JPH02183311A - Adjusting method for positioning control off-set of servo circuit - Google Patents

Abstract

PURPOSE:To automatically adjust the circuit off-set of a position control system by measuring the integrated value of a positioning signal in each off-set while the off-set is changed and determining an off-set value, of which the integrated value is made minimum. CONSTITUTION:A main control part 6 changes an off-set adjusted value to be given to a position control part 4 and repeats the move of a fixed distance. Then, the integrated value of a positioning signal is measured at the time of position control in each off-set adjusted value and the off-set adjusted value, of which the integrated value is made minimum, is set as the optimum off-set value. Namely, since the influence of the off-set appears in the waveform of the positioning signal in the positioning signal, the positioning signal is integrated in the position control with changing the off-set value. Then, the off-set value, of which the integrated value is made minimum, is discovered and adjusted. Thus, since the off-set is can be automatically adjusted, the adjustment by man power is eliminated and the adjustment can be realized at low cost without any error.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figs. 7, 8, and 9) Problems to be solved by the invention Means for solving the problems (Fig. 1) ) Functional Examples (a) Explanation of the configuration of one embodiment (FIG. 2, FIG. 3M) (b) Description of operation of one embodiment (FIG. 4, FIG. 5, FIG. 6) (C) Other examples Description of Embodiments Effects of the Invention [Summary] The present invention relates to a position control offset adjustment method for eliminating offset in a position control system in a servo circuit that positions a servo target at a target position by speed control and position control, without requiring human intervention. The purpose of this system is to automatically adjust the circuit offset of the position control system without the need for a servo. It has a position control section that performs position control based on a position error signal, a switching section that switches and connects the servo target to the speed control section or the position control section, and a main control section that switches and controls the switching section. In the servo circuit configured to switch from speed control to position control, the offset adjustment value given to the position control unit is changed to repeatedly move a constant distance f, and the position signal during position control at each offset adjustment value is and a step of setting the offset adjustment value that minimizes the integral value as the optimal offset value.

[Industrial application field]

The present invention relates to a position control offset adjustment method for eliminating offset in a position control system in a servo circuit that positions a servo target at a target position by speed control and position control.

Servo circuits are widely used for track positioning of magnetic heads in magnetic disk drives.

In such a servo circuit, if an offset l- exists in the analog circuit of the position control system, position control cannot be performed smoothly, so an offset adjustment technique is required to remove the offset.

[Conventional technology]

7 and 8 are explanations of the prior art.

In FIG. 7, l is a servo target, which includes a voice coil motor 1a, a servo head 1b moved by the voice coil motor la, and a position signal generation circuit 1c that generates a position signal Ps from a read signal of the servo head Ib. have.

2 is a speed detection circuit, which detects the actual speed Vr from the position signal Ps and a detection current 1c, which will be described later. 3 is a speed error detection circuit, which detects the target speed Vc and the actual speed V, which will be described later.
It generates a speed error Δ■ with r and controls the speed, and these constitute a speed control section.

4 is a position error detection circuit position control section, which generates a position error signal ΔP from the position signal Ps and the detection current IC, and controls the position; 5 is a power amplifier and a switching section, including a changeover switch; and a power amplifier, and connects the speed error detection circuit 3 or the position error detection circuit 4 to the servo target 1 in response to a coarse (speed control)/fine (position control) switching signal.

6 is a main control unit, which is composed of a microprocessor;
It generates a target speed curve Vc corresponding to the amount of movement, monitors the position of the servo target 1 using track crossing pulses to be described later, and generates a switching signal from coarse to fine near the target position.

7 is a control current detection circuit which detects the control current Is of the power amplifier 5 and generates a detection current signal IC;
A track crossing pulse generation circuit generates a track crossing pulse from the position signal Ps and outputs it to the main control section 6.

When the main control unit 6 is given the number of moving tracks (travel amount), it generates a target speed cube Vc according to the number of moving tracks, drives the voice coil motor 1a by speed control, and when it reaches the vicinity of the target position. , the switching unit 5 is switched to the position control side, and the voice coil motor 1a is positionally controlled to position the voice coil motor 1a to a desired track.

As shown in FIG. 8, the position control unit 4 that performs this position control includes a filter 4 that cuts high frequency components of the position signal PsO.
0, an amplifier 41 that amplifies the output of the filter 40, an integration circuit 42 that integrates the output of the filter 40, a differentiation circuit 43 that differentiates the output of the filter 40 and the control current detection signal IC, the amplifier 41, and the integration circuit. 42, a position error generator 44 that generates a position error signal from the output of the differentiation circuit 43, and resistors r1 to r4 for adjusting the offset of the differentiation circuit 43.

Since such a position control system is composed of analog circuits, a circuit offset inevitably occurs.

In particular, the offset of the current feedback system is large, for example, the influence of the offset of the amplifier of the control current detection circuit 7 is large.

FIG. 9 is an explanatory diagram of the prior art.

If there is no circuit offset, as shown in Figure 9 (A), after switching from coarse (speed control) to fine (position control), the position signal Ps immediately converges to 0■, and after switching to fine, the position signal Ps remains constant for a certain period of time. Sealing is completed when the level does not exceed a constant bell (on-track level).

However, if a circuit offset exists, Figure 9(B)
As shown in the figure, after switching to fine mode, the position signal Ps gradually rises to correct the circuit offset, and the shift is completed without reaching a certain level for a certain period of time, but then a peak occurs and the on-track You may exceed your level.

If this exceeds the on-track level, the servo target 1 has been moved beyond the on-track level.

In order to correct this circuit offset, especially the offset of the current feedback system, conventionally the position signal is observed with an oscilloscope while shifting in a certain period is repeated, and the variable resistor r
4 (Figure 8) was adjusted by humans.

[Problem to be solved by the invention]

However, since the adjustments were made by humans, there were problems in that adjustment variations were likely to occur due to individual differences and adjustment variations due to measuring instruments (oscilloscopes), etc., and there was also the problem of cost amplification due to measuring instruments, personnel costs, etc.

Therefore, an object of the present invention is to provide an automatic position control offset adjustment method for a servo circuit that can automatically adjust the circuit offset of a position control system without human intervention.

[Means to solve the problem] FIG. 1 is a diagram showing the principle of the present invention.

As shown in FIG. 1, the present invention includes a speed control unit 2.3 that detects the actual speed of the servo target l and controls the speed based on the speed error with the target speed, and a position that is obtained from the position signal of the servo target l. A position control section 4 that performs position control based on an error signal, a switching section 5 that switches and connects the servo target I to the speed control section 2.3 or the position control section 4, and a main control section 6 that switches and controls the switching section 5. and a servo circuit configured to switch from speed control to position control near the target position,
A step of changing the offset adjustment value given to the position control unit 4, repeating movement over a certain distance, and measuring the integral value of the position signal during position control at each offset adjustment value, and the integral value is the minimum value. and setting the offset adjustment value as the optimum offset value.

[Effect]

Since the influence of offset appears in the waveform of the position signal Ps in position control as described above, the present invention integrates the position signal in position control while changing the offset value, and finds the offset value that minimizes the integral value. This is an attempt to make adjustments.

Since the offset can be automatically adjusted, manual adjustment is not required, and adjustment can be achieved without errors and at low cost.

〔Example〕

(a) Description of the configuration of one embodiment FIG. 2 is a configuration diagram of one embodiment of the present invention, and FIG. 3 is a diagram showing the configuration of the position control section in the configuration of FIG. 2.

In the figures, the same parts as those shown in FIGS. 1, 7, and 9 are indicated by the same symbols.

Reference numeral 9 denotes an integrating section, which includes a switch 90 that is turned on by the main control section (hereinafter referred to as MPU) 6 and allows the position signal Ps to pass through, an absolute value circuit 91 that converts the position signal Ps from the switch 90 into an absolute value, and an absolute value circuit 91 that converts the position signal Ps from the switch 90 into an absolute value. An integrating circuit 92 integrates the output of the circuit 91, and an analog/digital converter (ADC) converts the analog output of the integrating circuit 92 into a digital value.
)93.

62 is an offset register for storing the offset value; 63 is an integration number register for storing the number of integrations; 64 is a work register for storing various measured values FWD, RVS, T1 . It stores Tz, T3, and A.

In FIG. 3, 45 is a digital/analog converter (referred to as DAC), which is connected to the resistor "?"
The digital offset value from 6 is converted into 4 analog offset values, and the offset of the differentiating circuit 43 is set.

(b) Description of operation of one embodiment FIG. 4 is a flowchart of adjustment processing according to an embodiment of the present invention, FIG. 5 is a flowchart of forward/reverse offset adjustment value determination processing of FIG. 4, and FIG. FIG. 6 is a flowchart of the integral sampling process shown in FIG. 5;

5 is a subroutine of the flow shown in FIG. 4, and FIG. 6 is a subroutine of the flow shown in FIG.

First, the entire adjustment process will be explained with reference to FIG.

(2) Before starting adjustment, the MPU 6 resets various registers.

■Next, the MPU 6 executes a subroutine to be described later in FIG. 5, determines the offset adjustment value in the forward direction, and stores the determined offset adjustment value I in the register 6.
4 "FWD'".

(2) The M P tJ 6 further executes a subroutine to be described later in FIG.

■ Next, the MPU 6 selects 'FWS' and 'FWS' in the register 64.
RV S '' is calculated, and the average value is set in the register 62 as "°L" and output.

Next, the offset adjustment value determination process will be explained with reference to FIG.

■ First, the MPU 6 sets the number of integrations I in the register 63 to “
3” cents. That is, the integration is performed three times.

(2) The MPU 6 sets an offset adjustment value in the register 62 and outputs "L" to the DAC 45 of the position control section 4.

Then, the MPU 6 executes an integral sampling subroutine, which will be described later in FIG.

At this time, this routine is repeated multiple times and the integral values are averaged.

Next, the MPU 6 sets 1 of the register 62 to (L x)
The number of integrations I in the register 63 is updated to (]■).

The OMPU 6 checks whether the number of integrations 1 in the register 63 is "0", and if it is not "0", returns to step (2).

(2) On the other hand, if I=0, the three integral operations have been completed and the integral values T1, 'r2, and T3 have been obtained, and the current gain is (+-+3X).

First, the MPU 6 calculates the first integral (aTl and the second integral 4).
Compare with MTq.

If T1≧T2, that is, TI<T2, Offsen I-
Since the minimum value cannot be obtained due to the monotonous increase with respect to the increasing change of L, we can calculate L by (L-4X), that is, L =
Since L+3X, reduce to (L-X) and return to step ①.

■ On the other hand, if T1 is 1゛2, the second integral value T2 and 3
The second integral value T3 is compared.

``3≧1゛If not 2, that is, l' 3 <i'' 2, then offset) Since the minimum value cannot be obtained due to a monotonous decrease in response to an increasing change in L, the offset L can be set as (L-2X),
That is, since L=(L+3X), increase it to (L+X) and return to step (2).

■ If T3≧T2, then the relationship T1≧T2≦T3 holds true, and T2 is the minimum value. seek,
The offset determination value in the forward direction is stored in the register 64 as "FWD", and the process returns.

Incidentally, the offset determination value "RVS" in the reverse direction is obtained in the same manner by performing the integration->non-pulling in the reverse direction in step (3).

Next, the integral sampling process will be explained with reference to FIG.

(i) MPLJ6 starts forward seek of the scheduled difference amount.

(ii) The MPU 6 determines whether the speed control has ended, and when the speed control ends, issues an integration start signal, turns on the switch 90, and operates the integration circuit 92.

Then, the integration circuit 92 starts integrating the position signal Ps from the end of the speed control, as shown in FIG. 1(B).

(iii) In this way, after the speed control is switched to the position control, the on-track signal continues for a certain period of time, so that it is determined that the shearing has ended.

After a further scheduled time, the integration start signal is turned off, the switch 90 is turned off, the integration circuit 92 is made inactive, and the integration is completed.

Therefore, the integration period becomes as shown in FIG. 1(B).

(iv) After the integration period ends, the MPU 6 samples the integral value from the ΔDC 93 and stores "A" in the register 64.
Store as .

Then, rehearse and seek for the scheduled amount of time.

The above flow is an integral sampling process in the forward direction, but in the reverse direction, forward seek is changed to reverse seek in step (1), and step (IV
), just change rehearsal seek to forward seek.
The rest is the same.

In this way, there may be a difference in the offset between the forward direction and the reverse direction, so as shown in FIG. 4, offset adjustment values in both directions are determined and the average value is used as the automatic offset adjustment value.

Furthermore, since the offset value that minimizes the integral value of the position signal is determined, an appropriate offset adjustment value can be changed.

(C) Description of other embodiments In the embodiments described above, the servo target is a magnetic disk device, but it may be another device, or the MPU 6 may perform the integration operation without providing an integration section. .

Although the present invention has been described above using examples, the present invention can be modified in various ways according to the gist of the present invention, and these are not excluded from the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, the integral value of the position signal Ps at each offset is measured while changing the offset, and the offset value with the minimum integral value is determined, so that the position control system The effect is that the circuit offset can be automatically adjusted, no adjustment error occurs, the adjustment cost can be reduced, and furthermore, adjustment in the field can be easily performed.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is a block diagram of the position control section in the configuration of Fig. 2, and Fig. 4 is an adjustment diagram of an embodiment of the present invention. Processing flow diagram, FIG. 5 is a flowchart of offset adjustment value determination processing in FIG. 4, FIG. 6 is a flowchart of integral sampling processing in FIG. 5, and FIGS. 7, 8, and 9 are explanations of prior art. It is a diagram. In the figure, 1-servo target, 2-speed detection circuit, 3-speed error detection circuit, 4-position error detection circuit, 5-switching section, 6-main control section.

Claims (1)

[Claims] A speed control unit (2, 3) that detects the actual speed of the servo target (1) and controls the speed based on the speed error with the target speed; and a position obtained from the position signal of the servo target (1). A position control unit (4) that performs position control based on an error signal, and a position control unit (4) that controls the position of the servo target (
1) to the speed control part (2, 3) or the position control part (4), and a main control part (6) to switch and control the switching part (5). , In a servo circuit configured to switch from speed control to position control near the target position, the position control section (4)
A step of repeatedly moving a certain distance by changing the offset adjustment value given to the offset adjustment value, and measuring the integral value of the position signal during position control at each offset adjustment value, and determining the offset adjustment value that minimizes the integral value as the optimal offset. 1. A position control offset adjustment method for a servo circuit, the method comprising: setting the offset as a value.