Loopy Movements: Emergence of Rotation in a Multicellular Robot

TL;DR

This paper demonstrates how a multicellular robot can achieve emergent, decentralized rotation through simple local interactions inspired by biological systems, maintaining functionality despite failures and morphological changes.

Contribution

It introduces a novel multicellular robot that self-organizes to rotate via local chemical interactions without centralized control, inspired by biological behaviors.

Findings

Inner valleys rotate faster than outer peaks, unlike rigid bodies.

Cells rotate opposite to the overall morphology.

Loopy maintains rotation despite actuator failures and morphological changes.

Abstract

Unlike most human-engineered systems, many biological systems rely on emergent behaviors from low-level interactions, enabling greater diversity and superior adaptation to complex, dynamic environments. This study explores emergent decentralized rotation in the Loopy multicellular robot, composed of homogeneous, physically linked, 1-degree-of-freedom cells. Inspired by biological systems like sunflowers, Loopy uses simple local interactions-diffusion, reaction, and active transport of simulated chemicals, called morphogens-without centralized control or knowledge of its global morphology. Through these interactions, the robot self-organizes to achieve coordinated rotational motion and forms lobes-local protrusions created by clusters of motor cells. This study investigates how these interactions drive Loopy's rotation, the impact of its morphology, and its resilience to actuator failures. Our findings reveal two distinct behaviors: 1) inner valleys between lobes rotate faster than the outer peaks, contrasting with rigid body dynamics, and 2) cells rotate in the opposite direction of the overall morphology. The experiments show that while Loopy's morphology does not affect its angular velocity relative to its cells, larger lobes increase cellular rotation and decrease morphology rotation relative to the environment. Even with up to one-third of its actuators disabled and significant morphological changes, Loopy maintains its rotational abilities, highlighting the potential of decentralized, bio-inspired strategies for resilient and adaptable robotic systems.