Active shape models with focus on overlapping problems applied to plant detection and soil pore analysis

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Analysis of the inspection of mechanical parts using dense range data

More than ever, efficiency and quality are key words in modern industry. This situation enhances the importance of quality control and creates a great demand for cheap and reliable automatic inspection systems. Taking into account these facts and the demand for systems able to inspect the final shape of machined parts, we decided to investigate the viability of automatic model-based inspection of mechanical parts using the dense range data produced by laser stripers. Given a part to be inspected and a corresponding model of the part stored in the model data base, the first step of inspecting the part is the acquisition of data corresponding to the part, in our case this means the acquisition of a range image of it. In order to be able to compare the part image and its stored model, it is necessary to align the model with the range image of the part. This process, called registration, corresponds to finding the rigid transformation that superposes model and image. After the image and model are registered, the actual inspection uses the range image to verify if all the features predicted in the model are present and have the right pose and dimensions. Therefore, besides the acquisition of range images, the inspection of machined parts involves three main issues: modelling, registration and inspection diagnosis. The application, for inspection purposes, of the main representational schemes for modelling solid objects is discussed and it is suggested the use of EDT models (see [Zeid 91]). A particular implementation of EDT models is presented. A novel approach for the verification of tolerances during the inspection is proposed. The approach allows not only the inspection of the most common tolerances described in the tolerancing standards, but also the inspection of tolerances defined according to Requicha's theory of tolerancing (see [Requicha 83]). A model of the sensitivity and reliability of the inspection process based on the modelling of the errors during the inspection process is also proposed. The importance of the accuracy of the registration in different inspections tasks is discussed. A modified version of the ICP algorithm (see [Besl &; McKay 92]) for the registration of sculptured surfaces is proposed. The maximum accuracy of the ICP algorithm, as a function of the sensor errors and the number of matched points, is determined. A novel method for the measurement and reconstruction of waviness errors on sculp¬ tured surfaces is proposed. The method makes use of the 2D Discrete Fourier Transform for the detection and reconstruction of the waviness error. A model of the sensitivity and reliability of the method is proposed. The application of the methods proposed is illustrated using synthetic and real range image

The influence of particle characteristics on the engineering behaviour of granular materials

Imperial Users onl

Analysis of Some Textured Images by Transputer

Texture, as a visual perception, can be easily seen by eye and often described without much difficulty. However, textural recognition and measurement by machine is a very different issue and has only recently been developed. In this thesis, a whole set of new algorithms have been developed to analyse textured images with particular reference to the requirements of soil microstructural applications. The new technology of parallel processing is used to implement and improve the complicated computations

Development of new intelligent autonomous robotic assistant for hospitals

Continuous technological development in modern societies has increased the quality of life and average life-span of people. This imposes an extra burden on the current healthcare infrastructure, which also creates the opportunity for developing new, autonomous, assistive robots to help alleviate this extra workload. The research question explored the extent to which a prototypical robotic platform can be created and how it may be implemented in a hospital environment with the aim to assist the hospital staff with daily tasks, such as guiding patients and visitors, following patients to ensure safety, and making deliveries to and from rooms and workstations. In terms of major contributions, this thesis outlines five domains of the development of an actual robotic assistant prototype. Firstly, a comprehensive schematic design is presented in which mechanical, electrical, motor control and kinematics solutions have been examined in detail. Next, a new method has been proposed for assessing the intrinsic properties of different flooring-types using machine learning to classify mechanical vibrations. Thirdly, the technical challenge of enabling the robot to simultaneously map and localise itself in a dynamic environment has been addressed, whereby leg detection is introduced to ensure that, whilst mapping, the robot is able to distinguish between people and the background. The fourth contribution is geometric collision prediction into stabilised dynamic navigation methods, thus optimising the navigation ability to update real-time path planning in a dynamic environment. Lastly, the problem of detecting gaze at long distances has been addressed by means of a new eye-tracking hardware solution which combines infra-red eye tracking and depth sensing. The research serves both to provide a template for the development of comprehensive mobile assistive-robot solutions, and to address some of the inherent challenges currently present in introducing autonomous assistive robots in hospital environments.Open Acces

Pattern Recognition

A wealth of advanced pattern recognition algorithms are emerging from the interdiscipline between technologies of effective visual features and the human-brain cognition process. Effective visual features are made possible through the rapid developments in appropriate sensor equipments, novel filter designs, and viable information processing architectures. While the understanding of human-brain cognition process broadens the way in which the computer can perform pattern recognition tasks. The present book is intended to collect representative researches around the globe focusing on low-level vision, filter design, features and image descriptors, data mining and analysis, and biologically inspired algorithms. The 27 chapters coved in this book disclose recent advances and new ideas in promoting the techniques, technology and applications of pattern recognition

Design and testing of additively manufactured lattice structures for musculoskeletal applications

Additive manufacturing (AM) methods present a new frontier in engineering, allowing the fabrication of porous lattice structures with tailored mechanical properties. AM structures can be made using bio-inert metals, creating controlled stiffness biomaterials. As bone formation is strain dependent, these AM biomaterials can be used in implants to optimise the strain in surrounding trabecular bone for peak bone formation. However, the behaviour of AM lattices varies and is subject to manufacturing constraints. The aim of this PhD was to investigate the mechanical behaviour of AM lattices, and maximise the clinical benefits of AM for musculoskeletal applications. Lattice architecture was shown to affect the anisotropy of an AM lattice biomaterial, increasing the stiffness in directions not often tested in the literature. The mechanical and morphological properties of individual struts within powder bed fusion (PBF) lattices were also shown to vary depending on the orientation of the struts to the build direction. The ultimate tensile strength of titanium alloy (Ti6Al4V) struts more than doubled when built at a low angle versus perpendicular to the build platform, and other properties were substantially lower than for the bulk material. Geometric imperfections were found for struts built at low angles. As such, a low stiffness modified stochastic lattice was designed and tested which avoided the problems found with struts built at low angles. The resulting lattice had improved stiffness isotropy and could be used for musculoskeletal applications, tuned to match the mechanical properties in local trabecular bone and enhancing bone formation.Open Acces