1,720,960 research outputs found
Laser Line Triangulation Sensors for Geometry Measurement in Hot Forging Industry: Design, Prototype and Inline Integration
No full textQuesta ricerca presenta un sistema di ispezione non distruttiva (NDI) basato sulla tecnologia di triangolazione laser (LLT) per la misurazione geometrica, applicato al controllo qualità in linea nell’industria della forgiatura a caldo per Zero-Defect-Manufacturing nell'ambito del progetto HE openZDM.
L'applicazione è sfidante poiché i sensori ottici devono essere implementati in condizioni industriali ostili e coprire un ampio campo di misura per misurare la rettilineità di barre di acciaio lunghe fino a 1 m, che vengono lavorate per forgiare sospensioni meccaniche. Visti i limiti delle soluzioni disponibili in commercio, questa ricerca presenta il prototipo di due repliche di sensori LLT ad alta risoluzione per un ampio campo di misura.
Uno dei sensori progettati è particolarmente innovativo in quanto consente l'ispezione di prodotti ad alta temperatura, fino a 1200 °C, che risulta critica visto il basso contrasto della linea laser rispetto alla superficie della barra calda incandescente. Questa ricerca propone soluzioni per migliorare il rapporto segnale/rumore, ottimizzando le prestazioni del sensore sia dal punto di vista hardware che software.
La tesi copre tutte le fasi dello sviluppo dei prototipi LLT, dal disegno CAD iniziale, all'assemblaggio, la calibrazione e infine l'installazione in linea di produzione. L'applicazione è completamente automatica, garantendo un'ispezione del 100% dei prodotti. Gli NDI sono completamente integrati nell’infrastruttura digitale dell’industria e comunicano tramite MQTT con il PLC e la piattaforma openZDM per la condivisione dei dati.
Pertanto, lo sviluppo del prototipo LLT si è rivelato un successo, poiché i sistemi sono pienamente operativi e integrati in linea di produzione, resistendo a condizioni ambientali difficili per più di un anno di installazione permanente e mantenendo al tempo stesso prestazioni stabili come è stato confermato dai risultati della Measurement System Analysis.This research presents a Non-Destructive-Inspection (NDI) system based on Laser Line Triangulation technology (LLT) for geometry measurement applied to inline quality control of a hot forging industrial use case for Zero-Defect-Manufacturing within the HE project openZDM.
The application proves challenging as the optical sensors have to be implemented in harsh industrial conditions while covering a wide measurement range, as they have to measure the straightness of steel bars, up to 1 m long, which are processed to form trailing arms. Addressing the limitations of the commercially available solutions, this research presents the prototype of two replicas of high-resolution LLT sensors for wide measurement range.
One of the LLT sensors designed is peculiarly innovative as it allows inspection on high-temperature products, up to 1200 °C which is critical given the low contrast of the laser line with respect to the glowing surface of the hot incandescent bar. This research proposes solutions to improve SNR (Signal to Noise Ratio), optimizing the sensor performances both hardware and software side.
This dissertation covers all the steps of the design and development of the LLT sensors prototype, from the initial CAD drawing, assembly, calibration and finally inline installation in production line. The application is fully automatic with 100% product inspection in less than 800 ms per product. The NDIs are fully integrated to the factory digital infrastructure, communicating through MQTT with the production line PLC and the openZDM platform for data sharing and error management.
Thus, the LLTs prototype development proves successful as the systems are fully operative and integrated in production line, withstanding harsh environmental conditions for more than one year of permanent inline installation, while maintaining stable performance as it has been confirmed by results of the Measurement System Analysis
A Jury Test Methodology for the Assessment of User Rifle Trigger Tactile Preference
Full text linkThis paper presents a methodology to evaluate the preference of the user in relation to the trigger of a rifle. The selected approach is based on a Jury Test methodology which is a well know assessment method used in several fields, such as the subjective perception of acoustic noise or sound evaluation. In this case, the subjective test is applied to the tactile perception of the user to the stimuli of the rifle trigger, thus exploiting the possible means of interaction the human has with the object of interest. This approach is really important to define a complete user experience, helping to reach an innovative vision in the design and development of the product.As the Jury Test collects subjective preferences given by the users, a methodology is presented to correlate objective indices to these subjective preferences. The correlation is performed considering different parameters of the rifle trigger, previously measured with a specific experimental campaign conducted on real rifles, using an elasticometer.A correlation analysis is presented to find the optimal values of the objective metrics in order to maximise the subjective preference. In particular the highest values of the preferences towards the rifle trigger are correlated to the parameter of the trigger force and displacement. Best values have been found to be low force applied to the trigger and low trigger displacement. This method proves therefore to be efficient in correlating the parameters of this application case providing quantifiable feedback on the product in the context of a User-Centred Design
Laser line triangulation measurement on incandescent steel objects: methodologies to improve optical signal to noise ratio
Full text linkIntegrating optical sensors into harsh industrial environments poses challenges and limits to the application. This paper discusses the implementation of a LLT (Laser Line Triangulation) sensor in a steel industry use case, designed to measure the straightness of steel bars at very high temperatures, up to 1000-1200 °C. Due to the bar incandescence it is challenging to use the optical instrument, as Signal to Noise Ratio (SNR) of the laser line projected onto the inspected object is lower than 2 dB. Both hardware and software solutions are investigated, in particular the choice of a very narrowband filter is selected to remove quite all the other spectral content coming from the bar irradiance. Even though this solution enhances SNR, the narrow band filter blocks the laser irradiance at the edges of the field of view: a reference ruler measured at ambient temperature has shown that 40.3 % of the length of the bar is not detected with respect to the measurement without the narrow band filter. To cope with this issue, a software solution is implemented which consists in the preprocessing of the image with a Region of Interest (ROI) around the laser line. This solution imposes the constraint of repeatable product positioning which has to be assured by the robot which picks up the product for the measurement. Applying the ROI, the Laser Line Extraction (LLE) algorithm detects clearly the laser line, with outliers reduction of 97.5 % with respect to the case without ROI introduction
Laser Line Triangulation Sensor with Wide Measurement Range: a Steel Industry Use Case
No full textLaser line triangulation is a key measurement technology that can be applied in quality control processes to inspect product geometry without contact. This paper presents the design of a Laser Line Triangulation (LLT) sensor developed in the context of the Horizon Europe (HE) project openZDM and tested inline in a steel industry use case.The LLT sensor has been developed focusing on two main target objectives: wide measurement range along transversal (X) and axial (Z) directions and small resolution along the Z axis. These have been achieved thanks to the optimization of the design parameters of the system which has been implemented with a triangulation angle of 45° reaching over a stand-off distance of 1000 mm and a 1000 mm camera-laser distance. The overall measurement range results in a transversal Field-OfView (X-FOV) from 800 mm to 2000 mm and a minimum Z distance of 630 mm in the near field up to 1580 mm in the far field.The resolution along the Z axis has been enhanced thanks to the introduction of subpixel accuracy reaching 0.026 mm at the stand-off distance which is 1000 mm. In this paper, these values are compared to other Laser Line Triangulation sensors available on the market showing that the system developed by UNIVPM is innovative.The Laser Line Triangulation sensor has been also tested inline and this paper presents some results of the laser profiles acquired on a steel bar held by a robot. These laser profiles are then processed in order to detect geometric defects, in particular the non-straightness of the bar, using an algorithm properly developed for the use case. From the results of these feasibility tests, the application has proven effective and opens the path to a full-inline installation, in order to measure non-straightness on 100% of the products.Laser line triangulation is a key measurement technology that can be applied in quality control processes to inspect product geometry without contact. This paper presents the design of a Laser Line Triangulation (LLT) sensor developed in the context of the Horizon Europe (HE) project openZDM and tested inline in a steel industry use case.The LLT sensor has been developed focusing on two main target objectives: wide measurement range along transversal (X) and axial (Z) directions and small resolution along the Z axis. These have been achieved thanks to the optimization of the design parameters of the system which has been implemented with a triangulation angle of 45° reaching over a stand-off distance of 1000 mm and a 1000 mm camera-laser distance. The overall measurement range results in a transversal Field-OfView (X-FOV) from 800 mm to 2000 mm and a minimum Z distance of 630 mm in the near field up to 1580 mm in the far field.The resolution along the Z axis has been enhanced thanks to the introduction of subpixel accuracy reaching 0.026 mm at the stand-off distance which is 1000 mm. In this paper, these values are compared to other Laser Line Triangulation sensors available on the market showing that the system developed by UNIVPM is innovative.The Laser Line Triangulation sensor has been also tested inline and this paper presents some results of the laser profiles acquired on a steel bar held by a robot. These laser profiles are then processed in order to detect geometric defects, in particular the non-straightness of the bar, using an algorithm properly developed for the use case. From the results of these feasibility tests, the application has proven effective and opens the path to a full-inline installation, in order to measure non-straightness on 100% of the products
Induction Cooker Acoustic Assessment: Sound Quality Analysis and Correlation with Jury Test Results
No full textLiving environment standards are raising addressing different aspects of human life such as thermal but also acoustic comfort. This paper focuses on the domestic environment of the kitchen presenting an acoustic assessment of a common household appliance which is the induction cooker. The induction cooker acoustic analysis is presented reporting measured signals acquired in operative conditions. Results also on sound quality are presented showing that values of Loudness, Sharpness and Open Articulation Index (OAI) are not critical. For example, the OAI values are all over 100% considering the selected signals. However, Sound Quality (SQ) metrics are not enough to evaluate the sound perception of the user towards the product. That is why it is important to target them towards the user needs thanks to a Jury Test (JT). The jury test, which has a total duration of about 4 minutes, has been presented to the jury in the A-B Comparison type presenting four sounds for a 10 s duration each. A demographic analysis of the jury is also carried out in order to better correlate the user preference considering the Consistency-Concordance values. The results present the correlation between Subjective Preference Index (SPI) values and the objective sound quality metrics, in order to tune a sound quality model for SPI prediction. Metrics of Loudness and Sharpness have proven the most representative of the use case. The jury test presented is therefore crucial to better relate the objective metrics in order to create a user-centered sound quality analysis of the product
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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