Abstract:

When service robots provide daily services,different tools may be held by the gripper on the robot arm from a right angle,but it is hard to measure directly and exactly the pose relationship between hand-eye systems and endmost tools.In this paper,we calibrate this relationship by only utilizing a bifocal monocular camera focusing on the eye-in-hand system by three steps.Firstly,we propose a method to calculate the focal length after camera focusing.Secondly,taking camera focusing as the camera translation along the optical axis, we present a method to detect the position and the pose of the endmost tools in the camera and in the manipulator coordinate systems respectively according to the two images captured before and after camera focusing. Meanwhile, a method is given to calculate the direction vector from endmost tools to the expected position.

Key words: hand-eye system;bifocal camera;pose calibration of endmost tools;direction vector