The optimization of spring stiffness for passive dynamic walker

On a passive dynamic walker, we find that an appropriate spring placed on the mass center of two legs can greatly improve the walker´s walking performance, which includes its walking speed, disturbance rejection ability and step length. However, the extent to which spring influences these properties is unknown and how to choose an appropriate spring stiffness to achieve optimal walking performance still needs to be discussed. In this paper, we present a study on the effect of spring on these properties by constructing a synthesize index P to assess the walking performance. Through numerical simulation on three models, we find the walker with spring has a better walking performance over a pure passive dynamic walker and the extension spring on the mass center of two legs can improve a walker´s overall walking performance much better.