Very interesting topic and briefing, I wonder if there is any form of redundancy, in case there are single or multiple vehicle failures ( due to obstacles, wind sheer or other forces that could knock off the comm, or the complete functionality ). I see a very challenging effort to keep it robust!
In-air collision avoidance was one of the criteria used by the Swiss Federal Office for Civil Aviation when issuing its license to operate beyond line-of-sight. Different algorithms are used, but one aspect is to make sure that UAVs in adjacent sectors are flying at different heights--similar to airliner requirements.
The missing element in the description seems to be how obstacles are avoided. If ants bump into an unexpected obstacle (slowly enough that no damage is done), their sense of touch enables them to detect the impact, reroute slightly, and continue in the intended direction. They remain firmly grounded throughout the process. Aircraft are much less forgiving about bumping into obstacles and then continuing on a slightly modified routing.
What an interesting idea! I am very curious to learn what form the airborne pheromones take. I could imagine a number of possible solutions but would like to know more from the designers. There is a lot of detail in the article and pictures but no sensors for use by the swarm? I was expecting video camera or airborne gas type sensors but could not discern any type of sensors in the diagrams. The pressure sensors would be used (I imagine) for flight / altitude control while the GPS for navigation. Still, a very neat idea to mimic ants, perhaps bee behavior would be a better model (given flight).