A planar omnidirectional treadmill to study insect locomotion

Hendrik Beck
PhD student
Imperial College London, UK
Lab webpage: https://evo-biomech.ic.ac.uk/

Abstract
Insects seem to move effortlessly in a variety of habitats. They can walk upright, climb up vertical walls, stick to inverted surfaces, and are robust to the loss of one or even multiple limbs. Studying these fascinating locomotive skills has been a long-standing source of inspiration for six-legged walking robots. However, obtaining high-quality biological 3D kinematics data remains difficult and at best tedious – insects generally do not cooperate. Previous work utilized spherical treadmills that were either passively or actively actuated to tackle these issues. However, passive actuation requires tethered insects, and active actuation still requires either large spheres or involves a restricted recording area, requiring rapid feedback loops that may perturb natural locomotion.

To circumvent these limitations, we developed a planar omnidirectional treadmill, which perpetually keeps walking insects in a central region of interest. In brief, a set of small treadmills is mounted on a large treadmill; the small treadmills and the large treadmill move in perpendicular directions, and are actuated by independent motors; the insect’s position on the treadmill is tracked in real-time, and serves as the control input.
The treadmill design allows observation of natural locomotion on a flat surface; insects can freely select speed and walking direction over long periods of continuous gait cycles. By deploying our treadmill to study the 3D kinematics of insect locomotion, we hope to provide a better understanding of how six-legged walking systems, insect and hexapod robots, adapt to different mechanical scenarios.