A subject-specific software solution for the modeling and thevisualization of muscles deformations

Today, to create and to simulate a virtual anatomical version of a subject is useful in the decision process of surgical treatments. The muscular activity is one of the factors which can contribute to abnormal movements such as in spasticity or static contracture. In this paper, we propose a numerical solution, based on the Finite Element (FE) method, able to estimate muscles deformations during contraction. Organized around a finite element solver and a volumetric environment, this solution is made of all the modeling and simulation processes from the discretization of the studied domain to the visualization of the results. The choices of materials and properties of the FE model are also presented such as the hyperelasticity, the contention model based on inter-meshes neighboring nodes pairing, and the estimation of nodal forces based on the subject-specific muscular forces and action line

Virtual humans: thirty years of research, what next?

In this paper, we present research results and future challenges in creating realistic and believable Virtual Humans. To realize these modeling goals, real-time realistic representation is essential, but we also need interactive and perceptive Virtual Humans to populate the Virtual Worlds. Three levels of modeling should be considered to create these believable Virtual Humans: 1) realistic appearance modeling, 2) realistic, smooth and flexible motion modeling, and 3) realistic high-level behaviors modeling. At first, the issues of creating virtual humans with better skeleton and realistic deformable bodies are illustrated. To give a level of believable behavior, challenges are laid on generating on the fly flexible motion and complex behaviours of Virtual Humans inside their environments using a realistic perception of the environment. Interactivity and group behaviours are also important parameters to create believable Virtual Humans which have challenges in creating believable relationship between real and virtual humans based on emotion and personality, and simulating realistic and believable behaviors of groups and crowds. Finally, issues in generating realistic virtual clothed and haired people are presente

3D modeling of the human upper limb including the biomechanics of joints, muscles and soft tissues

The challenge in virtual human modeling is to achieve the representation of the main human characteristics with as much realism as possible. Such achievements would allow the simulation and/or analysis of many virtual situations involving humans. Simulation is especially useful to derive information from the models so as to predict and/or reproduce the behaviors that would be observed in real situations. Computer methods in visualization and simulation have thus great potential for advances in medicine. The processes of strength generation and motion coordination are some of these phenomena for which there is still much remaining to be understood. The human shoulder is also probably the articulation of the human body which deserves more than any other to be named "terra incognita". Investigations towards the biomechanical modeling and simulation of the human upper limb are therefore presented in this study. It includes thorough investigation into the musculoskeletal anatomy and biomechanics of the human upper limb, into the biomechanical constitutive modeling of muscles and soft tissues, and into the nonlinear continuum mechanics and numerical methods, especially the incremental finite element methods, necessary for their simulation. On this basis, a 3-D biomechanical musculoskeletal human upper limb model has been designed using the Visible Human Data provided by the U.S. National Library of Medicine, and applied to the dynamic musculoskeletal simulation of the human upper limb. This research has been achieved in the context of the EU ESPRIT Project CHARM, whose objective has been to develop a comprehensive human animation resource database and a set of software tools allowing the modeling of the human complex musculoskeletal system and the simulation of its dynamics, including the finite element simulation of soft tissue deformation and muscular contraction. An investigation towards the application of this knowledge for the realistic modeling and animation of the upper limb in computer animation is then presented. The anatomical and biomechanical modeling of the scapulo-thoracic constraint and the shoulder joint sinus cones are proposed and applied to the realistic animation, using inverse kinematics, of a virtual skeleton and an anatomic musculoskeletal body model

Ergonomic Simulation Revisited Using Parametric Virtual Humans in the Biomechanical Framework

The conventional CAD/CAM approach to design does not show the essential spatial relationships between user and product that are crucial for intuitive design analysis. As populations age and the home appliance market stagnates, Universal Design principles implemented with computerized virtual worlds become more important for meeting the ergonomic problems of heterogeneous populations that are increasingly difficult to adequately test with real-world subjects. Digital Human Modelling (DHM) is an emerging area that bridges computer-aided engineering design, human factors engineering and applied ergonomics. The most advanced forms of this technology are being used by many researchers for practical applications, including ergonomic analysis. However, a state of the art model of this technology has never been conceived for the conceptual design stage of a product development cycle as most conventional DHM techniques lack real time interaction, require considerable user intervention, and have inefficient control facilities and non-adequate validation techniques, all contributing to slow production pipelines. They have also not addressed the needs of the growing ageing population in many societies across the globe. The focus of this dissertation is to introduce a complete framework for ergonomic simulation at the conceptual design stage of a product development cycle based on parametric virtual humans in a prioritized inverse kinematics framework while taking biomechanical knowledge in to account. Using an intuitive control facility, design engineers can input a simple CAD model, design variables and human factors in to the system. The evaluation engine generates the required simulation in real-time by making use of an Anthropometric Database, Physical Characteristic Database and Prioritized Inverse Kinematics architecture. The key components of the total system are described and the results are demonstrated with a few applications such as kitchen, wash-basin and bath-tub. By introducing a quantitative estimation of ageing algorithm for anthropometric digital human models, products can be designed from the start to suit the ergonomic needs of the user rather than the biases and assumptions of the designer. Also, by creating a tool that can be used intuitively by non-specialists in a dynamic, real-time environment, designers can stop relying on specialists to test the safety of their ideas and start to effectively use data about populations to discover designs that can be used more easily by more people. Results have been validated with real human subjects indicating the practical implication of the total system as an ergonomic design tool for the conceptual design stage of a product development cycle

Chapter Towards a Realistic and Self-Contained Biomechanical Model of the Hand

Computer modelling & simulatio

Footwear bio-modelling: An industrial approach

There is a growing need within the footwear sector to customise the design of the last from which a specific footwear style is to be produced. This customisation is necessary for user comfort and health reasons, as the user needs to wear a suitable shoe. For this purpose, a relationship must be established between the user foot and the last with which the style will be made; up until now, no model has existed that integrates both elements. On the one hand, traditional customised footwear manufacturing techniques are based on purely artisanal procedures which make the process arduous and complex; on the other hand, geometric models proposed by different authors present the impossibility of implementing them in an industrial environment with limited resources for the acquisition of morphometric and structural data for the foot, apart from the fact that they do not prove to be sufficiently accurate given the non-similarity of the foot and last. In this paper, two interrelated geometric models are defined, the first, a bio-deformable foot model and the second, a deformable last model. The experiments completed show the goodness of the model, with it obtaining satisfactory results in terms of comfort, efficiency and precision, which make it viable for use in the sector

IISE Trans Occup Ergon Hum Factors

Digital human modeling (DHM) and simulation software has been identified as an effective tool for evaluating work tasks and design alternatives without requiring the expense of physical mock-ups and production trials. Despite recent commercial advancements and a broader availability of DHM platforms, the peer-reviewed scientific literature lacks sufficient demonstration of the application of DHM software within an occupational safety and health process for mitigating exposures to physical risk factors in a real work environment. We describe the implementation of a commercially-available DHM platform as a component of an occupational safety and health process in a manufacturing environment over the course of one year. Success stories, challenges, and practical recommendations are discussed.T42 OH008436/OH/NIOSH CDC HHS/United StatesT42OH008436/ACL HHS/United StatesU19 OH008868/OH/NIOSH CDC HHS/United StatesU19OH008868/ACL HHS/United States2019-10-16T00:00:00Z30984907PMC64559526766vault:3192

The Functional, Ecological, and Evolutionary Morphology of Sea Lampreys (Petromyzon marinus)

Lampreys (Petromyzontiformes) are jawless vertebrates with an evolutionary history lasting at least 360 million years and are often used in comparisons with jawed vertebrates because some of their morphological aspects, such as the segmented trunk musculature with curved myosepta and a non-mineralized skeleton fibrous skeleton, are thought to resemble the condition of early vertebrates before the evolution of jaws. Although earlier authors studied the morphology of the skeleto-muscular system of the trunk of lampreys, their studies are not detailed and complete enough to allow a functional and biomechanical analysis that is needed as a basis for modeling the mechanics of lamprey locomotion and for understanding the causal roles played by the anatomical structures within the trunk. Questions remain, such as what is the architecture of the trunk fibroskeleton, and how does it function with the musculature to bend the trunk? This dissertation studied the functional, ecological and evolutionary morphology of the trunk of Sea Lampreys (Petromyzon marinus) as well as its relevance in understanding the environmental history of landlocked lamprey populations. Functional morphology revealed that the fibroskeleton of the trunk is a self-supporting concatenated system of fibers, which creates a scaffold for the musculature and transmits forces to bend the trunk during swimming. Ecological morphology demonstrated the adaptive advantage of the fibroskeleton’s architecture, which enables the movements that are performed during migration and spawning and gives lampreys the capacity to colonize upstream realms. These results help explain the evolutionary morphology of lampreys, which likely originated in freshwater as algal feeders and evolved into parasites after going through an intermediary scavenging stage. When these insights are applied to the evolution of landlocked Sea Lampreys, it becomes evident that their entry into freshwater lakes occurred as soon as they were able to reach them and that populations likely became established in Lake Ontario, Lake Champlain, and the Finger Lakes thousands of years ago. This insight undermines the current status of landlocked Sea Lampreys as invasive species in these lakes and the case for their eradication. Hence, this dissertation provides a comprehensive and integrative analysis of lamprey biology from their anatomy to environmental policy