Depth from Vergence and Active Calibration for Humanoid Robots

In human eyes, many clues are used to perceive depth. For nearby tasks involving eye-hand coordination, depth from vergence is a strong cue. In our research on humanoid robots we study binocular robotic eyes that can pan and tilt and perceive depth from stereo, as well as depth from vergence by fixing both eyes on a nearby object. In this paper, we report on a convergent robot vision set-up: Firstly, we describe the mathematical model for convergent vision system. Secondly, we introduce an algorithm to estimate the depth of an object under focus. Thirdly, as the centers of rotation of the eye motors do not align with the center of image planes, we develop an active calibration algorithm to overcome this problem. Finally, we examine the factors that have impact on the depth error. The results of experiments and tests show the good performance of our system and provide insight into depth from vergence.