Excitations in an active smarticle gas

<p style="margin: 0px 0px 10.66px;"><font color="#000000"><font face="Calibri"><font size="3">Spontaneous stable excitations can arise unexpectedly from homogenous many body systems, e.g. oscillons observed in vibrating granular media, and rotons in superfluid helium. We have observed several such long lived excitations in a gas of active matter particles called “smarticles”. Smarticles are small 3 link planar robots. Each smarticle measures 14X2.5X3 cm</font>³</font><font face="Calibri" size="3">, where only the center link is on the ground. In the experiments they are placed on a frictional surface, and change their shape periodically, while interacting with each other via collisions. Although fairly limited in their locomotive capabilities on their own in the considered experimental configuration, interesting behavior is revealed when we allow these smart, active granular materials to mingle. We study the simplest case where two smarticles interact with each other. These two particle excitons demonstrate bouts of coordinated motion synchronized both in their gaits, and spatial orientations. We also witness a unique case of locomotion emerging from their mechanics, wherein the collective executes general planar motion.</font></font></p>