2007 Volume 127 Issue 6 Pages 643-650
In this paper, we propose a visual tracking method for a moving object without tracking delay. On visual servoing, image-based method with image Jacobian is often taken for target-centering camera motion control because it does not require target's 3D position estimation and is robust to modeling errors and noises. In an ordinary visual servoing approach, it is assumed that the target object would be fixed in the workspace. Therefore, for the purpose of tracking to a moving target, the image errors always exist between the target position and camera optical axis, that is, the visual tracking delay. In our proposed method, the target object's 3D position is estimated with the technique based on triangulation on stereo vision system. Then, the moving velocity is calculated in the camera coordinate frame. The image Jacobian concerns the camera velocity with the target velocity in the image plane. Additionally, the target velocity in 3D workspace is also converted into the velocity in the image plane. The converted velocity compensates the camera velocity to compensate the camera motion delay. This approach enables to achieve non-delayed tracking for moving target.