Towards Inertial Sensor-Based Position Estimation in Bouldering

For some years, inertial sensors have become increasingly popular in various sports applications due to their small size and weight. However – due to the problem of sensor drift – additional sensors are usually required to obtain reliable position estimates. In this paper, we present an approach for position estimation in bouldering that relies solely on inertial sensors and domain knowledge that is modeled as a virtual sensor.Seit einigen Jahren erfreuen sich Inertialsensoren aufgrund ihrer geringen Größe und ihres geringen Gewichts zunehmender Beliebtheit in verschiedenen Sportanwendungen. Aufgrund des Problems des Sensordrifts sind jedoch in der Regel zusätzliche Sensoren erforderlich, um zuverlässige Positionsschätzungen zu erhalten. In diesem Beitrag stellen wir einen Ansatz zur Positionsschätzung beim Bouldern vor, der sich ausschließlich auf Inertialsensoren und Domänenwissen stützt, welches als virtueller Sensor modelliert wird

ECMR’13 Special Issue

This special issue contains extended versions of the best papers from the 6th European Conference on Mobile Robots (ECMR). ECMR is a biennial European forum, internationally open, that allows roboticists throughout Europe to become acquainted with the latest research accomplishments and innovations in mobile robotics and mobile human–robot systems. ECMR covers most aspects of mobile robotics research and machine intelligence, including (but not limited to) the following topics: multi-sensor fusion, localization, map building, navigation, active perception, behavior-based robotics, path and task planning, learning and adaptation, robot vision, human–robot interaction, cognitive robotics, experimental evaluation and benchmarking, 3D sensing, and applications of mobile robotics in land, water, air, underground, and space.Peer ReviewedPostprint (author's final draft

Design and On-Orbit Experience of Reaction Wheels for Small Satellites

The history of reaction wheel development at the Technische Universität Berlin (TUB) begins early in the 90s. Since then many of these reaction wheels performed on-orbit without a single failure as a part of six micro- and nanosatellite missions. The last one is the S band Network for co-operating Satellites (S-Net). S-Net is a cluster of four nanosats successfully launched in February 2018. Since then a number of communication experiments using intersatellite links have been performed by the S-Net satellites. This paper is focusing on the design and on the on orbit performance of the reaction wheels for S-Net nanosatellites. The design is based on COTS and differs considerably from the state-of-the-art one. The wheel is pressurized, allowing higher rotation speeds due to a better thermal performance as well as the use of commercial motors without any changes in ball bearings and their lubrication. Due to a better ball bearing friction the performance and, consequently, the failure tolerance have increased significantly. The wheels can run at higher speeds continuously allowing their use within momentum bias platforms. A novel suspension system helped to optimize the misalignment of the rotational axis compared to a simple spiral spring based suspension used for TUB wheels earlier. A further outstanding feature is the implementation of some additional control loops alongside with the standard current, speed and torque control. The use of built-in internal angular velocity sensors makes satellite velocity and satellite angle control modes possible. For some operational scenarios, especially for such with high agility requirements, it can be advantageous because these control loops can be closed with a higher frequency as if would be possible with a centralized external attitude controller. The system is characterized by a low steady-state power consumption of 220 mW at the zero motor speed and under 1.5 W at the maximum speed, has the dimensions of 65 x 65 x 55 mm3 and a weight of less than 320 g. Two wheel modifications for different satellite classes with slightly different rotor geometry exist. The angular momentum can be as high as 45 mNms. The modular design allows a scale-up without significant changes in mechanics and electronics. Finally, future work based on the described design is discussed

Verfahren zur Vermeidung von Kollisionen gesteuert beweglicher Teile einer Anlage

Dieser technische Bericht beschreibt das Verfahren zur Vermeidung von Kollisionen gesteuert beweglicher Teile einer Anlage, wie es durch das Deutsche Forschungszentrum für künstliche Intelligenz beim Deutschen Patentamt unter 102009006256.4-32 zum Patent [1] angemeldet wurde. Das Verfahren dient der zentralen Überwachung bewegter Anlagenteile (u.a. Roboterarme und Fahrzeuge) zum Schutz vor Kollisionen mit einander oder mit der Umwelt. Es ist entsprechend mit und ohne die zusätzliche sensorielle Erfassung von Hindernissen einsetzbar. Wesentlicher Bestandteil des Algorithmus ist die Darstellung des von einem bewegten Anlagenteil während seiner Bewegung überstrichenen Volumens in Form der konvexen Hülle einer endlichen Punktmenge zzgl. eines Pufferradius. Diese Darstellung ist robust und in Echtzeit ohne numerische Probleme berechenbar. Die Darstellung wird für alle involvierten Körper berechnet und anschließend dazu verwendet, alle relevanten Paare von Körpern oder die sensoriell erfassten Bereiche der Umwelt auf Kollisionen zu testen. Dazu wird ein neuer und echtzeitfähiger Algorithmus angegeben. Alle Berechnungen werden mittels konservativer Abschätzungen durchgeführt, so dass ein mathematisch beweisbar sicheres Gesamtsystem entsteht. Es werden einige solcher konservativer Abschätzungen für unterschiedliche Teile einer bewegten Anlage angegeben, die es dem Anwender des Verfahrens ermöglichen, bei der Beschreibung der Anlagengeometrie und —kinematik zwischen einer möglichst exakten Modellierung und einer einfacher und schneller berechnenbaren zu variieren. Für Fahrzeugtrajektorien (z.B. Bremsbewegungen) wird außerdem ein Konfigurationsraum verwendet, der es erlaubt Kurven- und Kreisfahrten einheitlich und ohne Singularitäten zu modellieren.This technical report describes the collsion avoidance method emph{Verfahren zur Vermeidung von Kollisionen gesteuert beweglicher Teile einer Anlage} as applied for a patent by the German Research Center for Artificial Intelligence under No. text{102009006256.4-32}. The method allows to centrally monitor moveable parts of a machine (e.g. robot arms or vehicles) and so avoids collisions among the machine parts or with the environment. For this it can be used with or without additional sensorial perception of the environment. A basic idea of the described method is representing the volume touched by one part of a machine while its movement as the convex hull of a finite set of points expanded by a buffer radius. This representation is robust, real-time computable, and does not have numerical difficulties. The representation is computed for all involved parts of the machine. Afterwards all relevant pairs of volumes, or the sensed environment respectively, are checked for collisions. To do this, a new real-time algorithm is presented. All computations performed by the method are conservative approximations, which results in the system as a whole being safe in a strict mathematical sense. The technical report offers a couple of versions for these conservative approximations. With this set of approximations the user is enabled to trade a more exact model of his machine against a more easier and faster one. Concerning vehicle trajectories (e.g. braking trajectories) the usage of a new configuration space is described also. Its main advantage is a joint modeling of straight and circular trajectories and even turning on the spot without singularities, which for instance occur with radius or curvature as parameter

(A) Vision for 2050 - Context-Based Image Understanding for a Human-Robot Soccer Match

We believe it is possible to create the visual subsystem needed for the RoboCup 2050 challenge - a soccer match between humans and robots - within the next decade.  In this position paper, we argue, that the basic techniques are available, but the main challenge will be to achieve the necessary robustness. We propose to address this challenge through the use of probabilistically modeled context, so for instance a visually indistinct circle is  accepted as the ball, if it fits well with the ball's motion model and vice versa.Our vision is accompanied by a sequence of (partially already conducted) experiments for its verification.  In these experiments, a human soccer player carries a helmet with a camera and an inertial sensor and the vision system has to extract all information from that data, a humanoid robot would need to take the human's place

In Time and Space: Towards Usable Adaptive Control for Assistive Robotic Arms

Robotic solutions, in particular robotic arms, are becoming more frequently deployed for close collaboration with humans, for example in manufacturing or domestic care environments. These robotic arms require the user to control several Degrees-of-Freedom (DoFs) to perform tasks, primarily involving grasping and manipulating objects. Standard input devices predominantly have two DoFs, requiring time-consuming and cognitively demanding mode switches to select individual DoFs. Contemporary Adaptive DoF Mapping Controls (ADMCs) have shown to decrease the necessary number of mode switches but were up to now not able to significantly reduce the perceived workload. Users still bear the mental workload of incorporating abstract mode switching into their workflow. We address this by providing feed-forward multimodal feedback using updated recommendations of ADMC, allowing users to visually compare the current and the suggested mapping in real-time. We contrast the effectiveness of two new approaches that a) continuously recommend updated DoF combinations or b) use discrete thresholds between current robot movements and new recommendations. Both are compared in a Virtual Reality (VR) in-person study against a classic control method. Significant results for lowered task completion time, fewer mode switches, and reduced perceived workload conclusively establish that in combination with feedforward, ADMC methods can indeed outperform classic mode switching. A lack of apparent quantitative differences between Continuous and Threshold reveals the importance of user-centered customization options. Including these implications in the development process will improve usability, which is essential for successfully implementing robotic technologies with high user acceptance

AdaptiX -- A Transitional XR Framework for Development and Evaluation of Shared Control Applications in Assistive Robotics

With the ongoing efforts to empower people with mobility impairments and the increase in technological acceptance by the general public, assistive technologies, such as collaborative robotic arms, are gaining popularity. Yet, their widespread success is limited by usability issues, specifically the disparity between user input and software control along the autonomy continuum. To address this, shared control concepts provide opportunities to combine the targeted increase of user autonomy with a certain level of computer assistance. This paper presents the free and open-source AdaptiX XR framework for developing and evaluating shared control applications in a high-resolution simulation environment. The initial framework consists of a simulated robotic arm with an example scenario in Virtual Reality (VR), multiple standard control interfaces, and a specialized recording/replay system. AdaptiX can easily be extended for specific research needs, allowing Human-Robot Interaction (HRI) researchers to rapidly design and test novel interaction methods, intervention strategies, and multi-modal feedback techniques, without requiring an actual physical robotic arm during the early phases of ideation, prototyping, and evaluation. Also, a Robot Operating System (ROS) integration enables the controlling of a real robotic arm in a PhysicalTwin approach without any simulation-reality gap. Here, we review the capabilities and limitations of AdaptiX in detail and present three bodies of research based on the framework. AdaptiX can be accessed at https://adaptix.robot-research.de.Comment: Accepted submission at The 16th ACM SIGCHI Symposium on Engineering Interactive Computing Systems (EICS'24

Serine-Rich Repeat Protein adhesins from Lactobacillus reuteri display strain specific glycosylation profiles

Lactobacillus reuteri is a gut symbiont inhabiting the gastrointestinal tract of numerous vertebrates. The surface-exposed Serine-Rich Repeat Protein (SRRP) is a major adhesin in Gram-positive bacteria. Using lectin and sugar nucleotide profiling of wild-type or L. reuteri isogenic mutants, MALDI-ToF-MS, LC-MS and GC-MS analyses of SRRPs, we showed that L. reuteri strains 100-23C (from rodent) and ATCC 53608 (from pig) can perform protein O-glycosylation and modify SRRP100-23 and SRRP53608 with Hex-Glc-GlcNAc and di-GlcNAc moieties, respectively. Furthermore, in vivo glycoengineering in E. coli led to glycosylation of SRRP53608 variants with α-GlcNAc and GlcNAcβ(1→6)GlcNAcα moieties. The glycosyltransferases involved in the modification of these adhesins were identified within the SecA2/Y2 accessory secretion system and their sugar nucleotide preference determined by saturation transfer difference NMR spectroscopy and differential scanning fluorimetry. Together, these findings provide novel insights into the cellular O-protein glycosylation pathways of gut commensal bacteria and potential routes for glycoengineering applications