Theses and Dissertations - Department of Computer Science

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Algorithms with applications in robotics
(University of Alabama Libraries, 2009) Munteanu, Bogdan; Borie, Richard B.; University of Alabama Tuscaloosa
Many real world applications which involve computational steps are closely tied to theoretical computer science. In order for these systems to be efficiently deployed and used, a thorough analysis is required in advance. This dissertation deals with several real world problems related to the field of Robotics, which can be mathematically modeled and analyzed. One of these problems is known as the pursuit evasion problem and involves the use of independent automated robots to capture a fugitive hiding in a building or a cave system. This is an extensively studied game theory and combinatorics problem which has multiple variations. It can be modeled as a graph and the goal is to minimize the cost of capturing the evader. We deal with two completely different variations of this problem: a vision based variant, in which the robots have limited vision and thus can react when the fugitive is in line of sight; and a no-vision variant, in which the robots do not have any knowledge about the fugitive. Another problem we deal with is the problem of neighbor discovery in wireless networks using directional antennas. This is another problem which received a growing interest in the last years. Our approach to solving this problem, as well as the model, is different from the other results that have been previously published in the literature. Besides modeling and formally analyzing these problems, our focus in this dissertation is to design efficient algorithms that solve them either completely or partially.
Cooperation paradigms for overcoming communication limitations in multirobot wide area coverage
(University of Alabama Libraries, 2011) Wellman, Briana Lowe; Anderson, Monica D.; University of Alabama Tuscaloosa
Multi-robot systems are an important research topic in wide area coverage applications such as hazardous waste clean-up, bomb detection, surveillance, and search and rescue missions. They can work in parallel and complete tasks faster than a single robot. Communications can support cooperation to speed up execution, reduce duplication, and prevent interference. Communication among team members is achieved explicitly or implicitly. In explicit communication, messages are intentionally transmitted and received from robot to robot. In implicit communication, robots observe the environment and other robot actions. Although many systems use explicit communications, in exploration of large, open areas (e.g. stadiums and parks), persistent intra-team digital communications is not guaranteed. Therefore, alternative approaches that do not rely upon message passing throughout exploration are needed. Novel contributions of overcoming communication limitations in wide area coverage include: (1) insight on how information shared between robots that are close has more influence on immediate action selection than information shared between robots that are farther apart. Spatial and temporal locality can be instrumental in determining relevance in subsequent action selection; (2) an approach in which observation leverages spatial and temporal locality to infer state rather than rely on digital messaging; and (3) an approach in which robots use spatial rendezvous to exchange information instead of continuously passing messages. Robots explore an environment in sectors, or designated areas, and periodically meet to communicate map information of what they explored. Simulations and physical experiments were conducted and results suggest both approaches can serve as alternatives to cooperation based on continuous point-to-point communications.
Facilitating operator interaction with quality of surveillance multi-robot systems
(University of Alabama Libraries, 2012) Dawson, Shameka; Anderson, Monica D.; University of Alabama Tuscaloosa
Robotic systems are becoming more practical in military applications. In fact, unmanned aerial vehicles (UAVs) are being used for surveillance and reconnaissance missions. Using UAVs for surveying a region of interest can increase situational awareness and decrease human casualty by allowing the operator to view the video feeds from the UAVs. However, current systems utilize complex one (or multiple) operator/one robot interfaces. In addition, human-in-the-loop models create issues because human operators tend to intervene more frequently if they do not trust the system or their expectations of the autonomy are not met. As a result, excessive or inept human intervention could negatively affect workload, situational awareness, and performance. This dissertation is aimed at allowing a single operator to efficiently manage multiple UAVs and interact effectively with higher levels of autonomy. By providing the operator with a mechanism to interact with the autonomy and aid in decision making, the operator becomes a part of the autonomous team. Contributions of this dissertation related to facilitating operator interaction with multi-robot surveillance systems include: (1) knowledge that trust is more than an understanding that the actions of an autonomous team are rational, but related to experiencing the actions' rationale; (2) a novel approach to teaming based on spatial and temporal environmental cues; and (3) the design and implementation of a testbed to measure the effect of the operator teaming with an autonomous system. Studies are used to evaluate the system and elucidate factors that affect operator trust. Results suggest that a human operator can team with multiple robots and effectively interact with higher levels of autonomy by experiencing the autonomous team's rationale using environmental cues. This approach using the spatial and temporal environmental cues was also found to promote trust, lower workload, and increase situational awareness while not degrading task performance.
Home area network security and accountability in the smart grid
(University of Alabama Libraries, 2015) McCary, Eric Anthony; Xiao, Yang; University of Alabama Tuscaloosa
The presented dissertation concentrates on the security landscape in smart grid and proposes works to create a more accountable environment in the smart grid home area network (HAN). The principal thought behind the research is security and accountability in the smart grid and the smart grid HAN. Creating a more accountable HAN environment is essential in addressing these matters. More specifically, accountability as it pertains to the HAN, can be described as an assurance that each device within the HAN is held responsible for its own behavior and that those behaviors which belong to it are all provable and non-repudiation is upheld at a more intricate level than current offerings provide. Therefore, the dissertation addresses accountability in the HAN by methods implementing fine grained observation and monitoring of the devices therein. The first work of the dissertation addresses security in the smart grid. Recent work in smart grid has failed to give detailed holistic accounts of techniques which exploit several issues and vulnerabilities within the infrastructure and software which makes up the smart grid. Therefore, a holistic view which covers malicious actions and their impact on the grid and its components is provided. Countermeasures for these exploits are also discussed. Next, we propose an accountable method which provides for grouping and inspection of the devices in the HAN in order to efficiently pinpoint malicious and malfunctioning devices therein. The experimental results show that the method is effective in its efficiency and scheme. Lastly, we develop a method which addresses accountability of devices in the HAN which use varying amounts of energy during its operational phases. Method analysis and simulation results show that the method is effective, and that the method maintains a false alarm and error rate that is acceptable based on today's standards without prolonged training times.
Measuring the effects of low assistive vs. moderately assistive environments on novice programmers
(University of Alabama Libraries, 2012) Dillon, Edward; Brown, Marcus E.; University of Alabama Tuscaloosa
Improving the novice's experience with programming has been an important research topic for some time. The high attrition rate of CS majors continues to be a problem. Incoming majors are being exposed to programming but many are driven away from the field. As a way to engage novices with programming, many CS departments have adopted visual environments. However, not all novices are taught to program using visual environments. Typically, students are introduced to programming through either a visual or command line environment at the beginning stages of a CS curriculum. The features in standard command line environments are not as assistive to programmers as visual environments. Novices must learn both language syntax and semantics while navigating the file system and compilation tools. On the other hand, visual environments with highly assistive features could constrict a novice to learn a fixed set of foundational programming skills that exclude exposure to syntax checking, compilation and file systems. Novices will eventually need to move to a less assistive environment to round out their skill set. The objective of this research was to determine if certain environments are more appropriate for teaching novices how to program, based on their respective levels of feature assistance. There are anecdotally based motivations for using either tools with low assistive features like command line environments (promotes acquisition of useful mental models) or tools with moderate to high assistive features like visual environments (engages novices while programming). Unfortunately, no systematic study exists that supports either supposition. This research was composed of three studies for evaluating environments with varying feature sets: a high school outreach, a CS1-Laboratory Study, and a CS1-Study. Engagement, comprehension, efficiency, and usability were used as measures to evaluate the environments during these studies. Overall, this research showed that a moderately assistive environment imposes a lower learning curve for novices, while a low assistive environment appears to broaden their understanding of programming.
RDIS: a domain model for generalizing the mappings between robotic software frameworks and robotic devices
(University of Alabama Libraries, 2012) Kilgo, Paul Michael; Anderson, Monica D.; University of Alabama Tuscaloosa
Researchers, hobbyists, and industrial professionals alike have moved toward a framework-based approach to robotics application development. This allows robotic applications to be written for the domain of the framework and benefits the application developer as it offers domain-specific abstractions and reusability of applications. However, a framework must still know how to translate its domain-specific concepts to the device-specific concepts. One can do this in a general-purpose programming language, but this strategy is not sustainable because drivers must be hand-crafted for each possible permutation of framework and device. Therefore, exploring the appropriate level of abstraction for device drivers is interesting and may enable a description of a robot for it to be used with any robotics framework. A domain model for defining these mappings has been developed. The domain model allows descriptions of robots to be reused between frameworks. The specific mechanism for this is to describe the domain model using a textual syntax and interpret the description at run-time. One may then define the transformation of framework domain concepts to concepts native to the domain model as an adapter. Thus, any appropriately enabled robotic framework and device can communicate with one another. As further evidence for the viability of the domain model, it was implemented formally using the model-driven tool \atommm. One may then design the model at a high-level directly in the terms introduced by the model without the mental load posed by the textual syntax. As well, the tool presents a preliminary approach for generating adapters for frameworks. Future directions for the domain model include kinematic state modeling. A literature review and a preliminary approach for this has also been prepared.
Thunder: a private cloud architecture designed for high usability
(University of Alabama Libraries, 2015) Loewen, Gabriel J.; Vrbsky, Susan V.; University of Alabama Tuscaloosa
Cloud computing is a technological strategy for saving time, money, and resources within an organization. Underfunded and understaffed organizations benefit the most from a cloud architecture because it can help to alleviate a cost burden allowing funds to be used more effectively. Therefore, we believe that non-profit organizations, such as schools, libraries, non-profit medical facilities, and others have the most to gain from cloud computing. Cloud computing has played a major role in shaping large for-profit businesses like Google, Amazon, and Microsoft. Research has suggested that cultural barriers make it difficult for professionals in non-profits to adopt cloud computing technology. One key challenge faced by organizations for which a cloud architecture would be beneficial is the deployment and management process. In order for private cloud computing to become a viable solution for struggling organizations, much work needs to be done to simplify and improve the deployment process. We describe a new cloud architecture called THUNDER, which is a recursive backronym meaning ``THUNDER Helps Underfunded Nonprofits Distribute Electronic Resources.'' THUNDER introduces strategies which are meant to help struggling organizations to decrease costs. Virtual machine load balancing attempts to distribute the load across multiple nodes in order to maximize potential performance of virtual machines. Virtual machine consolidation attempts to utilize as few computational resources as possible in order to maximize the potential cost savings of maintaining idle nodes. We present an evaluation of THUNDER using metrics designed to compare its ease of use with that of other architectures. We also present an empirical evaluation of THUNDER by which users deploy and use the architecture, and then participate in a survey. THUNDER utilizes a new load balancing algorithm, which we have called ``RAIN'', meaning ``Rating Assisted Instantiation Negotiation''. RAIN attempts to optimize virtual machine instance placement by choosing compute nodes that have the best potential based on real-time metrics aggregation and a rating algorithm. Results show that the THUNDER is preferable for inexperienced users when compared to that of OpenStack and Eucalyptus. Additionally, experimental results show that RAIN is more efficient at placing virtual machines than the more typical approach of round-robin.

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Browsing Theses and Dissertations - Department of Computer Science by Author "Anderson, Monica D."

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