Aerospace Engineering

Permanent URI for this communityhttp://hdl.handle.net/1903/2206

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Subject: search.filters.subject.Engineering, Robotics

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Now showing 1 - 5 of 5
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    OPTIC FLOW BASED STATION-KEEPING AND WIND REJECTION FOR SMALL FLYING VEHICLES
    (2010) Patrick, Bryan; Humbert, James S.; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Optic flow and Wide Field Integration (WFI) have shown potential for application to autonomous navigation of Unmanned Air Vehicles (UAVs). In this study the application of these same methods to other tasks, namely station-keeping and wind rejection, is examined. Theory surrounding optic flow, WFI and wind gust modeling is examined to provide a theoretical background. A controller based on a H∞ bounded formulation of the well known Linear Quadratic Regulator in designed to both mitigate wind disturbances and station-keep. The performance of this controller is assessed via simulation to determine both performance and trade-offs in implementation such as the method for optic flow calculation. Furthermore, flight tests are performed to examine the real world effectiveness of the controller. Finally, conclusions about potential improvement to implementation are drawn.
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    Development of a reusable top-level control architecture for a robotic manipulator
    (2010) D'Amore, Nicholas; Akin, David; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The capabilities of a robotic system are strongly constrained by the capabilities of its control software. The development of this software represents a substantial fraction of the development effort of the overall system, due in part to the difficulty of reusing software written for previous robotic applications. A reusable software control architecture therefore has enormous potential to expedite the development and reduce the cost of this development process. This thesis presents a component-based reusable architecture for the top-level control of a robotic manipulator, developed within the Open Robot Control Software (Orocos) framework. This framework enables the development of software components that are applicable to a variety of robotic manipulators. The software is implemented on an existing manipulator platform as a demonstration of basic functionality. Simulations are conducted to verify adaptability to other kinematic arrangements.
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    Bio-Inspired Information Extraction In 3-D Environments Using Wide-Field Integration Of Optic Flow
    (2010) Hyslop, Andrew Maxwell; Humbert, James S; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    A control theoretic framework is introduced to analyze an information extraction approach from patterns of optic flow based on analogues to wide-field motion-sensitive interneurons in the insect visuomotor system. An algebraic model of optic flow is developed, based on a parameterization of simple 3-D environments. It is shown that estimates of proximity and speed, relative to these environments, can be extracted using weighted summations of the instantaneous patterns of optic flow. Small perturbation techniques are utilized to link weighting patterns to outputs, which are applied as feedback to facilitate stability augmentation and perform local obstacle avoidance and terrain following. Weighting patterns that provide direct linear mappings between the sensor array and actuator commands can be derived by casting the problem as a combined static state estimation and linear feedback control problem. Additive noise and environment uncertainties are incorporated into an offline procedure for determination of optimal weighting patterns. Several applications of the method are provided, with differing spatial measurement domains. Non-linear stability analysis and experimental demonstration is presented for a wheeled robot measuring optic flow in a planar ring. Local stability analysis and simulation is used to show robustness over a range of urban-like environments for a fixed-wing UAV measuring in orthogonal rings and a micro helicopter measuring over the full spherical viewing arena. Finally, the framework is used to analyze insect tangential cells with respect to the information they encode and to demonstrate how cell outputs can be appropriately amplified and combined to generate motor commands to achieve reflexive navigation behavior.
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    A LINE-BASED OBSTACLE AVOIDANCE TECHNIQUE FOR DEXTEROUS MANIPULATOR OPERATIONS
    (2007-08-06) Scott, Nicholas; Carignan, Craig; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Both autonomous and teleoperated tasks with a dexterous manipulator often use cameras for external sensing. For teleoperated tasks, an array of cameras is typically used to provide the operator with multiple two-dimensional views of the manipulator workspace. For autonomous operations, cameras are used for visual servoing or to produce a map of the environment in the manipulator workspace. Nominal operations will likely produce manipulator configurations that occlude the line of sight from the camera to a target of interest. One possible approach is to treat the camera line of sight as a virtual obstacle to prevent camera occlusion. This approach is demonstrated on the Ranger dexterous manipulator for a variety of task configurations. Extension of this approach to non-redundant manipulators is also considered.
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    Hardware Design of a Wearable System for Gesture-Based Teleoperation of a Robotic Manipulator
    (2007-06-05) Buchholz, Brooke Teresa; Akin, David; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    To overcome some of the difficulties of robotic teleoperation using hand controllers, a new approach is necessary, namely gesture-based control. A review of sensors currently in use for human joint angle measurement is presented. Based on this review, a method was chosen that uses a variable-length fiber optic sensor. Several different types of optical fibers, along with a variety of test configurations, were initially evaluated, and the most promising of these were selected for further testing. This thesis describes these methods of evaluation and the final system design and testing of a wearable system for gesture-based control of a robotic manipulator, including a discussion of sensor placement to obtain improved results. The final system presented requires improvements and continued research to become usable for robotic control. However, the basic concept and design are shown to provide reliable information regarding relative human joint motion.