2012 METU Lecture 5 Control of Smart Systems - Department of ...

Design Challenges
• To design each of the four main components of the disk drive
servo system – plant dynamics, sensors, actuators, and control
algorithms – and to reduce the effect of mechanical disturbances
to the drive.
• Disturbances arise from many sources: external shocks and
vibrations, mechanical imperfections in the bearings of the disk
spindle, disk vibrations, turbulent flow over the actuator due to
air currents generated by the rapidly spinning disks, and the
occasional contact between the slider and the disk.
• Plant dynamics which affect servo performance are mechanical
resonances in the suspension (the leaf spring that holds the head
against the disk), the actuator arm, the pivot bearing, and the
voice coil.
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