JP3387451B2 - Positioning control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on one end of a fine movement actuator by cooperatively controlling a coarse movement actuator and a fine movement actuator fixed to one end of a coarse movement portion driven by the coarse movement actuator. More particularly, the present invention relates to a positioning control device that performs positioning control of a head of an optical disk device, a magnetic disk device, etc.

[0002]

2. Description of the Related Art Some disk devices such as an optical disk device and a magnetic disk device have recently been disclosed in Japanese Patent Laid-Open Publication No. 6-96545 in order to cope with the recent increase in recording density accompanying the increase in storage capacity. As disclosed in JP-A-9-251739 and Japanese Patent Laid-Open No. 9-251739, there is one in which a head is positioned at a predetermined position on an optical disk or a magnetic disk by a two-stage coordinated positioning mechanism or a head moving mechanism called a two-stage actuator. . This type of head moving mechanism is fixed to a coarse actuator with a large movable range of centimeter order but low positioning accuracy, and one end of an arm driven by this coarse actuator, and the movable range is millimeter order or nanometer. It consists of a fine motion actuator with a high accuracy in positioning, which is small in the order of meters. By cooperating with these, a large movable range of the order of centimeters and high positioning accuracy of the order of nanometers are both achieved.

Of these, in the optical disk device, since the voice coil motor is used for both the coarse movement actuator and the fine movement actuator, the movable range of the voice coil motor constituting the fine movement actuator is several mm. A positioning accuracy of about 30 nm is realized. On the other hand, in the magnetic disk device, a voice coil motor is used for the coarse movement actuator, but an electrostrictive element such as a piezo element is used for the fine movement actuator. The movable range of the strain element is very narrow, around 500 nm,
A positioning accuracy of nm or less is realized.

[0004]

By the way, in the above-mentioned head positioning control of the disk device, normally,
Feedback control is performed so as to eliminate the error between the target position and the actual position of the head, and an integrator is inserted in the feedback loop to suppress the influence from the outside. The control system with this integrator inserted is
Response tends to be slow. Therefore, when the vibration or impact applied from the outside exceeds the movable range of the fine motion actuator while the head is following the target position, the integrator with slow response causes so-called windup and the control system oscillates. , The head may run out of control. It is well known that the inconvenience that the control system oscillates generally occurs not only in the positioning control of the head of the disk device but also in the positioning control of the mechanism in which the movable range of the fine movement actuator is practically limited. .

In this regard, Japanese Unexamined Patent Publication No. 8-142886 discloses an anti-windup control for correcting the steering wheel positioning control in an electric power steering apparatus by correcting the internal state of an integrator that constitutes a control system. ing. However, this technique relates to general positioning control of one stage, and the positioning of the head is performed by coordinating two actuators like the positioning control of the head of a disk device such as an optical disk device or a magnetic disk device. Not applicable when controlling.

On the other hand, "Improvement of disturbance suppression characteristic of magnetic disk drive by anti-windup control" (Mechanical Society of Japan IIP, '98 Information, Intelligence, Precision Equipment Section Lecture Collection, No. 98-26, pp. 27-29), the internal state itself of the integrator constituting the control system was observed, and the output signal of the integrator was adjusted by using a limiter, whereby the head of the magnetic disk device moved to the vicinity of the target position. Techniques for speeding up the subsequent transient response settling are disclosed. However, in this technique, when the head is made to follow the target position, the vibration or shock applied from outside exceeds the movable range of the fine motion actuator,
Not applicable if the integrator winds up.

The present invention has been made in view of the above-mentioned circumstances, and finely adjusts the coarse movement actuator and the fine movement actuator fixed to one end of the coarse movement portion driven by the coarse movement actuator in cooperation with each other. When positioning the fine movement part attached to one end of the actuator, even if the external vibration or shock exceeds the movable range of the fine movement actuator, the effect of the vibration or shock can be reduced to perform highly accurate positioning control. It is an object of the present invention to provide a positioning control device that can be used.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 includes a coarse movement actuator and a fine movement actuator fixed to one end of a coarse movement portion driven by the coarse movement actuator. In a positioning control device for positioning a fine movement part attached to one end of a fine movement actuator by cooperatively controlling the fine movement part, a fine movement control for positioning the fine movement part based on a position error signal supplied from the fine movement part. A fine movement control means for generating a signal, a coarse movement control means for generating a coarse movement control signal to be supplied to the coarse movement actuator on the basis of the fine movement control signal, and a fine movement control signal for the movable range of the fine movement actuator. Saturation processing means for supplying saturation processing to the fine movement actuator so that it is within the limit corresponding to Of the output signal and the fine movement control signal, and a multiplier for multiplying the subtraction result of the subtractor by a predetermined constant to generate a correction signal for correcting the fine movement control signal. And means.

The invention according to claim 2 relates to the positioning control device according to claim 1, wherein the fine movement control means has an integral compensation means for integral compensation of the fine movement control signal, and based on the correction signal. Then, the internal state of the pre-stage integral compensation means is changed.

The invention according to claim 3 relates to the positioning control device according to claim 2, wherein the fine movement control means has a phase compensation means for phase compensating the fine movement control signal, and based on the correction signal. Then, the internal state of the front-stage phase compensating means is changed.

Further, the invention according to claim 4 relates to the positioning control device according to claim 2 or 3, wherein the sign of the correction signal is such that when the fine movement control signal is larger than the output signal of the saturation processing means. , Is set so that feedback is applied in a direction in which the internal state of the integral compensation means decreases,
When the fine movement control signal is smaller than the output signal of the saturation processing means, feedback is set so that the internal state of the integration compensation means increases.

The invention according to claim 5 relates to the positioning control device according to any one of claims 1 to 4, wherein the coarse actuator comprises a voice coil motor and the fine actuator comprises an electrostrictive element. The coarse moving part is composed of a carriage arm, and the fine moving part is composed of a magnetic head.

[0013]

[0014]

[0015]

According to the structure of the present invention, even if an externally applied vibration or shock exceeds the movable range of the fine movement actuator, the effect of the vibration or shock can be reduced and highly accurate positioning control can be performed.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The description will be specifically made using the embodiments. FIG. 1 is a block diagram showing an electrical configuration of a positioning control device 2 of a head moving mechanism 1 of a magnetic disk device according to an embodiment of the present invention. As shown in FIG. 2, the head moving mechanism 1 includes a coarse movement unit 11 including a carriage arm, a coarse movement actuator 12 including a voice coil motor, a fine movement actuator 13 including an electrostrictive element such as a piezo element, and a suspension. And a fine moving part 14 including a magnetic head. The coarse movement unit 11 has a coarse movement actuator 12 at one end thereof.
Is fixed, and a fine movement part 14 is attached to the other end via a fine movement actuator 13. The coarse movement actuator 12 drives the coarse movement portion 11 based on the control signal S _C1 supplied from the positioning control device 2 to move the fine movement actuator 13 and the fine movement portion 14 around the pivot 11a in the X direction (in the figure). The magnetic disk is moved in the radial direction (not shown). Further, the fine movement actuator 13 expands and contracts in the Y direction in the drawing based on the control signal S _C2 supplied from the positioning control device 2, and the fine movement unit 14
Is slightly moved in the X direction in the figure. The fine movement unit 14 outputs a position error signal S _E indicating the error between the position of the magnetic head to be positioned and the position of the target track, and supplies it to the positioning control device 2.

The head moving mechanism 1 is shown in FIGS. 3 and 4.
An example of the frequency characteristic of is shown. FIG. 3 shows an example of the frequency characteristic from the input end of the coarse movement actuator 12 to the output end of the fine movement portion 14 (corresponding to the position of the magnetic head when the track runout is set to zero). As an example, (b) is an example of a phase characteristic. As can be seen from FIGS. 3A and 3B, the gain characteristic in the low frequency range is −
It has a slope of 40 dB / dec and a phase characteristic of approximately -180.
Since it is in degrees, the control signal S _C1 corresponds to the dimension of the acceleration of the position of the magnetic head. Therefore, the control signal S
Even if there is a limit on the amplitude of _C1 , it is a limit on the acceleration and only the movable range of the coarse motion actuator 12 is reached until it physically hits a stopper or the like. Is not restricted. FIG. 4 shows an example of frequency characteristics from the input end of the fine movement actuator 13 to the output end of the fine movement unit 14 (corresponding to the position of the magnetic head when the track runout is zero), and FIG. 4A shows an example of the gain characteristic. , (B) are examples of phase characteristics. As can be seen from FIGS. 4A and 4B,
Since the gain characteristic in the low frequency range is substantially horizontal and the phase characteristic is substantially 0 degree, it can be seen that the control signal S _C2 directly corresponds to the dimension of the position of the magnetic head. Therefore, when the amplitude of the control signal S _C2 is limited by the power supply voltage or the like, it is directly as it is.
It will limit the movable range of. As described above, in the case of a typical magnetic disk device, the power supply voltage (for example, ±
The limit of the amplitude of the control signal S _C2 due to (for example, 30 V) is
Limitation of the movable range of the fine movement actuator 13 (for example, ±
500 nm), which is very narrow.

As shown in FIG. 1, the positioning control device 2 includes a sampler 21, an A / D converter 22, a sign inverter 23, a fine movement controller 24, a coarse movement controller 25, and a limiter 26. , Subtractor 27 and multiplier 28
, D / A converters 29 and 30, and filters 31 and 3
2 and 2. Of these, the sign inverter 23, the fine movement controller 24, and the coarse movement controller 2
5, the limiter 26, the subtractor 27, and the multiplier 28 are all composed of digital circuits. Sampler 21
The position error signal S _E supplied from the fine movement unit 14 of the head moving mechanism 1 is sampled at a predetermined cycle and the A / D converter 2
Supply to 2. The A / D converter 22 digitally converts the output signal of the sampler 21 into discrete position error data D _E and supplies it to the sign inverter 23. The sign inverter 23 inverts the sign of the position error data D _E to perform the fine movement controller 24.
Supply to.

The fine movement controller 24 generates output data D _C1 for positioning the magnetic head on the target track of the magnetic disk based on the position error data (-D _E ) and is shown in FIG. Integral compensator 4
1, a phase compensator 42, and an adder 43. The integral compensator 41 is roughly composed of an adder 44, a unit delay 45, and a multiplier 46. The adder 44 adds the output data DA of the multiplier 28, the position error data (−D _E ) and the output data of the unit delay 45, and supplies the addition result to the unit delay 45. The unit delay 45 is the adder 4
After delaying the output data of No. 4 by a predetermined time (1 / z), it is supplied to the adder 44 and the multiplier 46. The multiplier 46 outputs a predetermined constant (KiF) to the output data of the unit delay 45.
And the multiplication result is supplied to the adder 43.

The phase compensator 42 includes multipliers 47 to 50,
It is configured by adders 51 and 52 and a unit delay 53. Multipliers 47 and 48 convert the position error data (-D _E ) into predetermined constants (BF) and (D), respectively.
F) is multiplied and the multiplication result is supplied to the adders 51 and 52. The adder 51 adds the output data of the multiplier 47 and the output data of the multiplier 49 and supplies the addition result to the unit delay 53. The unit delay 53 delays the output data of the adder 51 by a predetermined time (1 / z) and then supplies the output data to the multipliers 49 and 50. Multipliers 49 and 5
0 multiplies the output data of the unit delay 53 by predetermined constants (AF) and (CF), respectively, and supplies the multiplication results to the adders 51 and 52. The predetermined constant (AF) of the multiplier 49 is the feedback gain that determines the pole of the phase compensator 42. The adder 52 adds the output data of the multiplier 48 and the output data of the multiplier 50 and supplies the addition result to the adder 43. The adder 43 adds the output data of the integral compensator 41 and the output data of the phase compensator 42, and supplies the addition result to the coarse movement controller 25, the limiter 26, and the subtracter 27 as output data D _C1 .
6A and 6B show examples of frequency characteristics of the fine movement controller 24. FIG. 6A shows an example of gain characteristics, and FIG. 6B shows an example of phase characteristics. As can be seen from FIG. 6, the fine movement controller 2
4 has an integral compensation as a basic role.

The coarse movement controller 25 is a fine movement controller.
Output data D of LA24_C1Of the fine actuator 13
The coarse motion actuator is set so that the displacement is regarded as zero.
Output data D for driving the data 12_C2Also produces
Therefore, as shown in FIG. 7, the integration compensator 61 and the phase
It is roughly composed of a compensator 62 and an adder 63.
The integral compensator 61 includes an adder 64 and a unit delay.
65 and a multiplier 66. Adder
64 is output data D of the fine movement controller 24 _C1When,
Add the output data of the unit delay 65
The result is supplied to the unit delay 65. unit·
The delay 65 outputs the output data of the adder 64 for a predetermined time.
After being delayed by (1 / z), it is supplied to the adder 64 and the multiplier 66.
To pay. The multiplier 66 outputs the output of the unit delay 65.
Multiply the data by a predetermined constant (KiC) and add the multiplication result
Supply to the container 63.

The phase compensator 62 includes multipliers 67 to 70,
It is configured by adders 71 and 72 and a unit delay 73. The multipliers 67 and 68 multiply the output data D _C1 of the fine movement controller 24 by predetermined constants (BC) and (DC), respectively, and add the multiplication result to the adder 71.
And 72. The adder 71 adds the output data of the multiplier 67 and the output data of the multiplier 69 and supplies the addition result to the unit delay 73. The unit delay 73 outputs the output data of the adder 71 for a predetermined time (1
/ Z) delay and then supply to multipliers 69 and 70. The multipliers 69 and 70 respectively include a unit delay 73.
The output data of is multiplied by a predetermined constant (AC) and (CC), and the multiplication result is supplied to the adders 71 and 72. Adder 7
2 adds the output data of the multiplier 68 and the output data of the multiplier 70 and supplies the addition result to the adder 63. The adder 63 adds the output data of the integral compensator 61 and the output data of the phase compensator 62, and supplies the addition result to the D / A converter 29 as output data D _C2 . FIG. 8 shows an example of the frequency characteristic of the coarse movement controller 25.
Is an example of a gain characteristic, and (b) is an example of a phase characteristic.
As can be seen from FIG. 8, the coarse movement controller 25 has a basic role of phase compensation for recovering the phase by about 60 degrees in the vicinity of the frequency of 500 Hz.

The limiter 26 shown in FIG. 1 processes the output data D _C1 of the fine movement controller 24 so as to be within the limit corresponding to the movable range of the piezo element forming the fine movement actuator 13, and outputs the processing result as output data. The DL is supplied to the D / A converter 30 and the subtractor 27. The subtractor 27 subtracts the output data D _C1 of the fine movement controller 24 from the output data DL of the limiter 26 and supplies the subtraction result to the multiplier 28. Further, the multiplier 28 is a subtractor 27
Is multiplied by a predetermined constant (AWG), and the multiplication result is used as output data DA, which is fed back to the fine movement controller 24 in order to modify the internal state (x _F2 ) of the integral compensator 41 constituting the fine movement controller 24. . When the output data D _C1 of the fine movement controller 24 is larger than the output data DL of the limiter 26, the sign of the fed back output data DA indicates that the internal state (x _F2 ) of the integral compensator 41 constituting the fine movement controller 24 is the same. The feedback is set to decrease, and when the output data D _C1 is smaller than the output data DL, the feedback is set to increase the internal state (x _F2 ) of the integral compensator 41. Be present.

Further, the D / A converter 29 converts the output data D _C2 of the coarse movement controller 25 into a continuous signal and supplies it to the filter 31. D / A converter 30
Outputs analog data from the output data DL of the limiter 26 to a continuous signal and supplies the continuous signal to the filter 32. Filter 31
Is the frequency band of the output signal of the D / A converter 29 is 500
After damping the mechanical resonance by limiting to about Hz, the coarse movement actuator 1 of the head moving mechanism 1 is used as a control signal S _C1.
Supply to 2. The filter 32 limits the frequency band of the output signal of the D / A converter 30 to around 2 kHz to attenuate the mechanical resonance, and then supplies it as the control signal S _{C2 to} the fine movement actuator 13 of the head moving mechanism 1.

Next, the operation of the positioning control device 2 having the above configuration will be described. First, the operation in a steady state in which the displacement caused by externally applied vibration or shock is within the movable range of the fine movement actuator 13 will be described.
The position error signal S _E supplied from the fine movement unit 14 constituting the head moving mechanism 1 to the positioning control device 2 is the sampler 2
After being sampled at 1, the position error data D _E is converted by the A / D converter 22, and the sign is inverted by the sign inverter 23 so that the position error data (−
It is supplied to the fine movement controller 24 as D _E ). As a result, in the fine movement controller 24, the output data D _C1 for positioning the magnetic head on the target track of the magnetic disk based on the position error data (−D _E ).
Is generated, and the output data D _C1 is generated by the coarse motion controller 2
5, supplied to the limiter 26 and the subtractor 27. The output data D _C1 of the fine movement controller 24 is processed by the limiter 26 so as to be within the limit corresponding to the movable range of the piezo element forming the fine movement actuator 13, and then is output as the output data DL by the D / A converter 30 and It is supplied to the subtractor 27. The output data DL of the limiter 26 is
After being analog-converted in the D / A converter 30, the frequency band thereof is limited to around 2 kHz in the filter 32 and is supplied to the fine movement actuator 13 of the head moving mechanism 1 as the control signal S _C2 . As a result, the magnetic head with suspension that constitutes the fine movement unit 14
Positioning is controlled with high accuracy in the band of around 2 kHz. In this case, since the displacement caused by externally applied vibration or shock is within the movable range of the fine movement actuator 13, the output data _DC1 of the fine movement controller 24 and the output data DL of the limiter 26 are equal. Therefore, the subtraction result of the subtractor 27 is zero, the output data DA of the multiplier 28 is not fed back to the fine movement controller 24, and the internal state (x _F2 ) of the integral compensator 41 constituting the fine movement controller 24 is adjusted. Not done.

On the other hand, the coarse movement controller 25
Output data D of the motion controller 24 _C1Based on
The coarse motion actuator is set so that the displacement of the dynamic actuator 13 becomes zero.
Output data D for driving the tuner 12_C2Raw
Is made. Output data D of coarse movement controller 25
_C2Is analog-converted in the D / A converter 29.
Then, in the filter 31, the frequency band is 500
Control signal S limited to about Hz_C1Move head as
It is supplied to the coarse movement actuator 12 of the mechanism 1. to this
As a result, the carriage arm that forms the coarse movement unit 11 moves slightly.
The magnetic head with suspension that composes part 14 is added.
Controlled to go.

As described above, in a steady state in which the vibration or impact applied from the outside is within the movable range of the piezo element which constitutes the fine movement actuator 13, the magnetic head with suspension is precisely moved to the target track of the magnetic disk. Coordinated control is achieved in which the carriage arm moves by the voice coil motor following the piezo element that has moved for positioning. Therefore, the rough movement is covered by the voice coil motor even when a large track shake cannot be positioned in the original movable range of the piezo element (corresponding to the case where the carriage arm is fixed). The highly accurate positioning state of the element can be maintained. In addition, the coarse movement controller 25
Can perform predictive control based on the output data D _C1 of the fine movement controller 24, and therefore, the stability of the control system is much higher than that in the case of using the output data DL after saturation processing in the limiter 26. Is improved.

Next, a large displacement which cannot be handled by the response speed of the voice coil motor constituting the coarse actuator 12 occurs due to externally applied vibration or shock, and the displacement of the piezoelectric element constituting the fine actuator 13 occurs. The operation when the movable range is exceeded will be described. Position error signal S _E supplied from the head moving mechanism 1
Is a sampler 21, an A / D converter 22, and a sign inverter 2
3 is sequentially processed, and the processing result is supplied to the fine movement controller 24 as position error data (-D _E ). As a result, the fine movement controller 24 generates the output data D _{C 1} based on the position error data (−D _E ), so that the output data D _C1 is within the limit corresponding to the movable range of the piezo element in the limiter 26. After being processed as described above, the D / A converter 3 outputs the output data DL.
0 and the subtracter 27. The output data DL is D
After being analog-converted in the / A converter 30, the frequency band thereof is limited to around 2 kHz in the filter 32 and is supplied to the fine movement actuator 13 of the head moving mechanism 1 as a control signal S _C2 . As a result, the magnetic head with suspension that constitutes the fine movement unit 14 is
Positioning is controlled with high accuracy in the band around kHz.

In this case, since the displacement caused by the externally applied vibration or shock is outside the movable range of the fine movement actuator 13, the absolute value of the output data D _{C 1} of the fine movement controller 24 is the output of the limiter 26. It is larger than the absolute value of the data DL. Therefore, in the subtractor 27, the fine movement controller 24 calculates from the output data DL of the limiter 26.
Output data D _C1 is subtracted, and the subtraction result is multiplied by a predetermined constant (AWG) in the multiplier 28,
The multiplication result is fed back to the fine movement controller 24 as the output data DA in order to correct the internal state (x _F2 ) of the integral compensator 41 forming the fine movement controller 24. As described above, when the output data D _C1 of the fine movement controller 24 is larger than the output data DL of the limiter 26, feedback is performed in the direction in which the internal state (x _F2 ) of the integral compensator 41 forming the fine movement controller 24 decreases. Since the sign of the output data DA is set in this way, the feedback reduces the internal state (x _F2 ) of the integral compensator 41 and reduces the output data D _C1 of the fine movement controller 24. The series of operations described above is repeated until the subtraction result of the subtractor 27 becomes zero. This suppresses the wind-up of the integral compensator 41 that occurs when the displacement caused by externally applied vibration or shock is outside the movable range of the piezo element that constitutes the fine movement actuator 13 of the head moving mechanism 1. It Therefore, the fine movement unit 1 of the head moving mechanism 1
It is possible to prevent runaway of the magnetic head that constitutes No. 4.

On the other hand, in the coarse movement controller 25,
Output data D of the motion controller 24 _C1Based on
The coarse motion actuator is set so that the displacement of the dynamic actuator 13 becomes zero.
Output data D for driving the tuner 12_C2Raw
Is made. Output data D of coarse movement controller 25
_C2Is analog-converted in the D / A converter 29.
Then, in the filter 31, the frequency band is 500
Control signal S limited to about Hz_C1Move head as
It is supplied to the coarse movement actuator 12 of the mechanism 1. to this
As a result, the carriage arm that forms the coarse movement unit 11 moves slightly.
The magnetic head with suspension that composes part 14 is added.
Controlled to go.

Here, FIG. 9 shows an example of an experimental result in the positioning control device 2 of the head moving mechanism 1 of the magnetic disk device having the above structure. FIG. 9A shows the head moving mechanism 1.
9B shows an example of the characteristic of the position error signal S _E output from the fine movement actuator 13, and FIG. 9B shows an example of the characteristic of the control signal S _C2 supplied to the fine movement actuator 13 of the head moving mechanism 1. In this experiment, a shock is artificially applied several times between the time 0 and about 0.01 seconds after that by hitting the housing of the magnetic disk device. Figure 9
As can be seen from (b), since the limit of the control signal S _C2 is ± 30 V in voltage conversion, the coarse actuator 12
The voice coil motor that composes the above can not absorb a large displacement of the piezo element that constitutes the fine movement actuator 13 due to the impact. Therefore, all the large position error of the magnetic head generated by the impact is absorbed by driving the piezo element, and the fine movement controller 24 outputs the large output data D _C1 (control signal S _C2 The voltage equivalent to ± 30 V or more) is output. As a result, the output data D _C1 is limited to ± 30 V by the limiter 26, and as can be seen from FIG. 9B, the control signal S _C2 is
Immediately after the shock is applied, it is saturated to ± 30V. Further, in this case, since the displacement caused by the impact applied from the outside is outside the movable range of the fine movement actuator 13, the positioning control device 2 cannot naturally maintain the original positioning accuracy, and the discrete position is not maintained. As can be seen from FIG. 9A, the error data D _E has an error of 3 μm or more. However, immediately after the impact is applied, the wind-up of the integral compensator 41 forming the fine movement controller 24 is suppressed based on the output data DA of the multiplier 28, so that 0.02 seconds have elapsed since the impact was applied. From this, it can be seen that the original positioning accuracy has returned to 100 nm or less.

On the other hand, FIG. 10 shows an example of a result obtained when an experiment similar to the above is performed without feeding back the output data DA of the multiplier 28 to the fine movement controller 24 in the positioning control device 2 having the above-mentioned configuration. There is. Figure 10
10A shows an example of the characteristic of the position error signal S _E output from the fine movement actuator 13 of the head moving mechanism 1, FIG.
(B) is an example of the characteristic of the control signal S _C2 supplied to the fine movement actuator 13 of the head moving mechanism 1. If the output data DA of the multiplier 28 is not fed back to the fine movement controller 24, a wind-up occurs in the integral compensator 41 immediately after the impact is applied, so that while the piezoelectric element is within the movable range, Integral compensator 4
1 cannot discharge the integrated internal state (x _F2 ) completely, and as can be seen from FIG. 10 (b), since the control signal S _C2 fluctuates drastically within ± 30 V, the control system oscillates,
The magnetic head goes out of control.

As described above, according to the configuration of this example, in order to suppress the wind-up of the integral compensator 41 constituting the fine movement controller 24, which causes the runaway of the magnetic head, the subtractor 27 and the multiplier 28 are used. Since such anti-windup means is provided, it is possible to provide a positioning control device that is resistant to external impacts even when the fine-movement actuator 13 that drives the fine-movement portion 14 has a narrow movable range. Further, according to the configuration of this example, the limiter 2
Since the output data D _C1 before being saturated by 6 is used for predictive control of the coarse movement actuator 12 by the coarse movement controller 25, the design range of the multiplier 28 for performing the anti-windup control is widened. It is possible,
Large stability margin.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and changes in design within the scope not departing from the gist of the present invention. Even this is included in this invention. For example, in the above-described embodiment, the example in which the output data DA of the multiplier 28 is supplied only to the integral compensator 41 constituting the fine movement controller 24 is shown, but the present invention is not limited to this, and the phase compensator of the fine movement controller 24 is shown. When the predetermined constant (AF) of the multiplier 49 constituting 42 is close to 1, the output data DA of the multiplier 28 is used to modify the internal state (x _F1 ) of the phase compensator 42. It may be configured to supply to.

Furthermore, in the above embodiment, the sign inverter 23, the fine movement controller 24, and the coarse movement controller 2 are used.
5, the limiter 26, the subtractor 27, and the multiplier 28 are shown as examples of digital circuits. However, the present invention is not limited to this, and any of these may be analog circuits. In this case, the A / D converter 22, the D / A converters 29 and 30
Is unnecessary. Further, in the above-described embodiment, the example in which the present invention is applied to the positioning control device of the head moving mechanism of the magnetic disk device has been shown, but the present invention is not limited to this. According to the present invention, the coarse movement actuator and the fine movement actuator fixed to one end of the coarse movement portion driven by the coarse movement actuator are cooperatively controlled to position the fine movement portion attached to one end of the fine movement actuator. Any positioning control device can be applied.

[0036]

As described above, according to the structure of the present invention, the fine movement control means for generating the fine movement control signal for positioning the fine movement portion based on the position error signal supplied from the fine movement portion, Coarse motion control means for generating a coarse motion control signal to be supplied to the coarse motion actuator based on the fine motion control signal, and saturation processing of the fine motion control signal within a limit corresponding to the movable range of the fine motion actuator. Saturation processing means for supplying to the fine movement actuator, a subtractor for obtaining the difference between the output signal of the saturation processing means and the fine movement control signal,
Since the subtraction result of the subtractor is multiplied by a predetermined constant to generate a correction signal for correcting the fine movement control signal, the correction means is provided. Even if the movable range is exceeded, it is possible to reduce the influence of vibration and impact and perform highly accurate positioning control. Further, it becomes possible to perform predictive control of the coarse motion actuator, widen the design range of the multiplier constituting the correction means, and have a large stability margin.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a positioning control device for a head moving mechanism of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a plan view showing a mechanical configuration of a head moving mechanism.

FIG. 3 is an example of frequency characteristics from an input end of a coarse movement actuator to an output end of a fine movement unit, (a) is an example of gain characteristics, and (b) is an example of phase characteristics.

FIG. 4 is an example of frequency characteristics from an input end of a fine movement actuator to an output end of a fine movement unit, (a) is an example of gain characteristics, and (b) is an example of phase characteristics.

FIG. 5 is a block diagram showing an electrical configuration of a fine movement controller.

FIG. 6 is an example of frequency characteristics of a fine movement controller,
(A) is an example of a gain characteristic, (b) is an example of a phase characteristic.

FIG. 7 is a block diagram showing an electrical configuration of a coarse movement controller.

FIG. 8 is an example of frequency characteristics of a coarse movement controller,
(A) is an example of a gain characteristic, (b) is an example of a phase characteristic.

FIG. 9 is an example of an experimental result in the apparatus, (a)
Is the position error signal S _E output from the fine actuator
2B is an example of the characteristic of the control signal S _C2 supplied to the fine movement actuator.

FIG. 10 is an example of a result when an experiment is performed in the same device without feeding back the output data DA to a fine movement controller, and (a) is an example of a characteristic of the position error signal S _E output from the fine movement actuator, b) is an example of the characteristic of the control signal S _C2 supplied to the fine movement actuator.

[Explanation of symbols]

1 Head moving mechanism 2 Positioning control device 11 coarse movement part 12 Coarse actuator 13 Fine actuator 14 Fine movement part 24 Fine movement controller (fine movement control means) 25 Coarse motion controller (coarse motion control means) 26 Limiter (saturation processing means) 27 Subtractor (correction means) 28 Multiplier (correction means) 31,32 filter 41 Integral Compensator (Integral Compensation Means) 42 Phase Compensator (Phase Compensation Means)

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-255418 (JP, A) JP-A-10-89459 (JP, A) JP-A-6-102902 (JP, A) JP-A-3- 154902 (JP, A) JP 4-205864 (JP, A) JP 8-142886 (JP, A) JP 6-96545 (JP, A) JP 9-251739 (JP, A) JP 59-32012 (JP, A) Shinsuke Nakagawa and 7 others, Improving disturbance suppression characteristics of magnetic disk devices by anti-windup control, The Japan Society of Mechanical Engineers IIP'98 Lecture on Information, Intelligence and Confidential Equipment Bunshu, Japan, Japan Society of Mechanical Engineers, August 14, 1998, NO. 98-26, 27-29 (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B 21/08-21/10 G11B 7/08-7/10

Claims (5)

(57) [Claims] 1. A coarse actuator and a coarse actuator.
A fine unit fixed to one end of the coarse moving unit driven by the user.
By finely controlling the dynamic actuator,
Positioning of the fine movement part attached to one end of the actuator
In the positioning control device that performs Based on the position error signal supplied from the fine movement unit,
Generates a fine movement control signal for positioning the fine movement unit
Fine movement control means,The coarse actuator based on the fine control signal.
Coarse control means for generating a coarse control signal for supplying to
When, The fine movement control signal is set to the movable range of the fine movement actuator.
Saturation is performed so that it falls within the limit corresponding to
Saturation processing means to supply to the actuator, Difference between the output signal of the saturation processing means and the fine movement control signal
And the subtraction result of the subtractor multiplied by a predetermined constant
CalculateGenerates a correction signal for correcting the fine movement control signal.
CompleteConsisting of a multiplierCompensation means
Characteristic positioning control device. 2. The fine movement control means has an integral compensation means for integral compensation of the fine movement control signal, and changes the internal state of the preceding stage integral compensation means based on the correction signal. 1. The positioning control device according to 1. 3. The fine movement control means has a phase compensation means for phase compensating the fine movement control signal, and changes the internal state of the preceding stage phase compensation means based on the correction signal. 2. The positioning control device described in 2. 4. The sign of the correction signal is the fine motion control signal.
No. If the output signal greater than the saturation processing means,
Feed in the direction in which the internal state of the integral compensation means decreases.
Back is set so that the fine movement control signal is
When it is smaller than the output signal of the saturation processing means, the product
Feedback in the direction that the internal state of the minute compensation means increases
Positioning control apparatus according to claim 2 or 3, wherein that you have been set so that it takes. 5. The coarse actuator is a voice coil.
・ It consists of a motor, and the fine actuator is an electrostrictive element
Made, the coarse portion carriage arm or Rannahli, before
The fine-movement part comprises a magnetic head.
Positioning control apparatus according to any one of 1 to 4.