  In order to optimise the costs and time of design of the new products while
improving their quality, concurrent engineering is based on the digital model
of these products. However, in order to be able to avoid definitively physical
model without loss of information, new tools must be available. Especially, a
tool making it possible to check simply and quickly the maintainability of
complex mechanical sets using the numerical model is necessary. Since one
decade, the MCM team of IRCCyN works on the creation of tools for the
generation and the analysis of trajectories of virtual mannequins. The
simulation of human tasks can be carried out either by robot-like simulation or
by simulation by motion capture. This paper presents some results on the both
two methods. The first method is based on a multi-agent system and on a digital
mock-up technology, to assess an efficient path planner for a manikin or a
robot for access and visibility task taking into account ergonomic constraints
or joint limits. The human operator is integrated in the process optimisation
to contribute to a global perception of the environment. This operator
cooperates, in real-time, with several automatic local elementary agents. In
the second method, we worked with the CEA and EADS/CCR to solve the constraints
related to the evolution of human virtual in its environment on the basis of
data resulting from motion capture system. An approach using of the virtual
guides was developed to allow to the user the realization of precise trajectory
in absence of force feedback.
