JPH041801A - Gain control device - Google Patents

Abstract

PURPOSE:To attain the use of a gain control device to a feedback servo system which handles the digital signals by performing the comparison of phases with multiplication of signals and controlling the gain of the feedback servo system so as to set the cumulative value of he comparison outputs at almost zero at a prescribed time. CONSTITUTION:A disturbance generator 5 which outputs a waveform having a constant amplitude and the duty of approximately 50% inputs an output clock 6A of a clock generator 6 then supplies the disturbance signal X having the same frequency as 1KHz obtained at a desired gain intersecting point to a disturbance adder 3 and a multiplier 8 for comparison of phases. Then a disturbance application means consists of both generators 5 and 6 and the adder 3. Therefore the coincidence is obtained between the gain intersecting point of a feedback servo system and the frequency of the signal X when the cumulative value of outputs received from the multiplier 8 is equal to almost zero. As a result, the gain of the feedback servo system is detected in an extremely easy way, with high accuracy and in a short time. Thus such a gain control method can be easily applied to the feedback servo system which handles the digital signals.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a gain adjustment device, and particularly to a gain adjustment device that can easily adjust the open loop gain of a feedback servo system.

BACKGROUND OF THE INVENTION In recent years, devices applying feedback servo technology have been widely used. Some of these include sensors, actuators, etc., and the variation in them is large, and the cost of gain adjustment during production is becoming a problem.

FIG. 5 is a block diagram showing the configuration of a conventional gain adjustment device. In FIG. 5, the controllable amplifier 21, the fixed amplifier 22, and the disturbance adder 923 constitute a closed loop. 24 is an oscillator that generates a disturbance signal;
The signal is input to a disturbance adder 23 and a phase comparator 25. 26 is a signal adder which adds the input signal and output signal of the disturbance adder 23 at a predetermined ratio, and the output is sent to the phase comparator 2.
The zero phase comparator 25 input to the input terminal 5 compares the phase of the disturbance signal with the output of the signal addition 926, and the output is sent to the subtracter 27.
is connected to and subtracted from the reference voltage source 28. Subtractor 27
The gain of the controllable amplifier 21 is controlled so that the output of the controllable amplifier 21 becomes zero.

Thereby, the gain of the controllable amplifier 21 can be automatically controlled so as to reach the predetermined frequency power I° gain intersection.

Problems to be Solved by the Invention However, with the development of digital technology in recent years, servo technology has also become so-called digital servo technology, and in the above conventional configuration, the output of the phase comparator 25 is As a result, the output of the subtracter 27 that generates the control voltage of the controllable amplifier also swings positive and negative, so the open loop gain is not constant. Also,
Even if a smoothing circuit (for example, a first-order low-pass filter using a resistor or capacitor) is provided at the output of the phase comparator 25 or the subtractor 27 to stabilize the control voltage, it will take time for the control voltage to become stable, so it will not work quickly. This method cannot be used as is in a feedback servo system that handles digital signals, which is the object of the present invention, because it becomes impossible to perform gain control.

The present invention solves the above conventional problems, and aims to provide a gain adjustment device that can easily and accurately perform gain adjustment in a feedback servo system that handles digital signals in a short time. .

Means for Solving the Problems In order to solve the above problems, the gain adjustment device of the present invention includes:
A gain adjustment device for a feedback servo system that handles a servo error signal as a digital signal, the feedback servo system having a specific frequency using one of a positive arc wave, a triangular wave, and a rectangular wave with a duty of approximately 50%. disturbance applying means for applying a disturbance signal; addition means for calculating the sum or difference of any two signals among the signals before and after the application point of the disturbance signal and the disturbance signal; and a gain of the feedback servo system so that the cumulative value of the output of the phase comparing means becomes approximately zero at a predetermined time. and gain adjustment means for adjusting.

Effect With the above configuration, the gain intersection of the feedback servo system coincides with the frequency of the disturbance signal when the cumulative value of the output from the phase comparison means becomes almost zero, so the gain can be adjusted very easily and accurately in a short time. detected and therefore easily used in feedback servo systems that handle digital signals.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a gain adjustment device showing one embodiment of the present invention.

In a servo system that handles digital signals, an analog servo error signal is converted into a digital signal with a predetermined number of bits using a sampling frequency Fs. For ease of explanation, the sampling frequency Fs = 100 KHz and the desired gain intersection point IK
Let it be Hz.

In FIG. 1, 1 is a fixed amplifier, 2 is a gain adjustment multiplier, and 3 is a disturbance adder. The output of the fixed amplifier 1 is returned to its own input via the disturbance adder 3 and the gain adjustment multiplier 2, forming a closed loop.

5 is a disturbance generator that generates a waveform with a constant amplitude and a duty of approximately 50%; the output clock 6 of the clock generator 6;
A is input, and a disturbance signal X having the same frequency as the frequency IKHz of the desired gain intersection is supplied to the disturbance adder 3 and the phase comparison multiplier 8. Clock generator 6 and disturbance generator 5
The disturbance adder 3 constitutes a disturbance applying means. 4
is a signal adder that adds the output Y1 of the fixed amplifier 1 and the output Y2 of the disturbance adder 3, and supplies the output Y to the phase comparison multiplier 8. The phase comparison multiplier 8 multiplies the disturbance signal X by the output Y of the signal adder 4, and supplies the output 8A to the cumulative adder 9.

On the other hand, the output 6A of the clock generator 6 is divided by the divider 7 into a signal 7A having the same frequency as the sampling frequency, and is supplied to the cumulative adder 9. The cumulative adder 9 cumulatively adds the input signal 8A to the signal 7A for each sampling frequency, and outputs the cumulative value 9A to the control circuit 10. The control circuit 10 inputs the output 6A of the clock generator 6, generates a clear signal 10B for each predetermined wave number of the disturbance signal, and clears the cumulative addition value every time the output 9A of the cumulative adder 9 is taken in. . The control circuit IO controls the multiplier 10A of the gain adjustment multiplier 2 based on the input cumulative value 9A.

FIG. 2 shows an example of the configuration of the cumulative adder 9. The output 8A from the phase comparison multiplier 8 is input to the full adder 91, and the output 91A is input to the latch section 92 driven by the signal 7A.
The output 9A is supplied to the other input of the full adder 91 and also to the control circuit 10. In addition, the control circuit 1
The latch section 92 is cleared by the clear signal 10B from 0.

The disturbance adder 3 and the signal adder 4 can be configured by full adders. The disturbance generator 5 can be easily constructed from an address counter and a ROM (read only memory) using the output 6A of the clock generator 6 as a driving clock. The gain adjustment multiplier 2 and the phase comparison multiplier 8 can be configured by multipliers. Control circuit 10 is suitably a microprocessor.

The gain adjustment device configured as above is described below.
Let's explain its operation.

In FIG. 1, when the gain intersection of the open loop gains of the fixed amplifier 1, disturbance addition Wj3, and gain adjustment multiplier 2 that constitute a closed loop matches the frequency of the disturbance signal X,
It is known that the output Y of the signal adder 4 leads the disturbance signal X in phase by 90 degrees.

A timing chart of each signal at this time is shown in FIG. The disturbance signal X has a constant amplitude and a frequency of 1) Hz.
A sine wave of is supplied from the disturbance generator 5.

When the open loop gain becomes 1 Hz, the output Y of the signal adder 4 leads the disturbance signal X by 90 degrees in phase, so the output 8A of the phase comparison multiplier 8 becomes a sine wave with a frequency of 2 Hz. Become.

The output 8A of the phase comparison multiplier 8 is input to the full adder 91 of the cumulative adder 119 having the configuration shown in FIG.

Here, first, when the clear signal 10B is input, the latch section 92 is cleared and the output 9A becomes zero.

Therefore, the output 91A of the full adder 91 is the input signal 8A, which is output as is, and is latched by the signal 7A having the same frequency as the sampling frequency, and the output 9A matches the input signal 8A. When the signal 8A is inputted again in the next sampling period, the value added to the latch output 9A is latched again by the signal 7A and becomes the output 9A, and cumulative addition is performed.

As shown in FIG. 3, the output 9A of the accumulative adder 9 is cleared by a clear signal 10B which periodically changes while taking a negative value and is output every l disturbance wave. The control circuit 10 takes in the cumulative value 9A immediately before generating the clear signal 10B. In this case, as shown in Fig. 3, the cumulative value 9A immediately before the clear signal 10B is generated is almost zero, so the multiplier 10A to the gain adjustment multiplier 2 can be kept unchanged and kept at the previous state. Bye.

Also, if the gain is too high, as shown in Figure 4,
The output Y of the signal adder 4 leads the disturbance signal X by 90 degrees or more in phase. In this case, as shown in FIG. 4, the cumulative value 9A takes a negative value just before the clear signal 10B is generated. Therefore, the output 10A of the control circuit 10 is made smaller than in the case of FIG. 3 to lower the gain. On the other hand, if the cumulative value 9A is a positive value, if you increase the output 10A and increase the gain (not shown), the gain will automatically match the frequency of the disturbance signal X. can be controlled.

In this embodiment, the disturbance signal is a sine wave with a constant amplitude, but triangular waves or rectangular waves can be easily generated by changing the coding of the ROM (read only memory). In particular, it is clear that the rectangular wave can be easily generated by using the most significant bit of the address counter of the disturbance generator 5 in this embodiment without using a ROM (read only memory).

Also, if the desired disturbance frequency cannot be easily obtained in terms of hardware, adjust the frequency close to the desired gain intersection as the disturbance frequency, and then correct it by increasing or decreasing the gain by the difference. Bye. moreover,
When considering variations in adjustment accuracy and deterioration of adjustment accuracy due to noise, etc., it is sufficient to increase the wave number of the disturbance signal when calculating the cumulative value. Furthermore, when the adjustment time is an issue, the time can be shortened by varying the multiplier for gain adjustment in steps based on the absolute value of the obtained cumulative value.

Effects of the Invention As described above, according to the present invention, one of a sine wave, a triangular wave, and a rectangular wave with a duty of approximately 50% is used as the disturbance signal waveform, and phase comparison is performed by multiplying each signal. By adjusting the gain of the feedback servo system so that the cumulative value of the output becomes almost zero at a predetermined time, it can be used in a feedback servo system that handles digital signals, and
The desired gain adjustment can be automatically and precisely performed in a short time.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of a gain adjustment device according to an embodiment of the present invention, Fig. 2 is a block diagram showing an example of the structure of the accumulative adder in Fig. 1, and Figs. FIG. 5 is a timing chart for explaining the operation shown in FIG. 5, and FIG. 5 is a block diagram showing the configuration of a conventional gain adjustment device. 1.--Fixed amplifier, 2.. Multiplier for gain adjustment, 3.
... Disturbance adder, 4... Signal adder, 5... Disturbance generator, 6-... Clock generator, 7... Branching unit, 8
... Multiplication bud for phase comparison, 9... Accumulation adder, 10.
...Control wholesale circuit.

Claims (1)

[Claims] 1. A gain adjustment device for a feedback servo system that handles a servo error signal as a digital signal, the feedback servo system having a duty of approximately 50%.
disturbance applying means for applying a disturbance signal of a specific frequency using one of a sine wave, a triangular wave, and a rectangular wave, and a sum of signals before and after the application point of the disturbance signal and any two signals of the disturbance signal. Alternatively, an addition means for taking a difference, a phase comparison means for comparing the phases by multiplying another signal of the arbitrary two signals and the output of the addition means, and a cumulative value of the output of the phase comparison means is determined in advance. gain adjusting means for adjusting the gain of the feedback servo system so that the gain becomes approximately zero in a given time.