This paper deals with the decision mechanism analysis and the design of bip
edal trajectories, for the stepping motion. For that we have used biomechan
ical model of the human body and dynamic control scheme previously develope
d by Gorce.(1) We based our study on an experimental protocol, in order to
determine behavioural laws for the task execution. We have developed a bipe
d trajectory generation process, taking into account the biped height and t
he obstacle dimensions. Furthermore, we characterize the stepping motion fe
asibility by introducing a security notion, and we define an "Admissible co
ntrol Domain", which relies on the relative position of the biped to the ob
stacle and the obstacle dimensions. This domain definition has led us to de
fine the biped behavioural strategies facing an obstacle: the biped execute
s the task at an accurate "chosen distance", or stops or takes another way.
Experimentations have allowed to validate simulations results.