Energy transformations in human movement by contact.

This study focuses on the transformation of energy in multilinkage systems by a deliberate use of the contact with the ground, leading to a derivation of the directional change of translational velocity of the body's center of mass. The coefficient of friction on the surface on which the impact occurs, and its effect on the overall movement, is studied for general multilinkage systems undergoing impact. The effect of surface friction is made apparent via simulation studies for a two-link example, where two interesting conditions arise: slippage or no slippage on the surface at impact. It is found that once the system stops on the surface, the translational energy increases as the angular velocity increases. Likewise, it is seen that the rotational energy after impact increases as the angular velocity of the first link increases, but the rate of increase of energy is less in the case where the system stops on the ground with no slippage.