Fig. 2
From: Predicting reactive stepping in response to perturbations by using a classification approach
Top: Vertical ground reaction forces acting on the right foot of subject S9. The ground reaction forces were used to detect step leg unloading (circles) and toe-off (crosses) for a selection of stepping (red) and non-stepping (blue) responses. For one of the stepping responses all prediction time steps are shown (dots). The grey area represents the duration of the perturbation. Bottom: Timing of prediction time steps (in seconds) with respect to toe-off of subject S9. SLU indicates step leg unloading, TO indicates toe-off, tSLU−n and tTO−n indicate the nth time step before step leg unloading and toe-off respectively. Note that the times are rounded to the nearest hundredth, since motion data were collected at a 100 Hz