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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

MODULAR AFFORDABLE GPS/INS (MAGI)

Singh, Mahendra, McNamee, Stuart, Khosrowabadi, Allen 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The GPS/INS equipment is used at the Air Force Flight Test Center (AFFTC) to collect time space position information (TSPI) during testing. The GPS-based test instrumentation is lagging behind available commercial technologies. Advancing technologies for test use requires investigation of affordable commercial equipment. To enable technology insertion for state of the art testing, there is a need for more robust, flexible, reliable, modular, affordable low cost TSPI systems capable of operating in all flight environments. Modular (plug-and-play) hardware and software, quick and easy to re-configure, are required for supporting various test platforms from fighter aircraft to cargo size aircraft. Flight testing dynamics are such that, GPS-only systems tend to lose data during critical maneuvers. To minimize this data loss, inertial measurement systems coupled with GPS sensors are used in most sophisticated range instrumentation packages. However, these packages have required fairly expensive inertial units, are usually very large and not very flexible in terms of quick and easy reconfiguration to meet the unique needs of AFFTC’s test customers. WADDAN SYSTEMS has begun to address this problem with a modular design concept, which incorporates their high-performance navigation quality inertial measurement unit, but with costs comparative to that of lower-end performance inertial units. This paper describes WADDAN’s concept and the components that make up MAGI; and addresses some of the preliminary testing and near-term proposed activities. In general, the system will provide GPS, inertial and discrete MIL-STD 1553, RS-232/422 and video data from the participant. The MAGI will be structured around the Compact personal computer interface (PCI) backplane bus with on-board recording and processing and will include real-time command and control through a UHF data link.
12

Study of high-harmonic gyro-devices in the THz range

Li, Xiang January 2016 (has links)
In the terahertz (THz) band, high-harmonic operations of gyro-devices are attractive for the great potential to reduce the required external magnetic field strength, which is proportional to the oscillation frequency but inversely proportional to the operational harmonics. This thesis focuses on the study of high-harmonic operation of the gyro-devices. Specifically, a high-harmonic large-orbit gyrotron (LOG) and the output system for a gyro-multiplier will be investigated. Firstly, the complex-cavity gyrotron, which is the foundation of the gyro-multiplier scheme, is studied by programming and computer simulation. The computer code and the complex-cavity operation are then verified by three-dimensional (3D) Particle-In-Cell (PIC) simulation. The code can be used as a preliminary design tool of the beam-wave interaction cavity for both the LOG and the gyro-multiplier. Secondly, a high-harmonic LOG operating with the TEm,1,1 modes (m=4-9) has been designed and investigated. It is shown that by proper choice of the operation parameters, selective excitation of oscillation from the fourth to the ninth harmonic of the electron cyclotron resonance can be achieved with kW-level output power from 230 GHz to 465 GHz. By enabling the high-harmonics operation, the required external magnetic field strengths are reduced to the range between 2.6 T to 3.1 T. The parameter variation study is also performed to provide a general conclusion of the high-harmonic LOGs operation. Thirdly, this thesis presents the investigation of a quasi-optical output system for a fourth-harmonic gyro-multiplier in the THz band. A dual-harmonic quasi-optical mode converter (DQMC) and a frequency selective surface (FSS) are employed within this system. It is shown that the optimal design of the DQMC requires a special mode selection in the gyro-multiplier. The high-pass FSS is designed, fabricated and experimentally verified by a THz-TDS system. It is demonstrated that the designed FSS is capable of handling the high-power output from the gyro-multiplier.
13

Conception et évaluation des performances d'un microgyromètre vibrant triaxial en GaAS à structure plane / Conception and performances evaluation of a GaAS planar triaxial vibrating rate microgyro

Roland, Iännis 04 July 2012 (has links)
Cette thèse présente la conception d'un microgyromètre MEMS triaxial. Les microgyromètres ont de nombreuses applications telles que le contrôle d'attitude de drones ou l'interfaces homme/machine. Les microgyromètres triaxiaux sont particulièrement avantageux car ils permettent de déterminer les trois composantes de la vitesse de rotation à partir d'un seule structure monolithique et planaire. Le principe de fonctionnement des gyromètres vibrants à effet Coriolis (CVG) a été étudié analytiquement, puis une structure originale de gyromètre triaxial monolithique et planaire a été conçue. Cette structure est constituée de quatre poutres encastrées sur un cadre déformable. Des prototypes en silicium ont été réalisés et caractérisés. L’arséniure de gallium (GaAs) a été sélectionné pour la réalisation en raison de ses propriétés piézoélectriques et de son fort potentiel de miniaturisation. Un système d’électrodes pour l'excitation et la détection des vibrations mécaniques a été mis au point. Deux procédés d'usinage du GaAs ont été développés, un procédé de gravure chimique et un procédé de gravure plasma permettant tous les deux de graver verticalement le GaAs sur 450 micromètres de profondeur. Le procédé de gravure plasma est compatible avec la réalisation du CVG triaxial. Des résonateurs de test en GaAs dopé Carbone ont été réalisés par gravure chimique pour mesurer l'évolution en température de la résistivité et des propriétés électromécaniques de ce matériau. Ces mesures ont permis d'estimer que les marches aléatoires angulaires du CVG triaxial sont inférieures à 0,025 degré par racine d'heure sur la gamme de température [-40°C +80°C] pour les trois axes de mesure. Ceci situe le potentiel du CVG triaxial conçu parmi les CVG MEMS les plus performants. / This PhD present the conception of a triaxial MEMS microgyro. Microgyros offer a wide range of applications varying from drones attitude control to human interface devices. The triaxial microgyros offer great benefits because they allow determination of the three rotation rate components with only one monolithic planar structure. The operating principle of Coriolis Vibrating Gyro (CVG) has been studied analytically and an original structure has been designed. This structure consists of four beam clamped into a deformable frame. Some silicon prototypes have been machined and characterised. The gallium arsenide (GaAs) has been chosen for the realisation because of its piezoelectric properties and its great miniaturization potential. A transduction system based on GaAs piezoelectricity was developed. Two GaAs machining processes have been developed: a chemical etching process and a plasma etching process which both enable 450 micrometers deep vertical etching. The plasma etching technique allows high fidelity enough machining to be compatible with the triaxial CVG realisation. Some C-doped GaAs test resonators have been realised to measure the resistivity temperature dependency and electromechanical properties of this material. Those characterisations lead to estimate the angular random walk for the three axis ranges below 0,025 degree per square root hour on the temperature range [-40°C +80°C]. This sets the triaxial CVG together with the best monoaxial MEMS CVG.
14

Balanserande robot / Balancing Robot

Nilsson, Fredrik January 2010 (has links)
<p>Denna rapport behandlar utveckling av en tvåhjulig balanserande robot. En PID-regulator är implementerad i en mikrokontroller, som även AD-omvandlar en sensorsignal, samt styr motorer via H-bryggor med pulsbreddsmodulering. I rapporten förklaras framtagning av diskret PID-regulator, processorkort, motorkort, val av komponenter och sensor för att mäta robotens vinkel mot ett vertikalplan.</p><p>Roboten kan balansera stillastående, men behöver kompletteras ytterligare med hjulåterkoppling för att kunna balansera medan den kör. Roboten balanserar med mätdata från en mekanisk golvavkännare (potentiometer). Andra sorters sensorer diskuteras också, t ex accelerometer, gyro och optisk sensor.</p> / <p>This report explain the development of a two wheel balancing robot. A PID-regulator is implemented in a microcontroller, which also AD-converts a sensor signal, and generate pulse width modulated signals to drive H-bridges. It is discussed how to develop a discretisized PID regulator, microcontroller and H-bridge circuit boards, as well as how to chose components and suitable sensors for measuring the robots angle against a vertical plane.</p><p>The robot is able to balance on its own when standing still, but it need to have feedback from its wheel position if it should be able to maintain balancing when moving. The robot use a mechanical floor feeler (potentiometer). Other sensors are also discussed, e g accelerometer, rate gyro and optical sensor.</p>
15

Konstruktion och reglering av flygande plattform

Waldsjö, Jonathan January 2010 (has links)
<p>This report describes the manufacture and control of a flying platform. The report describes the basic and fundamental theories required to get the platform flying. It touches on subjects such as A/D-conversion. PWM-control and PID-control. The sensors used in the platform are a gyro and an accelerometer. The platform is controlled from a ground station through a wireless link. The wireless link is an Xbee-module that implements the ZigBee-protocol. The microprocessor used is the Atmega 128 by Atmel.</p><p>An indirect complementary filter is used to get the angle of the platform. For the platform to be able to balance a more thourough analysis of the gyro is required. This sensor proved to be more difficult to handle than first anticipated. Every component except the gyro worked as expected. Every algorithm and method reported in this work have been implemented and tested in software.</p>
16

Balanserande robot / Balancing Robot

Nilsson, Fredrik January 2010 (has links)
Denna rapport behandlar utveckling av en tvåhjulig balanserande robot. En PID-regulator är implementerad i en mikrokontroller, som även AD-omvandlar en sensorsignal, samt styr motorer via H-bryggor med pulsbreddsmodulering. I rapporten förklaras framtagning av diskret PID-regulator, processorkort, motorkort, val av komponenter och sensor för att mäta robotens vinkel mot ett vertikalplan. Roboten kan balansera stillastående, men behöver kompletteras ytterligare med hjulåterkoppling för att kunna balansera medan den kör. Roboten balanserar med mätdata från en mekanisk golvavkännare (potentiometer). Andra sorters sensorer diskuteras också, t ex accelerometer, gyro och optisk sensor. / This report explain the development of a two wheel balancing robot. A PID-regulator is implemented in a microcontroller, which also AD-converts a sensor signal, and generate pulse width modulated signals to drive H-bridges. It is discussed how to develop a discretisized PID regulator, microcontroller and H-bridge circuit boards, as well as how to chose components and suitable sensors for measuring the robots angle against a vertical plane. The robot is able to balance on its own when standing still, but it need to have feedback from its wheel position if it should be able to maintain balancing when moving. The robot use a mechanical floor feeler (potentiometer). Other sensors are also discussed, e g accelerometer, rate gyro and optical sensor.
17

Performance analysis and modeling of GYRO

Lively, Charles Wesley, III 30 October 2006 (has links)
Efficient execution of scientific applications requires an understanding of how system features impact the performance of the application. Performance models provide significant insight into the performance relationships between an application and the system used for execution. In particular, models can be used to predict the relative performance of different systems used to execute an application. Recently, a significant effort has been devoted to gaining a more detailed understanding of the performance characteristics of a fusion reaction application, GYRO. GYRO is a plasma-physics application used to gain a better understanding of the interaction of ions and electrons in fusion reactions. In this thesis, we use the well-known Prophesy system to analyze and model the performance of GYRO across various supercomputer platforms. Using processor partitioning, we determine that utilizing the smallest number of processors per node is the most effective processor configuration for executing the application. Further, we explore trends in kernel coupling values across platforms to understand how kernels of GYRO interact. In this work, experiments are conducted on the supercomputers Seaborg and Jacquard at the DOE National Energy Research Scientific Computing Center and the supercomputers DataStar P655 and P690 at the San Diego Supercomputing Center. Across all four platforms, our results show that utilizing one processor per node (ppn) yields better performance than full or half ppn usage. Our experimental results also show that using kernel coupling to model and predict the performance of GYRO is more accurate than summation. On average, kernel coupling provides for prediction estimates that have less than a 7% error. The performance relationship between kernel coupling values and the sharing of information throughout the GYRO application is explored by understanding the global communication within the application and data locality.
18

Konstruktion och reglering av flygande plattform

Waldsjö, Jonathan January 2010 (has links)
This report describes the manufacture and control of a flying platform. The report describes the basic and fundamental theories required to get the platform flying. It touches on subjects such as A/D-conversion. PWM-control and PID-control. The sensors used in the platform are a gyro and an accelerometer. The platform is controlled from a ground station through a wireless link. The wireless link is an Xbee-module that implements the ZigBee-protocol. The microprocessor used is the Atmega 128 by Atmel. An indirect complementary filter is used to get the angle of the platform. For the platform to be able to balance a more thourough analysis of the gyro is required. This sensor proved to be more difficult to handle than first anticipated. Every component except the gyro worked as expected. Every algorithm and method reported in this work have been implemented and tested in software.
19

Control of a Spacecraft Using Mixed Momentum Exchange Devices

Currie, Blake J 01 October 2014 (has links) (PDF)
Hardware configurations, a control law, and a steering law are developed for a mixed hardware spacecraft that uses both control moment gyros and reaction wheels. Replacing one or more gyros in a spacecraft with a reaction wheel has potential for cost savings while still achieving much greater performance than using reaction wheels alone. Several simulated tests are run to compare the performance to a traditional all reaction wheel or all control moment gyro spacecraft, including analysis of failure modes and singular configurations. The mixed system performed similarly to all gyro systems, responding within 6% of the gyro system’s time for all nominal cases. It far exceeds the performance of reaction wheel systems, taking only a fourth of the time. It also handles failures better than reduced size gyro systems. As such, it can be an effective cost saving measure for certain satellite missions.
20

Posture Positive : konceptdriven designforskning som undersöker spel som en möjlig lösning för ungdomars hållningsproblem / Posture Positive : concept driven design research that examines games as a possible solution to young people’s posture problems

Sandberg, Tanja January 2020 (has links)
Med en ökad användning av digitala enheter i samhället ser vi också att fler drabbas av hållningsrelaterade hälsobekymmer. Ungdomar är särskilt drabbade även om de i många fall är omedvetna om det, men knappt ingen forskning fokuserar på den här målgruppen och deras behov. Den forskning som tagits fram är inte heller överens hur man på bästa sätt löser problematiken med hållning. Syftet med studien är därför att göra ungdomar mer medvetna om sin kroppshållning samt ta reda på hur digital design på bästa sätt kan motivera ungdomar att förbättra sin kroppshållning. För att ta reda på detta ställdes följande fråga: ”Hur kan en digital designlösning utformas för att skapa medvetenhet kring ungdomars kroppshållning, samt hjälpa att förbättra deras kroppshållning på ett underhållande och icke störande sätt?”. Studien genomfördes med metoden Konceptdriven Designforskning som inkluderar skapandet av en konceptuell prototyp förankrad i tidigare forskning. Prototypen består av en bärbar sensor som mäter hållning och en applikation i form av ett spel där användaren kan se sin hållning i realtid samt aktivt träna sin hållning. Prototypen värderades sedan genom en digital enkätundersökning. I resultatet framgick att designlösningen kunde tänkas användas av deltagarna, samt hjälpa att förbättra deras hållning eftersom den gjorde användaren mer medveten om sin kroppshållning. Många deltagare trodde att spelet kunde bidra med motivation och göra hållningsträningen mer underhållande men att fler spel-funktioner krävs för att behålla användarens intresse under en längre tid. Deltagarna ansåg att konceptet i sin helhet inte var störande men att mer tydlig feedback krävs för att indikera bra/dålig hållning. Utifrån detta resultat kan slutsatsen dras att konceptet i teorin kan skapa medvetenhet kring ungdomars kroppshållning och hjälpa de att träna den på ett underhållande sätt som inte är störande, men att mer studier och designarbete krävs för att komma fram till det bästa sättet att ge användaren feedback om sin hållning samt göra konceptet mer attraktivt att använda ur ett långsiktigt perspektiv. / With the increased use of digital devices in society, we can see that more people are affected by posture related health issues. Adolescents are especially affected although in many cases they are unaware of it, but hardly any research focuses on this group and their needs. The research that has been done also does not agree on how to best solve the problem with posture. The purpose of this study is therefore to make young people more aware of their posture and to find out how digital design can be used in the best way to motivate young people to improve their posture. To find this out, the following question was formed: “How can a digital design solution be formed to create awareness about young people's posture and help improve their posture in an entertaining and non-disturbing way”. The study was carried out with the method Concept driven design research which includes the creation of a conceptual prototype grounded in previous research. The prototype consists of a portable sensor that measures posture and an application in the form of a game where the user can see their posture in real time and actively train their posture. The prototype was then evaluated through a digital survey. The results showed that the participants could consider using the design solution and that it helped to improve their posture as it made the user more aware of their posture. Many participants thought that the game could contribute with motivation and make posture training more entertaining, but that more gaming features are required to keep the user's interest for a longer period. The participants felt that the concept as a whole was not disruptive, but that more clear feedback is required to indicate good/bad posture. Based on this result, it can be concluded that the concept in theory can create awareness of young people's posture and help them to exercise it in an entertaining way that is not disturbing, but that further studies and design work is needed to come up with the best way to give the user feedback on their posture and to make the concept more attractive to use from a long-term perspective.

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