Kinetic Theory of Rectified Motion in a Smarticle Gas

Smarticles are battery powered, self-deforming, three link robots that undergo a repeated prescribed gait. When a small number are confined inside an untethered ring the system undergoes undirected (isotropic) diffusion. Upon deactivation of one of the smarticles, the system displays directed diffusion, with speed and direction which depend on the mass of the confining ring. We present a collisional model that accurately predicts the directed motion.