JPH0632176B2 - Speed control method - Google Patents

Description

DETAILED DESCRIPTION [Overview] A speed control method for positioning a data processing head at a target position, in which a moving speed characteristic in a speed control mode in the vicinity of the target position is defined as an actual speed relative to a target speed. By configuring the speed control circuit so that the error is integrated with the integrated speed error value, overshoot and undershoot during positioning control at the target point are suppressed as much as possible, and quick positioning is possible.

[Industrial application field]

The present invention relates to a speed control method for positioning a data processing head at a target position.

For example, in the magnetic disk device, the data read / write processing is executed for the first time by positioning the data processing head at a predetermined position. Therefore, the positioning of the data processing head is controlled at high speed and with high accuracy. Is required.

[Conventional technology]

FIG. 3 is a block diagram for explaining a conventional example, FIG. 4 is a diagram for explaining speed characteristics, and FIG. 5 is a diagram for explaining positioning control.

FIG. 5 is a block diagram showing the outline of the positioning control in the magnetic disk device, and its configuration is a head 1 for reading servo information and reading / writing data for positioning control to a target point, and positioning. At the time of movement, a speed control mode in which the head 1 is moved to a target track position at a high speed and a position control mode in which the head 1 is accurately positioned at a target point after reaching the target track are controlled by a control unit not shown. A control mode switching unit 2 that switches according to a switching signal, a speed control unit 3 that processes a speed control mode in a positioning process, a position control unit 4 that processes a position control mode in a positioning process, a speed control unit 3 and a position control unit 4 Output from the voice coil motor (hereinafter VCM
6) and a VCM driving section 5 for driving a VCM 6 and a VCM 6.

Both the speed controller 3 and the position controller 4 form a closed loop in terms of circuit configuration.

Since the speed control unit 3 moves to the target track as shown in FIG. 3, a target speed generation unit for generating a target speed according to the moving amount by an access from a part (not shown).
31 and an actual speed measurement / detection unit 32 that detects an actual speed from a servo information signal input from the head 1 via the control mode switching unit 2
And an operational amplifier 33 for obtaining an error (speed error) between the actual speed and the target speed.

The operational amplifier 33 includes an amplifier 33a, resistors R1 to R4 and a capacitor C.

By a positioning control command from a host device (not shown), movement control from a point where the head 1 is currently located to a predetermined point of a target track for reading / writing data is performed by an internal control circuit (not shown). Carry out according to the instructions.

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

Therefore, the VC that drives the actuator (not shown)
The control of M6 becomes the point of the positioning control, and the speed control unit 3 controls the movement from the position where the head 1 is currently located to the target track position where the data is read / written.

That is, the target speed generated from the target speed generation unit 31 and the actual speed detected by the actual speed measurement detection unit 32 are input to the operational amplification unit 33 in the speed control unit 3 and the difference speed between them is calculated and obtained. , Output as speed error.

The VCM drive unit 5 converts this speed error into a value (for example, a current value) to be applied to the VCM6 to control the speed of the VCM6.

[Problems to be solved by the invention]

The characteristic of the actual speed with respect to the target speed in the positioning control by the speed control unit 3 as described above shows the characteristic as shown in FIG.
When positioning to, multiple undershoots and overshoots may be repeated (shown in an enlarged view).

In addition, as one to see the control characteristics in the speed control unit 3,
There is a loop characteristic in the speed control unit 3 as shown in FIG. 4 (B).

The vertical axis of FIG. 4 (B) is the voltage at a predetermined point (for example, point (a) shown in FIG. 3) in the speed control unit 3 (this is the input voltage), and the open loop at that portion. Then, the ratio with the voltage after the predetermined voltage amplification (this is the output voltage) is digitally displayed, and the horizontal axis shows the frequency (logarithmic scale).

Here, the loop characteristic corresponding to the actual speed is shown by the solid line,
In order to reduce the amount of undershoot and overshoot at the positioning point as much as possible, it suffices to increase the level (displayed in decibels) of the low frequency part of the loop characteristic (increase the level as indicated by the chain line). It's already known.

However, if it is set too high, the inrush speed becomes unstable,
Problems such as adversely affecting the positioning control occur.

[Means for solving problems]

 FIG. 1 shows a block diagram illustrating the principle of the present invention.

The principle block diagram shown in FIG. 1 shows the outline of the configuration of the speed control 30. The configuration is the speed error between the target speed for moving to the target track position and the actual speed when the head is actually moving. And a speed error generating means (meaning the operational amplifying section described in FIG. 3) 33 and a speed error value output from the speed error generating means (operational amplifying section) 33 are integrated to obtain a speed error integrated value. Speed error integration means
34, and characteristic correction means 35 for correcting the loop characteristics (shown by the solid line) shown in FIG. 4B with the output value from the speed error integration means 34.
Using the output value from the speed error integrating means 34 for the loop characteristic, the comparing means 36 for comparing and determining whether or not to correct the characteristic by the characteristic correcting means 35 is output from the comparing means 36. It comprises a switching means (electronic switch) 37 for connecting / disconnecting the connection between the speed error integrating means 34 and the characteristic correcting means 35 according to the control signal.

[Action]

If the characteristics of the low-frequency part of the moving speed in the speed control mode near the target position (low-frequency part in the measured degree) are below a predetermined level, the speed error is integrated with the speed error integrated value of the actual speed with respect to the target speed. However, by configuring the speed control circuit so that the correction is not executed when it is above the predetermined level value, the amount of overshoot and undershoot during positioning control at the target point is suppressed as much as possible, and the inrush speed is unstable. The positioning control can be performed in a short time without

〔Example〕

The gist of the present invention will be specifically described below with reference to an embodiment shown in FIG.

FIG. 2 shows a block diagram illustrating an embodiment of the present invention.
The same reference numerals denote the same objects throughout the drawings.

The speed error integrating means 34 in the speed control unit 30 of this embodiment is a part for integrating the speed error, that is, the amplifier 34a and the resistor R.
8, R9 and capacitor C1, and amplifier 34 that amplifies the integrated value
b, resistance values R10 to R12.

Further, the speed error characteristic correction means 35 is placed in parallel with the resistor R13 which is an input resistance of the speed error integration signal from the speed error integration means 34, the resistor R14 which is an input resistance of the speed error, the amplifier 35a and the amplifier 35a. It is composed of a resistor R15 and a resistor R15.

The comparing means 36 compares the speed error with a reference voltage created by dividing the resistors R6 and R7 for creating the reference voltage and the voltages + V and −V with the resistors R6 and R7, and compares the speed error with a predetermined speed error. It is composed of a comparator (CMP) 36a for comparing whether it is small or not.

Further, the switching means (electronic switch) 37 comprises a switch S1 and a switch S2. When the speed error is smaller than a predetermined value, the switch S2 is turned on, and when the speed error is equal to or larger than the predetermined value, the switch S1 is turned on. Becomes

Therefore, when the speed error output from the operational amplifier 33, which is the speed error generating means for obtaining the difference speed between the target speed and the actual speed, is smaller than the predetermined level value, the switch S2 is turned on and the speed error is integrated into the speed error. The velocity error integrated signal created by integrating by the means 34 is input to the characteristic correcting means 35.

As a result, the characteristic correction means 35 corrects the speed error with the speed error integrated signal, and the low frequency part of the loop characteristic is corrected as shown by the dotted line in FIG. 4 (B).

On the other hand, when the speed error is equal to or higher than the predetermined level value, the switch S1 is turned on to discharge the capacitor C1 to prepare for the next operation, and the switch S2 is turned off to remove the characteristic correction means 35.
To function as a simple amplifier, and the loop characteristics are not corrected.

〔The invention's effect〕

According to the present invention as described above, there is an effect that the amount of overshoot and undershoot at the time of positioning control at the target point can be suppressed as much as possible, and that positioning can be performed in a short time.

[Brief description of drawings]

 FIG. 1 is a block diagram illustrating the principle of the present invention, FIG. 2 is a block diagram illustrating an embodiment of the present invention, FIG. 3 is a block diagram illustrating a conventional example, and FIG. 4 is a speed characteristic. 5 and 5 are views for explaining the positioning control, respectively. In the figure, 1 is a head, 2 is a control mode switching unit, 3 is a speed control unit, 3 is a position control unit, 5 is a VCM drive unit, 6 is a VCM, 31 is a target speed generation unit, and 32 is an actual speed measurement. Detecting unit, 33 is operational amplification unit (speed error generating means), 33a, 34a, 34b, 35a are amplifiers, 34 is speed error integrating means, 35 is characteristic correcting means, 36 is comparing means, 36a is comparator (CMP) , 37 indicates switching means, respectively.

Claims (1)

[Claims] 1. A positioning of a target track of a data processing head to a predetermined position is controlled by using a voice coil motor (6) as a driving source, and a movement to the target track position is targeted by the voice coil motor (6). A storage device for positioning to a target track position in a speed control mode for controlling according to a speed and a position control mode for positioning the head at a predetermined point on the target track after moving to the target track. Target speed,
Speed error generating means (33) for generating a speed error from the actual speed when the head is actually moving, and speed error integrating means (34) for integrating the speed error value to obtain a speed error integrated value A characteristic correction means (35) for correcting the loop characteristic of the speed control loop circuit with the output value from the speed error integration means (34), and comparing the speed error value with a predetermined reference value, and the comparison result Is provided as a control signal, and a switching means (37) for turning on / off the switches S1 and S2 according to the control signal output from the comparing means (36). When it becomes smaller than the value, the output from the speed error integrating means (34) is turned on to the characteristic correcting means (35), and the low frequency region of the loop characteristic is changed from the speed error integrating means (34). The speed control method is characterized in that the output value is corrected.