Techniques for disk servo track following

Abstract

Abstract Described is a novel technique and associated arrangement for determining the noise-free value of a system parameter (e.g., head position in a disk drive) which is time variable and (usually) has a noise component as detected. The technique involves processing the (as detected) noise-including value and passing it through "Second Order/Summing" filter means. For instance, the technique is described as particularly useful with the "track-following servo" (part of the transducer positioning means) in a high density disk file (where track density is higher than usual) to secure superior head-displacement error values which are more noise-free. Thus, (see FIG. 4), a pair of first values V a , V b are secured by detecting motor current sense voltage V i , integrating it with respect to time and passing the result through a pair of novel "second order filter" means--one hand-pass (F 1 ) the other low-pass (F 2 ); while also securing a third value V c by detecting position error (signal voltage, including noise components) in the usual manner and passing it through a "secod order low-pass" filter F 3 ; then algebraically summing these to secure a relatively noise-free position error signal V xo [V.sub.xo =V.sub.a +V.sub.b +V.sub.c ] Thus, the summing filter array gates the position-error voltage but attenuates the (mechanical) noise component (cf. filters F 2 , F 1 centerd at w o --e.g., 600 Hz is satisfactory here). Such "second order" filters are novel in themselves, and particularly as so applied (most especially as so-used in such a servo system).

Inventors

• 👤 Ashraf I. El-Sadi

Bibliographic Details