A STUDY OF MACHINE VISION IN THE AUTOMOTIVE INDUSTRY

With the growth of industrial automation, it has become increasingly important to validate the quality of every manufactured part during production. Until now, human visual inspection aided with hard tooling or machines have been the primary means to this end, but the speed of today's production lines, the complexity of production equipment and the highest standards of quality to which parts must adhere frequently, make the traditional methods of industrial inspection and control impractical, if not impossible. Subsequently, new solutions have been developed for the monitoring and control of industrial processes, in real­time. One such technology is the area of machine vision. After many years of research and development, computerised vision systems are now leaving the laboratory and are being used successfully in the factory environment. They are both robust and competitively priced as a sensing technique which has now opened up a whole new sector for automation. Machine vision systems are becoming an important integral part of the automotive manufacturing process, with applications ranging from inspection, classification, robot guidance, assembly verification through to process monitoring and control. Although the number of systems in current use is still relatively small, there can be no doubt, given the issues at stake, that the automotive industry will once again lead the way with the implementation of machine vision just as it has done robotic technology. The thesis considered the issue of machine vision and in particular, its deployment within the automotive industry. The thesis has presented work on machine vision for the prospective end-user and not the designer of such systems. It will provide sufficient background about the subject, to separate machine vision promises from reality and permit intelligent decisions regarding machine vision applications to be made. The initial part of the dissertation focussed on the strategic issues affecting the selection of machine vision at the planning stage, such as a listing of the factors to justify investment, the capability of the technology and type of problems that are associated with this relatively new but complex science. Though it is widely accepted that no two industrial machine vision systems are identical, knowledge of the basic fundamentals which underpin the structure of the technology in its application is presented. This work covered a structured description detailing typical hardware components such as camera technology, lighting systems, etc... which form an integral part of an industrial system and discussions regarding the criteria for selection are presented. To complement this work, a further section is specifically devoted to the bewildering array of vision software analysis techniques which are currently available today. A detailed description of the various techniques that are applied to images in order to make use of and understand the data contained within them are discussed and explored. Applications for machine vision fall into two main categories namely robotic guidance and inspection. Obviously within each category there are many further sub­groups. Within this context the latter part of the thesis reviews with a well structured description of several industrial case studies derived from the automotive industry, which illustrate that machine vision is capable of providing real time solutions to manufacturing based problems. In conclusion, despite the limited availability of industrially based machine vision systems, the success of implementation is not always guaranteed, as the technology imposes both technical limitations and introduce new human engineering considerations. By understanding the application and the implications of the technical requirements on both the "staging" and the "image-processing" power required of the machine vision system. The thesis has shown that the most significant elements of a successful application are indeed the lighting, optics, component design, etc... - the "Staging". From the case studies investigated, optimised "staging" has resulted in the need for less computing power in the machine vision system. Inevitably, greater computing power not only requires more time but is generally more expensive. The experience gained from the this project, has demonstrated that machine vision technology is a realistic alternative means of capturing data in real-time. Since the current limitations of the technology are well suited to the delivery process of the quality function within the manufacturing process

Three-dimensional geometry characterization using structured light fields

Tese de doutoramento. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 200

On the popularization of digital close-range photogrammetry: a handbook for new users.

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Γεωπληροφορική

The development of a non-contact co-ordinate measurement machine

Bibliography: pages 113-117.The Department of Surveying and Geodetic Engineering at the University of Cape Town, in conjunction with the Department of Mechanical Engineering at the University of Cape Town have developed a non-contact co-ordinate measurement machine in a project called MILIMAP. The project had the following objectives : 1. To determine unique surface co-ordinates for continuous, complex objects with submillimetre accuracy. 2. The representation of the co-ordinates was to be in a format that could be utilised by a computer numerically controlled (CNC) milling machine in a computer aided design/ computer aided manufacture (CADCAM) environment. 3. The device had to use a non-contact method for data capture. The MILIMAP project was undertaken because there is a demand for co-ordinate measurement machines in industry for the inspection of objects for quality control purposes. Conventional Co-ordinate Measurement Machines (CMMs) are expensive and use a contact probe to measure the object. The contact probe measurement technique is unsuitable for the measurement of non-rigid objects such as shoes and automobile seat padding. The MILIMAP system provides a noncontact measurement technique that can be applied to non-rigid as well as rigid objects. Additional applications in the archaeological field exist for the non-contact measurement of sensitive, historical artefacts. A digital photogrammetric system was developed to measure the position of a laser dot projected onto the surface of the measurement object. This measurement system satisfied the criteria of a non-contact measurement method required for the project. The system utilised three digital CCD cameras to capture images of the laser dot projected onto the object. Image processing software, developed from existing software within the Department of Surveying and Geodetic Engineering, was used to photogrammetrically determine the co-ordinates of the laser dot to sub-millimetre accuracy on the surface of the object. A mechanical device was designed and constructed by the Department of Mechanical Engineering in order to move the laser over the surface of the object, and to rotate the object. The entire surface of the object could be measured by the system using these operations

Semi-automated geomorphological mapping applied to landslide hazard analysis

Computer-assisted three-dimensional (3D) mapping using stereo and multi-image (“softcopy”) photogrammetry is shown to enhance the visual interpretation of geomorphology in steep terrain with the direct benefit of greater locational accuracy than traditional manual mapping. This would benefit multi-parameter correlations between terrain attributes and landslide distribution in both direct and indirect forms of landslide hazard assessment. Case studies involve synthetic models of a landslide, and field studies of a rock slope and steep undeveloped hillsides with both recently formed and partly degraded, old landslide scars. Diagnostic 3D morphology was generated semi-automatically both using a terrain-following cursor under stereo-viewing and from high resolution digital elevation models created using area-based image correlation, further processed with curvature algorithms. Laboratory-based studies quantify limitations of area-based image correlation for measurement of 3D points on planar surfaces with varying camera orientations. The accuracy of point measurement is shown to be non-linear with limiting conditions created by both narrow and wide camera angles and moderate obliquity of the target plane. Analysis of the results with the planar surface highlighted problems with the controlling parameters of the area-based image correlation process when used for generating DEMs from images obtained with a low-cost digital camera. Although the specific cause of the phase-wrapped image artefacts identified was not found, the procedure would form a suitable method for testing image correlation software, as these artefacts may not be obvious in DEMs of non-planar surfaces.Modelling of synthetic landslides shows that Fast Fourier Transforms are an efficient method for removing noise, as produced by errors in measurement of individual DEM points, enabling diagnostic morphological terrain elements to be extracted. Component landforms within landslides are complex entities and conversion of the automatically-defined morphology into geomorphology was only achieved with manual interpretation; however, this interpretation was facilitated by softcopy-driven stereo viewing of the morphological entities across the hillsides.In the final case study of a large landslide within a man-made slope, landslide displacements were measured using a photogrammetric model consisting of 79 images captured with a helicopter-borne, hand-held, small format digital camera. Displacement vectors and a thematic geomorphological map were superimposed over an animated, 3D photo-textured model to aid non-stereo visualisation and communication of results

Electronic Imaging & the Visual Arts. EVA 2015 Florence

Information Technologies of interest for Culture Heritage are presented: multimedia systems, data-bases, data protection, access to digital content, Virtual Galleries. Particular reference is reserved to digital images (Electronic Imaging & the Visual Arts), regarding Cultural Institutions (Museums, Libraries, Palace – Monuments, Archaeological Sites). The International Conference includes the following Sessions: Strategic Issues; New Technologies & Applications; New 2D-3D Technical Developments & Applications; Virtual Galleries – Museums and Related Initiatives; Access to the Culture Information. Two Workshops regard: International Cooperation; Innovation and Enterprise

THE APPLICATION OF REMOTE SENSING TECHNIQUES IN HYDROLOGY

REMOTE SENSING, which may be simplistically defined as ’the collection and interpretation of emitted or reflected radiation from a body’, offers the potential for accurate interpolation of surface data and even for its direct measurement on scales ranging from local to world wide. This dissertation has been written primarily for the hydrologist, engineer, environmentalist or student who needs to measure changes either in space or time of hydrological variables such as water quality, but who has little practical knowledge of remote sensing or how it may be of assistance to him. It may be regarded as a reference document which, as a result of internal cross referencing and comprehensive external subject referencing, should enable the reader to acquire a background knowledge of remote sensing theory which is relevant to his interests, to understand the advantages and difficulties of applying remote sensing techniques to his measurement problem and to obtain further information about remote sensing applications which have already been undertaken within his field of interest. The dissertation centres on the hydrological situation in England and Wales by initially outlining the structure of their water industries. The main hydrological measurement objectives in terms of water resources, water supply, effluent disposal and flood prediction and warning are identified and some advantages of incorporating remote sensing into hydrological measurement programmes are suggested. The physical theory of remote sensing is described and the main methods of collecting and analysing remotely sensed data are given. A topic by topic analysis of the most suitable ways of tackling specific hydrological measurement problems through the use of remote sensing is made and the dissertation concludes with an assessment of the likely future use of remote sensing in hydrological measurement programmes in genera

Application of optical techniques to surveying

This thesis addresses the problem of acquiring spatial data concerning points on the surface of structures such as underground tunnels and sewers. These data can usefully provide knowledge of deformation, shape, area, volume, and position of structures. Such data can be further analysed to give insight into clearances, deterioration, flow rates and in-fill volumes or can be used to give knowledge of the present state of structures and their position. Few systems address the problem of reliably acquiring this data in a manner that is fast and accurate while remaining flexible, adaptable and robust. This thesis considers a solution to the problem of fast and accurate spatial data acquisition concerning commonly found structures using the technique of optical triangulation with a linear array camera and diode laser light source. Optical triangulation is a technique that has not fully matured for medium range measurement with few systems having been developed and little research material produced. However, the research carried out for this thesis shows that providing all the factors that contribute errors of measurement are understood, then a fast, robust and high accuracy system can be developed. The development of the optical triangulation technique for use in surveying was addressed through a programme of prototype development, testing, and refinement. Three prototypes were built that demonstrated the reliability, accuracy, speed and robustness of this technique. The errors associated with the a triangulation measuring system when applied to surveying application is considered from the intrinsic errors which are the same for any triangulation system and the extrinsic errors which are particular to the use of this system in surveying situations. A calibration bench was constructed for consideration of the triangulation system which was automatic and used an interferometer to provide high accuracy measurement of the performance of the triangulation system. Calibration and interpolation trials were conducted and the results analysed. An analysis of the subpixel accuracy achieved with the discrete pixel CCD imagers has been performed and an analysis made. One of the main disadvantages of optical triangulation when applied to the range 0-5 metres is that of non-linearity. A method of correction has been developed and analysed which is believed to be novel and makes a significant improvement to the measuring system. The conclusion of this research is that an improved system of measurement has been produced which has a number of novel features. Trials show that the measuring system could be developed commercially to provide a solution to measurements of structures within the range of the device and with greater accuracy than comparable equipment designed for the same purpose

ULTRA CLOSE-RANGE DIGITAL PHOTOGRAMMETRY AS A TOOL TO PRESERVE, STUDY, AND SHARE SKELETAL REMAINS

Skeletal collections around the world hold valuable and intriguing knowledge about humanity. Their potential value could be fully exploited by overcoming current limitations in documenting and sharing them. Virtual anthropology provides effective ways to study and value skeletal collections using three-dimensional (3D) data, e.g. allowing powerful comparative and evolutionary studies, along with specimen preservation and dissemination. CT- and laser scanning are the most used techniques for three-dimensional reconstruction. However, they are resource-intensive and, therefore, difficult to be applied to large samples or skeletal collections. Ultra close-range digital photogrammetry (UCR-DP) enables photorealistic 3D reconstructions from simple photographs of the specimen. However, it is the least used method in skeletal anthropology and the lack of appropriate protocols often limit the quality of its outcomes. This Ph.D. thesis explored UCR-DP application in skeletal anthropology. The state-of-the-art of this technique was studied, and a new approach based on cloud computing was proposed and validated against current gold standards. This approach relies on the processing capabilities of remote servers and a free-for-academic use software environment; it proved to produce measurements equivalent to those of osteometry and, in many cases, they were more precise than those of CT-scanning. Cloud-based UCR-DP allowed the processing of multiple 3D models at once, leading to a low-cost, quick, and effective 3D production. The technique was successfully used to digitally preserve an initial sample of 534 crania from the skeletal collections of the Museo Sardo di Antropologia ed Etnografia (MuSAE, Università degli Studi di Cagliari). Best practices in using the technique for skeletal collection dissemination were studied and several applications were developed including MuSAE online virtual tours, virtual physical anthropology labs and distance learning, durable online dissemination, and values-led participatorily designed interactive and immersive exhibitions at the MuSAE. The sample will be used in a future population study of Sardinian skeletal characteristics from the Neolithic to modern times. In conclusion, cloud-based UCR-DP offers many significant advantages over other 3D scanning techniques: greater versatility in terms of application range and technical implementation, scalability, photorealistic restitution, reduced requirements relating to hardware, labour, time, and cost, and is, therefore, the best choice to document and value effectively large skeletal samples and collections