Emerging spatiotemporal patterns and collective swimming of magnetically actuated soft robots

Abstract The collective swimming of soft robots in an infinite viscous fluid is an emergent phenomenon due to the nonreciprocal hydrodynamic interactions between individual swimmers. These physical interactions give rise to unique spatiotemporal patterns and unusual swimming trajectories that are often difficult to predict because of the two-way fully coupled nature of the strong fluid–structure interaction at a far-from-equilibrium state. Until now, robotic collectives have mostly been studied for rigid swimmers in two-dimensional settings. Here we examine the emergence of three-dimensional spatiotemporal patterns and collective motion of magnetically actuated soft robotic swimmers by systematically studying the effect of different initial configurations. Our results show that swimmers with variations in initial positions in the swimming direction are attracted to each other. In contrast, swimmers with variations in lateral positions repel each other, eventually converging to a state in which all swimmers concentrate in one lateral plane drifting radially outward.