Biologically Plausible Spatial Navigation for a Mobile Robot

This thesis investigates the implementation of a biologically plausible navigation system on a mobile robot platform for the dual purpose of furthering robot navigation research and understanding of biological navigation systems. The aim of this work is to take steps towards bridging the broad gulf that exists between robot navigation research and biological navigation research and modelling.This dissertation reviews the extensive literature in three diverse fields of research; biological studies of animal navigation, computational modelling of animal navigation and robot navigation research. In particular, this thesis focuses on studies of rats with an emphasis on their cognitive navigation abilities. The hippocampus, which forms a large portion of the rat cerebral cortex, is believed to play a central role in the rat's spatial navigation mechanisms and forms the primary focus of this thesis.Studies on the rat hippocampus, while the animals perform free spatial navigation tasks, have begun to reveal an increasingly detailed picture of how rats represent their location within the world. In particular, it appears that rats have separate representations that encode their spatial location and orientation in a world centred context independent of reward conditions. Most results indicate that these spatial representations are formed through the integration of ideothetic movement information, called path integration, with sensory stimuli. Indeed, it seems that the animals predominantly use ideothetic mechanisms to update their spatial
representations and rely on sensory stimuli to correct for the inevitable error that accumulates.Numerous models of rat navigation, based on the observed biological results, have been proposed with varying degrees of simulation. In general, no model is complete, or comprehensive, in the sense that it addresses all the implementation issues in a systematic and realistic manner. In contrast, successful robot navigation systems, by necessity, do address all the implementation issues. This thesis represents an attempt at implementing a rat navigation model on a real robot platform with an eye for developing an autonomous system.The VIPER robot was custom built for this task and represents a semipowerful, general purpose, robot platform with monocular vision as the primary sensor. This thesis describes and validates, the navigation architecture developed for the VIPER robot. The system takes a holistic approach with the underlying guide of biological plausibility and autonomous operation. This thesis reports on the investigations into reactive navigation and high-speed reactive navigation along with
investigations into place and goal memory systems. In all cases, the investigations
focused on pragmatic biologically plausibility. That is, biological plausibility without
compromising the computational performance, or autonomy of the system. Hence, the robot operates in an autonomous manner in real-time for all the investigations
reported in this dissertation.Many of the robot investigations proved highly successful, however, due to time constraints it was not possible to achieve the full aim of the project and make the system completely autonomous. Moreover, some of the system components proved only semi-reliable. Where the navigation system is incomplete, or not totally successful, preliminary investigations of better mechanisms were carried and are
reported in this dissertation. Thus, while this thesis in itself does not bridge the gap
between biology and robotics it represents a significant step towards that direction.