Active Vision for Low Cost SCARA Robots Using RGB-D Camera

In this paper, an active vision approach for low cost robots without absolute encoders, relying on visual feedback only is proposed. Lacking absolute encoders, positioning of a robot arm is performed by visual servoing based on detection of a marker mounted close to the end effector. In order to achieve a wide field of view, an RGB-D camera is set on a pan-tilt head. Since each change in pan and tilt angles of the camera results in a change in relative positions between the robot reference frame and the camera reference frame, constant hand-eye recalibration is required. Both hand-eye calibration and visual servoing require visibility of the marker in the camera field of view, which is ensured by an active vision strategy. Active vision also includes search for object of interest on the scene. The proposed method is evaluated using a real robot arm in SCARA configuration.