18 research outputs found
Method for determining musculotendon parameters in subject-specific musculoskeletal models of children developed from MRI data
A Predicted Optimal Performance of the Yurchenko Layout Vault in Women’s Artistic Gymnastics
Energetic versus sthenic optimality criteria for gymnastic movement synthesis
Dynamic synthesis of human movements raises the question of the selection of a
suitable performance criterion able to generate proper dynamic behaviors. Two quite different
criteria are likely to be appropriate candidates: the minimum effort cost (or sthenic criterion)
and the minimum energy cost. The paper is aimed at clarifying the dynamic effects of
these two fundamental criteria when considering movements executed with liveliness as they
are in gymnastic. It is well known that the former cost generates movements with smooth
dynamics. A special attention is devoted to the latter. The optimal control theory shows
that minimizing the energy consumption results in actuating inputs of bang-off-bang type
producing momentum impulses. When achieving dynamic synthesis, this criterion makes
necessary to account for bounds set on driving torques. Moreover, when dealing with onesided
contacts, as in floor handstands, the unilaterality of contact forces must be explicitly
accounted for since it tends to be infringed by impulsive efforts.
Numerical simulations of these formal properties are carried out using a parametric optimization
technique, and considering the raising phase of floor handstands. It is shown that
the energetic criterion tends to generate movements which exhibit similarities with their
real counterpart performed by an expert gymnast. Conversely, the sthenic criterion produces
movements quite different. But, a salient fact is that these ones proved to be easier to perform
by young beginners. As a result, they could help to coach novice gymnasts