Fusion of photogrammetry and coherence scanning interferometry data for all-optical coordinate measurement

Multisensor data fusion is an approach to enlarge the potential applicability of measuring techniques and improve accuracy, taking advantage of the strengths of different techniques. In this work, we present a new method for the fusion of photogrammetry and coherence scanning interferometry (CSI) data. This method allows the photogrammetry data to be accurately scaled with reference to the CSI data, and in turn the exact locations of multiple CSI measurements can be determined in the coordinate system defined by photogrammetry. The culmination of this work is to allow for high-accuracy three-dimensional optical coordinate measurement and surface topography measurement simultaneously

Enhancing optical measuring systems for manufacturing process control

Modern industries are stressed by the market for a crazy and continuous reduction of time-to-market and an increase of required quality of final products. Manufacturing should evolve in order to satisfy market, by increasing the process complexity and fighting against requirements (in terms of batch sizes and tolerances). Production should be fast and accurate and this implies that measuring systems have to be faster, more flexible and possibly in-line, in order to continuously adjust the process. Optical metrology seems to be the perfect solution for this challenging context. However, optical metrology is characterized by binding physical limitations that reduce accuracy and sometimes applicability. Nevertheless, the exponential increase of computational power helps the evolution and optimization of optical measuring systems by permitting real time corrections and fast post-process. The aim of this work is the development of different correction and numerical methods to enhance optical measuring system capabilities. Confocal microscopy, optical CMM (coordinate measuring systems) and X-ray computed tomography are analysed in different types of applications, ensuring a reduction of measuring process variability and increasing measurement accuracy. Algorithms developed specifically for quantification and minimization of influencing factors are presented and implemented for real time correction and control of manufacturing process. Void pixels in confocal microscopy are studied and managed, thus reducing variability of surface roughness parameters and increasing capabilities of measuring instrument for micro-milling process control. Optical systems are analysed for thread measurements proposing a correction method for inline, fast and reliable evaluation of threads geometry. Finally, surface roughness is taken into account for correction of computed tomography dimensional measurements. Different technologies applied in different fields are joined by the common need of correction for enhancing measuring capabilities.L’industria moderna è messa sotto pressione dalla costante riduzione del tempo disponibile per l’immissione sul mercato dei prodotti e dall’incessante aumento dei requisiti richiesti sui prodotti finali. I sistemi di produzione devono dunque evolversi per poter soddisfare il mercato, incrementando la complessità dei processi e confrontandosi continuamente con le richieste (in termini sia di produttività sia di tolleranze). La produzione deve quindi essere veloce e allo stesso tempo accurata: questo implica che i sistemi di misura, per poter controllare continuamente il processo, debbano essere a loro volta veloci, flessibili e possibilmente in linea. Per poter essere competitivi in questo contesto appare evidente che i sistemi ottici siano un’ottima soluzione. Tuttavia, la metrologia ottica è vincolata da alcune limitazioni fisiche insite nella tecnologia che ne inficiano l’accuratezza e talvolta l’applicabilità. Ciononostante, l’aumento esponenziale della potenza di calcolo ha aiutato notevolmente lo sviluppo e l’ottimizzazione dei sistemi di misura ottici, permettendo l’applicazione delle correzioni in tempo reale e accelerando il processo di elaborazione dei dati raccolti. L’obiettivo di questo lavoro è lo sviluppo di diverse correzioni e metodi numerici che assicurino un miglioramento delle caratteristiche di alcuni sistemi di misura ottici. Microscopia confocale, macchine di misura a coordinate ottiche e tomografia computerizzata ai raggi X vengono analizzate in diversi campi di applicazione, assicurando una riduzione della variabilità dei processi produttivi attraverso un miglioramento dell’accuratezza della misura. Gli algoritmi, sviluppati specificatamente per quantificare e minimizzare i fattori di influenza, sono presentati e implementati in modo da permettere una correzione in tempo reale delle misure e un maggior controllo del processo di produzione. I void pixels nella microscopia confocale vengono analizzati e controllati al fine di ridurre la variabilità dei parametri di finitura superficiale e aumentare le capacità e l’applicabilità di tale tecnologia per il controllo del processo di micro-fresatura. I sistemi ottici vengono analizzati anche per la misura delle filettature, proponendo un metodo di correzione flessibile, affidabile e applicabile direttamente sulla linea di produzione. Il metodo studiato permette di ottenere i parametri geometrici che descrivono le filettature direttamente dalla proiezione d’ombra senza la necessità di alcun input da parte dell’operatore. Infine, la rugosità superficiale viene considerata e analizzata per ridurre la variabilità delle misure geometriche nella tomografia computerizzata. Tecnologie molto diverse applicate in campi molto diversi sono qui legate dalla comune necessità di migliorare le capacità e le potenzialità dei sistemi di misura

Development of a method to increase the accuracy of a straightness measurement system for long workpieces

This thesis proposes a new method to extend the measuring range of the Raytec Gepard system for straighness measurements. The system accuracy on long distances without any correction is not compatible with the industrial and operative requests. The idea that is developed in this work is to obtain the straightness measurement of long workpieces as combination of different an shorter steps. Problems and errors related with the application of this method are analyzed and solved.reservedEmbargo permanente per motivi di segretezza e/o di proprietà dei risultati e informazioni di enti esterni o aziende private che hanno partecipato alla realizzazione del lavoro di ricerca relativo alla tes

Enhancing optical measuring systems for manufacturing process control

Modern industries are stressed by the market for a crazy and continuous reduction of time-to-market and an increase of required quality of final products. Manufacturing should evolve in order to satisfy market, by increasing the process complexity and fighting against requirements (in terms of batch sizes and tolerances). Production should be fast and accurate and this implies that measuring systems have to be faster, more flexible and possibly in-line, in order to continuously adjust the process. Optical metrology seems to be the perfect solution for this challenging context. However, optical metrology is characterized by binding physical limitations that reduce accuracy and sometimes applicability. Nevertheless, the exponential increase of computational power helps the evolution and optimization of optical measuring systems by permitting real time corrections and fast post-process. The aim of this work is the development of different correction and numerical methods to enhance optical measuring system capabilities. Confocal microscopy, optical CMM (coordinate measuring systems) and X-ray computed tomography are analysed in different types of applications, ensuring a reduction of measuring process variability and increasing measurement accuracy. Algorithms developed specifically for quantification and minimization of influencing factors are presented and implemented for real time correction and control of manufacturing process. Void pixels in confocal microscopy are studied and managed, thus reducing variability of surface roughness parameters and increasing capabilities of measuring instrument for micro-milling process control. Optical systems are analysed for thread measurements proposing a correction method for inline, fast and reliable evaluation of threads geometry. Finally, surface roughness is taken into account for correction of computed tomography dimensional measurements. Different technologies applied in different fields are joined by the common need of correction for enhancing measuring capabilities

Development of a method to increase the accuracy of a straightness measurement system for long workpieces

This thesis proposes a new method to extend the measuring range of the Raytec Gepard system for straighness measurements. The system accuracy on long distances without any correction is not compatible with the industrial and operative requests. The idea that is developed in this work is to obtain the straightness measurement of long workpieces as combination of different an shorter steps. Problems and errors related with the application of this method are analyzed and solved

Effect of void pixels on the quantification of surface topography parameters

In the last decades the measurement of surface topographies was further developed using the capabilities of 3D optical profilers based on different measuring principles. These instruments have significant advantages over contact stylus measuring instruments but also some limitations. One limitation is depending from the interaction of the surface with the numerical aperture of the objective. Because of the surface slope, some parts of the surface are not correctly detected by the instrument, resulting on void pixels i.e. missing information on the measured topography. Data generated using fitting algorithms can be used to reconstruct the surface and replace the missing data, and the way this operation is performed affects the evaluation of surface parameters. As an alternative, the calculation of parameters may be performed on non-reconstructed datasets. In this work, the effect of void pixels on the determination of 3D parameters on different manufactured surfaces has been investigated using computer simulation starting from actual measurement data. Both randomly distributed and slope-dependent void pixels are considered. A sensitivity analysis with different distributions of void pixels as well as the effect of increasing slope are also presented

A methodology for 3D geometrical characterisation of microfluidic channels using optical microscopy

In manufactured microfluidic channels, geometrical imperfections resulting from the manufacturing process are challenging in terms of reliability and functionality of the microfluidic device. In this work, a methodology for the geometrical and dimensional characterization of microfluidic channels using quantitative 3D optical microscopy is proposed. The methodology is based on a holistic approach including the identification of functionally relevant geometrical features and critical dimensions at design stage, as well as the related verification process at the manufacturing stage. At design stage, the critical geometrical characteristics are identified on the basis of their relation with the performance of the microfluidic device. Verification is based on a novel methodology in which measurement results collected by a surface topography measuring instrument are processed on the basis of concepts and procedures commonly applied to data generated by a coordinate measuring system

Metis naviga verso lo scafo riciclabile!

Il gruppo di studenti universitari M\ue8tisVelaUnipd (www.metisvela.dii.unipd.it), nato nel 2008, si inserisce all\u2019interno del progetto 1001VelaCup (www.1001velacup.eu), che prevede la progettazione, realizzazione e conduzione di scafi a vela da regata per un confronto tra vari atenei italiani ed europei sulla base di un regolamento che impone la lunghezza fuori tutto (4.6 m), la superficie velica complessiva (33 m2) e i materiali utilizzabili, lasciando liberi gli altri parametri di progetto, e favorendo quindi la ricerca di nuove soluzioni creative. La regola principale e pi\uf9 restrittiva riguarda i materiali: il 70% in peso dello scafo deve avere origine animale o vegetale. Le prime due imbarcazionidel gruppo padovano, Argo (2008) e Aura (2009), sono state costruite in legno mentre le due successive, Aret\ue9 (2012) e Ate (2016), sono prodotte con un composito con fibra di lino e core in balsa