Section: New Results
Biomechanics for motion analysis-synthesis
Participants : Charles Pontonnier [contact] , Georges Dumont, Franck Multon, Antoine Muller, Pierre Puchaud.
Based on a former PhD thesis (of Antoine Muller), we aim at democratizing the use of musculoskeletal analysis for a wide range of users. We proposed contributions enabling better performances of such analyses and preserving accuracy, as well as contributions enabling an easy subject-specific model calibration , . In order to control the whole analysis process, we propose a global approach of all the analysis steps: kinematics, dynamics and muscle forces estimation. For all of these steps, quick analysis methods have been proposed. Particularly, a quick muscle force sharing problem resolution method  has been proposed, based on interpolated data and improvements have been proposed . Moreover, the Music Toolbox is now proposed as an opensource software.
The determination of maximal torque envelopes method that we defined for the elbow torque analysis have been used for the shoulder . It is important, in order to calibrate muscular models, to be able to identify force parameters in a musculoskeletal.
Interactions between walkers
Participants : Anne-Hélène Olivier [contact] , Armel Crétual, Richard Kulpa, Sean Lynch.
Interaction between people, and especially local interaction between walkers, is a main research topic of MimeTIC. We propose experimental approaches using both real and virtual environments to study both perception and action aspects of the interaction. In the context of Sean Lynch's PhD, which was defended in October 2018 , we aimed at manipulating the nature of the visual information available to the participants to understand which information about the other walker are important to avoid a collision. We presented at IEEE VR 2018, our work on the influence of global and local information appearances  as well as on the influence of mutual gaze in the interaction .
We also provide lot of efforts to investigate, in collaboration with Julien Pettré from Inria Rainbow team, the process involved in the selection of interactions within our neighbourhood. Considering the complex case of multiple interactions, we first performed experiments in real conditions where a participant walked across a room whilst either one (i.e., pairwise) or two (i.e., group) participants crossed the room perpendicularly. By comparing these pairwise and group interactions, we assessed whether a participant avoids two upcoming collisions simultaneously, or as sequential pairwise interactions. Results showed that pedestrians are able to interact with two other walkers simultaneously, rather than treating each interaction in sequence. These results are currently in press in Frontiers in Psychology . Second, we performed experiments involving 40 people to understand how collective behaviour emerges . Third, in virtual conditions, we also coupled the analysis of gaze behaviour and the trajectory and showed that human gaze, during navigation, is attracted by other walkers presenting the higher risk of future collision , .
Finally, we continue working on the applications of studying human behaviour for application in human-moving robot interactions. The development of Robotics accelerated these recent years, it is clear that robots and humans will share the same environment in a near future. In this context, understanding local interactions between humans and robots during locomotion tasks is important to steer robots among humans in a safe manner. In collaboration with Philippe Souères and Christian Vassallo (LAAS, Toulouse), our work analyzed the behavior of human walkers crossing the trajectory of a mobile robot that was programmed to reproduce this human avoidance strategy. In contrast with a previous study, which showed that humans mostly prefer to give the way to a non-reactive robot, we observed similar behaviors between human-human avoidance and human-robot avoidance when the robot replicates the human interaction rules. This result highlight the importance of controlling robots in a human-like way in order to ease their cohabitation with humans . In collaboration with Jose Grimaldo da Silva and Thierry Fraichard (Inria Grenoble), we designed a shared-effort model during interaction between a moving robot and a human relying on walker-walker collision avoidance data .
Biomechanical analysis of tennis serve
Participants : Richard Kulpa [contact] , Benoit Bideau, Pierre Touzard.
In the context of the exclusive collaboration with the FFT (French Tennis Federation), we made new experiments on top-level young French players (between 12 up to 18 years old) to quantify the relation between motor technical errors and their impact on the risk of injury. We thus concurrently captured the kinematics of their tennis serve and the muscular activities of the upper-body. We recently validated that the Waiter's serve implies higher risk of injuries . It is a movement that was know by the coaches as not productive and risky but it was never validated. Moreover, we evaluated the strategies of pacing use during five-set matches in the top tennis tournaments .