JP2000011564A - Magnetic disk device and analyzing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the reliability and developing efficiency of a magnetic disk device. SOLUTION: In this magnetic disk device, positioning error response waveforms at the time when a head is set in a target position are observed by a plurality of times (step 102), and averaging is performed (step 103). A mode identification is performed for an averaged settling response waveform (step 104), and the waveform is separated into a mechanism system response and a control system response based on a mode damping ratio as a part of the obtained identifying result (step 107). If the amplitude of a particular mode obtained as a result of the mode identification is equal to or lower than a specified value, or if the amplitude quantity of the mechanism system response or the control system response is equal to or higher than a specified value, damage generation prevention processing such as the changing of a seeking operation determination condition or the like is performed (step 112).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive for analyzing the positioning characteristics of a magnetic head and an analyzer therefor, and more particularly to a magnetic disk drive for analyzing the positioning characteristics of a magnetic head due to a mechanical system and a circuit system. It relates to the analysis device.

[0002]

2. Description of the Related Art Generally, in a magnetic disk drive, a plurality of recording units concentrically arranged on a magnetic disk are called tracks, and a unit obtained by dividing the plurality of tracks in a circumferential direction is called a sector. The magnetic disk records position information indicating the position of the magnetic head in units of the sector, and this position information is called sector servo data, and includes a portion indicating a track number and a portion indicating a deviation amount from a track center. And the relative displacement between the magnetic disk and the magnetic head. In the present specification, the difference between the positioning target position (target track) of the magnetic head and the head position obtained from the position information is called a position error, and the movement of the head to the target position is called a seek operation. An operation of settling to the target position after reaching the vicinity of the target position (settling: an operation of converging the position while oscillating on the target track, for example) is particularly called a settling operation.

[0003] The magnetic disk device operates to move the magnetic head to a target position and stop at a target position (track) using the position information. This operation is roughly classified into three operations of a seek system, a settling system, and a following system. The seek system controls the moving speed of the magnetic head in accordance with the distance from the current position of the head to the target position, and approaches the target position. To move at high speed to
The settling system positions the magnetic head having vibrations on the target position due to a mechanism close to the target position and a control factor, and the following system keeps the magnetic head at the target position.

The end of the seek operation is generally determined based on the position error during the settling operation, and it is determined that the state where the position error is equal to or less than a predetermined value (error condition) continues for a predetermined time (time condition) for a predetermined time (time condition). It is often a condition. The end of the seek operation is determined by changing the error condition and the time condition according to whether the operation to be performed after the seek operation is the writing operation or the reproducing operation, or the moving distance of the seek operation. This is because the positioning accuracy (high accuracy) required for data reproduction is different from the positioning accuracy (high accuracy) required for the target position of the magnetic head when data recording is performed. If it is determined that the seek operation has been completed and the position error exceeds a certain value, the recording operation and the reproducing operation are generally prohibited as a positioning error.

On the other hand, the evaluation and analysis of the positioning error during the settling operation are generally performed using the amount of overshoot (overshoot with respect to the target) and the amount of vibration of the magnetic head as index values. In addition, the average and variance (standard deviation) of the position errors immediately after the end of the seek operation are often used as index values.

Incidentally, as a document describing a general technique relating to the positioning of a magnetic head, for example, Japanese Patent Laid-Open No. 9-26 is disclosed.
574.

[0007]

In a recent magnetic disk drive, an increase in data storage capacity and a further improvement in data access performance are required. Therefore, a magnetic head can be moved to a target position at a high speed and a high precision can be achieved. Need to be settled. The problem at this time is the vibration of the position error during the settling operation (hereinafter referred to as settling vibration).

The cause of the settling vibration is considered to be resonance of the head drive mechanism, vibration of the device housing, abnormality of the control system, and the like. The vibration caused by these causes changes according to the driving force pattern, that is, the seek span. In particular, since the vibration caused by the vibration of the device housing also depends on the fixed state of the magnetic disk device, it is often difficult to take countermeasures.

[0009] In order to prevent data recording / reproducing failure due to the settling vibration, it is necessary to detect the occurrence of the settling vibration and also to detect the cause of the settling vibration. Very important. For example, if it is caused by resonance of the head drive system, it is necessary to re-adjust the notch filter or eliminate the device as a rejected product, which is caused by vibration of the device housing. If so, it is necessary to change the device fixing method. Further, in both cases, measures such as changing the seek operation end determination condition and the control mode according to the respective degrees are also conceivable. If it is caused by a control system abnormality, readjustment of the control system such as gain adjustment is required. On the other hand, in order to improve the positioning accuracy, it is necessary to quantitatively analyze what mainly causes the current settling vibration. As described above, the magnetic disk device needs to analyze the settling vibration generated at the time of the positioning operation of the magnetic head, and take the above-described countermeasures based on the analysis result. There is a problem that it is difficult to sufficiently analyze the settling vibration.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, and to accurately analyze settling vibration, improve the reliability of a magnetic disk drive, and improve development efficiency. It is to provide a device and an analysis device.

[0011]

In order to achieve the above object, the present invention provides a magnetic disk having a position information recording area for recording position information and a data recording area for recording and reproducing data, and a position information of the magnetic disk. A magnetic head for detecting position information from a recording area, a demodulation unit for demodulating the detected position information, and a drive unit including a drive mechanism and a drive circuit for moving the magnetic head to an arbitrary position on the magnetic disk; A control unit for giving a command to a drive unit based on the demodulated position information to control the positioning of the magnetic head, wherein the control unit performs positioning when the magnetic head is settled at a target position. The error response waveform is measured, a plurality of modes of the measured positioning error response waveform are identified, and the amplitude of a specific mode among the identified modes is a predetermined value. To analyze the positioning characteristics of the magnetic head by comparing less than or above or the first feature.

The present invention further provides a magnetic disk having a position information recording area for recording position information and a data recording area for recording and reproducing data, a magnetic head for detecting position information from the position information recording area of the magnetic disk. A demodulation unit for demodulating the detected position information; a driving unit including a driving mechanism and a driving circuit for moving the magnetic head to an arbitrary position on the magnetic disk; and a driving unit based on the demodulated position information. And a control unit for controlling the positioning of the magnetic head by giving a command to the magnetic disk drive, wherein the control unit observes a positioning error response waveform when the magnetic head settles at a target position, and Mode identification, and the positioning error response waveform is converted into a mechanical system response and a control system response based on the mode damping ratio that is a part of the obtained identification result. Apart, the second, comprising a function of comparing the predetermined value with the vibration amount of the mechanical system response or the control system response.

The present invention also provides a magnetic disk having a position information recording area for recording position information and a data recording area for recording and reproducing data, a magnetic head for detecting position information from the position information recording area of the magnetic disk. A demodulation unit for demodulating the detected position information; a driving unit including a driving mechanism and a driving circuit for moving the magnetic head to an arbitrary position on the magnetic disk; and a driving unit based on the demodulated position information. In the analysis device to analyze a magnetic disk device having a control unit that gives a command to control the positioning of the magnetic head, the positioning error response waveform when the magnetic head settles to the target position is observed a plurality of times, A third feature is that it has a function of averaging the positioning error response waveform and performing mode identification on the averaged response waveform.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a magnetic disk drive and an analyzer according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a flowchart showing a procedure of a settling response analysis method according to an embodiment of the present invention. FIG. 2 is a block diagram showing an example of the structure of a positioning control system.
Is a pseudo waveform that simulates a position error response (settling response) at the time of settling to a target position (settling operation). FIGS. 4 to 7 show the results of moat identification of the waveform of FIG. 3 using a method called the Prony method. FIG. 4 is a diagram showing the frequency, vibration amplitude and damping rate of the vibration mode, FIG. 5 is a diagram showing the damping ratio and vibration amplitude of the over damping mode, and FIG. 6 is a diagram showing a time response waveform reproducing only the vibration mode. 7, FIG. 7 shows a time response waveform reproducing only the overdamped mode, FIG. 8 shows a waveform obtained by adding observation noise to the pseudo waveform shown in FIG. 3, and FIGS. 9 to 12 show the waveforms of FIG. FIG. 9 shows the results of identification.
FIG. 10 shows the frequency, vibration amplitude and damping rate of the vibration mode, FIG. 10 shows the damping rate and vibration amplitude of the over damping mode, FIG.
1 is a diagram showing a time response waveform reproducing only the vibration mode,
FIG. 12 is a diagram showing a time response waveform in which only the overdamping mode is reproduced.

First, the positioning control system circuit of the magnetic head of the magnetic disk drive according to the present embodiment and its operation are shown in FIG.
This will be described with reference to FIG.

When a magnetic disk drive receives a write or read command from a host, the magnetic head is driven in accordance with the distance from the current position (track) of the magnetic head positioned on the magnetic disk to the target position (track). Position control of the seek system (acceleration / constant speed / deceleration of the magnetic head according to the distance) by controlling the moving speed of the magnetic head, and then positioning the magnetic head on the target position when approaching the vicinity of the target position A position control of a following system for maintaining the magnetic head at a target position after the settling falls within a predetermined range, and
These controls are performed by the positioning control system shown in FIG.

This control system performs positioning control of the control target 212 (magnetic head) with respect to the target position 201 using the position target 201, the position disturbance 203, and the force disturbance 211 as input factors, and feeds back a displacement 213 described later. A switch 205 for switching the output using the position target 201 to which the position disturbance 203 has been added as an input.
A controller block 214 having a plurality of control modes (controllers 206 to 208) corresponding to the output of the switch 205, and a switch 209 for switching and outputting the output of the block 214 in accordance with the switch 205
And a control target 212 that inputs the manipulated variable 210 output from the switch 209 by adding a force disturbance 211 thereto, and a feedback path that returns the output of the control target 212 to the input target position 201. The controller block 214 includes the controller 20 that performs the above-described seek control.
6, a controller 207 for performing settling control,
And a controller 208 for performing a following system control. The position disturbance 203 is a disturbance component due to observation noise or the like, and the force disturbance is an amplifier noise or a disturbance component from the outside mechanically.

The positioning control system configured as described above outputs the difference between the target position 201 and the displacement 213 output from the control object 212 as a position error 202, and outputs this position error
A position error signal 204 obtained by adding the position disturbance 203 to 2 is input to the controller block 214 via the switch 205. At this time, the switch 205 switches the internal switch according to the selection of the control mode, and performs control so that the position error signal 204 is input to the corresponding controllers 206 to 208. For example, when the position error signal 204 is large, that is, when the distance to the target position is large, the controller 2
06, the head is moved at high speed to the target position by performing speed control, and when the position error signal 204 becomes small, that is, when the head reaches the vicinity of the target position, the controller is switched to the controller 207 to settle to the target position. (Settling) is performed, and after the head is settled at the target position, the operation is performed so as to switch to the controller 208 suitable for following the target position.

The output of the controller block 214 becomes an operation amount 210, and the operation amount 210 is input to a controlled object 212 by adding a force disturbance 211, and a displacement based on the control result (movement result of the magnetic head) is fed back to a target position. You.

As described above, the positioning control system for controlling the movement of the magnetic head, which is the object of the present embodiment, uses the position error signal 2
By switching operation modes of a seek system, a settling system, and a following system according to the size of the magnetic head 04, the magnetic head is positioned at a high speed and with high accuracy on the target track.

Next, based on the position error response (settling response) waveform at the time of settling to the target position (settling operation) according to the present embodiment, the response of the vibration of the mechanical system hidden in the response of the control system is clearly analyzed. FIG. 3 illustrates a method of quantifying and analyzing how much overshoot or vibration is caused by mechanical system vibration and control system response, respectively.
This is a simulated waveform simulating a position error response (settling response) when the magnetic head is set to a target position (settling operation) by the above-described positioning control system, and the position error was about 1.7 at time 0. Shows a waveform that abruptly attenuates, returns once, gradually attenuates to the target position, and is positioned.

FIGS. 4 to 7 show the results of moat identification of the waveform of FIG. 3 using a method called the Prony method. still,
Generally, moat identification is parameter identification for separating a transient response waveform into a plurality of damping responses represented by an exponential decay function. In the present embodiment, the pseudo waveform of the settling response is divided into a plurality of vibration modes and overdamping. In order to separate the modes, it is necessary to identify the parameters of each mode, such as frequency, vibration amplitude, damping rate, and initial phase. FIG. 4 shows the frequency, the vibration amplitude and the damping rate for the vibration mode, and FIG. 5 shows the damping rate and the vibration amplitude for the over damping mode. Here, the identification results in FIGS. 4 and 5 match the true values. The vibration mode shown in FIG. 4 simulates the vibration of the mechanical system and has a high vibration frequency component (attenuation rate: σ = 100).
0) simulates the resonance frequency of the drive mechanism system, and the low vibration frequency component (attenuation rate: σ = −500) simulates the housing vibration of the positioning device (for example, a magnetic disk device). It indicates that there is.

This high vibration frequency component (σ = 1000)
The frequency and damping ratio of the drive mechanism system resonance can be predicted by prior analysis and experiments, and it is possible to easily determine which of the identified modes corresponds to the drive mechanism system resonance. Similarly, regarding the resonance of the housing vibration system due to the low vibration frequency component (σ = −500), since the frequency and the damping ratio can be estimated to some extent in advance, it is possible to specify which of the identified modes is the housing vibration. it can. However, in general,
It should be noted that the drive mechanism resonance slightly varies in amplitude and frequency depending on the individual device variation and temperature conditions, and the housing vibration slightly varies depending on the fixed conditions of the device.

The overdamping mode shown in FIG. 5 simulates a control system response. In general, the response mode of the control system has a larger damping ratio than the vibration mode of the mechanical system. Therefore, even if the damping ratio is not overdamped, a mode in which the damping ratio is larger than a predetermined value can be separated as the control system response. In the over-attenuation mode shown in FIG. 5, the attenuation rates are about 500 rad / s and about 1500, respectively.
rad / s, 2000 rad / s, 2500 rad /
It turns out that it attenuates at s, 3000 rad / s.

FIGS. 6 and 7 show vibration modes (mechanical system vibration) obtained by separating the above-described results into a vibration mode (mechanical system vibration) and an overdamping mode (control system response), and then converting each of them into a time response again. FIG. 7 is a diagram illustrating an over-attenuation mode (control system response).

Referring to FIG. 6, the mode (mechanism system vibration) is a mode in which the position error initially overshoots and gradually attenuates while oscillating with the passage of time. (Control system response)
As is clear from FIG. 7, it can be seen that the mode is a mode that gradually decreases from time 0.

As described above, the mode of the position error response (settling response) waveform at the time of settling (settling operation) to the target position is identified and separated into a vibration mode (mechanical system vibration) and an overdamping mode (control system response). By separating each into the vibration mode (mechanical system vibration) and the overdamping mode (control system response), each of which has been converted into a time response again, the response of the mechanical system vibration hidden in the control system response has been clarified. I understand. Further, by separating the two responses, it is possible to quantify, for example, how much the overshoot or the vibration is caused by the mechanical system vibration and the control system response, respectively.

Next, one point of caution when applying the above analysis to an actual magnetic disk drive will be described. In the analysis method according to the present embodiment, the positioning control described with reference to FIG. 2 is applied to the pseudo waveform of the position error response (settling response) when the magnetic head is set to the target position (settling operation) shown in FIG. The observation noise (position disturbance 203) (in the actual device) added to the system is added to obtain a waveform of a position error response (settling response) at the time of (settling operation). As shown in FIG. 8, this waveform attenuates while swinging up and down as compared to the waveform shown in FIG.

In the analysis method according to the present embodiment, various modes are identified by the method described above based on the waveform of the position error response (settling response) shown in FIG. 8, and the frequency and the frequency related to the identified vibration mode shown in FIG. Waveform diagram of vibration amplitude and damping rate, damping rate for the identified overdamping mode shown in FIG.
A vibration amplitude waveform diagram, a reproduction time response waveform diagram for the vibration mode shown in FIG. 11, and a reproduction time response waveform diagram for the overdamping mode shown in FIG. 10 shown in FIG. 12 are obtained.

The damping rate of the actual device shown in FIG. 9 is higher than the resonance frequency (3000 Hz) of the driving mechanism system as compared with the pseudo model of FIG.
(Neighborhood) is reduced to about 1/3, and it is found that the frequency is dispersed in the lower frequency region than the frequency. The over-attenuation mode shown in FIG. 10 is dispersed in the lower frequency region as compared with the pseudo model in FIG. It can be seen that the reproduction time response for the vibration mode shown in FIG. 11 is attenuated while swinging up and down as compared to the pseudo model of FIG. 5, and that the identification result error also oscillates. The time response is shown in FIG.
It can be seen that, although the attenuation is substantially the same as that of the pseudo model, an identification result error occurs slightly at the beginning.

The magnetic disk drive according to the present embodiment has a function of executing the above-described analysis method in the magnetic disk drive itself, and the frequency, the vibration amplitude, the damping rate waveform, and the like relating to the identification vibration mode of the real device in the positioning control system. A waveform of the damping rate and vibration amplitude for the identified overdamping mode, a reproduction time response waveform for the vibration mode, and a reproduction time response waveform diagram for the overdamping mode are obtained. The analyzer of the magnetic disk drive according to the present embodiment also has a function of executing the above-described analysis method, drives the connected magnetic disk drive to perform positioning control, and similarly performs the identification vibration of the real device in the positioning control system. A waveform of the frequency, vibration amplitude, and damping rate for the mode, a damping rate and vibration amplitude for the identified overdamping mode, a reproduction time response waveform for the vibration mode, and a reproduction time response waveform chart for the overdamping mode are obtained.

From the magnetic disk device and the analyzing device that have performed this analysis, the position error signal includes a position disturbance (observation noise) as shown in FIG. 2 and a synchronous or asynchronous vibration that is not directly related to the settling response. Therefore, there is a risk that the mode identification is affected by these components and erroneous analysis results as shown in FIGS. 9 to 12 are obtained. In order to avoid this, the settling response waveform must be changed. It is necessary to perform waveform averaging by observing a plurality of times to remove components that are not directly related to the settling response.

FIG. 1 is a flowchart summarizing the above series of flows. Magnetic disk device 1 to be measured
01 is repeatedly observed (step 102), and an averaging process step is performed (step 10).
3). The mode of the obtained averaged settling response waveform is identified using the Prony method or the like (step 104). As the identification result, respective values of the vibration frequency, the vibration amplitude, the damping rate, the damping ratio, and the initial phase are obtained. By comparing the identification result and the prior information (105), it is determined whether or not the vibration amplitude of a mode determined as a specific mechanical system resonance or a housing vibration mode is larger than a predetermined value (step 106). Executes a failure occurrence process on the magnetic disk device or gives an instruction to the magnetic disk device (step 112). On the other hand, the mode identification result is based on the obtained system damping ratio
(Step 108) and the control system response (Step 110) (Step 107), and it is determined whether or not each vibration amount is larger than a predetermined value (Step 109, Step 1).
11). If the amount of vibration is larger than the predetermined value, a failure occurrence process is executed for the magnetic disk device or an instruction thereof is issued to the magnetic disk device (step 112). here,
Mechanical system vibration (Step 108) and control system response (Step 1)
As the vibration amount of 10), it is conceivable to use a 2-norm of a discrete signal or the like.

FIG. 13 is a diagram showing an example of an analyzer for performing the above settling response analysis. The analysis device 1308 according to the present embodiment is a magnetic disk device 1 to be analyzed.
The settling response waveform of 301, that is, the position error signal 1302 during the settling operation is collected by the data input unit 1303, the collected data is stored in the storage device 1305, and the completion of the data collection is notified to the arithmetic processing unit 1304. The processing unit 1304 identifies the mode of the settling response waveform stored in the storage device 1305, determines the mode identification result using the advance information also stored in the storage device 1305, and determines the mode identification result for the magnetic disk as necessary. To execute the failure occurrence processing or instruct the magnetic disk device to issue the instruction. The arithmetic processing unit 1304 issues a seek operation command for measuring the settling response waveform to the magnetic disk, and issues a measurement start command to the data input unit 1303. The identification result is displayed on the display unit 1306.

The magnetic disk drive and the analyzer according to the present embodiment measure various response waveforms based on the settling response waveform a plurality of times, and perform averaging processing of the waveforms.
Based on the analysis results, the setting of various parameters of the positioning control system of the magnetic disk drive (for example, other parameters such as the gain of the settling system controller 207 shown in FIG. 2) is adjusted, and the material of the magnetic head, the magnetic head drive system, and the housing 9 to 1 by changing the structure and the like.
The various response characteristics shown in FIG. 2 can be kept within a predetermined margin, and the positioning characteristics of the magnetic disk drive can be improved.

As described above, the magnetic disk drive and the analyzer according to the present embodiment provide a positioning error response waveform (settling response waveform) when the magnetic head is settled at the target position.
Is observed, mode identification is performed on the settling response waveform, and the positioning error response waveform is separated into a mechanical response and a control response based on the modal damping ratio that is a part of the obtained identification result. By comparing the amount of vibration of the control system response with a predetermined value, it is detected whether or not settling is abnormal. Further, based on the mode frequency and the mode attenuation ratio, which are part of the obtained identification result, head drive system resonance or housing vibration is detected, and it is determined whether or not the vibration amplitude is within an allowable range. The reliability of the magnetic disk device can be improved by performing processing such as changing the seek operation end determination condition according to the determination result. Further, by performing the mode identification, it becomes possible to separate the factors of the settling vibration and quantitatively evaluate it, thereby improving the development efficiency.

The present invention can be represented by the following embodiments. <First Embodiment> A disk provided with a position information recording area and a data recording area, a spindle motor for rotating the disk, position information recorded in the position information recording area, and a head for detecting the position information A demodulation unit for demodulating the detected position information, a driving unit including a driving mechanism and a driving circuit for moving the head to an arbitrary position on the disk, and a driving unit based on the demodulated position information. For a magnetic desk device having a positioning control operation unit that gives a command to the head, a positioning error response waveform when the head is settled at a target position is observed a plurality of times, and the positioning error response waveform is averaged. An analysis apparatus for a magnetic disk drive, having a function of performing mode identification on a normalized response waveform.

<Embodiment 2> A disk provided with a position information recording area and a data recording area, a spindle motor for rotating the disk, position information recorded in the position information recording area, and detection of the position information Based on the demodulated position information, a demodulation unit for demodulating the detected position information, a driving unit including a driving mechanism and a driving circuit for moving the head to an arbitrary position on the disk, Targeting a magnetic desk device having a positioning control operation unit for giving a command to the drive unit, observing a positioning error response waveform when the head settles to a target position, performing mode identification on the positioning error response waveform, and A function of separating the positioning error response waveform into a mechanical system response and a control system response based on a mode damping ratio which is a part of the obtained identification result. Analysis apparatus of the magnetic disk drive.

<Embodiment 3> A disk provided with a position information recording area and a data recording area, a spindle motor for rotating the disk, position information recorded in the position information recording area, and detection of the position information Based on the demodulated position information, a demodulation unit for demodulating the detected position information, a driving unit including a driving mechanism and a driving circuit for moving the head to an arbitrary position on the disk, Targeting a magnetic desk device having a positioning control operation unit for giving a command to the drive unit, observing a positioning error response waveform when the head settles to a target position, performing mode identification on the positioning error response waveform, and A magnetic disk drive having a function of setting or instructing a failure occurrence avoidance process in the magnetic disk drive according to the identification result obtained. Of the analysis apparatus.

<Embodiment 4> A disk provided with a position information recording area and a data recording area, a spindle motor for rotating the disk, position information recorded in the position information recording area, and detection of the position information Based on the demodulated position information, a demodulation unit for demodulating the detected position information, a driving unit including a driving mechanism and a driving circuit for moving the head to an arbitrary position on the disk, In a magnetic desk device having a positioning control operation unit that gives a command to the drive unit, a positioning error response waveform when the head is settled at a target position is observed, mode identification is performed on the positioning error response waveform, and as a result, A magnetic disk drive having a function of comparing whether the obtained amplitude of a specific mode is equal to or larger than a predetermined value.

<Embodiment 5> A disk provided with a position information recording area and a data recording area, a spindle motor for rotating the disk, position information recorded in the position information recording area, and detection of the position information Based on the demodulated position information, a demodulation unit for demodulating the detected position information, a driving unit including a driving mechanism and a driving circuit for moving the head to an arbitrary position on the disk, In a magnetic desk device having a positioning control operation unit for giving a command to the drive unit, a positioning error response waveform when the head settles to a target position is observed, and mode identification is performed on the positioning error response waveform. The positioning error response waveform is separated into a mechanical system response and a control system response based on a mode damping ratio which is a part of the identification result, and the mechanical system response or the control system response is separated. Magnetic disk apparatus characterized by having a function of comparing the predetermined value with the vibration amount of answers.

<Embodiment 6> A disk provided with a position information recording area and a data recording area, a spindle motor for rotating the disk, position information recorded in the position information recording area, and detection of the position information Based on the demodulated position information, a demodulation unit for demodulating the detected position information, a driving unit including a driving mechanism and a driving circuit for moving the head to an arbitrary position on the disk, In a magnetic desk device having a positioning control operation unit that gives a command to the drive unit, a positioning error response waveform when the head is settled at a target position is observed, mode identification is performed on the positioning error response waveform, and as a result, It has a function of performing a failure occurrence avoidance process such as changing the seek operation end determination condition based on the obtained amplitude of the specific mode. The magnetic disk device that.

<Embodiment 7> A disk provided with a position information recording area and a data recording area, a spindle motor for rotating the disk, position information recorded in the position information recording area, and detection of the position information Based on the demodulated position information, a demodulation unit for demodulating the detected position information, a driving unit including a driving mechanism and a driving circuit for moving the head to an arbitrary position on the disk, In a magnetic desk device having a positioning control operation unit for giving a command to the drive unit, a positioning error response waveform when the head settles to a target position is observed, and mode identification is performed on the positioning error response waveform. The positioning error response waveform is separated into a mechanical system response and a control system response based on a mode damping ratio which is a part of the identification result, and the mechanical system response or the control system response is separated. Based on the vibration amount of the answer, a magnetic disk apparatus characterized by having a function of a failure avoidance processing such as changing the seek operation end determination condition.

[0045]

According to the present invention, it is possible to detect from the head positioning settling response analysis of a magnetic disk drive whether or not the apparatus is in a state that will lead to the occurrence of a data recording / reproducing error. By performing the processing, the reliability of the device can be improved. Further, from the settling response analysis, problems in the settling response can be quantified, and the development efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a flowchart showing a procedure of a settling response analysis method according to the present invention.

FIG. 2 is a diagram showing an example of the structure of a positioning control system of a magnetic disk device to which the present invention is applied.

FIG. 3 is a diagram showing an example of a pseudo waveform simulating a settling response waveform.

FIG. 4 shows the frequency for the identified vibration mode for FIG. 3,
The figure which shows the example of a display of a vibration amplitude and a damping rate.

FIG. 5 is a diagram showing a display example of a damping rate and a vibration amplitude related to the identified overdamping mode with respect to FIG. 3;

FIG. 6 is a view showing an example of a reproduction time response waveform relating to the vibration mode of FIG. 4;

FIG. 7 is a diagram showing an example of a reproduction time response waveform relating to the over-attenuation mode of FIG. 5;

8 is a diagram illustrating an example of a case where observation noise is added to the pseudo waveform illustrated in FIG. 3;

FIG. 9 shows the frequency for the identified vibration mode for FIG. 8,
The figure which shows the example of a display of a vibration amplitude and a damping rate.

FIG. 10 is a diagram showing a display example of a damping rate and a vibration amplitude regarding the identified over-damping mode with respect to FIG. 8;

FIG. 11 is a view showing an example of a reproduction time response waveform relating to the vibration mode of FIG. 9;

FIG. 12 is a diagram showing an example of a reproduction time response waveform relating to the over-attenuation mode of FIG. 10;

FIG. 13 is a diagram showing an example of the configuration of an analyzer according to an embodiment of the present invention.

[Explanation of symbols]

101: magnetic disk drive, 102: settling response waveform observation, 103: averaging process, 104:
Mode identification, 105: prior information, 106: specific mode amplitude determination, 107: settling response separation, 1
08 ... mechanical system vibration, 109 ... vibration amount judgment, 11
0: control system response, 111: vibration amount determination, 112
... execution of obstacle avoidance processing, 113 ... settling response analysis procedure, 114 ... end processing, 201 ... target position, 202 ... position error, 203 position disturbance, 20
4 ... Position error signal, 205 ... Switch, 206
... Controller, 207 ... Controller, 20
8 ... controller, 209 ... switch, 210
Manipulated variable, 211: force disturbance, 212: controlled object,
213: displacement, 214: controller block, 1301: analysis target, 1302: position error signal, 1303: data input unit, 1304: arithmetic processing unit, 1305: storage device 1306: display unit, 1307: seek command / failure avoidance process, 13
08 Analysis device

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shozo Saegusa 2880 Kozu, Odawara-shi, Kanagawa F-term in Hitachi, Ltd. Storage System Works (Reference) 5D096 AA02 BB01 DD05 EE03 GG10 HH11 KK11 KK12 RR01 RR02 RR09 RR12

Claims (3)

[Claims] A magnetic disk having a position information recording area for recording position information and a data recording area for recording and reproducing data; a magnetic head for detecting position information from the position information recording area of the magnetic disk; A demodulation unit for demodulating the position information, a driving unit including a driving mechanism and a driving circuit for moving the magnetic head to an arbitrary position on the magnetic disk, and a command to the driving unit based on the demodulated position information. And a control unit for controlling the positioning of the magnetic head by providing the control unit, the control unit measures a positioning error response waveform when the magnetic head is settled at a target position, and the measured positioning error response waveform. Of the magnetic head by identifying whether the amplitude of a specific mode among the identified modes is equal to or larger than a predetermined value. Magnetic disk apparatus characterized by analyzing the determined characteristics. 2. A magnetic disk having a position information recording area for recording position information and a data recording area for recording and reproducing data, a magnetic head for detecting position information from the position information recording area of the magnetic disk, A demodulation unit for demodulating the position information, a driving unit including a driving mechanism and a driving circuit for moving the magnetic head to an arbitrary position on the magnetic disk, and a command to the driving unit based on the demodulated position information. And a control unit for controlling the positioning of the magnetic head by providing the control unit, wherein the control unit observes a positioning error response waveform when the magnetic head settles at a target position, and identifies a mode with respect to the positioning error response waveform. The positioning error response waveform is separated into a mechanical system response and a control system response based on the modal damping ratio which is a part of the obtained identification result. Magnetic disk apparatus characterized by having a system response or function of comparing with a predetermined value amount of vibration of the control system response. 3. A magnetic disk having a position information recording area for recording position information and a data recording area for recording and reproducing data, a magnetic head for detecting position information from the position information recording area of the magnetic disk, A demodulation unit for demodulating the position information, a driving unit including a driving mechanism and a driving circuit for moving the magnetic head to an arbitrary position on the magnetic disk, and a command to the driving unit based on the demodulated position information. And a control unit for controlling the positioning of the magnetic head to provide a magnetic disk device for analysis, the positioning error response waveform when the magnetic head settles to the target position is observed a plurality of times, An analysis apparatus for a magnetic disk drive, having a function of averaging a positioning error response waveform and performing mode identification on the averaged response waveform.