Experimental Evaluation of Balance Prediction Models for Sit-to-Stand Movement in the Sagittal Plane

Figure 2

An example of the dynamic balance condition obtained through a simple inverted pendulum. The horizontal axis represents the posterior position of the CM, measured with respect to the toe and normalized to the subject’s foot length (thus the 0 and 1 represent the toe and heel position, resp.). The vertical axis represents the anterior velocity of the CM normalized to the subject’s height. The solid lines enclose the CM velocity-position conditions that allow recovering static balance (gray-shaded area), that is, the dynamic balance conditions. The broken line represents the most energy-efficient trajectory (zero external torque).