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Fig. 11 | Journal of NeuroEngineering and Rehabilitation

Fig. 11

From: Reducing the metabolic cost of walking with an ankle exoskeleton: interaction between actuation timing and power

Fig. 11

Center-of-mass power calculations. Time series show population averages for center-of-mass power plotted from heel contact to heel contact (a). The grey vertical line represents opposite heel contact. All powered conditions are shown in grey, with selected conditions in color. Subplots at top show which conditions are shown in color. Blue rectangles show the periods where the rebound phase was present and where the average center-of-mass power was calculated for the positive burst. Repeated measures ANOVA indicated significant differences between conditions for the average center-of-mass power during this rebound phase (P < 0.001). This was calculated as the numerical integration of rebound power, divided by stride time. The effect of actuation timing and exoskeleton power on average center-of-mass power is indicated by a regression analysis (b). The surface gradient is the result of a two-dimensional regression for which R2 is provided (P < 0.001). The black dotted line shows the NormalWalking condition and the black dashed line shows the ZeroWork value. * indicates a statistically significant reduction versus ZeroWork and ** indicates a statistically significant reduction versus NormalWalking based on post-hoc t-tests with Šídák-Holm correction (P ≤ 0.05)

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