Generation of human standing-up motion with muscle synergies using forward dynamic simulation

The standing-up motion is one of the most important activities of daily livings. In order to understand the strategy to achieve the standing-up motion, muscle synergy analysis is applied to the measured data during human standing-up motion. In addition, musculoskeletal model which consists of three body segments and nine muscles in lower limb is developed to ensure that the standing-up motion can be generated by muscle synergies. As a result, three muscle synergies have been extracted from the human standing-up motion, and each synergy strongly corresponded to characteristic kinematic events: momentum flexion, momentum transfer, and posture stabilization. Results of forward dynamic simulation show that the standing-up motion can be achieved by controlling time-varying weighting coefficient of three muscle synergies instead of controlling individual nine muscles.