KR20050075808A - Vibration analysis method for body of revolution - Google Patents

Abstract

The present invention relates to a vibration analysis method of a rotating body that can quantitatively analyze the vibration of the rotating body by comparing the output value and phase by using a plurality of vibration sensors in the rotating body, using two or more vibration displacement sensors A method of analyzing vibrations caused by rotation of a rotating body, the method comprising: analyzing a phase difference of each vibration displacement sensor; If the analyzed phase difference is 180 degrees, determining that the rotating body in which the two vibration sensors are positioned performs rotational vibration; If the analyzed phase difference is 0 degrees, it can be achieved by including the step of determining that the rotating body in which the two vibration sensors are located to perform the translational vibration.

Description

VIBRATION ANALYSIS METHOD FOR BODY OF REVOLUTION

The present invention relates to a vibration analysis method of a rotating body, in particular, by using a plurality of vibration sensors in the rotating body by comparing the output value and phase, the vibration analysis method of the rotating body to be able to quantitatively analyze the vibration of the rotating body It is about.

In general, conventional displacement sensors for measuring displacement of a vibrating body include piezoelectric methods, piezoresistive methods, electrostatic methods, ultrasonic methods, and optical methods.

Piezoelectric and piezoresistive methods apply a piezoelectric material or piezoelectric material to a pendulum. Acceleration of the vibrating body causes displacement of the pendulum. It is a way of detecting.

The electrostatic method is a method used in accelerometers or gyroscopes to form a structure of a capacitor structure, such as a comb, to detect the acceleration caused by the vibration or rotation, and the ultrasonic method generates an ultrasonic wave to the target object. It measures the distance and the displacement of the object by measuring the time that is reflected back.

There are two methods of measuring the distance from the intensity of the reflected light and a more precise measuring method using a laser. The first method uses the light as the light from the light source decreases in inverse proportion to the square of the distance. Receive and measure the distance from the strength of the signal. Next, the second measurement method using the laser measures the distance from the position change of the light returned by reflecting the laser to the target object.

Since the optical method measures the distance, it can be divided into two methods by measuring the change of the distance by applying the distance, and measuring the vibration which is the change amount of the displacement or the periodic displacement.

The first is to fix the light source and install the light receiving sensor on the object, or to fix the light reception and attach the light source to the vibrating body, and the second is to install the light source and the light reception in the same position and use the reflection of light. Can be.

With the use of light reflection, the light source and the light receiving end can be arranged in the same circuit or integrated on one chip, which simplifies the wiring and reduces the component cost. However, there must be a flat and sufficiently wide reflecting surface and when the reflectance is low, the output of the light source must be increased or the amplification of the receiving end must be increased.

In the vibration displacement calculation method previously applied using the optical method, it is possible to infer the displacement of vibration using the maximum minimum value of the received optical signal, but there is a problem that cannot provide a specific method for analyzing the vibration form therefrom. have.

Therefore, the present invention has been created to solve the above-mentioned conventional problems, by using a plurality of vibration sensors in the rotating body by comparing the output value and phase, it is possible to quantitatively analyze the vibration of the rotating body The purpose is to provide a total vibration analysis method.

In order to achieve the above object, the present invention provides a method for analyzing vibrations caused by rotation of a rotating body using two or more vibration displacement sensors, the method comprising: analyzing phase differences of the respective vibration displacement sensors; If the analyzed phase difference is 180 degrees, determining that the rotating body in which the two vibration sensors are positioned performs rotational vibration; When the analyzed phase difference is 0 degrees, the rotating body in which the two vibration sensors are positioned is characterized in that it comprises the step of determining that the translational vibration.

The present invention uses a plurality of vibration sensors, in particular two vibration displacement sensors on the rotating body, by measuring the displacement of the vibration and the phase difference between the vibrations from the two sensors, respectively, the vibration of the rotating body connected to the motor to rotate translation, that is, The main point of the present invention is to provide a method of quantitatively analyzing the vibrations of the center of gravity and the rotational vibrations rotating with a certain amount of angle about a specific axis.

That is, the present invention relates to a method for analyzing the regular vibration according to the rotation of the rotating body using two or more vibration sensors, a part of the body of the rotating body is fixed by a device that is elastic, such as a spring, two When the vibration sensor of is installed parallel to the rotation axis or the angle of the rotation axis is not large, if the phase difference is 180 degrees by analyzing the phase difference of each vibration sensor, the vibration of the rotating body in which the two vibration sensors are located is rotational vibration and the phase difference If it is 0 degrees, it can be determined that the translational vibration.

Hereinafter, a method for enabling the above determination will be described with reference to the accompanying drawings.

FIG. 1 is an exemplary view showing a schematic configuration of a general vibration displacement calculation system. As shown in FIG. 1, a mirror 103 attached to a predetermined vibration body 104 and a predetermined distance from the mirror 103 are shown. The light emitting unit 101 is installed at a spaced apart position to irradiate light in a direction toward the mirror 103 according to the vibration of the vibrating body 104, and is installed in parallel with the light emitting unit 101 so that the mirror 103 is disposed. A light receiving unit 102 which receives light reflected through the light and generates a potential difference corresponding to the received light amount, and calculates a vibration displacement generated as the vibrating body vibrates back and forth using the electric potential difference generated by the light receiving unit 102. do.

The light reflector may be a diffuse reflector having a rough surface rather than a mirror.

When the vibrating body 104 of FIG. 1 vibrates back and forth with respect to the light emitting unit 101 and the light receiving unit 102, the light emitted from the light emitting unit 104 is reflected by the mirror 103 to the light receiving unit 102. The length of the path that arrives changes, and since the amount of light incident on the light receiver 102 has a physical relationship inversely proportional to the square of the path length, the current amount of the light receiver 102 also changes.

Hereinafter, the vibration displacement calculation process using the system will be described.

First, when the distance between the light emitting part and the light receiving part is d, the light emitting part when the vibrating body does not vibrate and the light receiving part is the distance away from the mirror, the light emitted from the light emitting part is reflected on the mirror when the vibrating body does not vibrate. The length L of the path reaching the light receiving unit can be obtained by the following equation.

---------------------------- Equation 1

Here, it is assumed that d / 2 is considerably smaller than x.

FIG. 2 is a circuit diagram showing the schematic circuit configuration of the light receiving portion in FIG. Therefore, the following relational expression is established between the output voltage V _out applied to the resistor 106 and the length L of the path.

------------------------------- Equation 2

Here, k is a proportional constant and includes a quantity of light emitted from the light emitting unit, a light receiving unit efficiency, a current-to-voltage gain due to a resistance connected to the light receiving element, and the like. In general, each of these may be assumed to be a constant if a resistance connected to a power supply and a light receiving element supplied to the light emitting portion and the light receiving portion is determined.

Next, the distance between the light source and the reflecting surface is Voltage as close as ), And from its original position (x ₀ ) When the distance is far away, can be expressed by the following equations (3) and (4).

------------------------------ Equation 3

------------------------------- Equation 4

According to the above principle, the graph of the output voltage due to the vibration is output in the form similar to the sine wave (Sine), it is possible to obtain the maximum and minimum of the vibration using the maximum and minimum of Equations 3 and 4. However, the vibration is minute and the maximum and minimum of the output voltage can be relatively affected by the electrical noise.

Therefore, the previously applied vibration displacement calculation method is assumed that the vibration is a regular movement for a predetermined time connected to a general rotating body or a motor, the maximum and minimum values of the vibration is the standard deviation or the average of the difference between the average and each data It can be found by obtaining.

When the vibration displacement calculation method is briefly described, when a regular vibration occurs, as most vibrations have a sine wave shape or a shape close to a sine wave, it is assumed that the vibration is a sine wave and vibrates by a sine wave. The distance between the light receiving portion and the reflector vibrates according to the following equation (5) according to the time (T).

------------------------------ Equation 5

Here, the distance is back and forth with respect to the original position (x ₀ ) when there is no vibration Moving by Has a cycle.

In addition, the output voltage V _out of the light receiving unit due to this displacement is represented by the following equation (6).

----------------------- Equation 6

In the above formula Substituted by

The output voltage V _out measured according to the above principle is digitally converted by an ADC (analog-to-digital converter) to obtain the first output voltage data.

On the other hand, the ADC divides the resolution of the digitized data according to the number of bits. For example, when using a 12-bit ADC for a maximum of 10V, the minimum distinguishable voltage is 10/2 ¹² (V), which is about 2.5mV. Has resolution.

At this time, to obtain a second output voltage (V _'out) processed by the first output voltage, and then the data, Equation (7) in order to minimize the effects of noise.

------------------------------------ Equation 7

The following data (D) means the second output voltage ( _V'out ), so that the amount of noise on average compared to the original output voltage data The number of data is the same as the data number of the initial output voltage when measured continuously.

Street Output voltage D) each data and If the average A is obtained by adding the absolute value of the difference with, the following equation (8) is obtained.

----------------------------- Equation 8

Compared to Is small, i.e. In this case, the above equation can be solved by expanding for α. That is, by developing the above equation and taking only the first term of α, a result as shown in Equation 9 can be obtained.

---------------------------------------- Equation 9

here, Is due to the minimum output voltage This can be interpreted as the average of the output voltage which vibrates or when the reflector does not vibrate. Actually, it is different from the mean, but if α is small, it is almost the same.

For non-continuous digitized data, vibration displacement (A) and average output voltage ( ) Is obtained by dividing the difference between the output voltage and the average voltage as shown in Equations 10 and 11, taking the absolute value, and dividing by the number of data.

Equation 10

Equation 11

Here, N must be the amount of data received for an integer multiple of the period or sufficiently larger than the time of data received for one period.

Equations 10 and 11 may be calculated by adding data for each data conversion of the ADC. That is, no separate data storage space is required, and in Equation 11, the average output voltage ( ) Is obtained from previous calculations, assuming that the vibration mean of the rotor does not change significantly. May be used.

Vibration displacement can be calculated from each vibration displacement sensor using the above method.

Hereinafter, a method of analyzing vibration using two or more vibration displacement sensors in the case of a rotating body will be described.

First, for each data, the average and vibration displacement of the output voltage are calculated by the equations (10) and (11).

According to Equation 12 below, normalized data irrespective of the mean and vibration displacement of the output voltage, that is, sin ( ) To leave only parts.

Equation 12

In the above equation, the vibration displacement (A) and the average output voltage ( ) Is assumed to be constant during the measurement time, and this value is calculated in advance and the data that is continuously input is converted into normalized data using the above equation.

It will be described below that the equation is normalized.

It can be seen that Equation 11 is normalized data by the above calculation.

For two sensors, the data of one sensor is called D ₁ and the data of the other sensor is called D ₂ .

Becomes the phase difference Becomes

Thus, if we replace the two data with normalized data,

The average of the absolute value of the difference between the two normalized data can be obtained by the following equation (13).

----- Equation 13

Therefore, when A _nom is the number of data for a certain period as N,

---------------------------- Equation 14

It can be calculated by the above equation (14),

Phase difference ) Can be calculated by the following equation (15).

------------------------------ Equation 15

The phase difference can be obtained by the above method, and the vibration displacement at the position intermediate or parallel to the sensor position can be predicted, respectively.

That is, the displacement of any point P to be predicted in FIG. Suppose that the plane connecting three points is a rigid body, and the distance between P ₁ where the first sensor is located is l ₁ , and the distance between P ₂ is l ₂ ,

When the above equation is calculated, the vibration displacement at the point P can be obtained by the following equation (16).

--------------- Equation 16

If any point in the equation is the center of two sensor positions (l = l ₁ = l ₂ ), and the vibration displacements of two points P ₁ and P ₂ are equal ( Equation 16 is simplified as in Equation 17 below.

----------------------------------- Equation 17

That is, when the phase difference is 0 degrees, as shown in (a) of FIG. 4, the three points perform the translational vibration moving by the same vibration displacement, and the phase difference is 180 degrees. The two points P ₁ and P ₂ do not move and are oscillated in opposite directions with respect to the point P or the vibration center. In the case of a rotating body, as shown in FIG. will be.

5 is a flowchart illustrating a vibration analysis method of a rotating body according to the present invention. First, the light emitting unit irradiates light toward a mirror that vibrates vertically, horizontally, or front-to-back in accordance with the vibration of the vibrating body (S101). ).

When the light is irradiated toward the vibrating mirror as described above, the light receiving unit receives the light reflected through the mirror (S102). At this time, the light receiving unit generates an output voltage variably according to the amount of light received therein, and calculates the output voltage in two ways.

The first is to calculate the output voltage (second output voltage) from which the noise is removed from the output voltage (S103), and the second is to detect data for a predetermined set period and calculate the average voltage based on the average value (S104). .

Next, a difference value between the second output voltage from which the noise is removed and the average voltage for a predetermined period is calculated (S105), and an average value of the absolute value of the difference value is calculated (S106). When the average value of the output voltage detected by removing the noise and the plurality of detected output voltages is calculated in the above manner, the vibration displacement is calculated based on the average value (S107).

Next, the normal value is calculated by dividing the difference value by the average value of the absolute values (S108).

At this time, in the present invention, since two or more vibration displacement sensors are used for vibration analysis, a normal value of the output voltage from a sensor at another position is obtained to calculate a difference value between the normal values (S109).

Next, the phase difference is calculated from an average of the absolute values of the difference values of the normal values (S110), and when the phase difference is 0 degrees, the translational vibration is performed, and when the phase difference is 180 degrees, the vibrational vibration can be analyzed. (S111).

As described above, the vibration analysis method of the rotating body of the present invention can determine the translationality and rotationality of the rotating body vibration by using the method of calculating the vibration displacement with respect to the vibration including the fine vibration displacement, There is an effect that it is possible to calculate the vibration displacement at any point on the straight line.

The present invention calculates the displacement by using the structural method and the vibration displacement calculation method of the previously applied vibration displacement sensor, in order to understand the overall movement of the rotating body using a plurality of sensors as well as vibration displacement from the sensor signal between the vibration Add phase difference to understand the movement of the rotor.

1 is an exemplary view showing a schematic configuration of a general vibration displacement calculation system.

FIG. 2 is a circuit diagram showing a schematic circuit configuration of a light receiving portion in FIG.

3 is an exemplary view for explaining a vibration displacement calculation process at each sensor position by the present invention.

Figure 4 is an exemplary view showing a vibration state of the rotating body which can be analyzed by the present invention.

5 is a flow chart showing a vibration analysis method of the rotating body according to the present invention.

Claims (6)

In the method of analyzing the vibration caused by the rotation of the rotating body using two or more vibration displacement sensor, Analyzing the phase difference of each vibration displacement sensor; If the analyzed phase difference is 180 degrees, determining that the rotating body in which the two vibration sensors are positioned performs rotational vibration; And if the analyzed phase difference is 0 degrees, determining that the rotating body in which the two vibration sensors are positioned performs translational vibration. According to claim 1, wherein the rotating body is a part of the body is fixed by a device that is elastic, such as a spring, the two vibration displacement sensors are installed in parallel to the axis of rotation or the angle with the axis of rotation is not large. Method of vibration analysis of a rotating body. The vibration analysis method according to claim 1 or 2, further comprising calculating a normal value for the output voltage from each vibration displacement sensor for detecting the phase difference. 4. The light emitting device of claim 3, wherein the light emitting part spaced apart from the mirror attached to the vibrating body by a predetermined distance for calculating the normal value irradiates light toward a mirror which vibrates together with the vibration of the vibrating body. Step; and A second step of receiving a light reflected by the vibrating mirror in parallel with the light emitting part and receiving a light output part to generate a predetermined output voltage (first output voltage) according to the received light amount; A third step of detecting an output voltage (second output voltage) from which noise is removed from the output voltage and a first output voltage for a predetermined set period and calculating an average voltage based on the average value; Calculating a normal value by a fourth step of calculating a difference value between the second output voltage and the average voltage, calculating an average value for the absolute value of the difference value, and dividing the difference value by the average value of the absolute value. Vibration analysis method of a rotating body characterized in that. The vibration analysis method of claim 4, wherein the normal value is calculated for all two or more vibration displacement sensors installed for vibration analysis. The method of claim 5, further comprising calculating a difference value with respect to a normal value calculated from each of the vibration displacement sensors, and calculating a phase difference from an average of absolute values of the difference value of the normal value. Method of vibration analysis of a rotating body.