Maintaining the trend towards higher track densities and data rates in
rotating memory devices require track following servo systems of incr
easing bandwidth for reliable storage and retrieval (R/W) of data, The
bandwidth requirements are even more severe in the emerging portable
computing applications, Increase in bandwidth under strict constraints
on over-sampling is limited by the presence of mechanical resonance m
odes and other nonlinearities in the voice coil motor (VCM) actuators,
One approach to overcoming the problem is by using a dual or a compou
nd actuator, In such a mechanism, a VCM is used as a primary stage whi
le the recording head is mounted on the secondary stage which in turn
is mounted on the VCM. The secondary stage provides rapid small-motion
and position correction to the recording head, Several dual-stage con
figurations have been proposed using electrostatic, piezoelectric and
electromagnetic secondary actuators, The paper proposes a piezoelectri
c stack micro-actuator design for a disk drive. It preserves the prese
nt suspension and head assembly, A prototype of the actuator is design
ed, fabricated, and tested. The test results are presented, A dual act
uator tracking servo system is proposed, The scheme is a promising alt
ernative for providing high bandwidth actuation for future high perfor
mance drives.