DYNAMICS OF UPRIGHT POSTURE ON AN ACTIVE BALANCE BOARD WITH TUNABLE TIME-DELAY AND STIFFNESS

Neurological disorders, a concussion, or aging can extend the time-delay in the human neuromuscular balance system; this time-delay increase has been shown [5] to be an important factor contributing to the loss of balance. However, commercial balance boards used to help improve individual's balance deficiencies do not utilize time-delay as a tunable parameter. In order to systematically study stiffness and time-delay induced instabilities in standing posture, we developed an active balance board system with controllable torsional board stiffness, as well as an added controllable feedback time-delay of the torsional board. Using this dynamical system we confirmed the presence of two distinct mechanisms of instability: insufficient stiffness leading to tipping posture and excessive time-delays leading to limit cycle oscillations. We expect that this active balance board will allow for the early identification of an increased fall-risk, especially for subjects with extended time-delays and could help provide insights into how the human postural system adapts to various environments.