A 3D Redundant Tracking Utility

 

Madden, Brian C., and Cahn von Seelen, Ulf M.

ECVNet Workshop on Active Vision Hardware, Grenoble, France, Feb. 1-3, 1995

Abstract: We present an active vision system that tracks an object in three dimensions. The system provides a pair of redundant but dynamically different degrees of freedom for each spatial dimension. The faster DOF tracks rapid movement of the target while the slower DOF brings the faster DOF back into the center of its range where it can respond best. In the horizontal direction, target movements are tracked with the camera pan, which servos on horizontal displacement in the image. The slower head pan (implemented as a rotation of the robot arm about its waist joint) makes the vergence symmetric. To track vertical target motions, the head tilt (implemented as a rotation of the robot arm about its wrist joint) servos on the vertical displacement in the image and is complemented by a slower raising or lowering of the head with the robot arm, which brings the head tilt back into the horizontal. Motions in depth are primarily tracked by the camera zoom which servos on the extent of the target in the image. As the slower degree of freedom, the robot arm moves the head closer to or away from the target.