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. Author manuscript; available in PMC: 2014 Jun 1.
Published in final edited form as: Bioinspir Biomim. 2013 Mar 6;8(2):026002. doi: 10.1088/1748-3182/8/2/026002

Figure 4.

Figure 4

Representative data from the McKibben actuator array contracting against a 20 N load. For each trial, we analyzed measurements from when the load left the ground until one second afterwards (gray bar). (a) The relative shortening of the actuator (dashed) and array (solid) during the contraction. In all trials the amount of array excursion measured in the vertical direction exceeded the shortening of individual actuators. For this trial the initial length of the actuator is 30.2 cm. (b) Changes in pennation angle during the contractions. In all trials shortening of the actuator along its length was accompanied by changes in its orientation relative to the vertical (pennation angle). (c) Increase in array thickness during the contraction. (d) A plot of instantaneous gear ratio during the trial.