Meeting Abstract
Righting oneself from an upside-down orientation is one of the most prevalent locomotor transitions terrestrial animals perform to survive. Previous studies in crustaceans and insects described a diversity of self-righting strategies. Recent studies in turtles and robots begin to hypothesize self-righting mechanisms in the transverse or sagittal plane. However, few quantitative measurements exist on animals’ self-righting performance to test these hypotheses, particularly in three dimensions. Here, we study self-righting on a flat, rigid ground in three species of cockroaches differing in body size, shape, and availability of wings. We found that animal righting is a complex, dynamic, three-dimensional maneuver using multi-degree-of-freedom bodies and appendages. All three species self-righted successfully (75 ± 20 % righting probability) and quickly (as low as 140 milliseconds and typically within 2 seconds). However, their morphological differences result in distinct dominant behavioral strategies. The smallest, most agile, and winged American cockroach primarily kicked its legs against the ground (95% relative frequency) to self-right (0.7 ± 0.2 s). By contrast, the mid-sized, relatively agile, winged discoid cockroach most often used wings coupled with body flexion (62% relative frequency) to self-right (1.6 ± 1.0 s). The largest, least agile, and wingless Madagascar hissing cockroach hyperextended its body (90% relative frequency) and then rubbed its legs on the ground to self-right (1.2 ± 0.4 s). Results suggest that when appendages alone cannot generate a sufficient impulse, the ability to transform into an unstable body shape when upside down is critical to self-righting capability. Our study provides inspiration for robotics as many current terrestrial robots have rigid, cuboidal bodies which hinder self-righting.
