JPS63223801A - Control device - Google Patents

Abstract

PURPOSE:To prevent deterioration of the control characteristics due to the mixture of disturbance by using a resetting circuit which forcibly sets a register storing the error signals produced in a low-band compensating filter at zero. CONSTITUTION:A tracking servo of a CD player contains a digital low-band compensating filter 17 including the total addition of a register 15, an off-track detector 18 which detects an off-track state of the tracking servo from the phase difference between an RF signal and a tracking error signal, and a resetting circuit 21 which receives the output of the detector 18 and sets forcibly the register 15 at zero or the value accordant with zero. As a result, the DC component of a control error is substantially set at zero and at the same time it is possible to prevent deterioration of the control characteristics and to quickly perform a lead-in action again in such abnormal cases where the control gets out of its normal routine, the disturbance is mixed into a control system, etc.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a control device.

2 shows a conventional example of a feedback control system in which the direct current gain of a low-pass compensation filter is theoretically infinite using a cumulative addition film.

In FIG. 2, 1 is a detector that detects the difference between the reference amount and the drive amount and outputs it as an error signal, 2 is an error signal output terminal of the detector 1, 3 is an adder, 4 is a register, and 5 is a A cumulative addition low-pass compensation filter consisting of an adder 3 and a register 4 and receiving the output of the detector 1 as an input; 6 a phase compensation filter receiving the output of the cumulative addition low-pass compensation filter 5; 7 a phase compensation filter as described above; A drive circuit 8 which receives the output of the phase compensation filter 6 as an input is an object to be driven by the drive circuit 7.

In the feedback control system configured as above, −
Since the DC gain of the circular transfer characteristic is theoretically infinite, the DC component of the control error signal can be theoretically reduced to zero.

Problems to be Solved by the Invention However, with the above configuration, when an abnormal situation such as loss of control or disturbance entering the control system occurs, the signal input to the cumulative addition filter 5 contains a DC component. In this case, the DC component would be accumulated in the register 4, resulting in problems such as deterioration of control characteristics and inability to re-draw.

The present invention takes the above-mentioned problems into consideration and provides a configuration that prevents deterioration of control characteristics and allows prompt re-retraction in the event of an abnormal situation such as loss of control or disturbance entering the control system. It is something to do.

Means for Solving the Problems In order to solve the above problems, the present invention provides a low-pass compensation filter using a digital filter with infinite DC gain or a characteristic similar thereto, and a control system that detects changes in the control state. It comprises a state detector and a reset circuit that receives the output of the control state detector as an input and forcibly resets the register in which the error signal in the low-pass compensation filter is stored to O or a value similar to O. be.

Effect of the present invention With the above-described configuration, when an abnormal situation such as loss of control or disturbance entering the control system occurs, the abnormal situation is detected by the control state detector, and the output of the control state detector is received. By outputting a reset pulse from the reset circuit, the DC component accumulated in the register of the low-pass compensation digital filter is forcibly reset to 0 or a value close to 0 in the event of an abnormal situation, thereby preventing deterioration of control characteristics and promptly This allows it to be retracted.

EXAMPLE Hereinafter, an example of the application of the present invention to a tracking servo for a CD player will be described with reference to the drawings.

FIG. 1 is a block diagram when the present invention is applied to a tracking servo for a CD player. In Figure 1,
10 is a detector that detects the relative error between disk displacement and actuator displacement and outputs a tracking error signal; 1)
1 is an error signal output terminal of the detector 10; 12 is a head amplifier that amplifies the error signal output of the detector 10 to a predetermined value;
3 is an A/D converter that A/D converts the output of the head amplifier 12, 14 is an adder, 15 is a register, 16 is a reset terminal of register 15, and 17 is adder 14 and register 15.
18 is an off-track detector that detects that the tracking servo is off based on the phase difference of the RF multiplied signal tracking error signal; 19 is an RF signal input terminal of the off-track detector 18;
20 is a tracking error signal input terminal of the off-track detector 18, 21 is a reset circuit that outputs a reset pulse upon receiving the output of the off-track detector 18 and resets the contents of the register 15 to 0, and 22 is a reset circuit for the reset circuit 21. Pulse output terminal, 23 is a phase compensation filter, 24
2 is a D/A converter; 25 is a drive circuit for driving the actuator 26 in response to the output of the D/A converter 24;
6 is an actuator driven by the drive circuit 25.

Now, if the servo comes off for some reason and the track crosses, a signal different from the error signal originally required by the control system will be generated at the output terminal 1) of the detector 10, and this signal will contain a DC component. If it is, the DC component will be accumulated in the register 15, making it difficult to re-draw it. Therefore, the off-track detector 18 detects that the servo has come off, and upon receiving the output of the off-track detector 18, the reset circuit 21 resets the contents of the register 15 to 0, thereby promptly re-engaging the servo. becomes possible.

As described above, according to this embodiment, the digital low-pass compensation filter uses cumulative addition, the off-track detector detects servo deviation, and the digital low-pass compensation filter receives the output from the off-trunk detector. By providing a reset circuit that resets the servo, it is possible to quickly re-retract the servo if it becomes disconnected.

In this embodiment, the tracking servo deviation is detected based on the phase difference of the RF multiplied signal tracking error signal, but the tracking servo deviation can be detected by various other methods. The method is well known and will not be discussed in detail here.

Further, in this embodiment, the register of the low-pass compensation filter is reset when tracking servo deviation is detected, but the present invention can also be applied to detecting a defect on a disk, detecting disturbance vibration, etc.

Further, in the present embodiment, the low-pass compensation filter is configured by an accumulative adder having the simplest configuration, but it is also possible to configure it by a digital filter having a more complicated configuration.

Effects of the Invention As described above, the present invention includes a low-pass compensation filter using a digital filter having infinite DC gain or similar characteristics, a control state detector that detects a change in a control state, and a control state detector that detects a change in a control state. The DC component of the control error in steady state can be reduced by providing a reset circuit that uses the output of the controller as an input and forcibly resets the register in which the error signal in the low-pass compensation filter is stored to O or a value close to 0. This makes it possible to make the control system nearly zero, and to prevent the control characteristics from deteriorating and to quickly re-retract in the event of an abnormal situation such as loss of control or disturbance entering the control system.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a tracking servo for a CD player according to an embodiment of the present invention, and Fig. 2 shows a feedback control system in which the DC gain of the low-pass compensation filter is theoretically infinite using a conventional cumulative addition filter. It is a block diagram. 14...Adder, 15...Register,
16... Reset terminal of register 15, 17.
...Cumulative addition digital filter, 18...
- Off-track detector, 21...Reset circuit. Name of agent: Patent attorney Toshio Nakao
・+5- ward is also Higashisakawi

Claims (4)

[Claims] (1) a low-pass compensation filter using a digital filter having infinite direct current gain or characteristics similar thereto; a drive circuit that inputs the output of the low-pass compensation filter and outputs a signal for driving a driven object; a detector that detects the relative position or relative velocity between the driven object and the target driven by the output of the drive circuit and outputs an error signal to be input to the low-pass compensation filter; and a control that detects changes in the control state. comprising a state detector and a reset circuit that receives the output of the control state detector and forcibly resets the register in which the error signal in the low-pass compensation filter is stored to 0 or a value close to 0. A control device characterized by: (2) The control device according to claim (1), wherein the low-pass compensation filter is constituted by an accumulative adder using an adder and a register. (3) The control device according to claim (1), wherein the control state detector detects a loss of control. (4) The control device according to claim (1), wherein the control state detector detects disturbance to the control system.