Disk drive control with the laser doppler vibrometer

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Magnetic hard disk drives are widespread and indispensable storage media nowadays. The storage media has been widely used in various applications ranging from lap-top computers, mobile audio players, car navigation, to security and communication systems. A current goal of the magnetic disk drive industry is to break the 1 tera-bit per square inch storage density barrier, which imposes a stringent performance specification for the conventional single-stage disk drive servo. To meet the challenge, several dual-stage actuation schemes have been proposed. All these proposals, however, lead to a multivariable servo system for which conventional scalar design techniques become inadequate to fully exploit the potential of that system. Thus, it is imperative to come up with appropriate design methodologies for the dual-stage multi-sensing system, in which optimal, robust performance is pursued in an explicit and systematic way. This proposal is a response to this need.   The proposed work aims to apply robust control theory to track-following control for dual-stage multi-sensing systems and to develop comprehensive user-friendly software package utilizing our controller design procedures. The ultimate goal is to invent a universal robust servo design technique applicable to control problems in various fields of engineering and science. All the obtained results will be tested by using a real hard disk drive experimental setup, in order to demonstrate the validity, the robustness, the efficiency, and the realizability of the designed controller. For disk drive control experiments in a laboratory, the Laser Doppler Vibrometer, that is an instrument specialized for accurate, non-contacting measurements of displacements and vibrations, is indispensable to determine the quality of the track-following control performance. In this project, this device will be utilized for various purposes, such as dynamics identification, detection of suspension vibration, and servo quality judgment. Other applications in areas such as aerospace engineering and biology will also benefit from the outcome of this research, as many problems in these areas are mathematically similar to that in the disk drive servo.