AUTHOR=Wochner Isabell , Driess Danny , Zimmermann Heiko , Haeufle Daniel F. B. , Toussaint Marc , Schmitt Syn TITLE=Optimality Principles in Human Point-to-Manifold Reaching Accounting for Muscle Dynamics JOURNAL=Frontiers in Computational Neuroscience VOLUME=14 YEAR=2020 URL=https://www.frontiersin.org/journals/computational-neuroscience/articles/10.3389/fncom.2020.00038 DOI=10.3389/fncom.2020.00038 ISSN=1662-5188 ABSTRACT=

Human arm movements are highly stereotypical under a large variety of experimental conditions. This is striking due to the high redundancy of the human musculoskeletal system, which in principle allows many possible trajectories toward a goal. Many researchers hypothesize that through evolution, learning, and adaption, the human system has developed optimal control strategies to select between these possibilities. Various optimality principles were proposed in the literature that reproduce human-like trajectories in certain conditions. However, these studies often focus on a single cost function and use simple torque-driven models of motion generation, which are not consistent with human muscle-actuated motion. The underlying structure of our human system, with the use of muscle dynamics in interaction with the control principles, might have a significant influence on what optimality principles best model human motion. To investigate this hypothesis, we consider a point-to-manifold reaching task that leaves the target underdetermined. Given hypothesized motion objectives, the control input is generated using Bayesian optimization, which is a machine learning based method that trades-off exploitation and exploration. Using numerical simulations with Hill-type muscles, we show that a combination of optimality principles best predicts human point-to-manifold reaching when accounting for the muscle dynamics.