Abstract :
Summary form only given, as follows. Anyone who has watched a fly make a flawless landing on the rim of a teacup, or marvelled at a honeybee speeding home after collecting nectar fiom a flower patch several kilometres away, would know that insects possess visual systems that are fast, reliable and accurate. Insects cope remarkably well with their world, despite possessing a brain that carries fewer than 0.01% as many neurons as ours does. Although most insects lack stereo vision, they use a number of ingenious strategies for perceiving their world in three dimensions and navigating successfully in it. For example, distances to objects are gauged in terms of the apparent speeds of motion of the objects\´ images, rather than by using complex stereo mechanisms. Grasshoppers estimate the distance to targets by moving their heads from side to side, and measuring range in terms of the speed of the target\´s image on the retina. Bees distinguish objects from backgrounds by sensing the apparent relative motion at the boundary between object and background. Narrow gaps are negotiated by balancing the apparent speeds of the images in the two eyes. Flight speed is regulated by holding constant the global image velocity as seen by the two eyes. Bees landing on a horizontal surface hold constant the image velocity of the surface as they approach it, thus automatically ensuring that flight speed is close to zero at touchdown. Foraging bees gauge distance flown by integrating optic flow: they possess a visually-driven "odometer" that is robust to variations in wind, body weight and energy expenditure. This presentation reviews some of this work, and outlines applications of some of these strategies to the design of autonomous, visually-guided robots.
