Humans and animals alike use the sun, the moon, and the stars to guide their ways. However, the position of celestial cues changes depending on daytime, season, and place on earth. To use these celestial cues for reliable navigation, the rotation of the sky has to be compensated. While humans invented complicated mechanisms like the Antikythera mechanism to keep track of celestial movements, animals can only rely on their brains. The desert ant Cataglyphis is a prime example of an animal using celestial cues for navigation. Using the sun and the related skylight polarization pattern as a compass, and a step integrator for distance measurements, it can determine a vector always pointing homewards. This mechanism is called path integration. Since the sun’s position and, therefore, also the polarization pattern changes throughout the day, Cataglyphis have to correct this movement. If they did not compensate for time, the ants’ compass would direct them in different directions in the morning and the evening. Thus, the ants have to learn the solar ephemeris before their far-reaching foraging trips. To do so, Cataglyphis ants perform a well-structured learning-walk behavior during the transition phase from indoor worker to outdoor forager. While walking in small loops around the nest entrance, the ants repeatedly stop their forward movements to perform turns. These can be small walked circles (voltes) or tight turns about the ants’ body axes (pirouettes). During pirouettes, the ants gaze back to their nest entrance during stopping phases. These look backs provide a behavioral read-out for the state of the path integrator. The ants “tell” the observer where they think their nest is, by looking back to it. Pirouettes are only performed by Cataglyphis ants inhabiting an environment with a prominent visual panorama. This indicates, that pirouettes are performed to learn the visual panorama. Voltes, on the other hand, might be used for calibrating the celestial compass of the ants. In my doctoral thesis, I employed a wide range of state-of-the-art techniques from different disciplines in biology to gain a deeper understanding of how navigational information is acquired, memorized, used, and calibrated during the transition phase from interior worker to outdoor forager. I could show, that celestial orientation cues that provide the main compass during foraging, do not guide the ants during the look-backbehavior of initial learning walks. Instead Cataglyphis nodus relies on the earth’s magnetic field as a compass during this early learning phase. While not guiding the ants during their first walks outside of the nest, excluding the ants from perceiving the natural polarization pattern of the skylight has significant consequences on learning-related plasticity in the ants’ brain. Only if the ants are able to perform their learning-walk behavior under a skylight polarization pattern that changes throughout the day, plastic neuronal changes in high-order integration centers are induced. Especially the mushroom bogy collar, a center for learning and memory, and the central complex, a center for orientation and motor control, showed an increase in volume after learning walks. This underlines the importance of learning walks for calibrating the celestial compass. The magnetic compass might provide the necessary stable reference system for the ants to calibrate their celestial compass and learn the position of landmark information. In the ant brain, visual information from the polarization-sensitive ocelli converge in tight apposition with neuronal afferents of the mechanosensitive Johnston’s organ in the ant’s antennae. This makes the ants’ antennae an interesting candidate for studying the sensory bases of compass calibration in Cataglyphis ants. The brain of the desert navigators is well adapted to successfully accomplish their navigational needs. Females (gynes and workers) have voluminous mushroom bodies, and the synaptic complexity to store large amount of view-based navigational information, which they acquire during initial learning walks. The male Cataglyphis brain is better suited for innate behaviors that support finding a mate. The results of my thesis show that the well adapted brain of C. nodus ants undergoes massive structural changes during leaning walks, dependent on a changing celestial polarization pattern. This underlies the essential role of learning walks in the calibration of orientation systems in desert ants. / Die Gestirne helfen nicht nur Menschen uns zurecht zu finden, sondern auch Tiere können Sonne, Mond und Sterne für Navigation nutzen. Dabei gilt es aber zu beachten, dass die Himmelskörper ihre Position abhängig von der Tageszeit, den Jahreszeiten und dem Standort auf der Erde verändern. Um anhand von Himmelseigenschaften erfolgreich navigieren zu können, ist es deshalb unerlässlich diese Himmelsrotation zu kennen und für sie zu kompensieren. Menschen haben dafür bereits in der Antike komplizierte Maschinen wie den Antikythera Mechanismus entwickelt, Tiere dagegen brauchen nur ihr Gehirn. Wüstenameisen der Galtung Cataglyphis sind kleine Meisternavigatoren. Sie benutzen einen Himmelskompass, basierend auf der Sonne und dem mit ihr assoziierten Polarisationsmuster des Himmels, und einen Schrittintegrator, um einen Vektor zu bestimmen, der immer genau zu ihrem Ausgangspunkt zurück zeigt. Dieser Orientierungsmechanismus heißt Wegintegration. Da sich allerdings die Position der Sonne am Himmel und damit auch das Polarisationsmuster des Himmels über den Tag verändern, muss Cataglyphis für diese Veränderung kompensieren. Würde sie das nicht tun, würde ihr Kompass morgens in eine ganz andere Richtung als abends zeigen. Deshalb müssen Ameisen den Sonnenverlauf erlernen bevor sie zu ihren weitläufigen Futtersuchläufen aufbrechen. Cataglyphis führt dazu ein strukturiertes Lernlaufverhalten durch während des Übergangs von Innendiensttier zu Sammlerinnen. Dabei laufen die Ameisen in kleinen Schlaufen um ihren Nesteingang und stoppen ihre Vorwärtsbewegung mehrmalig, um Drehungen durchzuführen. Diese Drehungen sind entweder kleine gelaufene Kreise (Volten) oder Drehungen um die eigene Achse (Pirouetten). Nur Cataglyphis, die Gegenden mit einem reichhaltigen visuellen Panorama bewohnen, führen Pirouetten aus bei denen sie zurück zu ihrem Nesteingang schauen. Dies legt nahe, dass während Pirouetten das Panorama gelernt wird. Während Volten wird wohl der Himmelskompass kalibriert. Die Rückdrehungen während ihrer Lernläufe geben die einmalige Möglichkeit, die Ameise zu „fragen“ wo sie denkt, dass ihr Nest sei und damit ihren Wegintegrator auszulesen. In meiner Doktorarbeit kombinierte ich viele biologischen Methoden unterschiedlicher Disziplinen um zu untersuchen wie die Ameisen ihre Navigationssysteme während der ersten Läufe außerhalb des Nestes erlernen, speichern, kalibrieren und später nutzen. Ich konnte zeigen, dass Himmelsinformationen, die bei Sammlerinnen als wichtigster 4 Kompass dienen, nicht für die Orientierung der Rückblicke während Lernläufen dienen. Stattdessen nutzten naive Cataglyphis nodus das Erdmagnetfeld als Kompass. Obwohl Himmelsinformationen nicht als Kompass während der Lernläufe genutzt werden, spielen sie eine essentielle Rolle für neuroplastische Veränderungen im Gehirn der Ameisen. Nur wenn Ameisen ihre Lernläufe unter einem Polaristaionsmuster, das sich über den Tag hinweg verändert, ausführen, kommt es zu plastischen Veränderungen in neuronalen Integrationszentren. Besonders die Pilzkörper, Zentren für Lernen und Gedächtnis, und der Zentralkomplex, Zentrum für Orientierung und Bewegungssteuerung, nehmen im Volumen nach Lernläufen zu. Lernläufe spielen also eine wichtige Rolle für die Kalibrierung der Navigationsinformationen. Das Erdmagnetfeld könnte das für die Kalibierung notwendige erdgebundene, stabile Referenzsystem bieten, an dem die Himmelsbewegung gelernt wird. Im Ameisengehirn laufen visuelle Informationen von den polarisatiossensitiven Ocelli mit Afferenzen des mechanosensitiven Johnstonschen Organ aus der Antenne zusammen. Die Antenne könnte daher eine wichtiges Organ für die Kalibrierung der Orientierungssysteme sein. Das kleine Gehirn der Ameisen ist bestens an ihre Anforderungen als große Navigatoren angepasst. Weibliche C. nodus (Arbeiterinnen und Königinnen) besitzen große Pilzkörper mit einer Anzahl an Synapsen, die es ihnen erlaubt eine Vielzahl von Umgebungsbildern zu speichern, die sie während ihrer initialen Lernläufe lernen müssen. Das männliche Cataglyphis-Gehirn ist besser auf angeborene Orientierungsstrategien angepasst, die ihm helfen einen Geschlechtspartner zu finden. Die Ergebnisse meiner Doktorarbeit zeigen, dass das an die navigatorischen Herausforderungen angepasste Gehirn von C. nodus signifikante neuronale Veränderungen in Abhängigkeit eines sich veränderten Polaristaionsmusters während der Lernläufe erfährt. Dies zeigt die essentielle Rolle der Lernläufe in der Kalibrierung der Navigationssysteme von Wüstenameisen.

The application of robotics in cluttered and dynamic environments provides a wealth of challenges. This thesis proposes a deep reinforcement learning based system that determines collision free navigation robot velocities directly from a sequence of depth images and a desired direction of travel. The system is designed such that a real robot could be placed in an unmapped, cluttered environment and be able to navigate in a desired direction with no prior knowledge. Deep Q-learning, coupled with the innovations of double Q-learning and dueling Q-networks, is applied. Two modifications of this architecture are presented to incorporate direction heading information that the reinforcement learning agent can utilize to learn how to navigate to target locations while avoiding obstacles. The performance of the these two extensions of the D3QN architecture are evaluated in simulation in simple and complex environments with a variety of common obstacles. Results show that both modifications enable the agent to successfully navigate to target locations, reaching 88% and 67% of goals in a cluttered environment, respectively.

In the case of one car following another to a destination, it is very effective at getting the second vehicle to the destination quickly; however, the driver of the second car may not learn the route. Yet, for individuals, such as firefighters, law enforcement, and military personnel, it is imperative that a route be learned quickly and accurately and that an awareness of the situation is maintained while they traverse the given route. This leads to three questions, (a) will navigation aids affect initial route navigation; (b) will navigation aids affect retention; and (c) will navigation aids affect situation awareness while en route? The hypotheses of this study were that navigation aids would significantly increase the speed at which a person can initially navigate a route, but the use of the aids would significantly decrease the retention of the route navigated. The findings of this study support the hypotheses. The results suggest that participants that followed a confederate and participants that were given verbal directions were quicker and made fewer errors than participants that reviewed a map or initially figured the route out on their own (control group). The study also showed that as the participants navigated the route for a second time with no navigational assistance, the ones that reviewed a map or that were in the control group outperformed participants that initially had a confederate to follow or were given verbal directions their first time through. Finally, no real effects were found on the participants' situation awareness during the retention portion of the study.

The hippocampus of birds and mammals has been shown to play a crucial role in spatial memory and navigation. The hippocampus exhibits plasticity in adulthood in response to diverse environmental factors associated with spatial demands placed on an animal. The cortical telencephalon of squamate reptiles has been implicated as a functional homologue to the hippocampus. This study sought to experimentally manipulate the navigational demands placed on free-ranging northern Pacific rattlesnakes (Crotalus o. oreganus) to provide direct evidence of the relationship between spatial demands and neuroplasticity in the cortical telencephalon of the squamate brain. Adult male rattlesnakes were radio-tracked for two months, during which one of three treatments was imposed weekly: 225 meter translocation in a random direction, 225 meter walk and release at that day’s capture site (handling control), and undisturbed control. Snakes were then sacrificed and brains were removed and processed for histological analysis of cortical features. The volume of the medial cortex was significantly larger in the translocated group compared to undisturbed controls. No differences in dorsal or lateral cortical volume were detected among the groups. Numbers of 5-Bromo-2’-deoxyuridine (BrdU) -labeled cells in the medial and dorsal cortices three weeks after BrdU injection were not affected by treatment. The activity range was larger in the translocated group compared to handled and undisturbed controls. A causal relationship between increased navigation in a free-ranging reptile and changes in brain morphology was established. The use of translocation as a conservation strategy for reptiles is a controversial topic revisited many times. Previous studies have demonstrated the aberrant movement patterns and mortality caused by translocation and have established that short-distance translocation within an animal’s home range is best for the animal. In conjunction with the neuroplasticity study, we examined the physiological impacts that repeated short-distance translocation and handling have on reptiles. This is essential knowledge if the efficacy of the technique is to be properly evaluated. Baseline and stressed concentrations of corticosterone and testosterone were assayed in blood taken immediately upon capture and following one hour of confinement in a bucket. Neither baseline nor stressed concentrations of either hormone were impacted by translocation or handling. Body condition and change in mass were not affected. Translocated animals had larger MCP activity ranges than handled and undisturbed animals at the 95%, but not 100% levels, while an interaction between time and treatment impacted other movement parameters.Treatment had no effect on a number of behaviors observed during visits to each animal. We suggest that rattlesnakes are quite resistant to potential impacts on their physiology and behavior enacted by frequent short-distance translocation or handling. Additionally, studies that require frequent handling of reptilian subjects are not likely to severely alter stress physiology.

The main theme of this research will be to develop solutions to the widely known 3-part question in mobile robotics comprising of "Where am I" "Where should I be" and "How do I get there". This can be achieved by implementing automation algorithms. Automation algorithms or control algorithms are vital components of any autonomous vehicle. Design and development of both prototype and full-scale control algorithms for a Long-Airdox Full Dimension Continuous Haulage system will be the main focus. Automation is a highly complex task, which aims at achieving increased levels of equipment efficiency by eliminating errors that arise due to human interference. Achieving a fully autonomous operation of a machine involves a variety of high-level interlaced functions that work in harmony, and at the same time perform functions that mimic the human operator. Automation has expanded widely in the field of mobile robotics, thus leading to the development of autonomous robots, automated guided vehicles and other autonomous vehicles. An indispensable element of an autonomous vehicle is a navigation system that steers it to a required destination. The vehicle must be able to determine its relationship to the environment by sensing, and also must be able to decide what actions are required to achieve its goal(s) in the working environment. The goal of this research is to demonstrate a fully autonomous operation of the Continuous Haulage System, and to establish its potential advantages. / Master of Science

The number of objects occupying orbital regimes beyond Geosynchronous Earth Orbit and cislunar space are expected to grow in the coming years; Especially with the Moon reemerging as latest frontier in the race for space exploration and technological superiority. In order to support this growth, new methods of autonomously navigating in cislunar space are necessary to reduce demand and reliance on ground based tracking infrastructure. Periodic orbits about the first libration point offer favorable vantage points for scientific or military spacecraft missions involving the Earth or Moon. This thesis develops a new autonomous spacecraft navigation method for cislunar space and analyzes its performance applied to Lyapunov and halo orbits around $L_1$. This method uses existing lunar ranging retroreflectors (LRRR) installed on the Moon's surface in the 1960s and 1970s. A spacecraft can make laser ranging measurements to the LRRR to estimate its orbit states. A simulation platform was created to test this concept in the circular restricted three body problem and evaluate its performance. This navigation method was found to be successful for a subset of Lyapunov and halo orbits when cycling the five measurement targets. Simulation data showed that sub-kilometer position estimation and sub 2 centimeter per second velocity accuracies are achievable without receiving any state updates from external sources. / Master of Science / The number of objects occupying the space between the Earth and Moon (cislunar space) is expected to grow in the coming years as the Moon regains popularity in the latest race for space exploration and technological superiority. In order to support this growth, new methods of determining a spacecraft's position and velocity while in this region of space are necessary to reduce demand and dependence on Earth based methods, which have historically relied upon. Repeating orbits around the equilibrium point between the Earth and Moon provide valuable observation points for scientific and military spacecraft missions. This thesis develops a new spacecraft navigation method for cislunar space and analyzes how well it performs in two different types of orbits, Lyapunov and halo orbits. This method uses existing laser reflector panels that were installed on the Moon's surface in the 1960s and 70s. A spacecraft can use these panels to make range or distance measurements in order to estimate its position and velocity. Software was written to simulate the motion of a spacecraft as it is acted on by gravity from the Earth and Moon. Different scenarios were then simulated and used to test this concept and evaluate its performance. Lunar laser ranging was found to be successful for a some Lyapunov and halo orbits when switching between the five different reflector panels on the Moon. Data generated from the simulations show that position can be estimated with errors less than SI{1}{kilo meter}, and velocity error on the order of a few centimeters per second, all without receiving any additional information from Earth based systems.

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