A team of engineers designing robots to act as an intelligent swarm have managed to get them to use a type of pheromone-based communication normally used by groups of insects. The team from the University of Lincoln consider their breakthrough to be so significant that they are making it available to robotics and AI researchers across the country. Their initial findings were presented at the International Conference on Intelligent Robots and Systems (IROS) in Hamburg.
Pheromones are chemical agents produced by animals – particularly insects – and plants that induce a change in the behavior of another member of the same species. Secreted by a smorgasbord of fauna and flora, they come in a wide range of types that all have varying functions. Some mark habitation spaces (territorial pheromones), some are used to trigger aggression (alarm pheromones), and some are used to attract mates (sex pheromones).
Image credit: Follow the leader. Farshad Arvin/University of Lincoln
The mass use of pheromones by insects provides them with a rapid response communication system, and the research team wished to replicate it in robotics. Robots acting as swarms have a range of potential applications, ranging from using multiple, miniature micromachines to constructing larger, intricate objects, to sending a swarm to reach trapped humans in collapsed buildings after an earthquake.
Getting them to communicate almost instantaneously would greatly speed up their overall group behavior. At present, even the most rudimentary rule sets can lead to incredibly complex swarm behaviors; a constant feedback between each robot relaying, for example, where the outline of an object is will allow them to quickly migrate as a group around a physical space.
The information between each robot is normally transmitted via wireless systems using radio or infrared frequencies. This new method, using cheap “off-the-shelf” components to simulate pheromone releases, is reliable and precise.
Light sensors – analogous to the antenna of insects like ants – are fitted onto the small robots, which are designed to respond to visual stimulations on an LCD screen that they are placed on. Pheromones are simulated using these visual displays, which change in intensity at the command of the researcher. The wheeled robots are then allowed to move around freely, whereupon a “pheromone” is “released” – a visual pattern is emitted beneath one of the robots.
When the other robots come across this visual pattern trail, they quickly begin to follow it, and soon the robots are moving in tandem as a swarm. This artificial trail pheromone, if employed in the future to be released by the robots themselves, will allow for organizational, cooperative capabilities at unprecedented speeds. It is certainly far quicker than getting each of the robots to constantly transmit collision detection signals back and forth to each other, in order to build up a virtual image of where each of the members of the swarm are located.
This new system is called COS-phi (Communication System via Pheromone), and once again demonstrates that relatively simple rules can produce complex group behavior. Farshad Arvin, a Ph.D. researcher in the School of Computer Science at the University of Lincoln, and the lead researcher behind the system, said in a statement: “We can produce precise and high resolution trails, control the diffusion, evaporation and density of the pheromones, and encode individual pheromones using different colors. COS-phi also simulates the interaction of different pheromones that can amplify or suppress each other, resulting in complex swarm behaviors, just as they do in the natural world.”