Each robot is following the robot with an ID one less than their own. The robot in the front is being controlled remotely. Communicating through the state of the environment Information does not always need to be explicitly transmitted from robot to robot. The shape formation demo is one example of the robots using themselves as markers in the environment for other robots to use as references. Leaving and sensing trails is another example of this communication technique.
Robots can leave water trails in their environment.
These trails can be then be followed by other robots. In essence, this allows an individual robot to communicate to other robots indirectly. This ability can be used to allow the group as a whole to make decisions on where to forage, or which direction to move in. Infrastructure Building the resources required to allow swarm research to happen in an efficient fashion is almost a project onto itself. The All Terrain Swarm Transport.