Is 3D useful in stereo visual control?

The main goal of this paper, is the study of image-based stereo visual servoing. A pair of cameras is mounted on the end-effector of the manipulator arm. The visual features are the pair of images of an unknown object. The developed control laws use either the raw image points, or the estimated 3D coordinates. The experimental setup is challenging: large rotations are involved, images are noisy, and cameras are coarsely calibrated. In this setup, the trajectory of the end-effector differs notably, sometimes leading the arm near its joint range limits. Experimental results demonstrate that using pixel coordinates is disadvantageous, compared with 3D coordinates estimated from the same pixel data.