Method and apparatus for optimization of servo parameter values in a data storage device

• US 6,499,022 B1
• Filed: 10/06/1999
• Issued: 12/24/2002
• Est. Priority Date: 10/21/1996
• Status: Expired due to Fees

• Current Assignee: Maxtor Corporation (Seagate Technology Holdings Plc)
• Original Assignee: Maxtor Corporation (Seagate Technology Holdings Plc)
• Inventors: Alexander, James, Dittmar, Mark
• Primary Examiner(s): STARKS, WILBERT L
• Application Number:
  US09/413,299
• Time in Patent Office: 1,175 Days
• Field of Search: 706/13, 364/162, 364/161, 364/157, 364/165
• US Class Current: 706/13
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0634 by changing the state or mode of one or more devices
• CPC Class Codes: G06F 3/0674 Disk device
• CPC Class Codes: G06N 3/126 Evolutionary algorithms, e.g. genetic algorithms or genetic programming
• CPC Class Codes: G11B 20/10009 Improvement or modification of read or write signals
• CPC Class Codes: G11B 20/10055 using partial response filtering when writing the signal to the medium or reading it therefrom
• CPC Class Codes: G11B 20/10481 optimisation methods
• CPC Class Codes: G11B 2005/001 Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 27/36 Monitoring, i.e. supervising the progress of recording or reproducing for digital recording G11B20/00 and s.gr.; for monitoring, testing or measuring of TV recorders of the type covered by H04N5/76 and subgroups, see H04N17/06
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence

Abstract

A genetic process is used to tune servo parameter values in a disk drive. An initial population of individuals is generated each including a value for each of a plurality of servo parameters. Fitness values are then calculated for each of the individuals in the initial population. Individuals from the initial population are then chosen for mating based on the calculated fitness values. The chosen individuals are manipulated using genetic operators to produce a new population of individuals. Fitness values are then calculated for the new population and the cycle is repeated. The process is continued until a predetermined criterion has been met. After the process has ended, an individual is chosen based on fitness values and the servo parameters of the disk drive are set accordingly.

Claims

1. A method for tuning servo parameter values in a disk drive using a genetic process, said method comprising the steps of:

generating an initial set of parameter value groups, each of said parameter value groups in said initial set of parameter value groups including a value for each of a plurality of servo parameters;

first determining a servo performance quantity for each of said initial set of parameter value groups by performing a servo operation using servo parameter values associated with each group, wherein said step of first determining includes combining two measured servo performance values in a weighted combination;

generating a second set of parameter value groups using said initial set of parameter value groups and servo performance quantities corresponding to said initial set of parameter value groups, each of said parameter value groups in said second set of parameter value groups including a value for each of said plurality of servo parameters;

second determining a servo performance quantity for each of said second set of parameter value groups by performing a servo operation using servo parameter values associated with each corresponding group; and

selecting a parameter value group having a best servo performance quantity.

2. The method, as claimed in claim 1, wherein:

said step of generating a second set of parameter value groups includes selecting at least one parameter value group from said first set of parameter value groups for genetic manipulation.

3. The method, as claimed in claim 2, wherein:

said at least one parameter value group is selected based on a servo performance quantity associated with said at least one parameter value group.

4. The method, as claimed in claim 2, wherein:

said step of generating a second set of parameter value groups includes performing at least one genetic operation using said at least one parameter value group.

5. The method, as claimed in claim 4, wherein:

said at least one genetic operation includes one or more of the following;

a crossover operation, a mutation operation, a dominance operation, and a genetic edge recombination operation.

6. The method, as claimed in claim 1, wherein:

said step of generating an initial set of parameter value groups includes defining value ranges for each of said plurality of servo parameters.

7. The method, as claimed in claim 6, wherein:

said step of generating an initial set of parameter value groups includes randomly generating servo parameter values within said defined value ranges.

8. The method, as claimed in claim 1, wherein:

said step of first determining includes measuring a transducer position error.

9. The method, as claimed in claim 1, wherein:

said step of first determining includes measuring a transducer velocity error.

10. A method for use in tuning servo parameter values in a disk drive, comprising:

providing a servo control system having a plurality of variable parameters, said servo control system having a multitude of possible parameter value combinations for performing a seek operation in the disk drive, each of said parameter value combinations including one parameter value for each of said plurality of variable parameters;

selecting a subset of said multitude of possible parameter value combinations as an initial population of parameter value combinations;

determining a fitness value for each of said parameter value combinations in said initial population by performing a seek operation in the disk drive, said fitness value indicating an ability of a parameter value combination to accurately perform said predetermined servo operation;

choosing at least one of said parameter value combinations in said initial population for reproduction based on fitness value;

genetically manipulating said at least one parameter value combination to generate a new population of parameter value combinations; and

determining a fitness value for each of said parameter value combinations in said new population.

11. The method, as claimed in claim 10, further comprising:

choosing a parameter value combination having a best fitness value when at least one of said parameter value combinations in said new population meets a predetermined fitness criterion.

12. The method, as claimed in claim 10, further comprising:

second choosing at least one parameter value combination from a present population of parameter value combinations for reproduction based on fitness value;

second genetically manipulating said at least one parameter value combination chosen in said second choosing step to generate a subsequent population of parameter value combinations;

second determining a fitness value for each of said parameter value combinations in said subsequent population; and

repeating said steps of second choosing, second genetically manipulating, and second determining until a predetermined criterion is satisfied.

13. The method, as claimed in claim 12, wherein:

said predetermined criterion includes generation of a predetermined number of populations.

14. The method, as claimed in claim 12, wherein:

said predetermined criterion includes at least one of said parameter value combinations meeting a predetermined fitness criterion.

15. The method, as claimed in claim 10, wherein:

said step of determining a fitness value for each of said parameter value combinations in said initial population includes performing said predetermined servo operation using servo parameter values associated with a first parameter value combination and measuring at least one resulting servo performance characteristic.

16. A disk drive comprising:

a data storage disk having a plurality of substantially concentric tracks and a plurality of servo sectors within each track;

a spin motor for rotating said data storage disk about an axis;

a transducer for use in transferring data between a track of said data storage disk and an exterior environment;

an actuator arm assembly coupled to said transducer for use in moving said transducer to a desired track of said data storage disk to perform a data transfer with the desired track, said actuator arm assembly including an actuator arm for supporting said transducer and a motor unit for controllably moving said actuator arm in response to a control signal applied to said motor unit;

a servo control unit coupled to said motor unit for use in generating said control signal, said servo control unit having a plurality of variable parameters that affect the generation of said control signal and thus impact servo performance in said disk drive; and

a servo parameter determination subsystem for determining values for said plurality of variable parameters of said servo control unit, said servo parameter determination subsystem including means for implementing a genetic optimization process within said disk drive to adaptively determine parameter values using an iterative process of data manipulation,

wherein said servo control unit includes a servo control loop for use in performing seek operations within said disk drive, said servo control loop including a first input for receiving seek control values, wherein said servo parameter determination subsystem is operative for determining seek control values for delivery to said input.

17. The disk drive, as claimed in claim 16, wherein:

said servo parameter determination subsystem includes means for monitoring servo performance within said disk drive and means for initiating a genetic optimization procedure when servo performance drops below a predetermined level.

18. The disk drive, as claimed in claim 16, wherein:

said means for implementing a genetic optimization process includes means for determining fitness values for individual parameter value combinations and means for selecting parameter value combinations for reproduction based on said fitness values.

19. A method for tuning servo parameters for use in a seek servo control system within a disk drive, said method comprising the steps of:

providing a disk drive;

determining a first set of servo parameter values for said disk drive using a genetic optimization process, said first set of servo parameter values for use in performing seek operations within a first radial region on a disk surface within said disk drive;

storing said first set of servo parameter values within a memory of said disk drive;

determining a second set of servo parameter values for said disk drive using said genetic optimization process, said second set of servo parameter values for use in performing seek operations within a second radial region on said disk surface, wherein said second radial region is different from said first radial region; and

storing said second set of servo parameter values within said memory of said disk drive.

20. The method claimed in claim 19, further comprising:

determining other sets of servo parameter values for said disk drive using said genetic optimization process, said other sets of servo parameter values for use in performing seek operations within other radial regions on said disk surface, wherein said other radial regions are different from said first and second radial regions; and

storing said other sets of servo parameter values within said memory of said disk drive.

21. The method claimed in claim 19, wherein:

said step of determining a first set of servo parameter values includes generating a position mode table for use during a position mode seek operation.

22. The method claimed in claim 19, wherein said genetic optimization process includes:

generating an initial population of individuals, each of said individuals in said initial population including a plurality of servo parameter values;

determining a fitness value for each individual in said initial population of individuals;

generating a second population of individuals using said initial population of individuals and corresponding fitness values; and

determining a fitness value for each individual in said second population of individuals.

23. The method claimed in claim 22, wherein:

said step of generating a second population of individuals includes selecting individuals from said first population of individuals based on corresponding fitness values and performing genetic operations on said selected individuals.

24. The method claimed in claim 22, further comprising the step of selecting an individual having an optimal fitness value.

25. A method for tuning seek servo parameters of a disk drive, the method comprising the steps of:

providing a disk drive having a plurality of seek servo parameters; and

tuning said seek servo parameters using a genetic process.

26. The method of claim 25, wherein at least one of the plurality of seek servo parameters is a feed forward parameter.

27. The method of claim 25, wherein at least one of the plurality of seek servo parameter values is a position-to-go parameter.

28. A method comprising the steps of:

providing a disk drive having position mode tables for performing position mode seek operations, said position mode tables including adjustable parameters; and

,

tuning said adjustable parameters using a genetic process.

29. The method of claim 28, wherein at least one of the adjustable parameters is a feed forward parameter.

30. The method of claim 30, wherein at least one of the adjustable parameters is a position-to-go parameter.