JPS63273016A - Resonance alarm - Google Patents

Abstract

PURPOSE:To remove the effect of an amplitude noise mixed in the output signal of a sensor and obtain a reliable alarm signal by multiplying measurement signal obtained by the sensor by a delay signal obtained by delaying the measurement signal for a prescribed time and averaging a resultant multiplication output. CONSTITUTION:A delay circuit 4 delays a measurement signal chi(t) obtained by a sensor 1 for a prescribed time tau to output a delayed measurement signal chi(t-tau) and changes the delay time tau on the basis of a signal from a judging circuit 7. A multiplying circuit 5 is inputted with the signals chi(t) and chi(t-tau) to conduct a multiplication on both the signals and an obtained multiplication output is averaged in an averaging circuit 6. Inputted with the output of the circuit 6, the judging circuit 7 judges the resonance of an object to be measured and outputs a signal for changing the time tau of the circuit 4, namely, a signal for urging a gradual change from the initial value of the resonant frequency width of the object to be measured initially set by a signal (m) or a signal for initializing the resonant frequency width. The circuit 7 also outputs an alarm signal alpha as required. Thus, by suitably selecting the time tau, the effect of an amplitude noise other than a resonant frequency can be removed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a resonance alarm that generates a resonance alarm by detecting the resonance vibration of a measured object whose resonance frequency changes depending on various conditions. Regarding equipment.

<Conventional technology> The conventional technology will be explained below with reference to the drawings.

FIG. 4 is a block diagram of a conventional resonance alarm device.

In Figure 4, the object to be measured is a building (for example, a building, a storage tank, a pipe in a plant, etc.) or a structure (
Vibrations such as those that are not related to the size of the shape or the content of the structure) can be detected by sensors that output continuous signals such as accelerometers, strain gauges, and pressure gauges (hereinafter, we will explain using an "accelerometer")1 It can be measured using Note that the following explanation will be given using a pipe in a plant as an example of the object to be measured (however, it is not limited to this).

The acceleration signal χ (1>) which is the output of the accelerometer 1 is averaged using an integrator 2 and then set to a reference value S
t is compared to determine resonance, and when the averaged acceleration signal exceeds a reference value St, an alarm signal is generated.

<Problems to be Solved by the Invention> By the way, in this conventional resonance alarm device, when amplitude noise of a certain level is mixed in the output of the accelerometer 1, an alarm signal determined as resonance is output from the comparator 3. There is a problem in that it may be done.

There are also problems such as grammar. For example, let's consider a case where an accelerometer 1 is installed in a vibrator to measure the resonance of a pipe and issue an alarm. Pipes in plants have different resonant frequencies depending on their shape and the state of the flowing contents. For example, the resonant frequency is different when the pipe is full of liquid and when it is zero.

For example, if an earthquake occurs and you want to understand the condition of this pipe, you can use a resonance warning device with the configuration shown in the figure to detect the resonance of the pipe, and if necessary, issue a warning. The contents of the pipes vary in various ways (for example, the degree of filling of the liquid flowing in the pipe and the amount of flow differ depending on the time)
In such places, it is necessary to measure with different reference values, but as a practical matter, it is not possible to accurately detect vibrations by setting values according to the conditions inside the pipe.

Therefore, with such a device, it is not possible to accurately measure the resonance state of the pipe and generate a resonance alarm.

The present invention has been made in view of the problems of the conventional technology, and even if amplitude noise is mixed in the output signal of the sensor, the influence of this amplitude noise can be removed to provide a reliable alarm. It is an object of the present invention to provide a resonance alarm device configured to obtain a signal and to be compatible with any object to be measured.

Means for Solving the Problems> The resonance alarm device of the present invention for achieving the above-mentioned object has the following features:
A resonance alarm device configured to measure vibration of a measured object using a sensor, make a resonance determination, and issue an alarm, comprising: a delay circuit that delays a measurement signal obtained by the sensor for a predetermined time; an averaging circuit that averages the multiplication output of the multiplication circuit; and an averaging circuit that inputs the output of the averaging circuit to determine the resonance of the object to be measured. It is characterized by comprising a determination circuit that outputs a signal for changing the delay time and also outputs an alarm signal as necessary.

<Example> The present invention will be described below based on the drawings. In the following drawings, parts that overlap with those in FIG. 4 are given the same numbers and their explanations will be omitted.

FIG. 1 is a block diagram of a resonance alarm device according to a specific embodiment of the present invention, which is configured to measure the vibration of an object to be measured using a sensor, determine resonance, and issue an alarm.

In FIG. 1, reference numeral 4 denotes an acceleration signal χ(t-
), and also change the delay time τ based on the signal from the determination circuit detailed below (change here refers to the case of sequential updating and the case of returning to the initial setting value after initialization) ) is a delay circuit configured to do this. Here, m is the value of the resonant frequency width of the object to be measured that should be measured by the accelerometer 1 (for example, in the case of the pipe described above, the resonant state of the pipe is measured from the flow rate of zero to the full tank). (or a setting value that can measure the resonant state of the pipe in a range of possible changes in transport flow noise), that is, a signal for setting the delay time corresponding to this value. (Usually, the resonant frequency of the object to be measured is often known to some extent, so such a configuration can be used, but it goes without saying that this width can also be changed arbitrarily depending on the design.) ). 5 is a multiplication circuit which receives the acceleration signal χ(1) and the delay signal χ(-τ) and multiplies these input signals. Reference numeral 6 denotes an averaging circuit provided to average the multiplication output χ(1)·χ(−τ) of the multiplication circuit 5, and can be represented by, for example, an integrating circuit. 1 is a signal that inputs the integral output of the averaging circuit 6, determines the resonance of the object to be measured, and changes the delay time τ of the delay circuit 4, that is, the resonant frequency width of the object to be measured that was initially set with the signal m. This is a determination circuit that outputs a signal β or a signal γ that initializes the value of , which is gradually changed from the beginning, and also outputs an alarm signal α as necessary.
.

FIG. 2 is a diagram for explaining the present invention. The above will be explained below using FIG. 2 from the top of the equation.

Here, the configuration consisting of the delay circuit 4, the multiplication circuit 5, and the integration circuit 6 is a circuit for determining an autocorrelation function. The autocorrelation function shows the change in autocorrelation l1lI loss on the vertical axis,
It can be expressed by plotting the change in delay time on the horizontal axis.

In other words, since the resonant frequency of the object to be measured is within a certain limited range, the value of the delay time τ is set within the resonant frequency width using the signal door, and the signals β and γ according to the judgment results of the judgment circuit 1 are used to sequentially perform this process. By changing the set delay time or initializing it (selecting a time that allows the resonance frequency band to be detected), you can obtain measurement results that remove the effects of amplitude noise, etc. mixed into the sensor signal. will be possible.

Generally, when the measured object is resonating, the acceleration signal χ(1) of the accelerometer 1 has a periodic component 5(t) due to resonance, as shown by χ(t)-8(t)+N(t) and noise N
(t). Here, if we take the autocorrelation function ψ^^ (τ) of the acceleration signal, we get 95AA(τ)−ψss(
τ) +9's N (τ)+9'NS (τ)
+95NN(τ). However, 9'
ss(τ) is the autocorrelation function of the periodic component, ? 'sN(τ)
+ F N S (τ) is the cross-correlation function of the periodic component and the noise component, PNN (τ) is the autocorrelation l1I of the noise component
I! represents a number. By the way, it is generally considered that there is no correlation between the periodic component and the noise component, so the autocorrelation function 55AA(τ) of the acceleration signal is 9'AA(τ) - 9'ss(τ) + 9'NN( τ). 9'A^ (τ) is shown in Figure 2 (
+95ss(τ) can be represented by the broken line in A) by the solid line in FIG. 2(A), and PNN(τ) can be represented by the solid line in FIG. 2 <8>. In this Figure 2 (A>), 5'AA(τ) is
Once it crosses the zero line, its absolute value periodically recovers to double the value when =0. Using this characteristic, the determination circuit 7 detects resonance. In other words, when resonance is not occurring, the autocorrelation of the acceleration signal ψA^ (τ
) becomes the autocorrelation of the noise, as shown in Figure 2 (B), and the autocorrelation function crosses the zero line once, but after that, its absolute value recovers from the value at τ-〇 compared to the time of resonance. Since it becomes smaller, the determination circuit 1 does not determine that it is resonance.

FIG. 3 is a flowchart of FIG. 1.

The explanation will be continued below with reference to FIGS. 1 and 2.

Now, at time t, acceleration signal χ(1
) is read, the delay circuit 4 outputs the acceleration signal χ(1
), an acceleration delay signal .chi. (-.tau.) delayed by the value of the resonant frequency width of the object to be measured set by the signal m according to the object to be measured by the initial delay time is output. Therefore, in the multiplier circuit 5, the acceleration signal χ(1) is multiplied by the acceleration delay signal χ(t-τ) from one hour ago, and the averaging circuit 6 is supplied with the signal χ(1)·χ(t-). ) will be output. In the averaging circuit 6, the time average χ ・χ −τ of this multiplied signal is expressed as (1/(i2−t+)
)・fχ(1)・χ(t−τ)dt It is determined by a circuit configuration based on the calculation formula. This value is the self-phase rIA function when the acceleration signal is delayed by the delay time. Resonance determination of the object to be measured is performed by introducing the value of this autocorrelation function to the determination circuit γ.

In the determination circuit 7, if the averaging circuit output is normal, the delay time of the delay circuit 4 is updated from the initially set delay time to the next delay time. After this update, the acceleration signal of the accelerometer 1 is read again. When the resonance state of the object to be measured can be detected in this way, the determination circuit 7 outputs the alarm signal α, and at the same time initializes the set value of the delay time since there is no need to change the delay time in this case. The signal γ is output to the delay circuit 4, and the delay time τ is initialized. On the other hand, if the judgment circuit 7 does not output the alarm signal α, the signal β causes the delay circuit 4 to gradually change the value of the delay time based on the value of the resonant frequency width of the measured object set by the signal m from the beginning to the end. Then, when you reach the final setting time, return to the parent and repeat this process.

In this way, in the present invention, since the resonance determination of the object to be measured is performed while updating the delay time τ, high accuracy and high speed resonance detection can be achieved.

Note that although the configuration is such that the signals β and γ are inputted from the determination circuit to change the delay time of the delay circuit, the present invention is not limited to this. For example, it is also possible to provide a monitoring circuit (not shown) that monitors the alarm signal of the determination circuit in real time, and to change the delay time based on the signal from this monitoring circuit. Also, if this monitoring circuit is configured as a general command circuit (not shown) that has a delay time setting function, the signal m from the general command circuit can be used without inputting the signal m to the delay circuit. The delay time of the delay circuit can be set and changed as desired. However, from a conceptual point of view, the function of the monitoring circuit and the function of the general command circuit may be built into the determination circuit, and these belong to design matters.

In addition, using the alarm signal, a 7 actuator or the like is attached to the above-mentioned vibrator, and this actuator is operated by the signal related to the above-mentioned alarm device to change the flow rate inside the vibrator and change the resonance frequency of the vibrator. You can also do that.

<Effects of the Invention> As described above, the present invention has been specifically explained along with the examples.
According to the resonance alarm device of the present invention, by appropriately selecting the delay time of the delay circuit based on the resonance frequency of the object to be measured,
Not affected by imaging width noise other than the resonant frequency of the object to be measured. Furthermore, the autocorrelation function method uses both the magnitude and frequency of the signal to determine resonance. Therefore, the reliability of resonance determination is improved due to these factors, and a highly reliable resonance warning device can be realized. At the same time, since the delay time can be changed and set at will according to the conditions of the object to be measured, it can be used for a wide range of purposes (there is no need to select the object to be measured). be able to.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a resonance alarm device showing a specific embodiment of the present invention, Fig. 2 is a diagram for explaining the invention, Fig. 3 is a flowchart, and Fig. 4 is a block diagram of a conventional resonance alarm device. It is a line diagram. 1... Accelerometer, 2... Integrator, 3... Comparator,
4... Delay circuit, 5... Multiplier circuit, 6... Averaging circuit, 7... Figure 1, Figure 2

Claims (1)

[Claims] A resonance alarm device configured to measure vibration of a measured object using a sensor, make a resonance determination, and issue an alarm, comprising: a delay circuit that delays a measurement signal obtained by the sensor for a predetermined time; an averaging circuit that averages the multiplication output of the multiplication circuit; and an averaging circuit that inputs the output of the averaging circuit to determine the resonance of the object to be measured. A resonance alarm device comprising: a determination circuit that outputs a signal for changing a delay time and also outputs an alarm signal as necessary.