Time-Lapse Monitoring of Two-Dimensional Non-Uniform Unsaturated Flow Processes Using Ground Penetrating Radar

Unsaturated flow in the vadose zone often manifests as preferential flow resulting in transport of water and solutes through the soil much faster than would occur for uniform matrix flow. Time-lapse ground penetrating radar (TLGPR) shows promise as a non-invasive means to monitor unsaturated flow and here is used to monitor lab-scale forced infiltration events for capturing evidence of non-uniform and preferential flow phenomena directly from arrivals in the GPR images while simultaneously characterizing parameters of the flow system, such as bulk water content and rates of wetting front movement. This was accomplished by 1) directly interpreting transient arrivals in GPR profiles for evidence of ono-uniform flow and 2) with the aid of migration processing techniques to improve the quality of GPR images for identification and tracking of transient arrivals related to wetting in the soil. A novel method is described and evaluated to characterize the 2D velocity structure of a soil and used to migrate the GPR images. This method incorporates multi-offset measurements to characterize the depth to a potentially unknown static reflector and root mean square (RMS) velocity above the reflector with incremental changes in travel time to the static reflector and a transient reflector (i.e. the wetting front) determined from single-offset constant offset profiles to determine incremental changes in velocity above and below the transient arrival. The method is applied to TLGPR data during infiltration experiments in a 60 cm deep sand-filled tank and monitored with water content probes. To verify the approach the methodology is applied to GPR data simulated using transient water contents generated by the unsaturated flow simulator HYDRUS 2D given lab-measured hydraulic properties of the soil. For both the empirical and simulated data, we found that the 2D velocity analysis was effective in monitoring changes in the wetting front and that migration of the reflection profiles was able to improve the interpretation of non-uniform flow

Visuo-Haptic Grasping of Unknown Objects through Exploration and Learning on Humanoid Robots

Die vorliegende Arbeit befasst sich mit dem Greifen unbekannter Objekte durch humanoide Roboter. Dazu werden visuelle Informationen mit haptischer Exploration kombiniert, um Greifhypothesen zu erzeugen. Basierend auf simulierten Trainingsdaten wird außerdem eine Greifmetrik gelernt, welche die Erfolgswahrscheinlichkeit der Greifhypothesen bewertet und die mit der größten geschätzten Erfolgswahrscheinlichkeit auswählt. Diese wird verwendet, um Objekte mit Hilfe einer reaktiven Kontrollstrategie zu greifen. Die zwei Kernbeiträge der Arbeit sind zum einen die haptische Exploration von unbekannten Objekten und zum anderen das Greifen von unbekannten Objekten mit Hilfe einer neuartigen datengetriebenen Greifmetrik

Autonomous Mechanical Assembly on the Space Shuttle: An Overview

The space shuttle will be equipped with a pair of 50 ft. manipulators used to handle payloads and to perform mechanical assembly operations. Although current plans call for these manipulators to be operated by a human teleoperator. The possibility of using results from robotics and machine intelligence to automate this shuttle assembly system was investigated. The major components of an autonomous mechanical assembly system are examined, along with the technology base upon which they depend. The state of the art in advanced automation is also assessed