Fig. 6

Nut and spring length change:length change of the nut (dotted) and the spring (dashed) for the mean of multiple strides using the Walk-Run ankle (red) and the mean of up to 21 able-bodied reference subjects (gray). Data is presented for the gait cycle of 1.6 m/s walking, 2.6 and 4.0 m/s running. The take off is indicated by a vertical line. Positive values imply lengthening. Light gray color indicates the pattern for the theoretical model. As detected locomotion speed is different from the desired model and the treadmill speed real nut reference (black) curves differ from the model trajectory