JP2611810B2 - Control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-linear control device.

(Prior Art) In recent years, control devices are often digitized with advances in semiconductors and digital signal processing technology, and the digitization has made it possible to easily realize nonlinear control. Hereinafter, a simple conventional example of the above-described nonlinear control device will be described with reference to the drawings.

FIG. 5 is a block diagram showing the configuration of a conventional simple nonlinear control device, and FIG. 6 is a waveform diagram for schematically showing the operation in the configuration of FIG. In FIG. 5, reference numeral 13 denotes a drive target of the control device, 30 denotes an error detection device that detects an error between a displacement of the drive target 13 and a target position and outputs an error signal,
31 is a comparing means for comparing the error signal with a predetermined reference value and outputting "1" as a control signal when the error signal exceeds the reference value; otherwise outputting "0"; A reference value input terminal, 33 is an error signal input terminal of the comparing means 31, 34 is a control signal output terminal of the comparing means 31, and 35 is a target to be driven only when the comparing means 31 outputs "1" as a control signal. A driving device for driving the driving device 13 is a driving signal output terminal of the driving device 35.

The operation of the conventional control device configured as described above will be described below.

In FIG. 6, (a) shows a waveform indicating a target position inputted to the control device, and (b-1) shows an error signal waveform having a small amplitude of a fluctuation component, and its average value and level 0 coincide. (B-2) is a drive signal waveform when an error signal waveform as shown in (b-1) is obtained, and (c-1) is an error signal waveform having a large amplitude of a fluctuation component, and its average value and level 0 are different. Do not match. (C-2) shows the drive signal waveform when the error signal waveform as shown in (c-1) is obtained. The broken line in the figure indicates a predetermined reference value, and the dashed line indicates the average value of each waveform. I have.

In this configuration, a predetermined reference value (broken line in the figure) is set in advance, and only when the error signal exceeds the reference value, the drive signals (b-2) and (c-2) having constant values are output. This is a kind of simple non-linear control device to be added to the drive target 13. (However, the drive signal must be a value sufficient to drive the drive target.) Now, as shown in FIG. 6 (a), the target position of this control device is averaged while including fine fluctuation components. It is assumed that the value is increasing, and the control system follows the average value of this target position (dashed line in the figure). At this time, the control system ideally operates as shown in FIGS. 6 (b-1) and (b-2). That is, the error signal (b-1) is a reference value (broken line in the figure).
When the driving signal (b−
2) is output, the error signal can only rise to a point slightly above the reference value, and the average value of the error signal is almost 0.
Can be suppressed.

(Problems to be Solved by the Invention) However, in the above configuration, since the reference value to be compared with the error signal is a fixed value, FIG. 6 (b-1)
When the amplitude (0 to peak) of the fluctuation component of the error signal is substantially equal to the reference value as shown in FIG. 6, the average value of the error signal can be suppressed to almost 0, but as shown in FIG. If the amplitude of the fluctuation component (0 to peak) is not equal to the reference value,
That is, unless the average value of the error signal (dashed line in the figure) and the 0 level (solid line in the figure) match (b-1), the average value of the error signal does not become 0 and a steady error occurs. The steady error has a problem that it depends on the amplitude of the fluctuation component of the error signal and cannot be controlled by the control device.

The present invention has been made in view of the above problems, and in a nonlinear control system that follows an average value of a signal including a fluctuation component, a control capable of always controlling a steady-state error to an arbitrary value regardless of the amplitude of the fluctuation component. It is intended to obtain a device.

(Means for Solving the Problems) In order to achieve the above object, a control device according to the present invention receives an error signal, calculates a difference between a maximum value and a minimum value of the error signal, and calculates a difference between the maximum value and the minimum value. Reference value determining means for determining and outputting a reference value by multiplying by a coefficient, and comparing means for receiving the error signal and the reference value as input, comparing the error signal with the reference value, and outputting a control signal And driving means for driving a driving target by using the control signal as an input.

(Operation) According to the above configuration, the present invention sets a reference value according to the amplitude of the fluctuation component of the error signal, and outputs a drive signal based on a comparison result between the error signal and the reference value. In addition, the steady-state error can always be controlled to an arbitrary value regardless of the amplitude of the fluctuation component.

Embodiment Hereinafter, a control device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a control device according to a first embodiment of the present invention, and FIG. 2 is a waveform diagram schematically showing the operation of the present embodiment. In FIG. 1, reference numeral 1 denotes an error detecting means for detecting an error of a control amount of a driving target from a target value and outputting an error signal, and 2 denotes a reference value determining means for inputting the error signal to determine and output a reference value. And is composed of the following 3 to 6. That is, 3 is a maximum value detecting means for detecting and outputting the maximum value of the error signal, 4 is a minimum value detecting means for detecting and outputting the minimum value of the error signal, and 5 is subtraction for obtaining a difference between the maximum value and the minimum value. Means 6 for performing a predetermined operation on the output of the subtraction means 5 and outputting it as a reference value; and 7 for comparing the error signal with the reference value and setting "1" as a control signal when the error signal exceeds the reference value. A comparison means for outputting a "0" signal when the error signal does not exceed the reference value, a reference value input terminal 8 of the comparison means 7, an error signal input terminal 9 of the comparison means 7, and a reference numeral 10 of the comparison means 7. A control signal output terminal; 11, a drive unit for outputting a drive signal having a constant value and driving a drive target only when the control signal output from the comparison unit 7 is “1”; 12, a drive signal output terminal of the drive unit 11; Reference numeral 13 denotes a drive target of this control system.

Regarding the control device configured as described above,
This will be described with reference to FIGS.

In FIG. 2, (a-1) shows an error signal waveform, and (a-)
2) is a drive signal waveform when the error signal waveform (a-1) is obtained, (b-1) is an error signal waveform, and (b-2) is a time when the error signal waveform (b-1) is obtained. In FIG. 2 (a-1), the drive signal waveform of FIG.
While including a fine fluctuation component as shown in (b-1),
It is assumed that the average value increases in the upward direction in the figure.

In the present embodiment, it is assumed that the reference value is determined and updated by the reference value determining means 2 at regular time intervals T. That is,
The maximum value detecting means 3 detects the maximum value (= MAX) of the error signal in the cycle T, and the minimum value detecting means 4 detects the minimum value (= MIN) of the error signal in the cycle T, The difference between the maximum value and the minimum value (MAX-MI
N). Here, if the period T is sufficiently short with respect to the change in the average value of the error signal and sufficiently long with respect to the change in the fluctuation component, the obtained difference = MAX-MIN becomes (a-1) and (b) in FIG. As shown in -1), it is substantially equal to the amplitude value (peak to peak) of the fluctuation component in the error signal. Next, the obtained difference (MAX-MIN) is multiplied by a coefficient 1/2 by the calculating means 6 to obtain (M
(AX-MIN) / 2 is set as the reference value. Similar processing is repeated for each cycle T.

By performing the above processing, FIG.
The reference value is used both when the amplitude of the fluctuation component in the error signal is relatively small as shown in 1) and when the amplitude of the fluctuation component in the error signal is relatively large as shown in FIG. Is automatically set to の of the amplitude value (peak to peak) of the fluctuation component, so that the average value of the fluctuation component in the error signal can be made almost zero, that is, the steady-state error can be made almost zero.

As described above, according to the present embodiment, a reference value determining unit that determines and outputs a reference value with an error signal as an input, and compares the error signal with the reference value to generate a control signal when the error signal exceeds the reference value. A comparing unit that outputs “1”; and a driving unit that outputs a driving signal of a constant value and drives a driving target only when the comparing unit outputs “1” as a control signal. Maximum value detection means for detecting and outputting the maximum value of the error signal; minimum value detection means for detecting and outputting the minimum value of the error signal; subtraction means for obtaining a difference between the maximum value and the minimum value; By using the arithmetic means for outputting the coefficient as a reference value and outputting it as a reference value, the steady-state error can always be made substantially zero irrespective of the amplitude of the fluctuation component in the error signal.

Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 3 is a block diagram showing a configuration of a traverse servo device of a CD player in a control device according to a second embodiment of the present invention. In FIG. 3, 14 is a compact disk, 15 is a rotating device for rotating the compact disk 14, 16 is an optical pickup for reading out information signals and tracking error information written on the compact disk 14, and 17 is an optical pickup 16 in the disk radial direction. A tracking actuator that moves to follow the track, and 18 is a tracking actuator that moves with the average position of the optical pickup
A traverse actuator 17 for moving the disk 17 in the radial direction of the disk, a tracking error generator 19 for generating a tracking error signal from the output of the optical pickup 16, and a tracking controller 20 for applying a tracking servo (generally using a loop filter or the like) Means is known), 21 is a driving device for driving the tracking actuator 17, 22 is a traverse error generating device for extracting a low-frequency component of the tracking error signal to generate a traverse error signal, and 23 is a constant from the traverse error signal. A reference value determination device that determines two reference values (reference value 1 and reference value 2) for each cycle T, 24 is a reference value 1 output terminal of the reference value determination device 23, and 25 is a reference value 2 of the reference value determination device 23 An output terminal 26 is a comparison device for comparing the traverse error signal with reference values 1 and 2 to output a control signal, and 27 is a comparison device 26 Control signal output terminal,
28 is a traverse driving device that drives the traverse actuator 18 with the control signal output by the comparison device 26 as an input,
29 is a drive signal output terminal of the traverse drive device 28.

The traverse servo device configured as described above will be described below with reference to FIGS.

First, FIG. 4 is a waveform diagram of a traverse error signal for schematically showing the operation of the present embodiment.
The dashed line is the reference value 2.

In FIG. 3, since the traverse error signal is generated by extracting the low-frequency component of the tracking error signal, the eccentric component of the disk as shown in FIG. 4 is mixed in the traverse error signal. However, the original purpose of the traverse servo is to maintain the average position of the optical pickup 16 at the mechanical center of the tracking actuator 17,
From the viewpoint of power consumption, it is not preferable to make the traverse servo follow this eccentric component. Therefore, the traverse servo follows the traverse error signal and the average value.

In FIG. 3, the reference value determination device 23 uses a fixed period T
The maximum value (= MAX) and the minimum value (= MIN) of the traverse error signal are detected every time, and the following two reference values are set from the obtained maximum value and minimum value, and are fixed. It shall be updated every period T.

Here, in FIG. 4, the comparison device 26 determines that the control signal is “1” if the traverse error signal is above the reference value 1 and “−” if the traverse error signal is below the reference value 2 in FIG.
"1" is output, otherwise "0" is output. The traverse driving device 28 outputs a constant positive value if the control signal output from the comparing device 26 is "1", and outputs a negative constant value if the control signal is "-1". It is assumed that the traverse actuator 18 is driven at a constant value of .times., And that the drive signal is not output if the control signal is "0".

During normal servo, assuming that the average value of the traverse error signal moves upward in FIG. 4 as the disk is reproduced from the inner circumference to the outer circumference, if the average value of the traverse error signal moves upward in FIG. Is driven at a constant value of
The traverse error signal does not move above the reference value 1,
The steady-state error can be made almost zero as shown in FIG. 4 regardless of the amplitude of the disk eccentric component in the traverse error signal.

Further, a reference value 2 is provided in a direction opposite to the reference value 1. Therefore, when a track jump is performed from the outer circumference to the inner circumference of the disk, the average position of the tracking actuator 17 moves and the traverse error signal moves downward in FIG. Since the traverse actuator 18 is driven at a constant negative value below the value 2, the traverse error signal does not move below the reference value 2 and the traverse servo follows the movement of the average position of the tracking actuator 17. Can be.

(If the reference value 2 is-(MAX-MIN) / 2, hunting occurs with the reference group 1, so that a margin "a" is provided as shown in equation (2).) As described above, according to the present embodiment, the reference value determination device 23 that determines and outputs two reference values from the traverse error signal.
By providing a comparison device 26 that compares the traverse error signal with two reference values and outputs a control signal, and a traverse drive device 28 that drives the traverse actuator 18 with the control signal output by the comparison device as an input, Regardless of the amplitude of the disk eccentricity component in the taraverse error signal, the steady-state error during normal servo can be reduced to almost zero. Even when a track jump is performed in the reverse direction, the traverse servo is used to move the average position of the tracking actuator 17. It can be followed and hunting can be prevented.

Note that the reference value determination means 2 and the second
In the reference value determination device 23 of this embodiment, the determined reference value is changed every fixed time period T. However, the update period may not be a fixed period, and the reference value once determined is not updated ( Alternatively, it may be used (not updated until some state is detected).

Further, one reference value is set in the reference value determination means 2 in the first embodiment, and two reference values are set in the reference value determination device 23 in the embodiment of FIG. 2, but any number of reference values may be set. Various controls can be performed by performing various comparison judgments by a comparison unit that compares the error signal with the reference value.

(Effects of the Invention) As described above, the present invention provides a reference value determining means for determining and outputting a reference value with an error signal as an input, an error signal and a reference value as inputs, and comparing the error signal with the reference value. And a driving means for driving the driven object with the control signal as an input, so that the steady-state error is always set to an arbitrary value irrespective of the amplitude of the fluctuation component in the error signal. Can be controlled.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a control device in a first embodiment of the present invention, FIG. 2 is a waveform diagram showing the operation of the control device in FIG. 1, and FIG. 3 is a second embodiment of the present invention. CD in the example
FIG. 4 is a block diagram showing a configuration of a traverse servo device of the player, FIG. 4 is a waveform diagram showing a traverse error signal in FIG. 3, FIG. 5 is a block diagram showing a configuration of a conventional simple nonlinear control device, and FIG. 6 is a waveform diagram schematically showing the operation in the configuration of FIG. DESCRIPTION OF SYMBOLS 1 ... Error detection means, 2 ... Reference value determination means, 3 ... Maximum value detection means, 4 ... Minimum value detection means, 5 ... Subtraction means, 6 ... Calculation means, 7 ... Comparison means, 11 …… Drive means, 13 …… Drive target.

Claims (1)

(57) [Claims] 1. An error detecting means for detecting an error of a control amount of a drive target from a target value and outputting an error signal, receiving the error signal as input, and calculating a difference between a maximum value and a minimum value of the error signal. A reference value determining means for determining and outputting a reference value by multiplying the error signal by a coefficient that makes a steady error substantially zero; and inputting the error signal and the reference value, and comparing the error signal with the reference value. A control unit that outputs a control signal to the control unit, and a driving unit that drives the drive target using the control signal as an input.