Abstract
Balance control is generally analyzed by applying the Inverted Pendulum model. According to this model, humans control joint torque and hold the vertical projection of Center of Mass (COM) in the area within which Center of Pressure (COP) can move. That is to say, COM is held within the Base of support. This study analyzed tip toe movement dividing body into ankle segment and upper body segment above the ankle by applying two-dimension in sagittal plane to show that humans can maintain balance even if COM drifts outside the base of support. The results revealed that the subject could produced the large deviation of angular momentum of the body around the COM without moving the COP. This deviation increased the distance between line of action of ground reaction force and COM to maintain balance. The direction of ground reaction force was the reverse of the direction of the fall. For this reason, the subject was able to maintain the balance with the force.
