Control strategies for visual tracking from a moving platform

This paper outlines the control algorithms used in a pan/tilt/zoom (PTZ) tracking system for an Unmanned Ground Vehicle (UGV), implemented as part of a computer-vision based autonomous convoying system. The system relies upon a Linear Quadratic Gaussian controller to keep the target centered in the camera´s field of view using the pan and tilt degrees of freedom. A novel zoom controller, based upon the current target size and various measures of system noise, controls the camera focal length to maintain an appropriate image size for visual tracking, despite changing distances between the leader and follower vehicles.