Figure 5.

Effect of a uni-articular hip spring on gait. (a) Hip springs produce slightly faster steps, as the stance and swing leg both move faster (parameter: $\hat{P}=0.075$). (b) Dimensionless gait parameters as a function of hip spring stiffness. Limit cycles only exist for a narrow range of stiffnesses. Within this range, the hip spring causes shorter step lengths and higher step frequencies, with a minimal effect on walking speed. (c) Contour plot of walking speed as a function of hip spring stiffness and push-off impulse shows that the spring reduces the range of achievable gaits. Increasing stiffness leads to step failures either owing to WP or stumbling (ST).