JP2867786B2 - Initial value setting 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 digital controller for controlling the position of a disk drive head, and more particularly to a method for setting initial values of internal variables of the control law.

[0002]

2. Description of the Related Art In general, in a position control device, a transient characteristic at the start of a control operation greatly changes depending on a control operation initial value. Therefore, it is important to set a control operation initial value to an appropriate value. The operation of the disk drive head position control digital controller can be roughly classified into a control mode using a phase compensation filter, a PID controller, or the like, a position control mode for following the track center, a generated target speed trajectory and a head speed. There is a speed control mode for performing a movement seek from one track to another track by proportionally feeding back the difference between the two. In this control system, at the end of the seek operation, the mode must be shifted from the speed control mode to the position control mode, and the control rule must be switched. The initial value of the control calculation of the position control mode control rule is set to an appropriate value. There is a need to. If the initial value is not an appropriate value, the transient characteristics at the end of the seek operation deteriorate, and the time until the position error with respect to the target track becomes sufficiently small, when the target track cannot be followed, or in extreme cases May be unable to control the position.

Therefore, in the conventional initial value setting method, an internal variable is updated by calculating the position control control rule for a sufficiently long time before switching to the position control mode, and an initial value is given at the time of mode switching.

[0004] The above PID is proportional (Propo)
temporal) element, integral (Integral) element,
An abbreviation for Differential element.
A control method using an ID element is generally used in the field of control engineering.

[0005]

In the above-described conventional initial value setting method, an appropriate initial value is given to a control law in the disk drive head position control digital controller by a simple initial value setting mechanism. Performing calculation of a control law not used in the speed control mode while performing the speed control mode has a disadvantage that a calculation load increases and a long calculation time is required.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and reduce the calculation load on a digital controller by calculating an initial value of a primary filter by a linear combination of a position signal value and a velocity signal value. It is therefore an object of the present invention to provide an initial value setting method in which the disk device does not need to perform the operation of the position control mode control rule in the speed control mode, the operation load on the digital controller is reduced, and the operation time is shortened.

[0007]

According to a first aspect of the present invention, there is provided an initial value setting method for a disk drive head position control digital controller in which a control law is expressed in the form of a primary filter. A measuring unit that measures and outputs a value immediately before the start of the control operation of the speed signal, a calculation result obtained by multiplying a position signal value output from the measuring unit by a preset position constant, and a speed signal output from the measuring unit A calculation unit that adds a value and a calculation result obtained by multiplying the value by a preset speed constant, and outputs a new calculation result. This is the initial value of the internal variable. The initial value setting method according to the second aspect of the present invention is the initial value setting method for a disk drive head position control digital controller in which a control law is expressed by a combination of a plurality of primary filters. A measurement unit for measuring and outputting the immediately preceding value, and an operation of multiplying each of the primary filters constituting the control law by a position signal value output from the measurement unit and a preset corresponding position constant. It has an initial value setting mechanism consisting of a calculation unit that adds the result and a calculation result obtained by multiplying a speed signal value output from the measurement unit by a corresponding speed constant set in advance and outputs a new calculation result. And
The output of the initial value setting mechanism is set as the initial value of each internal variable of the plurality of primary filters.

[0008]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of an initial value setting mechanism for realizing an initial value setting method according to an embodiment of the first invention.

In FIG. 1, an initial value setting mechanism for realizing the initial value setting method according to the first embodiment of the present invention includes a measuring unit 11.
And a calculation unit a12, and the measurement unit 11
The position signal 1a and the speed signal 1b are sampled according to the measurement instruction signal 1e, and the position signal value 1c and the speed signal value 1d immediately before the start of the control operation are output. Then, the calculation unit a12 calculates
An initial value 1f is calculated from the position signal value 1c and the speed signal value 1d.

FIG. 2 is a block diagram showing the configuration of an initial value setting mechanism for realizing the initial value setting method according to the second embodiment of the present invention in a case where a control law is represented by a combination of two primary filters.

In FIG. 2, an initial value setting mechanism for realizing the initial value setting method according to the second embodiment of the present invention
And a calculating unit b22, and the measuring unit 21
The position signal 2a and the speed signal 2b are sampled according to the measurement instruction signal 2e, and the position signal value 2c and the speed signal value 2d immediately before the start of the control operation are output. Then, the calculation unit b22 calculates
From the position signal value 2c and the speed signal value 2d, an initial value 2f,
Calculate 2 g. FIG. 3 is a configuration block diagram of a measuring unit of the initial value setting mechanism for realizing the initial value setting method according to the first and second embodiments of the present invention.

In FIG. 3, measuring units 11 and 21 of the initial value setting mechanism for realizing the initial value setting method according to the first and second embodiments of the present invention include a storage circuit 31 and a storage circuit 32.
The storage circuit 31 samples the position signal 3a based on the measurement instruction signal 3e and outputs a position signal value 3c. Then, the storage circuit 32 stores the measurement instruction signal 3e.
Sample the speed signal 3b and output the speed signal value 3d. The speed signal 3b can be generated using an observer mechanism or the like. It can also be generated from a time series of position signals. FIG. 4 is a block diagram showing the configuration of the calculation unit of the initial value setting mechanism for realizing the initial value setting method according to the first embodiment of the present invention.

In FIG. 4, a calculating unit a12 of the initial value setting mechanism for realizing the initial value setting method according to the first embodiment of the present invention.
Comprises a multiplier 41, a storage circuit 42, a multiplier 43, a storage circuit 44, and an adder 45.
Multiplies the position signal value 4a by the position constant 4c stored in the storage circuit 42. The multiplier 43 converts the position signal value 4b into
Multiply by the speed constant 4d stored in the storage circuit 44. Then, the adder 45 calculates the multiplication result of the multiplier 41 and the multiplier 43
And the result of multiplication is added to calculate an initial value 4e. FIG. 5 is a block diagram showing the configuration of the calculation unit when the control law is expressed by two primary filters of the initial value setting mechanism for realizing the initial value setting method according to the second embodiment of the present invention.

In FIG. 5, a calculating unit b22 of the initial value setting mechanism for realizing the initial value setting method according to the second embodiment of the present invention.
Is composed of a multiplier 51, a storage circuit 52, a multiplier 53, a storage circuit 54, a multiplier 55, a storage circuit 56, a multiplier 57, a storage circuit 58, and an adder 59. 5a is multiplied by the first position constant 5c stored in the storage circuit 52. The multiplier 53 converts the position signal value 5b into
The first speed constant 5d stored in the storage circuit 54 is multiplied. The multiplier 55 multiplies the position signal value 5a by the second position constant 5e stored in the storage circuit 56. Multiplier 57
Is the position signal value 5b and the second signal stored in the storage circuit 58.
Is multiplied by the speed constant 5f. The adder 59 adds the multiplication result of the multiplier 51 and the multiplication result of the multiplier 53 to calculate a first initial value 5g. The adder 60 is connected to the multiplier 5
5 and the multiplication result of the multiplier 57 are added, and the second
Is calculated as 5h. Next, a method of calculating the position constant and the velocity constant will be described below. First, consider the case where the control law of the digital controller is represented by a single primary filter. At this time, the control law is represented by the following equation. The filter input u represents a position signal, and the filter output y represents a control signal.

[0016]

From equation (1), the transfer function from the input u to the internal variable x is expressed as follows. x (s) = g (s) u (s) = b / (sa) u (s) (3) Further, an error e between the input u and the internal variable x is defined as follows. e (t) = u (t)-(-a / b) x (t) (4) e (s) = u (s)-(-a / b) x (s) (5) At the time of initial value setting, such as at the end, the head moving speed is controlled to be substantially constant. Therefore, it is assumed that the head moving speed is constant v, and the filter input u which is a position signal is set as follows. u (t) = vt + c (v and c are constants) (6) u (s) = v / s ² (7) The following results are obtained by considering equations 3, 5, and 7. e (s) = u (s) + (a / b) x (s) = v / s (s−a) (8) By applying the final value theorem, equation 9 can be obtained. x (∞) = (− b / a) u (∞) + (− b / a ² ) v (9) Therefore, assuming that the head speed is kept constant for a sufficiently long time, the position constant is expressed as ( -B / a) and the rate constant can be (-b / a ² ). Next, consider the case where the control law of the digital controller is expressed as a combination of two first-order filters. When two filters are connected in parallel, the control law can be expressed by the following equation.

[0018]

At this time, two position constants and two velocity constants for determining the initial values of the internal variables of the two filters are obtained by applying the procedure for a single filter to each of the equations (10) and (11). Formulas can be derived and defined. When two filters are connected in series, the control law can be expressed by the following equation.

[0020]

The position constant and velocity constant for determining the initial values of the internal variables of the first-stage filter can be defined by applying the procedure for a single filter to equation (13).
The input of the second-stage filter is the output y1 of the first-stage filter, and the error f is defined by Expression 18. _{y 1 (s) = [d} 1 + b 1 c 1 / (s-a 1)] u (s) (17) f (t) = u (t) - (- a 1) / (b 1 c 1 - a ₁ d ₁ ) y ₁ (t) (18) At this time, considering equation 7, since the steady speed deviation becomes a constant value, when u changes at speed v, y ₁ becomes speed −
It believed to be changed with _{(b 1 c 1 -a 1 d} 1) v / a 1. Therefore, the u of formula (9) in the procedure for a single filter y _1, v a _{- (b 1 c 1 -a 1} d 1) v /
by replacing a _1, a position constant that determines the initial value of the internal variable of the second stage filter, defines the rate constant. By repeating the above procedure, even when the control law of the digital controller is expressed as a combination of three or more primary filters, the position constant and velocity constant corresponding to each filter are calculated. The above configuration can be realized as circuit hardware or program software of a digital control processor.

In each of the components shown in FIGS.
The components having the same name but different item numbers have the same functions only by changing the item numbers for easier explanation.

[0023]

As described above, according to the initial value setting method of the present invention, the initial value of the primary filter is calculated by a simple operation of the linear combination of the position signal value and the velocity signal value, thereby enabling the disk drive to be used. In this case, there is no need to perform the operation of the position control mode control rule in the speed control mode, so that the operation load on the digital controller can be reduced and the operation time can be shortened.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an initial value setting mechanism for realizing an initial value setting method according to an embodiment of the first invention.

FIG. 2 shows an initial value setting method according to one embodiment of the second invention.
FIG. 10 is a block diagram of a configuration of an initial value setting mechanism that is realized in a case where a control law is represented by a combination of primary filters.

FIG. 3 is a configuration block diagram of a measuring unit of an initial value setting mechanism for realizing the initial value setting method according to the first and second embodiments of the present invention;

FIG. 4 is a configuration block diagram of a calculation unit of an initial value setting mechanism for realizing the initial value setting method according to the embodiment of the first invention.

FIG. 5 is a configuration block diagram of a calculation unit when a control law is expressed by two primary filters of an initial value setting mechanism for realizing the initial value setting method according to the second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 Measurement unit 12 Calculation unit a 1a Position signal 1b Speed signal 1c Position signal value 1d Speed signal value 1e Measurement instruction signal 1f Initial value 21 Measurement unit 22 Calculation unit b 2a Position signal 2b Speed signal 2c Position signal value 2d Speed signal value 2e Measurement instruction signal 2f, 2g Initial value 31, 32 Storage circuit 3a Position signal 3b Speed signal 3c Position signal value 3d Speed signal value 41,43 Multiplier 42,44 Storage circuit 45 Adder 4a Position signal value 4b Speed signal value 4c Position Constant 4d Speed constant 4e Initial value 51, 53, 55, 57 Multiplier 52, 54, 56, 58 Storage circuit 59, 60 Adder 5a Position signal value 5b Speed signal value 5c First position constant 5d First speed constant 5e Second position constant 5f Second speed constant 5g First initial value 5h Second initial value

Claims (2)

(57) [Claims] 1. An initial value setting method for a disk drive head position control digital controller in which a control law is expressed in the form of a first-order filter. And a calculation result obtained by multiplying a position signal value output from the measurement unit by a predetermined position constant, and a calculation result obtained by multiplying a speed signal value output from the measurement unit by a predetermined speed constant. And a calculation unit that outputs a new calculation result. The output of the initial value setting mechanism is used as an initial value of an internal variable of the primary filter. Initial value setting method. 2. A disk drive head position control digital controller initial value setting method in which a control law is expressed by a combination of a plurality of first-order filters, and measures and outputs values of a position signal and a speed signal immediately before a control operation is started. A measurement unit that calculates a result of multiplying a position signal value output from the measurement unit by a corresponding position constant that is set in advance for each of the primary filters constituting the control law; A calculation unit that adds a calculation result obtained by multiplying a speed signal value output from the unit by a corresponding speed constant set in advance, and outputs a new calculation result. An initial value setting method, wherein an output of the value setting mechanism is an initial value of an internal variable of each of the plurality of primary filters.