Tracking and modelling motion for biomechanical analysis

This thesis focuses on the problem of determining appropriate skeletal configurations for which a virtual animated character moves to desired positions as smoothly, rapidly, and as accurately as possible. During the last decades, several methods and techniques, sophisticated or heuristic, have been presented to produce smooth and natural solutions to the Inverse Kinematics (IK) problem. However, many of the currently available methods suffer from high computational cost and production of unrealistic poses. In this study, a novel heuristic method, called Forward And Backward Reaching Inverse Kinematics (FABRIK), is proposed, which returns visually natural poses in real-time, equally comparable with highly sophisticated approaches. It is capable of supporting constraints for most of the known joint types and it can be extended to solve problems with multiple end effectors, multiple targets and closed loops. FABRIK was compared against the most popular IK approaches and evaluated in terms of its robustness and performance limitations. This thesis also includes a robust methodology for marker prediction under multiple marker occlusion for extended time periods, in order to drive real-time centre of rotation (CoR) estimations. Inferred information from neighbouring markers has been utilised, assuming that the inter-marker distances remain constant over time. This is the first time where the useful information about the missing markers positions which are partially visible to a single camera is deployed. Experiments demonstrate that the proposed methodology can effectively track the occluded markers with high accuracy, even if the occlusion persists for extended periods of time, recovering in real-time good estimates of the true joint positions. In addition, the predicted positions of the joints were further improved by employing FABRIK to relocate their positions and ensure a fixed bone length over time. Our methodology is tested against some of the most popular methods for marker prediction and the results confirm that our approach outperforms these methods in estimating both marker and CoR positions. Finally, an efficient model for real-time hand tracking and reconstruction that requires a minimum number of available markers, one on each finger, is presented. The proposed hand model is highly constrained with joint rotational and orientational constraints, restricting the fingers and palm movements to an appropriate feasible set. FABRIK is then incorporated to estimate the remaining joint positions and to fit them to the hand model. Physiological constraints, such as inertia, abduction, flexion etc, are also incorporated to correct the final hand posture. A mesh deformation algorithm is then applied to visualise the movements of the underlying hand skeleton for comparison with the true hand poses. The mathematical framework used for describing and implementing the techniques discussed within this thesis is Conformal Geometric Algebra (CGA)

Hand tracking and bimanual movement understanding

Bimanual movements are a subset ot human movements in which the two hands move together in order to do a task or imply a meaning A bimanual movement appearing in a sequence of images must be understood in order to enable computers to interact with humans in a natural way This problem includes two main phases, hand tracking and movement recognition. We approach the problem of hand tracking from a neuroscience point ot view First the hands are extracted and labelled by colour detection and blob analysis algorithms In the presence of the two hands one hand may occlude the other occasionally Therefore, hand occlusions must be detected in an image sequence A dynamic model is proposed to model the movement of each hand separately Using this model in a Kalman filtering proccss the exact starting and end points of hand occlusions are detected We exploit neuroscience phenomena to understand the beha\ tour of the hands during occlusion periods Based on this, we propose a general hand tracking algorithm to track and reacquire the hands over a movement including hand occlusion The advantages of the algorithm and its generality are demonstrated in the experiments. In order to recognise the movements first we recognise the movement of a hand Using statistical pattern recognition methods (such as Principal Component Analysis and Nearest Neighbour) the static shape of each hand appearing in an image is recognised A Graph- Matching algorithm and Discrete Midden Markov Models (DHMM) as two spatio-temporal pattern recognition techniques are imestigated tor recognising a dynamic hand gesture For recognising bimanual movements we consider two general forms ot these movements, single and concatenated periodic We introduce three Bayesian networks for recognising die movements The networks are designed to recognise and combinc the gestures of the hands in order to understand the whole movement Experiments on different types ot movement demonstrate the advantages and disadvantages of each network

Designing a New Tactile Display Technology and its Disability Interactions

People with visual impairments have a strong desire for a refreshable tactile interface that can provide immediate access to full page of Braille and tactile graphics. Regrettably, existing devices come at a considerable expense and remain out of reach for many. The exorbitant costs associated with current tactile displays stem from their intricate design and the multitude of components needed for their construction. This underscores the pressing need for technological innovation that can enhance tactile displays, making them more accessible and available to individuals with visual impairments. This research thesis delves into the development of a novel tactile display technology known as Tacilia. This technology's necessity and prerequisites are informed by in-depth qualitative engagements with students who have visual impairments, alongside a systematic analysis of the prevailing architectures underpinning existing tactile display technologies. The evolution of Tacilia unfolds through iterative processes encompassing conceptualisation, prototyping, and evaluation. With Tacilia, three distinct products and interactive experiences are explored, empowering individuals to manually draw tactile graphics, generate digitally designed media through printing, and display these creations on a dynamic pin array display. This innovation underscores Tacilia's capability to streamline the creation of refreshable tactile displays, rendering them more fitting, usable, and economically viable for people with visual impairments

Cognitive Structures of Kinesthetic Space Reevaluating Rudolf Laban's Choreutics In the Context of Spatial Cognition and Motor Control

The choreutic conception of the spatial aspect of body movements (originated by Rudolf Laban) was reevaluated according to cognitive and motor control research. "Kinesthetic spatial cognition" (analogous to visual spatial cognition) was identified as the psychological realm of choreutic knowledge. Kinesthesia was identified as arising from sensory receptors throughout the body. Kinesthetic space was defined as spatial information derived from kinesthesia. Kinesthetic spatial cognition was defined as cognitive processes (eg. mental rehearsal) involving kinesthetic spatial knowledge. This concept of kinesthetic spatial cognition has not been heretofore explicitly developed in cognitive science. Elements of the choreutic conception were psychologically validated since they are also well identified in cognitive and motor research. These include how spatial information is defined relative to a reference system; kinesthetic spatial knowledge is based on a mental code of elemental locations; higher-order networks of locations are collected into map-like spatial images; and many symmetrical operations can be performed. Close similarities were identified between choreutic polyhedral-shaped cognitive maps of the "kinesphere" and the "trajectory formation" model. A choreutic prototype/deflection hypothesis posits that dimensions and diagonals serve as conceptual prototypes while actual body movement consists of deflections. Similar spatial prototypes were identified in visual spatial cognition, a kinesiological analysis supported the bodily tendency towards deflections, and this concurred with ergonomic measurements of the shape of the workspace. An experiment attempted to identify prototypes in kinesthetic spatial cognition. Categories of kinesthetic spatial information are distinguished within choreutics and dance. These were reevaluated according to perceptual processes and kinesiology. Choreutic topological forms deflecting across various kinespheric nets are analogous to N. Bernstein's conception of the "co-ordinational net of the motor field ... as oscillating like a cobweb in the wind". An experiment demonstrated that kinesthetic spatial information is organised into cognitive categories and that choreutic material and Labanotation symbols can be advantageously used in experimental research

The Role of Knowledge in Visual Shape Representation

This report shows how knowledge about the visual world can be built into a shape representation in the form of a descriptive vocabulary making explicit the important geometrical relationships comprising objects' shapes. Two computational tools are offered: (1) Shapestokens are placed on a Scale-Space Blackboard, (2) Dimensionality-reduction captures deformation classes in configurations of tokens. Knowledge lies in the token types and deformation classes tailored to the constraints and regularities ofparticular shape worlds. A hierarchical shape vocabulary has been implemented supporting several later visual tasks in the two-dimensional shape domain of the dorsal fins of fishes

Conference on Intelligent Robotics in Field, Factory, Service, and Space (CIRFFSS 1994), volume 1

The AIAA/NASA Conference on Intelligent Robotics in Field, Factory, Service, and Space (CIRFFSS '94) was originally proposed because of the strong belief that America's problems of global economic competitiveness and job creation and preservation can partly be solved by the use of intelligent robotics, which are also required for human space exploration missions. Individual sessions addressed nuclear industry, agile manufacturing, security/building monitoring, on-orbit applications, vision and sensing technologies, situated control and low-level control, robotic systems architecture, environmental restoration and waste management, robotic remanufacturing, and healthcare applications

Simulating Humans: Computer Graphics, Animation, and Control

People are all around us. They inhabit our home, workplace, entertainment, and environment. Their presence and actions are noted or ignored, enjoyed or disdained, analyzed or prescribed. The very ubiquitousness of other people in our lives poses a tantalizing challenge to the computational modeler: people are at once the most common object of interest and yet the most structurally complex. Their everyday movements are amazingly uid yet demanding to reproduce, with actions driven not just mechanically by muscles and bones but also cognitively by beliefs and intentions. Our motor systems manage to learn how to make us move without leaving us the burden or pleasure of knowing how we did it. Likewise we learn how to describe the actions and behaviors of others without consciously struggling with the processes of perception, recognition, and language

A TALE OF TWO CITIES: DIET, HEALTH AND MIGRATION IN POST-MEDIEVAL COVENTRY AND CHELSEA THROUGH BIOGRAPHICAL RECONSTRUCTION, OSTEOARCHAEOLOGY AND ISOTOPE BIOGEOCHEMISTRY

Biogeochemical research has over the past four-and-a-half decades improved our understanding of human interaction with past environments. The application of different isotope systems has allowed archaeologists to interpret ancient diet, migration and pollution. Although well established in archaeology, biogeochemical interpretations are burdened with questions not only as to the methodology employed but also whether the data presents a consistent picture of past human activity. The use of biographically identifiable individuals offers a means by which the isotope systems may be tested against extent documentary evidence. A sample of forty-five individuals, almost half of which were named individuals, were obtained from the sites of Holy Trinity (Coventry) and St. Luke's (Old Street, Chelsea) and the stable isotopes of carbon, nitrogen, oxygen, strontium and lead analysed. The biographies ofthe named individuals were reconstructed through analysis ofextant historical documentation and' used to provide a framework of interpretation for the biogeochemical teclmiques applied. Comparisons are made between the two sites in relation to the biogeochemical techniques employed, biographical reconstruction and osteoarchaeological evidence for disease, migration and diet to address methodological issues and broader questions on 'i,ndustrialisation' during the eighteenth and nineteenth centuries. The osteoarchaeological evidence suggests separation of the two groups into discrete' populations, one that is characterised by occupationally-derived osteoarthropathies (Coventry), and the second, Chelsea, which has an absence of these pathologies. This supports the historical character of the t\VO cities: Coventry as an industrial city in contrast to Chelsea, a 'village of palaces' or pleasure resort. Biogeochemically, carbon and nitrogen isotopes revealed a picture of status-based access to protein resources in a diet that is particularly dominated by freshwater fish, terrestrial omnivores such as pig, or a combination of the two. There is, however, little evidence for a difference in access to such resources between the sexes. Likewise, strontium and oxygen isotopes are capable of differentiating between the two populations and therefore in identifying local and migrant individuals, though limitations in the sample prevent the full utilisation of this data. In one case (Milborough Maxwell) the isotopic techniques \vere able to reveal trans-Atlantic migration between England and the Caribbean. Analysis of lead isotopes of the two populations indicates that while there is little to differentiate the two sites, heavy metal exposure is greater for the eighteenth and nineteenth centuries than for previous periods.EThOS - Electronic Theses Online ServiceGBUnited Kingdo