JPH1011924A - Controller for positioning of magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten an access time and improve positioning accuracy at the same time in a magnetic head-positioning controller of a magnetic disk apparatus when executing controls of different target characteristics. SOLUTION: In the magnetic head-positioning controller of a magnetic disk apparatus, a plurality of control systems of different target characteristics are provided and sequentially switched. Moreover, a state estimation device 11 for estimating control information in each control system is shared. A magnetic head 10 is hence positioned to a target cylinder by a seek operation. The controller has a parameter table 15 storing operational parameters of the state estimation device 11. The operational parameters of the parameter table 15 are switched to suit the characteristic of each control system and set in the state estimation device 11.

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, and more particularly to a magnetic head positioning controller for positioning a magnetic head.

2. Description of the Related Art A magnetic head positioning controller of a magnetic disk drive performs control with different target characteristics, such as high-speed speed tracking control and precise positioning control.

In such control of the magnetic head positioning controller having different target characteristics, it is necessary to simultaneously shorten the access time and improve the positioning accuracy.

[0004]

2. Description of the Related Art Conventionally, in a magnetic head positioning controller of a magnetic disk drive, the purpose of improving the head positioning accuracy and shortening the access time has been disclosed, for example, in JP-A-3-030153 and JP-A-3-030156.
And Japanese Patent Laid-Open No. 4-341979.

FIG. 3 shows an example of the configuration of a conventional magnetic head positioning device for a magnetic disk drive, which is described in Japanese Patent Application Laid-Open No. 3-030156.

The magnetic head positioning device of the magnetic disk drive shown in FIG. 3 converts the output signal of the positioning controller 1a from a digital signal to an analog signal into a driving signal (power amplifier drive signal) 8. A D / A converter 6 that outputs a signal, a servo amplifier 7 that amplifies the drive signal 8, an actuator 9 that is a drive source that positions the magnetic head 10 based on the servo output signal of the servo amplifier 7, and the magnetic head 10 reads A position error signal generating circuit 19 for demodulating the position information 17 on the magnetic disk 21 and outputting it as a position signal 2, and an A / D converter 4 for converting the position signal 2 from an analog signal to a digital signal
And an A / D converter 5 for converting the current detection signal 3 from the servo amplifier 7 from an analog signal to a digital signal.

The positioning controller 1a further includes a state estimator 11 for estimating control information, a compensator 12 for precise positioning, a speed controller 13 for high-speed follow-up control, and a control switch 14. ing.

Next, in a conventional magnetic disk drive,
The magnetic head positioning operation will be described. First, the position information 17 on the magnetic disk 21 read by the magnetic head 10 is converted into the position signal 2 demodulated by the position error signal generation circuit 18. The A / D converter 4 outputs the position signal 2
, And the A / D converter 5 discretizes the current detection signal 3 output from the servo amplifier 7. Positioning controller 1
a processes an input signal by a firmware of a digital signal processor (not shown, hereinafter referred to as a DSP), which is one of microprocessors, to generate an output signal.

The output signal of the positioning controller 1a is D / A
After being converted into an analog signal by the converter 6 and held,
The drive signal (power amplifier drive signal) 8 is output to the sabo amplifier 7. The current detection signal 3 output from the servo amplifier 7 drives an actuator 9 also called a voice coil motor (hereinafter, referred to as VCM) to move the magnetic head 10 to a target cylinder (track) on the magnetic disk 21. Move. Positioning controller 1a
, A state estimator 11, a positioning phase compensator 12,
The speed controller 13 and the control switch 14 for switching between the speed following control and the fine positioning control are realized in the firmware (program) of the DSP.

This DSP starts a seek when it receives a seek command from the host device. More specifically, the seek operation is performed by using the speed controller 13 as a seek length information from the current position of the magnetic head 10 to the target position as a seek length information, for controlling a speed following a target speed corresponding to the seek length, and for a positioning phase compensator 12. , Which performs precision positioning control near the target cylinder. The speed following control and the precision positioning control are switched by the control switch 14 when the vehicle reaches the vicinity of the target cylinder. .

The state estimator 11 receives the position signal discretized by the A / D converter 4 and the current detection signal discretized by the A / D converter 5, and performs speed tracking control and precision positioning control. The estimated velocity signal 19 and the estimated external force signal 2 are state estimators that cannot be directly observed.
0 is estimated. The estimation in this case is performed based on the theory of the state estimator of the control theory (the observer of the Re-Emberger).

An outline of the control in this case will be described below. First, a digital model of the control target is created. In this model, the control current is an input, and has external forces, speeds, and positions as internal variables. Simulates in real time the variables when the same input as the actual control target is applied to the model. Since the error diverges due to the difference between the model and the actual control target as it is, the actual measurement position and the estimated position are compared, and the error is fed back to an internal variable so that the error converges. The external force is modeled as an integral of the position estimation error. That is, causes that the model does not match the actual control target are collectively regarded as external force.

The positioning phase compensator 12 inputs the discretized position signal 2 and the estimated speed signal 19 and outputs a control signal so that the control system becomes stable during precise positioning control. The speed controller 13 obtains seek length information from a target cylinder input from a higher-level circuit (not shown), and outputs a control signal proportional to a difference between the target speed from the seek length information and the estimated speed signal 19. .

[0014]

SUMMARY OF THE INVENTION It is an object of a positioning controller for a magnetic disk drive to improve head positioning accuracy and shorten access time.

On the other hand, the magnetic disk drive positioning controller performs positioning control with the magnetic head by switching between high-speed speed tracking control for reducing head access time and precision positioning control for improving head positioning accuracy. . Further, in these controls, what is directly observed are the position information and the driving current, and the head moving speed and the external force applied to the head are estimated by the state estimator.

At this time, in the prior art, the state estimator estimates the state of the estimated speed and the estimated external force according to a fixed pole arrangement regardless of the switching of the control system.

A first problem in this case is that the pole arrangement of the state estimator suitable for the precise positioning control cannot obtain the estimation accuracy required for the high-speed positioning control. The reason is that the pole placement of the state estimator is not high enough,
This is because the estimation of the state estimator is delayed with respect to the movement of the magnetic disk head.

A second problem is that when precise positioning control is performed with a pole arrangement of a state estimator suitable for high-speed tracking control, a large amount of noise components are included in the estimated amount. The reason is that the state estimator excessively reacts to a minute change in state.

As described above, in the prior art, regardless of the switching of the control system, the state estimator performs the state estimation only in accordance with a fixed pole arrangement, so that a plurality of control systems improve the accuracy of each control. Being unable to do so is a common problem.

The present invention is intended to solve such a problem of the prior art, and is intended to achieve the best control accuracy in control having different target characteristics such as high-speed speed follow-up control and precision positioning control. It is an object of the present invention to enable the pole arrangement of the state estimator to be changed every time the control is switched, so that the access time can be reduced and the positioning accuracy can be improved at the same time.

[0021]

According to the magnetic head positioning controller of the present invention, the operation parameters of the state estimator are changed when the control method is switched from the remaining distance to the target cylinder. More specifically, in the magnetic head positioning controller 1 in which a plurality of control systems such as the speed controller 13 and the positioning phase compensator 12 are switched and used by the control switch 14, the estimated speed signal 19 of the state estimator 11 is used. It has a parameter table 15 for storing the operation parameters of the state estimator 11 so that the estimated external force 20 is the most preferable characteristic for each target characteristic, and changes the operation parameter 22 of the state estimator by the control switching signal 16. I do.

Further, in a more specific embodiment of the magnetic head positioning controller of the present invention, there is provided a parameter table in which the pole arrangement of the state estimator is high during the speed control and low during the positioning control.

The magnetic disk device positioning controller performs the positioning control of the magnetic head by switching between high-speed speed following control for shortening the head access time and precise positioning control for improving the head positioning accuracy. further,
The state estimator estimates the head moving speed and the external force applied to the head, which are control information that cannot be directly measured for these controls.

According to the present invention, in control having different target characteristics, such as high-speed speed following control and precise positioning control,
Since the pole arrangement of the state estimator can be changed every time the control is switched so that the control accuracy is maximized, the access time can be reduced and the positioning accuracy can be improved at the same time.

Hereinafter, specific means for solving the problems of the present invention will be described.

(1) A plurality of control systems having different target characteristics are provided, each control system is sequentially switched, and a state estimator 11 for estimating control information in each control system is used in common. In a magnetic head positioning controller of a magnetic disk drive that performs a seek operation for positioning the position of the position of the target cylinder 10 at a target cylinder, a parameter table 15 for storing calculation parameters of the state estimator 11 is provided. The configuration is such that operation parameters suitable for the characteristics of the control system are switched and set in the state estimator 11.

(2) In the case of (1), the parameter table 1
5 stores the operation parameters of a state estimator designed with a high pole arrangement for speed following control, and the operation parameters of a state estimator designed with a low pole arrangement for precision positioning control.

(3) In the magnetic head positioning controller for controlling the positioning of the magnetic head of the magnetic disk drive, a speed controller 13 for performing high-speed tracking control and a positioning phase compensator 12 for performing precise positioning control And a control switch 14 for switching between a control system for high-speed speed follow-up control and a control system for precise positioning control according to the remaining distance to the target cylinder.
And an estimated speed signal and an estimated external force signal are output to the speed controller 13 at the time of high-speed speed follow-up control, and the positioning phase compensator 1 is used at the time of precise positioning control.
2, a state estimator 11 that outputs an estimated speed signal and an estimated external force signal, and calculation parameters of the state estimator 11 in which the estimated speed signal and the estimated external force in the state estimator 11 are the most preferable characteristics for target characteristics of each control system And a parameter table 15 for storing

[0029]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a magnetic head positioning controller according to the present invention. 1, the same parts as those in the conventional example shown in FIG. 3 are denoted by the same reference numerals. In the positioning controller 1 of the magnetic disk drive of the present invention, the positioning controller 1a of the conventional magnetic disk drive is used.
And a parameter table 15 for storing the operation parameters of the state estimator.

The position information 17 on the magnetic disk 21 read by the magnetic head 10 is demodulated by a position error signal generation circuit 18 and converted into a position signal 2. A / D converter 4
Digitizes the position signal 2, and the A / D converter 5 digitizes the current detection signal 3 from the servo amplifier 7. The positioning controller 1 processes these input signals by a DSP firmware (not shown) to generate output signals. The output signal of the positioning controller 1 is converted into an analog signal by the D / A converter 6 and held, and then the drive signal (power amplifier drive signal) 8 is sent to the servo amplifier 7.
Is output as Then, the current detection signal 3 output from the servo amplifier 7 drives the actuator 9 constituted by the VCM to move the magnetic head 10 to a target cylinder (track) on the magnetic disk 21. The DSP is a state estimator 1 that constitutes the positioning controller 1.
1. The operations of a positioning phase compensator 12, a speed controller 13, and a control switch 14 for switching between speed following control and fine positioning control are controlled by firmware.

FIG. 2 is a flowchart showing a process performed by the DSP in this embodiment when the positioning controller seeks. As a part of the positioning controller 1, the state estimator 1
1, a positioning phase compensator 12 for precise positioning, a speed controller 13 for speed following control, a control switch 14 for switching between speed following control and precision positioning control, and a parameter table for storing operation parameters of the state estimator 11 15 is realized in the firmware of the DSP.

Also, the DSP calculates the operation parameters of the state estimator designed to improve the accuracy of the precision positioning control and the parameters of the state estimator designed to improve the accuracy of the speed following control. Parameter table 15
To be stored.

Next, the operation of this embodiment will be described with reference to FIGS.

When the DSP receives a seek command from the host device, the DSP starts a seek operation. At this time, the DSP
The calculation parameters of the state estimator designed to increase the accuracy of the speed following control are fetched from the parameter table 15 and set in the state estimator.

The seek operation is performed by setting the speed controller 1 from the current position of the magnetic head 10 to the target position as seek length information.
3 performs speed follow-up control for the target speed corresponding to the seek length, and performs precise positioning control near the target cylinder by the positioning phase compensator 12. The speed following control and the fine positioning control are switched by the control switch 14 when the vehicle reaches the vicinity of the target cylinder.

At this time, the DSP fetches the operation parameters of the state estimator designed to increase the precision of the precision positioning control from the parameter table 15 and sets them in the state estimator 11.

The state estimator 11 receives the position signal discretized by the A / D converter 4 and the current detection signal discretized by the A / D converter 5, and performs speed tracking control and precision positioning control. The estimated speed signal 19 and the estimated external force signal 20, which are unobservable state estimators used for
Is estimated and output.

At this time, the positioning phase compensator 12 inputs the discretized position signal 2 and the estimated speed signal 19 and outputs a control signal so that the control system becomes stable during the precise positioning control. The speed controller 13 obtains seek length information from a target cylinder input from a higher-level circuit (not shown), and outputs a control signal proportional to a difference between the target speed from the seek length information and the estimated speed signal 19. .

Next, a description will be given of a design method for increasing the accuracy of the follow-up control and a design method for increasing the accuracy of the precision positioning control for the operation parameters of the state estimator stored in the parameter table 15.

First, in the speed following control, the pole arrangement of the state estimator is set sufficiently high so that the estimation of the state estimator does not become slow with respect to the movement of the magnetic disk head.

In the precise positioning control, the state estimator excessively reacts to a minute change in state,
The pole arrangement is set low so as not to include a large amount of noise components in the estimator, so that an estimation error larger than the required positioning accuracy does not occur, and the time required to settle to a correct state estimator is shortened.

In this way, the operation parameters of the state estimator are designed so as to be the most preferable characteristics for the respective target characteristics in the control having different target characteristics, such as high-speed speed tracking control and precision positioner control. Therefore, it is possible to change the pole arrangement of the state estimator every time the control is switched, so that it is possible to simultaneously shorten the access time and improve the positioning accuracy.

[0044]

As described above, according to the present invention, in a magnetic head positioning controller for a magnetic disk drive,
Shortening of access time and improvement of positioning accuracy can be realized at the same time. This is because, in the present invention, in the control having different target characteristics such as high-speed speed tracking control and precise positioning control, the pole arrangement of the state estimator is changed for each control change so as to be the most preferable characteristic for each target characteristic. To change it.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a magnetic head positioning controller of the present invention.

FIG. 2 is a flowchart illustrating a process performed by a DSP when a positioning controller seeks according to the embodiment;

FIG. 3 is a block diagram showing a configuration example of a magnetic head positioning device of a conventional magnetic disk drive.

[Explanation of symbols]

 1, 1a Positioning controller 2 Position signal 3 Current detection signal 4, 5 A / D converter 6 D / A converter 7 Servo amplifier 8 Drive signal (power amplifier drive signal) 9 Actuator 10 Magnetic head 11 State estimator 12 Positioning Phase compensator 13 Speed controller 14 Control switch 15 Parameter table 16 Control switch signal 17 Position information 18 Position error signal generation circuit 19 Estimated speed signal 20 Estimated external force signal 21 Magnetic disk 22 Operation parameter of state estimator

Claims (3)

[Claims] 1. A magnetic head comprising a plurality of control systems having different target characteristics, sequentially switching the control systems, and commonly using a state estimator for estimating control information in each control system. In a magnetic head positioning controller of a magnetic disk drive that performs a seek operation for positioning to a target cylinder, a parameter table for storing operation parameters of the state estimator is provided, and a parameter table for each control system is obtained from the parameter table according to each control system. A magnetic head positioning device characterized in that calculation parameters suitable for characteristics are switched and set in the state estimator. 2. In the parameter table, calculation parameters of a state estimator designed with a high pole arrangement for speed following control and calculation parameters of a state estimator designed with a low pole arrangement for precision positioning control 2. The magnetic head positioning controller according to claim 1, wherein 3. A magnetic head positioning controller for controlling the positioning of a magnetic head of a magnetic disk drive, comprising: a speed controller for performing a high-speed tracking control; a positioning phase compensator for performing a precise positioning control; A control switch for switching between a control system for high-speed speed follow-up control and precision positioning control in accordance with the remaining distance to the cylinder; And a state estimator that outputs an estimated speed signal and an estimated external force signal to the positioning phase compensator at the time of precise positioning control, and the estimated speed signal and the estimated external force in the state estimator are determined in advance for the target characteristic of each control system. And a parameter table for storing operation parameters of the state estimator that are determined most preferable characteristics. A magnetic head positioning controller.