Screen capture, Alice (antbots) travelling the maze. (via BBC)
The highway traffic system can be a bit of a pain at times - rush hours leaving many heading home from work in a seemingly endless line of vehicles tiptoeing their way forward. There must be a way of achieving optimal travel, ants, for instance, seem to have it down pat. On their daily foraging missions, ant colonies efficiently travel great distances with the minimal aid of visual cues, pheromone based route tracking, sun positioning navigation, and can even count their number of steps and body rotations - not unlike many workout enthusiasts of today. But when faced with a fork in the road, it is possible that these ants use the geometric configuration of their environment to find the shortest route to the food source. This is the basis of the latest study at the New Jersey Institute of Technology’s Swarm Lab that employed an army of 10 ant-sized robots, named Alices, to do a bit of behavioral study on the matter.
The sugar-cube sized ant robots were equipped with two light sensing antennae for the study. In addition to testing the geometric variable in their route navigation system, ants’ method of using pheromones to navigate was simulated by light-trail that was left behind by each individual robot’s path down a maze. A previous study explained that the angle created by a fork in the road determined which path the ant would take: a small incident angle led to the food source, while a larger incident angle generally led back to the nest. Thus, the study was performed on two types of mazes: one with symmetrical bifurcations (forks in the road), and one with asymmetric bifurcations (more closely resembling and networks).
Alice bot (via BBC video)
Programmed to move much like ants whom follow a relatively straight path with little desire for exploration, the 10 robots were let loose in the maze galleries as the researchers paid close attention to the relationship between their interactive movements, light-trail navigation, and the bifurcation geometries. The results of the experiment demonstrated remarkably similar patterns of movement between the ants and the Alices. It turns out that the physical angle of the forks in the road were not as important in this case; By paying attention to light-trails left by other ant-bots, each subsequent robot would prefer to take the path that had been previously travelled by another bot. In this method, once the shortest route was found, more and more ant-bots would take that same route due to its increase light “pheromone” presence.
Simon Garnier, the research team leader, wasn’t too surprised that the experimented explained ant navigation behavior as dependent on both physical layout and the presence of pheromones. Ants still prefer to move through bifurcations with angle that require the least effort to maneuver through, hence the small incident angle, but also contain a stronger pheromone scent. The result is a positive feedback loop traffic system. The research will further help scientists study how physical layouts and pheromone trails in the environment can affect the travel of other insects. Hopefully, subsequent work will be done to study how similar methods can be used to alter human-made environments for optimal travel and trade that effectively eliminates traffic clogs.
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