Emergence, dynamics and control of topological defects in odd robotic matter

Active systems are not constrained by the principle of energy conservation, allowing for a wide variety of wave phenomena not accessible to ordinary passive matter. By implementing local energy non-conserving interactions between particles within a network, complex collective behaviour can result, providing new avenues in material design.

In particular, odd elastic materials — materials in which both energy conservation and chiral symmetry are broken — can be constructed by considering Hookean springs with restoring forces which depend on the actuation direction. Starting from simple building blocks made from robotic units equipped with sensors and actuators, I show that odd robotic metamaterials feature self sustained work cycles that give rise to unidirectional waves and topological defect dynamics. Through smart choices of geometry and topology, these systems of distributed engines can be leveraged to power impact control and locomotion. More generally, they represent an ideal platform to study, engineer and control the emergent properties of active systems, facilitating the development of autonomous smart materials, topological sensors and noise suppression schemes.