Feed-forward tracking servo system for high-data-rate optical recording

A high-speed and highly precise track-following control system for high-data-rate optical recording is proposed. We are developing an optical disk camera-recorder to record high-definition television signals for collecting broadcast program materials. This system must have both a high data transfer rate of more than 100 Mbps and a large recording capacity. That requires high-speed rotation of the optical disk and highly-precise optical head control for tracking on narrow-pitch disks. To meet these requirements, we propose a new tracking control method consisting of a feedback controller and a feed-forward controller that employs the zero phase error tracking method. Simulation results show that the feed-forward controller suppresses tracking error. Suppression of tracking error is also shown by experiments using an optical disk tester composed of a blue-violet laser and a high-density optical disk controlled by an experimental device that implements the optimized algorithm of this control method at high speed.