Monitoring equipment

Abstract

The utility model provides monitoring equipment, which comprises a signal conversion module connected with a vibration sensor, the signal conversion module comprises a U1 multiplier and a U2 voltage comparator, the vibration sensor is connected with a first pin and a third pin of the U1 multiplier, a seventh pin of the U1 multiplier is connected with an in-phase input end of the U2 voltage comparator, and a seventh pin of the U2 voltage comparator is connected with a fourth pin of the U1 multiplier. The inverting input end of the U2 voltage comparator is connected with a threshold voltage Vt, the output end of the U2 voltage comparator is electrically connected with the analog-to-digital converter through the U3 digital frequency synthesizer, the analog-to-digital converter is electrically connected with the microcontroller, and the microcontroller is electrically connected with the U3 digital frequency synthesizer. Through the U1 multiplier, the U2 voltage comparator and the U3 digital frequency synthesizer, conversion from a non-stationary original signal to a variance stationary signal is realized, the non-stationary original signal does not need to be processed and analyzed through other processing methods again, and the complexity of signal analysis is reduced.

Description

Technical Field

[0001] This utility model relates to the field of engineering measurement technology, and in particular to a monitoring device. Background Technology

[0002] In structural safety monitoring, the measurement and analysis of dynamic signals, including spectrum analysis, is a commonly used method. By analyzing the spectrum of the original signal, the frequency domain characteristics of the structure's vibration can be seen intuitively.

[0003] However, after excitation of the structure, a damped free vibration signal (periodic invariance) is generally generated. In the frequency domain, this signal will produce a phenomenon similar to narrowband modulation (such as common amplitude modulation signals) near the natural frequency, that is, it generates a non-stationary dynamic signal.

[0004] Since the statistical characteristics of non-stationary dynamic signals are time-dependent, processing non-stationary dynamic signals requires simultaneous analysis of the time domain and frequency domain. For example, non-stationary signals can be processed using methods such as short-time Fourier transform, wavelet transform, and Hilbert-Huang transform before analysis. However, this processing method increases the complexity of signal analysis. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a monitoring device that aims to solve the technical problem that, due to the characteristics of non-stationary dynamic signals, it is necessary to process the non-stationary dynamic signals through algorithms before analysis, which increases the complexity of the analysis.

[0006] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0007] A monitoring device includes a signal conversion module connected to a vibration sensor. The signal conversion module converts the non-stationary raw signal acquired by the vibration sensor into a standard square wave signal. The signal conversion module includes a U1 multiplier and a U2 voltage comparator. The vibration sensor is connected to pins 1 and 3 of the U1 multiplier. Pin 7 of the U1 multiplier is connected to the non-inverting input of the U2 voltage comparator. The inverting input of the U2 voltage comparator is connected to a threshold voltage Vt. The output of the U2 voltage comparator is electrically connected to an analog-to-digital converter (ADC) via a U3 digital frequency synthesizer. The ADC is electrically connected to a microcontroller. The microcontroller is electrically connected to the U3 digital frequency synthesizer to write a fixed counting step parameter into the U3 digital frequency synthesizer.

[0008] Compared with the prior art, the beneficial effects of this utility model are as follows: After acquiring the non-stationary original signal, the frequency of the signal is multiplied by the U1 multiplier, and the bipolar signal is conditioned into a unipolar sine wave signal with damped attenuation, which is then transmitted to the U2 voltage comparator. The U2 voltage comparator shapes the unipolar sine wave signal with damped attenuation into a square wave signal, which is then transmitted to the U3 digital frequency synthesizer. Utilizing the function of the U3 digital frequency synthesizer in outputting a stable sine wave signal, the input clock signal of the U3 digital frequency synthesizer is replaced with a square wave signal, and a fixed counting step parameter is written through the microcontroller to realize the restoration of the square wave signal into a variance-stationary signal. That is, by setting the corresponding circuit, the conversion of the non-stationary original signal into a variance-stationary signal is realized, without the need for further processing and analysis of the non-stationary original signal through other processing methods, thus reducing the complexity of signal analysis.

[0009] Furthermore, a resistor R3 is provided between the 7th pin of the U1 multiplier and the non-inverting input of the U2 voltage comparator, a resistor R1 is provided between the non-inverting input of the U2 voltage comparator and the output of the U2 voltage comparator, and the output of the U2 voltage comparator is electrically connected to a resistor R2.

[0010] Furthermore, a signal processing module is provided between the vibration sensor and the signal conversion module. The signal processing module is used to preprocess the non-stationary original signal. The signal processing module includes a signal amplification circuit and a filtering circuit. The vibration sensor is electrically connected to the signal amplification circuit, the signal amplification circuit is electrically connected to the filtering circuit, and the filtering circuit is electrically connected to the first and third pins of the U1 multiplier.

[0011] Furthermore, a low-pass filter is provided between the U3 digital frequency synthesizer and the analog-to-digital converter.

[0012] Furthermore, the low-pass filter includes amplifier U4, capacitor C4, and capacitor C10. Pin 10 of the digital frequency synthesizer U3 is electrically connected to the non-inverting input of amplifier U4. Resistors R4 and R5 are disposed between pin 10 of the digital frequency synthesizer U3 and the non-inverting input of amplifier U4. One end of capacitor C4 is connected between resistors R4 and R5, and the other end of capacitor C4 is connected to the inverting input of amplifier U4. Capacitor C10 is disposed between resistor R5 and the non-inverting input of amplifier U4. The output of amplifier U4 is electrically connected to the analog-to-digital converter.

[0013] Furthermore, the filtering circuit is a tetravalent active low-pass filter.

[0014] Furthermore, a signal gate is provided between the U2 voltage comparator and the U3 digital frequency synthesizer, and a signal validity judgment circuit is provided between the filter circuit and the signal gate. The signal validity judgment circuit is used to compare the envelope signal of the preprocessed non-stationary original signal with the reference voltage value to control the opening and closing of the signal gate.

[0015] Furthermore, the signal validity determination circuit is electrically connected to the microcontroller. Attached Figure Description

[0016] Figure 1 This is a structural block diagram of the monitoring device in an embodiment of the present utility model;

[0017] Figure 2 This is a circuit diagram showing the connection of the U1 multiplier and the U2 voltage comparator in the monitoring device of this utility model embodiment;

[0018] Figure 3 This is a circuit diagram showing the connection of the U3 digital frequency synthesizer and low-pass filter in the monitoring device of this utility model embodiment;

[0019] Explanation of key component symbols:

[0020] 1. Signal amplification circuit; 2. Filtering circuit; 3. U1 multiplier; 4. U2 voltage comparator; 5. Signal gate; 6. U3 digital frequency synthesizer; 7. Low-pass filter; 8. Signal validity judgment circuit; 9. Analog-to-digital converter; 10. Microcontroller.

[0021] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this utility model. Detailed Implementation

[0022] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this utility model will be more thorough and complete.

[0023] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] Please see Figures 1 to 3 The monitoring device in this embodiment of the utility model includes a signal conversion module connected to a vibration sensor. The vibration sensor is used to collect vibration signals generated after the structure is excited. The vibration signal is a non-stationary original signal. The signal conversion module is used to convert the non-stationary original signal collected by the vibration sensor into a standard square wave signal.

[0026] Specifically, the signal conversion module includes a U1 multiplier 3 and a U2 voltage comparator 4. The vibration sensor is connected to the first and third pins of the U1 multiplier 3. The seventh pin of the U1 multiplier 3 is connected to the non-inverting input of the U2 voltage comparator 4. The inverting input of the U2 voltage comparator 4 is connected to the threshold voltage Vt. The output of the U2 voltage comparator 4 is electrically connected to the analog-to-digital converter 9 through the U3 digital frequency synthesizer 6. When the non-stationary original signal enters the U1 multiplier 3, the U1 multiplier 3 performs a square operation on the signal. The squared signal contains a second harmonic component and a DC component of the non-stationary original signal. At the same time, the bipolar signal is conditioned into a unipolar signal so that when the subsequent signal enters the U3 digital frequency synthesizer 6, it satisfies the sampling theorem: the maximum frequency of the output signal is half the frequency of the input signal. Therefore, the frequency multiplication process can compensate for the frequency reduction of the signal after entering the U3 digital frequency synthesizer 6. The threshold voltage Vt of the U2 voltage comparator 4 is 50mV to 100mV. The U2 voltage comparator 4 is used to shape the squared signal into a square wave signal, which is used as the input signal of the U3 digital frequency synthesizer 6.

[0027] A resistor R3 is provided between pin 7 of the U1 multiplier 3 and the non-inverting input of the U2 voltage comparator 4. A resistor R1 is provided between the non-inverting input and the output of the U2 voltage comparator 4. The output of the U2 voltage comparator 4 is electrically connected to a resistor R2. The U2 voltage comparator 4, resistors R1, R2, and R3 form a comparator with hysteresis, which can effectively filter out minor interference near the threshold. Although the comparator with hysteresis has a certain delay in the input signal, spectrum analysis mainly considers the periodicity of the signal. Therefore, the hysteresis function has no impact on the accuracy of frequency measurement. The analog-to-digital converter 9 is electrically connected to the microcontroller 10, and the microcontroller 10 is electrically connected to the U3 digital frequency synthesizer 6 to write fixed counting step parameters into the U3 digital frequency synthesizer 6. After acquiring the non-stationary original signal, it undergoes frequency multiplication by the U1 multiplier 3, and the bipolar signal is conditioned into a unipolar sine wave signal with damped attenuation. This signal is then transmitted to the U2 voltage comparator 4. The U2 voltage comparator 4 shapes the unipolar sine wave signal with damped attenuation into a square wave signal, which is then transmitted to the U3 digital frequency synthesizer 6. Utilizing the U3 digital frequency synthesizer 6's ability to output a stable sine wave signal, the input clock signal of the U3 digital frequency synthesizer 6 is replaced with a square wave signal. A fixed counting step parameter is written into the microcontroller 10, thereby restoring the square wave signal to a variance-stationary signal. In other words, by setting up appropriate circuits, the non-stationary original signal is converted into a variance-stationary signal, eliminating the need for further processing and analysis of the non-stationary original signal, thus reducing the complexity of signal analysis.

[0028] The U3 digital frequency synthesizer 6 consists of a phase accumulator, a phase amplitude table, and a digital-to-analog converter. As a commonly used frequency synthesis method, it generates periodic waveforms, producing sine waves, triangle waves, and square waves ranging from low frequencies to hundreds of MHz. The data output from the phase accumulator is used as the phase sampling address of the waveform memory. This allows the waveform sample value (binary code) stored in the waveform memory (sine wave) to be retrieved via a lookup table, completing the phase-to-amplitude conversion.

[0029] A signal processing module is provided between the vibration sensor and the signal conversion module. This module preprocesses the non-stationary raw signal and includes a signal amplification circuit 1 and a filter circuit 2. The vibration sensor is electrically connected to the signal amplification circuit 1, which in turn is electrically connected to the filter circuit 2. The filter circuit 2 is electrically connected to pins 1 and 3 of the U1 multiplier 3. The signal amplification circuit 1 amplifies the non-stationary raw signal to improve its signal-to-noise ratio. Depending on the signal chain type, single-ended signal conditioning can use the single-ended signal amplification circuit 1, such as an in-phase amplifier, while differential signal chains can use an instrumentation amplifier. By using the filter circuit 2, aliasing signals can be suppressed to meet sampling requirements, and interference and noise outside the signal bandwidth can be filtered out, such as high-frequency external electromagnetic interference and unwanted vibration interference signals. In this embodiment, the filter circuit 2 is a fourth-order active low-pass filter. The passband cutoff frequency of the fourth-order active low-pass filter is the upper limit of the frequency of the analyzed signal. Its topology adopts an SK form with a gain of 1, offering advantages such as high accuracy and reduced circuit elements.

[0030] A low-pass filter 7 is provided between the U3 digital frequency synthesizer 6 and the analog-to-digital converter 9. Since the output of the U3 digital frequency synthesizer 6 is a signal sampled according to the Nyquist sampling principle, the frequency of the output signal is equivalent to the signal to be sampled, while the frequency of the input signal is equivalent to the sampling frequency. Therefore, its output spectrum contains the fundamental frequency and aliased signals (images). By setting the low-pass filter 7, unwanted high-frequency spurious signals and harmonic signals can be filtered out so as to output a sine wave signal with a pure spectrum.

[0031] The low-pass filter 7 includes an amplifier U4, a capacitor C4, and a capacitor C10. Pin 10 (VOUT) of the digital frequency synthesizer U3 is electrically connected to the non-inverting input of the amplifier U4. Resistors R4 and R5 are provided between pin 10 of the digital frequency synthesizer U3 and the non-inverting input of the amplifier U4. One end of the capacitor C4 is connected between resistors R4 and R5, and the other end of the capacitor C4 is connected to the inverting input of the amplifier U4. Capacitor C10 is provided between resistor R5 and the non-inverting input of the amplifier U4. The output of the amplifier U4 is electrically connected to the analog-to-digital converter 9. The microcontroller 10 is electrically connected to pins 6 (DAT), 7 (CLK), and 8 (SYNC) of the digital frequency synthesizer U3 to complete the configuration of the fixed counting step parameters.

[0032] Furthermore, a signal gate 5 is provided between the U2 voltage comparator 4 and the U3 digital frequency synthesizer 6, and a signal validity judgment circuit 8 is provided between the filter circuit 2 and the signal gate 5. The signal validity judgment circuit 8 is used to compare the envelope signal of the preprocessed non-stationary original signal with a reference voltage value to control the opening and closing of the signal gate 5. The signal validity judgment circuit 8 includes a validity judgment voltage comparator, which completes the validity judgment by selecting the voltage value of the valid threshold voltage connected to it as the reference voltage value. When the envelope signal is higher than the reference voltage value, a high level is output to drive the signal gate 5 to open; when the envelope signal is lower than the reference voltage value, a low level is output to drive the signal gate 5 to close. At the same time, the signal validity judgment circuit 8 is electrically connected to the microcontroller 10, so that when the signal validity judgment circuit 8 outputs a high level to drive the signal gate 5 to open, a signal is synchronously sent to the microcontroller 10. The microcontroller 10 controls the analog-to-digital converter 9 to sample the signal.

[0033] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0034] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A monitoring device, characterized in that The signal conversion module connected with the vibration sensor is used for converting the non-stationary original signal collected by the vibration sensor into a standard square wave signal, the signal conversion module comprises a U1 multiplier and a U2 voltage comparator, the vibration sensor is connected with the first pin and the third pin of the U1 multiplier, the seventh pin of the U1 multiplier is connected with the non-inverted input end of the U2 voltage comparator, the inverted input end of the U2 voltage comparator is connected with a threshold voltage Vt, the output end of the U2 voltage comparator is connected with a U3 digital frequency synthesizer and an analog-digital converter, the analog-digital converter is connected with a microcontroller, and the microcontroller is connected with the U3 digital frequency synthesizer to write a fixed counting step parameter into the U3 digital frequency synthesizer.

2. The monitoring device of claim 1, wherein, A resistor R3 is arranged between the seventh pin of the U1 multiplier and the non-inverted input end of the U2 voltage comparator, a resistor R1 is arranged between the non-inverted input end of the U2 voltage comparator and the output end of the U2 voltage comparator, and the output end of the U2 voltage comparator is connected with a resistor R2.

3. The monitoring device of claim 1, wherein, A signal processing module is arranged between the vibration sensor and the signal conversion module, the signal processing module is used for pre-processing the non-stationary original signal, the signal processing module comprises a signal amplification circuit and a filter circuit, the vibration sensor is connected with the signal amplification circuit, the signal amplification circuit is connected with the filter circuit, and the filter circuit is connected with the first pin and the third pin of the U1 multiplier.

4. The monitoring device of claim 1, wherein, A low-pass filter is arranged between the U3 digital frequency synthesizer and the analog-digital converter.

5. The monitoring device of claim 4, wherein, The low-pass filter comprises an amplifier U4, a capacitor C4 and a capacitor C10, the tenth pin of the U3 digital frequency synthesizer is connected with the non-inverted input end of the amplifier U4, a resistor R4 and a resistor R5 are arranged between the tenth pin of the U3 digital frequency synthesizer and the non-inverted input end of the amplifier U4, one end of the capacitor C4 is connected between the resistor R4 and the resistor R5, the other end of the capacitor C4 is connected with the inverted input end of the amplifier U4, the capacitor C10 is arranged between the resistor R5 and the non-inverted input end of the amplifier U4, and the output end of the amplifier U4 is connected with the analog-digital converter.

6. The monitoring device of claim 3, wherein, The filter circuit is a four-valence active low-pass filter.

7. The monitoring device of claim 3, wherein, A signal gate is arranged between the U2 voltage comparator and the U3 digital frequency synthesizer, a signal validity judgment circuit is arranged between the filter circuit and the signal gate, and the signal validity judgment circuit is used for comparing the envelope signal of the pre-processed non-stationary original signal with a reference voltage value to control the opening and closing of the signal gate.

8. The monitoring device of claim 7, wherein, The signal validity judgment circuit is connected with the microcontroller.

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