Section: New Results

Biomechanics for motion analysis-synthesis

Participants : Charles Pontonnier, Georges Dumont, Steve Tonneau, Franck Multon, Julien Pettré, Ana Lucia Cruz Ruiz, Antoine Muller.

Ana-Lucia Cruz-Ruiz has been recruited as a PhD student since november 2013. The goal of this thesis is to define and evaluate muscle-based controllers for avatar animation. We developed an original control approach to reduce the redudancy of the musculoskeletal system for motion synthesis, based on the muscle synergy theory. For this purpose we ran an experimental campaign of overhead throwing motions. We recorded the muscle activity of 10 muscles of the arm and the motion of the subjects. Thanks to a synergy extraction algorithm, we extracted a reduced set of activation signals corresponding to the so called muscle synergies and used them as an input in a forward dynamics pipeline . Thanks to a two stage optimization method, we adapted the model's muscle parameters and the synergy signals to be as close as possible of the recorded motion. The results are compelling and ask for further developments [9] , [24] .

We are also developing an analysis pipeline thanks to the work of Antoine Muller. This pipeline aims at using a modular and multiscale description of the human body to let users be able to analyse human motion. For now, the pipeline is able to assemble different biomechanical models in a convenient descriptive graph [15] , Calibrate those models thanks to experimental data [30] and run inverse dynamics to get joint torques from exeperimental motion capture data [14] .