TY - JOUR A1 - Ullner, Christian A1 - Subaric-Leitis, Andreas A1 - Bartholmai, Matthias T1 - Uncertainty of Elastoplastic Material Parameters Calculated from the Spherical Indentation in the Macro Range JF - Journal of Testing and Evaluation N2 - The applicability of three methods developed by finite element analysis (FEM) and proposed in the literature are studied on steel S355. Instrumented indentation tests using spherical indenters of radius 200 and 500 μ m are performed in the macro range at depths of more than 6 μ m. The results of the selected methods are compared with the tensile test. To evaluate the partially strongly varying results, the uncertainties of the calculated strain hardening exponent, n, and yield stress, Y, are estimated. Recommendations for an appropriated procedure of the indentation test are given. The machine compliance and the determination of the zero point of Depth play an essential role. If the certain conditions are considered, the instrumented indentation Tests can be used, in particular for investigations of specimens with inhomogeneous elastoplasticity. KW - Indentation KW - Elastoplastic material parameters KW - Uncertainty PY - 2021 DO - https://doi.org/10.1520/JTE20200683 SN - 0090-3973 VL - 49 IS - 6 SP - 4576 EP - 4592 PB - ASTM International AN - OPUS4-52416 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strangfeld, Christoph A1 - Johann, Sergej A1 - Bartholmai, Matthias T1 - Smart RFID Sensors Embedded in Building Structures for Early Damage Detection and Long-Term Monitoring JF - Sensors N2 - In civil engineering, many structures are made of reinforced concrete. Most Degradation processes relevant to this material, e.g., corrosion, are related to an increased level of material moisture. Therefore, moisture monitoring in reinforced concrete is regarded as a crucial method for structural health monitoring. In this study, passive radio frequency identification (RFID)-based sensors are embedded into the concrete. They are well suited for long-term operation over decades and are well protected against harsh environmental conditions. The energy supply and the data transfer of the humidity sensors are provided by RFID. The sensor casing materials are optimised to withstand the high alkaline environment in concrete, having pH values of more than 12. Membrane materials are also investigated to identify materials capable of enabling water vapour transport from the porous cement matrix to the embedded humidity sensor. By measuring the corresponding relative humidity with embedded passive RFID-based sensors, the cement hydration is monitored for 170 days. Moreover, long-term moisture monitoring is performed for more than 1000 days. The Experiments show that embedded passive RFID-based sensors are highly suitable for long-term structural health monitoring in civil engineering. KW - RFID based sensors KW - Embedded sensors KW - Corresponding relative humidity KW - Porous building materials KW - Reinforced concrete KW - Corrosion KW - Civil engineering PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-500831 DO - https://doi.org/10.3390/s19245514 VL - 19 IS - 24 SP - 1 EP - 18 PB - MDPI CY - Basel, Swiss AN - OPUS4-50083 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schukar, Vivien A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Mitzkus, Anja A1 - Gong, Xin A1 - Sahre, Mario A1 - Bartholmai, Matthias A1 - Beck, Uwe ED - Emri, Igor T1 - A contribution to intelligent automatic validation of structure-integrated fibre optic strain sensors JF - Materials Today: Proceedings N2 - An auto-validation tool for the reliability quantification of materials integrated fiber Bragg grating (FBG) strain sensors have been developed and tested. The FBG strain sensor was jacketed with a magnetostrictive layer based on iron-nickel which, when excited by a specific magnetic field, adds an artificial strain to the sensor. The fixed relationship between magnetic induction and wavelength shift of the FBG strain sensor characterizes the bond strength and adhesion between the sensor and the surrounding structure. Due to an easily applicable magnetic field, it is possible to validate the sensor performance in a non-contact, fast way without disturbing the data-acquisition process. T2 - 33nd Danubia Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Fiber Bragg grating KW - Self-diagnosis KW - Magnetostriction KW - Strain KW - Auto-validation PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S2214785317308489 DO - https://doi.org/10.1016/j.matpr.2017.06.073 SN - 2214-7853 VL - 4 IS - 5, Part 1 SP - 5935 EP - 5939 PB - Elsevier Ltd. AN - OPUS4-41583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard A1 - Kunze, Ralf A1 - Bartholmai, Matthias A1 - Neubert, Dietmar A1 - Schriever, Robert T1 - TG-MS and TG-FTIR applied for an unambiguous thermal analysis of intumescent coatings JF - Journal of thermal analysis and calorimetry N2 - Thermogravimetry (TG), thermogravimetry coupled with mass spectroscopy (TG-MS) and thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR) were used to characterise the thermo-oxidative behaviour of two intumescent coating materials. The temperature dependence, the corresponding volatile products and the amount of residue of the different processes were determined. Using both TG-MS and TG-FTIR results in an unambiguous interpretation of the volatile products. Characteristics such as the influence of endothermic reactions, the release of non-flammable gases, the dehydrogenation enhancing the char formation and the stability of the cellular char were discussed in detail. It was demonstrated, that TG, TG-MS and TG-FTIR are powerful methods to investigate mechanisms in intumescent coatings and that they are suitable methods in respect to quality assurance and unambiguous identification of such materials. KW - Intumescent coating materials KW - TG KW - TG-FTIR KW - TG-MS PY - 2002 DO - https://doi.org/10.1023/A:1022272707412 SN - 1388-6150 SN - 1418-2874 SN - 0368-4466 SN - 1572-8943 VL - 70 IS - 3 SP - 897 EP - 909 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-2133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard A1 - Braun, Ulrike A1 - Knoll, Uta A1 - Bartholmai, Matthias A1 - Goering, Harald A1 - Neubert, Dietmar A1 - Pötschke, P. T1 - Mechanical, Thermal, and Fire Behavior of Bisphenol A Polycarbonate/Multiwall Carbon Nanotube Nanocomposites JF - Polymer engineering & science N2 - Nanocomposites of bisphenol A polycarbonate with 2, 4, 6, and 15 wt% multiwall carbon nanotubes (MWNT) and their use in fire retardancy are investigated. Their thermal behavior and pyrolysis are characterized using thermogravimetry, differential scanning calorimeter, oscillatory shear rheology, and dynamic mechanical analysis. The flammability is addressed using LOI and UL 94; the fire behavior, with a cone calorimeter using different irradiation. With increasing MWNT content the storage modulus is increased (10-20%) and melt viscosity increases by several orders of magnitude, particularly for low shear rates. The melt flow, dripping, and deformation during fire are hindered, which influences UL 94 and cone calorimeter results. The peak heat release rate is reduced up to 40-50% due to an improved barrier for small amounts (2 wt%) of MWNT and for low irradiation, whereas the effect is reduced for increasing irradiation and nearly vanishes for increasing filling. Adjuvant but also deleterious mechanisms result in the complex dependency on the MWNT content. Significant flame retardancy effects are specific and limited to only some fire properties. This study allows the materials' potential for implementation in different fire scenarios and tests to be assessed and provides insight into active mechanisms. KW - Flame retardancy KW - Nanocomposite KW - Carbon multiwall nanotube (MWNT) KW - Cone Caorimeter KW - Flammability PY - 2008 DO - https://doi.org/10.1002/pen.20932 SN - 0032-3888 SN - 1548-2634 VL - 48 IS - 1 SP - 149 EP - 158 PB - Wiley CY - Hoboken, NY AN - OPUS4-16365 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard A1 - Bartholmai, Matthias A1 - Knoll, Uta T1 - Some comments on the main fire retardancy mechanisms in polymer nanocomposites JF - Polymers for advanced technologies N2 - Barrier formation and increasing the melt viscosity are addressed as the two main general fire retardancy mechanisms of polymer nanocomposites. They result in specific impacts on fire properties that consequentially cause varying flame retardancy efficiency in different fire tests. The barrier formation retards mainly flame spread (peak of heat release rate) in developing fires, but does not reduce fire load (total heat evolved), ignitability or flammability (limiting oxygen index, UL 94). Furthermore, this flame retardancy effect increases with increasing irradiation and vanishes with decreasing irradiation. The increased melt viscosity prevents dripping, which is beneficial or disadvantageous depending on the fire test used. In some test, it become the dominant influence, transforming self-extinguishing samples into flammable materials or causing wicking. Advantages and the limits are sketched comprehensively for exploiting the main general fire retardancy mechanisms of polymer nanocomposites. It is concluded that barrier formation and changing the melt viscosity in nanocomposites are not sufficient for most applications, but must be accompanied by additional mechanisms in special systems or in combination with other flame retardants. KW - Flame retardance KW - Nanocomposites KW - Organoclay KW - Cone calorimeter KW - Flammability PY - 2006 DO - https://doi.org/10.1002/pat.792 SN - 1042-7147 SN - 1099-1581 VL - 17 IS - 9-10 SP - 772 EP - 777 PB - John Wiley & Sons, Ltd. CY - Chichester AN - OPUS4-13868 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schartel, Bernhard A1 - Bartholmai, Matthias A1 - Knoll, Uta T1 - Some comments on the use of cone calorimeter data JF - Polymer degradation and stability N2 - The cone calorimeter has become one of the most important and widely used instruments for the research and development of fire retarded polymeric materials. The paper addresses three important ways in which the principal setup influences the results — factors which sometimes do not receive due consideration when drawing conclusions. The paper discusses in detail the impact on cone calorimeter results of the choice of external heat flux, the influence on the peak of heat release rate of sample thickness and thermal feedback from the back of the sample, and the influence on irradiance of the horizontal and vertical distances from the cone heater. KW - Cone Calorimeter KW - Fire retardancy KW - Fire testing KW - Nanocomposites KW - Intumescence PY - 2005 DO - https://doi.org/10.1016/j.polymdegradstab.2004.12.016 SN - 0141-3910 SN - 1873-2321 VL - 88 IS - 3 SP - 540 EP - 547 PB - Applied Science Publ. CY - London AN - OPUS4-7211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Petrov, Sergej A1 - Neumann, Patrick P. A1 - Werner, Klaus-Dieter A1 - Wosniok, Aleksander A1 - Lazik, D. A1 - Bartholmai, Matthias ED - Nicoletto, G. ED - Pastrama, S.D. ED - Emri, I. T1 - Concept for investigating mechanical and thermal impacts on distributed subsurface gas monitoring JF - Materials Today: Proceedings N2 - A multifunctional sensor in line shape was developed and introduced in previous work for measuring of gas concentrations, temperature change, and strain. A current field study focuses on a spatially distributed monitoring of subsurface CO 2 gas storage sites in near real time. Mechanical impacts, e.g., caused by construction work, denudation, and seismic activity, can affect the integrity of underground gas storage sites. Thermal or moisture impacts, e.g., caused by weather conditions, can influence the gas Distribution behavior. In this paper, we briefly describe the setup of a CO 2 injection soil test field. This setup contains actuating elements for the investigation of mechanical and thermal impacts on distributed subsurface gas monitoring. A concept is given for evaluating these impacts and first experimental results are presented. T2 - 32nd DANUBIA ADRIA SYMPOSIUM on Advances in Experimental Mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 KW - Linear sensor KW - Distributed sensor KW - Monitoring of CO 2 KW - Subsurface monitoring KW - Gas storage areas KW - Membrane-based gas sensing KW - Fibre optical sensing PY - 2016 DO - https://doi.org/10.1016/j.matpr.2016.03.060 SN - 2214-7853 VL - 3 IS - 4 SP - 1124 EP - 1128 PB - Elsevier Ltd. AN - OPUS4-35688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Werner, Klaus-Dieter A1 - Petrov, Sergej A1 - Bartholmai, Matthias A1 - Lazik, D. ED - Puente León, F. ED - Zagar, B. T1 - Aufbau eines großflächigen Testfeldes für verteilte Bodengassensorik und Untersuchung einer Monitoringmethode basierend auf Tomographie T1 - Setup of a large-scale test field for distributed soil gas sensors and testing of a monitoring method based on tomography JF - tm - Technisches Messen N2 - A 400 m² soil test field with gas injection system was built up for the purpose of large-scale validation, optimization, and characterization of a novel comprehensive monitoring method for underground gas storage areas. The method combines gas sensing technology with linear form factor for in-situ monitoring of gases in soil with the mapping capabilities of Computed Tomography (CT) to reconstruct time-series of gas distribution maps based on samples of orthogonally-aligned linear gas sensors. Several injection experiments with carbon dioxide (CO2) at different days with varying boundary conditions indicates the potential of the method for, e.g., rapid leakage detection with respect to Carbon Capture and Storage (CCS) issues. N2 - Zur Validierung, Optimierung und praxisnahen Demonstration eines flächendeckenden Monitoringverfahrens für Untergrundgasspeichern wurde ein 400 m² großes Testfeld mit Gasinjektionssystem auf dem BAM Testgelände Technische Sicherheit aufgebaut. Die Methode kombiniert verteilte, linienförmige Gassensorik für die In-situ-Überwachung von Gasen im Boden mit den Mapping-Fähigkeiten der Computertomographie (CT). Auf Basis von orthogonal zueinander ausgerichteten linearen Gassensoren können mit diesem Verfahren so Zeitreihen der Gasverteilung rekonstruiert werden. Experimente mit Kohlendioxid (CO2) zeigen das Potential des Verfahrens zur schnellen Lokalisierung von Leckagen auf. KW - Soil test field KW - Distributed linear sensor KW - Membrane-based gas sensing KW - Subsurface monitoring KW - Gas storage areas KW - Computed tomography PY - 2016 DO - https://doi.org/10.1515/teme-2016-0015 SN - 2196-7113 SN - 0171-8096 VL - 83 IS - 10 SP - 606 EP - 615 PB - Walter de Gruyter GmbH CY - Berlin, Deutschland AN - OPUS4-37653 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Schnürmacher, M. A1 - Bennetts, V.H. A1 - Lilienthal, A.J. A1 - Bartholmai, Matthias A1 - Schiller, J.H. T1 - A probabilistic gas patch path prediction approach for airborne gas source localization in non-uniform wind fields JF - Sensor letters N2 - In this paper, we show that a micro unmanned aerial vehicle (UAV) equipped with commercially available gas sensors can address environmental monitoring and gas source localization (GSL) tasks. To account for the challenges of gas sensing under real-world conditions, we present a probabilistic approach to GSL that is based on a particle filter (PF). Simulation and real-world experiments demonstrate the suitability of this algorithm for micro UAV platforms. KW - Autonomous micro UAV KW - Chemical and wind sensing KW - Gas source localization KW - Particle filter PY - 2014 DO - https://doi.org/10.1166/sl.2014.3168 SN - 1546-198X SN - 1546-1971 VL - 12 IS - 6/7 SP - 1113 EP - 1118 PB - American Scientific Publishers (ASP) CY - Stevenson Ranch, CA, USA AN - OPUS4-31525 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Lazik, D. A1 - Bartholmai, Matthias T1 - Tomographic reconstruction of soil gas distribution from multiple gas sources based on sparse sampling JF - IEEE Sensors Journal N2 - A monitoring method is introduced that creates twodimensional (2D) maps of the soil gas distribution. The method combines linear gas sensing technology for in-situ monitoring of gases in soil with the mapping capabilities of Computed Tomography (CT) to reconstruct spatial and temporal resolved gas distribution maps. A weighted iterative algebraic reconstruction method based on Maximum Likelihood with Expectation Maximization (MLEM) in combination with a source-by-source reconstruction approach is introduced that works with a sparse setup of orthogonally-aligned linear gas sensors. The reconstruction method successfully reduces artifact production, especially when multiple gas sources are present, allowing the discrimination between true and non-existing so-called ghost source locations. Experimental validation by controlled field experiments indicates the high potential of the proposed method for rapid gas leak localization and quantification with respect to Pipeline or underground gas storage issues. KW - Computed tomography KW - Gas distribution mapping and gas source localization KW - Discrimination of multiple gas sources KW - Distributed linear sensor KW - Membrane-based gas sensing KW - Subsurface monitoring KW - Gas storage areas PY - 2016 DO - https://doi.org/10.1109/JSEN.2016.2545103 SN - 1530-437X VL - 16 IS - 11 SP - 4501 EP - 4508 PB - IEEE - Inst. Electrical Electronics Engineers Inc CY - Hoes Lane, NJ, USA AN - OPUS4-36228 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Lazik, D. A1 - Bartholmai, Matthias ED - Emri, Igor T1 - Validation of membrane-based linear soil gas sensors under field conditions JF - MATERIALS TODAY-PROCEEDINGS N2 - A 400 m2 soil test field with gas injection system was built up, which enables an experimental validation of linear membrane-based gas sensors – a sensor technology which was developed based on the selective permeation of gases through membranes. Several soil watering and injection experiments with carbon dioxide at different days with varying boundary conditions were performed showing that the sensor behaves mostly insensitive to the environmental conditions investigated, i.e., barometric pressure fluctuations, soil temperature, air temperature and humidity, sun duration, and wind speed. Furthermore, depending on water infiltration, a gas phase displacement could be observed in-situ based on the changed measurement signal. The results of the validation experiments highlight the potential of the method for rapid leak detection and localization qualifying the sensor particularly for safety applications, e.g., in underground gas storage areas. T2 - 33nd Danubia Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Distributed linear sensor KW - Membrane-based gas sensing KW - Subsurface monitoring KW - Gas storage areas KW - Validation PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S2214785317308404 DO - https://doi.org/10.1016/j.matpr.2017.06.065 SN - 2214-7853 VL - 4 IS - 5, Part 1 SP - 5893 EP - 5897 PB - Elsevier Ltd. AN - OPUS4-41584 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Kohlhoff, Harald A1 - Hüllmann, Dino A1 - Krentel, Daniel A1 - Kluge, Martin A1 - Dzierliński, M. A1 - Lilienthal, A. J. A1 - Bartholmai, Matthias T1 - Aerial-based gas tomography – from single beams to complex gas distributions JF - European Journal of Remote Sensing N2 - In this paper, we present and validate the concept of an autonomous aerial robot to reconstruct tomographic 2D slices of gas plumes in outdoor environments. Our platform, the so-called Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS), combines a lightweight Tunable Diode Laser Absorption Spectroscopy (TDLAS) gas sensor with a 3-axis aerial stabilization gimbal for aiming at a versatile octocopter. While the TDLAS sensor provides integral gas concentration measurements, it does not measure the distance traveled by the laser diode’s beam nor the distribution of gas along the optical path. Thus, we complement the set-up with a laser rangefinder and apply principles of Computed Tomography (CT) to create a model of the spatial gas distribution from a set of integral concentration measurements. To allow for a fundamental ground truth evaluation of the applied gas tomography algorithm, we set up a unique outdoor test environment based on two 3D ultrasonic anemometers and a distributed array of 10 infrared gas transmitters. We present results showing its performance characteristics and 2D plume reconstruction capabilities under realistic conditions. The proposed system can be deployed in scenarios that cannot be addressed by currently available robots and thus constitutes a significant step forward for the field of Mobile Robot Olfaction (MRO). KW - Aerial robot olfaction KW - Mobile robot olfaction KW - Gas tomography KW - TDLAS KW - Plume PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-487843 DO - https://doi.org/10.1080/22797254.2019.1640078 SP - 1 EP - 16 PB - Taylor & Francis CY - London AN - OPUS4-48784 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Hüllmann, Dino A1 - Bartholmai, Matthias ED - Pastramă, Ş. D. ED - Constantinescu, D. M. T1 - Concept of a gas-sensitive nano aerial robot swarm for indoor air quality monitoring JF - Materials Today: Proceedings N2 - In this paper, we introduce a nano aerial robot swarm for indoor air quality monitoring applications such as occupational health and safety of (industrial) workplaces. The concept combines a robotic swarm composing of nano Unmanned Aerial Vehicles (nano UAVs), based on the Crazyflie 2.0 quadrocopter, and small lightweight metal oxide gas sensors for measuring the Total Volatile Organic Compound (TVOC) in ppb and estimating the eCO2 (equivalent calculated carbon-dioxide) concentration in ppm. TVOC is a measure for the indoor air quality. An indoor localization and positioning system will be used to estimate the absolute 3D position of the swarm like GPS. Based on this novel indoor air quality monitoring concept, the development and validation of new algorithms in the field of Mobile Robot Olfaction (MRO) are planned, namely gas source localization and gas distribution mapping. A test scenario will be built up to validate and optimize the gas-sensitive nano aerial robot swarm for the intended applications. T2 - 35th Danubia Adria Symposium on Advances in Experimental Mechanics CY - Sinaia, Romania DA - 25.09.2018 KW - Nano aerial robot KW - UAV KW - Swarm KW - Indoor air quality KW - Monitoring KW - Concept PY - 2019 DO - https://doi.org/10.1016/j.matpr.2019.03.151 SN - 2214-7853 VL - 12 IS - 2 SP - 470 EP - 473 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-48055 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Hirschberger, Paul A1 - Bartholmai, Matthias ED - Holl, H. T1 - Flying ant robot for chemical trail detection and localization JF - Materials Today: Proceedings N2 - This paper presents first advances in the area of aerial chemical trail following. For that purpose, we equipped a palm-size aerial robot, based on the Crazyflie 2.0 quadrocopter, with a small lightweight metal oxide gas sensor for measuring evaporated ethanol from chemical trails. To detect and localize a 5 cm wide chemical trail, a detection criterion was developed that uses only relative changes in the transient phase of the sensor response. The reduction in signal strength dependence improves the robustness of its application. We tested our setup in first crossing-trail experiments showing that our flying ant robot can correlate an odor hit with the chemical trail within 0.14 m. Principally, this could enable aerial chemical trail following in the future. T2 - 37th Danubia - Adria Symposium on Advances in Experimental Mechanics CY - Linz, Austria DA - 21.09.2021 KW - Aerial robot KW - Trail following KW - Trail detection KW - Localization PY - 2022 DO - https://doi.org/10.1016/j.matpr.2022.02.594 SN - 2214-7853 VL - 62 SP - 2462 EP - 2465 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-54507 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Hirschberger, Paul A1 - Bartholmai, Matthias ED - Zemčík, R. ED - Krystek, J. T1 - Influence of rotor downwash on vertically displaced nanobots in flight JF - Materials Today: Proceedings N2 - One challenge associated with navigating a nano aerial robot swarm indoors in unstructured environments is, i.a., the limited air space. To avoid an over-regulation of the available indoor air space (e.g., prohibit copters to fly above each other), a safety region around each copter must be defined. In this paper, we investigate the impact of the downwash of a nano-drone on the stability of another nearby nano-drone. In the experiments, we found out that this downwash has a negative influence of a second nano-drone in a distance of around 1 m vertically and 0.2 m horizontally. Based on the obtained data, we developed a model describing the above-mentioned safety region to enable a safe operation of the swarm in these environments with fewer constraints. T2 - 36th Danubia-Adria Symposium on Advances in Experimental Mechanics CY - Pilsen, Czech Republic DA - 24.09.2019 KW - Mobile Robot Olfaction KW - Nano aerial robot KW - Swarm KW - Collision-free navigation KW - Safety region model PY - 2020 DO - https://doi.org/10.1016/j.matpr.2020.03.047 VL - 32 IS - 2 SP - 108 EP - 111 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-50673 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Ebert, S. A1 - Lazik, D. A1 - Bartholmai, Matthias ED - Nicoletto, G. ED - Dan Pastrama, S. ED - Emri, I. T1 - Inverse calibration routine for linear soil gas sensors JF - Materials Today: Proceedings N2 - Gas sensors in linear form based on the measuring principle of gas selective permeability through a membrane were developed and introduced for the detection and quantification of gas concentrations. A current field study focuses on measuring CO2 concentrations for a spatially distributed monitoring of subsurface CO2 gas storage sites in near real time. A 400 m² test site and a corresponding laboratory system were built up to characterize, validate, and optimize the sensor. A calibration routine was developed, which can be applied subsequently to underground installation. First measurement results indicate the potential of the method. T2 - 32nd Danubia Adria Symposium on Advances in Experimental Mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 KW - Linear sensor KW - Distributed sensor KW - Subsurface monitoring KW - Gas storage areas KW - Membrane-based gas sensing KW - Calibration PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S221478531600256X DO - https://doi.org/doi:10.1016/j.matpr.2016.03.051 SN - 2214-7853 VL - 3 IS - 4 SP - 1074 EP - 1078 PB - Elsevier Ltd. AN - OPUS4-35633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Bennetts, V.H. A1 - Lilienthal, A.J. A1 - Bartholmai, Matthias A1 - Schiller, J.H. T1 - Gas source localization with a micro-drone using bio-inspired and particle filter-based algorithms JF - Advanced robotics N2 - Gas source localization (GSL) with mobile robots is a challenging task due to the unpredictable nature of gas dispersion, the limitations of the currents sensing technologies, and the mobility constraints of ground-based robots. This work proposes an integral solution for the GSL task, including source declaration. We present a novel pseudo-gradient-based plume tracking algorithm and a particle filter-based source declaration approach, and apply it on a gas-sensitive micro-drone. We compare the performance of the proposed system in simulations and real-world experiments against two commonly used tracking algorithms adapted for aerial exploration missions. KW - Autonomous micro UAV KW - Chemical and wind sensing KW - Gas source localization KW - Particle filter PY - 2013 DO - https://doi.org/10.1080/01691864.2013.779052 SN - 0169-1864 SP - 725 EP - 738 PB - VNU Sciences Pr. CY - Utrecht AN - OPUS4-28010 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Bartholmai, Matthias T1 - Real-time wind estimation on a micro unmanned aerial vehicle using its inertial measurement unit JF - Sensors and actuators A: Physical N2 - This paper presents an approach for a quadrocoper-based micro unmanned aerial vehicle (UAV) that estimates the wind vector (speed and direction) in real-time based on measurement data of its on-board sensors only. This method does not need any additional airspeed sensor or dedicated anemometer, and thus the micro UAV's valuable payload remains free for other sensors. Wind tunnel and field tests were used to evaluate the performance of the approach. In order to quantify its accuracy, experiments are presented where data was collected with an anemometer placed in an open field with the micro UAV in flight following a predefined trajectory around the anemometer and hovering at a defined position close to it. KW - Micro unmanned aerial vehicle (UAV) KW - Quadrocopter KW - Real-time KW - Inertial measurement unit (IMU) KW - Airspeed calibration KW - Wind estimation (speed and direction) PY - 2015 DO - https://doi.org/10.1016/j.sna.2015.09.036 SN - 0924-4247 VL - 235 SP - 300 EP - 310 PB - Elsevier Science CY - Amsterdam [u.a.] AN - OPUS4-34737 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neumann, Patrick P. A1 - Asadi, S. A1 - Lilienthal, A.J. A1 - Bartholmai, Matthias A1 - Schiller, J.H. T1 - Autonomous gas-sensitive microdrone - wind vector estimation and gas distribution mapping JF - IEEE Robotics and automation magazine N2 - This article presents the development and validation of an autonomous, gas sensitive microdrone that is capable of estimating the wind vector in real time using only the onboard control unit of the microdrone and performing gas distribution mapping (DM). Two different sampling approaches are suggested to address this problem. On the one hand, a predefined trajectory is used to explore the target area with the microdrone in a real-world gas DM experiment. As an alternative sampling approach, we introduce an adaptive strategy that suggests next sampling points based on an artificial potential field (APF). Initial results in real-world experiments demonstrate the capability of the proposed adaptive sampling strategy for gas DM and its use for gas source localization. KW - Anemometric sensor KW - Autonomous micro UAV KW - Chemical sensing KW - Gas distribution modelling KW - Gas source localization KW - Gas sensors KW - Mobile sensing system KW - Quadrocopter KW - Sensor planning KW - Artificial potential field PY - 2012 DO - https://doi.org/10.1109/MRA.2012.2184671 SN - 1070-9932 VL - 19 IS - 1 SP - 50 EP - 61 PB - IEEE CY - New York, NY, USA AN - OPUS4-25773 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -