Gliders in shape-changing active matter

TL;DR

This study demonstrates the spontaneous formation and dynamics of glider-like bound pairs in shape-changing active robots, revealing mechanisms of emergent attraction driven by local repulsive interactions.

Contribution

It introduces experimental and simulation evidence of shape-changing robots forming stable, traveling pairs called gliders, a novel collective behavior in active matter.

Findings

Gliders form robustly over various parameters.

Two distinct binding symmetries observed.

Effective attraction arises from repulsive interactions.

Abstract

We report in experiment and simulation the spontaneous formation of dynamically bound pairs of shape changing smarticle robots undergoing locally repulsive collisions. Borrowing terminology from Conway's simulated Game of Life, these physical `gliders' robustly emerge from an ensemble of individually undulating three-link two-motor smarticles and can remain bound for hundreds of undulations and travel for multiple robot dimensions. Gliders occur in two distinct binding symmetries and form over a wide range of angular flapping extent. This parameter sets the maximal concavity which influences formation probability and translation characteristics. Analysis of dynamics in simulation reveals the mechanism of effective dynamical attraction -- a result of the emergent interplay of appropriately oriented and timed repulsive interactions.