Evaluation of H-infinity Filter in Time Differential Localization Systems

This paper evaluates the performances of H-infinity filter in differential time of arrival (TDoA) localization applications and compares the results with other filters such as extended Kalman filter (EKF) and unscented Kalman filter (UKF) in practical trials. The filters are compared in ideal as well as non-ideal conditions such as different positive and negative values of initial points, presence of erroneous data and excessive noise. The results show that, the H-infinity filter is sub-optimal in ideal conditions as the other filters outperform this filter, but once the initial points are badly selected or data are erroneous, the filter is more robust and accurate than the other variants. Considering the challenging conditions of the indoor environment, use of this filter in localization systems seems to be a good choice

Anchor Pair Selection in Unilateral TDoA Localization Topologies

This paper addresses the pair selection problem of the unilateral time difference of arrival (TDoA) localization method. Two common concepts of pair selection are star form which uses a unique reference node for pairing all nodes and the chain form which links each node to its next available node. The problem of the star form is the possibility of occurring non-line of sight (NLOS) conditions between some anchors. The chain form has an issue with increasing variance of the noise as the number of anchors increases. A new hybrid form is proposed which avoids NLOS conditions and at the same time pertains the amount of noise at its minimum possible. Practical results confirm the superior performance of the proposed approach

Teleworkbench: An Analysis Tool for Multi-Robotic Experiments

Tanoto A, Du JL, Witkowski U, Rückert U. Teleworkbench: An Analysis Tool for Multi-Robotic Experiments. In: Proceedings of the IFIP Conference on Biologically Inspired Cooperative Computing (BICC 2006), 19th World Computer Congress (WCC). Santiago, Chile; 2006.This paper presents a tool, one component of the Teleworkbench system, for analyzing experiments in multi-robotics. The proposed tool combines the video taken by a web cam monitoring the field where the experiment runs and some computer generated visual objects representing important events and information as well as robots’ behavior into one interactive video based on MPEG-4 standard. Visualization and data summarization enables the developer to quickly grasp a situation, whereas the possibility of scrolling through the video and selectively activating information helps him analyzing interesting events in depth. Because of the MPEG-4 standard used for the output video, the analysis process can be done in a wide range of platforms. This trait is beneficial for education and research cooperation purposes

A robot swarm assisting a human fire-fighter

Emergencies in industrial warehouses are a major concern for fire-fighters. The large dimensions, together with the development of dense smoke that drastically reduces visibility, represent major challenges. The GUARDIANS robot swarm is designed to assist fire-fighters in searching a large warehouse. In this paper we discuss the technology developed for a swarm of robots assisting fire-fighters. We explain the swarming algorithms that provide the functionality by which the robots react to and follow humans while no communication is required. Next we discuss the wireless communication system, which is a so-called mobile ad-hoc network. The communication network provides also the means to locate the robots and humans. Thus, the robot swarm is able to provide guidance information to the humans. Together with the fire-fighters we explored how the robot swarm should feed information back to the human fire-fighter. We have designed and experimented with interfaces for presenting swarm-based information to human beings

Vascular miR‐181b controls tissue factor‐dependent thrombogenicity and inflammation in type 2 diabetes

BACKGROUND: Diabetes mellitus is characterized by chronic vascular inflammation leading to pathological expression of the thrombogenic full length (fl) tissue factor (TF) and its isoform alternatively-spliced (as) TF. Blood-borne TF promotes factor (F) Xa generation resulting in a pro-thrombotic state and cardiovascular complications. MicroRNA (miR)s impact gene expression on the post-transcriptional level and contribute to vascular homeostasis. Their distinct role in the control of the diabetes-related procoagulant state remains poorly understood. METHODS: In a cohort of patients with poorly controlled type 2 diabetes (n = 46) plasma levels of miR-181b were correlated with TF pathway activity and markers for vascular inflammation. In vitro, human microvascular endothelial cells (HMEC)-1 and human monocytes (THP-1) were transfected with miR-181b or anti-miR-181b and exposed to tumor necrosis factor (TNF) α or lipopolysaccharides (LPS). Expression of TF isoforms, vascular adhesion molecule (VCAM) 1 and nuclear factor (NF) κB nuclear translocation was assessed. Moreover, aortas, spleen, plasma, and bone marrow-derived macrophage (BMDM)s of mice carrying a deletion of the first miR-181b locus were analyzed with respect to TF expression and activity. RESULTS: In patients with type 2 diabetes, plasma miR-181b negatively correlated with the procoagulant state as evidenced by TF protein, TF activity, D-dimer levels as well as markers for vascular inflammation. In HMEC-1, miR-181b abrogated TNFα-induced expression of flTF, asTF, and VCAM1. These results were validated using the anti-miR-181b. Mechanistically, we confirmed a miR-181b-mediated inhibition of importin-α3 (KPNA4) leading to reduced nuclear translocation of the TF transcription factor NFκB. In THP-1, miR-181b reduced both TF isoforms and FXa generation in response to LPS due to targeting phosphatase and tensin homolog (PTEN), a principal inducer for TF in monocytes. Moreover, in miR-181-/- animals, we found that reduced levels of miR-181b were accompanied by increased TF, VCAM1, and KPNA4 expression in aortic tissue as well as increased TF and PTEN expression in spleen. Finally, BMDMs of miR-181-/- mice showed increased TF expression and FXa generation upon stimulation with LPS. CONCLUSIONS: miR-181b epigenetically controls the procoagulant state in diabetes. Reduced miR-181b levels contribute to increased thrombogenicity and may help to identify individuals at particular risk for thrombosis

The Mini-Robot Khepera as a Foraging Animate: Synthesis and Analysis of Behaviour

Löffler A, Klahold J, Rückert U. The Mini-Robot Khepera as a Foraging Animate: Synthesis and Analysis of Behaviour. In: Rückert U, Sitte J, Witkowski U, eds. Proceedings of the 5th International Heinz Nixdorf Symposium: Autonomous Minirobots for Research and Edutainment (AMiRE01). Vol 97. Paderborn, Germany: Heinz Nixdorf Institut, Universität Paderborn; 2001: 93-130.The work presented in this paper deals with the development of a methodology for resource-efficient behaviour synthesis on autonomous systems. In this context, a definition of a maximal problem with respect to the resources of a given system is introduced. It is elucidated by means of an exemplary implementation of the solution to such a problem using the mini-robot Khepera as the experimental platform. The described task consists of exploring an unknown and dynamically changing environment, collecting and transporting objects, which are associated with light-sources, and navigating to a home-base. The critical point is represented by the accumulated positioning errors in odometrical path-integration due to slippage. Therefore, adaptive sensor calibration using a specific variant of Kohonen’s algorithm is applied in two cases to extract symbolic, e.g. geometric, information from the sub-symbolic sensor data, which is used to enhance position control by landmark mapping and orientation. In order to successfully handle the arising complex interactions, a heterogeneous control-architecture based on a parallel implementation of basic behaviours coupled by a rule-based central unit is proposed

MicroRNA-19a contributes to the epigenetic regulation of tissue factor in diabetes

Background: Diabetes mellitus is characterized by chronic vascular disorder and presents a main risk factor for cardiovascular mortality. In particular, hyperglycaemia and inflammatory cytokines induce vascular circulating tissue factor (TF) that promotes pro-thrombotic conditions in diabetes. It has recently become evident that alterations of the post-transcriptional regulation of TF via specific microRNA(miR)s, such as miR-126, contribute to the pathogenesis of diabetes and its complications. The endothelial miR-19a is involved in vascular homeostasis and atheroprotection. However, its role in diabetes-related thrombogenicity is unknown. Understanding miR-networks regulating procoagulability in diabetes may help to develop new treatment options preventing vascular complications. Methods and results: Plasma of 44 patients with known diabetes was assessed for the expression of miR-19a, TF protein, TF activity, and markers for vascular inflammation. High miR-19a expression was associated with reduced TF protein, TF-mediated procoagulability, and vascular inflammation based on expression of vascular adhesion molecule-1 and leukocyte count. We found plasma expression of miR-19a to strongly correlate with miR-126. miR-19a reduced the TF expression on mRNA and protein level in human microvascular endothelial cells (HMEC) as well as TF activity in human monocytes (THP-1), while anti-miR-19a increased the TF expression. Interestingly, miR-19a induced VCAM expression in HMEC. However, miR-19a and miR-126 co-transfection reduced total endothelial VCAM expression and exhibited additive inhibition of a luciferase reporter construct containing the F3 3′UTR. Conclusions: While both miRs have differential functions on endothelial VCAM expression, miR-19a and miR-126 cooperate to exhibit anti-thrombotic properties via regulating vascular TF expression. Modulating the post-transcriptional control of TF in diabetes may provide a future anti-thrombotic and anti-inflammatory therapy

Communication Between Khepera Mini Robots For Cooperative Positioning

Grünewald M, Iske B, Klahold J, et al. Communication Between Khepera Mini Robots For Cooperative Positioning. In: Proceedings of the International Conference Automatics and Informatics’03. Vol 1. Sofia, Bulgaria; 2003: 95-98

Teleworkbench: an analysis tool for multi-robotic experiments

This paper presents a tool, one component of the Teleworkbench system, for analyzing experiments in multi-robotics. The proposed tool combines the video taken by a web cam monitoring the field where the experiment runs and some computer generated visual objects representing important events and information as well as robots’ behavior into one interactive video based on MPEG-4 standard. Visualization and data summarization enables the developer to quickly grasp a situation, whereas the possibility of scrolling through the video and selectively activating information helps him analyzing interesting events in depth. Because of the MPEG-4 standard used for the output video, the analysis process can be done in a wide range of platforms. This trait is beneficial for education and research cooperation purposes.1st IFIP International Conference on Biologically Inspired Cooperative Computing - Robotics and Sensor NetworksRed de Universidades con Carreras en Informática (RedUNCI