aerospace Engineering, 2015, Georgia Tech

URL: http://hdl.handle.net/1853/53892

► The reliance of unmanned aerial vehicles (UAVs) on GPS and other external navigation aids has become a limiting factor for many missions. UAVs are now… (more)

▼ The reliance of unmanned aerial vehicles (UAVs) on GPS and other external navigation aids has become a limiting factor for many missions. UAVs are now physically able to fly in many enclosed or obstructed environments, due to the shrinking size and weight of electronics and other systems. These environments, such as urban canyons or enclosed areas, often degrade or deny external signals. Furthermore, many of the most valuable potential missions for UAVs are in hostile or disaster areas, where navigation infrastructure could be damaged, denied, or actively used against the vehicle. It is clear that developing alternative, independent, navigation techniques will increase the operating envelope of UAVs and make them more useful. This thesis presents work in the development of reliable monocular vision-aided inertial navigation for UAVs. The work focuses on developing a stable and accurate navigation solution in a variety of realistic conditions. First, a vision-aided inertial navigation algorithm is developed which assumes uncorrelated feature and vehicle states. Flight test results on a 80 kg UAV are presented, which demonstrate that it is possible to bound the horizontal drift with vision aiding. Additionally, a novel implementation method is developed for integration with a variety of navigation systems. Finally, a vision-aided navigation algorithm is derived within a Bierman-Thornton factored extended Kalman Filter (BTEKF) framework, using fully correlated vehicle and feature states. This algorithm shows improved consistency and accuracy by 2 to 3 orders of magnitude over the previous implementation, both in simulation and flight testing. Flight test results of the BTEKF on large (80 kg) and small (600 g) vehicles show accurate navigation over numerous tests. Advisors/Committee Members: Johnson, Eric N. (advisor), Theodorou, Evangelos (advisor), Dellaert, Frank (committee member), Costello, Mark (committee member), Prasad, J. V. R. (committee member), Tsiotras, Panagiotis (committee member).

Subjects/Keywords: Visual navigation; Filtering; Extended Kalman filter; Factorization methods; Unmanned aerial vehicles

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APA (6^th Edition):

Magree, D. P. (2015). Monocular vision-aided inertial navigation for unmanned aerial vehicles. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53892

Chicago Manual of Style (16^th Edition):

Magree, Daniel Paul. “Monocular vision-aided inertial navigation for unmanned aerial vehicles.” 2015. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/53892.

MLA Handbook (7^th Edition):

Magree, Daniel Paul. “Monocular vision-aided inertial navigation for unmanned aerial vehicles.” 2015. Web. 17 Apr 2021.

Vancouver:

Magree DP. Monocular vision-aided inertial navigation for unmanned aerial vehicles. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/53892.

Council of Science Editors:

Magree DP. Monocular vision-aided inertial navigation for unmanned aerial vehicles. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53892

Georgia Tech

21. Agrawal, Gaurav. Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions.

Degree: PhD, Chemical and Biomolecular Engineering, 2014, Georgia Tech

URL: http://hdl.handle.net/1853/54028

► Simulated Moving Bed (SMB) chromatography is a separation process where the components are separated due to their varying affinity towards the stationary phase. Over the… (more)

▼ Simulated Moving Bed (SMB) chromatography is a separation process where the components are separated due to their varying affinity towards the stationary phase. Over the past decade, many modifications have been proposed in SMB chromatography in order to effectively separate a binary mixture. However, the separation of multi-component mixtures using SMB is still one of the major challenges. Although many different strategies have been proposed, previous studies have rarely performed comprehensive investigations for finding the best ternary separation strategy from various possible alternatives. Furthermore, the concept of combining reaction with SMB has been proposed in the past for driving the equilibrium limited reactions to completion by separating the products from the reaction zone. However, the design of such systems is still challenging due to the complex dynamics of simultaneous reaction and adsorption. The first objective of the study is to find the best ternary separation strategy among various alternatives design of SMB. The performance of several ternary SMB operating schemes, that are proposed in the literature, are compared in terms of the optimal productivity obtained and the amount of solvent consumed. A multi- objective optimization problem is formulated which maximizes the SMB productivity and purity of intermediate eluting component at the same time. Furthermore, the concept of optimizing a superstructure formulation is proposed, where numerous SMB operating schemes can be incorporated into a single formulation. This superstructure approach has a potential to find more advantageous operating scheme compared to existing operating schemes in the literature. The second objective of the study is to demonstrate the Generalized Full Cycle (GFC) operation experimentally for the first time, and compare its performance to the JO process. A Semba OctaveTM chromatography system is used as an experimental SMB unit to implement the optimal operating schemes. In addition, a simultaneous optimization and model correction (SOMC) scheme is used to resolve the model mismatch in a systematic way. We also show a systematic comparison of both JO and GFC operations by presenting a Pareto plot of the productivity achieved against the desired purity of the intermediate eluting component experimentally. The third objective of the study is to develop an simulated moving bed reactor (SMBR) process for an industrial-scale application, and demonstrate the potential of the ModiCon operation for improving the performance of the SMBR compared to the conventional operating strategy. A novel industrial application involving the esterification of acetic acid and 1-methoxy-2-propanol is considered to produce propylene glycol methyl ether (PMA) as the product. A multi-objective optimization study is presented to find the best reactive separation strategy for the production of the PMA product. We also present a Pareto plot that compares the ModiCon operation, which allows periodical change of the feed composition and the… Advisors/Committee Members: Kawajiri, Yoshiaki (advisor), Realff, Matthew J. (committee member), Grover, Martha (committee member), Nenes, Athanasios (committee member), Bommarius, Andreas S. (committee member), Tsiotras, Panagiotis (committee member).

Subjects/Keywords: Simulated moving bed chromatography; Reactive separation; Parameter estimation; Modeling and optimization; Ternary separation

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APA (6^th Edition):

Agrawal, G. (2014). Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/54028

Chicago Manual of Style (16^th Edition):

Agrawal, Gaurav. “Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions.” 2014. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/54028.

MLA Handbook (7^th Edition):

Agrawal, Gaurav. “Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions.” 2014. Web. 17 Apr 2021.

Vancouver:

Agrawal G. Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/54028.

Council of Science Editors:

Agrawal G. Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/54028

Georgia Tech

22. Cohen, Raphael P. Formal verification and validation of convex optimization algorithms for model predictive control.

Degree: PhD, Aerospace Engineering, 2018, Georgia Tech

URL: http://hdl.handle.net/1853/61186

► The efficiency of modern optimization methods, coupled with increasing computational resources, has led to the possibility of real-time optimization algorithms acting in safety critical roles.… (more)

Subjects/Keywords: Formal methods; Software verification; Frama-C; SMT solvers; Convex optimization; Ellipsoid method; Floating-points

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APA (6^th Edition):

Cohen, R. P. (2018). Formal verification and validation of convex optimization algorithms for model predictive control. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/61186

Chicago Manual of Style (16^th Edition):

Cohen, Raphael P. “Formal verification and validation of convex optimization algorithms for model predictive control.” 2018. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/61186.

MLA Handbook (7^th Edition):

Cohen, Raphael P. “Formal verification and validation of convex optimization algorithms for model predictive control.” 2018. Web. 17 Apr 2021.

Vancouver:

Cohen RP. Formal verification and validation of convex optimization algorithms for model predictive control. [Internet] [Doctoral dissertation]. Georgia Tech; 2018. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/61186.

Council of Science Editors:

Cohen RP. Formal verification and validation of convex optimization algorithms for model predictive control. [Doctoral Dissertation]. Georgia Tech; 2018. Available from: http://hdl.handle.net/1853/61186

23. McClain, Evan James. Metroplex identification, evaluation, and optimization.

Degree: PhD, Aerospace Engineering, 2013, Georgia Tech

URL: http://hdl.handle.net/1853/47692

► As airspace congestion becomes increasingly more common, one of the primary places airspace congestion is felt today, and will only continue to increase, is in… (more)

▼ As airspace congestion becomes increasingly more common, one of the primary places airspace congestion is felt today, and will only continue to increase, is in areas where more than one major airport interact. We will call these groups of interdependent airports a metroplex; a term originally coined to describe large metropolitan areas where more than one city of equal (or near equal) size or importance. These metroplex areas are of particular importance in understanding future capacity demands because many of these areas are currently experiencing problems with meeting the current demand, and demand is only projected to increase as air travel becomes more popular. Many of these capacity issues have been identified in the FAA's Future Airport Capacity Task (FACT). From the second FACT report, it is stated that "the FACT 1 analysis revealed that many of our hub airports and their associated metropolitan areas could be expected to experience capacity constraints (i.e. unacceptable levels of delay) by 2013 and 2020, even if the planned improvements envisioned at that time were completed." This analysis shows that the current methods of expanding airports will not scale with the growing demand. To address this growing demand, a three part solution is proposed. The first step is to properly identify the metroplex areas to be evaluated. While the FACT reports serve to identify areas where capacity growth does not meet demand, these areas are not grouped into metroplexes. To do this grouping, an interaction metric was developed based on airport distance and traffic volume. This interaction metric serves as a proxy for how the existence of a second airport impacts the operation of the first. This pairwise metric was then computed for all commercial airports in the US and were grouped into metroplexes using a clustering algorithm. The second obstacle was to develop a tool to evaluate each metroplex as new algorithms were tested. A discrete event based simulation was developed to model each link in the airspace structure for each aircraft that enters the TRACON. This program tracks the delay each aircraft is required to accumulate in holding patterns or traffic trombones. A third and final method discussed here was an optimization program that can be used to schedule aircraft that are entering the TRACON to perform small modifications in their speed while en route to reduce the overall delay (both en route and in the TRACON). While formal optimization methods for scheduling aircraft arrivals have been presented before, the computational complexity has greatly prevented such algorithms from being used to schedule many aircraft in a dense schedule. This is because mixed integer programming (MIP) is a NP-hard problem. Practically, this means that the solution time can grow exponentially as the problem size (number of aircraft) increases. To address this issue, a Benders' decomposition scheme was introduced that allows solutions to be computed in near real-time on commodity hardware. These solutions can be… Advisors/Committee Members: Clarke, John-Paul (Committee Chair), Feron, Eric (Committee Member), Johnson, Ellis (Committee Member), Tsiotras, Panagiotis (Committee Member), Volovoi, Vitali (Committee Member).

Subjects/Keywords: Scheduling; Metroplex; Clustering; Simulation; Airport capacity; Air traffic capacity

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APA (6^th Edition):

McClain, E. J. (2013). Metroplex identification, evaluation, and optimization. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/47692

Chicago Manual of Style (16^th Edition):

McClain, Evan James. “Metroplex identification, evaluation, and optimization.” 2013. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/47692.

MLA Handbook (7^th Edition):

McClain, Evan James. “Metroplex identification, evaluation, and optimization.” 2013. Web. 17 Apr 2021.

Vancouver:

McClain EJ. Metroplex identification, evaluation, and optimization. [Internet] [Doctoral dissertation]. Georgia Tech; 2013. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/47692.

Council of Science Editors:

McClain EJ. Metroplex identification, evaluation, and optimization. [Doctoral Dissertation]. Georgia Tech; 2013. Available from: http://hdl.handle.net/1853/47692

24. Kingston, Peter. Multi-agent coordination: fluid-inspired and optimal control approaches.

Degree: PhD, Electrical and Computer Engineering, 2012, Georgia Tech

URL: http://hdl.handle.net/1853/43714

► Multiagent coordination problems arise in a variety of applications, from satellite constellations and formation flight, to air traffic control and unmanned vehicle teams. We investigate… (more)

Subjects/Keywords: Multiagent coordination; Formation control; Networked control; Optimal control; Preference learning; Time warping; Output warping; Space warping; Machine learning; Multiagent systems; Automatic control

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APA (6^th Edition):

Kingston, P. (2012). Multi-agent coordination: fluid-inspired and optimal control approaches. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/43714

Chicago Manual of Style (16^th Edition):

Kingston, Peter. “Multi-agent coordination: fluid-inspired and optimal control approaches.” 2012. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/43714.

MLA Handbook (7^th Edition):

Kingston, Peter. “Multi-agent coordination: fluid-inspired and optimal control approaches.” 2012. Web. 17 Apr 2021.

Vancouver:

Kingston P. Multi-agent coordination: fluid-inspired and optimal control approaches. [Internet] [Doctoral dissertation]. Georgia Tech; 2012. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/43714.

Council of Science Editors:

Kingston P. Multi-agent coordination: fluid-inspired and optimal control approaches. [Doctoral Dissertation]. Georgia Tech; 2012. Available from: http://hdl.handle.net/1853/43714

25. Roberts, Richard Joseph William. Optical flow templates for mobile robot environment understanding.

Degree: PhD, Interactive Computing, 2014, Georgia Tech

URL: http://hdl.handle.net/1853/53473

► In this work we develop optical flow templates. In doing so, we introduce a practical tool for inferring robot egomotion and semantic superpixel labeling using… (more)

▼ In this work we develop optical flow templates. In doing so, we introduce a practical tool for inferring robot egomotion and semantic superpixel labeling using optical flow in imaging systems with arbitrary optics. In order to do this we develop valuable understanding of geometric relationships and mathematical methods that are useful in interpreting optical flow to the robotics and computer vision communities. This work is motivated by what we perceive as directions for advancing the current state of the art in obstacle detection and scene understanding for mobile robots. Specifically, many existing methods build 3D point clouds, which are not directly useful for autonomous navigation and require further processing. Both the step of building the point clouds and the later processing steps are challenging and computationally intensive. Additionally, many current methods require a calibrated camera, which introduces calibration challenges and places limitations on the types of camera optics that may be used. Wide-angle lenses, systems with mirrors, and multiple cameras all require different calibration models and can be difficult or impossible to calibrate at all. Finally, current pixel and superpixel obstacle labeling algorithms typically rely on image appearance. While image appearance is informative, image motion is a direct effect of the scene structure that determines whether a region of the environment is an obstacle. The egomotion estimation and obstacle labeling methods we develop here based on optical flow templates require very little computation per frame and do not require building point clouds. Additionally, they do not require any specific type of camera optics, nor a calibrated camera. Finally, they label obstacles using optical flow alone without image appearance. In this thesis we start with optical flow subspaces for egomotion estimation and detection of “motion anomalies”. We then extend this to multiple subspaces and develop mathematical reasoning to select between them, comprising optical flow templates. Using these we classify environment shapes and label superpixels. Finally, we show how performing all learning and inference directly from image spatio-temporal gradients greatly improves computation time and accuracy. Advisors/Committee Members: Dellaert, Frank (advisor), Essa, Irfan (committee member), Tsiotras, Panagiotis (committee member), De la Torre, Fernando (committee member), Rehg, James M. (committee member).

Subjects/Keywords: Mobile robots; Optical flow; Obstacle detection; Generalized imaging systems

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APA (6^th Edition):

Roberts, R. J. W. (2014). Optical flow templates for mobile robot environment understanding. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53473

Chicago Manual of Style (16^th Edition):

Roberts, Richard Joseph William. “Optical flow templates for mobile robot environment understanding.” 2014. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/53473.

MLA Handbook (7^th Edition):

Roberts, Richard Joseph William. “Optical flow templates for mobile robot environment understanding.” 2014. Web. 17 Apr 2021.

Vancouver:

Roberts RJW. Optical flow templates for mobile robot environment understanding. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/53473.

Council of Science Editors:

Roberts RJW. Optical flow templates for mobile robot environment understanding. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/53473

26. Salgueiro Filipe, Nuno Ricardo. Nonlinear pose control and estimation for space proximity operations: an approach based on dual quaternions.

Degree: PhD, Aerospace Engineering, 2014, Georgia Tech

URL: http://hdl.handle.net/1853/53055

► The term proximity operations has been widely used in recent years to describe a wide range of space missions that require a spacecraft to remain… (more)

▼ The term proximity operations has been widely used in recent years to describe a wide range of space missions that require a spacecraft to remain close to another space object. Such missions include, for example, the inspection, health monitoring, surveillance, servicing, and refueling of a space asset by another spacecraft. One of the biggest challenges in autonomous space proximity operations, either cooperative or uncooperative, is the need to autonomously and accurately track time-varying relative position and attitude references, i.e., pose references, with respect to a moving target, in order to avoid on-orbit collisions and achieve the overall mission goals. In addition, if the target spacecraft is uncooperative, the Guidance, Navigation, and Control (GNC) system of the chaser spacecraft must not rely on any help from the target spacecraft. In this case, vision-based sensors, such as cameras, are typically used to measure the relative pose between the spacecraft. Although vision-based sensors have several attractive properties, they introduce new challenges, such as no direct linear and angular velocity measurements, slow update rates, and high measurement noise. This dissertation investigates the problem of autonomously controlling and estimating the pose of a chaser spacecraft with respect to a moving target spacecraft, possibly uncooperative. Since this problem is inherently hard, the standard approach in the literature is to split the attitude-tracking problem from the position-tracking problem. Whereas the attitude-tracking problem is relatively simple, since the rotational motion is independent from the translational motion, the position-tracking problem is more complicated, as the translational motion depends on the rotational motion. Hence, whereas strong theoretical results exist for the attitude problem, the position problem typically requires additional assumptions. An alternative, more general approach to the pose control and estimation problems is to consider the fully coupled 6-DOF motion. However, fewer results exist that directly address this higher dimensional problem. The main contribution of this dissertation is to show that dual quaternions can be used to extend the theoretical results that exist for the attitude motion into analogous results for the combined position and attitude motion. Moreover, this dissertation shows that this can be accomplished by (almost) just replacing quaternions by dual quaternions in the original derivations. This is because dual quaternions are built on and are an extension of classical quaternions. Dual quaternions provide a compact representation of the pose of a frame with respect to another frame. Using this approach, three new results are presented in this dissertation. First, a pose-tracking controller that does not require relative linear and angular velocity measurements is derived with vision-based sensors in mind. Compared to existing literature, the proposed velocity-free pose-tracking controller guarantees that the pose of the chaser spacecraft… Advisors/Committee Members: Tsiotras, Panagiotis (advisor), Braun, Robert D. (committee member), Holzinger, Marcus (committee member), Russell, Ryan P. (committee member), Baldwin, Morgan (committee member).

Subjects/Keywords: Space proximity operations; Dual quaternions; Nonlinear control; Nonlinear estimation; Adaptive control; EKF; ASTROS facility

…ASTROS) facility at the School of Aerospace Engineering at Georgia Tech. xxvi Finally…

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APA (6^th Edition):

Salgueiro Filipe, N. R. (2014). Nonlinear pose control and estimation for space proximity operations: an approach based on dual quaternions. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53055

Chicago Manual of Style (16^th Edition):

Salgueiro Filipe, Nuno Ricardo. “Nonlinear pose control and estimation for space proximity operations: an approach based on dual quaternions.” 2014. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/53055.

MLA Handbook (7^th Edition):

Salgueiro Filipe, Nuno Ricardo. “Nonlinear pose control and estimation for space proximity operations: an approach based on dual quaternions.” 2014. Web. 17 Apr 2021.

Vancouver:

Salgueiro Filipe NR. Nonlinear pose control and estimation for space proximity operations: an approach based on dual quaternions. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/53055.

Council of Science Editors:

Salgueiro Filipe NR. Nonlinear pose control and estimation for space proximity operations: an approach based on dual quaternions. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/53055

27. Arslan, Oktay. Machine learning and dynamic programming algorithms for motion planning and control.

Degree: PhD, Aerospace Engineering, 2015, Georgia Tech

URL: http://hdl.handle.net/1853/54317

► Robot motion planning is one of the central problems in robotics, and has received considerable amount of attention not only from roboticists but also from… (more)

▼ Robot motion planning is one of the central problems in robotics, and has received considerable amount of attention not only from roboticists but also from the control and artificial intelligence (AI) communities. Despite the different types of applications and physical properties of robotic systems, many high-level tasks of autonomous systems can be decomposed into subtasks which require point-to-point navigation while avoiding infeasible regions due to the obstacles in the workspace. This dissertation aims at developing a new class of sampling-based motion planning algorithms that are fast, efficient and asymptotically optimal by employing ideas from Machine Learning (ML) and Dynamic Programming (DP). First, we interpret the robot motion planning problem as a form of a machine learning problem since the underlying search space is not known a priori, and utilize random geometric graphs to compute consistent discretizations of the underlying continuous search space. Then, we integrate existing DP algorithms and ML algorithms to the framework of sampling-based algorithms for better exploitation and exploration, respectively. We introduce a novel sampling-based algorithm, called RRT#, that improves upon the well-known RRT* algorithm by leveraging value and policy iteration methods as new information is collected. The proposed algorithms yield provable guarantees on correctness, completeness and asymptotic optimality. We also develop an adaptive sampling strategy by considering exploration as a classification (or regression) problem, and use online machine learning algorithms to learn the relevant region of a query, i.e., the region that contains the optimal solution, without significant computational overhead. We then extend the application of sampling-based algorithms to a class of stochastic optimal control problems and problems with differential constraints. Specifically, we introduce the Path Integral - RRT algorithm, for solving optimal control of stochastic systems and the CL-RRT# algorithm that uses closed-loop prediction for trajectory generation for differential systems. One of the key benefits of CL-RRT# is that for many systems, given a low-level tracking controller, it is easier to handle differential constraints, so complex steering procedures are not needed, unlike most existing kinodynamic sampling-based algorithms. Implementation results of sampling-based planners for route planning of a full-scale autonomous helicopter under the Autonomous Aerial Cargo/Utility System Program (AACUS) program are provided. Advisors/Committee Members: Tsiotras, Panagiotis (advisor), Feron, Eric (committee member), Theodorou, Evangelos (committee member), Dellaert, Frank (committee member), Song, Le (committee member), Karaman, Sertac (committee member).

Subjects/Keywords: Robotic motion planning; Sampling-based algorithms; Rapidly-exploring random trees; Dynamic programming; Machine learning; Closed-loop prediction; High-level route planning

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APA (6^th Edition):

Arslan, O. (2015). Machine learning and dynamic programming algorithms for motion planning and control. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/54317

Chicago Manual of Style (16^th Edition):

Arslan, Oktay. “Machine learning and dynamic programming algorithms for motion planning and control.” 2015. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/54317.

MLA Handbook (7^th Edition):

Arslan, Oktay. “Machine learning and dynamic programming algorithms for motion planning and control.” 2015. Web. 17 Apr 2021.

Vancouver:

Arslan O. Machine learning and dynamic programming algorithms for motion planning and control. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/54317.

Council of Science Editors:

Arslan O. Machine learning and dynamic programming algorithms for motion planning and control. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/54317

28. Wang, Timothy. Credible autocoding of control software.

Degree: PhD, Aerospace Engineering, 2015, Georgia Tech

URL: http://hdl.handle.net/1853/53954

► Formal methods is a discipline of using a collection of mathematical techniques and formalisms to model and analyze software systems. Motivated by the new formal… (more)

Subjects/Keywords: Formal methods; Control; Lyapunov; Safety-critical software; Model-based development; Verification & validation

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APA (6^th Edition):

Wang, T. (2015). Credible autocoding of control software. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53954

Chicago Manual of Style (16^th Edition):

Wang, Timothy. “Credible autocoding of control software.” 2015. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/53954.

MLA Handbook (7^th Edition):

Wang, Timothy. “Credible autocoding of control software.” 2015. Web. 17 Apr 2021.

Vancouver:

Wang T. Credible autocoding of control software. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/53954.

Council of Science Editors:

Wang T. Credible autocoding of control software. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53954

29. Spencer, David Allen. Automated trajectory control for proximity operations using relative orbital elements.

Degree: PhD, Aerospace Engineering, 2015, Georgia Tech

URL: http://hdl.handle.net/1853/53549

► This dissertation develops a methodology for automated trajectory control of a spacecraft about a non-maneuvering target. The methodology utilizes relative orbital elements (ROEs), combined with… (more)

▼ This dissertation develops a methodology for automated trajectory control of a spacecraft about a non-maneuvering target. The methodology utilizes relative orbital elements (ROEs), combined with guidance laws based upon artificial potential functions (APFs), to perform automated trajectory planning and maneuver design. The investigation provides a definitive reference on the definition and use of ROEs for relative proximity operations. The detailed derivation of ROEs is provided, along with transformations between ROEs and relative Cartesian state elements, characteristics of unforced motion in terms of ROEs, and the effect of impulsive maneuvers on ROEs. Operationally-useful guidance algorithms utilizing ROEs are developed and demonstrated. These ROE-based algorithms for rendezvous, circumnavigation and station-keeping provide a toolkit for relative proximity operations mission planning. A new approach for APF formulation using ROEs as the target variables is developed. While previous approaches allowed targeting of a specified relative position, the present approach allows the targeting of relative orbit geometries. The approach capitalizes upon the orbital dynamics represented through the ROEs, and retains the computational simplicity offered by the APFs. Formulations for the APF targeting of individual ROEs, as well as simultaneous targeting of a set of ROEs, are established. An approach for combining ROE targeting using APFs with obstacle avoidance is presented. The trajectory guidance algorithm performance is evaluated using a flight-like guidance, navigation and control simulation environment, including orbital perturbations. Algorithm performance is established through a set of operationally relevant scenarios. The guidance algorithms are shown to be capable of correcting for environmental disturbances, while meeting the targeted relative orbits in an automated fashion. Advisors/Committee Members: Braun, Robert D. (advisor), Costello, Mark (committee member), Tsiotras, Panagiotis (committee member), Erwin, Scott (committee member), Lovell, Thomas A. (committee member).

Subjects/Keywords: Orbital; Proximity operations; Automation

…fabricated and tested by a team of Georgia Tech undergraduate and graduate students who will also… …NASA USSR NASA NASA NASA NASDA AFRL AFRL NASA DARPA MIT ESA ESA Tyvak Georgia Tech Visible…

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APA (6^th Edition):

Spencer, D. A. (2015). Automated trajectory control for proximity operations using relative orbital elements. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53549

Chicago Manual of Style (16^th Edition):

Spencer, David Allen. “Automated trajectory control for proximity operations using relative orbital elements.” 2015. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/53549.

MLA Handbook (7^th Edition):

Spencer, David Allen. “Automated trajectory control for proximity operations using relative orbital elements.” 2015. Web. 17 Apr 2021.

Vancouver:

Spencer DA. Automated trajectory control for proximity operations using relative orbital elements. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/53549.

Council of Science Editors:

Spencer DA. Automated trajectory control for proximity operations using relative orbital elements. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53549

30. Alemany, Kristina. Design space pruning heuristics and global optimization method for conceptual design of low-thrust asteroid tour missions.

Degree: PhD, Aerospace Engineering, 2009, Georgia Tech

URL: http://hdl.handle.net/1853/31821

► Electric propulsion has recently become a viable technology for spacecraft, enabling shorter flight times, fewer required planetary gravity assists, larger payloads, and/or smaller launch vehicles.… (more)

▼ Electric propulsion has recently become a viable technology for spacecraft, enabling shorter flight times, fewer required planetary gravity assists, larger payloads, and/or smaller launch vehicles. With the maturation of this technology, however, comes a new set of challenges in the area of trajectory design. Because low-thrust trajectory optimization has historically required long run-times and significant user-manipulation, mission design has relied on expert-based knowledge for selecting departure and arrival dates, times of flight, and/or target bodies and gravitational swing-bys. These choices are generally based on known configurations that have worked well in previous analyses or simply on trial and error. At the conceptual design level, however, the ability to explore the full extent of the design space is imperative to locating the best solutions in terms of mass and/or flight times. Beginning in 2005, the Global Trajectory Optimization Competition posed a series of difficult mission design problems, all requiring low-thrust propulsion and visiting one or more asteroids. These problems all had large ranges on the continuous variables - launch date, time of flight, and asteroid stay times (when applicable) - as well as being characterized by millions or even billions of possible asteroid sequences. Even with recent advances in low-thrust trajectory optimization, full enumeration of these problems was not possible within the stringent time limits of the competition. This investigation develops a systematic methodology for determining a broad suite of good solutions to the combinatorial, low-thrust, asteroid tour problem. The target application is for conceptual design, where broad exploration of the design space is critical, with the goal being to rapidly identify a reasonable number of promising solutions for future analysis. The proposed methodology has two steps. The first step applies a three-level heuristic sequence developed from the physics of the problem, which allows for efficient pruning of the design space. The second phase applies a global optimization scheme to locate a broad suite of good solutions to the reduced problem. The global optimization scheme developed combines a novel branch-and-bound algorithm with a genetic algorithm and an industry-standard low-thrust trajectory optimization program to solve for the following design variables: asteroid sequence, launch date, times of flight, and asteroid stay times. The methodology is developed based on a small sample problem, which is enumerated and solved so that all possible discretized solutions are known. The methodology is then validated by applying it to a larger intermediate sample problem, which also has a known solution. Next, the methodology is applied to several larger combinatorial asteroid rendezvous problems, using previously identified good solutions as validation benchmarks. These problems include the 2nd and 3rd Global Trajectory Optimization Competition problems. The methodology is shown to be capable of achieving a… Advisors/Committee Members: Braun, Robert (Committee Chair), Clarke, John-Paul (Committee Member), Russell, Ryan (Committee Member), Sims, Jon (Committee Member), Tsiotras, Panagiotis (Committee Member).

Subjects/Keywords: Distributed computing; Lambert; MALTO; Combinatorial optimization; Heuristic algorithms; Combinatorial analysis; Electronic data processing Distributed processing

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APA (6^th Edition):

Alemany, K. (2009). Design space pruning heuristics and global optimization method for conceptual design of low-thrust asteroid tour missions. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/31821

Chicago Manual of Style (16^th Edition):

Alemany, Kristina. “Design space pruning heuristics and global optimization method for conceptual design of low-thrust asteroid tour missions.” 2009. Doctoral Dissertation, Georgia Tech. Accessed April 17, 2021. http://hdl.handle.net/1853/31821.

MLA Handbook (7^th Edition):

Alemany, Kristina. “Design space pruning heuristics and global optimization method for conceptual design of low-thrust asteroid tour missions.” 2009. Web. 17 Apr 2021.

Vancouver:

Alemany K. Design space pruning heuristics and global optimization method for conceptual design of low-thrust asteroid tour missions. [Internet] [Doctoral dissertation]. Georgia Tech; 2009. [cited 2021 Apr 17]. Available from: http://hdl.handle.net/1853/31821.

Council of Science Editors:

Alemany K. Design space pruning heuristics and global optimization method for conceptual design of low-thrust asteroid tour missions. [Doctoral Dissertation]. Georgia Tech; 2009. Available from: http://hdl.handle.net/1853/31821

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