AntBot: a six-legged walking robot able to home like desert ants in outdoor environments

International audienceAutonomous outdoor navigation requires reliable multi-sensory fusion strategies. Desert ants travel widely every day showing unrivalled navigation performances, using only a few thousand neurons. In the desert, pheromones are instantly destroyed by the extreme heat. To navigate safely in this hostile environment, desert ants assess their heading from the polarized pattern of the skylight and judge the distance travelled based on both a stride-counting method and the optic flow, i.e., the rate at which the ground move across the eye. This process is called the path integration (PI). Although many methods of endowing mobile robots with means of outdoor localization have been developed recently, most of them are still prone to considerable drift and uncertainty. Here it was proposed to test several ant-inspired solutions to outdoor homing navigation problems on a legged robot using two optical sensors equipped with just 14 pixels, two of which were dedicated to an insect-inspired compass sensitive to ultraviolet light. When combining with two rotating polarized filters, this compass was equivalent to two costly arrays composed of 374 photosensors, each of which tuned to a specific polarization angle. The other 12 pixels were dedicated to optic flow measurements. Results show that our ant-inspired methods of navigation give precise performances: the mean homing error recorded during the overall trajectory was as small as 0.67% under similar lighting conditions to those encountered by ants. These findings show that ant-inspired PI strategies can be used to complement classical techniques with a high level of robustness and efficiency