Publication

Proprioception plays an important role in postural stability. Here, we developed a hypothesis that when we cannot use all sensory information, we maintain upright posture with high muscle stiffness. To validate the hypothesis, we needed to confirm another hypothesis that humans can keep standing with some stiffness levels compensating for the loss of visual and vestibular information. We expanded a neural controller for an unperturbed stance with feedforward and proprioceptive feedback mechanisms to simulate a perturbed stance. A musculoskeletal model with 70 muscles and 13 degrees of freedom was prepared as a human body. We succeeded in ensuring that the musculoskeletal model maintains an upright standing posture against support surface translations in 12 directions with one stiffness level. The responses of leg muscles in our simulations were consistent with those in the previous work. Moreover, the limitation, i.e., the inability of high level control of the neural controller could be explained using the responses of the trunk muscles.