Hysteretic compensation system and method for low-frequency compensation of magnetoelectric vibration sensor

Abstract

The invention discloses a hysteresis compensation system and method for low-frequency compensation of a magnetoelectric vibration sensor. The compensation system comprises a difference to single-end circuit, a second-order lag compensation circuit, a single-chip microcomputer, an ADC conversion module, a first-order high-pass filtering module and a second-order low-pass filtering module which are sequentially connected with the magnetoelectric vibration sensor. The differential-to-single-end conversion circuit receives voltage signals output by the magnetoelectric vibration sensor and converts the voltage signals into single-end electric signals, the second-order lag compensation circuit receives the single-end electric signals of the differential-to-single-end conversion circuit for low-frequency compensation, the single-chip microcomputer receives low-frequency compensation signals, the ADC conversion module converts the low-frequency compensation electric signals into digital signals, and the digital signals are transmitted to the magnetoelectric vibration sensor. The first-order high-pass filtering module filters noise with the frequency lower than f1 out of the digital signals, and the second-order low-pass filtering module filters noise with the frequency higher than f2 out of the digital signals output by the first-order high-pass filtering module. According to the invention, the amplitude response of the magnetoelectric vibration sensor during low-frequency signal measurement can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor testing, and particularly relates to a hysteresis compensation system and method for low-frequency compensation of a magnetoelectric vibration sensor. Background Art

[0002] A magnetoelectric vibration sensor consists of a mechanical vibration pickup system and an electromagnetic induction system. During monitoring, relative motion occurs between the coil and the permanent magnet inside the sensor, thereby generating an induced electromotive force proportional to the relative motion speed. The magnetoelectric vibration sensor can measure low-frequency or ultra-low-frequency vibration signals, and due to its advantages such as high signal-to-noise ratio, good stability, and large dynamic range, it has been widely used in fields such as seismic observation and ground pulsation observation, structural health monitoring, energy and mining engineering, etc.

[0003] When measuring low-frequency vibrations, if the frequency of the measured signal is lower than the natural frequency of the magnetoelectric vibration velocity sensor, the attenuation trend of the sensor measurement sensitivity is relatively obvious, resulting in problems such as insufficient amplitude response of the sensor output signal, insufficient linearity, and too low signal-to-noise ratio. Limited by mechanical principles, it is difficult to achieve a natural frequency below 1 Hz for a magnetoelectric sensor under limited size conditions, significantly restricting its low-frequency application scenarios. Therefore, it is necessary to dynamically compensate the output signal of the magnetoelectric sensor in the low-frequency band.

[0004] Common compensation methods in the prior art include passive compensation method and zero-pole configuration compensation method.

[0005] The passive compensation method is to connect a capacitor in parallel at the output end to increase the equivalent inertial mass of the magnetoelectric vibration sensor to reduce the natural frequency of the sensor, making the signal change more smoothly in the low-frequency band, and thus improving the sensitivity of the output signal in the low-frequency band. However, this method will reduce the sensitivity in the medium and high-frequency bands, and the parallel capacitor is easily affected by the external environment, resulting in unstable compensation effects.

[0006] The zero-pole configuration compensation method is to improve the low-frequency response characteristics of the sensor through a series correction circuit. The zero point of the transfer function of the correction circuit eliminates the pole point of the transfer function of the original sensor to correct the overall transfer function of the sensor, thereby improving the response characteristics in the low-frequency band of the sensor. However, this method requires measuring the accurate mathematical model of the sensor, and the capacitors sold on the market do not accurately have an error value of 5%, so the parameter debugging steps are relatively cumbersome. Summary of the Invention

[0007] In view of the above existing problems, the present invention proposes a hysteresis compensation system and method for low-frequency compensation of a magnetoelectric vibration sensor, which can improve the amplitude response when the magnetoelectric vibration sensor measures low-frequency signals.

[0008] The above object is achieved by the following technical solutions:

[0009] The present invention first provides a hysteresis compensation system for low-frequency compensation of a magnetoelectric vibration sensor, which includes a differential-to-single-ended circuit, a second-order hysteresis compensation circuit, a single-chip microcomputer, an ADC conversion module, a first-order high-pass filter module, and a second-order low-pass filter module that are sequentially connected to the magnetoelectric vibration sensor.

[0010] Further, the second-order hysteresis compensation circuit is composed of resistors R1, R2, R3, a capacitor C, and an operational amplifier; where R1 and C provide input impedance adjustment to form a first-order hysteresis link; R2 is a phase compensation resistor to adjust the high-frequency response characteristic; R3 is a feedback main resistor that affects the gain; and the operational amplifier provides gain and impedance transformation.

[0011] The single-chip microcomputer is an ATtiny12 single-chip microcomputer.

[0012] The ADC conversion module is built into the single-chip microcomputer;

[0013] The first-order digital high-pass filter module and the second-order low-pass filter module are implemented by the single-chip microcomputer software algorithm.

[0014] The magnetoelectric vibration sensor is a moving-coil velocity sensor;

[0015] The second object of the present invention is to provide a method for low-frequency compensation of a magnetoelectric vibration sensor using the above-mentioned hysteresis compensation system and method for low-frequency compensation of a magnetoelectric vibration sensor. The method includes the following steps:

[0016] S1. Fix the housing of the magnetoelectric vibration sensor on the surface of the object to be measured. When a vibration event occurs to the object to be measured, the vibration frequency is the input signal. The magnetoelectric vibration sensor outputs an electrical signal due to electromagnetic induction. According to the natural frequency ω0, damping ratio ζ, and sensitivity coefficient G in the parameters of the magnetoelectric vibration sensor, and since the magnetoelectric vibration sensor is a second-order damping system, the transfer function G0(s) of the input vibration signal of the sensor and the output voltage signal can be known as:

[0017]

[0018] In the above formula, s is a complex variable used to describe the dynamic characteristics of the system;

[0019] S2. The voltage signal output by the magnetoelectric vibration sensor is converted into a single-ended output electrical signal through the differential-to-single-ended circuit and output to the second-order hysteresis compensation circuit;

[0020] S3. According to the parameters of the electronic components in the second-order hysteresis compensation circuit, three intermediate parameters K, ω1, and ω2 are defined respectively as:

[0021]

[0022] The transfer function G1(s) of the second-order hysteresis compensation circuit can be obtained as:

[0023]

[0024] S4. Connect the second-order lag compensation circuit in series with the sensor, then the transfer function G2(s) of the input vibration signal and the output electrical signal of the system is:

[0025]

[0026] By adjusting the resistance and capacitance values in the second-order lag compensation circuit, making ω2 = ω0, so that the system damping ratio ζ = 1 to reduce the

[0027] order of the transfer function, then Equation (4) can be rewritten as:

[0028]

[0029] S5. It can be seen from Equation (5) that by adjusting the values of resistors R1, R2, and R3, the intermediate parameters K, ω1, and ω2 can be changed, thereby changing the natural frequency of the entire system. The natural frequency of the system after introducing the second-order lag compensation circuit is 1 / n of the original magnetoelectric vibration sensor, then there is:

[0030] The relationship of the intermediate parameters K, ω1, and ω2 at this time is:

[0031]

[0032] Substituting Equation (2) into Equation (7), the numerical relationship of resistors R1, R2, and R3 can be obtained as:

[0033]

[0034] Substituting Equation (2) into Equation (7), the numerical relationship of resistors R1, R2, and R3 can be obtained as:

[0035]

[0036] S6. The sensing signal is input to the single-chip microcomputer through the compensation circuit, converted into a digital signal by the ADC converter, and then passes through a first-order high-pass digital filter module with a cut-off frequency of and a second-order low-pass digital filter module with a cut-off frequency of f2 (200Hz < f2 < 300Hz) to remove the noise in the non-sensing interval. Finally, the signal output by the single-chip microcomputer is the digital signal after low-frequency compensation - filtering.

[0037] S7. The single-chip microcomputer outputs a digital signal processed by low-frequency compensation - filtering.

[0038] Compared with the prior art, the benefits of the present invention are:

[0039] 1. Without changing the internal structure of the magnetoelectric vibration sensor, the present invention reduces the system natural frequency through an external module, thereby improving the sensitivity of the sensor in the low-frequency band.

[0040] 2. This method only improves the sensitivity in the low-frequency band and does not reduce the sensitivity of the magnetoelectric vibration sensor in the medium and high-frequency responses.

[0041] 3. Digital filters are used for signal post-processing, eliminating the need to consider issues such as impedance matching and the accuracy of electronic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic structural diagram of the low-frequency compensation system of the magnetoelectric vibration sensor of the present invention;

[0043] Figure 2 is a flowchart of the low-frequency compensation method of the magnetoelectric vibration sensor of the present invention;

[0044] Figure 3 is a schematic structural diagram of the differential-to-single-ended circuit in the present invention;

[0045] Figure 4 is a schematic structural diagram of the second-order lag compensation circuit in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046] Example 1

[0047] See Figure 1 , the lag compensation system for low-frequency compensation of the magnetoelectric vibration sensor in this embodiment includes a magnetoelectric vibration sensor 1, a differential-to-single-ended conversion circuit 2, a second-order lag compensation circuit 3, a single-chip microcomputer 4, an ADC conversion module 5, a first-order high-pass filter module 6, and a second-order low-pass filter module 7.

[0048] The magnetoelectric vibration sensor 1 is a moving-coil velocity sensor; the single-chip microcomputer 4 is an ATtiny12 single-chip microcomputer; the ADC conversion module 5 is an internal module of the single-chip microcomputer 4; both the first-order high-pass filter module 6 and the second-order low-pass filter module 7 are implemented by the built-in algorithms of the single-chip microcomputer 4.

[0049] The differential-to-single-ended conversion circuit 2 receives the voltage signal output by the magnetoelectric vibration sensor 1 and converts it into a single-ended electrical signal. The second-order lag compensation circuit 3 receives the single-ended electrical signal from the differential-to-single-ended conversion circuit 2 for low-frequency compensation. The single-chip microcomputer 4 receives the low-frequency compensation signal, and the ADC conversion module 5 converts the low-frequency compensation electrical signal into a digital signal. The first-order high-pass filter module 6 filters out the noise with a frequency lower than from the digital signal output by the ADC conversion module 5, and the second-order low-pass filter module 7 filters out the noise with a frequency higher than f2 (200 Hz < f2 < 300 Hz) from the digital signal output by the first-order high-pass filter module 6.

[0050] In this embodiment, the second-order lag compensation circuit is composed of a resistor R1, R2, R3, a capacitor C, and an operational amplifier; the circuit diagram is as Figure 4 shown, where R1 and C provide input impedance adjustment to form a first-order lag link; R2 is a phase compensation resistor to adjust the high-frequency response characteristic; R3 is a feedback main resistor that affects the gain; the operational amplifier provides gain and impedance transformation.

[0051] The first-order digital high-pass filter module and the second-order low-pass filter module are implemented by a single-chip microcomputer software algorithm.

[0052] The magnetoelectric vibration sensor is a moving-coil velocity sensor.

[0053] Embodiment 2:

[0054] This embodiment provides a method for low-frequency compensation of a magnetoelectric vibration sensor using the lag compensation system for low-frequency compensation of the above-mentioned magnetoelectric vibration sensor. The method includes the following steps:

[0055] S1. Fix the housing of the magnetoelectric vibration sensor on the surface of the object to be measured. When a vibration event occurs to the object to be measured, the vibration frequency is the input signal. The magnetoelectric vibration sensor outputs an electrical signal due to electromagnetic induction. According to the natural frequency ω0, damping ratio ζ, and sensitivity coefficient G in the parameters of the magnetoelectric vibration sensor, and the magnetoelectric vibration sensor is a second-order damping system, the transfer function G0(s) of the input vibration signal and the output voltage signal of the sensor can be known as:

[0056]

[0057] In the above formula, s is a complex variable used to describe the dynamic characteristics of the system;

[0058] S2. The voltage signal output by the magnetoelectric vibration sensor is converted into a single-ended output electrical signal through a differential-to-single-ended circuit and output to the second-order lag compensation circuit;

[0059] S3. According to the parameters of the electronic components in the second-order lag compensation circuit, define three intermediate parameters K, ω1, and ω2 respectively as:

[0060]

[0061] The transfer function G1(s) of the second-order lag compensation circuit can be obtained as:

[0062]

[0063] S4. Connect the second-order lag compensation circuit in series with the sensor, then the transfer function G2(s) of the input vibration signal and the output electrical signal of the system is:

[0064]

[0065] By adjusting the resistance and capacitance values in the second-order lag compensation circuit to make ω2 = ω0, so that the system damping ratio ζ = 1 to reduce the order of the system transfer function, then Equation (4) can be rewritten as:

[0066]

[0067] S5. As can be seen from Equation (5), by adjusting the values of resistors R1, R2, and R3, the intermediate parameters K, ω1, and ω2 can be changed, thereby changing the natural frequency of the entire system. The natural frequency of the system after introducing the second-order lag compensation circuit is 1 / n of that of the original magnetoelectric vibration sensor, so there is:

[0068]

[0069] At this time, the relationship between the intermediate parameters K, ω1, and ω2 can be known as:

[0070]

[0071] Substituting Equation (2) into Equation (7), the numerical relationship of resistors R1, R2, and R3 can be obtained as:

[0072]

[0073] S6. The sensing signal is input to the single-chip microcomputer after passing through the compensation circuit, converted into a digital signal by the ADC converter, and then passes through a first-order high-pass digital filter module with a cut-off frequency of and a second-order low-pass digital filter module with a cut-off frequency of f2 (200Hz < f2 < 300Hz) to remove the noise in the non-sensing interval. Finally, the signal output by the single-chip microcomputer is the digital signal after low-frequency compensation - filtering.

[0074] S7. The single-chip microcomputer outputs the digital signal processed by low-frequency compensation - filtering.

Claims

1. A hysteresis compensation system for low-frequency compensation of a magnetoelectric vibration sensor, characterized in that: The low-frequency compensation system of the magnetoelectric vibration sensor comprises a differential to single-ended circuit, a second-order lag compensation circuit, a single-chip microcomputer, an ADC conversion module, a first-order high-pass filter module, and a second-order low-pass filter module which are sequentially connected to the magnetoelectric vibration sensor.

2. The low-frequency compensation system of the magnetoelectric vibration sensor based on hysteresis compensation according to claim 1 is characterized in that: The second-order lag compensation circuit is composed of resistors R1, R2, R3, capacitor C and an operational amplifier; wherein R1 and C provide input impedance adjustment to form a first-order lag link; R2 is a phase compensation resistor to adjust the high-frequency response characteristics; R3 is a feedback main resistor to affect the gain; and the operational amplifier provides gain and impedance transformation.

3. The low-frequency compensation system of a magnetoelectric vibration sensor based on hysteresis compensation according to claim 1 or 2, characterized in that: The single chip microcomputer is an ATtiny12 single chip microcomputer.

4. The low-frequency compensation system of a magnetoelectric vibration sensor based on hysteresis compensation according to claim 1 or 2, characterized in that: The ADC conversion module is built in the single chip microcomputer.

5. The low-frequency compensation system of a magnetoelectric vibration sensor based on hysteresis compensation according to claim 1 or 2, characterized in that: The first-order digital high-pass filter module and the second-order low-pass filter module are implemented by a single-chip microcomputer software algorithm.

6. The low-frequency compensation system of a magnetoelectric vibration sensor based on hysteresis compensation according to claim 1 or 2, characterized in that: The magnetoelectric vibration sensor is a moving coil speed sensor.

7. A method for low-frequency compensation of a magnetoelectric vibration sensor using the hysteresis compensation system for low-frequency compensation of a magnetoelectric vibration sensor according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: S1. Fix the magnetoelectric vibration sensor housing on the surface of the object to be measured. When the object to be measured vibrates, the vibration frequency is the input signal, and the magnetoelectric vibration sensor outputs an electrical signal due to electromagnetic induction. According to the natural frequency ω0, damping ratio ζ and sensitivity coefficient G in the magnetoelectric vibration sensor parameters and the magnetoelectric vibration sensor is a second-order damping system, it can be known that the transfer function G0(s) between the sensor input vibration signal and the output voltage signal is: In the formula, s is a complex variable used to describe the dynamic characteristics of the system; S2. The voltage signal output by the magnetoelectric vibration sensor is converted into a single-ended output electrical signal through a differential to single-ended circuit and output to a second-order lag compensation circuit; S3. According to the parameters of the electronic components in the second-order lag compensation circuit, three intermediate parameters K, ω1, and ω2 are defined as follows: The transfer function G1(s) of the second-order lag compensation circuit is obtained as: S4. Connect the second-order lag compensation circuit in series with the sensor, and the transfer function G2(s) between the input vibration signal and the output electrical signal of the system is: By adjusting the resistance and capacitance values ​​in the second-order lag compensation circuit, setting ω2 = ω0, the system damping ratio ζ = 1 to reduce the order of the system transfer function, then equation (4) can be rewritten as: S5. From formula (5), we can know that by adjusting the values ​​of resistors R1, R2, and R3, we can change the intermediate parameters K, ω1, and ω2, thereby changing the natural frequency of the entire system. The natural frequency of the system after introducing the second-order lag compensation circuit is 1 / n of the original magnetoelectric vibration sensor, so: At this time, the relationship between the intermediate parameters K, ω1, and ω2 is: Substituting formula (2) into formula (7), the numerical relationship between the resistors R1, R2, and R3 is: S6. The sensing signal is input to the single-chip microcomputer after passing through the compensation circuit, converted into a digital signal by the ADC converter, and then passed through a first-order high-pass digital filter module with a cut-off frequency of and a second-order low-pass digital filter module with a cut-off frequency of f2 (200 Hz < f2 < 300 Hz) to remove the noise in the non-sensing interval. Finally, the signal output by the single-chip microcomputer is the digital signal after low-frequency compensation - filtering; S7. The microcontroller outputs a digital signal that has undergone low-frequency compensation and filtering.

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