Aerospace Engineering Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2737
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Item MECHANICAL DESIGN OF DEXTEROUS MANIPULATOR LINKS(2018) Carlsen, Christopher James; Akin, David L; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This paper explores the challenges of dense structure-electronics packaging, specifically for a structural and electronics upgrade to the Ranger Tele-robotic Shuttle Experiment (RTSX) manipulators at the University of Maryland (UMD). Long serial-link manipulators are popular in the space industry, where the need for a long reach and high manipulability outweighs the need for high tip stiffness. For larger systems with co-located electronics, such as those used to berth vehicles on orbit, electronics packaging is not inhibited by the diameter of the link body. As link diameter decreases, co-locating electronics in the manipulator becomes diffcult without adding external extensions to house them. In such densely packed bodies, the control electronics are so integrated with structure that electronics maintenance requires disassembly of primary structure.Item HUMAN FACTORS EVALUATION OF OPERATOR INTERFACES FOR TELEOPERATION OF A DEXTEROUS MANIPULATOR(2014) Davis, Kevin Patrick; Akin, David L; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Ground teleoperation of a satellite servicing spacecraft is a challenging task for a human operator, especially when there is significant communications delay between the control station and spacecraft. On-orbit operations are further complicated by a communications time delay between the ground and spacecraft. Operator performance can be improved with the use of a graphical simulation of the robot. By displaying the robot's commanded position, graphical simulation can also mitigate some effects of time delay. This work implemented a visualization tool and commanded display to assist operation of a remote dexterous manipulator. A Fitts' Law experiment was designed to determine the effectiveness of the commanded display in reducing the impact of time delay. The experiment was conducted with a six degree of freedom manipulator over a range of time delays, from 0.0 to 6.0 seconds. The experimental results were analyzed to assess the reduction of task completion time and operator workload.Item Kinematic Determination of an Unmodeled Serial Manipulator by Means of an IMU(2013) Ciarleglio, Constance; Akin, David L; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Kinematic determination for an unmodeled manipulator is usually done through a-priori knowledge of the manipulator physical characteristics or external sensor information. The mathematics of the kinematic estimation, often based on Denavit- Hartenberg convention, are complex and have high computation requirements, in addition to being unique to the manipulator for which the method is developed. Analytical methods that can compute kinematics on-the fly have the potential to be highly beneficial in dynamic environments where different configurations and variable manipulator types are often required. This thesis derives a new screw theory based method of kinematic determination, using a single inertial measurement unit (IMU), for use with any serial, revolute manipulator. The method allows the expansion of reconfigurable manipulator design and simplifies the kinematic process for existing manipulators. A simulation is presented where the theory of the method is verified and characterized with error. The method is then implemented on an existing manipulator as a verification of functionality.Item Design and Evaluation of End-Effectors for Autonomous Sampling(2008-09-16) Lewandowski, Craig Michael; Akin, David; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Autonomous underwater vehicles are becoming increasingly prevalent, and their emergence will allow for the execution of previously unfeasible underwater missions. These missions include seeking naval mines, navigation and mapping of ocean features, and sampling on the ocean floor at extreme depths. One method to achieve this latter objective involves the attachment of a robotic manipulator to an underwater vehicle and use of the manipulator to collect specimens and deposit them in containers. This thesis focuses on the design and testing of an end-effector to be used on such a manipulator. End-effectors previously utilized in underwater robotics were evaluated during the conceptualization of the selected tool design. These evaluations in conjunction with manipulator interface requirements were used to produce the end-effector design that was constructed and subsequently tested. In addition, sample containers were designed and fabricated, and kinematics software used to determine sample container position, orientation, and quantity was developed.