Smarticle glider: Locomoting, spontaneous excitations in a shape changing active matter system

Smarticles or smart active particles are 3 link robots which change their shape periodically through the actuation of the arms. Limited individually in their ability to translate or rotate in the current experimental setting, they exhibit interesting collective behavior (directed locomotion) as a result of stochastic mechanical interactions (W, Savoie et al., Science Robotics 2019). The glider, which is a two smarticle bound excitation, is the fundamental building block for these phenomena. It has a lifetime of about 90 periods and moves about 4 body lengths before dissociating. We seek to understand the mechanistic principle behind the creation of these states and their ensuing dynamics with an iterative map. Simulations reveal that for these excitations to locomote, there must be fluctuations in the coefficient of friction. Since the smarticles only interact with each other via collisions, gliders are essential to keep a cloud of smarticles connected and hence harness their collective behavior.
Reference:
A robot made of robots: Emergent transport and control of a smarticle ensemble, W. Savoie et al., Science Robotics 2019.