85-8 Saturday, Jan. 6 11:45 - 12:00 Body vibrations induced by legged locomotion help traverse complex 3-D obstacles THOMS, G; LI, C*; Johns Hopkins University firstname.lastname@example.org https://li.me.jhu.edu
Legged locomotion offers natural advantages in complex terrains. When insects and legged robots encounter complex 3-D terrains such as grass-like beams, a rounded body shape helps them roll to traverse narrow slits between beams. In this process, intermittent leg-ground contact induces the animal/robot body to vibrate. Here, we tested the hypothesis that body vibrations induced by legged locomotion facilitate obstacle traversal using an automated robophysical system. To mimic a cockroach/robot body pushing against two adjacent grass blades, we used a linear actuator to move an ellipsoidal body into two adjacent beams with variable spacing. To mimic body vibrations induced by legged locomotion and systematically control and modify the direction and magnitude, we used actuators to generate translational and rotational oscillations on the body. A gyroscope mechanism allowed the body to freely rotate in response to interaction with the beams, and an IMU and cameras recorded the motion of the body and beams. We discovered that both translational and rotational body vibrations facilitated body rolling, increasing traversal probability and reducing traversal time (by 50-80%) as compared to the body without vibration (P < 0.0001, ANOVA). Traversal probability increased with and traversal time decreased with beam spacing, suggesting that a more cluttered grassy terrain is more difficult to traverse for a legged animal or robot. Finally, we developed a locomotion energy landscape model to reveal that the kinetic energy from body vibrations better allows the interaction system to explore its state space and find the pathway of rolling traversal, which overcomes the lowest potential energy barrier. Our study supports the plausibility of locomotion energy landscapes for understanding how locomotor transitions emerge in complex 3-D terrains.