Analysis of the disturbance rejection ability of a passive dynamic walker with hip spring

In numerous passive dynamic walking experiments, we found a spring added between walker's two legs increase its walking success rate dramatically. To explore the inherent nature of this phenomenon, we make a simulation comparison between the method to add hip springs and the method to change leg mass center position and foot radius, on the extent how much walking disturbance rejection ability can be improved. We find that the hip springs placed between leg's center of mass have an enlarged basin of attraction of the walking cycle as well as a strengthened walking ability on irregular slope. Further, parameters study is performed by simulating the influence of hip spring, mass distribution and foot radius on the walker's disturbance rejection ability. The results show that hip springs can increase the walker's disturbance rejection ability while keeping the existence of stable equilibrium state unchanged, and arc foot can only obtain the same performance when the radius ia large, and the mass center position has little contribution to the disturbance rejection ability.