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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    Control and Stabilization of Soft Inverted Pendulum on a Cart
    (2023) Ajithkumar, Ananth; Chopra, Nikhil Dr.; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Underactuated systems are systems that cannot be controlled to track any arbitrary trajectories in their configuration space. In this work, we introduce a novel soft-robotic pendulum on a cart system. This is an underactuated soft-robotic system with two degrees of under-actuation. We model the system, derive the kinematics, and motivated by the control strategies for classical underactuated systems, we study the swing-up control and stabilization of this system around the vertical equilibrium point. The switching-based control law uses an energy-based control for swing-up and LQR for stabilization once the system is within the region of attraction of LQR. The simulation results depict the efficaciousness of the developed control scheme. Further, in this thesis, we discuss the viability and feasibility of feedback linearization, partially feedback-linearize the system, and analyze the zero dynamics of the system.
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    ROBUST CONTROL OF AN EVTOL THROUGH TRANSITION WITH A GAIN SCHEDULING LQR CONTROLLER
    (2020) Thompson, Derek; Xu, Huan; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The advancements in electric motor propulsion and battery technologies have made the implementation of electric power in aerial transportation increasingly feasible. As such, the interest and development of electric vertical takeoff and landing (eVTOL) aircraft has become a greater portion of the market. This increase drives a need for research into control of the eVTOLs to ensure safe flight through the transition from hover to forward flight. This paper proposes a control strategy using the transition dynamics in a gain scheduling LQR attitude controller to robustly control the vehicle at any point throughout transition. The proposed control strategy is tested through implementation in nonlinear 3DOF and 6DOF simulations. The robustness of the controller is tested through simulating transition and virtual mission profiles.
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    Design and Implementation of a Control System for a Quadrotor MAV
    (2012) Bawek, Dean; Chopra, Inderjit; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The quadrotor is a 200 g MAV with rapid-prototyped rotors that are driven by four brushless electric motors, capable of a collective thrust of around 400 g using an 11 V battery. The vehicle is compact with its largest dimension at 188 mm. Without any feedback control, the quadrotor is unstable. For flight stability, the vehicle incorporates a linear quadratic regulator to augment its dynamics for hover. The quadrotor's nonlinear dynamics are linearized about hover in order to be used in controller formulation. Feedback comes both directly from sensors and a Luenberger observer that computes the rotor velocities. A Simulink simulation uses hardware and software properties to serve as an environment for controller gain tuning prior to flight testing. The results from the simulation generate stabilizing control gains for the on-board attitude controller and for an off-board PC autopilot that uses the Vicon computer vision system for position feedback. Through the combined effort of the on-board and off-board controllers, the quadrotor successfully demonstrates stable hover in both nominal and disturbed conditions.