The Impact of GPS Velocity Based Flight Control on Flight Instrumentation Architecture

This thesis explores the use of velocity information obtained by a Global Positioning System (GPS) receiver to close the aircraft’s flight control loop. A novel framework to synthesize attitude information from GPS velocity vector measurements is discussed. The framework combines the benefits of high-quality GPS velocity measurements with a novel velocity vector based flight control paradigm to provide a means for the human operator or autopilot to close the aircraft flight control loop. Issues arising from limitations in GPS as well as the presence of a human in the aircraft control loop are addressed. Results from several flight tests demonstrate the viability of this novel concept and show that GPS velocity based attitude allows for equivalent aircraft control as traditional attitude. Two possible applications of GPS velocity based attitude, an autopilot and a tunnelin- the-sky trajectory guidance system, are demonstrated in flight. Unlike traditional autopilot and trajectory guidance systems, these applications rely solely on the information obtained from a single-antenna GPS receiver which makes them affordable to the larger General Aviation aircraft community. Finally, the impact of GPS velocity based flight control on the instrumentation architecture of flight vehicles is investigated.Rockwell-Collins, NASA/FAA Joint University Program for Air Transportation, Draper Laborator

A design methodology for the implementation of embedded vehicle navigation systems

RÉSUMÉ Au fil des années, en raison de l'augmentation de la densité routière et l'intensité de la circulation, un système de navigation automobile devient nécessaire. Ce système doit fournir non seulement l'emplacement du véhicule mais, surtout, augmentera le contrôle, la sécurité et la performance globale de l'automobile. La baisse du coût des récepteurs de Géo-Positionnement par Satellite (GPS) a vulgarisé leur utilisation dans la navigation automobile. Le système GPS fournit les données de positionnement ainsi que l'information qui concerne la vitesse aux conducteurs. De ce fait, la plupart des dispositifs de navigation des automobiles civiles sont actuellement basés sur la technologie GPS. Cependant, en cas de perte du signal GPS par blocage par feuillage, passages en béton, dense agglomération urbaine, grands immeubles, tunnels et dans le cas d'atténuation, ces dispositifs ne parviennent pas à fonctionner avec précision. Une solution alternative au GPS, qui peut être utilisée dans la navigation automobile, est le système de navigation inertielle (INS). LINS est un système autonome qui n'est pas affecté par des perturbations externes. Il comprend des capteurs inertiels comme trois gyroscopes et trois accéléromètres. Le coût des INS peut être faible mais leur performance se détériore à long terme car ils souffrent des erreurs accumulées. Cependant, il peut fournir des solutions précises sur de courts intervalles de temps. Un système intégré de GPS/INS à faible coût a donc le potentiel de fournir de meilleures informations de position pendant des intervalles courts et longs. L'objectif principal de cette recherche était de mettre en place une solution d'un système de navigation véhiculaire temps réel sur une plateforme embarquée à faible coût. Ceci avait pour but de pouvoir l'utiliser comme un cadre de conception, et comme référence pour d'autres applications embarquées similaires. Pour améliorer la solution de navigation même en cas d'arrêt de fonctionnement du GPS, les données du système GPS/INS ont été fusionnées par la technique de la boucle fermée du filtrage de Kalman décentralisé en utilisant 15 équations d'états d'erreurs d'ENS. En raison de l'utilisation d'accéléromètre à faible coût, ainsi que des capteurs gyroscopiques de données, une technique de prétraitement nommée algorithme de débruitage par ondelettes a été adoptée. L'algorithme a un maximum de 5 niveaux de décomposition, de reconstruction, ainsi que du seuillage non linéaire à chaque niveau. La conception est décrite par un logiciel qui comprend un microprocesseur embarqué. L'implémentation est effectuée à l'aide d'un cœur du processeur MicroBlaze qui gère le processus de contrôle et exécute l'algorithme. Afin de développer une implémentation efficace, des calculs en virgule flottante sont effectués en utilisant l'unité de virgule flottante (FPU) du cœur du processeur Microblaze. Le système est implémenté sur carte FPGA Spartan-3 de Xilinx. Elle contient 200 mille portes logiques cadencées par un oscillateur à 50 MHz, avec une mémoire externe asynchrone SRAM de 1 Mio. Le système comprend également un bus périphérique sur puce (OPB). À ce titre, la solution finale du système de navigation automobile devrait avoir des caractéristiques telles qu'une faible consommation de puissance, un poids léger, une capacité de traitement en temps réel ainsi qu'un petit espace occupé sur puce. D'un point de vue développement, l'utilisation du langage C et d'un cœur de processeur fonctionnant sur FPGA donne à l'utilisateur une plateforme flexible pour tout prototypage d'applications. Les simulations montrent qu'une implémentation purement logicielle de l'algorithme de la boucle fermée du filtrage de Kalman décentralisé sur une plateforme embarquée qui utilise les nombres virgule-flottante à simple précision, peut produire des résultats acceptables. Ceci est conforme aux résultats obtenus sur une plateforme d'un ordinateur de bureau qui utilise les nombres virgule-flottante à double précision. Dans un premier temps, le code du filtrage de Kalman est exécuté à partir d'une mémoire externe SRAM de 1 Mio, soutenue par une mémoire cache de données de 8Kio et une cache d'instructions de 4 Kio. Puis, le même code est lancé à partir du bloc RAM sur puce, à grande vitesse, de 64 Kio. Dans les deux configurations mémoire, les fréquences d'échantillonnage maximales pour lesquelles le code peut être exécuté sont de 80 Hz (période de 12,5 ms) et 119 Hz (période de 8,4 ms), respectivement, tandis que les capteurs fournissent les données à 75 Hz Les même deux configurations de mémoire sont employées dans l'exécution de l'algorithme de débruitage par ondelettes avec 5 niveaux de décomposition, de reconstruction et seuillage non linéaire à chaque niveau. Sur l'accéléromètre et le gyro, les données brutes sont fournies en temps réel en utilisant un mode de fenêtre de non-chevauchement, avec une longueur de fenêtre de 75 échantillons. Les latences d'exécution dans les deux cas sont 5,47 ms et 1,96 ms pour les deux configurations de mémoire précédemment citées, respectivement. En outre, l'analyse temporelle de !'après synthèse des deux configurations matérielles, reporte des apports de 26% et 66% respectivement. Puisque le système fonctionne à 50 MHz, il y a ainsi une marge de manœuvre disponible intéressante pour des perfectionnements algorithmiques. Ainsi, en utilisant la combinaison d'une plate-forme peu coûteuse, une approche flexible de développement et une solution en temps réel, l'exécution montrée dans ce mémoire démontre que la synthèse d'une solution finale de navigation véhiculaire fonctionnant en temps réel, complètement fonctionnelle, panne-résiliente, peu coûteuse est faisable. -------------------ABSTRACT Over the years, due to the increasing road density and intensive road traffic, the need for automobile navigation has increased not just for providing location awareness but also for enhancing vehicular control, safety and overall performance. The declining cost of Global Positioning System (GPS) receivers has rendered them attractive for automobile navigation applications. GPS provides position and velocity information to automobile users. As a result, most of the present civilian automobile navigation devices are based on GPS technology. However, in the event of GPS signal loss, blockage by foliage, concrete overpasses, dense urban developments viz. tall buildings or tunnels and attenuation, these devices fail to perform accurately. An alternative to GPS that can be used in automobile navigation is an Inertial Navigation System (INS). INS is a self-contained system that is not affected by external disturbances. It comprises inertial sensors such as three gyroscopes and three accelerometers. Although low-grade, low-cost INS performance deteriorates in the long run as they suffer from accumulated errors, they can provide adequate navigational solution for short periods of time. An integrated GPS/INS system therefore has the potential to provide better positional information over short and long intervals. The main objective of this research was to implement a real-time navigation system solution on a low cost embedded platform so that it can be used as a design framework and reference for similar embedded applications. An integrated GPS/INS system with closed loop decentralized Kalman filtering technique is designed using trajectory data from low-cost GPS, accelerometer and gyroscope sensors. A data pre-processing technique based on a wavelet de-noising algorithm is implemented. It uses up to five levels of de-composition and reconstruction with non-linear thresholding on each level. The design is described in software which consists of an embedded microprocessor namely MicroBlaze that manages the control process and executes the algorithm. In order to develop an efficient implementation, floating-point computations are carried out using the floating point unit (FPU) of MicroBlaze soft core processor. The system is implemented on a Xilinx Spartan-3 Field Programmable Gate Array (FPGA) containing 200 thousand gates clocked by an onboard oscillator operating at 50 MHz, with an external asynchronous SRAM memory of 1 MiB. The system also includes the IBM CoreConnect On-Chip Peripheral Bus (OPB). As such the final solution for vehicle navigation system is expected to have features like low power consumption, light weight, real-time processing capability and small chip area. From a development point of view, the combination of the standard C programming language and a soft processor running on an FPGA gives the user a powerful yet flexible platform for any application prototyping. Results show that a purely software implementation of the decentralized closed loop Kalman filter algorithm embedded platform that uses single precision floating point numbers can produce acceptable results relative to those obtained from a desktop PC platform that uses double precision floating point numbers. At first, the Kalman filter code is executed from a 1 MiB external SRAM supported by 8KiB of data cache and 4IUB of instruction cache. Then, the same code is run from high speed 64ICiB on-chip Block RAM. In the two memory configurations, the maximum sampling frequencies at which the code can be executed are 80 Hz (period of 12.5 ms) and 119 Hz (period of 8.4 ms) respectively, while accelerometer and gyroscope sensors provide data at 75 Hz. The same two memory configurations are employed in executing a wavelet de-noising algorithm with 5 levels of de-composition, reconstruction and non linear thresholding on each level. Accelerometer and gyroscope raw data are processed in real-time using non-overlapping windows of 75 samples. The execution latencies in the two cases are found to be 5.47 ms and 1.96 ms respectively. Additionally, from the post synthesis timing analyses, the critical frequencies for the two hardware configurations were 63.3 MHz and 83.2 MHz. an enhancement of 26% and 66% respectively. Since the system operates at 50 MHz, there is thus an interesting processing margin available for further algorithmic enhancements. Thus, by employing the combination of a low cost embedded platform, a flexible development approach and a real-time solution, the implementation shown in this thesis demonstrates that synthesizing a completely functional low-cost, outage-resilient, real-time navigation solution for automotive applications is feasible. -------------CONTENT Automobile Navigation -- Global Positioning System -- Navigation Frame -- Earth Models -- Attitude Representations -- Inertial Navigation System -- IMU Sensor Errors -- 2D INS Mechanization Equations -- 3D INS Mechanization Equations -- INS Error Equations -- GPS/INS data fusion using KF -- IMU data prepocessing using Wavelet De-noising -- Hardware/Equipment Setup -- Embedded Platform -- Hardware Platform Development -- Software Coding -- Software Design Issues -- Navigation Solution using MicroBlaze -- Timing Measurements

Development of a model helicopter based flight test platform for multivariable feedback control.

M. Sc. Eng. University of KwaZulu-Natal, Durban 2009.The dissertation describes the development of a model helicopter based flight test platform for implementing autonomous six degree of freedom flight by a multiple input multiple output automatic control system. The focus of the research is two fold: i. Navigation system design centred about fusing multiple data and measurement sources using Kalman filtering techniques. ii. Electrical engineering of a complete avionics package to support guidance, navigation and control functions. Included are the results from several experiments conducted on the test platform, highlighting salient aspects and performance of the electrical and navigation systems.Appendices could not be converted to pdf and uploaded to ResearchSpace. Appendices found on a separate disc accompanying print copy

Feasibility study: Electronic media laboratory according to Industry standard

The goal of this Master's thesis was to find out the Metropolia media technology laboratory’s correlation to industrial electronic media production standards and environments. The laboratory environment for education and training should be following not only media technology curriculum, but also the requirements set for learning audio-visual technology, including the processes, technologies and practices involved in professional electronic production and publishing in Finland. Since the role of the laboratory is to perform as an effective learning environment, there are some understandable restrictions in technology and development, in financial and in management section that prevent it from reaching the industrial level. These limitations and differences between this environment and more sophisticated industrial model were studied in this thesis. Feasibility study, which is suitable for analyzing the technology, financial and administrative development all together, was selected as the research method. The study was intended to determine the achievable laboratory model of functional validation and also to demonstrate the proof of concept. Audiovisual production in the laboratory and the subsequent electronic digital publishing was created as an embedded model. The model takes into account the ongoing changes in the television environment and the traditional radio frequency transmission, which is now competing with other alternatives such as IP network distribution. Video editing as post production was analyzed in its current state and compared to a complete network-based-editing NAS and SAN model, which can also be implemented in cloud technologies for decentralized co-operation. This way the model was following the industry trends and future prospects. Research material was collected and acquired from written sources, industry fairs and conferences, resellers and agents as well as production companies and broadcasters. Practical implementation of electronic media publishing was simulated in the laboratory environment so that all the possible reception technologies were covered. Publishing was customized for compatibility with various devices. Noteworthy aspects in this publishing process were the post-processing, packetizing and distribution related quality management aspects their definition and management issues were also discussed in this thesis. The end result was a feasibility analysis and model, which defines the electronic publishing technology teaching bottlenecks regarding the equivalence of the technologies in laboratory environment.YAMK-insinöörityön tavoitteena oli selvittää Metropolian mediatekniikan laboratorion vastaavuus teollisessa elektronisen median tuotannossa noudatettaviin standardeihin. Laboratorion koulutusympäristönä tulee noudattaa paitsi mediatekniikan opetussuunnitelmassa audio-visuaaliselle tekniikalle oppimiselle asetettuja vaatimuksia, myös niitä prosesseja, käytäntöjä ja teknologioita joita ammattimainen elektroninen tuotanto ja julkaiseminen Suomessa toteuttaa. Oppimisympäristönä toimivan laboratorion kehittämiselle ja varustamiselle on ymmärrettävästi teknisiä, taloudellisia ja hallinnallisia rajoituksia, jotka estävät sen saavuttamasta teollista tasoa. Näiden rajojen ja kehittyneemmän teollisen mallin eroja tutkittiin. Tutkimusmenetelmäksi valittiin saavutettavuustutkimus (eng. feasebility study), joka menetelmänä soveltuu teknologian, taloudellisen tai hallinnollisen kehittämiseen analysointiin. Tutkimuksella pyrittiin määrittelemään saavutettavissa olevan laboratoriomallin toiminnallinen validointi ja toteutettavuuden osoitus (engl.proof of concept). Laboratorion audiovisuaalista tuotantoa ja sitä seuraavaa elektronista sekä digitaalista julkaisemista varten luotiin sulautettu malli. Mallissa huomioitiin televisioympäristössä meneillään oleva muutos, jossa perinteinen radiotaajuuslähettäminen on saanut vaihtoehdoksi IP- verkoilla suoritettavan jakelun. Videon editointi jälkituotantona analysointiin nykytilassa ja vertailtiin sitä täydellisen verkkoeditoinnin malleihin, jotka voivat myös toteuttaa pilviteknologioita hajautetussa tuotannollisessa yhteistyössä. Näin medialaboratorion mallinnuksessa huomioitiin toimialan ajan trendit ja tulevaisuuden näkymät. Tämä tutkimusaineisto hankittiin kirjallisten lähteiden lisäksi, alan messuilta ja konferensseista, maahantuojilta ja edustajilta sekä tuotanto- ja yleisradioyhtiöiltä. Elektronisen median julkaisemista simuloitiin laboratorioympäristössä niin, että kaikki mahdolliset vastaanottotekniikat oli otettu huomioon. Julkaiseminen räätälöitiin myös soveltuvaksi eri päätelaitteille. Julkaisemisessa huomionarvoisiksi asioiksi nousivat audiovisuaalisen sisällön jälkiprosessointiin, paketointiin ja lähettämiseen liittyvät tekniset laadunhallinnan aspektit, esimerkiksi eri videonpakkausalgoritmien soveltuvuus videosisällön jakelussa, julkaisemisen automatisoinnin mahdollistaminen ja eri julkaisualustojen tutkiminen ja määrittely Lopputuloksena saatiin aikaan soveltuvuusanalyysi ja mallinnus, jossa määriteltiin elektronisen julkaisemisen teknisen opetuksen pullonkaulat teolliseen vastaavuuteen nähden. Suurimmaksi kompastuskiveksi voidaan mainita jakelujärjestelmän operoinnin hankaluus sekä verkotetun editointijärjestelmän määrittelyn haasteellisuus

Interferometric synthetic aperture sonar system supported by satellite

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 200

Generic Multisensor Integration Strategy and Innovative Error Analysis for Integrated Navigation

A modern multisensor integrated navigation system applied in most of civilian applications typically consists of GNSS (Global Navigation Satellite System) receivers, IMUs (Inertial Measurement Unit), and/or other sensors, e.g., odometers and cameras. With the increasing availabilities of low-cost sensors, more research and development activities aim to build a cost-effective system without sacrificing navigational performance. Three principal contributions of this dissertation are as follows: i) A multisensor kinematic positioning and navigation system built on Linux Operating System (OS) with Real Time Application Interface (RTAI), York University Multisensor Integrated System (YUMIS), was designed and realized to integrate GNSS receivers, IMUs, and cameras. YUMIS sets a good example of a low-cost yet high-performance multisensor inertial navigation system and lays the ground work in a practical and economic way for the personnel training in following academic researches. ii) A generic multisensor integration strategy (GMIS) was proposed, which features a) the core system model is developed upon the kinematics of a rigid body; b) all sensor measurements are taken as raw measurement in Kalman filter without differentiation. The essential competitive advantages of GMIS over the conventional error-state based strategies are: 1) the influences of the IMU measurement noises on the final navigation solutions are effectively mitigated because of the increased measurement redundancy upon the angular rate and acceleration of a rigid body; 2) The state and measurement vectors in the estimator with GMIS can be easily expanded to fuse multiple inertial sensors and all other types of measurements, e.g., delta positions; 3) one can directly perform error analysis upon both raw sensor data (measurement noise analysis) and virtual zero-mean process noise measurements (process noise analysis) through the corresponding measurement residuals of the individual measurements and the process noise measurements. iii) The a posteriori variance component estimation (VCE) was innovatively accomplished as an advanced analytical tool in the extended Kalman Filter employed by the GMIS, which makes possible the error analysis of the raw IMU measurements for the very first time, together with the individual independent components in the process noise vector

Safe navigation for vehicles

La navigation par satellite prend un virage très important ces dernières années, d'une part par l'arrivée imminente du système Européen GALILEO qui viendra compléter le GPS Américain, mais aussi et surtout par le succès grand public qu'il connaît aujourd'hui. Ce succès est dû en partie aux avancées technologiques au niveau récepteur, qui, tout en autorisant une miniaturisation de plus en plus avancée, en permettent une utilisation dans des environnements de plus en plus difficiles. L'objectif aujourd'hui est de préparer l'utilisation de ce genre de signal dans une optique bas coût dans un milieu urbain automobile pour des applications critiques d'un point de vue sécurité (ce que ne permet pas les techniques d'hybridation classiques). L'amélioration des technologies (réduction de taille des capteurs type MEMS ou Gyroscope) ne peut, à elle seule, atteindre l'objectif d'obtenir une position dont nous pouvons être sûrs si nous utilisons les algorithmes classiques de localisation et d'hybridation. En effet ces techniques permettent d'avoir une position sans cependant permettre d'en quantifier le niveau de confiance. La faisabilité de ces applications repose d'une part sur une recherche approfondie d'axes d'amélioration des algorithmes de localisation, mais aussi et conjointement, sur la possibilité, via les capteurs externes de maintenir un niveau de confiance élevé et quantifié dans la position même en absence de signal satellitaire. ABSTRACT : Satellite navigation has acquired an increased importance during these last years, on the one hand due to the imminent appearance of the European GALILEO system that will complement the American GPS, and on the other hand due to the great success it has encountered in the commercial civil market. An important part of this success is based on the technological development at the receiver level that has rendered satellite navigation possible even in difficult environments. Today's objective is to prepare the utilisation of this kind of signals for land vehicle applications demanding high precision positioning. One of the main challenges within this research domain, which cannot be addressed by classical coupling techniques, is related to the system capability to provide reliable position estimations. The enhancement in dead-reckoning technologies (i.e. size reduction of MEMS-based sensors or gyroscopes) cannot all by itself reach the necessary confidence levels if exploited with classical localization and integration algorithms. Indeed, these techniques provide a position estimation whose reliability or confidence level it is very difficult to quantify. The feasibility of these applications relies not only on an extensive research to enhance the navigation algorithm performances in harsh scenarios, but also and in parallel, on the possibility to maintain, thanks to the presence of additional sensors, a high confidence level on the position estimation even in the absence of satellite navigation signals

Applications in Low-Power Phased Array Weather Radars

Low-cost X-band radars are an emerging technology that offer significant advantages over traditional systems for weather remote sensing applications. X-band radars provide enhanced angular resolution at a fraction of the aperture size compared to larger, lower frequency systems. Because of their low cost and small form factor, these radars can now be integrated into more research and commercial applications. This work presents research and development activities using a low-cost, X-band (9410 MHz) Phase-Tilt Radar. The phase-tilt design is a novel phased array architecture that allows for rapid electronic scanning in azimuth and mechanical tilting in elevation, as a compromise between cost and performance. This work focuses on field studies and experiments in three meteorological applications. The first stage of research focuses on the real-world application of phased array radars in forest fire monitoring and observation. From April to May 2013, a phase-tilt radar was deployed to South Australia and underwent a field campaign to make polarimetric observations of prescribed burns within and around the Adelaide Hills region. Measurements show the real-time evolution of the smoke plume dynamics at a spatial and temporal resolution that has never before been observed with an X-band radar. This dissertation will perform data analysis on results from this field campaign. Results are compared against existing work, theories, and approaches. In the second stage of research, field experiments are performed to assess the data quality of X-band phased array radars. Specifically, this research focuses on the measurement of and techniques to improve the variance of weather product estimators for dual-polarized systems. Variability in the radar products is a complicated relationship between the radar system specifications, scanning strategy, and the physics governing precipitation. Here, the variance of the radar product estimators is measured using standard radar scanning strategies employed in traditional mechanical antenna systems. Results are compared against adaptive scan strategies such as beam multiplexing and frequency diversity. This work investigates the improvement that complex scanning strategies offer in dual-polarized, X-band phased array radar systems. In the third stage of research, simulations and field experiments are conducted to investigate the performance benefits of adaptive scanning to optimize the data quality of radar returns. This research focuses on the development and implementation of a waveform agile and adaptive scanning strategy to improve the quality of weather product estimators. Active phased array radars allow radar systems to quickly vary both scan pointing angles and waveform parameters in response to real-time observations of the atmosphere. As an evolution of the previous research effort, this work develops techniques to adaptively change the scan pointing angles, transmit and matched filter waveform parameters to achieve a desired level of data quality. Strategies and techniques are developed to minimize the error between observed and desired data quality measures. Simulation and field experiments are performed to assess the quality of the developed strategies

Advances in Sonar Technology

The demand to explore the largest and also one of the richest parts of our planet, the advances in signal processing promoted by an exponential growth in computation power and a thorough study of sound propagation in the underwater realm, have lead to remarkable advances in sonar technology in the last years.The work on hand is a sum of knowledge of several authors who contributed in various aspects of sonar technology. This book intends to give a broad overview of the advances in sonar technology of the last years that resulted from the research effort of the authors in both sonar systems and their applications. It is intended for scientist and engineers from a variety of backgrounds and even those that never had contact with sonar technology before will find an easy introduction with the topics and principles exposed here