03-11-2012, 05:10 PM
Design and Implementation of a Hard Disk Drive Read/Write Head Controller Using FPGA for Optimal Performance
Design and Implementation.pdf (Size: 226.93 KB / Downloads: 73)
ABSTRACT
Many automatic control systems utilize digital control algorithms for the
control of desired plant. Fast processing in recent microelectronics
components and flexibility inherent for all these programmable solutions
gave favor to digital control applications from software-hardware
solutions using FPGA. This paper investigates an FPGA-based PID
control system for Hard Disk Drive read/write system. An attempt has
been made to design and implement a feedback control system using
FPGA for optimal performance. Ultimately, the optimally controlled
movements of Hard Disk Drive read / write head has been achieved.
Introduction
In today’s engineering environment, a rapid move from design concept through
solution requires suitably defined formal methods, along with effective software support
tools. To address this, a reconfigurable technique based on Field-Programmable Gate
Arrays (FPGAs) may be applied, which has the potential for greater functionality and
higher performance with smaller volume and low power dissipation. The reconfigurable
computing has grown to become an important and wide field of research. The operation
of each primitive can be programmed, and also the interconnection pattern, computation
tasks can be implemented spatially on the device directly from the producing function to
the receiving function. Since we can put thousands of reconfigurable units on a single die
Disk Drive Read/Write System
Hard disk drive provides important data-storage medium for computers and other
data-processing systems. The two main functions of the R/W head positioning servo
mechanism in disk drives are Track Seeking and Track Following.
Track seeking moves the R/W head from the present track to a specified destination track
in minimum time using a bounded control effort. Track following maintains the head as
close as possible to the destination track center while information is being read from or
written to the disk.
Formulation of the Problem
The problem of Disk Drive Read/Write System[1] is formulated in step by step
procedure as:- Step 1: The control goals are established (a) to position the reader head
accurately at the desired track and (b) to move from one track to another within 50
milliseconds if possible. Step 2: Setting the variable to accurately control the position of
the reader head (mounted on a slider device). Step 3: The disk rotates at a speed between
1800 and 7200 rpm, and the head “flies” above the disk at a distance less than 100 nm.
The initial specification for the position accuracy is 1 micro-meter. Thus, we establish an
initial system configuration as shown in Fig. 1. This system uses a motor to actuate the
arm to the desired location on the disk.
Conclusions
Tremendous improvements are obtained in implementing the system design onto
the FPGA device. The overshoot in the FPGA design has zero percent. A very fast
response to a step input giving the rise time of 0.763μs. The settling-time has been
reduced to 1.367μs. The results, in case of hard disk drive system are very encouraging to
design, simulate and implement the higher order complex control systems onto the
FPGA, so that the System-On-Chip (SOC) can be developed.