JPS6367605A - Servo method - Google Patents

Abstract

PURPOSE:To reduce the steady error against the target value by controlling a controlled system by means of the estimated state value of an electronic circuit serving as a state estimating device for the controlled system and an LPF. CONSTITUTION:The noise mixed into a detection signal 6 of a detector 2 is eliminated by an LPF 3 and this signal 6 is compared with an estimated signal corresponding to the output signal of the LPF 3 in the estimated state value of a state estimating device 13. Then an error produced from said comparison is fed back to the device 13 to always secure coincidence between the state value of a controlled system 1 and the estimated state value of the device 13. Therefore the phase delay of the estimated state value is greatly reduced compared with the output signal of the LPF 3 against the control performed by means of the said output signal by extracting the estimated state value corresponding to the state value of the controlled system 1 out of the device 13 and using it for control. The it is possible to increase the DC gains while the overall stability of a servo system is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a servo method for controlling a mechanism.

BACKGROUND OF THE INVENTION In recent years, servo systems have been widely used, for example, in mechanisms that require accurate, high-speed, and precise movement. below,
An example of the conventional servo system mentioned above will be explained with reference to the drawings. FIG. 3 shows a block diagram of a conventional servo system. In FIG. 3, 1.1 is a controlled object, and 2 is a detection device that detects the state quantity 4 of the controlled object 1. Reference numeral 3 denotes a low-pass filter connected in series to the detection device 2, which functions to remove the noise 5 from the detection signal 6 mixed with the noise 5. The control signal 9, which is the output signal of the low-pass filter 3, is compared with the target value IO, and from the error signal 11, the input signal 7 mixed with the disturbance 8 is passed through the controller 12 to the control target 1.
is input. The controlled object 1 responds according to this input signal, and as a result, the state quantity 4 changes. The conventional servo system is configured such that the controlled object 1 responds to the desired response by repeating this process. (For example, rDC motor control circuit design JCQ Publishing, Chapter 4.1) Problems to be Solved by the Invention However, the following problems occur in the above-mentioned servo system. That is, the low-pass filter 3 connected to remove the mixed noise 5 generally reduces the output signal for the input signal to the low-pass filter 3 at a cutoff frequency ωC or higher, as shown in FIG. phase is delayed. Therefore, Figure 3 shows that in order to ensure stability in the servo system, the controller 1
The DC gain in 2 cannot be increased beyond a certain level.

(For example, "Automatic Control" written by Yasuji Oshima, Imori Publishing) Therefore, if the DC gain is small, the response of the controlled object will be relatively slow, the tracking accuracy to the target value 10 will be poor, or the disturbance suppression characteristics will be poor. Problems such as this arise. In addition, in order to avoid the phase delay of the signal caused by the low-pass filter 3, the blocking wave number ωC of the low-pass filter 3 must be increased, or the low-pass filter 3 itself must not be used. The noise 5 mixed into the detection device 2 causes the operation of the entire servo system shown in FIG. 3 to become unstable, or even if it is stable, accurate tracking to the target value 10 cannot be expected.

Therefore, in the conventional servo system, the low-pass filter 3 is necessary, and therefore there is a problem in that there is a limit in control performance due to the above-mentioned limit on increase in DC gain.

Means for Solving the Problems In order to solve the above problems, the servo method of the present invention includes: a detection device for measuring the state quantity of a controlled object; a low-pass filter connected in series to the detection device; having the same dynamic characteristics as the dynamic characteristics of the controlled object and the low-pass filter with the input signal to the controlled object and the output signal of the low-pass filter as input,
and an electronic circuit configured to serve as a state estimator for the control target and the low-pass filter, and the control target is controlled using estimation state II of the electronic circuit. .

Operation The present invention solves the above problems as follows by using the method described above. That is, the noise mixed in the detection signal of the detection device is removed by the low-pass filter, and the signal is used as an estimated signal corresponding to the output signal of the low-pass filter in the estimated state quantity of the state estimator. compare. By feeding back the error to the state estimator, the state Bi of the controlled object is
If the configuration is configured such that t and the estimated state quantity of the state estimator are always equal to each other, the estimated state quantity corresponding to the state quantity of the controlled object is extracted from the state estimator, and the estimated state quantity is used for control. Compared to the case where control is performed using the output signal of the low-pass filter, the phase delay of the estimated state quantity is significantly smaller than the output signal of the low-pass filter, and as a result, the overall servo system is The DC gain described above can be increased while ensuring stability. Therefore, the above-mentioned conventional problems can be solved.

EXAMPLE A servo method according to an example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a servo system in one embodiment of the present invention. In FIG. 1, 1 is a controlled object, 2 is a detection device that detects the state quantity 4 of the controlled object 1, and 3 is connected in series to the detection device 2 to remove noise 5 from a detection signal 6 mixed with noise 5. A low-pass filter, 13 is a state estimator 13 that receives the input signal 7 to the controlled object 1 and the output signal of the low-pass filter 3, and 9 corresponds to the state quantity 4, so the estimation of the state estimator 13 is This is a status signal and is used as a control signal. Step 2 is the error signal 1 obtained by comparing the target value 10 and the control signal 9.
A control input is generated from 1, and this control input and disturbance 8 are input as an input signal 7 to the controlled object l.

FIG. 2 is a detailed diagram of the state estimator 13. In FIG. 2, 14 is a model of the controlled object 1, to which the input signal 7 is input. 15 is a model of the low-pass filter 3, and 16 is a model of the low-pass filter.The signal amplified by the gain that amplifies the signal after comparing the output of the low-pass filter 15 and the output of the low-pass filter 3 is the control target. The model 14 is fed back to the low-pass filter model 15. The effectiveness of the method of the present invention will be explained below with reference to FIGS. 1 and 2. The controlled object 1 includes a detection device 2,
The dynamic characteristics of the low-pass filter 3 are expressed as follows using a state variable X and an output variable y. Here, A, B, and C are matrices or vectors with constant elements. X is controlled object 1, detection device 2,
In the internal state variables of the low-pass filter 3, y is the output signal of the low-pass filter 3, and U is the input signal 7 to the controlled object 1. Here, the internal estimated state variables of the controlled object 14 and the low-pass filter model 15 are X, the output estimated variables of the low-pass filter model 15 are y,
The state estimator 13 is configured to have the following dynamic characteristics, with the gain 16 being g.

That is, Configure as follows.

Here, if the error between the state variables X of the controlled object 1, the detection device 2, and the low-pass filter 3 and the estimated state variable X of the state estimator 13 is e, then e=x−x=Ax+Bu−Ax−Bu−g (y-y) = (A-gc) x - (A-gc) x= (A
gc)(x-x) = (A-gc)e. Therefore, if g is determined so that the real parts of the eigenvalues of A-gc are all negative, e-o will become e-o over time.

That is, since x=x, an estimated state corresponding to the state quantity 4 which is the output of the controlled object l which cannot be directly detected due to the influence of the noise 5 can be extracted from the state estimator 13 as the control signal 9. As described above, this control signal 9 is constantly defeated by the state quantity 4, and since there is no phase delay in the detection part, the stability of the entire servo system is maintained even if the DC gain in the controller 12 is set high. Therefore, it is possible to solve the problems associated with the above-mentioned limit on the increase in DC gain.

In addition, in the first embodiment, the human power signal 7 to the controlled object 1
The same applies to whether there is a single output MW4 or a plurality of outputs from the controlled object. Further, since the effects of the present invention are independent of the configuration of the controller 12, the present invention is not limited by the configuration of the controller 12.

Effects of the Invention As described above, the servo method of the present invention includes a detection device for measuring the state quantity of a controlled object, a low-pass filter connected in series with the detection device, and an input signal to the controlled object and the low-pass filter. has the same dynamic characteristics as the dynamic characteristics of the controlled object and the low-pass filter, which input the output signal of the wave filter, and is configured to serve as a state estimator for the controlled object and the low-pass filter. By controlling the controlled object using the estimated state quantity of the state estimator, the steady-state error with respect to the target value can be reduced or the response characteristics can be improved, compared to the case where the control target is controlled using the signal from the low-pass filter. , it has effects such as improving the suppression characteristics against disturbances.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a servo system in an embodiment of the present invention, FIG. 2 is a detailed diagram of the state estimator 13 in FIG. 1, FIG. 3 is a block diagram of a conventional servo system, and FIG. 4 is a block diagram of a conventional servo system. 4 is a frequency characteristic diagram of the low-pass filter 3 in FIG. 3. FIG. 1... Controlled object, 2... Detection device, 3
...Low pass filter, 13...State estimator.

Claims (1)

[Claims] A detection device that measures a state quantity of a controlled object, a low-pass filter connected in series to the detection device, and an input signal to the controlled object and an output signal of the low-pass filter as inputs, and the control an electronic circuit having the same dynamic characteristics as the object and the low-pass filter and configured to serve as a state estimator for the object to be controlled and the low-pass filter; A servo method characterized in that the controlled object is controlled using estimated state quantities of the controlled object.