Disturbance Compensation Control in Media-Handling System
Ichiro Yamada, Kazumasa Kaneko and Makoto Takayanagi
NTT Interdisciplinary Research Laboratories, 3-9-11, Midori-cho, Musashino-shi, Tokyo 180, Japan
Mass storage systems (MSS) equipped with automatic media-handling mechanisms have become widely used in the field of information processing, and higher speed of media handling is desired. This paper investigates faster media handling achieved by using an observer to compensate for disturbances such as solid friction and inertia variations. First, two disturbance observers are introduced in the handling mechanisms. One is an adaptive observer of nonlinear characteristics of solid friction. The other is a constant disturbance observer. These observers can estimate solid friction as well as state variables such as velocity. In addition, by using these disturbance observers to estimate the state and to test the positioning control of a media-handling mechanism, the effectiveness of the observers is confirmed. It is also shown that a disturbance observer can be used to compensate for inertia variations.