101 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
A Framework to Illustrate Kinematic Behavior of Mechanisms by Haptic Feedback
The kinematic properties of mechanisms are well known by the researchers and
teachers. The theory based on the study of Jacobian matrices allows us to
explain, for example, the singular configuration. However, in many cases, the
physical sense of such properties is difficult to explain to students. The aim
of this article is to use haptic feedback to render to the user the
signification of different kinematic indices. The framework uses a Phantom Omni
and a serial and parallel mechanism with two degrees of freedom. The
end-effector of both mechanisms can be moved either by classical mouse, or
Phantom Omni with or without feedback
Realistic Rendering of Kinetostatic Indices of Mechanisms
International audienceThe work presented in this paper is related to the use of a haptic device in an environment of robotic simulation. Such device introduces a new approach to feel and to understand the boundaries of the workspace of mechanisms as well as its kinetostatic properties. Indeed, these concepts are abstract and thus often difficult to understand for the end-users. To catch his attention, we propose to amplify the problems of the mechanisms in order to help him to take the good decisions
An Integrated Simulation System for Human Factors Study
It has been reported that virtual reality can be a useful tool for ergonomics
study. The proposed integrated simulation system aims at measuring operator's
performance in an interactive way for 2D control panel design. By incorporating
some sophisticated virtual reality hardware/software, the system allows natural
human-system and/or human-human interaction in a simulated virtual environment;
enables dynamic objective measurement of human performance; and evaluates the
quality of the system design in human factors perspective based on the
measurement. It can also be for operation training for some 2D control panels
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
2D multi-objective placement algorithm for free-form components
This article presents a generic method to solve 2D multi-objective placement
problem for free-form components. The proposed method is a relaxed placement
technique combined with an hybrid algorithm based on a genetic algorithm and a
separation algorithm. The genetic algorithm is used as a global optimizer and
is in charge of efficiently exploring the search space. The separation
algorithm is used to legalize solutions proposed by the global optimizer, so
that placement constraints are satisfied. A test case illustrates the
application of the proposed method. Extensions for solving the 3D problem are
given at the end of the article.Comment: ASME 2009 International Design Engineering Technical Conferences &
Computers and Information in Engineering Conference, San Diego : United
States (2009
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