Introduction: Instrumented gait analysis and inverse dynamics are commonly used in research and clinical practice to calculate lower extremity joint kinetics, such as power and work. However, multisegment foot (MSF) model kinetics have been limited by ground reaction force (GRF) measurements. New technology enables simultaneous capture of plantar pressure and shear stress distributions but has not yet been used with motion capture. Integrating MSF models and pressure/shear measurements will enhance the analysis of foot joint kinetics. The purpose of this study was to develop methodology to integrate these systems, then analyze the effects of speed on foot joint kinetics. Methods: Custom software was developed to synchronize motion capture and pressure/shear data using measured offsets between reference frame origins and time between events. Marker trajectories were used to mask pressure/shear data and construct segment specific GRFs. Inverse dynamics were done in commercial software. Demonstrative data was from 5 healthy adults walking unshod at 3 fixed speeds (1.0, 1.3, and 1.6 m/s, respectively) wearing retroreflective markers according to an MSF model. Plantar shear forces and ankle, midtarsal, and first metatarsophalangeal (MTP) joint kinetics were reported. Speed effects on joint net work were evaluated with a repeated measures ANOVA. Results: Plantar shear forces during stance showed some spreading effects (directionally opposing shear forces) that relatively were unaffected by walking speed. Midtarsal joint power seemed to slightly lag behind the ankle, particularly in late stance. Net work at the ankle (p = 0.024), midtarsal (p = 0.023), and MTP (p = 0.009) joints increased with speed. Conclusions: Functionally, the ankle and midtarsal joints became more motorlike with increasing speed by generating more energy than they absorbed, while the MTP joint became more damperlike by absorbing more energy than it generated. System integration appears to be an overall success. Limitations and suggestions for future work are presented.

No description available.

Fotorealistische Modellierung von Menschen ist in der Computer Grafik von besonderer Bedeutung, da diese allgegenwärtig in Film- und Computerspiel-Produktionen benötigt wird. Heutige Modellierungs-Software vereinfacht das Generieren realistischer Modelle. Hingegen ist das Erstellen realitätsgetreuer Abbilder real existierender Personen nach wie vor eine anspruchsvolle Aufgabe. Die vorliegende Arbeit adressiert die automatische Modellierung von realen Menschen und die Verfolgung ihrer Bewegung. Ein Skinning-basierter Ansatz wurde gewählt, um effizientes Generieren von Animationen zu ermöglichen. Für gesteigerte Realitätstreue wurde eine artefaktfreie Skinning-Funktion um den Einfluss mehrerer kinematischer Gelenke erweitert. Dies ermöglicht eine große Vielfalt an real wirkenden komplexen Bewegungen. Zum Erstellen eines Personen-spezifischen Modells wird hier ein automatischer, datenbasierter Ansatz vorgeschlagen. Als Eingabedaten werden registrierte, geschlossene Beispiel-Meshes verschiedener Posen genutzt. Um bestmöglich die Trainingsdaten zu approximieren, werden in einer Schleife alle Komponenten des Modells optimiert: Vertices, Gelenke und Skinning-Gewichte. Zwecks Tracking von Sequenzen verrauschter und nur teilweise erfasster 3D Rekonstruktionen wird ein markerfreier modelladaptiver Ansatz vorgestellt. Durch die nicht-parametrische Formulierung werden die Gelenke des generischen initialien Tracking-Modells uneingeschränkt optimiert, als auch die Oberfläche frei deformiert und somit individuelle Eigenheiten des Subjekts extrahiert. Integriertes a priori Wissen über die menschliche Gestalt, extrahiert aus Trainingsdaten, gewährleistet realistische Modellanpassungen. Das resultierende Modell mit Animationsparametern ist darauf optimiert, bestmöglich die Eingabe-Sequenz wiederzugeben. Zusammengefasst ermöglichen die vorgestellten Ansätze realitätsgetreues und automatisches Modellieren von Menschen und damit akkurates Tracking aus 3D Daten. / Photorealistic modeling of humans in computer graphics is of special interest because it is required for modern movie- and computer game productions. Modeling realistic human models is relatively simple with current modeling software, but modeling an existing real person in detail is still a very cumbersome task. This dissertation focuses on realistic and automatic modeling as well as tracking human body motion. A skinning based approach is chosen to support efficient realistic animation. For increased realism, an artifact-free skinning function is enhanced to support blending the influence of multiple kinematic joints. As a result, natural appearance is supported for a wide range of complex motions. To setup a subject-specific model, an automatic and data-driven optimization framework is introduced. Registered, watertight example meshes of different poses are used as input. Using an efficient loop, all components of the animatable model are optimized to closely resemble the training data: vertices, kinematic joints and skinning weights. For the purpose of tracking sequences of noisy, partial 3D observations, a markerless motion capture method with simultaneous detailed model adaptation is proposed. The non-parametric formulation supports free-form deformation of the model’s shape as well as unconstrained adaptation of the kinematic joints, thereby allowing to extract individual peculiarities of the captured subject. Integrated a-prior knowledge on human shape and pose, extracted from training data, ensures that the adapted models maintain a natural and realistic appearance. The result is an animatable model adapted to the captured subject as well as a sequence of animation parameters, faithfully resembling the input data. Altogether, the presented approaches provide realistic and automatic modeling of human characters accurately resembling sequences of 3D input data.

Virtual Reality (VR) is a creative tool that enables immersive learning, planning and training of surgical operations. Extensive research has been conducted in multiple surgical specialities where VR has been utilized, such as spinal neurosurgery. However, cranial neurosurgery remains relatively unexplored in this regard. The thesis project presented here explores the impact of adopting VR, using a headset and controllers, to study the cranial neurosurgical procedure of External Ventricular Drainage (EVD). In this study, pre-recorded Motion Captured (MoCap) data of an EVD procedure is visualised on a desktop monitor as well as through a VR headset. Participants were tasked with identifying and marking one key moment in the recordings. Both objective and subjective metrics were recorded, such as completion time, accuracy, precision, the usage of different interaction controls as well as through the use of a questionnaire. The comparison is done on an objective and subjective scale, analysing user performance and User Experience (UX). The results from the experiment showed that the task was completed on average twice as fast in VR compared to desktop. However, desktop showed more promise in having higher accuracy and precision. Subjective feedback showed a slightly higher preference towards the VR environment concerning system usability. However, the settings were equally comparable in terms of task load. Furthermore, a guidance laser introduced to help with depth perception showed no increase in user performance. In conclusion, VR displays promise as an alternative tool to be used for planning and educational purposes in cranial surgery. Potential future developments could focus on the increased precision in interactive in VR, with the aid of haptic feedback, minor adjustments and scalability. / Virtuell verklighet (VR) är ett kreativt verktyg som möjliggör ett fördjupat lärande, planering och träning av kirurgiska operationer. Omfattande forskning av VR har utförts inom kirurgiska specialiseringar, såsom spinal neurokirurgi. Den kraniala neurokirurgin är dock relativt outforskad i detta avseende. I det här examensarbetet undersöks effekten av att applicera VR för att kunna studera det kraniala neurokirurgiska ingreppet kallat Externt Ventrikulärt Dränage (EVD). I denna studie visualiserades förinspelad Motion Captured (MoCap) data från en EVD-procedur på en stationär bildskärm såväl som genom ett VR-headset. Deltagarna fick i uppdrag att identifiera och markera ett nyckelmoment i inspelningarna. Både objektiva och subjektiva mått registrerades, såsom slutförandetid, noggrannhet, precision, användningen av olika interaktionskontroller samt genom användning av ett frågeformulär. Jämförelsen gjordes på en objektiv och subjektiv skala, med en analys av användarprestanda (UP) och användarupplevelse (UX). Resultaten från experimentet visade att uppgiften genomfördes i genomsnitt dubbelt så snabbt i VR. Dock visade uppsättningen med vanlig bildskärm mer lovande i form av att vara mer exakt i markörplacering och identifiering av bildrutorna. Användarenkäten visade en något högre preferens för VR-miljön vad gäller system-användbarhet. Miljöerna var dock lika jämförbara när det gäller uppgiftsbelastning. Dessutom visade en styrlaser ingen ökning av UP, fastän den introducerades för att hjälpa till med djupsyn. Sammanfattningsvis visade VR lovande resultat för att kunna användas som ett alternativt verktyg för planering och utbildningsändamål inom kranialkirurgi. Potentiell framtida utveckling kan fokusera på ökad precisionen av svårhanterlighet i VR, med hjälp av haptisk vibration, justeringar för precision och skalbarhet. Dessutom kan det undersökas hur de två systemen jämförs när båda optimeras efter och drar nytta av sina egna styrkor.

MScEng / Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009. / Clinical gait analysis has been proven to greatly improve treatment planning and monitoring of patients suffering from neuromuscular disorders. Despite this fact, it was found that gait analysis is still largely underutilised in general patient-care due to limitations of gait measurement equipment. Inertial motion capture (IMC) is able to overcome many of these limitations, but this technology is relatively untested and is therefore viewed as adolescent. This study addresses this problem by evaluating the validity and repeatability of gait parameters measured with a commercially available, full-body IMC system by comparing the results to those obtained with alternative methods of motion capture. The IMC system’s results were compared to a trusted optical motion capture (OMC) system’s results to evaluate validity. The results show that the measurements for the hip and knee obtained with IMC compares well with those obtained using OMC – with coefficient-of-correlation (R) values as high as 0.99. Some discrepancies were identified in the ankle-joint validity results. These were attributed to differences between the two systems with regard to the definition of ankle joint and to non-ideal IMC system foot-sensor design. The repeatability, using the IMC system, was quantified using the coefficient of variance (CV), the coefficient of multiple determination (CMD) and the coefficient of multiple correlation (CMC). Results show that IMC-recorded gait patterns have high repeatability for within-day tests (CMD: 0.786-0.984; CMC: 0.881-0.992) and between-day tests (CMD: 0.771-0.991; CMC: 0.872-0.995). These results compare well with those from similar studies done using OMC and electromagnetic motion capture (EMC), especially when comparing between-day results. Finally, to evaluate the measurements from the IMC system in a clinically useful application, a neural network was employed to distinguish between gait strides of stroke patients and those of able-bodied controls. The network proved to be very successful with a repeatable accuracy of 99.4% (1/166 misclassified). The study concluded that the full-body IMC system produces sufficiently valid and repeatable gait data to be used in clinical gait analysis, but that further refinement of the ankle-joint definition and improvements to the foot sensor are required.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Optical motion capture (Mocap) systems measure 3D human kinematics accurately and at high sample rates. One of the limitations of these systems is that they can only be used indoors. However, advances in inertial sensing have led to the development of inertial Mocap technology (IMCT). IMCT measures kinematics using inertial measurement units (IMUs) attached to a subject's body without the need for external sensors. It is thus completely portable which opens up new horizons for clinical Mocap. This study evaluates the use of IMCT for improving road cycling kinematics. Ten male sub-elite cyclists were recorded with an IMCT system for one minute while cycling at 2, 3.5 and 5.5 W.kg-1 on a stretch of road and on a stationary trainer. A benchmark test was also done where cycling kinematics was measured simultaneously with the IMCT and a gold-standard Vicon optical system. The first goal was to assess the feasibility of conducting field measurements of cycling kinematics. Magnetic analysis results showed that the IMUs near the pedals and handlebars experienced significant magnetic interference (up to 50% deviation in intensity) from ferrous materials in the road bicycles, causing significant errors in kinematic measurement. Therefore, it was found that the IMCT cannot measure accurate full-body kinematics with the subject on a road bicycle. However, the results of the benchmark test with the Vicon showed that the IMCT can still measure accurate hip (root mean square error (RMSE) < 1°), knee (RMSE < 3.5°) and ankle (RMSE < 3°) flexion using its Kinematic Coupling algorithm. The second goal was to determine whether there is a significant difference between road cycling kinematics captured on the road and in a laboratory. The outdoor flexion results were significantly different to the indoor results, especially for minimum flexion (P < 0.05 for all joints). Changes in rider kinematics between high and low power were also found to have significantly more variability on the road (R2 = 0.36, 0.61, 0.08) than on the trainer (R2 = 0.93, 0.89, 0.56) for the hip, knee and ankle joints respectively. These results bring into question the ecological validity of laboratory cycling. Lastly, applications of IMCT for optimizing cycling performance were to be identified. Several aspects of kinematic analysis and performance optimization using the IMCT were evaluated. It was determined that IMCT is most suited for use as a dynamic bicycle fitting tool for analysis of biomechanical efficiency, bilateral asymmetry and prevention of overuse injuries. Recommendations for future work include the elimination of the magnetic interference and integration of the IMCT data with kinetic measurements to develop an outdoor dynamic fitting protocol. / AFRIKAANSE OPSOMMING: Optiese bewegingswaarnemingstelsels (BWS) meet drie-dimensionele menslike kinematika met hoë akkuraatheid en teen hoë monstertempo's. Een van die nadele van BWS is dat hulle slegs binnenshuis gebruik kan word. Onlangse ontwikkelings in sensor tegnologie het egter gelei na die beskikbaarheid van traagheids-BWS-tegnologie (TBT). TBT gebruik traagheidsmetingseenhede (TMEs) wat aan 'n persoon se liggaam aangeheg kan word om die kinematika te verkry sonder enige eksterne sensore. TBT is dus volkome draagbaar, wat nuwe geleenthede skep vir kliniese bewingsanalises. Hierdie projek evalueer die gebruik van TBT vir die verbetering van fietsry kinematika. Tien kompeterende fietsryers (manlik) was getoets met 'n TBT terwyl hulle teen 2, 3.5 and 5.5 W.kg-1 gery het op 'n pad, en op 'n stilstaande oefenfietsraam. 'n Maatstaftoets was ook uitgevoer waar fietsry-kinematika gelyktydig met die TBT en die Vicon optiese BWS opgeneem was. Die eerste doel van die navorsing was om die moontlikheid te ondersoek of fietsryer kinematika op die pad gemeet kan word. Die resultate toon dat die ferro-magnetiese materiale wat in meeste padfietse voorkom, 'n beduidende magnetiese steuring (tot 50% afwyking in intensiteit) op die TMEs naby die pedale en handvatsels veroorsaak, wat lei tot aansienlike foute in die kinematiese metings. Gevolglik was dit gevind dat die TBT nie volle-liggaam kinematika op 'n fiets kan meet nie. Nogtans, het die resultate van die Vicon maatstaftoets bewys dat die TBT nog steeds akkurate heup (wortel van die gemiddelde kwadraad fout (WGKF) < 1°), knie (WGKF < 4°) en enkel (WGKF < 3°) fleksie kan meet met die “Kinematiese Koppeling” algoritme. Die tweede doel was om te bepaal of daar 'n beduidende verskil tussen die laboratorium en pad fietsry-kinematika is. Die buitelug fleksie data het beduidend verskil van die binnenshuise resultate, veral vir minimum fleksie (P < 0.05 vir alle gewrigte). Veranderinge in fietsryer kinematika tussen hoë en lae krag het ook beduidend meer variasie op die pad (R2 = 0.36, 0.61, 0.08) as op die oefenfietsraam (R2 = 0.93, 0.89, 0.56) vir die heup, knie en enkel gewrigte, onderskeidelik, gehad. Hierdie resultate bevraagteken die ekologiese geldigheid van kinematiese toetse op fietsryers in 'n laboratorium. 'n Laaste doel was om die toepassings van TBT vir die optimering van fietsry kinematika te ondersoek. 'n Verskeidenheid aspekte van die analise en verbetering van fietsry kinematika met die TBT word bespreek. Die gevolgtrekking is dat TBT geskik is vir gebruik as 'n dinamiese instrument vir die analise van biomeganiese doetreffendheid, bilaterale asimmetrie en die voorkoming van beserings. Aanbevelings vir toekomstige werk, sluit in die uitskakeling van die magnetiese inmenging, asook die integrasie van die TBT data met kinetiese metings.

This work will give a wide survey for various techniques that are present in the field of character computer animation, which concentrates particularly on those techniques and problems involved in the production of realistic character synthesis and motion. A preliminary user study (including Questionnaire, online publishing such as flicker.com, interview, multiple choice questions, publishing on Android mobile phone, and questionnaire analysis, validation, statistical evaluation, design steps and Character Animation Observation) was conducted to explore design questions, identify users' needs, and obtain a "true story" of quality character animation and the effect of using animation as useful tools in Education. The first set of questionnaires were designed to accommodate the evaluation of animation from candidates from different walks of life, ranging from animators, gamers, teacher assistances (TA), students, teaches, professionals and researchers using and evaluating pre-prepared animated character videos scenarios, and the study outcomes has reviewed the recent advances techniques of character animation, motion editing that enable the control of complex animations by interactively blending, improving and tuning artificial or captured motions. The goal of this work was to augment the students learning intuition by providing ways to make education and learning more interesting, useful and fun objectively, in order to improve students’ respond and understanding to any subject area through the use of animation also by producing the required high quality motion, reaction, interaction and story board to viewers of the motion. We present a variety of different evaluation to the motion quality by measuring user sensitivity, observations to any noticeable artefact, usability, usefulness etc. to derive clear useful guidelines from the results, and discuss several interesting systematic trends we have uncovered in the experimental data. We also present an efficient technique for evaluating the capability of animation influence on education to fulfil the requirements of a given scenario, along with the advantages and the effect on those deficiencies of some methods commonly used to improve animation quality to serve the learning process. Finally, we propose a wide range of extensions and statistical calculation enabled by these evaluation tools, such as Wilcoxon, F-test, T-test, Wondershare Quiz creator (WQC), Chi square and many others explained with full details.

Durant cette thèse, nous nous sommes intéressés à la problématique de la captation de mouvement sans marqueurs. Une approche classique est basée sur l'utilisation d'un modèle prédéfini du sujet, et est divisée en deux phases : celle d'initialisation, où la pose initiale du sujet est estimée, et celle de suivi, où la pose actuelle du sujet est estimée à partir des précédentes. Souvent, la phase d'initialisation est faite manuellement, rendant impossible l'utilisation en direct, ou nécessite des actions spécifiques du sujet. Nous proposons une phase d'initialisation automatique et temps-réel, utilisant l'information topologique extraite par squelettisation d'une reconstruction 3D du sujet. Cette information est représentée sous forme d'arbre (arbre de données), qui est mis en correspondance avec un arbre utilisé comme modèle, afin d'identifier les différentes parties du sujet. Pour obtenir une telle méthode, nous apportons des contributions dans les domaines de la topologie discrète et de la théorie des graphes. Comme notre méthode requiert le temps réel, nous nous intéressons d'abord à l'optimisation du temps de calcul des méthodes de squelettisation, ainsi qu'à l'élaboration de nouveaux algorithmes rapides fournissant de bons résultats. Nous nous intéressons ensuite à la définition d'une mise en correspondance efficace entre l'arbre de données et celui décrivant le modèle. Enfin, nous améliorons la robustesse de notre méthode en ajoutant des contraintes novatrices au modèle. Nous terminons par l'application de notre méthode sur différents jeux de données, démontrantses propriétés : rapidité robustesse et adaptabilité à différents types de sujet / This manuscript deals with the problem of markerless motion capture. An approach to thisproblem is model-based and is divided into two steps : an initialization step in which the initialpose is estimated, and a tracking which computes the current pose of the subject using infor-mation of previous ones. Classically, the initialization step is done manually, for bidding the possibility to be used online, or requires constraining actions of the subject. We propose an automatic real-time markerless initialization step, that relies on topological information provided by skeletonization of a 3D reconstruction of the subject. This topological information is then represented as a tree, which is matched with another tree used as modeldescription, in order to identify the different parts of the subject. In order to provide such a method, we propose some contributions in both digital topology and graph theory researchfields. As our method requires real-time computation, we first focus on the speed optimization of skeletonization methods, and on the design of new fast skeletonization schemes providing good results. In order to efficiently match the tree representing the topological information with the tree describing the model, we propose new matching definitions and associated algorithms. Finally, we study how to improve the robustness of our method by the use of innovative con-straints in the model. This manuscript ends by a study of the application of our method on several data sets, demon-strating its interesting properties : fast computation, robustness, and adaptability to any kindof subjects

In order to simulate virtual humans more realistically and enable them life-like behaviours, several exploration research on emotion calculation, synthetic perception, and decision making process have been discussed. A series of sub-modules have been designed and simulation results have been presented with discussion. A visual based synthetic perception system has been proposed in this thesis, which allows virtual humans to detect the surrounding virtual environment through a collision-based synthetic vision system. It enables autonomous virtual humans to change their emotion states according to stimuli in real time. The synthetic perception system also allows virtual humans to remember limited information within their own First-in-first-out short-term virtual memory. The new emotion generation method includes a novel hierarchical emotion structure and a group of emotion calculation equations, which enables virtual humans to perform emotionally in real-time according to their internal and external factors. Emotion calculation equations used in this research were derived from psychologic emotion measurements. Virtual humans can utilise the information in virtual memory and emotion calculation equations to generate their own numerical emotion states within the hierarchical emotion structure. Those emotion states are important internal references for virtual humans to adopt appropriate behaviours and also key cues for their decision making. The work introduces a dynamic emotional motion database structure for virtual human modelling. When developing realistic virtual human behaviours, lots of subjects were motion-captured whilst performing emotional motions with or without intent. The captured motions were endowed to virtual characters and implemented in different virtual scenarios to help evoke and verify design ideas, possible consequences of simulation (such as fire evacuation). This work also introduced simple heuristics theory into decision making process in order to make the virtual human’s decision making more like real human. Emotion values are proposed as a group of the key cues for decision making under the simple heuristic structures. A data interface which connects the emotion calculation and the decision making structure together has also been designed for the simulation system.

Le but de cette thèse a été de redéfinir le diagnostic d’hyperlaxité de l’épaule. Ce travail s’appui sur plusieurs études cliniques, chirurgicales et d’analyse du mouvement. Pour mener ce travail, nous avons tout d’abord défini l’hyperlaxité telle qu’elle est actuellement décrite dans la littérature, ainsi que ses liens avec l’instabilité de l’épaule et son traitement. Ce premier chapitre décrit également les moyens techniques d’analyse du mouvement qui seront utilisés dans cette thèse. Ensuite, plusieurs études ont été proposées. L’étude 2 est une étude chirurgicale, qui a cherché à corréler la laxité capsulaire étudiée en per opératoire et l’hyperlaxité clinique. L’étude 3 a ensuite rechercher les moyens de rendre plus reproductible la mesure de la rotation externe dans le cadre de l’hyperlaxité. Les études 4 et 5 sont des études utilisant l’analyse du mouvement. La première a cherché à fiabiliser la mesure clinique des amplitudes articulaires de l’épaule en tentant d’analyser les facteurs d’erreur de mesure. La deuxième étude a ensuite eut pour but de définir le volume articulaire global du complexe articulaire de l’épaule et de préciser la relation de ce volume avec les différents degrés de liberté de l’épaule. Une dernière étude (Etude 6) a enfin permis de corréler le volume articulaire de l’épaule et les signes cliniques d’hyperlaxité. Enfin, le chapitre « conclusions générales et perspectives » rassemble les éléments de conclusion de ces différents travaux et a pour ambition de redéfinir le diagnostic d’hyperlaxité de l’épaule. Ce chapitre ouvre plusieurs perspectives. La première est de proposer des modifications de l’examen clinique de l’épaule et notamment pour le diagnostic d’hyperlaxité. La seconde est d’utiliser la description volumétrique de l’épaule dans d’autres situations physiologiques ou pathologiques. Enfin, nous rapportons les résultats préliminaires d’une étude anatomique visant à identifier la place respective de chaque articulation dans cette définition volumétrique des amplitudes articulaires de l’épaule. / The aim of this study was to give a new definition to shoulder hyperlaxity. This work was conduced with clinical, surgical andmotion capture experimentations. We first gave a definition of hyperlaxity, as described actually in the literature, and its link with shoulder instability and treatment. Chapter 1 described also motion capture technics used along this work. Then, several studies were proposed. Study n°2 was a surgical one, and tempted to correlate peroperative capsular laxity and hyperlaxity. Therafter, study n°3 looked for an optimized way to examine external rotation of the shoulder. Studies N° 4 and 5 used motion capture analysis to assess clinical shoulder examination patterns and global reachable shoulder space volume. This volume was finally correlated to shoulder sign of hyperlaxity in study n°6. The last chapter, « general conclusions and perspectives » gather together conclusions of each study and redefine hyperlaxity. Finally, we report our prospect, giving first results of an anatomical study exploring the volumetric definition of shoulder range of motion described previously