Swarm robotics is a new approach to the coordination of multirobot systems which consist of large numbers of mostly simple physical robots. It is supposed that a desired collective behaviour emerges from the interactions between the robots and interactions of robots with the environment. This approach emerged on the field of artificial swarm intelligence, as well as the biological studies of insects, ants and other fields in nature, where swarm behaviour occur.
In this example we will going to demonstrate the basic level of swarm robotics where two robots will talk to each other and would tell the other robot about the obstacle's.
Suppose the first robot find the obstacle's on his way it will tell another robot that there is obstacle ahead please take a turn .This is just like self driving car where two cars are communicating with other to avoid any accidents and smart enough to alert the other cars that there is some problem on the road ahead .This will prevent unnecessary time of other vehicles thus making the transportation smart.
You can also use this robot to make a 3D map of the place or use it as a radar to capture real time objects around the robot.
Check out this link if you are interested to make your robots plot the radar http://howtomechatronics.com/projects/arduino-radar-project/
Once you upload the code in both the robots and power up the Arduino using lipo battery you will see your two robots in an action. Make a nice obstacle path and test your robots ,modify the code if necessary.