Effect of rolling on running performance

The present work investigates the effect of rolling contact during stance phase in running by relating the variation of foot curvature radii to running efficiency, stability and forward speed. Both a conservative reduced-order running model and one with a simple motor and friction model are used to simulate running with a rolling foot. We find that having a larger foot radius implies smoother peak vertical ground reaction forces. Increased foot radius also yields, up to a point, a larger region of stable gaits for the conservative system, and more stable, fast, and efficient gaits for the actuated version. These results motivate the design of a new set of legs to test these findings on a dynamic running platform.