Method and apparatus for single written-in Repeatable Run-Out correction function used in multi-stage actuation control of hard disk drive

RRO corrector function is formulated to partition the contribution of micro-actuator control from the other voice coil assembly contributions. Single stage actuation is supported by zeroing the micro-actuator control queue, otherwise multi-stage actuation is supported. The multi-stage actuation may include dual stage actuation and in some embodiments triple stage actuation. Triple stage further partitions RRO corrector function for the contribution of the second micro-actuator. Method of initializing an assembled hard disk drive creates hard disk drive as product, using the written-in parameter list for track on the disk surface to recreate the RRO corrector as RRO corrector filter using queues updated by NRRO corrector.

TECHNICAL FIELD

This invention relates to hard disk drives, in particular, to apparatus and methods for controlling Repeatable Run-Out deviations in positioning a slider above a disk surface in a hard disk drive in a uniform manner supporting single stage and multi-stage actuation.

BACKGROUND OF THE INVENTION

Contemporary hard disk drives include an actuator assembly pivoting through an actuator pivot to position one or more read-write heads, embedded in sliders, each over a disk surface. The data stored on the disk surface is typically arranged in concentric tracks. To access the data of a track, a servo controller first positions the read-write head by electrically stimulating the voice coil motor, which couples through the voice coil and an actuator arm to move a head gimbal assembly in lateral positioning the slider close to the track. Once the read-write head is close to the track, the servo controller typically enters an operational mode known herein as track following. It is during track following mode that the read-write head is used to access the data stored on the track.

Micro-actuators provide a second actuation stage for lateral positioning the read-write head during track following mode. They often use an electrostatic effect and/or a piezoelectric effect to rapidly make fine position changes. They have doubled the bandwidth of servo controllers and are believed essential for high capacity hard disk drives from hereon. To minimize Repeatable Run-Out errors, a correction function is written onto the disk surface and used to correct the repeatable errors. With the development of micro-actuators, servo controllers have had a need to support both single stage actuation using just the voice coil motor, and dual stage actuation also using the micro-actuator. However, there are several problems the inventors have encountered during their work with controlling the positioning of sliders above a disk surface in hard disk drives. Straightforward approaches to these correction functions leads to storing two corrector functions for each track, doubling the storage overhead for each track on the disk surface. One of the corrector functions works with the single stage actuator mode and the other works with the dual stage actuator mode of the servo controller. There is another, trickier problem, having to do with the possibility of injecting discontinuities caused by the differences between these corrector functions when the servo controller switches between single and dual stage actuation.

What is needed are corrector functions for Repeatable Run-Out which require nearly the same storage overhead as functions used in single stage actuator hard disk drives, which seamlessly support the servo controller in single stage and multi-stage actuator modes. What is needed are hard disk drives storing these functions for tracks on their disk surfaces incorporating these advantages.

SUMMARY OF THE INVENTION

The invention minimizes the Repeatable Run-Out (RRO) component of the deviation statistics of the Position Error Signal (PES) particularly when the hard disk drive is following a track on a disk surface, known hereafter as track following mode. There are two typical components of PES deviations. The first component is often referred to as the Repeatable Run-Out (RRO), which repeats itself every time a track is followed. Non-Repeatable Run-Out (NRRO), which does not repeat itself.

There are several situations in which the ability to switch between single stage and dual stage actuation is preferred. Single stage actuator is preferred occurs when a micro-actuator fails. It is preferred that the servo-controller be able to readily return to using single stage actuation once the micro-actuator's failure has been recognized. By way of another example, during the seeking of a track, the voice coil motor may be used by itself to move the slider across what may well be thousands of tracks on a disk surface. Once close, the hard disk drive enters track following mode, and use of both the voce coil motor and the micro-actuator to laterally position the slider to follow the track may be preferred.

The invention provides an efficient approach to correcting the RRO of the track as written onto the disk surface during the initialization of an assembled hard disk drive, which is one of the last stages in manufacturing a hard disk drive by partitioning the RRO corrector filter into calculating a voice coil assembly corrector value and a micro-actuator control corrector value. Only the micro-actuator control corrector value is affected by the actuation mode. When the hard disk drive is in single stage actuation mode, the micro-actuator is turned off, and within a short time, the micro-actuator control corrector value is zero. When in dual stage actuation, the micro-actuator is active and the micro-actuator corrector value tends to be non-zero.

A result of reducing the RRO of the track is that this minimizes the Track Mis-Registration of the track during normal access operations. The approach taken is to write in RRO statistics that readily work in both single stage and dual stage actuator modes, allowing the servo controller to switch between single and dual stage actuator mode seamlessly as needed.

The invention includes a method of initializing a disk surface included in a disk in an assembled hard disk drive using a multi-stage actuator mechanism to laterally position a read-write head near a track on the disk surface to create the written-in parameter list of the Repeatable Run-Out (RRO) correction function for use in all actuation modes of the track.

The parameters of the RRO corrector function, include at least one parameter for the voice coil motor control contribution, at least one parameter for the voice coil motor plant contribution, and at least one parameter for the micro-actuator control contribution.

This method may be preferably performed for each of the tracks used for data access on the disk surface. The second disk surface included in the disk may be used for data access, and the method may further include for each track used for data access on the second surface, performing the operations of the method for that track.

The hard disk drive include the disk surface containing the written-in RRO corrector parameter list is a product of this initialization process.

An embedded circuit included in the assembled hard disk drive may implement this method. The embedded circuit may include a servo computer accessibly coupled to a servo memory and directed by a burn-in program system, comprising program steps residing in the servo memory. The burn-in program system may include program steps for each step of the method.

The invention includes a method of using the written-in RRO corrector parameter list in the hard disk drive. The method includes the following. Acquiring the written-in RRO corrector parameter list for the track from the disk surface to recreate the voice coil motor control contribution, the voice coil motor plant contribution, and the micro-actuator control contribution, each for the track used for data access on the disk surface. Controlling actuation of the hard disk drive using the RRO corrector function for the track, based upon the voice coil motor control contribution, the voice coil motor plant contribution, and the micro-actuator control contribution.

The method of use may further include following the track in single stage actuation mode and/or dual stage actuation mode. Following the track in single stage actuation mode may occur when the micro-actuator is damaged.

The hard disk drive implementing the invention's method of using the written-in RRO corrector parameter list may preferably include the following. A servo controller driving a micro-actuator to laterally position a slider near the track on the disk surface to update the micro-actuator control queue, and the servo controller driving the voice coil motor to laterally position the slider close to the track on the disk surface to update the voice coil motor control queue and the voice coil motor plant queue.

The servo controller may further include a servo computer accessibly coupled to a servo memory and directed by a servo program system, including program steps residing in the servo memory. The servo program system may include Acquiring the written-in RRO corrector parameter list for the track from the disk surface to recreate the voice coil motor control contribution, the voice coil motor plant contribution, and the micro-actuator control contribution, each for the track used for data access on the disk surface. Controlling actuation of the hard disk drive using the RRO corrector function for the track, based upon the voice coil motor control contribution, the voice coil motor plant contribution, and the micro-actuator control contribution, as discussed above.

In the method of initializing, determining the micro-actuator control contribution may further include determining the micro-actuator control contribution and the micro-actuator plant contribution to the RRO corrector function of the track on the disk surface. The parameters of the RRO corrector function, further include at least one parameter for the micro-actuator plant contribution.

The hard disk drive may include a second micro-actuator further contributing to the lateral position of the read-write head to the track on the disk surface. The parameters of the RRO corrector function for the track on the disk surface, further include: at least one parameter for a second micro-actuator control contribution, with the methods of initialing and use being altered accordingly.

This hard disk drive operates in the single stage actuation mode when the micro-actuator control queue is updated with zero and the second micro-actuator control queue is updated with zero. The hard disk drive operates in the dual stage actuation mode when one of the micro-actuator control queue and the second micro-actuator control queue is updated with zero. And the hard disk drive operates in the triple stage actuation mode when both of the micro-actuator control queue and the second micro-actuator control queue are updated with non-zero.

As used herein the term micro-actuator refers to a micro-actuator assembly which couples to the slider to aid in positioning its read-write head near the track on the disk surface, or to a micro-actuator embedded in the slider altering the position of-its read-write head. An example of a micro-actuator embedded in the slider includes the vertical micro-actuator embedded in the slider to alter the vertical position of the read-write head. While this invention is primarily focused on the lateral positioning issues, but is readily applicable to vertical position as well.

DETAILED DESCRIPTION

This invention relates to hard disk drives, in particular, to apparatus and methods for controlling Repeatable Run-Out deviations in positioning a slider above a disk surface in a hard disk drive in a uniform manner supporting single stage and multi-stage actuation.

The invention minimizes the Repeatable Run-Out (RRO) component of the deviation statistics of the Position Error Signal (PES) particularly when the hard disk drive is following a track on the disk surface, known hereafter as track following mode. There are two typical components of PES deviations. The first component is often referred to as the Repeatable Run-Out (RRO), which repeats itself every time a track is followed. Non-Repeatable Run-Out (NRRO), which does not repeat itself every time the track is followed.

There are several situations in which the ability to switch between single stage and dual stage actuation is preferred. Single stage actuator is preferred occurs when a micro-actuator fails. It is preferred that the servo-controller be able to readily return to using single stage actuation once the micro-actuator's failure has been recognized. By way of another example, during the seeking of a track, the voice coil motor may be used by itself to move the slider across what may well be thousands of tracks on a disk surface. Once close, the hard disk drive enters track following mode, and use of both the voce coil motor and the micro-actuator to laterally position the slider to follow the track may be preferred.

The invention provides an efficient approach to correcting the RRO of the track as written onto the disk surface during the initialization of an assembled hard disk drive, which is one of the last stages in manufacturing a hard disk drive. A result of reducing the RRO of the track is that this minimizes the Track Mis-Registration of the track during normal access operations. The approach taken is to write in RRO statistics that readily work in both single stage and dual stage actuator modes, allowing the servo controller to switch between single and dual stage actuator mode seamlessly as needed.

The invention includes a method of initializing a disk surface120-1included in a disk12in an assembled hard disk drive9using a multi-stage actuator mechanism to laterally position a read-write head90near a track122on the disk surface to create the written-in parameter list of the Repeatable Run-Out (RRO) correction function for use in all actuation modes of the track as shown inFIGS. 1 to 4,6and8A. The multi-stage actuator mechanism includes a voice coil motor18and a micro-actuator80, both aiding in controlling the lateral position LP of the read-write head near the track. The invention formats a raw disk12before, to create the initialized disk surface120-1on the disk12in the hard disk drive10, which is the product of this process.

Some of the following figures show flowcharts of at least one method of the invention, possessing arrows with reference numbers. These arrows will signify of flow of control and sometimes data supporting implementations including at least one program operation or program thread executing upon a computer, inferential links in an inferential engine, state transitions in a finite state machine, and dominant learned responses within a neural network.

The operation of starting a flowchart refers to at least one of the following. Entering a subroutine in a macro instruction sequence in a computer. Entering into a deeper node of an inferential graph. Directing a state transition in a finite state machine, possibly while pushing a return state. And triggering a collection of neurons in a neural network.

The operation of termination in a flowchart refers to at least one or more of the following. The completion of those operations, which may result in a subroutine return, traversal of a higher node in an inferential graph, popping of a previously stored state in a finite state machine, return to dormancy of the firing neurons of the neural network.

A computer as used herein will include, but is not limited to an instruction processor. The instruction processor includes at least one instruction processing element and at least one data processing element, each data processing element controlled by at least one instruction processing element. By way of example, a computer may include a general purpose computer and/or a Digital Signal Processor (DSP). The general purpose computer and/or DSP may directly implement fixed point and/or floating point arithmetic.

An embedded circuit500included in the assembled hard disk drive9may implement this method. The assembled disk drive may further include a servo controller600implementing this process and included in the embedded circuit. The embedded circuit, and preferably the servo controller, may preferably include a servo computer610accessibly coupled612to a servo memory620and directed by a burn-in program system800, comprising program steps residing in the servo memory. The burn-in program system may include program steps for each step of the method. The method includes the following operations, which are shown inFIG. 5Bfor the track as implemented by operation804of the burn-in program system inFIG. 5A. Operation810supports determining a voice coil motor control contribution B and a voice coil motor plant contribution B to a Repeatable Run-Out (RRO) corrector function Wc320for the track on the disk surface120-1. Operation812supports determine a micro-actuator control contribution F to the RRO corrector function for the track. Operation814supports writing the parameters of the RRO corrector function for the track to the disk surface to create a written-in parameter list320L for the RRO corrector function Wc3220on the disk surface included in a hard disk drive10.

The invention operates by generating a Repeatable Run-Out (RRO) Corrector Function Wc922for a track122on the disk surface120-1, and recording the parameters of this function as the written-in parameter list320L for the track on the disk surface120-1, which when completed for the tracks used for data on the disk surface, yields at least one side of the prepared disk12in the hard disk drive10. By way of example,FIG. 5Ashows the following operations as details of the burn-in program system800, and the invention's method of initializing the raw disk12before. Operation802supports setting the track to a first track used for data access. Operation804supports determining and writing the parameters of an RRO corrector function for the track seamlessly supporting both single stage and multi-stage actuation. Operation806supports incrementing the track. Operation808supports testing whether the track is less than or equal to the last track used for data access. If the track is less than or equal to the last track, the servo computer610is directed by the burn-in program system to proceed to operation804, otherwise it proceeds to exit.

By way of example, consider the hard disk drive10supporting single stage actuation using just the voice coil motor18to laterally position LP a slider90, as well as dual stage actuation further using the micro-actuator assembly80mechanically coupled to the slider as shown inFIGS. 6 and 8A. The written-in parameter list320L provides for recreating the RRO corrector function Wc320used by the servo controller600support both single stage actuation as well as dual stage actuation, minimizing the Repeatable Run-Out (RRO) component of the deviation statistics of the Position Error Signal (PES) when following the track122on the disk surface120-1, particularly in track following mode. The written-in parameter list includes the control parameters stored on part of the disk surface reserved for internal use and typically loaded into the servo controller600when the hard disk drive10powers up or is reset.

Before going on to further discuss the details of the invention, a brief discussion of prior art RRO corrector functions in general, and the specific elements of the invention's RRO corrector function will now be described. Typically, there are two prior art approaches employed to calculate the written-in RRO corrector Wc320as shown inFIGS. 2A and 2B.

The first typical approach uses the PESpre310and servo Error Sensitivity Function (ESF) to calculate the written-in RRO as shown inFIG. 2A. This approach requires two sets of Error Sensitivity Functions, one for single stage and the other for dual stage actuation, doubling the memory overhead on the disk surface. The total deviation Dev342is defined by
Dev=drro+dnrro(0.1)

The written in RRO corrector function Wc320is defined by

is the error sensitivity function associated with the servo loop including the dynamic controller C320providing the control variable U302to the Plant P330to create the position in time Yt340. There is an additional problem with this approach, the Signal to Noise Ratio (SNR) of the dual stage error sensitivity function will always be smaller than the single stage error sensitivity function, since the dual stage error sensitivity function would have the form

where Pmarelates to the micro-actuator Plant Pma330and Cmarelates to the micro-actuator controller Cma322, as shown inFIG. 2B.

The second approach uses PES and the control effort of the voice coil motor18to calculate the written-in RRO. This typical approach suffers from having only one control effort input, making it unacceptable for dual stage actuation, since the micro-actuator assembly80is also contributing to the lateral position LP. Here the written-in RRO corrector function Wc320is defined by
wc={circumflex over (d)}rro=(1+PC)·PESpost=PESpost+P·u(0.5)

This second typical approach also suffers from requiring twice the storage overhead as the first approach, because two separate written-in RRO corrector functions must be stored, one for single stage actuation and the other dual stage actuation.

The invention uses a modification of the second typical approach based uponFIG. 2B, where the written-in RRO corrector function Wc320defined by

The inventors have found that this expression of the written-in RRO corrector function Wc320has several advantages. It requires only slightly more memory than the second approach for single stage actuation, and the conversion between single and dual stage actuation is controlled by uMA. In single stage actuation, uMA[k]=0 and in dual stage actuation, uMA[k]≠0 .

By way of example, an adequate model of the micro-actuator plant may have constant gain, making PMAa constant, and affording a model of the micro-actuator plant output Yma336by
yMA[k]=F0uMA[k](0.7)

It may further be preferred to model the voice coil motor18Plant Pc330by the transfer function

leading to predicting the voice coil motor plant output Yp334by
yP[k]=b0uC[k]+b1uC[k−1]−a1yP[k−1]−a2[k−2]  (0.9)

Thus requiring the storage of the parameters of Wc320as
WC≡{F0, a1, a2, b0, b1}(0.10)

In general, embodiments of the invention will use a micro-actuator transfer function Pma

Which expresses the micro-actuator plant output Yma336by

And in general the voice coil motor plant Pc330is often modeled by the transfer function

Which models the voice coil motor18Plant Pc330by its output Yp334as

The RRO corrector function Wc320may be implemented as the RRO Corrector filter320F generating the RRO micro-actuator control corrector value WmaVal 320 ma which is added to the RRO voice coil assembly corrector value WvcaVal 320 vca to create the RRO corrector value WcVal 320V ofFIG. 3. This is mathematically written as
wCval[k]≡wVCAval[k]+wMAval[k]  (0.16)

The RRO micro-actuator control corrector value WmaVal 320 ma may be preferably defined by

The RRO voice coil assembly corrector value WvcaVal 320 vca may be defined by
wVCAval[k]≡wVcmCval[k]+wVcmPval[k]+wMapval[k](0.18)

showing the RRO voice coil assembly corrector value WvcaVal 320 vca denoted by wVCAval[k] as the RRO voice coil motor control value denoted by wVcmCval[k] added to the RRO voice coil motor plant value denoted by wVcmPval[k] and added to the RRO micro-actuator plant corrector value denoted by wMaPval[k].

The RRO voice coil motor control value denoted by wVcmCval[k] is defined as the voice coil motor control contribution B≡[b0. . . bNB] acting on the voice coil motor control queue Uc302denoted by UC≡[uC[k] . . . uC[k−NB]]

The RRO voice coil motor control value denoted by wVcmCval[k] is defined as voice coil motor plant contribution denoted by A≡[a1. . . aNA] acting on the voice coil plant queue Yp334denoted by YC≡[yC[k−1] . . . yC[k−NA]]

The RRO micro-actuator plant corrector value denoted by wMaPval[k] is defined as the micro-actuator plant contribution G≡[G1. . . GNG] acting on the micro-actuator plant queue Yma336denoted by YMA≡[yMA[k−1] . . . yMA[k−NG]]

This single written-in Repeatable Run-Out corrector function Wc320has a general advantage of supporting both single stage and dual stage actuation with the same model, with the transition from dual stage to single stage actuation being handles by setting successive values of uMA[k] to zero. So that at the first time step
UMA=[0uMA[k−1]. . . uMA[k−NF]]  (0.22)

and so on, showing the dampening effect, if the higher order terms are significant, of the transition to single stage actuation on the Repeatable Run-Out from the micro-actuator assembly80. When the higher order terms are treated as zero, as in (0.7), then the transition is modeled as instantaneous, with no residual effects.

FIG. 4shows a preferred embodiment of the invention, when NG=0, G(z)=1 and

With the micro-actuator plant output Yma336expressed by

The RRO corrector function Wc320may be implemented as the RRO Corrector filter320F generating the RRO micro-actuator control corrector value WmaVal 320 ma which is added to the RRO voice coil assembly corrector value WvcaVal 320 vca to create the RRO corrector value WcVal 320V ofFIG. 3. This is mathematically written as
wCval[k]≡wVCAval[k]+wMAval[k]  (0.27)

The RRO voice coil motor control corrector value WmaVal 320 ma may be preferably defined by as before by (0.17), again including the micro-actuator control contribution F≡[F0. . . FNF] applied to a micro-actuator control queue Uma304denoted by UMA≡[uMA[0] . . . uMA[NF]] to create the RRO micro-actuator control corrector value.

In these embodiments, contribution of the micro-actuator plant is negligible making the RRO voice coil assembly corrector value WvcaVal 320 vca preferably defined by
wVCAval[k]≡wVcmPval[k]+wVcmPval[k]  (0.28)

showing the RRO voice coil assembly corrector value WvcaVal 320 vca denoted by wVCAval[k] as the RRO voice coil motor control value denoted by wVcmCval[k] added to the RRO voice coil motor plant value denoted by wVcmPval[k].

The parameters of the RRO corrector function, include at least one parameter for the voice coil motor control contribution B, at least one parameter for the voice coil motor plant contribution A, and at least one parameter for the micro-actuator control contribution F as shown inFIG. 4.

This method may be preferably performed for each of the tracks used for data access on the disk surface. The second disk surface included in the disk may be used for data access, and the method may further include for each track used for data access on the second surface, performing the operations of the method for that track.

The invention includes a method of using the written-in RRO corrector parameter list320L in the hard disk drive10. The hard disk drive implementing the invention's method of using the written-in RRO corrector parameter list may preferably include the following shown inFIGS. 3 and 4. A servo controller600driving a micro-actuator80to laterally position LP a slider90near the track122on the disk surface120-1to update the micro-actuator control queue Uma304, and the servo controller driving the voice coil motor18to laterally position the slider close to the track on the disk surface to update the voice coil motor control queue Uc302and the voice coil motor plant queue Yp334.

The servo controller600may further include a servo computer610accessibly coupled612to a servo memory620and directed by a servo program system1000, including program steps residing in the servo memory. The servo program system implement the method of using the written-in RRO corrector parameter list320by operations as shown inFIG. 7A. Operation1002supports acquiring the written-in RRO corrector parameter list320L for the track122from the disk surface120-1to recreate the voice coil motor control contribution B, the voice coil motor plant contribution A, and the micro-actuator control contribution F, each for a track used for data access on the disk surface. Operation1004supports controlling actuation of the hard disk drive10using the RRO corrector function Wc320for the track, based upon the voice coil motor control contribution B, the voice coil motor plant contribution A, and the micro-actuator control contribution F.

Operation1004controlling actuation preferably includes the following shown inFIG. 7B. Operation1010supports calculating the RRO corrector filter based upon the micro-actuator control contribution F applied to a micro-actuator control queue Uma304, said voice coil motor control contribution B applied to a voice coil motor control queue Uc302, said voice coil motor plant contribution A applied to a voice coil motor plant queue Yp334, to create the RRO micro-actuator control corrector value WmaVal 320 ma and the RRO voice coil assembly corrector value WvcaVal 320 vca. Operation1012supports calculating the RRO corrector value WcVal320as the RRO micro-actuator control corrector value added to the RRO voice coil assembly corrector value. Operation1014supports calculating the Position Error Signal (PES) post-RRO as the PES pre-RRO minus the RRO corrector value. And operation1016supports performing Non-Repeatable Run-Out (NRRO) control based upon the PES post RRO and updating the micro-actuator control queue, the voice coil motor control queue, and the voice coil motor plant queue.

The hard disk drive10operates in a single stage actuation mode when the micro-actuator control queue Uma is updated with a zero as discussed with regards to equations (0.22) and (0.23). Otherwise the hard disk drive operates in a dual stage actuation mode.

Operation1010calculating the RRO corrector filter Wc320F ofFIG. 7Bmay further include the operations ofFIG. 7C. Operation1020supports calculating the micro-actuator control contribution F applied to the micro-actuator control queue Uma304to create the RRO micro-actuator control corrector value WmaVal 320 ma denoted by wMAval[k] and discussed regarding equation (0.17). Operation1022calculating the voice coil motor control contribution A applied to the voice coil motor control queue Uc302and the voice coil motor plant contribution B applied to the voice coil motor plant queue Yp334the RRO voice coil assembly corrector value WvcaVal 320 vca may further include the operations ofFIG. 7D.

Operation1030supports calculating the voice coil motor control contribution B applied to a voice coil motor control queue Uc302to create the RRO voice coil motor control corrector value denoted by wVcmCval[k] and discussed regarding equation (0.19). Operation.1032supports calculating the voice coil motor plant contribution A applied to a voice coil motor plant queue Yp334to create the RRO voice coil motor plant corrector value denoted by wVcmPval[k] and discussed regarding equation (0.20). And operation1034calculating the RRO voice coil assembly corrector value WvcaVal 320 vca as the RRO voice coil motor control corrector value added to the RRO voice coil motor plant corrector value.

The method of use as shown in the servo program system1000may further include following the track122in single stage actuation mode and/or dual stage actuation mode. Following the track in single stage actuation mode may preferably occur when the micro-actuator80is damaged.

The written-in parameter list320L may preferably include the micro-actuator control contribution F, the voice coil motor control contribution B, and the voice coil motor plant contribution A, as shown inFIG. 5D.

The method of initializing as shown in the burn-in program system800, shows operation812determining the micro-actuator control contribution inFIG. 5B, and may further include operation820, which further supports determining the micro-actuator plant contribution G to the RRO corrector function Wc of the track122on the disk surface120-1inFIG. 5C. The parameters of the RRO corrector function, in particular the written-in parameter list320L may further include at least one parameter for the micro-actuator plant contribution G as shown inFIG. 5E.

The method of using the written-in RRO corrector parameter list320L discussed herein in terms of the servo program system1000, in particular operation1022ofFIGS. 7B and 7D, may further include operation1036calculating the micro-actuator plant contribution G applied to a micro-actuator plant queue Yma336to further create the RRO voice coil assembly corrector value WvcaVal 320 vca as shown inFIG. 7E.

Operation1036creating the RRO voice coil assembly corrector value WvcaVal 320 vca may further include the operations ofFIG. 7F. Operation1040supports calculating the micro-actuator plant contribution G applied to a micro-actuator plant queue Yma336to create the RRO micro-actuator plant corrector value WmaPVal denoted by wMaPval[k] and discussed with regards equation (0.21). Operation1042supports calculating the RRO voice coil motor assembly corrector value added to the RRO voice coil motor plant corrector value added to the RRO voice coil assembly corrector value denoted by wVCAval[k], and consistent with (0.18).

As used herein the term micro-actuator refers to a micro-actuator assembly80which couples to the slider90to aid in positioning its read-write head90near the track122on the disk surface120-1as shown inFIGS. 1,6,8B to9B,11,13A to15and19or to a micro-actuator80A embedded in the slider altering the position of its read-write head as shown inFIGS. 15 and 19. An example of a micro-actuator embedded in the slider includes the vertical micro-actuator98embedded in the slider to alter the vertical position VP of the read-write head. While this invention is primarily focused on the lateral positioning LP issues, it is readily applicable to vertical position as well.

The hard disk drive10may further include a second micro-actuator80A further contributing to the lateral position LP of the read-write head90near the track122on the disk surface120-1as shown inFIGS. 15 and 19. The parameters of the RRO corrector function Wc320for the track on the disk surface, further include: at least one parameter for a second micro-actuator control contribution L. The dynamics and control issues will now be discussed, which will be followed by further discussion of the invention and its embodiments.

In general, these embodiments of the invention will use a second micro-actuator transfer function Pma2

Which expresses the second micro-actuator plant output Yma2340by

The RRO corrector function Wc320may again be implemented as the RRO Corrector filter320F generating the RRO micro-actuator control corrector value WmaVal 320 ma and the second RRO micro-actuator control corrector value Wma2 Val 320 ma2 which are added to the RRO voice coil assembly corrector value WvcaVal 320 vca to create the RRO corrector value WcVal 320V ofFIGS. 18A and 18B. This is mathematically written as
wCval[k]≡wVCAval[k]+wMAval[k]+wMA2val[k]  (0.32)

The second RRO micro-actuator control corrector value Wma2 Val 320 ma2 may be preferably defined by

which includes the second micro-actuator control contribution L≡[L0. . . LNL] applied to a second micro-actuator control queue Uma2304-2denoted by UMA2≡[uMA2[0] . . . uMA2[NL]] to create the second RRO micro-actuator control corrector value Wma2 Val 320 ma2.

The RRO voice coil assembly corrector value WvcaVal 320 vca when both micro-actuators have significant plant contributions, as shown inFIG. 18A, may be redefined for dual micro-actuators by
wVCAval[k]≡wVcmCval[k]+wVcmPval[k]+wMaPval[k]+wMa2Pval[k]  (0.34)

showing the RRO voice coil assembly corrector value WvcaVal 320 vca denoted by wVCAval[k] as the RRO voice coil motor control value denoted by wVcmCval[k] added to the RRO voice coil motor plant value denoted by wVcmPval[k], added to the RRO micro-actuator plant corrector value denoted by wMaPval[k], and further added to the second RRO micro-actuator plant corrector value denoted by wMa2Pval[k].

When the second micro-actuator plant contribution is negligible, NM=0, the RRO voice coil assembly corrector value WvcaVal 320 vca may be calculated as indicated in equation (0.18). When the micro-actuator plant contribution is negligible as well, the RRO voice coil assembly corrector value WvcaVal 320 vca may be calculated as indicated in equation (0.28).

When only the micro-actuator plant contribution is negligible, the RRO voice coil assembly corrector value WvcaVal 320 vca may be calculated as
wVCAval[k]≡wVcmCval[k]+wVcmPval[k]+wMa2Pval[k]  (0.35)

The second RRO micro-actuator plant corrector value denoted by wMa2Pval[k] is defined as the second micro-actuator plant contribution M≡[M1. . . MNM] acting on the second micro-actuator plant queue Yma336-2denoted by YMA2≡[yMA2[k−1] . . . yMA2[k−NM]]

This single written-in Repeatable Run-Out corrector function Wc320has a general advantage of supporting single, dual, and triple stage actuation with the same model, with the transition from triple stage to either dual stage and that dual stage to single stage actuation being handled by setting successive values of uMA[k] and/or uMA2[k] to zero. This hard disk drive10supports triple stage actuation when the voice coil motor18along with both the micro-actuator80and the second micro-actuator80A are actively controlled.

There are two dual stage actuation modes for the hard disk drive10. The first turns off the second micro-actuator80A and the RRO corrector function handles this by setting successive values of uMA2[k] to zero, and the second turns off the micro-actuator80, which the RRO corrector function handles by setting successive values of uMA[k] to zero.

Single stage actuation involves both the micro-actuator80and the second micro-actuator80A being turned off, which is handled by the RRO corrector function by setting successive values of both uMA[k] and uMA2[k] to zero.

Setting successive values of uMA2[k] to zero preferably means that at the first time step the second micro-actuator control queue Uma2304-2has the state
UMA2=[0uMA2[k−1] . . . uMA2[k−NL]]  (0.37)

and so on, showing the dampening effect, if the higher order terms are significant, of the transition to single stage actuation on the Repeatable Run-Out from the micro-actuator assembly80. When the higher order terms are treated as zero, as in (0.7), then the transition is modeled as instantaneous, with no residual effects.

FIG. 18Bshows a preferred embodiment of the invention, when the second micro-actuator plant contribution is negligible, NM=0, M (z)=1 and

With the second micro-actuator plant output Yma2336-2expressed by

And when the micro-actuator plant contribution is also negligible, NG=0, G(z)=1 and

With the micro-actuator plant output Yma336expressed by

Triple stage actuation support by the RRO corrector function Wc320is preferably implemented as the RRO Corrector filter320F generating the RRO micro-actuator control corrector value WmaVal 320 ma added to the second RRO micro-actuator control corrector value WmaVal 320 ma2 added to the RRO voice coil assembly corrector value WvcaVal 320 vca to create the RRO corrector value WcVal 320V as shown inFIGS. 18A and 18B. This is mathematically written as
wCval[k]≡wVCAval[k]+wMAval[k]+wMA2val[k]  (0.45)

The method of initializing the assembled hard disk drive9ofFIG. 15, which is being discussed in terms of the burn-in program system800, and in particular for operation804ofFIG. 5Adetermining and writing parameters of the RRO corrector function Wc320of the track122on the disk surface120-1may preferably include the operations ofFIG. 16B. Operation814supports determining the second micro-actuator control contribution L to the RRO corrector function. Operation816supports determining the second micro-actuator plant contribution M to the RRO corrector function of the track on the disk surface.

In the method of using the written-in RRO corrector parameter list320L in the hard disk drive10ofFIGS. 18A to 19, acquiring the written-in RRO corrector parameter list may further include acquiring1002the written-in RRO corrector parameter list for the track122from the disk surface120-1to recreate the second micro-actuator control contribution L for the track.

The method of using as implemented by the servo program system1000, in particular operation1004ofFIGS. 7A and 7Bsupporting actuation control using the RRO corrector function Wc320for the track122may further include the operations ofFIG. 20. Operation1040supports calculating based upon the second micro-actuator control contribution L applied to a second micro-actuator control queue Uma304-2to create the RRO second micro-actuator control corrector value Wma2 Val 320 ma as discussed with equation(0.33).

Operation1042supports further calculating the RRO corrector value WcVal 320V as the second RRO micro-actuator control corrector value Wma2 Val 320 am2 added to the RRO micro-actuator control corrector value WmaVal 320 am added to the RRO voice coil assembly corrector value WvcaVal 320 vca as discussed with equation (0.45). Operation1018supports performing the NRRO control by further updating the second micro-actuator control queue Uma304-2.

The slider, and its read-write head may include a read head using a spin valve to read the data on the disk surface, or use a tunneling valve to read the data. The slider may include a vertical micro-actuator for altering the vertical position of the read-write head above the disk surface. The slider may further include the read head providing a read differential signal pair to an amplifier to generate an amplified read signal reported by the slider as a result of the read access of the data on the disk surface. The amplifier may be opposite the air bearing surface, and may be separate from the deformation region, and may further be separate from the vertical micro-actuator.

The slider90may include a vertical micro-actuator98, coupled to a deformation region97including a read-write head94and stimulated by a vertical control signal VcAC providing a potential difference with a first slider power terminal SP1, possibly by heating the deformation region to alter the vertical position Vp of the read-write head over the disk surface120-1in a hard disk drive10as shown inFIGS. 8C and 9A.

The slider90is used to access the data122on the disk surface120-1in a hard disk drive10. The data is typically organized in units known as a track122, which are usually arranged in concentric circles on the disk surface centered about a spindle shaft40and alternatively may be organized as joined spiral tracks. Operating the slider to read access the data on the disk surface includes the read head94-R driving the read differential signal pair r0to read access the data on the disk surface. The read-write head94is formed perpendicular to the air bearing surface92.

The read head94-R may use a spin valve to drive the read differential signal pair as shown inFIG. 10A. As used herein, the spin valve employs a magneto-resistive effect to create an induced sensing current Is between the first shield Shield1and the second shield Shield2. Spin valves have been in use the since the mid1990's.

The read head94-R may use a tunnel valve to drive the read differential signal pair as shown inFIG. 10B. As used herein, a tunnel valve uses a tunneling effect to modulate the sensing current Is perpendicular to the first shield Shield1and the second shield Shield2. Both longitudinally recorded signals as shown inFIG. 10Cand perpendicularly recorded signals shown inFIG. 10Dcan be read by either reader type. Perpendicular versus longitudinal recording relates to the technology of the writer/media pair, not just reader. This difference in bit polarization lead to the announcement of a large increase in data density, a jump of almost two hundred percent in the spring of 2005.

The tunnel valve is used as follows. A pinned magnetic layer is separated from a free ferromagnetic layer by an insulator, and is coupled to a pinning antiferromagnetic layer. The magneto-resistance of the tunnel valve is caused by a change in the tunneling probability, which depends upon the relative magnetic orientation of the two ferromagnetic layers. The sensing current Is, is the result of this tunneling probability. The response of the free ferromagnetic layer to the magnetic field of the bit of the track122of the disk surface120-1, results in a change of electrical resistance through the tunnel valve.

The slider90may further include the read-write head94providing the read-differential signal pair r0to the amplifier96to generate the amplified read signal ar0, as shown inFIG. 13B. The read-write head preferably includes a read head94-R driving the read differential signal pair r0and a write head94-W receiving a write differential signal pair w0. The slider reports the amplified read signal as a result of read access of the data on the disk surface. In most but not necessarily all of the embodiments of the invention's slider, the amplifier is preferably opposite the air bearing surface92. The amplified read signal ar0may be implemented as an amplified read signal pair ar0+- or as a single ended read signal. The vertical micro-actuator98may preferably operate by inducing a strain on the deformation region97as well as any other materials directly coupled to it, making it preferable for the amplifier to be separated from the vertical micro-actuator and the deformation region, as shown inFIGS. 8C,13B, and14A. These embodiments of the invention's slider preferably include a first slider power terminal SP1and a second slider power terminal SP2collectively used to power the amplifier in generating the amplified read signal ar0.

The flexure finger may include a micro-actuator assembly for mechanically coupling to an embodiment of the slider. The flexure finger may include a vertical control signal path providing the vertical control signal to the slider and the heating element. The micro-actuator assembly may aid in lateral positioning, and may further aid in vertical positioning of the read-write head over the data of the disk surface. The micro-actuator assembly may employ a piezoelectric effect and/or an electrostatic effect to aid in positioning the read-write head.

The flexure finger20for the slider90ofFIGS. 9A,6,11, and13B, which preferably contains a micro-actuator assembly80for mechanically coupling to the slider to aid in positioning the slider to access the data122on120-1disk surface of the disk12. The micro-actuator assembly may aid in laterally positioning LP the slider to the disk surface as shown inFIG. 10Aand/or aid in vertically positioning VP the slider as shown inFIG. 6. The flexure finger20may further provide the vertical control signal VcAC and preferably the first lateral control signal82P1as the first slider power terminal SP1to the vertical micro-actuator.

The flexure finger20preferably includes the lateral control signal82and trace paths between the slider for the write differential signal pair w0. The lateral control signal preferably includes the first lateral control signal82P1and the second lateral control signal82P2, as well as the AC lateral control signal82AC. When the slider does not contain an amplifier96, as shown inFIGS. 6,9A and11, the flexure finger further preferably provides trace paths for the read differential signal pair r0.

The micro-actuator assembly80may employ a piezoelectric effect and/or an electrostatic effect to aid in positioning the slider90. First, examples of micro-actuator assemblies employing the piezoelectric effect will be discussed followed by electrostatic effect examples. In several embodiments of the invention the micro-actuator assembly may preferably couple with the head gimbal assembly60through the flexure finger20, as shown inFIGS. 9A,9B,6and13B. The micro-actuator assembly may further couple through the flexure finger to a load beam74to the head gimbal assembly and consequently to the voice coil assembly50.

Examples of micro-actuator assemblies employing the piezoelectric effect are shown inFIGS. 8C and 13A.FIG. 8Cshows a side view of a head gimbal assembly with a micro-actuator assembly80including at least one piezoelectric element PZ1for aiding in laterally positioning LP of the slider90. In certain embodiments, the micro-actuator assembly may consist of one piezoelectric element. The micro-actuator assembly may include the first piezoelectric element and a second piezoelectric element PZ2, both of which may preferably aid in laterally positioning the slider. In certain embodiments, the micro-actuator assembly may be coupled with the slider with a third piezoelectric element PZ3to aid in the vertically positioning the slider above the disk surface120-1.

Examples of the invention using micro-actuator assemblies employing the electrostatic effect are shown inFIGS. 14A and 14Bderived from the Figures of U.S. patent application Ser. No. 10/986,345, which is incorporated herein by reference.FIG. 14Ashows a schematic side view of the micro-actuator assembly80coupling to the flexure finger20via a micro-actuator mounting plate700.FIG. 14Bshows the micro-actuator assembly using an electrostatic micro-actuator assembly2000including a first electrostatic micro-actuator220to aid the laterally positioning LP of the slider90. The electrostatic micro-actuator assembly may further include a second electrostatic micro-actuator520to aid in the vertically positioning VP of the slider.

The first micro-actuator220includes the following. A first pivot spring pair402and408coupling to a first stator230. A second pivot spring pair400and406coupling to a second stator250. A first flexure spring pair410and416, and a second flexure spring pair412and418, coupling to a central movable section300. A pitch spring pair420-422coupling to the central movable section300. The central movable section300includes signal pair paths coupling to the write differential signal pair W0and either the read differential signal pair r0or the amplified read signal ar0of the read-write head94of the slider90.

The bonding block210may electrically couple the read-write head90to the amplified read signal ar0and write differential signal pair W0, and mechanically couples the central movable section300to the slider90with read-write head94embedded on or near the air bearing surface92included in the slider.

The first micro-actuator220aids in laterally positioning LP the slider90, which can be finely controlled to position the read-write head94over a small number of tracks122on the disk surface120-1. This lateral motion is a first mechanical degree of freedom, which results from the first stator230and the second stator250electrostatically interacting with the central movable section300. The first micro-actuator220may act as a lateral comb drive or a transverse comb drive, as is discussed in detail in the incorporated U.S. patent application.

The electrostatic micro-actuator assembly2000may further include a second micro-actuator520including a third stator510and a fourth stator550. Both the third and the fourth stator electostatically interact with the central movable section300. These interactions urge the slider90to move in a second mechanical degree of freedom, aiding in the vertically positioning VP to provide flying height control. The second micro-actuator may act as a vertical comb drive or a torsional drive, as is discussed in detail in the incorporated U.S. patent application. The second micro-actuator may also provide motion sensing, which may indicate collision with the disk surface120-1being accessed.

The central movable section300not only positions the read-write head10, but may act as the conduit for the write differential signal pair w0and in certain embodiments, the first slider power signal SP1and the second slider power signal SP2, as well as the read differential signal pair r0or the amplified read signal ar0. The electrical stimulus of the first micro-actuator220is provided through some of its springs.

The central movable section300may preferably to be at ground potential, and so does not need wires. The read differential signal pair r0, the amplified read signal ar0, the write differential signal pair w0and/or the slider power signals SP1and SP2traces may preferably be routed with flexible traces all the way to the load beam74as shown inFIG. 14A.

The flexure finger20may further provide a read trace path rtp for the amplified read signal ar0, as shown inFIG. 13B. The slider90may further include a first slider power terminal SP1and a second slider power terminal SP2, both electrically coupled to the amplifier96to collectively provide power to generate the amplified read signal ar0. The flexure finger may further include a first power path SP1P electrically coupled to the first slider power terminal SP1and/or a second power path SP2P electrically coupled to the second slider power terminal SP2, which are collectively used to provide electrical power to generate the amplified read signal.

The head gimbal assembly preferably includes the invention's flexure finger coupled to the slider, which further includes the micro-actuator assembly mechanically coupled to the slider and may further include the vertical control signal path electrically coupled to the vertical control signal of the slider. The invention's voice coil assembly includes at least one of the head gimbal assemblies coupled to a head stack. The invention's hard disk drive includes a voice coil assembly, which includes at least one of the head gimbal assemblies.

The head gimbal assembly60may include the flexure finger20coupled with the slider90and a micro-actuator assembly80mechanically coupling to the slider to aid in positioning the slider to access the data122on the disk surface120-1. The micro-actuator assembly may further include a first micro-actuator power terminal82P1and a second micro-actuator power terminal82P2. The head gimbal assembly may further include the first micro-actuator power terminal electrically coupled to the first power path SP1P and/or the second micro-actuator power terminal electrically coupled to the second power path SP2P. Operating the head gimbal assembly may further preferably include operating the micro-actuator assembly to aid in positioning the slider to read access the data on the disk surface, which includes providing electrical power to the micro-actuator assembly.

The head gimbal assembly60may further provide the vertical control signal VcAC to the heating element of the vertical micro-actuator98, as shown inFIGS. 6 and 13B. Operating the head gimbal assembly may further preferably include driving the vertical control signal. The first micro-actuator power terminal82P1may be tied to the first slider power terminal SP1, and both electrically coupled to the first power path SP1P.

The head gimbal assembly60may further include the amplifier96to generate the amplified read signal ar0using the first slider power terminal SP1and the second slider power terminal SP2. The flexure finger20may further contain a read trace path rtp electrically coupled to the amplified read signal ar0, as shown inFIG. 13B. The head gimbal assembly operates as follows when read accessing the data122, preferably organized as the track122, on the disk surface120-1. The slider90reports the amplified read signal ar0as the result of the read access.

The flexure finger20may be coupled to the load beam74as shown inFIGS. 9B and 14A, which may further include the first power path SP1P electrically coupled to a metallic portion of the load beam. In certain embodiments, the metallic portion may be essentially all of the load beam.

In further detail, the head gimbal assembly60includes a base plate72coupled through a hinge70to a load beam74. Often the flexure finger20is coupled to the load beam and the micro-actuator assembly80and slider90are coupled through the flexure finger to the head gimbal assembly. The load beam may preferably electrically couple to the slider to the first slider power terminal SP1, and may further preferably electrically couple to the micro-actuator assembly to form the first power path SP1P.

The invention also includes a voice coil assembly50containing at least one head gimbal assembly60coupled to a head stack54, as shown inFIGS. 6 and 11.

The voice coil assembly50may include more than one head gimbal assembly60coupled to the head stack54. By way of example,FIG. 11shows the voice coil assembly coupled with a second head gimbal assembly60-2, a third head gimbal assembly60-3and a fourth head gimbal assembly60-4. Further, the head stack is shown inFIG. 6including the actuator arm52coupling to the head gimbal assembly. InFIG. 11, the head stack further includes a second actuator arm52-2and a third actuator arm52-3, with the second actuator arm coupled to the second head gimbal assembly60-2and a third head gimbal assembly60-3, and the third actuator arm coupled to the fourth head gimbal assembly604. The second head gimbal assembly includes the second slider90-2, which contains the second read-write head94-2. The third head gimbal assembly includes the third slider90-3, which contains the third read-write head94-3. And the fourth head gimbal assembly includes a fourth slider90-4, which contains the fourth read-write head94-4.

The voice coil assembly50preferably operates as follows: for each of the sliders90included in each of the head gimbal assemblies60of the head stack, when the temperature of the shape memory alloy film of the slider is below the first temperature, the film configures in a first solid phase to the deformation region97to create the vertical position VP of that read-write head above its disk surface. Whenever the temperature of the film of the shape memory alloy is above the first temperature, the film configures in a second solid phase to the deformation region increasing the vertical position of the read-write head above the disk surface.

In certain embodiments where the slider90includes the amplifier96, the slider reports the amplified read signal ar0as the result of the read access to the track122on the disk surface120-1. The flexure finger provides the read trace path rtp for the amplified read signal, as shown inFIG. 8C. The voice coil assembly50may include a main flex circuit200coupled with the flexure finger20, which may further include a preamplifier24electrically coupled to the read trace path rtp in the read-write signal bundle rw to create the read signal25-R based upon the amplified read signal as a result of the read access.

The invention's hard disk drive10, shown inFIGS. 6,8A,9A,11,12,18A,18B and19includes the voice coil assembly50pivotably mounted through the actuator pivot58on a disk base14and arranged for the slider90of the head gimbal assembly60to be laterally positioned LP near the data122for the read-write head94to access the data on the disk surface120-1. The disk12is rotatably coupled to the spindle motor270by the spindle shaft40. The voice coil assembly is electrically coupled to the embedded circuit500.

The embedded circuit500may preferably include the servo controller600, as shown inFIG. 6, which may further include a servo computer610accessibly coupled612to a memory620. A servo program system1000may direct the servo computer in implementing the method operating the hard disk drive10. The servo program system preferably includes at least one program step residing in the memory. The embedded circuit may preferably be implemented with a printed circuit technology. The lateral control signal82may preferably be generated by a micro-actuator driver28. The lateral control signal preferably includes the first lateral control signal82P1and the second lateral control signal82P2, as well as the AC lateral control signal82AC. The lateral control signal may further include one or more second micro-actuator lateral control signals82A.

The voice coil driver30preferably stimulates the voice coil motor18through the voice coil32to provide coarse position of the slider90, in particular, the read head94-R near the track122on the disk surface120-1.

The embedded circuit500may further process the read signal25-R during the read access to the data122on the disk surface120-1. The slider90reports the amplified read signal ar0as the result of a read access of the data122on the disk surface120-1. The flexure finger20provides the read trace path rtp for the amplified read signal, as shown inFIG. 8C. The main flex circuit200receives the amplified read signal from the read trace path to create the read signal25-R. The embedded circuit receives the read signal to read the data on the disk surface.

Manufacturing the assembled hard disk drive9may include pivotably mounting the voice coil assembly50by an actuator pivot58to the disk base14and arranging the voice coil assembly, the disk12, and the spindle motor270for the slider90of the head gimbal assembly60to access the data122on the disk surface120-1of the disk12rotatably coupled to the spindle motor, to at least partly create the assembled hard disk drive9. The invention includes this manufacturing process and the hard disk drive as a product of that process.

Manufacturing the assembled hard disk drive9may further include electrically coupling the voice coil assembly50to the embedded circuit500to provide the read signal25-R as the result of the read access of the data122on the disk surface120-1. It may further include coupling the servo controller600and/or the embedded circuit500to the voice coil motor18and providing the micro-actuator stimulus signal650to drive the micro-actuator assembly80. And electrically coupling the vertical control driver of the embedded circuit to the vertical control signal VcAC of the slider90through the voice coil assembly50, in particular through the flexure finger20.

Manufacturing the hard disk drive10from the assembled hard disk drive9preferably includes loading the burn-in program system800into the servo memory620, as shown inFIGS. 1 and 15, and then executing the burn-in program system, which implements the method of initializing the raw disk12before to create the written-in parameter list320L for the RRO corrector function Wc320for the track122on the disk surface120-1. This process is preferably performed for every track to be used for data access, as shown inFIG. 5A. This process may further preferably be performed for each disk surface included the hard disk drive.

Making the servo controller600and/or the embedded circuit500may include programming the servo memory620with the servo program system1000to create the servo controller and/or the embedded circuit, preferably programming a non-volatile memory component of the servo memory. Making the embedded circuit, and in some embodiments, the servo controller, may include installing the servo computer610and the servo memory into the servo controller and programming the memory with the servo program system to create the servo controller and/or the embedded circuit.

Looking at some of the details ofFIG. 11, the hard disk drive10includes a disk12and a second disk12-2. The disk includes the disk surface120-1and a second disk surface120-2. The second disk includes a third disk surface120-3and a fourth disk surface120-4. The voice coil motor18includes an voice coil assembly50pivoting through an actuator pivot58mounted on the disk base14, in response to the voice coil32mounted on the head stack54interacting with the fixed magnet34mounted on the disk base. The actuator assembly includes the head stack with at least one actuator arm52coupling to a slider90containing the read-write head94. The slider is coupled to the micro-actuator assembly80.

The read-write head94interfaces through a preamplifier24on a main flex circuit200using a read-write signal bundle rw typically provided by the flexure finger20, to a channel interface26often located within the servo controller600. The channel interface often provides the Position Error Signal260(PES) within the servo controller. It may be preferred that the micro-actuator stimulus signal650be shared when the hard disk drive includes more than one micro-actuator assembly. It may be further preferred that the lateral control signal82be shared. Typically, each read-write head interfaces with the preamplifier using separate read and write signals, typically provided by a separate flexure finger. For example, the second read-write head94-2interfaces with the preamplifier via a second flexure finger20-2, the third read-write head94-3via the a third flexure finger20-3, and the fourth read-write head944via a fourth flexure finger20-4.

During normal disk access operations, the hard disk drive10operates as follows when accessing the data122on the disk surface120-1. The spindle motor270is directed by the embedded circuit500, often the servo-controller600, to rotate the disk12, rotating the disk surface for access by the read-write head94. The embedded circuit, in particular, the servo controller drives the voice coil driver30to create the voice coil control signal22, which stimulates the voice coil32with an alternating current electrical signal, inducing a time-varying electromagnetic field, which interacts with the fixed magnet34to move the voice coil parallel the disk base14through the actuator pivot58, which alters the lateral position LP of the read-write head of the slider90in the head gimbal assembly60coupled to the actuator arm52, which is rigidly coupled to the head stack54pivoting about the actuator pivot. Typically, the hard disk drive first enters track seek mode, to coarsely position the read-write head near the data, which as stated above, is typically organized as a track. Once the read-write head is close to the track, track following mode is entered. Often this entails additional positioning control provided by the micro-actuator assembly80stimulated by the lateral control signal82, which is driven by the micro-actuator driver28. In certain embodiments of the hard disk drive supporting triple stage actuation, the second micro-actuator80A may be further stimulated by one or more, second micro-actuator lateral control signals82A. Reading the track may also include generating a Position Error Signal260, which is used by the servo controller as positioning feedback during track following mode. The PES signal may be converted into an internal numeric format to create the PES pre-RRO310signal shown inFIGS. 2A,2B,3,4,6,15,16A,18A,18B, and19.

The hard disk drive10may operate by driving the vertical control signal VcAC to stimulate the vertical micro-actuator98to increase the vertical position VP of the slider90by providing a potential difference to the first slider terminal SP1. This operation may be performed when seeking a track122of data on the disk surface120-1, and/or when following the track on the disk surface. The servo controller600may include means for driving the vertical control signal, which may be at least partly implemented by the vertical control driver29creating the vertical control signal to be provided to the vertical micro-actuator. The vertical control driver is typically an analog circuit with a vertical position digital input290driven by the servo computer610to create the vertical control signal.

Track following and track seeking may be implemented as means for track seeking and means for track following, one or both of which may be implemented at least in part as program steps in the program system1000residing in the memory620accessibly coupled612to the servo computer610shown inFIG. 6. Alternatively, the means for track seeking and/or the means for track following may be implemented as at least one finite state machine.

The methods of this invention may be implemented as means for performing the operations of each method. By way of example, the method of using the written-in parameter list320L is shown implemented within the hard disk drive10inFIGS. 3,4,18A and18B in a manner to illustrate the means for implementing the steps of the method.

Means for acquiring1002said written-in RRO corrector parameter list320L for said track122from said disk surface122-1to recreate said voice coil motor control contribution B, said voice coil motor plant contribution A, and said micro-actuator control contribution F is shown inFIGS. 3,4,18A and18B. The means for acquiring further recreates the micro-actuator plant contribution G inFIGS. 3,18A and18B. The means for acquiring further recreates the second micro-actuator control contribution L inFIGS. 18A and 18B. The means for acquiring further recreates the second micro-actuator plant contribution M inFIG. 18A.

The means for controlling actuation is shown inFIGS. 3,4,18A and18B as the interaction of the servo controller600with the voice coil motor and micro-actuator plant3100, which includes the following. Means for calculating the RRO corrector filter Wc320F based upon said micro-actuator control contribution F applied to a micro-actuator control queue Uma304, said voice coil motor control contribution A applied to a voice coil motor control queue Uc302, and said voice coil motor plant contribution B applied to a voice coil motor plant queue Yp334, to create the RRO micro-actuator control corrector value WmaVal 320 ma, and the RRO voice coil assembly corrector value WvcaVal 320 vca. Means for calculating3010the RRO corrector value WcVal as said RRO micro-actuator control corrector value added to said RRO voice coil assembly corrector value. Means for calculating3012the Position Error Signal (PES) post-RRO312as the PES pre-RRO310minus the RRO corrector value. And means for performing3000the Non-Repeatable Run-Out (NRRO) control based upon the PES post RRO and updating said micro-actuator control queue, said voice coil motor control queue, and said voice coil motor plant queue.

Any and/or all of the means of the methods of this invention may at least one instance of at least one of a computer, an inferential engine, at least one finite state machine and/or a neural network. The discussion herein has focused on a computer implementation to aid in presenting the invention. This is not meant limit the scope of the Claims, but rather clarify the operations of the invention's method of initializing the raw disk12before in the assembled hard disk drive9as well as the invention's method of using the written-in parameter list320L for the Repeatable Run-Out corrector function Wc320in the hard disk drive10.

The preceding embodiments provide examples of the invention and are not meant to constrain the scope of the following claims.