M. Mathis, Dennis Vollberg, M. Langosch, Dirk Göttel, A. Lellig, G. Schultes
Abstract. An important property of high-precision mechanical sensors such as force transducers or torque sensors is the so-called creep error. It is defined as the signal deviation over time at a constant load. Since this signal deviation results in a reduced accuracy of the sensor, it is beneficial to minimize the creep error. Many of these sensors consist of a metallic spring element and strain gauges. In order to realize a sensor with a creep error of almost zero, it is necessary to compensate for the creep behavior of the metallic spring element. This can be achieved by creep adjustment of the used strain gauges. Unlike standard metal foil strain gauges with a gauge factor of 2, a type of strain gauges based on sputter-deposited NiCr -carbon thin films on polymer substrates offers the advantage of an improved gauge factor of about 10. However, for this type of strain gauge, creep adjustment by customary methods is not possible. In order to remedy this disadvantage, a thorough creep analysis is carried out. Five major influences on the creep error of force transducers equipped with NiCr -carbon thin-film strain gauges are examined, namely, the material creep of the metallic spring element (1), the creep (relaxation) of the polymer substrate (2), the composition of the thin film (3), the strain transfer to the thin film (4), and the kind of strain field on the surface of the transducer (5). Consequently, we present two applicable methods for creep adjustment of NiCr -carbon thin- film strain gauges. The first method addresses the intrinsic creep behavior of the thin film by a modification of the film composition. With increasing Cr content (at the expense of Ni, the intrinsic negative creep error can be shifted towards zero. The second method is not based on the thin film itself but rather on a modification of the strain transfer from the polyimide carrier to the thin film. This is achieved by controlled cutting of well-defined deep trenches into the polymer substrate via a picosecond laser.
{"title":"Creep adjustment of strain gauges based on granular NiCr-carbon thin films","authors":"M. Mathis, Dennis Vollberg, M. Langosch, Dirk Göttel, A. Lellig, G. Schultes","doi":"10.5194/JSSS-10-53-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-53-2021","url":null,"abstract":"Abstract. An important property of high-precision mechanical sensors such as force transducers or torque sensors is the so-called creep error. It is defined as the signal deviation over time at a constant load. Since this signal deviation results in a reduced accuracy of the sensor, it is beneficial to minimize the creep error. Many of these sensors consist of a metallic spring element and strain gauges. In order to realize a sensor with a creep error of almost zero, it is necessary to compensate for the creep behavior of the metallic spring element. This can be achieved by creep adjustment of the used strain gauges. Unlike standard metal foil strain gauges with a gauge factor of 2, a type of strain gauges based on sputter-deposited NiCr -carbon thin films on polymer substrates offers the advantage of an improved gauge factor of about 10. However, for this type of strain gauge, creep adjustment by customary methods is not possible. In order to remedy this disadvantage, a thorough creep analysis is carried out. Five major influences on the creep error of force transducers equipped with NiCr -carbon thin-film strain gauges are examined, namely, the material creep of the metallic spring element (1), the creep (relaxation) of the polymer substrate (2), the composition of the thin film (3), the strain transfer to the thin film (4), and the kind of strain field on the surface of the transducer (5). Consequently, we present two applicable methods for creep adjustment of NiCr -carbon thin- film strain gauges. The first method addresses the intrinsic creep behavior of the thin film by a modification of the film composition. With increasing Cr content (at the expense of Ni, the intrinsic negative creep error can be shifted towards zero. The second method is not based on the thin film itself but rather on a modification of the strain transfer from the polyimide carrier to the thin film. This is achieved by controlled cutting of well-defined deep trenches into the polymer substrate via a picosecond laser.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"10 1","pages":"53-61"},"PeriodicalIF":1.0,"publicationDate":"2021-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47332322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. Yurchenko, H. Pernau, L. Engel, B. Bierer, M. Jägle, J. Wöllenstein
Abstract. Differential thermal analysis (DTA) was used to examine the effect of the particle size and morphology of cobalt (III/IV) oxide ( Co3O4 ) on its thermal response under exposure to methane (1 vol % in dry synthetic air), which is a relevant gas for the detection of combustible gases. The DTA response results from the catalytic oxidation of methane, and its characteristics should correlate with the pellistor response. Co3O4 samples differing in particle size and morphology were produced by ball milling (top-down technique) or were synthesized from precursor molecules by precipitation (bottom-up technique). The investigations carried out in dry air and a temperature range between 250 and 450 ∘ C reveal that both particle size and particle shape have a considerable effect on thermal response, since the resulting layer structures and the associated surface area available for gas interaction differ. The Co3O4 catalyst, with small particles and an irregular shape, exhibits significantly higher response than milled Co3O4 samples. Comparison of DTA with the mass spectroscopy signal of CO2 evolved by the reaction verified a certain analogy between DTA measurements and the response produced by a pellistor.
{"title":"Impact of particle size and morphology of cobalt oxide on the thermal response to methane examined by thermal analysis","authors":"O. Yurchenko, H. Pernau, L. Engel, B. Bierer, M. Jägle, J. Wöllenstein","doi":"10.5194/JSSS-10-37-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-37-2021","url":null,"abstract":"Abstract. Differential thermal analysis (DTA) was used to examine the effect of the particle size and morphology of cobalt (III/IV) oxide ( Co3O4 ) on its thermal response under exposure to methane (1 vol % in dry synthetic air), which is a relevant gas for the detection of combustible gases. The DTA response results from the catalytic oxidation of methane, and its characteristics should correlate with the pellistor response. Co3O4 samples differing in particle size and morphology were produced by ball milling (top-down technique) or were synthesized from precursor molecules by precipitation (bottom-up technique). The investigations carried out in dry air and a temperature range between 250 and 450 ∘ C reveal that both particle size and particle shape have a considerable effect on thermal response, since the resulting layer structures and the associated surface area available for gas interaction differ. The Co3O4 catalyst, with small particles and an irregular shape, exhibits significantly higher response than milled Co3O4 samples. Comparison of DTA with the mass spectroscopy signal of CO2 evolved by the reaction verified a certain analogy between DTA measurements and the response produced by a pellistor.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"10 1","pages":"37-42"},"PeriodicalIF":1.0,"publicationDate":"2021-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48801177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Bifano, A. Fischerauer, A. Liedtke, G. Fischerauer
Abstract. The global economy consumes an estimated 4×1010 t of sand per year, with only 2×1010 t of sand being reproduced by natural sedimentation (Gotze and Gobbels, 2017; Peduzzi, 2014). Among other things, sand is also used as a basic material for the production of molds and cores in the foundry industry. The consumption and the economic as well as ecological savings' potential in this area of application can be appreciated by way of an example: the environmental certificate of a single, albeit big German foundry (5160 employees) can be consulted, which states that 39 820 t of sand for casting molds had to be purchased in 2017 (Denes, 2018). In order to avoid having to dispose of the used sand in landfills and to reduce the use of new sand, it is therefore advantageous to renew the used sand in a so-called regeneration process and reuse it as a substitute for new sand in the production of molds and cores. It would be very advantageous if the condition of molding materials (sand–binder systems) in regenerator units could be monitored in real time because of the economic and ecological advantages of a monitored and optimized regeneration process. This work presents the results of investigations in this direction. The objects of investigation in this work are typical molding materials in the foundry industry, e.g., quartz sand, chromite sand, and bentonite as a binder, which are measured impedimetrically with the help of a plate capacitor measuring cell which is connected to an LCR meter (Agilent E4980A). The impedance of the filled capacitor is measured in a frequency range from 1.2 kHz to 1 MHz, containing 123 frequency points. The aim of this research is to work out if the mentioned substances can be measured with the presented measuring method and classified on the basis of impedance characteristics and thus whether impedance spectroscopy can be considered for process monitoring in the molding industry. It is shown that the condition monitoring can possibly be based on impedance spectroscopy because the resulting curves are characteristic of the material used. New and used sands as well as two-component mixtures of sands and binders showed a systematic behavior, which allows the sand or the composition of the mixture to be identified (classified) in the future. The examination of the scatter of the measurement results shows that the impedance data obtained with this method can be measured reproducibly. A descriptive model for multi-component systems is developed in order to be able to interpret the impedance scatter results and their representation in Nyquist plots. From this model, the filling density of the measurement cell and the density of conduction paths can be extracted as essential influence quantities.
{"title":"Characterization of sand and sand–binder systems from the foundry industry with electrical impedance spectroscopy","authors":"L. Bifano, A. Fischerauer, A. Liedtke, G. Fischerauer","doi":"10.5194/JSSS-10-43-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-43-2021","url":null,"abstract":"Abstract. The global economy consumes an estimated 4×1010 t of sand\u0000per year, with only 2×1010 t of sand being reproduced by natural\u0000sedimentation (Gotze and Gobbels, 2017; Peduzzi, 2014). Among other things, sand\u0000is also used as a basic material for the production of molds and cores in\u0000the foundry industry. The consumption and the economic as well as ecological\u0000savings' potential in this area of application can be appreciated by way of\u0000an example: the environmental certificate of a single, albeit big German\u0000foundry (5160 employees) can be consulted, which states that 39 820 t of\u0000sand for casting molds had to be purchased in 2017 (Denes, 2018). In order\u0000to avoid having to dispose of the used sand in landfills and to reduce the use of new sand,\u0000it is therefore advantageous to renew the used sand in a so-called\u0000regeneration process and reuse it as a substitute for new sand in the\u0000production of molds and cores. It would be very advantageous if the\u0000condition of molding materials (sand–binder systems) in regenerator units\u0000could be monitored in real time because of the economic and ecological\u0000advantages of a monitored and optimized regeneration process. This work\u0000presents the results of investigations in this direction. The objects of\u0000investigation in this work are typical molding materials in the foundry\u0000industry, e.g., quartz sand, chromite sand, and bentonite as a binder, which\u0000are measured impedimetrically with the help of a plate capacitor measuring\u0000cell which is connected to an LCR meter (Agilent E4980A). The impedance of\u0000the filled capacitor is measured in a frequency range from 1.2 kHz to 1 MHz,\u0000containing 123 frequency points. The aim of this research is to work out if\u0000the mentioned substances can be measured with the presented measuring method\u0000and classified on the basis of impedance characteristics and thus whether impedance\u0000spectroscopy can be considered for process monitoring in the molding\u0000industry. It is shown that the condition monitoring can possibly be based on\u0000impedance spectroscopy because the resulting curves are characteristic of\u0000the material used. New and used sands as well as two-component mixtures of\u0000sands and binders showed a systematic behavior, which allows the sand or the\u0000composition of the mixture to be identified (classified) in the future. The\u0000examination of the scatter of the measurement results shows that the\u0000impedance data obtained with this method can be measured reproducibly. A\u0000descriptive model for multi-component systems is developed in order to be\u0000able to interpret the impedance scatter results and their representation in\u0000Nyquist plots. From this model, the filling density of the measurement cell\u0000and the density of conduction paths can be extracted as essential influence\u0000quantities.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"10 1","pages":"43-51"},"PeriodicalIF":1.0,"publicationDate":"2021-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48376036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Strahl, J. Herbst, Eric Maier, S. Rademacher, C. Weber, H. Pernau, A. Lambrecht, J. Wöllenstein
Abstract. The measurement of low methane ( CH4 ) concentrations is a key objective for safety of industrial and public infrastructures and in environmental research. Laser spectroscopy is best suited for this purpose because it offers high sensitivity, selectivity, dynamic range, and a fast measurement rate. The physical basis of this technique is infrared absorption of molecular gases. Two detection schemes – direct absorption spectroscopy (DAS) and photoacoustic spectroscopy (PAS) – are compared at three wavelength regions in the near-infrared (NIR), mid-wavelength (MWIR), and long-wavelength (LWIR) infrared ranges. For each spectral range a suitable semiconductor laser is selected and used for both detection techniques: a diode laser (DL), an interband cascade laser (ICL), and a quantum cascade laser (QCL) for NIR, MWIR and LWIR, respectively. For DAS short absorption path lengths comparable to the cell dimensions of the photoacoustic cell for PAS are employed. We show that for DAS the lowest detection limit can be achieved in the MWIR range with noise-equivalent concentrations (NECs) below 10 ppb. Using PAS, lower detection limits and higher system stabilities can be reached compared to DAS, especially for long integration times. The lowest detection limit for PAS is obtained in the LWIR with a NEC of 7 ppb. The different DAS and PAS configurations are discussed with respect to potential applications.
{"title":"Comparison of laser-based photoacoustic and optical detection of methane","authors":"T. Strahl, J. Herbst, Eric Maier, S. Rademacher, C. Weber, H. Pernau, A. Lambrecht, J. Wöllenstein","doi":"10.5194/JSSS-10-25-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-25-2021","url":null,"abstract":"Abstract. The measurement of low methane ( CH4 ) concentrations is a key objective for safety of industrial and public infrastructures and in environmental research. Laser spectroscopy is best suited for this purpose because it offers high sensitivity, selectivity, dynamic range, and a fast measurement rate. The physical basis of this technique is infrared absorption of molecular gases. Two detection schemes – direct absorption spectroscopy (DAS) and photoacoustic spectroscopy (PAS) – are compared at three wavelength regions in the near-infrared (NIR), mid-wavelength (MWIR), and long-wavelength (LWIR) infrared ranges. For each spectral range a suitable semiconductor laser is selected and used for both detection techniques: a diode laser (DL), an interband cascade laser (ICL), and a quantum cascade laser (QCL) for NIR, MWIR and LWIR, respectively. For DAS short absorption path lengths comparable to the cell dimensions of the photoacoustic cell for PAS are employed. We show that for DAS the lowest detection limit can be achieved in the MWIR range with noise-equivalent concentrations (NECs) below 10 ppb. Using PAS, lower detection limits and higher system stabilities can be reached compared to DAS, especially for long integration times. The lowest detection limit for PAS is obtained in the LWIR with a NEC of 7 ppb. The different DAS and PAS configurations are discussed with respect to potential applications.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"10 1","pages":"25-35"},"PeriodicalIF":1.0,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45573839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Nitsche, M. Franke, N. Haverkamp, D. Heißelmann
Abstract. The estimation of the six-degree-of-freedom position and orientation of an end effector is of high interest in industrial robotics. High precision and data rates are important requirements when choosing an adequate measurement system. In this work, a six-degree-of-freedom pose estimation setup based on laser multilateration is described together with the measurement principle and self-calibration strategies used in this setup. In an experimental setup, data rates of 200 Hz are achieved. During movement, deviations from a reference coordinate measuring machine of 20 µm are observed. During standstill, the deviations are reduced to 5 µm .
{"title":"Six-degree-of-freedom pose estimation with µm/µrad accuracy based on laser multilateration","authors":"J. Nitsche, M. Franke, N. Haverkamp, D. Heißelmann","doi":"10.5194/JSSS-10-19-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-19-2021","url":null,"abstract":"Abstract. The estimation of the six-degree-of-freedom position and orientation of an end effector is of high interest in industrial robotics. High precision and data rates are important requirements when choosing an adequate measurement system. In this work, a six-degree-of-freedom pose estimation setup based on laser multilateration is described together with the measurement principle and self-calibration strategies used in this setup. In an experimental setup, data rates of 200 Hz are achieved. During movement, deviations from a reference coordinate measuring machine of 20 µm are observed. During standstill, the deviations are reduced to 5 µm .","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"10 1","pages":"19-24"},"PeriodicalIF":1.0,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45609799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Laser materials processing of workpieces using ultra-short pulsed lasers can lead to unwanted X-ray emission. Their dose rate and spectral distribution have been precisely determined. The measurements were carried out using a thermoluminescence detector (TLD)-based spectrometer in which 30 TLD planes are arranged one behind the other, the first 10 layers made of polymethyl methacrylate, while the remaining 20 layers are interspaced by absorbers with, from the front to the back, increasing atomic charge and thickness. The penetration depth of the radiation into the spectrometer depends on its energy, so that the energy-resolved spectrum of the radiation can be calculated from the TLD dose values by means of mathematical methods (Bayesian deconvolution). The evaluation process also takes into account both the uncertainties of all input quantities and the possibility of adopting different models for the spectrum form. This allowed the resulting spectra to be associated with their realistic uncertainty. The measurements are traceable to the Systeme international d'unites (SI), i.e. the International System of Units. The results not only provide manufacturers and users of ultra-short pulsed lasers with important information on the design of the machines with regard to radiation protection, but were also included in the recently concluded legislative procedure in the field of radiation protection in Germany.
{"title":"Measurements at laser materials processing machines: spectrum deconvolution including uncertainties and model selection","authors":"R. Behrens, B. Pullner, M. Reginatto","doi":"10.5194/JSSS-10-13-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-13-2021","url":null,"abstract":"Abstract. Laser materials processing of workpieces using ultra-short pulsed lasers can lead to unwanted X-ray emission. Their dose rate and spectral distribution have been precisely determined. The measurements were\u0000carried out using a thermoluminescence detector (TLD)-based spectrometer in which 30 TLD planes are arranged one behind the other, the first 10 layers\u0000made of polymethyl methacrylate, while the remaining 20 layers are interspaced by absorbers with, from the front to the back, increasing atomic\u0000charge and thickness. The penetration depth of the radiation into the\u0000spectrometer depends on its energy, so that the energy-resolved spectrum of\u0000the radiation can be calculated from the TLD dose values by means of\u0000mathematical methods (Bayesian deconvolution). The evaluation process also\u0000takes into account both the uncertainties of all input quantities and the\u0000possibility of adopting different models for the spectrum form. This allowed\u0000the resulting spectra to be associated with their realistic uncertainty. The measurements are traceable to the Systeme international d'unites (SI), i.e. the International System of Units. The results not only provide manufacturers and users of ultra-short pulsed lasers with important information on the design of the machines with regard to radiation\u0000protection, but were also included in the recently concluded legislative procedure in the field of radiation protection in Germany.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"10 1","pages":"13-18"},"PeriodicalIF":1.0,"publicationDate":"2021-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47786655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Bernhardsgrütter, C. Hepp, M. Jägle, H. Pernau, K. Schmitt, J. Wöllenstein
Abstract. Because diesel combustion processes produce harmful detrimental nitrous oxides, the selective catalytic reduction, an after-treatment method using diesel exhaust fluid (AdBlue) to reduce these emissions, is an important part in the cycle of the combustion process. Therefore, it is crucial to continuously monitor the quality of the diesel exhaust fluid to secure the ideal selective catalytic reduction. This article presents a platinum thin-film sensor using the 3 ω method which is able to characterize the diesel exhaust fluid. By means of the 3 ω method, information about the concentration of urea in water can be extracted. In this investigation, a digital lock-in amplification technique is used to execute the measurements. The results show that this sensor can determine the urea content within 1 % by weight. Moreover, besides the analysis of the 3 ω signal, the 1 ω signal is analyzed in depth to receive additional information about the temperature. Because the same structure can measure multiple parameters, such as concentration, temperature, and flow, the sensor might be a good alternative to the state-of-the-art diesel exhaust fluid sensor.
{"title":"Inline quality monitoring of diesel exhaust fluid (AdBlue) by using the 3ω method","authors":"R. Bernhardsgrütter, C. Hepp, M. Jägle, H. Pernau, K. Schmitt, J. Wöllenstein","doi":"10.5194/JSSS-10-5-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-5-2021","url":null,"abstract":"Abstract. Because diesel combustion processes produce harmful detrimental nitrous oxides, the selective catalytic reduction, an after-treatment method using diesel exhaust fluid (AdBlue) to reduce these emissions, is an important part in the cycle of the combustion process. Therefore, it is crucial to continuously monitor the quality of the diesel exhaust fluid to secure the ideal selective catalytic reduction. This article presents a platinum thin-film sensor using the 3 ω method which is able to characterize the diesel exhaust fluid. By means of the 3 ω method, information about the concentration of urea in water can be extracted. In this investigation, a digital lock-in amplification technique is used to execute the measurements. The results show that this sensor can determine the urea content within 1 % by weight. Moreover, besides the analysis of the 3 ω signal, the 1 ω signal is analyzed in depth to receive additional information about the temperature. Because the same structure can measure multiple parameters, such as concentration, temperature, and flow, the sensor might be a good alternative to the state-of-the-art diesel exhaust fluid sensor.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"10 1","pages":"5-12"},"PeriodicalIF":1.0,"publicationDate":"2021-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48608944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Different options were discussed before reaching the final agreement on the new definitions of the SI units, effective from 20 May 2019, especially with regard to the kilogram, now defined in terms of the numerical value of the Planck constant ( h ). Replacing the artefact definition of the kilogram with a new one based on the mass of a particle, or the atomic mass constant ( mu ), would have been preferable for ease of understanding, among other reasons. In this paper we discuss some limitations of teaching to different audiences what a kilogram is in the redefined International System of Units (SI), including realizations of the new definition.
{"title":"Explaining to different audiences the new definition and experimental realizations of the kilogram","authors":"J. Valdés","doi":"10.5194/JSSS-10-1-2021","DOIUrl":"https://doi.org/10.5194/JSSS-10-1-2021","url":null,"abstract":"Abstract. Different options were discussed before reaching the final agreement on the new definitions of the SI units, effective from 20 May 2019, especially with regard to the kilogram, now defined in terms of the numerical value of the Planck constant ( h ). Replacing the artefact definition of the kilogram with a new one based on the mass of a particle, or the atomic mass constant ( mu ), would have been preferable for ease of understanding, among other reasons. In this paper we discuss some limitations of teaching to different audiences what a kilogram is in the redefined International System of Units (SI), including realizations of the new definition.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"10 1","pages":"1-4"},"PeriodicalIF":1.0,"publicationDate":"2021-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45987514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.5194/jsss-10-219-2021
Martin Lerchen, Jakob Hornung, Yu Zou, T. Hausotte
Abstract. Additive manufacturing technologies are further developing from prototype to serial production. This trend requires rising challenges to the process-accompanying quality assurance. Optical in situ quality control approaches show great potential to generate accurate measurement data, which are essential for feedback control. If a reliable referencing concept for the layer-by-layer measured data is guaranteed, contour information can be used during the manufacturing to correct occurring geometrical deviations. Within this scientific study, two methods of optical, referenced in situ control of lateral displacements of additive manufactured contours are presented. In the first approach the 2-D contour of the melting pool is analysed in relation to a position-stable reference system implemented in the powder bed. The second approach uses the translucent contour of deeper layers covered with powder as a reference. Within the image evaluation several pre-processing steps like calibration, undistortion, rectification, illumination correction and low-pass filtering are essential for reliable and correct geometric measurements. The following adapted contour detection and position determination of the referenced melting pool contours are based on an extended edge detection algorithm according to Canny (1986). With the evaluation of further manufacturing layers of already lowered powder bed levels, it is possible to specify the influence of powder application on geometrical displacements separately. This is done by a comparison of the position of the detected powder-covered melting pool contours with the previously applied melted region. Consequently a better understanding of lateral contour displacements within the additive manufacturing process is the goal, which is important for a process-accompanying correction of geometrical deviations.
{"title":"Methods and procedure of referenced in situ control of lateral contour displacements in additive manufacturing","authors":"Martin Lerchen, Jakob Hornung, Yu Zou, T. Hausotte","doi":"10.5194/jsss-10-219-2021","DOIUrl":"https://doi.org/10.5194/jsss-10-219-2021","url":null,"abstract":"Abstract. Additive manufacturing technologies are further developing from prototype to serial production. This trend requires rising challenges to the process-accompanying quality assurance. Optical in situ quality control approaches show great potential to generate accurate measurement data, which are essential for feedback control. If a reliable referencing concept for the layer-by-layer measured data is guaranteed, contour information can be used during the manufacturing to correct occurring geometrical deviations. Within this scientific study, two methods of optical, referenced in situ control of lateral displacements of additive manufactured contours are presented. In the first approach the 2-D contour of the melting pool is analysed in relation to a position-stable reference system implemented in the powder bed. The second approach uses the translucent contour of deeper layers covered with powder as a reference. Within the image evaluation several pre-processing steps like calibration, undistortion, rectification, illumination correction and low-pass filtering are essential for reliable and correct geometric measurements. The following adapted contour detection and position determination of the referenced melting pool contours are based on an extended edge detection algorithm according to Canny (1986). With the evaluation of further manufacturing layers of already lowered powder bed levels, it is possible to specify the influence of powder application on geometrical displacements separately. This is done by a comparison of the position of the detected powder-covered melting pool contours with the previously applied melted region. Consequently a better understanding of lateral contour displacements within the additive manufacturing process is the goal, which is important for a process-accompanying correction of geometrical deviations.","PeriodicalId":17167,"journal":{"name":"Journal of Sensors and Sensor Systems","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70626778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.5194/jsss-10-261-2021
T. Binkele, D. Hilbig, M. Essameldin, T. Henning, F. Fleischmann, W. Lang
Abstract. The applications of freeform surfaces in optical components and systems are increasing more and more. Therefore, appropriate measurement techniques are needed to measure these freeform surfaces for verification. This task is still a challenge for most measurement techniques. In this paper, we propose a measurement technique for optical and other specular freeform surfaces based on experimental ray tracing. This technique is able to measure form and mid-spatial-frequency deviations simultaneously. The focus will be set on the sensing technique and the measurement uncertainties in the setup. As the measurement technique is described, an estimation of the influence of different uncertainties based on simulations is given. The result from an experimental measurement is evaluated in relation to the influence of the uncertainties. A comparison measurement for evaluation is given.
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