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January 3 - Febuary 28, 2021

Meeting Abstract

73-2  Sat Jan 2  Simultaneous wing opening and leg flailing enables strenuous ground self-righting in cockroaches Othayoth, R; Li, C*; Johns Hopkins University

Self-righting when flipped over on the ground is strenuous for many terrestrial animals. During self-righting, the discoid cockroach often pushed its wings against the ground to begin a somersault by pitching up its body. However, despite repeated wing opening attempts, the animal rarely somersaulted successfully but instead often rolled to its side to self-right. Its legs flailed frequently and desperately in this process. Here, we studied whether simultaneous wing opening and leg flailing is beneficial. We tested a robot with two wings and a pendulum leg that swings laterally. We chose wing opening and leg oscillation amplitudes to generate similar strenuous self-righting behavior as the animal’s (no successful somersault, probabilistic self-righting via rolling). As wing opening and leg flailing amplitudes increased, self-righting probability increased. We used a potential energy landscape model to quantify the potential energy barriers to self-right. Without leg flailing, the pitching kinetic energy generated by wings pushing against the ground was insufficient to overcome the high barrier to self-right by pitching. Similarly, without wing opening, the rolling kinetic energy fluctuation generated by leg flailing was insufficient to overcome the small barrier to self-right by rolling. However, when used together, wing opening reduced the rolling barrier and enabled the kinetic energy fluctuation from leg flailing to probabilistically induce barrier-crossing, resulting in self-righting by rolling. Our study demonstrated that animals and robots can modify their potential energy landscapes to facilitate locomotor transitions using kinetic energy fluctuation. It also suggests that appendage coordination is important during strenuous self-righting (see Xuan and Li, 2020, Bioinsp. Biomim. and IEEE Rob. Auto. Lett.).