19 research outputs found
Human Arm simulation for interactive constrained environment design
During the conceptual and prototype design stage of an industrial product, it
is crucial to take assembly/disassembly and maintenance operations in advance.
A well-designed system should enable relatively easy access of operating
manipulators in the constrained environment and reduce musculoskeletal disorder
risks for those manual handling operations. Trajectory planning comes up as an
important issue for those assembly and maintenance operations under a
constrained environment, since it determines the accessibility and the other
ergonomics issues, such as muscle effort and its related fatigue. In this
paper, a customer-oriented interactive approach is proposed to partially solve
ergonomic related issues encountered during the design stage under a
constrained system for the operator's convenience. Based on a single objective
optimization method, trajectory planning for different operators could be
generated automatically. Meanwhile, a motion capture based method assists the
operator to guide the trajectory planning interactively when either a local
minimum is encountered within the single objective optimization or the operator
prefers guiding the virtual human manually. Besides that, a physical engine is
integrated into this approach to provide physically realistic simulation in
real time manner, so that collision free path and related dynamic information
could be computed to determine further muscle fatigue and accessibility of a
product designComment: International Journal on Interactive Design and Manufacturing
(IJIDeM) (2012) 1-12. arXiv admin note: substantial text overlap with
arXiv:1012.432
Fatigue evaluation in maintenance and assembly operations by digital human simulation
Virtual human techniques have been used a lot in industrial design in order
to consider human factors and ergonomics as early as possible. The physical
status (the physical capacity of virtual human) has been mostly treated as
invariable in the current available human simulation tools, while indeed the
physical capacity varies along time in an operation and the change of the
physical capacity depends on the history of the work as well. Virtual Human
Status is proposed in this paper in order to assess the difficulty of manual
handling operations, especially from the physical perspective. The decrease of
the physical capacity before and after an operation is used as an index to
indicate the work difficulty. The reduction of physical strength is simulated
in a theoretical approach on the basis of a fatigue model in which fatigue
resistances of different muscle groups were regressed from 24 existing maximum
endurance time (MET) models. A framework based on digital human modeling
technique is established to realize the comparison of physical status. An
assembly case in airplane assembly is simulated and analyzed under the
framework. The endurance time and the decrease of the joint moment strengths
are simulated. The experimental result in simulated operations under laboratory
conditions confirms the feasibility of the theoretical approach
On the connectivity of manipulator free workspace
International audienceThis article presents a new topological characterization of the free workspace of manip-ulators moving among obstacles. The free workspace is the set of positions and orienta-tions that the end-effector of the manipulator can reach, according to the joint limits of each of its links, and taking into account the obstacles of the environment. A classification of new connectivity properties of the free workspace is proposed, corresponding to different types of motions (point-to-point motions, following of continuous trajectories) that the manipulator can perform in the Cartesian space. For each property, a necessary and sufficient condition is given, which permits verification of the connectivity of the whole free workspace and leads to all the connected subspaces in it. These properties have been implemented in a Robotics C.A.D. system using octree representation of spaces. Some applications are presented, which show that this work is of primary interest for preparing off-line tasks, and is a new contribution to the problem of robotic cell layout design
Design Product Development and Manufacturing
Proceedings of SPDS 199