Zugl.: Karlsruhe, Universiẗat, Diss., 2007.

In daily life, both animals and humans are often faced with the task of returning to previously visited locations. In many cases, an organism must be able to (1) establish a directional frame of reference and (2) determine location based on surrounding cues in order to solve this problem. Moreover, successful navigation is generally thought to rely on how an organism learns and uses the metric relationships between various locations in its environment. This thesis examines various factors that affect the way animals encode and use metric information in their environment, both to orient and to navigate. A transformation approach is used to determine what aspects of metric information are learned and/or preferred. Additionally, this thesis follows a comparative approach in order to examine similarities and differences among species. In chapter 2, I show that two closely related species of chickadees differently use geometric and featural information when establishing a directional frame of reference. I suggest that ecological factors, but not rearing condition, affect the way that chickadees preferentially use metric or featural information to orient. In chapter 3, I used a similar paradigm to show that a pre-existing directional frame of reference can interact with rats’ use of metric cues to navigate. More specifically, chapter 3 shows that experience gained through training procedures affects the way that rats use metric information in a navigation task. Chapter 4 expands upon this idea, and shows that pigeons encode directional metric differently based on their past experience. Finally, in chapter 5, I examined the flexibility of use of metrics by comparing how search strategies of human adults and children can change based on a goal’s proximity to an edge. To summarize, this thesis shows that use of metric information is malleable and situation-specific and can be affected by a variety of factors including ecology, past experience and boundary information.

A subsumption-based mobile robot is extended to perform cognitive tasks. Following directions, the robot navigates directly to previously unexplored goals. This robot exploits a novel architecture based on the idea that cognition uses the underlying machinery of interaction, imagining sensations and actions.

In this thesis, we investigate the problem of path formation and prey retrieval in a swarm of robots. We present two swarm intelligence control mechanisms used for distributed robot path formation. In the first, the robots form linear chains. We study three variants of robot chains, which vary in the degree of motion allowed to the chain structure. The second mechanism is called vectorfield. In this case, the robots form a pattern that globally indicates the direction towards a goal or home location. Both algorithms were designed following the swarm robotics control principles: simplicity of control, locality of sensing and communication, homogeneity and distributedness. We test each controller on a task that consists in forming a path between two objects—the prey and the nest—and to retrieve the prey to the nest. The difficulty of the task is given by four constraints. First, the prey requires concurrent, physical handling by multiple robots to be moved. Second, each robot’s perceptual range is small when compared to the distance between the nest and the prey; moreover, perception is unreliable. Third, no robot has any explicit knowledge about the environment beyond its perceptual range. Fourth, communication among robots is unreliable and limited to a small set of simple signals that are locally broadcast. In simulation experiments we test our controllers under a wide range of conditions, changing the distance between nest and prey, varying the number of robots used, and introducing different obstacle configurations in the environment. Furthermore, we tested the controllers for robustness by adding noise to the different sensors, and for fault tolerance by completely removing a sensor or actuator. We validate the chain controller in experiments with up to twelve physical robots. We believe that these experiments are among the most sophisticated examples of self-organisation in robotics to date.

Everyday experience suggests that certain people can find their way to a destination easily, while others have considerable difficulty. This dissertation focused on gaining a greater understanding of navigational strategies that can facilitate or hinder an individual’s wayfinding performance. The first study was conducted to gain a broad idea of various factors that may influence navigational performance. Participants were guided through a building and then asked to find their way to a destination. It was found that good navigators made fewer errors in traversing a learned route than did poor navigators. They were also better at recognizing landmarks they had seen along the route, recalling the appropriate directions to be turned at each landmark, and at drawing the correct pathways on a map drawing task. A discriminant analysis revealed that the best predictor of determining navigational performance was the ability to form spatial relationships between landmarks. Results from the first study demonstrated that good navigators were better at determining spatial relationships between landmarks, but it did not address whether this was due to spatial relationships between distances and/or angles. The focus of the second study was to gain a greater understanding of the degree to which distance and angular information are used by good and poor navigators in determining spatial relationships between landmarks. Results showed that neither a distance nor an angular strategy were preferred in either group of wayfinders. An analysis of navigators initial heading angle error to a target location suggested that good wayfinders may be more efficient at finding their way because they appear to plan routes prior to initiating self-locomotion. Such pre-planning was confirmed by the fact that good wayfinders’ initial heading direction error was significantly less than in poor wayfinders. Poor wayfinders appear to head in a random direction and then attempt to determine target locations. The use of landmark information may be useful in certain contexts, but this may not always be the most efficient strategy. The last experiment was aimed at determining whether good navigators adjust strategies used (landmark vs. street), depending on contextual factors. Differences in strategies used were not found, however the results suggest that good navigators appear to be more skilled at navigating in environments rich with streets compared to poor wayfinders. Good and poor navigators were equally skilled at navigating in environments rich in landmarks. It appears that the ability to determine spatial relationships between landmarks is the strongest predictor of navigational performance compared to a wide range of other navigational skills.

Navigation är ett centralt begrepp i spelanvändning, trots att det ofta ses som ett nödvändigt ont. Det här arbetet intresserar sig för upplevelsen av navigation i två typer av programvara – spel och nyttoprogram. Detta arbete går ut på att granska hur upplevelsen av navigation i programvara är beroende på användarnas förväntningar – om användarna tror sig använda programvara för nytta eller för nöje. Arbetet använder sig av två programvaror för att undersöka detta – ett spel och ett nyttoprogram, där vardera presenteras både som spel och nyttoprogram för olika testanvändare. Genom att presentera spelet som spel för en testgrupp och nyttoprogram för en testgrupp och med dessa förutsättningar utföra användartestning av programvaran – granskar arbetet skillnaderna i hur testanvändarna upplever spelet beroende på om användarna förväntar sig att sitta vid ett spel eller sitta vid en nyttoprogramvara. På samma sätt undersöks nyttoprogrammet. Genom detta granskar arbetet hur en användare som tror sig utnyttja ett nyttoprogram som egentligen är utformat som ett spel, påverkas av inslag av speldesign. På samma sätt granskar arbetet hur en användare som tror sig sitta vid ett spel som egentligen är utformat som ett nyttoprogram, påverkas av sådana inslag. Arbetet applicerar flow för att definiera en typ av upplevelse som är positiv både i nyttoprogram och spel. Arbetet intresserar sig inte för flow som sådan utan upplevelser som bidrar till den.  GameFlow-modellen är en lista av kriterier som kan upplevas genom användning av programvara och bidrar till flowupplevelsen. Arbetet använder sig av modellen för att kunna utvärdera användarnas upplevelse av navigation i spel och nyttoprogram.

The purpose of this study is to examine which aspects of blogs and blog design that are important to blog readers but also to find new ideas for blog design. From a qualitative standpoint we have examined how seven users experience that blogs design, structure and functionalities affects the general experience of the blog. The study also examines how the users wish to interact with a blog. During two design workshops we let seven active blog readers imagine and sketch out the design and functionalities they would like in a blog. We put this in relation to theories about the anatomy of blogs, methods of design, social navigation and virtual communities. The major finding is that the aspects most important to blog readers are navigation, structure and social interaction. Based on these aspects we discuss more closely the ideas our subjects had about what the blog of their dreams would look like.

The need addressed in this thesis is to provide an Autonomous Ground Vehicle (AGV) with accurate information regarding its position, velocity, and orientation. The system chosen to meet these needs incorporates (1) a differential Global Positioning System, (2) an Inertial Measurement Unit consisting of accelerometers and angular-rate sensors, and (3) a Kalman Filter (KF) to fuse the sensor data. The obstacle avoidance software requires position and orientation to build a global map of obstacles based on the returns of a scanning laser rangefinder. The path control software requires position and velocity. The development of the KF is the major contribution of this thesis. This technology can either be purchased or developed, and, for educational and financial reasons, it was decided to develop instead of purchasing the KF software. This thesis analyzes three different cases of navigation: one-dimensional, two dimensional and three-dimensional (general). Each becomes more complex, and separating them allows a three step progression to reach the general motion solution. Three tests were conducted at the Texas A&M University Riverside campus that demonstrated the accuracy of the solution. Starting from a designated origin, the AGV traveled along the runway and then returned to the same origin within 11 cm along the North axis, 19 cm along the East axis and 8 cm along the Down axis. Also, the vehicle traveled along runway 35R which runs North-South within 0.1°, with the yaw solution consistently within 1° of North or South. The final test was mapping a box onto the origin of the global map, which requires accurate linear and angular position estimates and a correct mapping transformation.

<p>Navigation är ett centralt begrepp i spelanvändning, trots att det ofta ses som ett nödvändigt ont. Det här arbetet intresserar sig för upplevelsen av navigation i två typer av programvara – spel och nyttoprogram. Detta arbete går ut på att granska hur upplevelsen av navigation i programvara är beroende på användarnas förväntningar – om användarna tror sig använda programvara för nytta eller för nöje. Arbetet använder sig av två programvaror för att undersöka detta – ett spel och ett nyttoprogram, där vardera presenteras både som spel och nyttoprogram för olika testanvändare. Genom att presentera spelet som spel för en testgrupp och nyttoprogram för en testgrupp och med dessa förutsättningar utföra användartestning av programvaran – granskar arbetet skillnaderna i hur testanvändarna upplever spelet beroende på om användarna förväntar sig att sitta vid ett spel eller sitta vid en nyttoprogramvara. På samma sätt undersöks nyttoprogrammet. Genom detta granskar arbetet hur en användare som tror sig utnyttja ett nyttoprogram som egentligen är utformat som ett spel, påverkas av inslag av speldesign. På samma sätt granskar arbetet hur en användare som tror sig sitta vid ett spel som egentligen är utformat som ett nyttoprogram, påverkas av sådana inslag.</p><p>Arbetet applicerar flow för att definiera en typ av upplevelse som är positiv både i nyttoprogram och spel. Arbetet intresserar sig inte för flow som sådan utan upplevelser som bidrar till den.  GameFlow-modellen är en lista av kriterier som kan upplevas genom användning av programvara och bidrar till flowupplevelsen. Arbetet använder sig av modellen för att kunna utvärdera användarnas upplevelse av navigation i spel och nyttoprogram.</p>

Diss. Linköping : Univ., 2004. / Sammanfattning på engelska med titeln: The risk filled community : handling safety on a passenger ship.