Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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    Revolutionary Flight Vehicle Based on Leonardo da Vinci Aerial Screw: A Paradigm Shift in VTOL Technology
    (2022) Prete, Austin Christopher; Chopra, Inderjit; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Aerial screws are rotors that consist of continuous large solidity single surface blades, which are able to provide significant thrust and control authority at increased power consumption when compared to traditional rotor blades. By leveraging a unique bound tip vortex, also observed in delta-wings, aerial screws are able to attain figure of merit values nearing 0.7 or higher, comparable to a modern rotorcraft. To prove the function of aerial screws, physical models were fabricated and flight tested. The primary objective of this paper is to explore the performance of a 6-in (0.152 m) diameter aerial screw and compare its performance with a 6-in (0.152 m) diameter traditional rotor, to demonstrate its feasibility in a quadrotor configuration and to show its efficiency as determined in the student designs from the 2019-2020 VFS student design competition.
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    A Self-Sealing Suction Technology for Versatile Grasping
    (2018) Kessens, Chad; Desai, Jaydev P; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This thesis describes the design, development, and evaluation of a novel "self-sealing" suction technology for grasping. As humans desire robots capable of handling an increasingly diverse set of tasks, end effectors that are able to grasp the widest possible range of object shapes and sizes will be needed to achieve the desired versatility. Technologies enabling the exertion of local pulling contact forces (e.g. suction) can be extraordinarily useful toward this end by handling objects that do not have features smaller than the grasper, a challenge for traditional grippers. However, simple operation and cost effectiveness are also highly desirable. To achieve these goals, we have developed a self-sealing suction technology for grasping. A small valve inside each suction cup nominally seals the suction port to maintain a vacuum within the system. Through the reaction forces of object contact, a lever action passively lifts the valve to engage suction on the object. Any cups not contacting the object remain sealed. In this way, a system with a large number of cups may effectively operate using any subset of its cups, even just one, to grasp an object. All cups may be connected to a central vacuum source without the need for local sensors or powered actuators for operation, forming a simple, compact, cost effective system. This thesis begins with the detailed design and analysis of the self-sealing suction technology. An extensive evaluation of the technology's robustness and performance demonstrates its features and limits. This includes self-seal quality and leakage, object seal and reseal, cycle performance, and normal and shear force-displacement, among other characterizations. It then describes the development of several devices utilizing the technology. The potential impact of the technology is highlighted through applications of human-controlled, robotic, and aerial grasping and perching. Finally, mathematical tools are developed to analyze potential grasps developed using the technology.