<title>Calibration of the active stereo vision system KASTOR with standardized perspective matrices</title>

Abstract

In this paper the new active stereo vision head of the IPR is presented. It is designed to serve as a flexible sensing device mounted on a mobile robot platform. KASTOR has eight motorized optical and mechanical degrees of freedom. The article describes the design of KASTOR as well as the real-time vision system it is connected to. Then a new head calibration technique is presented. The perspective matrices are computed directly without the need to determine internal or external camera parameters. This is achieved by the observation of a reference object in a scene. As soon as the robot moves any of its degrees of freedom, the calibration has to be updated. However it is difficult and time expensive to define a reference object when the head is mounted on a mobile robot. A solution is to compute all possible perspective matrices in advance and to store them in the memory. During autonomous operation the correct matrices are selected according to the head-configuration. A standardizing technique is presented, which reduces the amount of matrices to be stored significantly. Finally the article discusses the quality of calibration when in use as active sensing device on a mobile robot.