Why do periodic gaits exist?

(This is a recording of a seminar given 2024-06-24 at the Mechanical Engineering Department, Technion, ISRAEL)
This talk will show that the appearance of periodic gaits in multi-legged animals should be surprising from the mechanical perspective, and propose a novel hypothesis for why they exist.
Most terrestrial animals move using legs that push against a substrate. Viewed from the animal's body frame, the legs undergo rhythmic oscillations which are often modeled as a periodic solution to some mechanical equation of motion - a "periodic gait". First, we will review some of the vast biomechanical literature that attempts to explain why periodic gaits exist and why animals select different gaits under different conditions. This will demonstrate that these explanations do not apply to small animals with many legs, leaving a puzzle, which will lead to a new hypothesis for why periodic gaits are biologically prevalent, and potentially, why they are a good idea for multi-legged robot designs.
The talk will be suitable for an audience with an interest in mechanics, biomechanics, robotics, or control, and an undergraduate level background in dynamics or dynamical systems, and can serve in part as an introduction to the biomechanical literature on animal gaits. This work was funded in part by ARO MURI W911NF-17-1-0306, NSF CMMI 1825918, NSF CPS 2038432, and D. Dan and Betty Kahn Michigan-Israel Partnership for Research and Education Autonomous Systems Mega-Project.