Abstract
How humans solve the problem of motor redundancy is an open question. To gain insight into this process, we investigated the muscle synergies extracted from human subjects in a producing-force task to explore the method of human's hand force control. Focusing on coordination of agonist and antagonist muscles, we introduce the A-A ratio and A-A activity. We observed a high correlation estimation of the muscle synergies extracted by applying Principal Component Analysis (PCA) to A-A ratio dataset with the force-direction. On the other hand, the muscle synergies extracted by applying PCA to A-A activity dataset was observed a high correlation in the magnitude of the force. These result indicate humans control force-directions with A-A ratio and force strength with A-A activity.
