Real-Time Visual Servoing Using Controlled Illumination

Abstract

A real-time visual servoing approach is applied to robotics tasks consisting of the positioning of the end effector with respect to a priori known polyhedral objects. The vision appa ratus is constituted by a compact CCD camera rigidly coupled with two laser stripes mounted on the wrist of a robot ma nipulator. The objective is to servo the robot end effector at a constant position and orientation with respect to a known object in three-dimensional space in the field of view of the sensory system. The approach is expressed in terms of sensor-based control (Samson et al. 1991) applied to visual servoing (Chaumette 1990; Urban 1990). In the case of camera—light stripe coupling, the elementary visual signals used for visual servoing are the points of discontinuity in the light stripes. The feasibility of the approach is demonstrated in a factory automa tion task consisting of the positioning of the end-effector tool over a vehicle battery. Both simulation and experimentation results are presented, proving the robustness and stability of the algorithm.