Research team

Industrial Vision Lab (InViLab)

Expertise

Focus on industrial knowledge in: Advanced mechanical design and CAE Industrial 3D-vision technology Optimization techniques Op3Mech stands for Optical Metrology, 3D design and Mechanics. The UAntwerp Op3Mech research group couples state-of-the-art industrial knowledge in the key areas of advanced mechanical design and industrial 3D-vision technology. The Op3Mech team members also share important expertise with respect to Computer Aided Engineering including finite element methods and optimization techniques. The UA-Op3Mech research group couples state-of-the-art industrial knowledge in the key areas of advanced mechanical design and industrial 3D-vision technology. The Op3Mech team members also share important expertise with respect to Computer Aided Engineering including finite element methods and optimization techniques. With the recent advances in 3D-vision technology, a strong coupling is reached between optical measurement techniques, robust design methods and industrial production methods. Design, modeling and optimization of point clouds, response surfaces including 3D interpretation is the core research of the Op3Mech group. By means of scientific publications, initiation of doctoral research, participation in projects and consulting activities, the group aims to increase the expertise in the key domains but also wants to share the knowledge with small and bigger enterprises on a national but also international level.

Q-INSPEX: Quantitative industrial inspection through non-invasive imaging. 15/10/2020 - 31/12/2026

Abstract

Q-INSPEX aims at the development of novel imaging and image processing protocols to non-invasively and quantitatively inspect objects and subjects. Core imaging technologies herein are X-ray, (near)-infrared, and TeraHertz imaging. These technologies are largely complementary to each other and can be used in different set-ups as (i) an R&D tool to measure specific characteristics of materials (e.g. food structures or polymers), (ii) as a quality control procedure implemented within an industrial setting (i.e. compatible with processing speeds) or (iii) in-field inspections of crops and infrastructure (e.g. corrosion). Furthermore, they can be applied in a wide variety of domains: additive manufacturing, composites, art objects, textiles, archaeology, crops, food, etc.

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Optimized skin tissue identification by combined thermal and hyperspectral imaging methodology. 01/01/2020 - 31/12/2023

Abstract

The determination of local components in human skin from in-vivo measurements is crucial for medical applications, especially for aiding the diagnostic of skin diseases. In the study of skin cancer and burn wounds and more specifically as a methodology for diagnosis of cancer type and identification of skin penetration depth, it is of great relevance to investigate which cell types are present and how these are distributed at or below the skin surface. Consequently, a number of medical inspection techniques have been developed that can be used for the identification of malignant skin properties and more specifically skin cancer types. However, most of the existing techniques are increasingly contested because they either require destructive sampling (biopsy) or only measure on or under the skin surface (hyperspectral imaging) without identification of the penetration depth or detailed physiology of the maligned skin tissue. As a promising non-contact and non-destructive imaging technology, dynamic infrared thermography (DIRT) inspection will be used in combination with hyperspectral imaging (HSI) and physical modeling for fast and accurate skin property identification but also for assisted medical screening as it is possible to differentiate physiological properties based on a combined thermal-hyperspectral response of the skin. In order to optimize the accuracy and speed of tissue screening, the combined HS+IR measurement methodology will be assisted by numerical modeling.

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Depth-selective chemical imaging of Cultural Heritage Objects (DICHO). 01/10/2019 - 30/09/2023

Abstract

In spite of its ability to successfully characterize the condition and materials of paintings and other works of art in a non-invasive way, Macro X-Ray Fluorescence imaging (MA-XRF) suffers from a drawback that significantly affects its most valued application: revealing hidden features and overpainted compositions. While the penetrative properties of the primary and secondary X-rays can be used beneficially to reveal subsurface information that is crucial for art historical scholars and conservators, the extent to which a particular layer can be visualized selectively depends on the exclusive presence of an element in that layer. By consequence, layers with a similar elemental signature emerge intermixed in the same distribution image while the exact layer sequence remains unclear. As a result, in many cases, (contested) sample extraction proves mandatory in order to assign the detected elements to a specific layer within the paint stratigraphy. In order to augment chemical imaging with an additional depth-dimension, a dual approach is presented: (1) separating surface signals from deeper signals by expanding the MA-XRF detector angle geometry and exploiting the resulting, potential depth information that lies within the absorption effects on emission line ratios, by adding a level of data-processing to the existing protocol; (2) reconstructing the layer buildup and allocation of the detected signals by including an Infrared thermographic camera (IRT). In order to characterize the number of layers present and their sequence, multi-sine heat excitation will be exploited for the spectral range of 1.5-5μm in combination with dedicated post-processing of the hypercube images in the frequency domain. The proposed multimodal MA-XRF+IRT measurement methodology is developed on paint mockups and validated on historical paintings and wood panels, in collaboration with the Royal Museum of Fine Arts Antwerp.

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Optimized pre-processing using a response surface methodology for improved dynamic active thermographic inspections. 01/01/2019 - 31/12/2022

Abstract

Non-destructive testing using active thermography is still an expanding research area in order to achieve higher accuracy and faster measurements. More and more industrial manufacturers explore the opportunities of active thermography measurements resulting in more complex shapes and materials. Due to these evolutions it becomes nearly impossible to select the most applicable measurement setup in a fast manner. Especially inspections of large parts are a challenge since inspections of the complete part at once is not possible. Dynamic measurements are the solution to inspecting those samples, but consequently this implies new challenges regarding the measurement setup. In order to perform accurate inspections, trial and error is not a suitable solution because this working principle is time-consuming and should be redone every time the test sample changes, the measurement setup alters or when new innovations are discovered. The purpose of this research is to develop and implement an optimisation routine in order to give a suggestion of measurement setup parameters starting from finite element simulations and afterwards updating with knowledge of preliminary measurements. This optimisation routine will be performed using well-known response surface techniques and benchmarked with newly discovered methods. The optimisation routine will be tested on multiple samples in order to inspect the robustness and reliability.

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A combined IR, NIR and MA-XRF material inspection method 01/01/2019 - 31/12/2022

Abstract

In the study of historical paintings and as a preparation for restoration activities of such artefacts, it is of great relevance to investigate which materials and degradation products are present and how these are distributed at or below the painting surface. Consequently, a large number of analytical techniques have been developed that can be used for the identification of artists' materials. However, most of the existing techniques are increasingly contested because they require destructive sampling while in situ analysis with mobile equipment provides compositional data from only a limited number of individual points. In response, mobile scanning instruments for chemical imaging were developed, such as macro X-ray fluorescence (MA-XRF), that supply highly specific chemical information, but entail long scanning times for recording full spectra. As an alternative, thermography inspection is used for material parameter identification but also for art inspection as it is particularly fast. Therefore the goal of this research proposal is to eliminate the drawbacks of current inspection techniques by preceding the chemical speciation of different materials in a painting or surface layer (with XRF) with a swift chemical screening with thermography in the nearinfrared range. The resulting multi-sensor inspection methodology combines fast inspection with a slow inspection to achieve more accurate results and faster inspection times, including IR pigment identification algorithm.

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Fast broadband lock-in thermography for fragile structures using system identification. 01/01/2018 - 31/12/2020

Abstract

In this project a new methodology for product testing and quality control is developed based on infrared lock-in thermography. Infrared thermography permits to visualize the thermal/ warmup response of objects. In particular, lock-in thermography employs a sinusoidal light source to warm up the object being studied. Although pulsed thermography (PT) is commonly used as thermographic inspection technique, this method is not well suited for inspection of fragile structures (art and biological tissue inspection, blood circulation, …) due to the large instant energy emission which involves insufficient controllability and non-uniformity. On the other hand, with traditional lock-in thermography only one defect depth can be inspected at a time. In addition, at least one steady state period of the sine wave excitation is necessary to obtain quantitative results.

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Smart integration of numerical models and thermal inspection (SINT) 01/12/2017 - 30/11/2019

Abstract

Combining finite element models with non-destructive testing has enormous potential for valorization. The objective of this project is to develop a reliable damage detection and localization tool by combining NDT thermography data with FE modeling, making use of system identification. As the amount of experimental data is very high and depending on the resolution of the IR camera, the goal is to use virtual modeling in assistance of the NDT tests in order to gain accuracy and time-efficiency.

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Evaluation and simulation of the contact pressure in biological intercalary reconstruction surgery after bone sarcoma resection. 01/10/2017 - 30/09/2019

Abstract

Bone cancer affects children and young adults and requires wide removal of bone, leaving large defects. In order to save the limb and to restore its function in a lasting way, dead bone from bone banks or sterilised removed bone (graft) is used to fill the defect and is fixed by plates and screws. Still, in some patients a gap between the dead graft and the remaining living bone is seen, causing a delayed healing which leads to prolonged non-weight bearing periods (>1 year) and reoperations. We aim to reduce the healing time by introducing a predefined compression force to a graft, comparable to methods used in fracture fixation and megaprosthesis ingrowth. However, no literature is available evaluating the compression force and its effect on graft healing. Moreover, as bone cancer is extremely rare, this small patient group is often ignored for research funding to improve the current knowledge. We need to reproduce this compression force in a reliable way in different patients and different bone parts. Therefore we need to develop a standardised surgical procedure and determine the relation between the compression force and the surgical variables, eg screw positioning. Data from in vitro cyclic loading experiments and the patient's characteristics will be used for virtual simulation of compression force during level walking. These data will be essential for the future introduction and development of innovative techniques such as patient-specific instruments and implants.

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A multiscale approach to model early age thermo-hydro-mechanical behaviour of non-reinforced concrete. 01/11/2016 - 31/10/2020

Abstract

The integrity of non-reinforced concrete structures at early stages of construction depends on many factors. One of these is the formation of cracks, which may be crucial in some applications. This problem is of great relevance for deep geological disposal concepts which consider concrete as one of the principle engineered barrier components, and for which the expected service life is > 1000s of years. This is particularly the case within the current Belgian disposal concept in which heat emitting radioactive wastes are post-conditioned in concrete/steel containers, to be placed in a deep underground geological formation using a system of galleries supported by non-reinforced concrete lining. In the early stages of repository construction and waste emplacement, the mechanical integrity of the concrete components is of utmost importance from the point of view of safety and performance. The potential retrievability/reversibility of wastes within a prolonged time period after waste emplacement places additional performance requirements on these concrete structures, which must retain their structural integrity over this period. The principal objective of this PhD is to make a first attempt at developing and implementing a multiscale-based coupled thermo-hydro-mechanical model to study the early age behaviour of nonreinforced concrete. In particular, the PhD student will develop a mathematical model that captures cracking potential due to thermo-hydraulic-mechanical transient conditions. To a limited extent, a secondary objective is also envisaged in which small laboratory-scale experiments may be carried out to derive parameters of importance for the multiscale models as well as for validation purposes.

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Mechanical pathways in the onset and progression of cartilage lesions of the hip joint. 01/10/2016 - 30/09/2018

Abstract

The hip functions as a ball and socket joint, with cartilage layers that cover the joint surfaces on both sides protecting it from impacts and permitting smooth movements. When the cartilage is impaired by mechanical, infectious or inflammatory causes, the joint might eventually wear down - a disabling condition known as osteoarthritis. Recent literature indicates that up to 80% of all hip osteoarthritis cases might be related to subtle variations in the joint geometry.: These variations have been suggested to give rise to peak joint stresses and altered load distributions on the cartilage. Although the mechanism is getting increasingly recognized in the literature, profound understanding of its true impact is lacking. Further, the prevalence of these morphological variations is reported to be much higher than the actual number of patients presenting for treatment. The aim of this thesis is to explore the impact of variation in hip joint anatomy on load distribution during daily living activities. I intend to clarify the role of mechanical drivers in the onset and progression of cartilage lesions of the hip joint by means of advanced multidimensional statistics and personalized load and stress predictions. The final step of this thesis will be to gradually transfer these findings into clinical practice and at the operating theatre by providing virtual pre-surgical planning, accurately implemented during surgery, using state of the art navigation technology.

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Toward a pinhole-free model for a Time-of-Flight camera, furnishing featureless procedures for calibration and navigation. 01/10/2016 - 11/05/2018

Abstract

A new generation of digital cameras makes use of emitted light pulses, more precisely the time between the emission and the reception of the reflected pulse, for computing the depth of the viewed object. This "Time-of-Flight" principle is replacing other 3D-scan strategies such as stereovision and structured light. Though the concept and possibilities of a ToF-camera essentially differs from these that are offered by "classical" optical cameras, the computer vision community still falls back on proven methods for calibration and structure-from-motion issues. We propose new techniques, fully exploiting the Time-of-Flight power, avoiding detection and recognition of features in the image. In a further step, we intend to design a new camera model, more general than the familiar pinhole model, providing a uniform framework for both lateral as depth calibration of ToF-cameras. The theory will be validated by simulations and real experiments (executed by a computer driven robot manipulator). Finally, real life applications will be considered, in cooperation with some of our industrial partners.

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Thermal hyperspectral material characterization for Art Conservation based on hypercubes. 01/07/2016 - 31/12/2017

Abstract

In the study of historical paintings and more specifically as a preparation for restoration activities of such artefacts, it is of great relevance to investigate which materials and degradation products are present and how these are distributed at or below the painting surface. Commonly used non-destructive in situ methods such as X-ray fluorescence (XRF) and X-ray diffraction (XRD), are only used for spot analyses and require several minutes to record a spectrum from a single sample position, resulting in long scanning times required to record the data hypercubes. As an alternative, thermography inspection, as a non-contact and non-destructive technique is used for material parameter identification but also for art inspection as it is possible to differentiate chemical compounds. Therefore the goal of this research proposal is to improve non-invasive macroscopic material characterization of flat objects, both from an industrial and cultural heritage context, by augmenting existing elemental imaging technology with more species specific imaging of organic and inorganic compounds and this by combining the established X-ray based approaches with IR thermography and hyperspectral (HS) images. A combined X-ray, IR thermography and HS technique eliminates the disadvantages of these techniques and results in a faster measurement and material identification technique with respect to measurement time but also accuracy of the material parameter identification.

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Next generation of heterogeneous sensor networks (NEXOR). 01/01/2015 - 31/12/2020

Abstract

This project represents a research contract awarded by the University of Antwerp. The supervisor provides the Antwerp University research mentioned in the title of the project under the conditions stipulated by the university.

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Smart Data Clouds. 01/12/2014 - 30/11/2016

Abstract

This project represents a research agreement between the UA and on the onther hand IWT. UA provides IWT research results mentioned in the title of the project under the conditions as stipulated in this contract.

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Research team(s)

Mechanical pathways in the onset and progression of cartilage lesions of the hip joint. 01/10/2014 - 30/09/2016

Abstract

The hip functions as a ball and socket joint, with cartilage layers that cover the joint surfaces on both sides protecting it from impacts and permitting smooth movements. When the cartilage is impaired by mechanical, infectious or inflammatory causes, the joint might eventually wear down - a disabling condition known as osteoarthritis. Recent literature indicates that up to 80% of all hip osteoarthritis cases might be related to subtle variations in the joint geometry. These variations have been suggested to give rise to peak joint stresses and altered load distributions on the cartilage. Although the mechanism is getting increasingly recognized in the literature, profound understanding of its true impact is lacking. Further, the prevalence of these morphological variations is reported to be much higher than the actual number of patients presenting for treatment. The aim of this thesis is to explore the impact of variation in hip joint anatomy on load distribution during daily living activities. I intend to clarify the role of mechanical drivers in the onset and progression of cartilage lesions of the hip joint by means of advanced multidimensional statistics and personalized load and stress predictions. The final step of this thesis will be to gradually transfer these findings into clinical practice and at the operating theatre by providing virtual pre-surgical planning, accurately implemented during surgery, using state of the art navigation technology.

Researcher(s)

Research team(s)

Robust procedures for elliptic or ellipsoidal point clouds with noisy boundaries 01/07/2014 - 31/12/2015

Abstract

We focus on 2D point sets with an elliptic shape and 3D point sets with an ellipsoidal shape, e.g. in camera images or a data fusion setting. Noise on these data points forces us to look for robust procedures that derive the quantities we need. Motivating case study: Suppose that the image is taken by a calibrated camera from a ball with known radius, what is the position of this ball relative to the camera?

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