Virtual Borders: Accurate Definition of a Mobile Robot's Workspace Using Augmented Reality

We address the problem of interactively controlling the workspace of a mobile robot to ensure a human-aware navigation. This is especially of relevance for non-expert users living in human-robot shared spaces, e.g. home environments, since they want to keep the control of their mobile robots, such as vacuum cleaning or companion robots. Therefore, we introduce virtual borders that are respected by a robot while performing its tasks. For this purpose, we employ a RGB-D Google Tango tablet as human-robot interface in combination with an augmented reality application to flexibly define virtual borders. We evaluated our system with 15 non-expert users concerning accuracy, teaching time and correctness and compared the results with other baseline methods based on visual markers and a laser pointer. The experimental results show that our method features an equally high accuracy while reducing the teaching time significantly compared to the baseline methods. This holds for different border lengths, shapes and variations in the teaching process. Finally, we demonstrated the correctness of the approach, i.e. the mobile robot changes its navigational behavior according to the user-defined virtual borders.Comment: Accepted on 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), supplementary video: https://youtu.be/oQO8sQ0JBR

This Far, No Further: Introducing Virtual Borders to Mobile Robots Using a Laser Pointer

We address the problem of controlling the workspace of a 3-DoF mobile robot. In a human-robot shared space, robots should navigate in a human-acceptable way according to the users' demands. For this purpose, we employ virtual borders, that are non-physical borders, to allow a user the restriction of the robot's workspace. To this end, we propose an interaction method based on a laser pointer to intuitively define virtual borders. This interaction method uses a previously developed framework based on robot guidance to change the robot's navigational behavior. Furthermore, we extend this framework to increase the flexibility by considering different types of virtual borders, i.e. polygons and curves separating an area. We evaluated our method with 15 non-expert users concerning correctness, accuracy and teaching time. The experimental results revealed a high accuracy and linear teaching time with respect to the border length while correctly incorporating the borders into the robot's navigational map. Finally, our user study showed that non-expert users can employ our interaction method.Comment: Accepted at 2019 Third IEEE International Conference on Robotic Computing (IRC), supplementary video: https://youtu.be/lKsGp8xtyI

A Framework for Interactive Teaching of Virtual Borders to Mobile Robots

The increasing number of robots in home environments leads to an emerging coexistence between humans and robots. Robots undertake common tasks and support the residents in their everyday life. People appreciate the presence of robots in their environment as long as they keep the control over them. One important aspect is the control of a robot's workspace. Therefore, we introduce virtual borders to precisely and flexibly define the workspace of mobile robots. First, we propose a novel framework that allows a person to interactively restrict a mobile robot's workspace. To show the validity of this framework, a concrete implementation based on visual markers is implemented. Afterwards, the mobile robot is capable of performing its tasks while respecting the new virtual borders. The approach is accurate, flexible and less time consuming than explicit robot programming. Hence, even non-experts are able to teach virtual borders to their robots which is especially interesting in domains like vacuuming or service robots in home environments.Comment: 7 pages, 6 figure

Irradiated atmospheres of accreting magnetic white dwarfs with an application to the polar AM Herculis

We present a pilot study of atmospheres of accreting magnetic white dwarfs irradiated by intense fluxes at ultraviolet to infrared wavelengths. The model uses a standard LTE stellar atmosphere code which is expanded by introducing an angle-dependent external radiation source. The present results are obtained for an external source with the spectral shape of a 10 000 K blackbody and a freely adjustable spectral flux. The model provides an explanation for the observed largely filled-up Lyman lines in the prototype polar AM Herculis during its high states. It also confirms the hypotheses (i) that irradiation by cyclotron radiation and other radiation sources is the principle cause for the large heated polar caps surrounding the accretion spots on white dwarfs in polars and (ii) that much of the reprocessed light appears in the far ultraviolet and not in the soft X-ray regime as suggested in the original simple theories. We also briefly discuss the role played by hard X-rays in heating the polar cap

Le Brachypode rupestre (Brachypodium rupestre) en Hesse

Aus Hessen war Brachypodium rupestre bisher nur von einem Fundort veröffentlicht. Durch gezielte Suche und einen Zufallsfund kamen in den letzten Jahren fünf weitere hinzu. Die Wuchsorte sind anthropogene Böschungen von Straßen und Hochwasserrückhaltebecken, nur in einem Fall wachsen die Pflanzen auf einem naturnahen Standort in einer extensiv bewirtschafteten Stromtalwiese. Die Vorkommen gehen wahrscheinlich alle auf Ansaat zurück, entweder auf direkte Ansaat am Wuchsort oder ausgehend von den Primärpopulationen auf Verdriftung der Diasporen mit Hochwässern. Die Art ist in Hessen als eingebürgerter Neophyt einzustufen.Until recently, Brachypodium rupestre was recorded as occurring in Hesse in only a single location. Recent field work and a chance finding have revealed a further five locations where this species occurs. These sites are located on anthropogenic embankments of roads and floodwater retention basins, apart from at one site where the plants grow under semi-natural conditions in an extensively cultivated riparian meadow. All populations probably became established as a result of sowing, either directly or as a result of diaspore drift from primary populations during flooding. In Hesse, B. rupestre has the status of an established neophyte.Le Brachypodium rupestre n’était connu en Hesse dans les publications que dans une seule station. Par des recherches ciblées et par une trouvaille fortuite cinq autres s’y sont ajoutées ces dernières années. Les habitats sont des talus anthropogènes le long des routes et en bordure de bassins de retenue des eaux de crue ; une exception cependant: des spécimens poussent sur un terrain semi-naturel dans une prairie de fauche extensive. Les populations proviennent sans doute d’ensemencement, soit directement sur la station soit en artant de la population primaire par les diaspores à la dérive lors des crues. L’espèce est à classer en Hesse comme néophyte établi

Zur Differenz zwischen Religion und Religiosität bei jungen Menschen. Ein Problemaufriss

Streib H. Zur Differenz zwischen Religion und Religiosität bei jungen Menschen. Ein Problemaufriss. In: Meier U, Kropac U, König K, eds. Zwischen Religion und Religiosität. Regensburg: Pustet; 2015: 27-40

Didaktische Konzeptionen und wissenschaftliche Leitbilder in deutschen und französischen Erdkundeschulbüchern – untersucht anhand der Häufigkeit eindeutig definierbarer Darstellungs- und Auftragsformen

Die Ziele, wissenschaftlichen Leitbilder und didaktischen Konzeptionen des Geographieunterrichts werden in Deutschland in den Richtlinien der Bundesländer, in Frankreich in den sogenannten programmes vorgegeben. In dieser Untersuchung sollen jeweils sechs französische und deutsche Erdkunde-Schulbücher, die ausnahmslos in den Jahren zwischen 1992-1998 erschienen sind, bezüglich der Umsetzung dieser Ziele, Leitbilder und Konzeptionen vergleichend anhand der Häufigkeit eindeutig definierbarer Darstellungs- und Auftragsformen sowie Fragestellungen analysiert werden

N-Ethoxycarbonylazepine

By irradiating a solution of ethyl azidocarbonate in benzene with ultraviolet light, we obtained N-ethoxycarbonylazepine (2) in ca. 70 % yield as a stable yellow oil, b.p. 130°C/20 mm (λmax = 208 mμ (log ε= 4.44) and λmax = 330 mμ(log ε = 2.72) in n-hexane)