The data in Figure \ref{490314}A show a relationship between gait type and ya. For instance, trials at larger ya (13 to 15 cm) exhibited the “crawl” gait where both feet remain on the ground, and trials at smaller ya (9 to 12 cm) exhibited gaits where feet are lifted off the ground (e.g., run, walk) due to the higher magnetic field strength. Moreover, as the mass of MR-LF increased, a higher magnetic field strength (i.e., smaller ya) was required to produce the same gait type. For instance, at ya = 12 cm, the lightest MR-LF exhibited a “walk” gait, while the heaviest MR-LF exhibited a “crawl” gait. As noted in the previous section, the high magnetic field strength at ya = 9 cm caused all robots except the 4.43 g MR-LF to be lifted to the top of the channel and exhibit an “inhibited” gait. Similarly, the magnetic field strength at ya = 10 cm resulted in an “ inhibited” gait during some of the experiments (“IR*” classification applied when effective run gait began after the tenth step). Due to this transition between “run” and “inhibited” gait at high field strengths, the “run” gait may not be as desirable as the “walk” or “crawl” gaits if the goal is to maintain consistent robot locomotion. The gait characteristics and analysis presented here can inform future studies where a particular target gait can be achieved, refined, and tailored for a specific application.
Representative images, shown in Figure \ref{490314}B, demonstrate the “run,” “walk,” and “crawl” gait types of the MR-DF and the MR-LF of equal mass (2.55 g). A comparison between the images demonstrates that localizing flexibility enabled the creation of a centralized compartment without impeding the robot’s locomotion characteristics (Figure \ref{490314}B, Movie S1-S3, Supporting Information).