1,086 research outputs found
Predictive model of the human muscle fatigue: application to repetitive push-pull tasks with light external load
Repetitive tasks in industrial works may contribute to health problems among
operators, such as musculo-skeletal disorders, in part due to insufficient
control of muscle fatigue. In this paper, a predictive model of fatigue is
proposed for repetitive push/pull operations. Assumptions generally accepted in
the literature are first explicitly set in this framework. Then, an earlier
static fatigue model is recalled and extended to quasi-static situations.
Specifically, the maximal torque that can be generated at a joint is not
considered as constant, but instead varies over time accordingly to the
operator's changing posture. The fatigue model is implemented with this new
consideration and evaluated in a simulation of push/pull operation. Reference
to this paper should be made as follows: Sakka, S., Chablat, D., Ma, R. and
Bennis, F. (2015) 'Predictive model of the human muscle fatigue: application to
repetitive push-pull tasks with light external load', Int
Framework for Dynamic Evaluation of Muscle Fatigue in Manual Handling Work
Muscle fatigue is defined as the point at which the muscle is no longer able
to sustain the required force or work output level. The overexertion of muscle
force and muscle fatigue can induce acute pain and chronic pain in human body.
When muscle fatigue is accumulated, the functional disability can be resulted
as musculoskeletal disorders (MSD). There are several posture exposure analysis
methods useful for rating the MSD risks, but they are mainly based on static
postures. Even in some fatigue evaluation methods, muscle fatigue evaluation is
only available for static postures, but not suitable for dynamic working
process. Meanwhile, some existing muscle fatigue models based on physiological
models cannot be easily used in industrial ergonomic evaluations. The external
dynamic load is definitely the most important factor resulting muscle fatigue,
thus we propose a new fatigue model under a framework for evaluating fatigue in
dynamic working processes. Under this framework, virtual reality system is
taken to generate virtual working environment, which can be interacted with the
work with haptic interfaces and optical motion capture system. The motion
information and load information are collected and further processed to
evaluate the overall work load of the worker based on dynamic muscle fatigue
models and other work evaluation criterions and to give new information to
characterize the penibility of the task in design process.Comment: International Conference On Industrial Technology, Chengdu : Chine
(2008
Can virtual reality predict body part discomfort and performance of people in realistic world for assembling tasks?
This paper presents our work on relationship of evaluation results between
virtual environment (VE) and realistic environment (RE) for assembling tasks.
Evaluation results consist of subjective results (BPD and RPE) and objective
results (posture and physical performance). Same tasks were performed with same
experimental configurations and evaluation results were measured in RE and VE
respectively. Then these evaluation results were compared. Slight difference of
posture between VE and RE was found but not great difference of effect on
people according to conventional ergonomics posture assessment method.
Correlation of BPD and performance results between VE and RE are found by
linear regression method. Moreover, results of BPD, physical performance, and
RPE in VE are higher than that in RE with significant difference. Furthermore,
these results indicates that subjects feel more discomfort and fatigue in VE
than RE because of additional effort required in VE
A novel approach for determining fatigue resistances of different muscle groups in static cases
In ergonomics and biomechanics, muscle fatigue models based on maximum
endurance time (MET) models are often used to integrate fatigue effect into
ergonomic and biomechanical application. However, due to the empirical
principle of those MET models, the disadvantages of this method are: 1) the MET
models cannot reveal the muscle physiology background very well; 2) there is no
general formation for those MET models to predict MET. In this paper, a
theoretical MET model is extended from a simple muscle fatigue model with
consideration of the external load and maximum voluntary contraction in passive
static exertion cases. The universal availability of the extended MET model is
analyzed in comparison to 24 existing empirical MET models. Using mathematical
regression method, 21 of the 24 MET models have intraclass correlations over
0.9, which means the extended MET model could replace the existing MET models
in a general and computationally efficient way. In addition, an important
parameter, fatigability (or fatigue resistance) of different muscle groups,
could be calculated via the mathematical regression approach. Its mean value
and its standard deviation are useful for predicting MET values of a given
population during static operations. The possible reasons influencing the
fatigue resistance were classified and discussed, and it is still a very
challenging work to find out the quantitative relationship between the fatigue
resistance and the influencing factors
A framework of motion capture system based human behaviours simulation for ergonomic analysis
International audienceWith the increasing of computer capabilities, Computer aided ergonomics (CAE) offers new possibilities to integrate conventional ergonomic knowledge and to develop new methods into the work design process. As mentioned in [1], different approaches have been developed to enhance the efficiency of the ergonomic evaluation. Ergonomic expert systems, ergonomic oriented information systems, numerical models of human, etc. have been implemented in numerical ergonomic software. Until now, there are ergonomic software tools available, such as Jack, Ergoman, Delmia Human, 3DSSPP, and Santos, etc. [2-4]. The main functions of these tools are posture analysis and posture prediction. In the visualization part, Jack and 3DSSPP produce results to visualize virtual human tasks in 3-dimensional, but without realistic physical properties. Nowadays, with the development of computer technology, the simulation of physical world is paid more attention. Physical engines [5] are used more and more in computer game (CG) field. The advantage of physical engine is the nature physical world environment simulation. The purpose of our research is to use the CG technology to create a virtual environment with physical properties for ergonomic analysis of virtual human
Using virtual human for an interactive customer-oriented constrained environment design
For industrial product design, it is very important to take into account
assembly/disassembly and maintenance operations during the conceptual and
prototype design stage. For these operations or other similar operations in a
constrained environment, trajectory planning is always a critical and difficult
issue for evaluating the design or for the users' convenience. In this paper, a
customer-oriented approach is proposed to partially solve ergonomic issues
encountered during the design stage of a constrained environment. A single
objective optimization based method is taken from the literature to generate
the trajectory in a constrained environment automatically. A motion capture
based method assists to guide the trajectory planning interactively if a local
minimum is encountered within the single objective optimization. At last, a
multi-objective evaluation method is proposed to evaluate the operations
generated by the algorith
A new approach to muscle fatigue evaluation for Push/Pull task
International audiencePushing/Pulling tasks is an important part of work in many industries. Usually, most researchers study the Push/Pull tasks by analyzing different posture conditions, force requirements, velocity factors, etc. However few studies have reported the effects of fatigue. Fatigue caused by physical loading is one of the main reasons responsible for MusculoSkeletal Disorders (MSD). In this paper, muscle groups of articulation is considered and from joint level a new approach is proposed for muscle fatigue evaluation in the arms Push/Pull operations. The objective of this work is to predict the muscle fatigue situation in the Push/Pull tasks in order to reduce the probability of MSD problems for workers. A case study is presented to use this new approach for analyzing arm fatigue in Pushing/Pulling
A Full-chain OpenSim Model and Its Application on Posture Analysis of an Overhead Drilling Task
International audienceBiomechanical motion simulation and kinectic analysis of human joints and muscles provide insights into Musculoskeletal disorders. OpenSim is an open-source platform that give easy access to biome-chanical analysis, especially of muscles. The biomechanical analysis in OpenSim is based on pre-defined human models. Among the dozens of models available right now, none covers the muscles and joints of all the body parts. In view of the fact that most human motions are systemic, the lack of a comprehensive model prohibits synthesized and systemat-ical biomechanical analysis. The aim of this research is to develop an OpenSim model which enables the full-chain dynamic analysis of tasks involving multi-bodies. The model is developed based on two existing models. It consists of 45 body segments, 424 muscles and 39 degrees of freedom. The model was then used to simulate an overhead drilling task. Six drilling postures are analyzed, and the estimated joint moments and muscle activations are compared
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