A navigation filter simulation and analysis environment was developed through the integration of DRAGON, a high fidelity real-time PNT sensor measurement source, and Scorpion, a modular navigation filter implementation framework. The envi- ronment allows navigation filters to be prototyped and tested in varying complex scenarios with a configurable set of navigation sensors including GNSS and IMU. An analysis of an EKF using the environment showed the utility and functionality of the system.

A navigation filter simulation and analysis environment was developed through the integration of DRAGON, a high fidelity real-time PNT sensor measurement source, and Scorpion, a modular navigation filter implementation framework. The envi- ronment allows navigation filters to be prototyped and tested in varying complex scenarios with a configurable set of navigation sensors including GNSS and IMU. An analysis of an EKF using the environment showed the utility and functionality of the system.

Giving robots the ability to move around autonomously in various real-world environments has long been a major challenge for Artificial Intelligence. New approaches to the design and control of autonomous robots have shown the value of drawing inspiration from the natural world. Animals navigate, perceive and interact with various uncontrolled environments with seemingly little effort. Flying insects, in particular, are quite adept at manoeuvring in complex, unpredictable and possibly hostile environments.Inspired by the miniature machine view of insects, this thesis contributes to the autonomous control of mobile robots through the application of insect-based visual cues and behaviours. The parsimonious, yet robust, solutions offered by insects are directly applicable to the computationally restrictive world of autonomous mobile robots. To this end, two main navigational domains are focussed on: corridor guidance and visual homing.Within a corridor environment, safe navigation is achieved through the application of simple and intuitive behaviours observed in insect, visual navigation. By observing and responding to observed apparent motions in a reactive, yet intelligent way, the robot is able to exhibit useful corridor guidance behaviours at modest expense. Through a combination of both simulation and real-world robot experiments, the feasibility of equipping a mobile robot with the ability to safely navigate in various environments, is demonstrated.It is further shown that the reactive nature of the robot can be augmented to incorporate a map building method that allows previously encountered corridors to be recognised, through the observation of landmarks en route. This allows for a more globally-directed navigational goal.Many animals, including insects such as bees and ants, successfully engage in visual homing. This is achieved through the association of ++ / visual landmarks with a specific location. In this way, the insect is able to 'home in' on a previously visited site by simply moving in such a way as to maximise the match between the currently observed environment and the memorised 'snapshot' of the panorama as seen from the goal. A mobile robot can exploit the very same strategy to simply and reliably return to a previously visited location.This thesis describes a system that allows a mobile robot to home successfully. Specifically, a simple, yet robust, homing scheme that relies only upon the observation of the bearings of visible landmarks, is proposed. It is also shown that this strategy can easily be extended to incorporate other visual cues which may improve overall performance.The homing algorithm described, allows a mobile robot to home incrementally by moving in such a way as to gradually reduce the discrepancy between the current view and the view obtained from the home position. Both simulation and mobile robot experiments are again used to demonstrate the feasibility of the approach.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Einleitung Die Navigation in der Nasennebenhöhlenchiurgie hat bereits Einzug in den klinischen Alltag gehalten. Zur Evaluierung ihrer Leistungsfähigkeit bedarf es der Überprüfung der chirurgischen Genauigkeit am Patienten. Die Durchführung einer Genauigkeitsstudie am Patienten ist aus ethischen und methodischen Gründen nicht zu realisieren. Eine Phantomstudie soll eine realistische und ausführliche Genauigkeitsstudie ermöglichen. Besonderes Augenmerk wird in dieser Studie auf die Registrierung gelegt. Material und Methoden Gegenstand der Untersuchungen ist ein optoelektrisches Navigationssystem der Firma Karl Storz (NPU). Zur Evaluierung der Auswirkung der Registrierung auf die Navigationsgenauigkeit wurden die Registrierungspunkte in verschiedenen Mustern angeordnet. Es wurde das Registrierungsmuster der Standardregistrierung zwei weiteren gegenübergestellt. Zum einen wurden die Registrierungspunkte enger und zum anderen weiter gesetzt. Es standen zwölf HNO-ärztliche Probanden zur Verfügung. Die Aufgabe bestand darin, insgesamt zehn mit einer Titanschraube markierten Landmarken unter endoskopischer Kontrolle mit der Pointerspitze zu berühren. Die korrespondierenden Koordinaten wurden dokumentiert. Durch eine Vektorrechnung wird die Abweichung vom Soll- und Ist-Wert berechnet. Ergebnisse Es konnten insgesamt 1800 gültige Messdaten für die Abweichung aus 5400 Koordinaten ermittelt werden. Die Ergebnisse sind überwiegend normalverteilt. Die durchschnittliche Genauigkeit für die Standardregistrierung betrug 3,51 mm bei einer Präzision von 1,17 mm und einer maximalen Abweichung bis 5,87 mm. Für die Registrierung mit dem größeren Volumen konnte eine chirurgische Genauigkeit ermittelt werden von 3,43 mm mit einer Präzision von 0,83 mm und maximalen Abweichung von 4,78 mm. Für die Registrierung mit dem betrug die chirurgische Genauigkeit 4,15 mm, die Präzision 1,55 mm und die maximale Abweichung 7,11 mm. Schlussfolgerungen Die vorliegende Studie konnte zeigen, dass mit der derzeit durchgeführten Standardregistrierung ausreichende, konstante und zuverlässige Navigationsgenauigkeiten erzielt werden können. Es konnten keine signifikanten Unterschiede zur Registrierung mit dem größeren Volumen, jedoch zur Registrierung mit dem kleineren Volumen, nachgewiesen werden. Die Navigationsgenauigkeit ist keine konstante Größe. Die Genauigkeit variiert nach Lage der anatomischen Struktur, abhängig davon, ob sie im Zentrum der Referenzpunkte liegt. Es konnte gezeigt werden, dass über die Qualität der Registrierung Einfluss auf die Navigationsgenauigkeit genommen werden kann. Desweiteren kann von einer Abhängigkeit vom Anwender ausgegangen werden. Hier sind jedoch weiterführende Untersuchungen mit größeren Probandenzahlen erforderlich. Die in dieser Studie erzielten Ergebnisse sind mit Angaben anderer Studien vergleichbar.

Proefschrift--Leiden--Universiteit, 2007. / Bibliogr. p. 303-316. Index. Résumé en anglais.

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The existing air navigation services have many shortcomings and a reform was necessary. The new systems (CNS/ATM systems) will be largely dependent on Global Navigation Satellite Systems (GNSS) which can bring significant benefits to air navigation in terms of safety, efficiency, capacity, and economy. However, GNSS have weaknesses which can be reduced but will never be fully eliminated. Depending solely on a system that can be disrupted is not acceptable for safety of life applications, such as aviation. The implementation of GNSS also raises unique legal issues and ICAO has been working on the establishment of a legal framework for GNSS since 1992. Nevertheless, disagreement between states on the need for an international convention remains significant. Legal discussions should not slow down the implementation of GNSS which, when used in conjunction with terrestrial navigation aids, have the potential to revolutionize air navigation.

The Global Navigation Satellite System (GNSS) is the main element of the CNS/ATM system elaborated by the International Civil Aviation Organization (ICAO). / The US GPS and Russian GLONASS are the two existing systems. Both of them were created by the military. / Europe is currently developing a civil navigation satellite system: Galileo. / This thesis will present some legal issues of the GNSS discussed in the framework of ICAO: sovereignty of States, universal accessibility, continuity and quality of the service, cost recovery and financing, certification and liability. / It will also present some legal issues due to the creation of the European Galileo program. The financing, organizational framework, certification and liability will be examined. Finally, ICAO's Charter on the Rights and Obligations of States Relating to GNSS Services will be considered.

For people with motor disabilities unable to control a pointing device, there is a need for an efficient keyboard Web navigation method. The current state of keyboard navigation tools is surveyed and discussed. The standard tab key navigation system is widely regarded as insufficient for practical keyboard access to the Web. Other techniques, such as identifier navigation --- where links are activated by entering their numeric code --- are found to be much more efficient, but possibilities remain for improvement. A technique based on selecting links by text search provides an alternative method of keyboard navigation, but does not minimize the number of required keyboard inputs, which is important for individuals not capable of fast typing input. A new technique called KeySurf is proposed, which aims to make text search navigation more efficient and intuitive by estimating which elements are more likely to be selected by the user, and then allowing those elements to be selected with fewer keystrokes. Web page elements without text associated with them are assigned labels based on algorithms that make generated labels predictable to the user. Various constraints on the searching algorithm are implemented to decrease the keystroke cost of selections, such as selecting visible elements first, matching the first characters of labels, and prioritizing visually prominent elements. In addition, the user's browsing history is used to calculate a measure of page and element interest in order to make interesting elements easier to select. KeySurf performance is examined in three experiments: an automated analysis of keystroke cost of element selection on randomly selected Web pages, a small study involving four individuals with motor disabilities to compare KeySurf and mouse use, and a study of 11 individuals browsing the Web with KeySurf collecting data passively in the background. The automated selection test calculates the number of keys necessary to activate each link for 48,182 links, resulting in a mean of 2.69 keystrokes. The study involving individuals with disabilities shows that KeySurf can be faster than mouse use if the user is able to type 2 or 3 keystrokes faster than pointing to a target using their pointing device. The study with 11 non-disabled individuals shows that for 4,601 recorded clicks, KeySurf would have required 2.38 keys per selection. Comparing mean keystroke cost for pages containing similar numbers of elements, we find that for real Web sessions KeySurf can decrease keystroke cost by 15\% compared to the simulation results by anticipating which elements a user is likely to select. A keystroke level model of tabbing, ID navigation, and KeySurf indicates that the predictability of ID navigation makes it more efficient for faster typists, while KeySurf is likely to be faster for slower typists. / Graduate