Real-time tracking of an unpredictable target amidst unknown obstacles

This paper describes a new approach to keep a moving target into the field of view of a robot, despite obstacles. Unlike previous work, this approach does not assume that a complete or partial model of the target´s behavior is available, nor that a map of the obstacles is given. At approximately 10 IIz, the robot constructs a local map of the environment from range data, localizes the target in this map, and computes its new velocity command. This command is selected to minimize a function that measures the risk that the target may escape the robot´s field of view by crossing an occlusion ray created by an obstacle. The risk function defined in this paper combines a reactive term, whose minimization handles immediate threats, and a look-ahead term, whose minimization improves the robot´s future ability to react to evading motions of the target. The experimental robotic system has been remarkably successful at tracking a target performing brisk maneuvers and swift turns behind obstacles.