An Autonomous Agent Navigating with a Polarized Light Compass

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Abstract
One of the fundamental abilities required in autonomous agents is homing. Natural agents—for instance, desert ants—solve the homing problem mainly by using path integration within an egocentric frame of reference. When employing such a mechanism, compass information for determining direction is necessary, and the precision of the compass will have a crucial effect on the precision of homing. For deriving compass information, certain insects use the pattern of polarized light in the sky that arises due to scattering of sunlight in the atmosphere (polarized light compass). The analysis of skylight polarization is mediated by specialized photoreceptors and neurons in the visual system. Inspired by the insect's polarized light compass, we have constructed a polarization compass that was employed successfully on the mobile robot Sahabot. Three models for extracting compass information from the polarization pattern of the sky were tested. In this article, we describe the navigation system and report results of experiments performed with the Sahabot in one of the natural habitats of the desert ant Cataglyphis in North Africa.