JPS6398884A - Positioning control system - Google Patents

Abstract

PURPOSE:To early suppress fluctuation and vibration at a positioning point by feeding back a current flowing to a voice coil motor to a loop circuit of the position control mode just after changeover to the position control mode to correct the positioning control mode characteristic. CONSTITUTION:The positioning of a data processing head on a prescribed position of an objective track is controlled by the drive of a voice coil motor (VCM) 6. Just after the control is switched from the speed control mode to the position control mode, a current flowing to the VCM 6 is integrated and fed back to the loop circuit of the positioning control mode by a current integration means 48 and a changeover control circuit 49. When the head positioning control is switched to the position control mode, the current integration means 48 is incorporated into the position control mode by the means 49 and the current integrated by the current integration means 48 is adjusted by a current flowing to the VCM 6 to feed back it to the loop circuit of the position control mode. Thus, the generation of overshoot/undershoot at an objective point is suppressed to the utmost.

Description

[Detailed Description of the Invention] [1 Already Required] A control method for positioning a data processing head to a target position, in which a speed control system is used in the vicinity of the target position for positioning the head. In order to solve the problem that a lot of fluctuations and vibrations occur at the positioning point depending on the situation when switching from ff1l mode to position control mode, the current flowing through the voice coil motor is changed to the position control mode immediately after switching to position control mode. Return to the loop circuit,
By configuring the position control mode characteristics to be corrected, fluctuations and vibrations at the positioning point can be suppressed at an early stage.

[Field of Application in Industry-1-] The present invention relates to a control system when positioning a data processing head to a target point.

For example, in a magnetic disk device, data reading/writing processing is executed only after a data processing head is positioned at a predetermined position.

Therefore, positioning the data processing head at high speed and with high precision is required in order to efficiently use a data processing system that processes data by connecting a magnetic disk device. .

[Prior Art] FIG. 3 is a block diagram for explaining a conventional example, FIG. 4 is a diagram for explaining positioning control characteristics, and FIG. 5 is a diagram for explaining positioning control.

FIG. 5 is a block diagram showing an overview of positioning control processing in a magnetic disk device, and its configuration includes a head 1 that reads servo information and reads/writes data to perform positioning control to a target point; During positioning movement, there is a speed control mode in which the head 1 is moved at high speed to the target track position, and a position control mode in which the head 1 is accurately positioned at the target point after reaching the target track.The control method is not shown in the figure. Is there a system in which switching is performed using a switching signal from? lIl mode switching unit 2; a speed control unit 3 that processes the speed control mode in positioning processing; a position control unit 4 that processes the position control mode in the positioning process; and outputs from the speed control unit 3 and the position control unit 4. , voice coil motor (hereinafter referred to as VC), which is the drive source for positioning operation.
11) 6) and the VCM drive unit 5 and the VCM
6.

In addition, the circuit configuration of the speed control section 3 and the position control section 4 is as follows.
It forms a closed loop.

Further, as shown in FIG. 3, the position control unit 4 includes a position signal generation circuit 42 that generates a position signal ■ based on a demodulated signal ■ that is obtained by demodulating the servo information in a demodulation circuit 7 that demodulates the servo information read by the head 1; This is a circuit in which a filter is composed of an amplifier, and includes a position error creation circuit 43 that creates a position error signal ■ from an input position signal ■, and an amplifier 44 that amplifies the position error signal ■ output from the position error creation circuit 43 to a predetermined value. , an integrating circuit 45 that integrates the position error signal ■, a differentiation circuit 46 that differentiates the position error signal ■, and an amplifier 44 . The signals sent from the integrating circuit 45 and the differentiating circuit 46 are combined to form a position control signal VC? Amplifier 4 sending out data to I drive unit 5
7.

The head 1 is mounted on an actuator (not shown) driven by a VCM 6, and is positioned at a predetermined point on a target track by movement of the actuator (not shown).

Therefore, V driving the actuator (not shown)
The control of CM6 is the key point of positioning control, and the position control section 4 controls the speed side? Controlling the operation of inheriting the state information at the mode switching point from the in section 3 and positioning the head 1 to a predetermined point on the target track where data is to be read/written? Do IB.

That is, in the position side j11 section lt internal position error generation circuit 43, the device signal (2) constituted by the position signal generation circuit 42 during movement of the head 1 passes through an internal filter and is sent out as a position error signal (2).

This position error signal ■ is sent to the vcFI drive unit 5 as a position control signal ■ by the amplifier 44, 47, etc.
The head 1 is positioned by being driven.

[Problem that the invention seeks to solve]

The characteristic curve of the apparatus error signal (2) composed of the position error generating circuit 43 in the position control section 4ff11 section 4, which is a double series, is as shown in FIG. 4(A).

In addition, there is an open loop characteristic (solid line curve) as one of the closed loop characteristics, tracking error characteristics, etc. used to evaluate the characteristics of the position control unit 4, and it is determined by the position error signal ■ as shown in FIG. It is displayed as voltage gain (vertical axis) versus frequency (horizontal axis).

This is the voltage at a predetermined point in the position side 2111 section 4 (for example, the (al point) shown in FIG. is the output voltage) expressed in decibels, and the horizontal axis is the frequency expressed in logarithms.

The solid line curve characteristic in FIG. 4(B) indicates an open loop characteristic with a predetermined phase, and the evaluation of loop stability is as follows:
θ. is large, the fθ=0 point is also large, and fo is as high as possible to obtain a loop characteristic with quick response.

However, it is currently impossible to eliminate mechanical resonance of about 177 to 178 or more from an actuator (not shown) or the like due to the stability of the loop.

Therefore, for example, if the speed control mode is switched to the position control mode at a point where there is a large error with the target point, the fluctuation of the position signal ■ will not be reduced easily, resulting in overshoot or undershoot at the positioning point (see Figure 4). A
)) is more likely to occur.

[Failure to solve the problem]

FIG. 1 shows a block diagram illustrating the invention in detail.

The principle block diagram shown in FIG. 1 shows an outline of the configuration of the position side J%'0, which consists of the functional blocks 44 to 47 explained in FIG. VCM
a current integrating means (current integrating circuit) 48 that integrates the current flowing through the circuit 6 and feeds it back to the loop circuit in the position control mode; switching control that controls switching of the current integration means (current integration circuit) 48 and adjustment of the integrated current value output from the current integration means (current integration circuit) 48 by comparing the detected value of the current integration means (current integration circuit) 48 with a predetermined value; Means (switching control circuit) 49 and switching control means (switching control circuit) 4
The system of 9? Switches 81 to S turned on/off by 111
4.

[Effect]

Immediately after switching from the speed control mode to the position control mode in the vicinity of the target position, the current flowing through the VCM 6 is integrated by the current integration means (current integration circuit) 48, and the current integral value is controlled to enter the position control mode loop. By returning and correcting the loop characteristics during the loop in position control mode and controlling the loop system to increase damping, it is possible to suppress fluctuations and vibrations in the position signal at the positioning point to (early) ■ becomes.

〔Example〕

The gist of the present invention will be specifically explained below with reference to embodiments shown in FIGS. 1 and 2.

FIG. 2 shows a block diagram illustrating the invention in detail. Note that the same reference numerals indicate the same objects throughout the figures.

The current integration circuit 48 in the position control section 40 of this embodiment is composed of an amplifier 48a, a resistor R481, and a capacitor C18.

The amplifier 44 in the position control section 40 includes an amplifier 44a and resistors R441 to R443, and the integrating circuit 45 includes an amplifier 45a.
, resistors R451, 452, capacitors C, i5, differential circuit 16 is an amplifier 46a, resistance values R461 to R
463 and a capacitor 046°47.

Further, switches 81 to S4 controlled by the switching control circuit 49
When in speed control mode, switches SL, S2 . S4 is on, and the integration circuit 45 and the current integration circuit 48
7. It is poisonous that the function has stopped.

Next, immediately after switching from the speed control mode to the position control mode, the switch S4 is turned on depending on the state of the position error signal ■ and the state of the signal ■ that feeds back the state of the VCM6, and the switch S3 is turned on. There are cases.

Turning on the switch S4 means correcting the loop characteristic (C) and (d1 part) in FIG. 4(B) as shown by the dotted line, and correcting so that θ. means.

On the other hand, turning on switch S3 means that the loop characteristic (0
1 and (r) are corrected as shown by dotted lines.

The switching control circuit 49 compares the position error signal (■) with an internally stored position error reference value, and turns off the switches S3 and S4 by control signals (b) and (c) when a predetermined error value is reached. .

Also, depending on the state value of the position error signal ■ and the state of the signal ■ that feeds back the state of the VCM6, the control signal (b) is used to turn on the switch S3, and the control signal (b) is used to turn on the switch S4. c) will be controlled.

By controlling the position control motor loop as described above, it is possible to quickly stabilize the position signal (2).

〔Effect of the invention〕

According to the present invention as described above, it is possible to quickly suppress the instability of the position signal immediately after switching to the position control mode, and to suppress the occurrence of overshoot and undershoot at the target point as much as possible. effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram explaining the present invention in detail, FIG. 2 is a block diagram explaining the present invention in detail, FIG. 3 is a block diagram explaining a conventional example, and FIG. 4 is a block diagram explaining positioning control characteristics. 5 and 5 are diagrams illustrating positioning control, respectively. In the figure, 1 is a head, 2 is a control mode switching section, 3 is a speed control section, 4 and 40 are position control sections, and 5 is a VCM
Drive unit, 6 is VCM, 7 is demodulation circuit, 4
2 is a position signal generation circuit, 43 is a position error generation circuit, 44
．． 47 is an amplifier, 45 is an integration circuit, 46 is a differentiation circuit, 48 is a current integration circuit, 49 is a switching control circuit,
44a, 45a, 46a, and 48a indicate amplifiers, respectively.柁 Kaifu

Claims (1)

[Scope of Claims] The positioning of the data processing head to a predetermined position on a target track is controlled through the drive of a voice coil motor (6), and the head is moved to the target track position according to a target speed. and a position control mode in which the head is positioned at a predetermined point on the target track after moving to the target track. Immediately after the switching, a current integrating means (48) integrates the current flowing through the voice coil motor (6) and feeds it back to the loop circuit in the position control mode, and a current integrating means (48) integrates the current flowing through the voice coil motor (6) and feeds it back to the loop circuit in the position control mode; At the same time, the current value flowing through the voice coil motor (6) is compared to determine whether or not the current integrating means (48) can be incorporated into the position control mode loop circuit, and the current integrating means (48) a switching control means (49) for controlling the adjustment of the integrated current value output from the switching control means (49);
9) switches (S1 to S4) that are turned on/off under the control of
), and when the positioning control of the head is switched to the position control mode, the current integration means (48) is incorporated into the position control mode by the switching control means (49), and the current integration means (48) is incorporated into the position control mode. ) is adjusted by the current value flowing through the voice coil motor (6) and fed back to the loop circuit in the position control mode.