JP2615521B2 - Positioning control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the positioning of a recording / reproducing head in an information storage device such as a magnetic disk device and an optical disk device .
The present invention relates to a method for adjusting a gain of a compensator .

[0002]

2. Description of the Related Art A positioning control method for a disk drive includes a seek mode in which a recording / reproducing head is moved at a high speed toward a target track, a settling mode in which a transient positioning operation is performed subsequently, and a stationary mode for a target track. The following mode can be divided into a following mode in which a typical following operation is performed. The switching from the seek mode to the settling mode and the switching from the settling mode to the following mode are performed based on a predetermined reference value in which at least one of the remaining distance between the head and the target track or the relative moving speed of the head with respect to the recording disk is determined. Perform when the following occurs.

A positioning control system in a conventional positioning control method for a disk drive uses a proportional term, ie, a P term for adjusting a loop gain of the positioning control system, and a loop stability to compensate for the loop characteristics. , And a PID compensator composed of an integral term for reducing the steady-state deviation, ie, an I term. Embodiments of the PID compensator provide each of the P, I, and D terms in parallel,
There are various methods such as providing a P-term and an I-term in parallel and providing a D-term in the form of a phase compensation filter such as a lead-lag filter on the output side, but it is generally known as a PID control method. The operating point of this positioning control system, that is, the loop gain, is set so as to secure a steady loop stability in the following mode. The configuration and operating point of this PID compensator are used without change even in the settling mode. .

[0004]

However, in the conventional positioning control system, the PID compensator and the operating point for loop characteristic compensation are commonly used in the settling mode and the following mode. The operating point is fixed, and the response performance in the settling mode is limited.

The present invention has been made to solve such a problem, and an object of the present invention is to observe a position signal waveform in a settling mode in a positioning control system of a disk drive. It is an object of the present invention to provide a positioning control method capable of improving a quick response by determining a gain of a compensator in a position control loop based on the result.

[0006]

Means for Solving the Problems The present invention for solving the above problems includes a following operation modes to follow a settling mode for positioning a workpiece relative to a target position to the target position, the settling mode the step of observing the position error signal waveform of the target position and the target object, performing a compensation calculation of the positioning control loop for positioning or tracking the object with respect to the target position, the position deviation signal Judging that it is below the predetermined reference value and going to the following mode
Switching , said following mode
That the step of the position deviation signal waveform waveform analyzing, determining a compensation gain based on the waveform analysis, and a step of setting the compensation gain compensator, wherein the step of waveform analysis, switched to the settling mode Overshoot time from when the position deviation signal overshoots to the first peak value, and a step of obtaining an overshoot amount from the target position at that time, the step of obtaining the compensation gain, The compensation is performed based on at least one of comparing the overshoot time with a predetermined reference value of the overshoot time, or comparing the overshoot amount with a predetermined reference value of the overshoot amount. A step of increasing or decreasing the gain.

[0007]

As described above, the present invention determines the gain of the compensator for shortening the settling time with a simple configuration without greatly changing the configuration of the positioning control system in the settling mode, and using this to determine the responsiveness. Can be greatly improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a block diagram of a positioning control device according to one embodiment of the present invention. 1 is a disk on which data and position servo signals are recorded in a data area 8 and a servo area 9, respectively. 2 is a head for reading and writing data and position servo signals on the disk 1. 3 is a head for moving the head to a desired location on the disk 1. Actuator to move,
4 is a current driver for applying a drive current to the actuator 3; 5 is a position detecting means for detecting a position signal X based on a signal obtained from the head 2; 7 is a digital value converted to an analog value and time discrete data is converted. A D / A converter having a holding function, 10 is an integrator for increasing the low-frequency gain of the position control loop 6, 11 is an integral gain adjuster for adjusting the integral gain, and 12 is the position control loop 6. Differentiator to ensure loop stability of
3 is a differential gain adjuster for adjusting the differential gain, 1
4 is a proportional gain adjuster for adjusting the loop gain of the position control loop 6, 15 is an addition for adding the output signal SI of the integrator 10, the output signal SD of the differentiator 12, and the output signal RP of the proportional gain adjuster 14. And 16 are waveform observers for observing the position signal waveform and outputting adjustment command signals to the integral gain adjuster 11, differential gain adjuster 13, and proportional gain adjuster 14 based on the result. It comprises an analyzer 18. Reference numeral 19 denotes a microcomputer that performs control calculations such as integration, differentiation, and addition, and waveform observation and gain adjustment.

FIG. 2 is a flowchart showing the procedure of each mode of seek, settling, and following in the positioning control method according to one embodiment of the present invention. When a seek command is received from an external device and the mode is shifted to the seek mode (step 1), a drive command is output to the actuator (not shown). At the same time, the number of remaining tracks and the moving speed are measured (not shown), and when each of them becomes a certain value or less, the mode is switched to the settling mode (step 2).

In the settling mode, first, the position signal X is observed by the waveform observer 16 and stored in the waveform memory 17 (step 3). Next, a control operation is performed by the microcomputer 19 (step 4). The control operation is performed by multiplying the position signal X by an integral gain AI, a differential gain AD, and a proportional gain AP (hereinafter collectively referred to as a compensation gain) to obtain registers RI,
Inputting the values to the registers RD and RP; integrating the value of the register RI and inputting the values to the register SI;
And inputting the result to the register SD, and adding the value of the register SI, the value of the register SD, and the value of the register SP to the register U.

Next, it is determined that the position signal X has become equal to or less than a certain reference value X0 (step 5), and the mode shifts to the following mode (step 6). In the following mode,
While performing control calculations necessary for following (not shown), the data stored in the waveform memory 17 is stored in the waveform analyzer 1.
8, new compensation gains AIN, ADN, and APN are obtained based on the results, and the respective values are registered in the register AI of the integral gain adjuster 11, the register AD of the differential gain adjuster 13, and the proportional gain adjuster 14. (Step 8). Thereafter, a seek command is waited in the following state, and when the seek command is received, the mode shifts to the seek mode again. New compensation gay found in the above process
AIN, ADN, and APN are the set
Used in the switching mode. Similarly, seek mode
Mode, settling mode and following mode
While updating the compensation gain.

Next, a method of waveform analysis and a method of determining a compensation gain will be described. FIG. 3 is a time response waveform diagram of the moving distance of the actuator in the positioning control method according to one embodiment of the present invention. FIG. 7A shows the process from the start of the movement to the movement to the target position. FIG. 2B is an enlarged view of the settling portion of FIG. In FIG. 3B, TSTL is the time from when the settling mode is switched to when the response waveform overshoots to the first peak value, and HSTL is the amount of overshoot from the target position at that time. The waveform analyzer 18 includes the TSTL and the HSTL
Are detected as parameters, and these values are compared with predetermined reference values TSTL0 and HSTL0, and a compensation gain determination method described below is used.

The method of determining the compensation gain is performed by two methods. One is a method of determining the integral gain AI while keeping the proportional gain AP and the differential gain AD constant. That is, as a result of the waveform analysis, the parameter HSTL is not much larger than the reference value HSTL0, but the parameter TSTL is smaller than the reference value TSTL0.
If the value is extremely large as compared with, the integral gain is determined to be insufficient, and the integral gain AI is increased.

The other is a proportional gain AP and an integral gain AI.
Is a method in which the differential gain AD is determined while keeping the constant. That is, as a result of the waveform analysis, the parameter TSTL becomes the reference value TSTL0.
However, when the parameter HSTL is extremely large compared to the reference value HSTL0, the differential gain, that is, damping is determined to be insufficient, and the differential gain AD is increased. These two methods are appropriately combined and executed, and the proportional gain AP is finally changed for the purpose of finely adjusting the loop gain. All of these round steps are performed within a range that does not impair loop stability.

Next, a method of determining the integral gain AI while keeping the proportional gain AP and the differential gain AD constant among the methods of determining the compensation gain will be described.

FIG. 4 is an enlarged view of the settling portion of the time response waveform of the movement distance of the actuator in the positioning control method according to one embodiment of the present invention. 41 is an integral gain AI
Is the default value AI0, and reference numeral 42 is the case where an integral gain AIN larger than the default value AI0 is given as a result of the waveform analysis. T1 and T2 indicate the points in time when the remaining distance from the target position becomes equal to or less than the specified value X0 (for example, 1 μm) in the responses of 41 and 42, respectively.
It can be seen that No. 2 reached the target position earlier, and the responsiveness was significantly improved.

FIG. 5 is an open-loop frequency response characteristic diagram of the positioning control system in the positioning control method according to one embodiment of the present invention. Reference numerals 51 and 52 denote gain characteristics and phase characteristics when the integral gain AI is the default value AI0. And 53, 54
Indicates gain characteristics and phase characteristics when the integral gain AI is AIN. When the integral gain AI is AIN, the phase characteristics are worse than in the case of AI0, but the gain characteristics are increased as a whole, and the response is improved.

Further, among the methods for determining the compensation gain, the proportional gain AP and the integral gain AI are kept constant and the differential gain AD is determined.
The method for determining is described.

FIG. 6 is an enlarged view of the settling portion of the time response waveform of the moving distance of the actuator in the positioning control method according to one embodiment of the present invention. 61 is the differential gain AD
Is a case where the differential gain ADN is larger than the default value AD0 as a result of the waveform analysis. T3 and T4 indicate the point in time when the residual distance from the target position becomes equal to or less than the specified value X0 (for example, 1 μm) in the responses of 61 and 62, respectively.
It can be seen that No. 2 reached the target position earlier, and the responsiveness was significantly improved.

FIG. 7 is an open-loop frequency response characteristic diagram of the positioning control system in the positioning control method according to one embodiment of the present invention. Reference numerals 71 and 72 denote gain characteristics and phase characteristics when the differential gain AD is the default value AD0. 73, 74
Indicates gain characteristics and phase characteristics when the differential gain AD is ADN. When the differential gain AD is ADN, the low-frequency gain characteristic is lower than when AD0, but the peak of the phase characteristic moves to a lower frequency side (peak 2). When the phase characteristic is lowered due to the hold delay, the ADN has a larger phase margin at the operating point, and the responsiveness is improved.

[0022]

According to the present invention, the following effects can be obtained by the configuration described above.

In the settling mode, it is possible to determine the gain of the compensator for shortening the settling time with a simple configuration without greatly changing the configuration of the positioning control system, and to use this to greatly improve the responsiveness. .

Although the above embodiment has been described by taking a magnetic disk device as an example, the present invention is also applicable to an optical disk device and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram of a positioning control device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the procedures of seek, settling, and following modes in a positioning control method according to an embodiment of the present invention.

FIG. 3A is a time response waveform diagram of an actuator moving distance in a positioning control method according to an embodiment of the present invention; FIG. 3B is a time response of an actuator moving distance in a positioning control method according to an embodiment of the present invention; Enlarged view of settling part of waveform

FIG. 4 is a time response waveform diagram of the moving distance of the actuator in the positioning control method according to one embodiment of the present invention.

FIG. 5 is an open-loop frequency response characteristic diagram of a positioning control system in the positioning control method according to one embodiment of the present invention.

FIG. 6 is an enlarged view of a settling portion of a time response waveform of a moving distance of an actuator in the positioning control method according to one embodiment of the present invention.

FIG. 7 is an open-loop frequency response characteristic diagram of a positioning control system in the positioning control method according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc 2 Head 3 Actuator 4 Current driver 5 Position detection means 6 Position control loop 7 D / A converter 8 Data area 9 Servo area 10 Integrator 11 Integral gain adjuster 12 Differentiator 13 Differential gain adjuster 14 Proportional gain adjuster 15 adder 16 waveform observer 17 waveform memory 18 waveform analyzer 19 microcomputer

Claims (2)

(57) [Claims] 1. A settling mode for positioning an object with respect to a target position and a following mode for following the target position, wherein the settling mode represents a position deviation signal waveform between the object and the target position. the step of observing, performing a compensation calculation of the positioning control loop for positioning or tracking the object with respect to the target position, it is determined that the position deviation signal is less than the reference value determined in advance the Following mode
Switching to the following mode.
De, the step of waveform analyzing the position deviation signal waveform,
Obtaining a compensation gain based on this waveform analysis, and setting the compensation gain in a compensator, wherein the waveform analysis step is performed after the position deviation signal overshoots after the mode is switched to the settling mode. Overshoot time to peak value,
Determining the amount of overshoot from the target position at that time, and determining the compensation gain comprises comparing the overshoot time with a predetermined reference value of the overshoot time, or A positioning control method comprising: increasing and decreasing the compensation gain based on at least one of a comparison between a shoot amount and a predetermined reference value of the overshoot amount. 2. A compensation calculation, the step of performing integral calculation by multiplying the integral compensation gain to the position deviation, the step of performing a differential operation by multiplying the differential compensation gain to the positional deviation, multiplied by a proportional compensation gain on the position error performing a proportional compensation, comprising the step of adding the proportional compensation output and the integral operation output and the differential operation output, obtains a compensation gain
The overshoot time and the overshoot
The integration compensation gay based on a comparison with the reference value of the gate time.
Step to increase or decrease the amount of overshoot or the amount of overshoot
Based on the comparison of the overshoot amount with the reference value.
At least one of the steps to increase or decrease the differential compensation gain
2. The positioning control method according to claim 1 , further comprising :