Efficient and intuitive teaching of redundant robots in task and configuration space

Emmerich C. Efficient and intuitive teaching of redundant robots in task and configuration space. Bielefeld: Universität Bielefeld; 2016.A major goal of current robotics research is to enable robots to become co-workers that learn from and collaborate with humans efficiently. This is of particular interest for small and medium-sized enterprises where small batch sizes and frequent changes in production needs demand a high flexibility in the manufacturing processes. A commonly adopted approach to accomplish this goal is the utilization of recently developed lightweight, compliant and kinematically redundant robot platforms in combination with state-of-the-art human-robot interfaces. However, the increased complexity of these robots is not well reflected in most interfaces as the work at hand points out. Plain kinesthetic teaching, a typical attempt to enable lay users programming a robot by physically guiding it through a motion demonstration, not only imposes high cognitive load on the tutor, particularly in the presence of strong environmental constraints. It also neglects the possible reuse of (task-independent) constraints on the redundancy resolution as these have to be demonstrated repeatedly or are modeled explicitly reducing the efficiency of these methods when targeted at non-expert users. In contrast, this thesis promotes a different view investigating human-robot interaction schemes not only from the learner’s but also from the tutor’s perspective. A two-staged interaction structure is proposed that enables lay users to transfer their implicit knowledge about task and environmental constraints incrementally and independently of each other to the robot, and to reuse this knowledge by means of assisted programming controllers. In addition, a path planning approach is derived by properly exploiting the knowledge transfer enabling autonomous navigation in a possibly confined workspace without any cameras or other external sensors. All derived concept are implemented and evaluated thoroughly on a system prototype utilizing the 7-DoF KUKA Lightweight Robot IV. Results of a large user study conducted in the context of this thesis attest the staged interaction to reduce the complexity of teaching redundant robots and show that teaching redundancy resolutions is feasible also for non-expert users. Utilizing properly tailored machine learning algorithms the proposed approach is completely data-driven. Hence, despite a required forward kinematic mapping of the manipulator the entire approach is model-free allowing to implement the derived concepts on a variety of currently available robot platforms

Synthesis and electrical characterization of intrinsic and in situ doped Si nanowires using a novel precursor

Perchlorinated polysilanes were synthesized by polymerization of tetrachlorosilane under cold plasma conditions with hydrogen as a reducing agent. Subsequent selective cleavage of the resulting polymer yielded oligochlorosilanes SinCl2n+2 (n = 2, 3) from which the octachlorotrisilane (n = 3, Cl8Si3, OCTS) was used as a novel precursor for the synthesis of single-crystalline Si nanowires (NW) by the well-established vapor–liquid–solid (VLS) mechanism. By adding doping agents, specifically BBr3 and PCl3, we achieved highly p- and n-type doped Si-NWs by means of atmospheric-pressure chemical vapor deposition (APCVD). These as grown NWs were investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as electrical measurements of the NWs integrated in four-terminal and back-gated MOSFET modules. The intrinsic NWs appeared to be highly crystalline, with a preferred growth direction of [111] and a specific resistivity of ρ = 6 kΩ·cm. The doped NWs appeared to be [112] oriented with a specific resistivity of ρ = 198 mΩ·cm for p-type Si-NWs and ρ = 2.7 mΩ·cm for n-doped Si-NWs, revealing excellent dopant activation

Verhandlungsdemokratische Willensbildung und korporatistische Entscheidungsfindung am Ende? Einschneidende Veränderungen am Beispiel der Gestaltung des österreichischen Arbeitsrechtes

'Als Resultat der Zusammenarbeit, Konzertierung und Akkordierung zwischen den jeweiligen Regierungen und den großen Dachverbänden der ArbeitgeberInnen und ArbeitnehmerInnen in Politikfeldern wie der Sozialpolitik (näherhin dem Arbeitsrecht) weisen die politischen Entscheidungsfindungsprozesse in Österreich über einen langen Zeitraum eine beträchtliche Kontinuität auf. Dies ist einer der Gründe dafür, dass Österreich in der einschlägigen sozialwissenschaftlichen Literatur als Repräsentant (neo)korporatistischer Interessenpolitik und der Verhandlungsdemokratie gilt. Unter Verwendung des von Tálos/Kittel modifizierten Ansatzes des akteurzentrierten Institutionalismus untersucht der vorliegende Beitrag am Themenbereich des Arbeitsrechtes, ob seit dem Antritt der bürgerlich-konservativen Regierungskoalition von ÖVP und FPÖ im Jahr 2000 Veränderungen des traditionellen Musters der politischen Willensbildung und Entscheidungsfindung eingetreten sind. Das Ergebnis der Analyse lautet, dass Österreichs Politik - ungeachtet formal-institutioneller Kontinuitäten - de facto den Wandel von einer korporatistischen Konkordanz- bzw. Verhandlungsdemokratie zu einer Konfliktdemokratie bereits vollzogen hat.' (Autorenreferat)'In Austrian politics for a long period a specific type of cooperation, concertation and arrangement has been characteristic for the relations between government and interest associations of employers and employees in policy areas as e.g. social policy (and particularly in labour law). That's why respective literature has classified Austria as a typical model of neocorporatist interest intermediation or policy concertation. Using the approach of actor-centred institutionalism modified by Tálos/Kittel, the article - analysing the example of labour legislation - aims at examining if there took place a substantial change in procedures of policy making since the conservative coalition between ÖVP and FPÖ has been taking office in spring 2000. The authors conclude that Austria's politics - irrespective of formal institutional continuity - de facto have already changed from a corporatist consensus or bargaining democracy to a democracy dominated by conflict and the principle of majority rule.' (author's abstract

Entropy production in phase field theories

Allen-Cahn (Ginzburg-Landau) dynamics for scalar fields with heat conduction is treated in rigid bodies using a non-equilibrium thermodynamic framework with weakly nonlocal internal variables. The entropy production and entropy flux is calculated with the classical method of irreversible thermodynamics by separating full divergences.Comment: 5 pages, no figure

Metronome: adaptive and precise intermittent packet retrieval in DPDK

DPDK (Data Plane Development Kit) is arguably today's most employed framework for software packet processing. Its impressive performance however comes at the cost of precious CPU resources, dedicated to continuously poll the NICs. To face this issue, this paper presents Metronome, an approach devised to replace the continuous DPDK polling with a sleep&wake intermittent mode. Metronome revolves around two main innovations. First, we design a microseconds time-scale sleep function, named hr_sleep(), which outperforms Linux' nanosleep() of more than one order of magnitude in terms of precision when running threads with common time-sharing priorities. Then, we design, model, and assess an efficient multi-thread operation which guarantees service continuity and improved robustness against preemptive thread executions, like in common CPU-sharing scenarios, meanwhile providing controlled latency and high polling efficiency by dynamically adapting to the measured traffic load

Chikungunya Fever in Travelers Returning to Europe from the Indian Ocean Region, 2006

Chikungunya fever should be added to the list of differential diagnoses for ill travelers returning from this region

Genetics of venous thrombosis: insights from a new genome wide association study

Background: Venous Thrombosis (VT) is a common multifactorial disease associated with a major public health burden. Genetics factors are known to contribute to the susceptibility of the disease but how many genes are involved and their contribution to VT risk still remain obscure. We aimed to identify genetic variants associated with VT risk. Methodology/Principal Findings: We conducted a genome-wide association study (GWAS) based on 551,141 SNPs genotyped in 1,542 cases and 1,110 controls. Twelve SNPs reached the genome-wide significance level of 2.0×10−8 and encompassed four known VT-associated loci, ABO, F5, F11 and FGG. By means of haplotype analyses, we also provided novel arguments in favor of a role of HIVEP1, PROCR and STAB2, three loci recently hypothesized to participate in the susceptibility to VT. However, no novel VT-associated loci came out of our GWAS. Using a recently proposed statistical methodology, we also showed that common variants could explain about 35% of the genetic variance underlying VT susceptibility among which 3% could be attributable to the main identified VT loci. This analysis additionally suggested that the common variants left to be identified are not uniformly distributed across the genome and that chromosome 20, itself, could contribute to ∼7% of the total genetic variance. Conclusions/Significance: This study might also provide a valuable source of information to expand our understanding of biological mechanisms regulating quantitative biomarkers for VT

Modeling the material resistance of wood—part 2:Validation and optimization of the meyer-veltrup model

Service life planning with timber requires reliable models for quantifying the effects of exposure-related parameters and the material-inherent resistance of wood against biotic agents. The Meyer-Veltrup model was the first attempt to account for inherent protective properties and the wetting ability of wood to quantify resistance of wood in a quantitative manner. Based on test data on brown, white, and soft rot as well as moisture dynamics, the decay rates of different untreated wood species were predicted relative to the reference species of Norway spruce (Picea abies). The present study aimed to validate and optimize the resistance model for a wider range of wood species including very durable species, thermally and chemically modified wood, and preservative treated wood. The general model structure was shown to also be suitable for highly durable materials, but previously defined maximum thresholds had to be adjusted (i.e., maximum values of factors accounting for wetting ability and inherent protective properties) to 18 instead of 5 compared to Norway spruce. As expected, both the enlarged span in durability and the use of numerous and partly very divergent data sources (i.e., test methods, test locations, and types of data presentation) led to a decrease in the predictive power of the model compared to the original. In addition to the need to enlarge the database quantity and improve its quality, in particular for treated wood, it might be advantageous to use separate models for untreated and treated wood as long as the effect of additional impact variables (e.g., treatment quality) can be accounted for. Nevertheless, the adapted Meyer-Veltrup model will serve as an instrument to quantify material resistance for a wide range of wood-based materials as an input for comprehensive service life prediction software