Pi Robot demonstrates an improved head tracking algorithm in this video while trying not to be distracted by the other actors in the room. Comparing this video to Pi's very first video (also head tracking), there are two differences: first, Pi's head movements now anticipate the moton of the ball by a few video frames (about 100 ms) by predicting its future position based on its current position and velocity. As a result, Pi's head no longer lags behind the moving ball as much as it did in the first video. Second, if the ball moves completely out of Pi's field a view, a new "visual search" thread kicks in that moves the head a large amount in the last known direction of the ball. In this way, Pi is able to re-acquire the ball even when it complete leaves his field of view.
