Design and Development of a High-Performance Quadrotor Control Architecture Based on Feedback Linearization

The purpose of this thesis is to outline the development of a high-performance quadrotor control system for an AscTec Hummingbird quadrotor using direct motor speed control within a Vicon motion capture system environment. A Ground Control Station (GCS) acts as a user interface for selecting flight patterns and displaying sensor values. An on-board Intel Edison embedded Linux computer acts as the quadrotor\u27s controller. The Vicon system measures the quadrotor\u27s position and orientation, while the Hummingbird\u27s stock AscTec Autopilot board provides inertial measurements and receives motor speed commands. Based on the flight pattern set by the GCS, smooth and di erentiable trajectories are generated. A control program was written for the Edison to obtain measurements, receive flight pattern commands, perform state estimation, calculate control laws, send motor speed commands to the Autopilot board, and log values. The program was written as a multithreaded C++ program for increased performance. A feedback linearization of the quadrotor\u27s dynamics was performed to account for its nonlinearities. A controller structure designed to ensure exponential Lyapunov stability was applied to the input-output linearized dynamics. The simplex method was used to aid the controller in pushing the Hummingbird\u27s actuators for aggressive maneuvers within set input limitations. The Edison\u27s Wi-Fi capabilities enable it to contact the Vicon server directly for position and orientation measurements. Accelerations and angular velocities are measured by the Autopilot\u27s inertial measurement unit (IMU). A quick state estimation process was implemented to filter the measured states, and state prediction was used to compensate for latency in the system. A custom circuit board and communication framework was designed and assembled for interfacing the Edison with the Autopilot. The custom communication framework allowed for a 16 times speed improvement over the default settings while bypassing the stock wireless communication\u27s inherently unreliable timing. The Hummingbird\u27s physical properties, such as propeller performance and rotational inertias, were characterized via static and step response experiments. The control system\u27s flight performance was evaluated through simulation and experimental tests

Trends in Public Opinion, 1989-1996

In this chapter, we examine the party identifications and ideological orientations of Tennesseans from 1989 through 1996, as revealed through survey research. We also look at Tennesseans\u27 positions on several issues of public policy that have been salient in state politics during this period. Our intent is to isolate any trends in the partisan and ideological character of the state while examining citizens\u27 positions on key issues

A spheroid toxicity assay using magnetic 3D bioprinting and real-time mobile device-based imaging

An ongoing challenge in biomedical research is the search for simple, yet robust assays using 3D cell cultures for toxicity screening. This study addresses that challenge with a novel spheroid assay, wherein spheroids, formed by magnetic 3D bioprinting, contract immediately as cells rearrange and compact the spheroid in relation to viability and cytoskeletal organization. Thus, spheroid size can be used as a simple metric for toxicity. The goal of this study was to validate spheroid contraction as a cytotoxic endpoint using 3T3 fibroblasts in response to 5 toxic compounds (all-trans retinoic acid, dexamethasone, doxorubicin, 5′-fluorouracil, forskolin), sodium dodecyl sulfate (+control), and penicillin-G (−control). Real-time imaging was performed with a mobile device to increase throughput and efficiency. All compounds but penicillin-G significantly slowed contraction in a dose-dependent manner (Z’ = 0.88). Cells in 3D were more resistant to toxicity than cells in 2D, whose toxicity was measured by the MTT assay. Fluorescent staining and gene expression profiling of spheroids confirmed these findings. The results of this study validate spheroid contraction within this assay as an easy, biologically relevant endpoint for high-throughput compound screening in representative 3D environments

Variations in IC50 Values with Purity of Mushroom Tyrosinase

The effects of various inhibitors on crude, commercial and partially purified commercial mushroom tyrosinase were examined by comparing IC50 values. Kojic acid, salicylhydroxamic acid, tropolone, methimazole, and ammonium tetrathiomolybdate had relatively similar IC50 values for the crude, commercial and partially purified enzyme. 4-Hexylresorcinol seemed to have a somewhat higher IC50 value using crude extracts, compared to commercial or purified tyrosinase. Some inhibitors (NaCl, esculetin, biphenol, phloridzin) showed variations in IC50 values between the enzyme samples. In contrast, hydroquinone, lysozyme, Zn2+, and anisaldehyde showed little or no inhibition in concentration ranges reported to be effective inhibitors. Organic solvents (DMSO and ethanol) had IC50 values that were similar for some of the tyrosinase samples. Depending of the source of tyrosinase and choice of inhibitor, variations in IC50 values were observed

Large-amplitude driving of a superconducting artificial atom: Interferometry, cooling, and amplitude spectroscopy

Superconducting persistent-current qubits are quantum-coherent artificial atoms with multiple, tunable energy levels. In the presence of large-amplitude harmonic excitation, the qubit state can be driven through one or more of the constituent energy-level avoided crossings. The resulting Landau-Zener-Stueckelberg (LZS) transitions mediate a rich array of quantum-coherent phenomena. We review here three experimental works based on LZS transitions: Mach-Zehnder-type interferometry between repeated LZS transitions, microwave-induced cooling, and amplitude spectroscopy. These experiments exhibit a remarkable agreement with theory, and are extensible to other solid-state and atomic qubit modalities. We anticipate they will find application to qubit state-preparation and control methods for quantum information science and technology.Comment: 13 pages, 5 figure

Empirical Evidence for Son-Killing X Chromosomes and the Operation of SA-Zygotic Drive

Diploid organisms have two copies of all genes, but only one is carried by each haploid gamete and diploid offspring. This causes a fundamental genetic conflict over transmission rate between alternative alleles. Single genes, or gene clusters, only rarely code for the complex phenotypes needed to give them a transmission advantage (drive phenotype). However, all genes on a male's X and Y chromosomes co-segregate, allowing different sex-linked genes to code for different parts of the drive phenotype. Correspondingly, the well-characterized phenomenon of male gametic drive, occurring during haploid gametogenesis, is especially common on sex chromosomes. The new theory of sexually antagonistic zygotic drive of the sex chromosomes (SA-zygotic drive) extends the logic of gametic drive into the diploid phase of the lifecycle, whenever there is competition among siblings or harmful sib-sib mating. The X and Y are predicted to gain a transmission advantage by harming offspring of the sex that does not carry them.Here we analyzed a mutant X-chromosome in Drosophila simulans that produced an excess of daughters when transmitted from males. We developed a series of tests to differentiate between gametic and SA-zygotic drive, and provide multiple lines of evidence that SA-zygotic drive is responsible for the sex ratio bias. Driving sires produce about 50% more surviving daughters than sons.Sex-ratio distortion due to genetic conflict has evolved via gametic drive and maternally transmitted endosymbionts. Our data indicate that sex chromosomes can also drive by harming the non-carrier sex of offspring

Quantum bits with Josephson junctions

Already in the first edition of this book (Barone and Paterno, "Fundamentals and Physics and Applications of the Josephson Effect", Wiley 1982), a great number of interesting and important applications for Josephson junctions were discussed. In the decades that have passed since then, several new applications have emerged. This chapter treats one such new class of applications: quantum optics and quantum information processing (QIP) based on superconducting circuits with Josephson junctions. In this chapter, we aim to explain the basics of superconducting quantum circuits with Josephson junctions and demonstrate how these systems open up new prospects, both for QIP and for the study of quantum optics and atomic physics.Comment: 30 pages, 10 figures. Book chapter for a new edition of Barone and Paterno's "Fundamentals and Physics and Applications of the Josephson Effect". Final versio