Fig. 4

Stance traces and inter-leg coordination parameters. a Stance traces. Representative plot of an animal walking at 34.8 cm/s. Traces are generated by the position of the stance phase footprints relative to the body center (set at 0.0, 0.0). For each leg, stance onset corresponds to the anterior extreme position (AEP, marked by a dashed line) while stance offset is termed the posterior extreme position (PEP). b Stance linearity index decreases as a function of speed. Each data point measures the average jitter of the stance traces for all the legs. x-axis error bars represent standard deviations of the average speed. c Footprint clustering values are on average higher for PEP compared to AEP and increase with speed. d Gait patterns and step combinations. From top to bottom: Gait patterns (white areas represent swing phases and gray areas represent stance phases), instantaneous speed, color-coded leg conformation, and leg combination traces. e–g Leg combination indexes. y-axis upper limits are set to 0.9 to facilitate comparison. Graphical fits are also represented. e Diagonal swing index as a function of speed. Diagonal swing is the most representative leg combination, which increases with speed. f Single swing index decreases significantly with increased speed. g The all-legs swing index is observed primarily at higher speeds. The inset is the adjusted y-axis. The vertical dashed line is the transition from a walk to run-like behavior