JPS59198572A - Magnetic head positioning control system - Google Patents

Abstract

PURPOSE:To prevent generation of overshoot attended with seek operation of a magnetic head by decreasing a feedforward control signal at each prescribed period in response to a speed profile after the magnetic head approaches a prescribed distance to a required position. CONSTITUTION:This invention relates to the feedforward signal profile as shown in figure by decreasing sequentially a feedforward signal in response to the period of calculation. When an observing signal (position error signal or deceleration start command signal or speed profile signal) is inputted to an input terminal IN, the signal is inputted to a CPU29 via an A/D converter 28. The CPU29 judges whether or not the feedforward value (FF value) set in advance in an ROM30 is outputted and has a function to output the FF value. When the condition to reduce the FF value is satisfied, the FF value is reduced stepwise after that time so as to attain the feedforward signal profile of tD<t<tC'. Further, Fig. A shows the feedforward sgnal and Fig. B indicates the speed profile signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical field of the invention The present invention relates to head positioning II in a magnetic disk drive.
A suitable seek splitting method is developed by using the J@coupling method to stabilize high-speed seek operations.

(b) Conventional technology and problems A follow-up example will be explained along the diagram.

FIG. 1 is a 70-step diagram of a conventional magnetic head seek control system. 1 is a disk device, 2 is a disk, and 3 is a magnetic head. A linear driver 4 moves the magnetic head 3 to a desired position on the disk 2. During the moving seek operation, the W negative signal 6 obtained from the magnetic head 3 is converted to a position (8) by the decoder 5.Then, the signal 7 is differentiated by the differentiator 8 and becomes a velocity signal 11. .A speed error signal 15 is generated as the difference between the foot-banked speed signal 11 and the speed flow file 812 generated by the command signal generator 21 through the subtractor 13.

The signal is sent to the power amplifier 18 through the phase compensation circuit 17 and drive control of the linear driver 4 is performed.

In addition, in order to realize a high-speed and stable seek operation, in parallel with this footbatter control, a feedforward error 19 generated by a feedforward signal generator 20 is added to the speed error 41 15 via a summing amplifier 14. Feedforward control is often performed.

This feeder current 19 can be considered to be an ideal current that should flow through the main body 14 when the magnetic head 3 moves according to the velocity profile signal 12.

A position error signal 823, which is the difference between the signal 7 and the signal 7, is generated via the lever 9. 22 is a deceleration start determination circuit that starts deceleration when the position error value reaches a predetermined value, that is, when it is detected that the magnetic head approaches the desired position by a predetermined ratio of 1111 fK. This is an explanatory class of an example of a circuit that outputs the command value 24 and inputs it to the command P generator 21 and the feedforward H7 generator 20, where (M) indicates a feedforward signal. In other words, it shows the change in the feedforward signal when acceleration and deceleration of the magnetic head 3 is performed by constant current driving, and if the Y-axis is feet 7 ond times + 1 (that is, acceleration) and the X-axis is time, then K is shown in the figure. (+ (t;
It is accelerated by the sail at ≦1A.

When tA<t≦tB, it moves at a constant speed, and when tB (t≦t, 2, it is decelerated in winter.In this case, the velocity flow file V in direction 1 during deceleration is the ratio of acceleration for deceleration α・,magnetic The position error between the current position of the head and the 1st position is 7.
"" 2 (represented by Z
Make 2.

Figure 2 (,B) shows the velocity flow file V, and if the maximum velocity of the magnetic head 3 is Vo, then the velocity solo file V
The improvement with respect to the time axis is @m(v-~0-αt), which is represented by the dashed line and actual record.

In these various conventional seek systems @ yarn, the maximum speed of the magnetic head 3 is V. If the average access time is not very large, there is no problem, or if you want to reduce the average access time by 9ji, that is, if you increase the maximum speed of the magnetic head 3, the actual speed of the magnetic head 3 during deceleration may be affected by factors such as inertia. Due to this, knitting phenomenon occurs due to insufficient deceleration (-A-Pursuit)
was likely to occur.

FIG. 3 shows a circuit diagram of a conventional feed 7oF (N7 generator). In the figure, 25a to 25.l are resistors.

26 is a switching transistor, and 27 is an amplifier.

EB is the video terminal, IN is the input terminal and deceleration start command @Jp
! '24 has been input. OUT is an output terminal and has a circuit configuration that outputs a feed forward signal 19. That is, the switching transistor 26 is turned ON and OFF by the deceleration start command (Q 24), thereby obtaining a constant feedforward signal 19. In such a configuration, until the final time tQ of deceleration shown in FIG. Since the deceleration is a constant value, there is a drawback that overshoot cannot be prevented.

(c) Purpose of the Invention The present invention addresses the above-mentioned conventional drawbacks and provides a magnetic head that can prevent the occurrence of automatic shoots associated with seek operations of magnetic heads.
The purpose is to provide a \end positioning control system.

(d) Structure and object of the invention According to the present invention, there is provided a magnetic head positioning control method in which a magnetic head is positioned at a desired position of a magnetic tape according to a velocity flow file using feedforward control. This is achieved by providing a magnetic head positioning control method characterized in that after approaching a predetermined distance to a desired position, the feedforward control signal is reduced at regular intervals in accordance with the speed profile. .

(e) Embodiment of @Ming Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 4 to 6. In each section, parts corresponding to those in Figures 1 and 2 are designated by the same reference numerals, and the explanation of the electric board is omitted.
A) is a feedforward signal.

(B) shows a speed profile signal.

No. 4 [8i (A)] corresponds to Fig. 2 (A).

In order to prevent automatic shoot, the drive current of the driver 4, that is, the feedforward signal 19, is changed to the maximum feed stage tD""t of 1"Itn"tc during deceleration as shown in the figure.
A possible method is to decrease the amount of time C in proportion to time.

In this method, the fourth change in the speed flow 7 isle multiple 12 with respect to the time axis shown in 1(B) becomes a quadratic curve as shown in the figure box at the final stage t,, -tc' of the deceleration time, and the seek At the final stage of operation, the magnetic head 3 speeds up slowly and overshoot is less likely to occur.

The present invention uses a digital calculation system to move the feet 7, 1, 2, and 3 in a few steps according to the counting period.
The method for reducing the feed 7 Owart flow file as shown in FIG. 4 will be described below.

FIG. 5 shows a feedforward signal generation circuit of the first method of dividing the magnetic head positioning according to the present invention.

In the figure, 19a is a feedforward signal, 28 is A
/D friend (So-equipment, 29 is CPU, 3tl is ROM,
31 is D/A-hen K, vessel, 32 is sample board pick, 331d
Hold mechanism, N indicates the input terminal, and OUT indicates the output terminal.

Input terminal IC observation (-position error 23 or deceleration start command (i4 course 24 or speed flow signal 12)
) is input, it is converted into a digital signal by the A/D converter 28 and input to the next CPU 29.

Further, the feed forward program shown in FIG. 6 is distributed to the 30 ROMs. That is, the CPU 29 determines whether or not to output the ROM 3 (feedforward value (hereinafter abbreviated as F'F value) set in advance to +) into which the observation signal is input. It has the function of disconnecting l'lJ and outputting the FF value. Further, when the conditions for decreasing the FF value are satisfied, the FF value is decreased stepwise thereafter, and the feedforward signal flow profile of tD<t<tc' in FIG. 4 is achieved.

The condition for starting the FF value decrease is position error @”J’ 23
may be used, or the speed profile signal 12 may be used. Feedforward signal 19 outputted from CPU 29. Sunful Neyoko 32 and Ho; 4 Do Sakurasa 33
This results in a ripple held value. Further, the rate at which the FF value is reduced in each calculation cycle (the value of FP in FIG. 6) is determined from the initially set feedforward signal flow file and the calculation cycle execution time Δt. For example, l tc'tDl = 8+++seC, △t?
2+107+111eC+1aAl=FF initial value=6
0. If l as 1=20, it should be FP-Niji d two sets-1 8000/200.

This embodiment has been explained using the feedforward (No. 8 Grofile) shown in FIG. 4(A) as an example.

The present invention is not limited to this example, but any feedforward signal flow profile can be achieved by changing the content of the flow program used.

(f) Effects of the Invention As explained in detail above, according to the magnetic head positioning control method of the present invention, the feedforward signal flow file can be achieved using a digital computer, and the total
By subtracting feeds 7 and 15 for each calculation rifle in the final stage of the seek, the final stage of the velocity flow file becomes gentle and a control system without overshoot can be achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the seek control system of a conventional magnetic head, and FIG. 2 is an explanatory graph of the acceleration and velocity of the magnetic head with respect to the time axis, and (A) is a graph of the feedforward signal 9.
．． CB+ indicates the velocity profile signal. w; Figure 3 is a conventional feedforward @7 generation circuit, Figure 4 is a graph explaining the acceleration and velocity of the magnetic head of the present invention, Figure 5 is a feedforward signal generation circuit of the magnetic head positioning control system of the present invention, FIG. 6 shows the feedforward flow diagram of the ROM. In the figure, 1 is a magnetic disk device, 2 is a magnetic disk,
3 is a magnetic head, 12 is a velocity flow file signal, 19
and 19a indicate feedforward signals. Figure 1 Figure 2 Figure 4 Leap.

Claims (1)

[Claims] In a magnetic head positioning control method in which a magnetic head is positioned at a desired position on a magnetic disk using feedforward control according to a speed profile, the speed profile A magnetic head positioning control method, characterized in that the feedforward control signal is reduced to a certain period in response to the above.