JPH0659742A - Magnetic disk controller - Google Patents

Abstract

(57) [Abstract] [Purpose] In a magnetic disk head positioning control device, a conventional digital arithmetic unit obtains necessary data by referring to a table. In the present invention, it is possible to refer to highly accurate data with a small memory capacity. [Structure] A coordinate value calculation unit is provided. The digital operation unit
Instead of storing a table, data for controlling the shapes of several functions is stored. [Effect] The digital arithmetic unit only needs to have a memory having a small capacity as compared with storing a table, and can obtain highly accurate data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk head positioning control device.

[0002]

2. Description of the Related Art A conventional head positioning control apparatus includes an AD converter 201, a digital operation unit 202, a DA converter 203, and a VCM driver 20, as shown in FIG.
4, position signal demodulation circuit 205 and table 206. The digital arithmetic unit 202 performs arithmetic while referring to the table 206 as necessary, and moves the head to a target track and positions it (seek). Table 2
A target speed curve is stored in 06, for example. FIG. 9 is a schematic diagram of a target speed curve, showing the target speed of the head with respect to the number of remaining tracks, which is the difference between the target track and the current position track. In order to store the target speed curve in a table, some coordinate values of the target speed curve are arranged as shown in FIG. In the table of FIG. 10, if the digital operation unit 202 knows by what rule the x coordinates are arranged, only the y coordinate needs to be stored. The actual table has 25
About 6 coordinate values are stored. Further, in addition to the target speed table described above, a plurality of tables such as an acceleration table are often provided.

A related device of this type is disclosed in Japanese Patent Laid-Open No. 3-233609. In this example,
It stores a table showing the relationship between the moving distance (seek distance) of the head and the target moving time (target seek time) and the table showing the relationship between the normalized time and the normalized position.

[0004]

Recently, in order to increase the accuracy and speed of head positioning control, it is necessary to have a plurality of tables with more detailed information. However, since the memory attached to the high-speed digital operation unit is usually high-speed and has a small capacity, it is not possible to store all the tables in the memory of the digital operation unit. Therefore, if all the tables are to be stored in the form of the table, the memory of the digital arithmetic unit must have a large capacity.

The above-mentioned conventional technique has a problem that the storage of the table is not taken into consideration and the memory of the digital arithmetic unit must be large in capacity.

It is an object of the present invention to be able to store the values of a plurality of tables in a small capacity memory.

The values obtained from the table are discontinuous. If you want an intermediate value between two coordinate values in the table, substituting the existing value in the table will reduce the accuracy. Alternatively, even if the required value is obtained by interpolating from the values existing in the table, it takes extra processing time and the accuracy is not sufficient. The above-mentioned related art has a problem in that the discontinuity of the data in the table is not taken into consideration and the accuracy of the data becomes low.

An object of the present invention is to make it possible to refer to highly accurate data.

[0009]

In order to achieve the above-mentioned object, a continuous function y = f (x) for the discontinuous values in the table is used.
A means for calculating the variable y is provided by inputting a constant x for controlling the shape of the function and the variable x.

[0010]

Since the means for calculating the variable y is provided when the constant for controlling the shape of the function and the variable x are input, the digital arithmetic unit does not have a table, but has several constants for controlling the shape of the function. Good. Also, since it is expressed as a function,
Highly accurate because it can represent continuous values. Also, by changing the constants that control the shape of the function, functions of various shapes can be expressed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

First, the first embodiment will be described.

FIG. 1 is a block diagram of a head positioning device for a magnetic disk. Reference numeral 101 is an AD converter, 102 is a digital operation unit, 103 is a DA converter, 104 is a VCM driver, and 105 is a position signal demodulation circuit.

Reference numeral 106 denotes a coordinate value calculation unit which is the center of the present invention. Conventionally, the digital calculation unit 102 refers to a required value using a table, but in the present embodiment, the coordinate value calculation unit 106 is used to refer to a required value. The coordinate value calculation unit 106 has a function of calculating the coordinates of the quadratic Bezier curve. The quadratic Bezier curve represents a curve with three control points. Curves with various curvatures can be expressed by moving the control points.

FIG. 3 shows a curve control point (x1, y1) 30.
1, curve control point (x2, y2) 302, curve control point (x
3, y3) 303 is an example in which the target speed curve is represented by three points. The x-axis is the number of remaining tracks from the current position track to the target track, and the y-axis is the target speed of the head with respect to the number of remaining tracks. The curve control point 301 represents the start point of the curve, the curve control point 302 controls the bending degree of the curve,
The curve control point 303 represents the end point of the curve. The digital calculation unit 102 uses the curve control point 3 as the target speed curve.
The coordinates 01, 302, 303 are stored. And
For example, when it is desired to refer to the target speed corresponding to the number of remaining tracks a304, as shown in FIG.
6, the x coordinate a304 and the three curve control points 301, 30
Enter the coordinates of 2,303. Then, the coordinate value calculation unit 1
06 calculates the y-coordinate b305 of the point on the curve corresponding to the x-coordinate a304 and outputs the y-coordinate b305. The digital arithmetic unit 102 calculates the output y-coordinate b305 as
Use it as a target speed.

Next, the processing of the coordinate value calculation unit 106 will be described with reference to FIG. The quadratic Bezier curve is expressed by the following equation using three curve control points (x1, y1) (x2, y2) (x3, y3) and the parameter t.

[0017]

[Equation 1]

[0018]

[Equation 2]

The coordinate value calculation unit 106 calculates the x coordinate a and three curve control points (x1, y1) (x2, y2) (x3, y.
3) is input, a solution t of a = f (t) obtained by substituting a into Equation 1 is first obtained in block 501, and the value of the medium variable t is output. Next, in block 502, t is substituted into Equation 2 to calculate the y coordinate. The value of this y coordinate is output.

When the digital arithmetic unit 106 needs a plurality of velocity curves which differ depending on the seek distance, or when other functions such as target acceleration are necessary, the curve control points corresponding to these functions should be stored. Good.

Further, in FIG. 3, when the x-coordinate c306 of a point protruding from the curve control point is input to the coordinate value calculation section 106, the maximum value of the y-coordinates of the curve control point is output. Should be set.

Further, when a function having a more complicated shape is required, the degree of the Bezier curve is increased, the coordinate value calculation unit 106 has a function of calculating the coordinates of the Bezier curve of that degree, and the digital operation unit 102 has the function. It suffices to have a control point corresponding to the order.

Next, the second embodiment will be described. In the second embodiment, the coordinates are calculated using a cubic spline curve. The cubic spline curve is a curve in which four control points represent a curve, and the curve lies on the control points.

FIG. 6 is a diagram showing the target velocity curve of the head, with the x-axis representing time and the y-axis representing the target velocity. There are four control points 601 to 604 on the curve, and the curve is placed on the control points. In addition, the curve control point x
Expansion ratio Px605 in the direction and expansion ratio Py606 in the y direction
That controls the expansion and contraction of the curve. The expansion / contraction rate of the curve control point may be used when it is desired to expand / contract the velocity curve according to the seek distance.

When the digital arithmetic unit 102 wants to refer to the target speed, as shown in FIG. 7, the x coordinate a 607, the four coordinate values of the curve control points 601, 602, 603 and 604, and the x direction of the curve control point. The expansion / contraction ratio Px605 and the expansion / contraction ratio Py606 in the y direction are input to the digital arithmetic unit 102. Then, the coordinate value calculation unit 106 calculates and outputs the y-coordinate b. The digital calculation unit 102 obtains this y coordinate b as the target speed.

Next, the processing of the coordinate value calculation unit 106 will be described with reference to FIG. In block 801, the x-direction expansion / contraction ratio Px is assigned to the x-coordinates x1, x2, x3, and x4 of all curve control points.
Multiplying the y-coordinates y1, y2, y3, y4 by the y-direction expansion / contraction ratio Py, x1 ′, x2 ′, x3 ′, x4 ′, y1 ′, y
2 ', y3', y4 'are calculated, and the control points of the stretched curve are obtained. Next, in block 802, the coordinates on the spline curve represented by the curve control points obtained in block 801 are calculated. Here, the coordinate value of the spline curve is calculated using Lagrange interpolation. Other methods may be used. The Lagrange interpolation formula is as follows.

[0027]

[Equation 3]

The y-coordinate b608 is calculated using the equation (3). The coordinate value calculation unit 106 outputs this y coordinate b608, and the digital calculation unit 102 obtains the target speed.

Although the quadratic Bezier curve is used in the first embodiment and the cubic spline curve is used in the second embodiment, other functions may be used. Further, the calculation of the function value does not have to be the method shown in the embodiment, and the curve approximation may be performed to increase the processing speed.

In the present embodiment, the function is on the quadratic plane, but it may be a function of cubic space or more.

The coordinate value calculation unit 106 may be configured by hardware or software.

Next, a third embodiment will be described with reference to FIG.

FIG. 11 is a block diagram. New to the above-described embodiment is 117 table memory. In the above-described embodiment, the digital arithmetic unit 102 is
When there is a value to be referred during seek, the coordinate value calculation unit 10
6 had to calculate the coordinate values of the function. In this embodiment, the coordinate value of the function is calculated in advance and the table memory 11 is used.
The conventional table is created in 7.

Before the seek, the digital arithmetic unit 112
The control point of the function corresponding to the table required for the seek to be performed is passed to the coordinate value calculation unit 116. The coordinate value calculation unit 116 calculates some coordinate values of the function and creates a conventional table as shown in FIG. 10 in the table memory 117. After the seek preprocessing such as the calculation of the seek distance and the initialization of the register is completed, the digital arithmetic unit 112 refers to the table created in the table memory 117 as needed to perform the seek.

In the third embodiment, the digital arithmetic unit 11
Since the coordinate value calculation unit 116 calculates the coordinate value of the function during the preprocessing of the second seek, the coordinate value calculation time required during the seek in the above-described embodiment can be shortened. Further, since the table memory 117 is rewritten and used for each seek, it suffices if the table has a memory capacity necessary for one seek.

[0036]

According to the present invention, since the digital arithmetic unit does not have to have a table and only needs to have several pieces of data for controlling the shape of the function, the capacity of the memory to be stored can be small. In addition, since functions of various shapes can be expressed by changing the values of several data that control the shape of the function, it is not necessary to have a plurality of means for calculating coordinate values like a table. For example, to have three 256-word tables requires a memory capacity of 768 words, but according to the present invention, when a quadratic Bezier curve is used, the x-coordinate and y-coordinate of three curve control points are used. Since it is sufficient to store, 6-word memory is enough.

Further, when the data is stored in the form of a table, since the data in the table is discontinuous, an accurate value between the data could not be obtained. Since data is represented as a function, highly accurate data can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a configuration diagram of a conventional example.

FIG. 3 is an explanatory diagram of the first embodiment.

FIG. 4 is an explanatory diagram of the first embodiment.

FIG. 5 is a diagram showing processing of the first embodiment.

FIG. 6 is an explanatory diagram of a second embodiment.

FIG. 7 is an explanatory diagram of the second embodiment.

FIG. 8 is a diagram showing a process of a second embodiment.

FIG. 9 is an explanatory diagram of a conventional example.

FIG. 10 is a diagram showing a table of a conventional example.

FIG. 11 is a configuration diagram of a third embodiment.

[Explanation of symbols]

101 ... AD converter, 102 ... Digital arithmetic unit,
103 ... DA converter, 104 ... VCM driver, 1
05 ... Position signal demodulation circuit, 106 ... Coordinate value calculation unit, 30
1 ... Curve control point (x1, y1), 302 ... Curve control point (x2, y2), 303 ... Curve control point (x3, y3),
304 ... x coordinate a, 305 ... y coordinate b, 306 ... x coordinate c.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location G11B 21/08 H 8425-5D (72) Inventor Tsuyoshi Yoshioka 292 Yoshida-cho, Totsuka-ku, Yokohama-shi Stock Hitachi, Ltd. Microelectronics equipment development laboratory

Claims (3)

[Claims] 1. A magnetic disk head positioning control device including a digital arithmetic unit, wherein a constant and a value of a variable x for controlling the shape of a curve or a straight line of a function y = f (x) are input to the digital arithmetic unit. A magnetic disk controller comprising a calculator for outputting the value of the variable y to a digital calculator. 2. A magnetic disk head positioning control apparatus according to claim 1, wherein the digital arithmetic unit has a plurality of constants capable of controlling the shape of the curve or straight line of the function y = f (x). Magnetic disk controller. 3. In a magnetic disk head positioning control device, a calculation unit for outputting a value of a variable y from a constant and a value of the variable x capable of controlling the shape of a curve or a straight line of a function y = f (x), A magnetic disk controller characterized by creating a table in which the values of the variable y corresponding to the values of the variable x are arranged.