JPH06250703A - Feedback controller - Google Patents

Abstract

PURPOSE:To reduce control deviation and perform highly precise feedback control by calculating such a set value that the difference between a feedback quantity and a control standard becomes zero and calculating a manipulated variable from the set value and feedback quantity, and performing control. CONSTITUTION:A computing element 22 inputs the feedback quantity VF at its one input terminal and the control reference Vr at the other input terminal, and calculates the set value V'r from the control reference Vr and feedback quantity VF and outputs it to a subtraction part 7. The subtraction part 7 calculates the difference between the set value V'r and feedback quantity VF to calculate control deviation VS and outputs it to a motor driving part 9 through a filter amplifier 8. The motor driving part 9 generates the manipulated variable on the basis of the inputted control deviation VS and controls the operation of a reel motor 1. Thus, the computing element 22 which calculates the set value V'r with which the difference between the control reference Vr and feedback quantity VF becomes zero is provided and the manipulated variable is calculated from the set value V'r and feedback quantity VF to perform the control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for feedback control of a controlled object such as a reel motor, a capstan motor or a drum motor mounted on a magnetic recording / reproducing apparatus such as a video tape recorder (VTR). Regarding the control device.

[0002]

2. Description of the Related Art Generally, a feedback control device of this type detects a controlled variable of a controlled object in order to keep the controlled object at a control reference (target value), and feedback-controls the controlled object based on this controlled variable. To do.

FIG. 4 shows a feedback control device used for feedback-controlling a reel motor 1 which constitutes a tape running system of a VTR. Rotational force of the reel motor 1 is transmitted to a reel base 2 and the reel motor 1 is rotated. The table 2 is rotationally driven. Here, tension (tape tension T) is applied to the tape 3 of the cassette loaded on the reel base 2, and accordingly the tension arm 4 is rotationally biased, but the balance is maintained by the spring force of the spring member 5. Be drunk At this time, the tension arm 4 changes its rotation amount by the position sensor 6
The rotation amount (feedback amount) VF detected by the output signal is output to one input terminal of the subtracting section 7. The control reference (target value) Vr is input to the other input terminal of the subtraction unit 7, and the control deviation Vs is obtained by taking the difference between the rotation amount VF and the control reference Vr.
To calculate. The control deviation Vs is subjected to gain adjustment and phase adjustment by the filter amplifier 8 and then input to the motor drive unit 9. The motor drive unit 9 receives the input control deviation Vs
The reel motor 1 is feedback-controlled so that the tape tension T maintains the control reference Vr based on the calculated motor operation amount.

When a feedback control device for such a tape running system is made into a block diagram, as shown in FIG. 5, a transfer function (input-output conversion coefficient) G1 from the filter amplifier 8 to the motor drive unit 9 of FIG. 4 is obtained. 10, transfer function G2 11 of reel motor 1, tape tension T of tape 3
It is represented by a transfer function G3 12 from the feedback amount VF to the feedback amount VF. As the operation amount, the disturbance A such as the shaft loss of the reel motor 1 and the tape running system load is added. That is, the tape tension T is T = (G1 G2 / (1 + G1 G2 G3)) Vr + (G2 / (1 + G1 G2 G3)) A (1) The feedback amount VF is VF = (G1 G2 G3 / (1 + G1) G2 G3)) Vr + (G2 G3 / (1 + G1 G2 G3)) A (2) The control deviation Vs is expressed by Vs = Vr-VF (3), and the formula (2) is added to the formula (1). When substituted, the control deviation Vs is represented by Vs = (1 / (1 + G1 G2 G3)) Vr- (G2 G3 / (1 + G1 G2 G3)) A (4). For example, equation (4) is
Since A = 0, 1 + G1 G2 G3 = ∞, and Vs = 0 (5), the control deviation Vs does not occur. As a result, the equations (1) and (2) are expressed as follows: T = (1 / G3) Vr (1 + G1 G2 G3 to G1 G2 G3) (6) VF = Vr (1 + G1 G2 G3 to G1 G2 G3) (7) ), The tape tension T (control amount (control output)) and the feedback amount VF are uniquely determined by the control reference Vr.

However, in actuality, in the control system of the above feedback controller, the disturbance A is A ≠ 0 and the transfer function G1 1
0, the gain of the transfer function G2 11 is finite, so that the control deviation Vs shown in the equation (4) is generated, and there is a problem that the feedback control accuracy is restricted. That is, the first term (1 / (1 + G1 G2 G3)) Vr (8) on the right side of the equation (4) is the steady-state deviation of the control system, and the second term − (G2 G3 / (1 + G1 G2 G3)) A … (9)

Is a control deviation due to the disturbance A. Therefore, in order to make the control deviation Vs smaller than a desired value, it is required to set the transfer functions G1, G2, G3 large or set the disturbance A small.

However, in the means for setting the transfer functions G1, G2 and G3 to be large, there is a limit due to the non-linear characteristic of the circuit, the characteristic of the controlled object, the characteristic of the control system, etc. Therefore, the control deviation Vs is required. It may be difficult to set the value below the value of. According to this, it is difficult to secure a desired control deviation unless the occurrence of the disturbance A is reduced or the gain of the control system is increased by using a high gain amplifier circuit. There is a problem that higher performance of components including the target and higher accuracy of control system (reduction of disturbance) are required.

Further, in the means for setting the disturbance A small,
Since measures other than the control device also need to be dealt with, there is a limit to reducing the disturbance A, and it is difficult to set the disturbance A to the required value or less.

Therefore, in the conventional feedback control device, when the gain of the control system cannot be increased,
When the disturbance A is large, it is difficult to apply it to a highly accurate system that requires the control deviation Vs to be set to a desired value or less with respect to the secular change of the control system and the change of the operating environment. Have a problem.

[0010]

As described above, the conventional feedback control device has a problem that it is difficult to keep the control deviation small and the application system is restricted.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a feedback control device capable of realizing a highly accurate feedback control by reducing the control deviation. And

[0012]

According to the present invention, a detection means for detecting a control amount of a controlled object, and a control amount detected by the detection means as a feedback amount are set so that a difference between the feedback amount and a control reference is zero. Calculating means for calculating a value, subtracting means for calculating a control deviation by obtaining a difference between the set value calculated by the calculating means and the feedback amount, and an operation amount based on the control deviation calculated by the subtracting means Then, the feedback control device is configured to include the operation means for controlling the controlled object.

[0013]

According to the above configuration, the control means calculates the set value at which the difference between the control reference and the feedback amount is zero, and the manipulated variable is calculated based on the set value and the feedback amount. Feedback control is performed with a control amount that is not included. Therefore, the feedback control error can be reduced, and the feedback control accuracy can be improved.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a feedback control device according to an embodiment of the present invention. In FIG.
The same parts as those of the above are denoted by the same reference numerals, and detailed description thereof will be omitted.

That is, as described above, the output end of the position detection sensor 6 for detecting the rotation amount (feedback amount) Vs of the tension arm 4 is connected to one input end of the subtracting section 7. Further, at the output end of the position detection sensor 4,
The input ends of a high-pass filter (HPF) 20 and a low-pass filter (LPF) 21 are connected. Of these, the high-pass filter 20 detects a signal VH obtained by separating the disturbance A shown in FIG. 2 from the feedback amount VF of the alternating current component ΔA1 and the alternating current component having no periodicity ΔA2. On the other hand, the low-pass filter 21 detects a signal VL obtained by separating the signal given by the DC component ADC and ((1 + G1 G2 G3) / G1 G2 G3) Vr of the disturbance A from the feedback amount VF.

The output terminals of the high-pass filter 20 and the low-pass filter 21 are connected to one input terminal of an arithmetic unit 22 whose details will be described later. Calculator 22
Is the control reference Vr input to the other input end,
This control reference Vr and the signal V from the high pass filter 20
The set value V'r is calculated based on H and the signal VL from the low-pass filter 21, and the subtractor 7 outputs the set value V'r.
Output to the other input terminal of. The subtracting section 7 calculates the control deviation VS by taking the difference between the input set value V'r and the feedback amount VF and outputs it to the filter amplifier 8.

The calculator 22 receives the signal VH from the high-pass filter 20 as shown in FIG.
After .DELTA.A1 is detected at a, it is guided to the first arithmetic unit 22b. The first calculation unit 22b receives the input signals ΔA1 and −
Vr1 is calculated by multiplying 1 / G1 and Vr1 =-(1 / G1) .DELTA.A1 (20) is executed and output to one input end of the adder 22c. On the other hand, the signal VL from the low pass filter 21 is input to the second arithmetic unit 22d. Second calculation unit 22d
Is calculated from the input signal VL and the control reference Vr, and Vr2 = ((1 + G1 G2 G3) / G1 G2 G3) Vr- (1 / G1) ADC (21) is executed to input the other input of the adder 22c. Output to the end. The addition unit 22c calculates and sets V'r = ((1 + G1 G2 G3) / G1 G2 G3) Vr- (1 / G1) (ADC + .DELTA.A2) (23) from the equations (20) and (21). The value V'r is calculated and output to the other input terminal of the subtraction unit 7.

Here, the subtracting section 7 calculates the control deviation Vs as described above, and this control deviation Vs is input to the motor drive section 9 via the filter amplifier 8. The motor drive unit 9 generates an operation amount based on the input control deviation Vs and controls the operation of the reel motor 1.

As described above, the feedback control device is provided with the calculator 22 for calculating the set value V'r at which the difference between the control reference Vr and the feedback amount VF is zero, and the set value V calculated by the calculator 22 is provided. The operation amount is calculated based on'r and the feedback amount VF, and the feedback control is performed.

According to this, the feedback control is performed with the simple structure and the feedback control is performed with the control amount not including the control deviation, so that the feedback control error is reduced and the feedback control accuracy can be improved. That is, the feedback amount VF is expressed by the following equation: VF = (G1 G2 G3 / (1 + G1 G2 G3)) V'r + (G2 G3 / (1 + G1 G2 G3)) A (24). In this case, the disturbance A is composed of the direct current component ADC and the alternating current component (ΔA1 + ΔA2) as described above, and is represented by the equation A = ADC + ΔA1 + ΔA2 (25). Therefore, the feedback amount VF is calculated based on the equations (24) and (25) as follows: VF = (G1 G2 G3 / (1 + G1 G2 G3)) V'r + (G2 G3 / (1+ G1 G2 G3)) (ADC + ΔA1 + ΔA2) … (26) Here, the set value V'r is ideally a value in which the feedback amount VF matches the control reference Vr. Therefore, if VF = Vr (27), then V'r = ( (1 + G1 G2 G3) / G1 G2 G3) Vr- (1 / G1) (ADC + .DELTA.A1 + .DELTA.A2) (28) Therefore, the feedback amount VF is calculated by the formula (2
Substituting equation (23) for 8), VF = Vr + (G2 G3 / (1 + G1 G2 G3)) ΔA2 (29)

It is represented by This is the control system gain (1+
G1 G2 G3 / G1 G2 G3), DC component of disturbance ADC
And that the control error due to the periodic AC component ΔA1 does not occur, and by optimally designing the characteristics of the filter amplifier 8 and the like so as to remove only the disturbance of the AC component ΔA2 having no periodicity, It is possible to obtain the feedback amount VF which is substantially equal to the control reference, that is, the desired control amount. As a result, it is possible to perform highly accurate feedback control with a small control deviation, reduce feedback control error, and realize a highly accurate control device.

Further, according to this, occurrence of a control error due to a steady deviation and a disturbance (DC component, periodic component) due to aging of the device or change of operating environment can be effectively prevented, so that reliability can be improved. It also has the advantage of realizing a high control device.

In the above embodiment, the case where the present invention is applied to the tape running system of the VTR has been described. However, the present invention is not limited to this, and feedback control of the capstan motor of the VTR, various driving mechanisms other than the VTR, etc. It can be applied to the feedback control of the mechanical part of, and the same effect is expected. Therefore, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

[0025]

As described above in detail, according to the present invention, it is possible to provide a feedback control device capable of reducing the control deviation and realizing highly accurate feedback control. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a feedback control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of the disturbance of FIG.

3 is a diagram showing a block diagram of the control system of FIG. 1. FIG.

FIG. 4 is a diagram showing a conventional feedback control device.

5 is a diagram showing a block diagram of the control system of FIG.

[Explanation of symbols]

1 ... Reel motor, 2 ... Reel stand, 3 ... Tape, 4 ... Tension arm, 5 ... Spring member, 6 ... Position detection sensor,
7 ... Subtraction unit, 8 ... Filter amplifier, 9 ... Motor drive unit,
10, 11, 12 ... Transfer functions G1 to G3, 20 ... High-pass filter, 21 ... Low-pass filter, 22 ... Operation unit,
22a ... Pattern detection unit, 22b ... First calculation unit, 22
c ... Adder, 22d ... Second calculator.

Claims (1)

[Claims] 1. A detection means for detecting a control amount of a controlled object, and a calculation means for calculating a set value at which a difference between the feedback amount and a control reference is zero, using the control amount detected by the detection means as a feedback amount. A subtracting unit for calculating a control deviation by obtaining a difference between the set value calculated by the calculating unit and the feedback amount; and a control amount calculated based on the control deviation calculated by the subtracting unit to control the controlled object. A feedback control device comprising: