Omnidirectional vision system using two mirrors

Abstract

Obtaining omnidirectional visual information for a study of mobile robots is important for understanding robot positioning. Usually, such vision systems use a fish-eye lens or a reflecting mirror (conical, spherical or hyperboloidal). A conventional system has a problem in that an unnecessary visual field occupies most of the image. The conventional one also has a problem where the camera image is blurred due to the physical property of the mirror and a clear image cannot be obtained, especially in a dark environment. In order to overcome these difficulties, we propose an omnidirectional vision system using two mirrors with a contrived curvature for obtaining a panoramic image. The vision system consists of two axisymmetric mirrors (like a reflecting telescope) and a CCD camera. Incident rays from 360 degree surroundings are reflected twice by a primary mirror and a secondary mirror, then enter the CCD camera. A theoretical consideration is made to estimate the degree of aberration for the reflecting optical system and it uses two mirrors with arbitrary curvatures. The design method is developed to minimize the aberration of the image after the reflections of the two mirrors. The vision system can realize a clear omnidirectional panoramic image with minimum blur. The optical characteristics of the design are evaluated and the results show the effectiveness of the proposed vision system.