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Viewing 1 to 30 of 69
2005-06-14
Technical Paper
2005-01-2687
Natsuki Miyata, Makiko Kouchi, Masaaki Mochimaru, Katsuaki Kawachi, Tsuneya Kurihara
Characterization of the human hand motion necessary to manipulate hand-held equipment requires accurate capture and reconstruction of the arbitrary subject's hand motions with respect to the object. The present study used an individual link structure modeled from optical motion capture data to perform this task and compared the results against those obtained by medical imaging. Posture data was captured while grasping several cylinders, and the captured data were utilized to generate new postures to grasp cylinders of arbitrary diameter.
2005-06-14
Technical Paper
2005-01-2686
Kimberly Farrell, Timothy Marler, Karim Abdel-Malek
In the field of human modeling, there is an increasing demand for predicting human postures in real time. However, there has been minimal progress with methods that can incorporate multiple limbs with shared degrees of freedom (DOFs). This paper presents an optimization-based approach for predicting postures that involve dual-arm coordination with shared DOFs, and applies this method to a 30-DOF human model. Comparisons to motion capture data provide experimental validation for these examples. We show that this optimization-based approach allows dual-arm coordination with minimal computational cost. This new approach also easily extends to models with a higher number of DOFs and additional end-effectors.
2005-06-14
Technical Paper
2005-01-2685
Liming Zhao, Ying Liu, Norman I. Badler
Simulating human reach is still challenging when considering complex interactions with the environment. Standard approaches involve inverse kinematics (IK) methods and usually require a complete but exponential cost search in configuration space. In ergonomic applications, both “naturalness” and interactive performance are important. We describe a real-time, collision-free, sternum-rooted IK solution for an articulated human figure based on motion capture data, human strength models, and multi-joint coordination functions. Movement paths are discovered through spatial search in a partitioned workspace. The system generates natural collision-free reach motions in real-time. The resulting animations and statistics demonstrate the efficacy of this approach.
2005-06-14
Technical Paper
2005-01-2683
Katsuaki Kawachi, Kei Aoki, Masaaki Mochimaru, Makiko Kouchi
This paper proposes a method for visualizing and classifying the variation in the motions of a person when entering a passenger vehicle. Entering behaviors vary greatly between individuals, especially if the vehicle door is designed to have large clearance. The present study was conducted with the aim of supporting the design process of seats and front doors by visualizing possible variations of entering motions using a motion database, rather than calculating a single representative movement. The motion database is consist of different motions caused by various seats, and the motions are classified by mapping them into two-dimensional plane according to the similarities between them. A representative entering motion for a clustered motion strategy group is synthesized and visualized on the 2D distribution plane by interpolating existing motions in the database.
2005-06-14
Technical Paper
2005-01-2684
Mickaël Hetier, Xuguang Wang, Frederic Robache, Barbara Autuori, Hervè Morvan
This paper presents the first experiment managed within the framework of the regional French project ST2 (French acronym for Sciences and Technologies for Safety in Transports). This program aims to study human pre-crash behavior in order to improve the efficiency of passive safety protection systems. An experiment was carried out using a driving simulator of LAMIH for investigating drivers frontal pre-crash postural changes. A scenario of an unavoidable crash was designed. To increase the level of realism during the crash, a real impact was added between the windscreen and a foam rubber block in addition to a truck horn sound. Risk car driver postures just before a frontal crash have been determined. The results have shown that none of the subjects adopted the standardized driving position during the collision and 30% of the subjects adopted a position with the left hand placed in front of steering wheel which can be considered as a risk position.
2005-06-14
Technical Paper
2005-01-2681
David W. Wagner, Matthew P. Reed, Don B. Chaffin
For many industrial tasks (push, pull, lift, carry, etc.), restrictions on grip locations and visibility constrain the hand and head positions and help to define feasible postures. In contrast, foot locations are often minimally constrained and an ergonomics analyst can choose several different stances in selecting a posture to analyze. Also, because stance can be a critical determinant of a biomechanical assessment of the work posture, the lack of a valid method for placing the feet of a manikin with respect to the task compromises the accuracy of the analysis. To address this issue, foot locations and orientations were captured in a laboratory study of sagittal plane and asymmetric manual load transfers. A pilot study with four volunteers of varying anthropometry approached a load located on one of three shelves and transferred the load to one of six shelves.
2005-06-14
Technical Paper
2005-01-2682
Dominique Lestrelin, Jules Trasbot
The constraints applied to the design of cars and of other transportation systems imply space-restricted environments for their customers and/or manufacturing or maintenance workers. Consequently, some actions such as getting in and out of a car, or reaching the safety-belt, or loading/unloading the luggage compartment, can be difficult for some customers. For that reason, the designers need CAD-tools to be able to simulate not only the probable postures but the behaviour and movements of these persons, and to assess their discomfort in these situations, taking into account the suppleness- and force-capabilities of the real people, including senior citizens. Considering these needs, and not satisfied by the existing software and available databases, Renault built a proposal for a European Project called REAL MAN. This project started in the last quarter of 2001 and ended by mid-2004.
2005-06-14
Technical Paper
2005-01-2680
R. Timothy Marler, Salam Rahmatalla, Meagan Shanahan, Karim Abdel-Malek
Using multi-objective optimization, we develop a new human performance measure for direct optimizationbased posture prediction that incorporates three key factors associated with musculoskeletal discomfort: 1) the tendency to move different segments of the body sequentially, 2) the tendency to gravitate to a comfortable neutral position, and 3) the discomfort associated with moving while joints are near their respective limits. This performance measure operates in real-time and provides realistic postures. The results are viewed using Santos™, an advanced virtual human, and they are validated using motion-capture. This research lays groundwork for studying how and why humans move as they do.
2005-06-14
Technical Paper
2005-01-2679
John N. Howell, Robert L. Williams, Robert R. Conatser, Janet M. Burns, David C. Eland
The Virtual Haptic Back (VHB) is designed as an aid to teaching medical palpatory diagnosis. It uses two PHANToM 3.0 haptic interfaces (SensAble Technologies, Inc.), permitting palpation by force feedback with two fingers of a life-sized virtual human back. A graphics image of the back is displayed on a monitor a few inches behind the palpable back. Movement of back components, e.g., skin or underlying vertebrae, by exertion of palpatory force by the user is reflected graphically. Mechanical properties of the back, e.g., spring constants of the surface, are chosen based on feedback from physicians experienced in palpatory diagnosis. Although subjective evaluation of the VHB by 81 users over 2 years is positive, results have not yet shown students being trained in palpatory diagnosis to perform better than controls subjects. Results guide modifications of the haptic model itself and of the user tasks employed during testing.
2005-06-14
Technical Paper
2005-01-2677
Brendan Ryan, Jin Wang, Christine M. Haslegrave
The aim of the current study was to construct a model of a road rail vehicle in JACK and investigate the view of the articulating arm of the machine for human models of different stature in test conditions simulating a digging task and a lifting task. The JACK software was also used to determine the likely effects on operator comfort of postural adjustments which would be required to see different parts of the articulating arm. Modelling of the tasks using JACK has been a useful first step in identifying the limitations in the field of view for vehicle operators of different statures. The use of the view cones in JACK have been evaluated and the simulations have highlighted the potential for discomfort arising from postural adjustments which would be necessary in the tasks. Further research on operators' postures and visual strategies during real world digging and lifting tasks is now necessary.
2005-06-14
Technical Paper
2005-01-2678
Bastian Marx, Christian Amann, Murielle Verver
This study deals with the usability of the newly developed MADYMO human models for seat development. Three models consisting of FE-buttocks, SAE H-point mannequin and multi-body 50th percentile occupant model were used to predict the static and dynamic behavior of a man on a car seat, i.e. pressure distribution, H-Point position and behavior under vertical vibrations. Part of the investigation was also an FE seat model especially adapted to seating comfort referring to a medium-class BMW vehicle. On the same basis, hardware tests have been performed at BMW to compare the results with the simulation runs. As a result, it shows that it is possible to get usable seat pressure distributions and h-point values with the models, whereas an improvement of the foam model seems necessary to get reliable transmissibility data.
2005-06-14
Technical Paper
2005-01-2676
Xiaojiang Xu, Thomas L. Endrusick, William B. Santee, Margaret A. Kolka
Abstract A mathematical model utilizing the measured thermal resistance of footwear to predict toe temperature was developed. A lumped system represents the toe region as a single “toe” and a heat balance equation was established. The simulation was validated with measured physiological data obtained from human testing wearing the same footwear. The model prediction agreed with measured values within one standard deviation. The proposed approach, which consists of a heated thermal foot test and then modeling, is a cost effective alternative to human testing. The model has application for military planning, cold injury risk prediction and the selection of adequate protective footwear.
2005-06-14
Technical Paper
2005-01-2675
Matthew P. Reed, Kristy Satchell, Aris Nichols
The development of a new carrier route vehicle for the U.S. Postal Service began with the design of the vehicle interior from an operator-centered perspective. A task analysis of the postal worker while driving and while performing mail-handling operations guided the layout of the vehicle interior. The Jack™ human modeling software was used, along with SAE Recommended Practices and other tools, to create a vehicle environment that will accommodate a large percentage of the operator population. The challenges of designing for this unique work environment provided a good opportunity to evaluate the relative strengths and weaknesses of the available human factors tools, including the Jack™ digital human figure model. This paper describes the development of the vehicle interior, discusses some lessons learned, and concludes with recommendations for increased functionality and improved integration of vehicle interior design tools.
2005-06-14
Technical Paper
2005-01-2707
Wendy Pewinski, Amanda Esquivel, Jon Ruud, Missy Stefani, Ana Barbir
It is unknown how efficient Jack E-factory is in producing outputs that correlate with automotive seating applications. The purpose of this study was twofold. First, it was to assess how the judgment of the Jack operator when manikin positioning affects the Jack output. This was achieved by collecting clinic data where participants executed specific seat functions, comparing this information with existing Jack simulations, and repeating those simulations with observed posture changes, noting the difference in results. The second purpose was to develop a correlation between capability and acceptability. Jack E-factory generates data on the percentage of a population capable of performing a certain task, but does not provide any insight as to whether the task is acceptable to these people. Therefore, data on human acceptability of the same tasks were also collected. The results showed that Jack outputs are sensitive to the positioning of the manikin within its environment.
2005-06-14
Technical Paper
2005-01-2706
Fabien Dufour, Xuguang Wang
Both motion simulation and discomfort evaluation are needed for a design engineer when using a digital human model. Thanks to recent progress on motion capture and motion modeling, simulating complex motions in industrial application oriented becomes possible. However, how to evaluate the discomfort associated with such complex motions is another challenge for digital human modeling researchers. In collaboration with French car makers, we have investigated the issue of how to build generic predictive discomfort models of highly environment-constrained motions such as car ingress/egress motions. The purpose of this paper is to present a novel concept called ‘neutral movement’ and to show how it can be used for discomfort modeling of environment-constrained motions. In this paper, the discomfort of car ingress/egress movements will be analyzed with help of the concept of neutral movement. The advantages and limitations of the proposed discomfort modeling approach will also be discussed.
2005-06-14
Technical Paper
2005-01-2704
Gerri E. Archer, Michael Kolich
Digital human models have greatly enhanced design for the automotive driving environment. The major advantage of the models today is their ability to quickly test a broad range of the population within specific design parameters. The need to create expensive prototypes and run time consuming clinics can be significantly reduced. However, while the anthropometric databases within these models are comprehensive, the ability to position the manikins in a driving posture is limited. This study collected driving postures for occupants in two vehicle packages, a passenger car and utility-type vehicle. In all instances the occupant was instructed to adjust the vehicle parameters so they were in their most comfortable position. The posture of the occupants was then compared to postural output from RAMSIS and Catia V5 HumanBuilder.
2005-06-14
Technical Paper
2005-01-2710
Hyung Joo Kim, Emily Horn, Jasbir S. Arora, Karim Abdel- Malek
New methods for fast, adaptive motion prediction of a virtual human are proposed and tested. An optimal locomotion for gait-driven motions like pushing, climbing and pick-up/delivery are sought through gradient-based optimization and inverse-dynamics. Such gait-driven motion can be produced by adapting the normal gait motion to the case when a characteristic force is applied, which is called an applied force. The applied force is a resistance force for pushing case and an object weight for delivery case. The concept of the zero moment point is modified to assess the dynamic equilibrium of the motion in presence of the applied force. For fast calculation, analytical forms of the cost/constraint gradients are provided. Stepping patterns are specified a priori to ensure the continuity of the cost/constraint function gradients. Also, by varying knots for the B-spline curve approximation, the gait stage durations are optimized.
2005-06-14
Technical Paper
2005-01-2705
Mark de Zee, John Rasmussen, Jeroen Lem, Karl Siebertz
This study concerns the biomechanical computer simulation of the Active Motion system for car seats. This system can impose different kinds of small motions on the pelvis of the driver. Muscle activities were estimated for different parameters for the Active Motion using a musculo-skeletal model in the AnyBody Modeling System. The simulations suggest that a person using the Active Motion will not receive additional loads caused by the feature. Further, the Active Motion system might generate an average relative tension relief within a cycle up to 60 %. This avoids long-term static load, which might postpone or reduce discomfort. The average relative tension relief is most sensitive to pitch and roll amplitudes.
2005-06-14
Technical Paper
2005-01-2711
M. M. Verver, A. M. Dalenoort, H. G. Mooi
The impact of comfort is becoming increasingly important. On one hand, manufacturers use comfort to distinguish their products from their competitors. On the other hand, more cars than ever are used professionally. The prolonged sitting in automotive conditions of professional drivers introduced new physical complaints, resulting in high social costs. However, the cause of these complaints is not well understood. The use of virtual testing tools can contribute to both speeding up and reducing the costs of the development process of new more comfortable cars and the research in the causes of the new complaints. Vibration loading has often been identified as a source of discomfort. In literature, several human models developed for prediction of human resonance behaviour in vibrations were described. In most of these human body models, the muscles are represented in a simplified way.
2005-06-14
Technical Paper
2005-01-2708
Adriana-Violeta Savescu, Laurence Cheze
Most research on the thumb kinematics has focused on the local trapezo-metacarpal movement independently of the hand. In the clinical area, these studies can be sufficient. However, when the simulation of the hand movement and prehensile tasks with numerical dummies is needed, the thumb has to be considered as an integral part of the hand so a study in this direction proves to be essential. The objective of the present study is to analyze the kinematics of the thumb in relation to the hand (i.e. from the wrist’s joint). This paper proposes a four-link kinematic model of the thumb with 5 degrees of freedom (DOF) for a better representation of the opposition of the thumb with the other fingers. The interphalangeal and the metacarpophalangeal joints of the thumb have 1 flexion/extension DOF each and the carpo-metacarpophalangeal has 3 DOF (flexion/extension, abduction/adduction and rotation).
2005-06-14
Technical Paper
2005-01-2709
Xianlian Zhou, Jia Lu
Biomechanical analysis of skeletal muscles is an important task in digital human systems. The standard finite element method (FEM) can be used for muscle analysis; however, a full-scale FEM model can be overly complicated in a digital human system. In this work, we describe an efficient method of muscle analysis. The method is a combination of the Non-Uniform Rational B-spline (NURBS) geometric representation and the Galerkin methods. The basic idea is to establish the discrete equations of motion on the basis of NURBS geometry directly, without resorting to additional meshing. The method can adequately model muscle motion and stress while keeping the model size and complexity at a tractable level. As the first step towards interactive stress analysis in a digital human, we have developed NURBS FEM model for isolated muscles in human upper limb.
2005-06-14
Technical Paper
2005-01-2714
Hans Druyts, Wim De Craecker, Herman Ramon, Bart Haex, Esmeralda Forausbergher
It is generally recognized that long-term whole-body vibrations can induce degeneration of the lumbar spine, but it remains unclear what the exact mechanism behind this degeneration is. The problem is complex due to the incompletely understood dynamic responses of the body and influence of many variables. Several researchers have indicated the importance of the rocking movement of the pelvis in the response of the spinal system, but only few data is available to support this hypothesis. A 3D finite element (FE) model of the human buttocks is developed. The model contains a detailed geometric description of the pelvis and thighs and realistic material properties, seated on a rigid chair. The model’s response was verified with the chair moving according to a multisine signal comprising frequencies from 0.7 to 20Hz. The model reveals considerable pelvic rotation during the vibration.
2005-06-14
Technical Paper
2005-01-2715
W. De Craecker, H. Druyts, H. Ramon, E. Forausbergher, B. Haex, R. Van Audekercke, P. Coorevits, G. Vanderstraeten
Low back pain presents a common problem in occupational health, where exposure to vibration in vehicles is recognised as an important risk factor. It is commonly accepted that long-term exposure to whole-body vibrations can induce degenerative changes in the lumbar spine, but it is not understood what injury mechanisms are responsible for the problems involved. The standard approach is to model and to measure spine movement in response to low frequency vibrations (in the range of 0-20 Hz), in order to make a realistic prediction of vibration transmission through the human body, and of consequent pressure/tension between spine segments. This information, together with data on muscle behaviour, should produce an improved understanding of the spinal movements caused by vibration, and provide objective means for comfort and health evaluation of specific vibration frequencies and body postures.
2005-06-14
Technical Paper
2005-01-2713
X. George Zu
We have developed a digital human model, called VIP-Man, from segmented and labeled Visible Human (Male) image set containing about 100 radio-sensitive organs and tissues (selected from 1400 anatomical structures). The voxel size is 0.33mm × 0.33mm × 1.0 mm and the whole-body contains about 3.7 billion voxels. The VIP-Man model has been coupled with various Monte Carlo codes to simulate occupational and medical scenarios. More recently, a preliminary study has developed a 4D version of the VIP-Man model to account for the motions of the heart and lungs. This paper discusses the past experience and future issues to be addressed including the extension of the existing model into multi-scale testbeds for deformable organ geometry modeling, medical imaging, radiation treatment planning, and virtual surgical simulations.
2005-06-14
Technical Paper
2005-01-2712
M. A. Bhatti, Ray P.S. Han, Ryan Vignes
Since muscles act to translate an electrical impulse from the central nervous system into motion, it is essential to have a suitable mathematical model for muscles and groups of muscles for a virtual soldier environment. This paper presents a methodology in which the muscle contraction is broken down into three distinct physiological processes: calcium release and re-absorption by the sarcoplasmic reticulum, the rate at which calcium binds and unbinds to troponin, and the generation of force due to cross-bridge cycling and the elasticity of the muscle fibers. These processes have been successfully modeled by Ding and Wexler as a system of coupled differential and algebraic equations. These equations give the calcium-time history and the force time history of the muscle. By varying the electrical stimulation rates, the muscles can produce forces of varying magnitude and duration over which the force can be maintained.
2005-06-14
Technical Paper
2005-01-2718
Sameer S. Patwardhan, C. L. Bloebaum, V. N. Krovi
Computer Aided Ergonomic Design Systems (CAEDS) currently lack the ability of generating human models based on a user-entered database. Additionally, recent studies have not focused on the ability to reverse engineer the anthropometric dimensions that can be suited for a final design. This paper presents a toolbox based on developed methodologies that use human models to specify the interior dimensions of a passenger car. It also allows a designer to create these human models using a database of their choice. The designer can also reverse engineer a population based on the final design, and test any population to find its accommodation range. There are three modules in the toolbox - Human Model Generation, Occupant Driver Packaging, and Reverse Engineering.
2005-06-14
Technical Paper
2005-01-2719
Karl D. Reinig, Christian Lee, David Rubinstein, Michelle Bagur, Libby Prince, Victor Spitzer
The National Library of Medicine’s Visible Human Project began with a contract to cryosection and photograph one male and one female cadaver. The University of Colorado’s Center for Human Simulation (CHS) performed the research and supplied the raw images, which have been freely distributed since. However, the steps required to create models suitable for studying and displaying trauma dwarf the creation of the original images. Over the past ten years, the CHS has spent approximately 20 people years segmenting and classifying the data. This process creates a number for each volume element (voxel) that identifies the structure to which it belongs and becomes the major driver of the database of associated properties. Creating polygons from this data differs from the creation of polygons from fuzzy data such as Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) and has led us to develop our own polygon creation methods as well.
2005-06-14
Technical Paper
2005-01-2716
E. de Rochefort, M. M. Verver, A. Grunendahl, H. G. Mooi, C. Butenweg
Comfort of car seats is becoming an increasingly important issue in the design of vehicles for professional use as well as for personal use. People using cars professionally, like drivers of taxis, trucks, and busses, often have to drive for prolonged periods sometimes leading to physical complaints, like e.g. low back pain. Apart from experimental investigations, virtual testing is becoming more important to get more insight in the problem of low back pain. This paper presents a finite element (FE) model of the lumbar spine (L1-L5). The model contains a detailed geometric description of the lumbar spine and realistic material properties. On a segmental level and as a whole, the model's response was verified for quasi-static and dynamic conditions based on experimental data published in literature. The quasi-static segmental validation comprised of compression, posterior, anterior and lateral shear, flexion and extension, lateral bending and axial torque.
2005-06-14
Technical Paper
2005-01-2717
Joo H. Kim, Karim Abdel-Malek, Jingzhou Yang, Kimberly Farrell, Kyle Nebel
This paper presents an optimization-based algorithm for simulating the dynamic motion of a digital human. We also formulate the metabolic energy expenditure during the motion, which is calculated within our algorithm. This algorithm is implemented and applied to Santos™, an avatar developed at The University of Iowa. Santos™ is a part of a virtual environment for conducting digital human analysis consisting of posture prediction, motion prediction, and physiology studies. This paper demonstrates our dynamic motion algorithm within the Santos™ virtual environment. Mathematical evaluations of human performance are essential to any effort to compare various ergonomic designs. In fact, the human factors design process can be formulated as an optimization problem that maximizes human performance. In particular, an optimal design must be found while taking into consideration the effects of different motions and hand loads corresponding to a number of tasks.
2005-06-14
Technical Paper
2005-01-2691
Q. Wang, Y.-J. Xiang, H.-J. Kim, J. S. Arora, K. Abdel-Malek
Simulating human motion is a complex problem due to redundancy of the human musculoskeletal system. The concept of task-based motion prediction using single- or multi-objective optimization techniques provides a viable approach for predicting intermediate motions of digital humans. It is shown that task-based motion prediction is in fact a numerical optimal control problem. Alternative formulations for simulation of human motion are possible and can be solved by modern nonlinear optimization methods. Three techniques based on state variable elimination, direct collocation and differential inclusion are presented and compared. The basic idea of the formulations is to treat different combinations of the state variables, such as the joint profiles and torques or their parametric representations as independent variables in the optimization process.
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