In order to fly a number of single rotor units join up with one another to form a viable aircraft. Individually the units are unable to fly but this changes when they join up and co-operate in order to fulfill their mission.
More details - and videos - can be found here.
Glasgow trial explores AR cues for autonomous road safety
They've ploughed into a few vulnerable road users in the past. Making that less likely will make it spectacularly easy to stop the traffic for...