Disclosed is an apparatus and method for reducing vibration in dual stage
actuators of storage devices such as hard disk drives. The apparatus comprises
a compensating mass disposed on an outer arm of the storage device in order to
balance the mass and inertia of the outer arm. The compensating mass is provided
with an actuator that is driven in unison with a dual stage actuator also disposed
on the outer arm. The excitation caused by the dual stage actuator is balanced
by the excitation caused by the actuator of the compensating mass. The shape and
mass of the compensating mass are selected to simulate the mass and inertia of
the inner dual stage actuator. By driving the inner dual stage actuator in unison
with the actuator and compensating mass, the torsional input of the voice coil
motor is substantially reduced.
