The use of atom probe tomography (APT) [1] to investigate the microstructure of insulating oxide materials has been of interest for many years [2]. Recently, both voltage-pulsed and laser-pulsed methods has been used to analyze thin films (~1-2nm) of various oxides [3][4][5] and thicker metal oxide films up to ~20nm created directly on metal needles [6]. This paper expands this later category of "bulk"-like oxide films through the application of laser-pulsed atom probe to samples containing large regions of SiO 2 or Al 2 O 3 . Silicon dioxide is ubiquitous in the semiconductor industry, being implemented, for example, as a gate oxide, as an electrically insulating backfill material and as a silicon-on-insulator substrate material. An example mass spectrum from a backfill region of silicon dioxide 30x70x10nm (part of a larger total volume of material ~10x that size) is shown in Fig. 1. The mass peaks are all identifiable, including SiO in 1+ and 2+ charge states and SiO 2 . If hydrogen is ranged in a concentration calculation it accounts for 4.7%, however it is likely that as least some of it is being picked up from the vacuum and thus we have calculated a concentration of 37.0±0.16%Si -63.0±0.16%O (excluding hydrogen), which is slightly oxygen deficient.Alumina, both pure and in composite forms, has a variety of uses due to its high temperature performance, wear and corrosion resistance, hardness, and dielectric properties. We have investigated the feasibility of laser-pulsed APT on bulk alumina commonly used as a substrate for III-V (particularly GaN) semiconductor deposition. Fig. 2 shows the mass spectrum obtained from an analyzed volume of 80x80x40nm. Although the spectrum contains many complex molecular ions, all of the peaks, excluding hydrogen, are identifiable in terms of combinations of Al and O in various ratios and charge states. A concentration (excluding hydrogen, which accounted for 3.6%) was calculated from the spectrum as 37.8±0.03%Al -62.2.0±0.03%O. A second alumina mass spectrum from a volume of 50x50x50nm is shown in Fig.3. This analysis is of an oxidized NiAl diffusion coating [7]. The concentration (excluding hydrogen, which accounted for 0.74%) was calculated to be 37.4±0.03%Al -62.6.0±0.03%O, again slightly oxygen enriched, similar to the data from Fig. 2, but quite close to stoichiometric alumina. All concentrations were calculated from the spectra by peak ranging at one-tenth of the maximum value or, if this was not possible, by using a visual estimate of the noise level, Fig. 4. Simple background subtraction was performed on the spectra in Fig. 2 using a pre-peak range of the same number of bins as the peak range (Fig. 4), with the result being a concentration of 37.2±0.04%Al -62.8.0±0.04%O.
If robots are to cooperate with humans in an increasingly human-like manner, then significant progress must be made in their abilities to observe and learn to perform novel goal directed actions in a flexible and adaptive manner. The current research addresses this challenge. In CHRIS.I [1], we developed a platform-independent perceptual system that learns from observation to recognize human actions in a way which abstracted from the specifics of the robotic platform, learning actions including "put X on Y" and "take X". In the current research, we extend this system from action perception to execution, consistent with current developmental research in human understanding of goal directed action and teleological reasoning. We demonstrate the platform independence with experiments on three different robots. In Experiments 1 and 2 we complete our previous study of perception of actions "put" and "take" demonstrating how the system learns to execute these same actions, along with new related actions "cover" and "uncover" based on the composition of action primitives "grasp X" and "release X at Y". Significantly, these compositional action execution specifications learned on one iCub robot are then executed on another, based on the abstraction layer of motor primitives. Experiment 3 further validates the platformindependence of the system, as a new action that is learned on the iCub in Lyon is then executed on the Jido robot in Toulouse. In Experiment 4 we extended the definition of action perception to include the notion of agency, again inspired by developmental studies of agency attribution, exploiting the Kinect motion capture system for tracking human motion. Finally in Experiment 5 we demonstrate how the combined representation of action in terms of perception and execution provides the basis for imitation. This provides the basis for an open ended cooperation capability where new actions can be learned and integrated into shared plans for cooperation. Part of the novelty of this research is the robots' use of spoken language understanding and visual perception to generate action representations in a platform independent manner basedManuscript received March 15, 2011. This work was fully supported by European FP7 ICT project CHRIS).
Abstract-In this work, we present a Hidden Markov Model (HMM) based workflow analysis of an assembly task jointly performed by a human and an assistive robotic system. In an experiment subjects had to assemble a tower by combining six cubes with several bolts for their own without the influence of a robot or any other technical device. To estimate the current action of the human, we have trained composite HMMs. After the successful evaluation on disjunct experimental data sets, the models are transferred to the assistive robotic system JAHIR, where the same assembly tasks was executed. A new 3D occupancy grid approach was used to determine the hand positions of the worker. The positions were then used to compute the inputs of the analysis HMMs. The workflow of the right hand could be recognized with an accuracy of 92.26 % which is nearly as good as the recognition rate of reference experiments.
Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008
Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006
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