JPH04112205A - Positioning controller - Google Patents

Abstract

PURPOSE:To make it possible to control positioning of a part to be controlled with a high precision without an influence of external oscillation regardless of application of oscillation dependent upon temperature to a system by a control part by constituting a controller of the part to be controlled, a driving part, a position detecting part, the control part, first to third correcting means, and a model. CONSTITUTION:When oscillation is applied to the system, a first correcting means 5 estimates the position of a control part 1 to be controlled by a model 8, where this oscillation is taken into consideration, to correct the control of a control part 4. When the temperature of the system is changed, a second correcting means 6 corrects the model 8 and the correcting means 5 corrects the control of the control part 4. At the time of controlling the control part 4 at intervals of a prescribed time, a third correcting means 7 uses the difference between the position of the part 1 measured by a position measuring part 3 and the estimated position of the part 1 estimated by the correcting means 5 to successively correct the model 8. Thus, the model 8 corrected by the correcting means 7 approximates the actual system, and the correcting means accurately estimates the position of the part 1 to be controlled in a short time, and the control of the control part 4 is corrected.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a head positioning control device in a disk drive, and aims to estimate the vibration of a casing based on the temperature characteristics of a vibration isolating member to achieve highly accurate positioning control. Department and
The control unit includes a drive unit that moves and positions the controlled unit, a position measurement unit that measures the position of the controlled unit, and a control unit that controls the drive unit, and includes at least the controlled unit and the drive unit. a first correction means for modeling the vibration of a system including a part, estimating the position of the controlled part using the model, and correcting control of the control part; a second correction means for correcting, the estimated position of the controlled part estimated by the first correction means based on the model corrected by the second correction means, and the controlled part measured by the position measuring section; and a third correction means for sequentially correcting the model using the difference between the position of the model and the position of the model.

[Industrial application field]

The present invention relates to a head positioning control device in a disk device.

With the recent demands for higher density magnetic disks and optical disks and higher speed actuators equipped with heads, highly accurate head positioning is required.

In a disk device in which a head and a disk are housed in a housing, if the housing vibrates due to external vibrations, this may cause off-positioning. Therefore, there is a need for a positioning control device that can perform highly accurate positioning control even if the housing vibrates.

[Conventional technology]

In a disk device in which a head and a disk are sealed within a housing, temperature changes within the housing can be a major cause of head off-track. For this reason, head positioning control devices have been proposed that compensate for disk expansion and contraction due to temperature changes and off-track caused by thermal eccentricity. Further, in order to prevent vibration of the housing, the housing is sealed with a vibration isolating member interposed therebetween. The applicant has also invented a positioning control device that prevents the influence of resonance on the casing of a vibration isolating member due to external vibrations (Japanese Patent Application No. 2-28198).

[Invention or problem to be solved]

However, in the past, few concrete measures have been taken to prevent the deterioration of the vibration-isolating properties due to temperature changes in the vibration-isolating member and the changes in the vibration-isolating properties due to temperature changes in the resonant system composed of the vibration-isolating member and the casing. It wasn't. In other words, strong anti-vibration members were used to prevent vibrations of the casing due to temperature changes, and features were added to the anti-vibration structure (Japanese Patent Laid-Open No. 1-286192
). Therefore, when the characteristics of the vibration isolating member deteriorate due to temperature changes, the casing vibrates, which adversely affects head positioning control.

On the other hand, when attempting to solve this problem using the above-mentioned Japanese Patent Application No. 2-28198, there was a problem in that access time was too long.

Therefore, the following means was provided for the purpose of estimating the vibration of the casing based on the temperature characteristics of the vibration isolating member and achieving highly accurate positioning control.

[Means to solve the problem]

In view of the above problems, the positioning device of the present invention is
and a driving section 2 that moves and positions the controlled section l, a position measuring section 3 that measures the position of the controlled section l, and a control section 4 that controls the driving section 2, A first correction means 5 that models the vibration of a system including at least the controlled section 1 and the drive section 2, estimates the position of the controlled section 1 using the model 8, and corrects the control of the control section 4. and a second correction means 6 that corrects the model 8 when the temperature of the system changes, and the first correction means 5 estimated by the model 8 corrected by the second correction means 6. The third correction means 7 sequentially corrects the model 8 using the difference between the estimated position of the controlled part 1 and the position of the controlled part 1 measured by the position measuring part 3.

[Effect]

When vibration is applied to the system, the first correction means 5 estimates the position of the controlled part l using a model 8 that takes into account the vibration,
The control of the control unit 4 is corrected. On the other hand, if such vibration is temperature dependent and the temperature of the system changes, the second correction means corrects the model 8, and the first correction means 5 corrects the control of the control section 4.

Furthermore, when controlling the control section 4 at predetermined time intervals, it is not possible to measure the temperature of the system that changes within that period, and an error occurs in the estimated position of the controlled section l by the model 8. To deal with this, the third correction means or the difference between the position of the controlled part l measured by the position measuring section 3 and the estimated position of the controlled part l estimated by the first correction means 5 can be used. , model 8 is successively modified.

As a result, the model 8 corrected by the third correction means
approaches the actual system, and the first correction means 5
The position of can be estimated accurately in a short time, and the control of the control unit 4 can be corrected.

〔Example〕

The principle of the positioning control device according to the present invention will be explained below with reference to FIG.

The control means signal generator 31, which is a control means, controls the control object 3.
2 and a control object model 33 which is a calculation means.
Send. Here, the control means signal generator 31 controls the positioning of the controlled object 32.

Furthermore, the controlled object model 33 is a model of the same device as the controlled object 32. A feature of the present invention is that the position of the controlled object 32 is estimated using the controlled object model 33 to perform accurate positioning. When there is no external vibration, the controlled object model 33 is positioned in exactly the same way as the controlled object 32 by the control signal i from the control means signal generator 31, so that the accurate position of the controlled object 32 can be estimated. Therefore, the control signal i allows highly accurate positioning of the controlled object 32.

However, when the external vibration reaches the controlled object 32, the control signal i from the control means signal generator 31 does not accurately match the controlled object 3.
Positioning 2 becomes difficult. Therefore, the controlled object model 3
No. 3 analyzes the motion of the controlled object 32 under steady vibration, and makes it possible to accurately estimate the position of the controlled object 32 even under the vibration. Then, the controlled object model 33 compares and subtracts the estimated position X from the actual position x1 of the controlled object 32, and further corrects it so that Xt (=X+Xt) becomes 0. The position information X of the controlled object model 33 obtained in this way is fed back to the control means signal generator 31, and an appropriate control signal i is transmitted again to the controlled object 32 and the controlled object model 33. Therefore, even under steady vibration, the control signal i can position the controlled object 32 with high precision. Note that the control signal i is determined by the position information X of the directly controlled object 32.
Since correcting this would require too much access time for positioning, such a method is not adopted.

However, in many magnetic disk devices, for example, the disk, head, etc. are sealed inside a housing, and the housing is supported via a vibration isolating member made of rubber or the like. and,
Since the anti-vibration properties of rubber change depending on the temperature, anti-vibration control may not work effectively due to temperature changes. In such a case, the external vibration becomes an unsteady vibration that depends on the temperature.
In the above method, it is difficult to accurately position the head across the three control objects using the control signal i. Therefore, a characteristic corrector 34, which is a correction means, is connected to the controlled object model 33,
It was decided to correct the characteristics of the controlled object model 33 due to temperature changes. As a result, the temperature-corrected estimated position a X 2 of the controlled object model 33 is changed from the actual position
It is possible to get closer to 1. And characteristic corrector 34
The model 33 of the controlled object corrected by is further corrected to x3 (=x+X2) or 0 as described above, and the control signal i of the control means signal generator 31 is corrected.

Note that the estimated position X2 is the actual position X of the controlled object 32,
Therefore, even if the characteristic corrector 34 is removed, the signal fed back to the control means signal generator 31 is the same. However, this method has not been adopted because it takes too much time for positioning access.

Hereinafter, a detailed description will be given with reference to the specific configuration of the disk device shown in FIG. FIG. 3 is a control system diagram of the disk device of the present invention. The disk device 27 has a disk 11 and a head 13 .
14 in a housing (not shown), and the housing is supported by a vibration isolating member (not shown) such as vibration isolating rubber. In this embodiment, a servo surface servo method is used for head positioning servo, and 13 is a servo head and 14 is a data head, but the present invention is not limited to only the servo surface servo method. The controller 25 is a servo system control circuit 2
2, a read/write control circuit 23 that controls a data head that performs recording or reproduction processing on the disk 11, and a motor control circuit 20 that controls the rotation speed of the spindle motor 12 that rotates the disk 11. The interface 26 sends and receives data to and from a host computer and the like.

Positioning control, which is a feature of the present invention, is performed by the microprocessor (MPU) of the servo system control circuit 22 in this embodiment.
It will be held on the 21st. That is, the control signal oscillator 31 in FIG. 1 is the MPU 21. MPU21 is D/A converter 2
A drive current applied to the drive coil in the actuator 15 is applied to the drive coil in the actuator 15 through the amplifier 17 and the amplifier 17. Actuator 15
This drive current causes the heads 13 and 14 to rotate in the radial direction of the disk 11 and position them on a predetermined track. Therefore, in this embodiment, the controlled object 32 in FIG. 1 is the head 13 and 14 at the tip of the actuator.
It is. On the other hand, the position information of the servo head 13 is transmitted to the amplifier 1.
After amplification in step 6, the signal is demodulated in servo demodulator 18, and transmitted to MPU 21 via A/D converter 19. This allows the MPU 21 to recognize the current positions of the heads 13 and 14.

The system constituted by the casing and the vibration isolating member has a predetermined resonant frequency. The controlled object model 33, which is one of the features of the present invention, includes the resonance system of the casing and the actuator 1
The position and speed of 5, the amount of movement and speed of the housing, etc. are estimated. The controlled object model 33 is created as a program in the MPU 21. However, the controlled object model 33 does not need to be programmed as in this embodiment. Positioning control under steady vibration using this model will be explained.

The position of the heads 13 and 14 due to the movement of the actuator 15 is X, the speed of the heads 13 and 14 is v1, the mass of the actuator 15 is m1, when the actuator is driven with a current U, the Laplace operator is S, and the force constant is BI! Then, S X=V ~ (1)s
v = u - (2). Here, the housing receives a reaction force due to the movement of the actuator 15. The resonant angular frequency of the system of the vibration isolation member and the casing is ω. When the vibration of the housing is considered as a second-order resonance system, the damping constant ζ gives the following response. Note that M is the mass of the entire casing including the mass m of the actuator 15. The amount of movement of the housing at this time is Xo, and the speed of movement is VD! , if the magnitude of the external force acting on the casing is f, then S Xow=Vnt --(4) SVot
= (Lull 2Xot 2ζω6VDg-. From this, the off-track amount y is y = x +
x ot −(6).

Assuming that the magnitude f of the external force acting on the casing is constant over time, the following equation is satisfied.

s f = 0 - (7) If the disturbance f is assumed to be constant over time, or if the disturbance vibration has a sufficiently long period for the sampling time to acquire the servo signal, the magnitude of the disturbance will change within a few sampling times. can be considered to be almost constant, so it can be estimated even for low-frequency disturbance vibrations.

The MPU 21 estimates the numerical value of each variable using the above formula. When estimating, take the difference between the actually measured position and the estimated position calculated using the above formula, and calculate the estimated values of position, velocity, external force, etc. according to the size of the difference between the measured position and the estimated position. Each variable value is corrected by correction.

The moving distance and speed of the actuator and the housing for each sampling time are determined, and the acceleration α of the housing is calculated as follows.

By multiplying this acceleration by an appropriate coefficient and adding it to the current output to the normal actuator, the head can be operated to follow the vibration of the housing.

FIG. 4 is an example of the controlled object model 33 of FIG. 2 in which the actuator 15 is a second-order integral system and the vibration of the casing is a second-order resonance system. In the figure, the actuator 5 has an acceleration α of (Bf-i)/m, a velocity V of α/S, and a position X of V/S based on the drive current i. In addition, the acceleration α of the housing is as shown in equation (8), and the velocity V is (IDE/
S s position Xot is VD! /s. Then, since the off-track amount y is determined from equation (6), the MPU 25 sends a drive signal to the actuator 15 so that y becomes 0.

Next, a mechanism for temperature-correcting the controlled object model 33, which is a feature of the present invention, will be explained. Temperature correction of the controlled object model 33 is performed by the characteristic corrector 34 in FIG. 2, or in this embodiment, the characteristic corrector 34 is also performed by the MPU 21 in FIG.
It is. In FIG. 3, the temperatures of the heads 13 and 14 are determined by a temperature sensor 28 provided inside or outside the disk device, and a temperature measurement circuit 29 that calculates the temperatures of the heads 13 and 14 from the values detected by the temperature sensor 28. It will be done.

The MPU 21 connects the heads 13 and 14 from the temperature measurement circuit 29.
However, such a temperature measurement circuit 29 does not need to be provided in the disk device. Also, without using the temperature sensor 28 and temperature measurement circuit 29, M
You may notify temperature information to PU21. A control method using temperature correction will be explained with reference to FIG.

FIG. 5 is a flowchart of positioning control using the control constant correction method of the present invention. First, step 501 determines whether there is a temperature change. That is, the temperatures of the heads 13 and 14 are measured by the temperature sensor 28 and the temperature measurement circuit 29, and the MPU 21 is notified. If there is a temperature change, step 502 changes the control constants. Here, the control constant specifically represents the track interval, force constant, resistance value of VCM, etc. These serve as indicators for determining the drive current output in step 507, which will be described later. Note that if there is no temperature change, the control constant is not changed, and the correction current and drive current are calculated based on the previous control constant.

Next, in step 503, the positions of the heads 13 and 14 at time Tk (sampling time 1A) are estimated. Next, step 50
4 is determined to be time Tk. This control employs a feedback control method that performs continuous control at fixed time intervals. Therefore, it is determined whether a predetermined time interval has been reached. If it is determined that time Tk has passed,
Step 505 detects the current position of the servo head 13.

This is to calculate the drive current for positioning the head to the target position. The position information of the servo head 13 is MP
U21 will be notified.

Based on the result of step 505, step 509 outputs a driving current through steps 506, 507, and 508. Step 506 calculates the control current. The control current is a current that is passed through the drive coil in order to move the servo head 13 from the current position to the target position without considering the influence of vibration. Step 507 estimates the vibration of the housing when the temperature changes. As mentioned above, the current positions of the heads 13 and 14, which are the control targets, are compared with the positions estimated by the control target model.
The acceleration of the casing is determined by the difference, and the estimated position by the controlled object model is corrected by the measured current position in order to obtain the next estimated position. Step 508 then calculates a correction current that cancels out the effects of vibration.

In contrast, step 507 calculates a correction current.

The correction current is closely related to the control constant of step 502.

Step 509 outputs a drive current based on the control current value and the correction current value. The drive current is a current flowing through the drive coil of the actuator 15 that rotates the heads 13 and 14. This allows the MPU 21 to position the heads 13 and 14 with high precision even if temperature-dependent vibrations are applied to the housing.

Note that since this control is feedback control, the process 508 is counted.

After completing the positioning of heads 13 and 14, the lead
The write circuit 23 performs recording or reproduction processing on the disc 11 . In the write mode, data applied from the host device to the controller 25 via the interface 26 is applied to the data head l4' by the read/write circuit 23 and recorded on a predetermined track of the disk 11.

In the read mode, data read by the data head 14 is transferred from the read/write circuit 23 to the host device via the controller 25 and interface 26.

Although the above-mentioned embodiment mainly describes a magnetic disk device, it can also be applied to other disk devices such as an optical disk device.

We also provide various types of high-precision positioning control, such as positioning the head of printer equipment, positioning of XY stages in manufacturing equipment such as semiconductor integrated circuits, positioning of tools, etc. of numerical control (NC) machine tools, and positioning of robot arms, etc. Applicable to

〔Effect of the invention〕

As described above, according to the present invention, even if temperature-dependent vibrations are applied to the system, the control section 4 can control the positioning of the controlled section 1 with high precision so as not to be affected by external vibrations.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of the present invention, Fig. 2 is a system diagram of a positioning control device according to the invention, Fig. 3 is a control system diagram of a disk device, and Fig. 4 is a diagram showing an example of a controlled object model of the present invention. , FIG. 5 is a flowchart of positioning control using the control constant correction method of the present invention. In the figure, 1 is a controlled part, 2 is a drive part, 3 is a position detection part, 4 is a control part, 5 is a first correction means, 6 is a second correction means, 7 is a third correction means, 8 is the model, l is the disk, 2 is the spindle motor, 3 is the servo head, 4 is the data head, 5 is the actuator, 617 is the amplifier, 8 is the servo demodulator, 9 is the A/D converter, 0/A converter , l is MPU. 2 is a servo system control circuit, l is a read/write control circuit, 4 is a spindle motor rotation speed control circuit, 5 is a controller, 6 is an interface 7 is a disk device, 8 is a temperature sensor, 9 is a temperature measurement circuit 31 is a control signal generator, 32 is a controlled object, 33 is a controlled object model, and 34 is a characteristic corrector.

Claims (7)

[Claims] (1) A controlled part (1), a drive part (2) that moves and positions the controlled part (1), and a drive part (2) that moves and positions the controlled part (1);
), a position measuring unit (3) that measures the position of the drive unit (
2), the vibration of a system including at least the controlled part (1) and the driving part (2) is modeled, and the model (8) is used to model the vibration of the system including at least the controlled part (1) and the driving part (2). ), and corrects the control of the control unit (4); and second correction means that corrects the model (8) when the temperature of the system changes. (6), and the model (
8) using the difference between the estimated position of the controlled part (1) estimated by the first correction means (5) and the position of the controlled part (1) measured by the position measuring part (3). A positioning control device comprising: a third correction means (7) for sequentially correcting the model (8). (2) At least a disk (11) and a head (13,
a control means (21) for controlling the movement of the heads (13, 14) of a disk device, which is housed in a housing and the housing is supported via a vibration isolating member;
, 14) is subjected to external vibration based on the temperature-dependent vibration isolating member, the vibration characteristics of the head (13, 14) due to external vibration when the temperature of the vibration isolating member is temperature T_1 are determined by the vibration characteristics of the head (13, 14) caused by the external vibration. a first correction means (21) that corrects the control of the control means (21) based on the estimated vibration characteristics of the head (13, 14); When the temperature changes to another temperature T_2, the model due to external vibration in the case of the temperature T_1 is changed to the temperature T_2.
a second correction means (21) that corrects the correction of the first correction means by correcting the model due to external vibration in the case of the first correction means (21) and the second correction means (
21) Compare and differentiate the estimated position of the head (13, 14) and the actual position of the head (13, 14), and further modify the model so that the difference value becomes zero. A third correction means (21) corrects the control of the control means (21) using the model corrected by the third correction means, and adjusts the head (21) to the target position on the disk. 13, 14). (3) The positioning control device according to claim 2, wherein the control means and the first correction means in which the model is programmed are provided in a processing computer (21). (4) The positioning device according to claim 2 or 3, wherein the control means and the second correction means are provided in a processing computer (21). (5) The second correction means is notified of the temperature by temperature measurement means (28, 29) that measures the temperature of the vibration isolating member. positioning control device. (6) The temperature measuring means (28, 29) is configured to calculate the temperature of the vibration isolating member from a temperature sensor (28) that detects a temperature change of the vibration isolating member and a detection value detected by the temperature sensor (28). 6. The positioning control device according to claim 5, further comprising a calculation means (29) for calculating the position, and the calculation means (29) being provided outside the disk device. (7) The positioning control device according to claim 5, wherein the temperature measuring means (28, 29) is provided in an external device that uses the disk device.