CN115046625A - Low-frequency weak vibration signal detection system - Google Patents
Low-frequency weak vibration signal detection system Download PDFInfo
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- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
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- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
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Abstract
The invention discloses a low-frequency weak vibration signal detection system which comprises a measurement unit, wherein the measurement unit comprises an alternating current coupling module, a gain adjustment module, an LPF (low pass filter) module, an ADC (analog-to-digital converter) acquisition module, an MCU (micro control unit) control module and a constant current module which are sequentially connected in series to form a loop; the gain adjusting module is connected with the MCU control module; and the alternating current coupling module is connected with the constant current module, and one end of the alternating current coupling module is connected with the ICP sensor. The system can flexibly adjust output excitation current to match the characteristics of an external sensor and adapt to sensors in different application scenes. The output current can be corrected through the feedback unit; and by adopting a gain adjustable design, the range of the effective measurement signal is flexibly adjusted to be matched with the measurement range of the ADC. Compared with a conventional ICP signal acquisition circuit, the measurement precision is greatly improved. Is worthy of large-area popularization and application.
Description
Technical Field
The invention relates to the technical field of signal detection, in particular to a high-precision low-noise low-frequency weak vibration signal detection system with adjustable constant current output excitation current and adjustable gain.
Background
The method of using an acceleration sensor to identify the operation state of an engineering site or equipment and detect faults is common, and piezoelectric acceleration is one of the most widely used methods. The ICP piezoelectric acceleration transducer is a novel transducer for vibration and noise monitoring, an IC amplifier is arranged in the ICP piezoelectric acceleration transducer, compared with a traditional acceleration transducer, a charge amplifier needs to be additionally used, the use complexity is greatly reduced, and the ICP piezoelectric acceleration transducer is particularly suitable for online detection and field monitoring.
An ICP sensor signal measurement circuit in the prior art has an overall structure as shown in fig. 5, and in an ICP signal acquisition circuit, a constant current power supply module mainly provides an excitation current, generally a direct current signal, required for normal operation of the ICP sensor. The coupling connection mainly refers to a mode adopted by the acquisition circuit and the ICP signal connection, and is usually alternating current coupling. The amplifying circuit is used for amplifying the acquired signal so as to match the measuring range of the ADC in the later stage. The filter circuit is used for filtering out-of-band noise in the sensor signal, so that the measurement accuracy is further improved. The control core is mainly used for acquiring and processing sensor signals.
The constant current power supply module of the ICP signal detection circuit in the prior art is usually implemented by a fixed power supply 24V power supply and a discrete device or implemented by an operational amplifier such as LM334, etc., and generates an unadjustable constant direct current, and the form of the constant current circuit is as shown in fig. 6.
Therefore, in the constant current module design of the ICP signal detection circuit in the prior art, a fixed output excitation current is usually adopted to drive an external sensor, and in the case of a high-amplitude or high-frequency vibration scene, the excitation currents of the sensors are different, and the response characteristics of the sensors to the excitation currents of different magnitudes are different, and the unadjustable constant current value is often difficult to match the optimal response characteristic of the sensor, so that a high-precision measurement result cannot be obtained; meanwhile, in long-term application, temperature drift or time drift is inconvenient to correct.
Disclosure of Invention
The invention provides a low-frequency weak vibration signal detection system. The gain-adjustable high-precision low-noise ICP signal detection system has the advantages of adjustable constant-current output excitation current and adjustable gain. The method can be used for measuring signals of acceleration sensors for monitoring vibration states of ship stern parts, rotating shafts and other parts so as to obtain the running conditions and health states of the parts.
The invention provides the following scheme:
a low frequency weak vibration signal detection system, comprising:
the device comprises a measuring unit, a control unit and a control unit, wherein the measuring unit comprises an alternating current coupling module, a gain adjusting module, an LPF module, an ADC (analog to digital converter) acquisition module, an MCU (micro control unit) control module and a constant current module which are sequentially connected in series to form a loop; the gain adjusting module is connected with the MCU control module; the alternating current coupling module is connected with the constant current module, and one end of the alternating current coupling module is connected with the ICP sensor;
the constant current module is used for generating adjustable current; the MCU control module is used for controlling the constant current module to generate a target excitation current, and the target excitation current is used for matching the optimal response characteristic of the ICP sensor; the gain adjustment module is used for adjusting the range of the effective measurement signal so as to be matched with the measurement range of the ADC acquisition module.
Preferably: the constant current module comprises a digital-to-analog converter DAC, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a rheostat RS, a first operational amplifier U1 and a second operational amplifier U2; the digital-to-analog converter DAC is connected with the MCU control module through an SPI bus; one end of the first resistor R1 is connected with the digital-to-analog converter DAC, and the other end of the first resistor R1 is connected with the third resistor R3 and the first operational amplifier U1; one end of the second resistor R is respectively connected with the fourth resistor R4 and the first operational amplifier U1, and one end of the third resistor R3, which is far away from the first resistor R1, is connected with the second operational amplifier U2; the rheostat RS is respectively connected with the first operational amplifier U1 and the second operational amplifier U2, and one end, far away from the second resistor, of the fourth resistor is connected between the first operational amplifier U1 and the rheostat RS.
Preferably: the first operational amplifier U1 and the second operational amplifier U2 are both 24V power supply precision low-offset operational amplifiers, and the selection type is SGM 8249-1.
Preferably: the first resistor R1 is equal to the third resistor R3, and the second resistor R2 is equal to the fourth resistor R4.
Preferably: the gain adjusting module comprises a compensation resistor RC, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a third operational amplifier U3 and an analog switch U4;
the compensation resistor RC and the fifth resistor R5 are connected to the third operational amplifier U3 in a parallel manner, and one end, away from the third operational amplifier U3, of the fifth resistor R5 is used for being connected with the alternating current coupling module; the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 are connected to the analog switch U4 in parallel; one ends of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10, which are far away from the analog switch U4, are connected between the fifth resistor and the third operational amplifier U3; the analog switch U4 is connected with the MCU control module.
Preferably: the compensation resistor RC and the seventh resistor R7 are both equal in value to the fifth resistor R5, the sixth resistor R6 is 0.5 times the fifth resistor R5, the eighth resistor R8 is 2 times the fifth resistor R5, the ninth resistor R9 is 5 times the fifth resistor R5, and the tenth resistor R10 is 10 times the fifth resistor R5.
Preferably: the LPF module comprises an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a second capacitor C2, a fourth operational amplifier U5 and a fifth operational amplifier U6; the eleventh resistor R11 and the second capacitor C2 are both connected with the fourth operational amplifier U5 to form an LPF filter; the twelfth resistor R12 is respectively connected with the fourth operational amplifier U5 and the fifth operational amplifier U6; the thirteenth resistor R13 is connected with the fifth operational amplifier U6;
wherein, the cut-off frequency Vf of the LPF filter is 1/2 pi R11C 2; the twelfth resistor R12 and the thirteenth resistor R13 have the same value, and the twelfth resistor R12, the thirteenth resistor R13 and the fifth operational amplifier U6 jointly form an inverting proportional amplifier with the proportion of 1.
Preferably: the alternating current coupling module comprises a first capacitor C1, and the value C1 of the first capacitor C1 is 0.1 mu F/50V; the ADC acquisition module comprises a HWD7710 chip; the MCU control module comprises a stm32f429 chip.
Preferably: the feedback unit comprises a detection resistor R0 and an output detection module, the detection resistor R0 is connected between the constant current module and the alternating current coupling module in series, and the output detection module is respectively connected with the detection resistor R0 and the ADC acquisition module;
the feedback unit is used for acquiring output sampling excitation current, and the ADC acquisition module is used for outputting a detection feedback loop value according to the sampling excitation current, so that the MCU control module adjusts the constant current module to output the target excitation current according to the detection feedback loop value.
Preferably: the detection resistor R0 value R0 is 1 omega/5 ppm/0.05%; the output detection module comprises an instrument operational amplifier selection SGM620, and the instrument operational amplifier is used for converting differential voltage at two ends of the detection resistor R0 into single-ended voltage to be input into the ADC acquisition module.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
according to the low-frequency weak vibration signal detection system provided by the embodiment of the application, the output excitation current can be flexibly adjusted to match the characteristics of an external sensor, so that the system is suitable for sensors in different application scenes. The output current can be corrected through the feedback unit; and by adopting a gain adjustable design, the range of the effective measurement signal is flexibly adjusted to be matched with the measurement range of the ADC. Compared with a conventional ICP signal acquisition circuit, the measurement precision is greatly improved. Is worthy of large-area popularization and application.
Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
Fig. 1 is a detection schematic diagram of a low-frequency weak vibration signal detection system according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of a constant current module according to an embodiment of the present invention;
FIG. 3 is a circuit schematic of a gain adjustment module provided by an embodiment of the present invention;
FIG. 4 is a circuit schematic diagram of an LPF module provided by an embodiment of the invention;
FIG. 5 is a schematic diagram of a prior art ICP signal measurement circuit configuration;
fig. 6 is a schematic circuit diagram of a constant current module of an ICP acquisition circuit in the prior art.
In the figure: the device comprises a measuring unit 1, an alternating current coupling module 11, a gain adjusting module 12, an LPF module 13, an ADC acquisition module 14, an MCU control module 15, a constant current module 16, a detection resistor R017, an output detection module 18 and an ICP sensor 19.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments that can be derived by one of ordinary skill in the art from the embodiments given herein are intended to be within the scope of the present invention.
Referring to fig. 1, a system for detecting a low-frequency weak vibration signal according to an embodiment of the present invention, as shown in fig. 1, may include:
the measurement device comprises a measurement unit 1, a gain adjustment module 12, an LPF module 13, an ADC acquisition module 14, an MCU control module 15 and a constant current module 16, wherein the measurement unit comprises an alternating current coupling module 11, the gain adjustment module 12, the LPF module 13, the ADC acquisition module 14, the MCU control module 15 and the constant current module 16 which are sequentially connected in series to form a loop; the gain adjusting module 12 is connected with the MCU control module 15; the alternating current coupling module 11 is connected with the constant current module 16, and one end of the alternating current coupling module is used for being connected with an ICP sensor 19;
the constant current module 16 is used for generating adjustable current; the MCU control module 15 is used for controlling the constant current module 16 to generate a target excitation current, and the target excitation current is used for matching the optimal response characteristic of the ICP sensor 19; the gain adjustment module 12 is used to adjust the range of the effective measurement signal to match the measurement range of the ADC acquisition module 14.
According to the low-frequency weak vibration signal detection system provided by the embodiment of the application, the constant current module adopts a mode that the output excitation current is adjustable, and when the high-amplitude or high-frequency vibration scene is faced, the MCU control module can control the constant current module to output the excitation current which is used for being matched with the optimal response characteristic of the ICP sensor according to the difference of the excitation currents of the sensors and the difference of the response characteristics of the sensors to the excitation currents with different sizes. The method is used for matching the optimal response characteristic of the sensor to obtain a high-precision measurement result.
The constant current module provided by the embodiment of the application adopts a DAC (digital-to-analog converter) and Howland current source design to generate adjustable current. Specifically, as shown in fig. 2, the constant current module 16 includes a digital-to-analog converter DAC, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a varistor RS, a first operational amplifier U1, and a second operational amplifier U2; the digital-to-analog converter DAC is connected with the MCU control module through an SPI bus; one end of the first resistor R1 is connected with the digital-to-analog converter DAC, and the other end of the first resistor R1 is connected with the third resistor R3 and the first operational amplifier U1; one end of the second resistor R is respectively connected with the fourth resistor R4 and the first operational amplifier U1, and one end of the third resistor R3, which is far away from the first resistor R1, is connected with the second operational amplifier U2; the rheostat RS is respectively connected with the first operational amplifier U1 and the second operational amplifier U2, and one end, far away from the second resistor, of the fourth resistor is connected between the first operational amplifier U1 and the rheostat RS. Further, the first operational amplifier U1 and the second operational amplifier U2 are both 24V power supply precision low offset operational amplifiers, and the selection type is SGM 8249-1. The first resistor R1 is equal to the third resistor R3, and the second resistor R2 is equal to the fourth resistor R4.
The ADC acquisition module can acquire a main measurement signal and output a detection feedback loop value; the digital-to-analog converter DAC is communicated with the control core MCU through the SPI, and the MCU controls the DAC to output voltage Vo; u1 and U2 are both 24V power supply precision low-offset operational amplifiers, and the selection type is SGM 8249-1; selecting R1 ═ R3 and R2 ═ R4, namely obtaining voltage V (RS) at two ends of RS, (Vout 1-Vf); according to the negative feedback principle and the virtual short characteristic of the operational amplifier, Vo is Vout 1-Vf; the voltage at two ends of the obtained RS is only directly related to Vo, and the current passing through the RS is Iout Vo/RS by controlling Vo through the MCU.
As shown in fig. 3, the gain adjustment module 12 provided in the embodiment of the present application includes a compensation resistor RC, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a third operational amplifier U3, and an analog switch U4;
the compensation resistor RC and the fifth resistor R5 are connected to the third operational amplifier U3 in a parallel manner, and one end, away from the third operational amplifier U3, of the fifth resistor R5 is used for being connected with the alternating current coupling module; the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 are connected to the analog switch U4 in parallel; one ends of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10, which are far away from the analog switch U4, are connected between the fifth resistor and the third operational amplifier U3; the analog switch U4 is connected with the MCU control module.
Further, the compensation resistor RC and the seventh resistor R7 are both equal to the fifth resistor R5, the sixth resistor R6 is 0.5 times the fifth resistor R5, the eighth resistor R8 is 2 times the fifth resistor R5, the ninth resistor R9 is 5 times the fifth resistor R5, and the tenth resistor R10 is 10 times the fifth resistor R5.
Vin is the output voltage of the capacitor C1. And Rc is the same as R5 in value of compensation resistance. R6 ═ 0.5 × R5, R7 ═ R5, R8 ═ 2 × R5, R9 ═ 5R5, and R10 ═ 10 × R5. Gain adjustment the MCU controls the analog switch U4 to gate any channel to get the corresponding gain. The gain adjusting module can set gains of 0.5, 1, 2, 5 and 10 times, and is realized by an operational amplifier, an analog switch and a high-precision resistor;
as shown in fig. 4, the LPF module 13 according to the embodiment of the present application includes an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a second capacitor C2, a fourth operational amplifier U5, and a fifth operational amplifier U6; the eleventh resistor R11 and the second capacitor C2 are both connected with the fourth operational amplifier U5 to form an LPF filter; the twelfth resistor R12 is respectively connected with the fourth operational amplifier U5 and the fifth operational amplifier U6; the thirteenth resistor R13 is connected with the fifth operational amplifier U6;
wherein, the cut-off frequency Vf of the LPF filter is 1/2 pi R11C 2; the twelfth resistor R12 and the thirteenth resistor R13 have the same value, and the twelfth resistor R12, the thirteenth resistor R13 and the fifth operational amplifier U6 jointly form an inverting proportional amplifier with the proportion of 1.
The LPF module is a first-order low-pass filter; r11, C2 and U5 together form an LPF filter, and the cutoff frequency Vf is 1/2 pi R11 x C2; r12 ═ R13 and U6 together form an inverting proportional amplifier, the ratio is 1; the final output Vlpf is Vin.
The alternating current coupling module 11 includes a first capacitor C1, and a value C1 of the first capacitor C1 is 0.1 μ F/50V; the ADC acquisition module 14 comprises a HWD7710 chip; the MCU control module 15 includes a stm32f429 chip.
The first capacitor C1 is used for ac coupling design, and the value C1 is 0.1 μ F/50V; the ADC acquisition module is realized by using HWD7710, and the ADC has 24-bit resolution and can meet the requirement on use precision. The MCU adopts stm32f429 chip, has low power consumption less than or equal to 0.5W and has the performance of reaching 180MHz dominant frequency.
In order to detect the excitation current in the output current loop, the embodiment of the present application may further provide a feedback unit, where the feedback unit includes a detection resistor R0 and an output detection module, the detection resistor R0 is connected in series between the constant current module and the ac coupling module, and the output detection module is connected to the detection resistor R0 and the ADC acquisition module respectively;
the feedback unit is used for acquiring output sampling excitation current, and the ADC acquisition module is used for outputting a detection feedback loop value according to the sampling excitation current, so that the MCU control module adjusts the constant current module to output the target excitation current according to the detection feedback loop value.
Specifically, the value of the detection resistor R0, R0, is 1 Ω/5 ppm/0.05%; the output detection module comprises an instrument operational amplifier selection SGM620, and the instrument operational amplifier is used for converting differential voltage at two ends of the detection resistor R0 into single-ended voltage to be input into the ADC acquisition module.
The detection resistor R0 is a detection resistor connected in series in an output current loop, and the value R0 is 1 omega/5 ppm/0.05% of the characteristic; the output detection module selects the SGM620 for an instrument operational amplifier and converts the differential voltage at two ends of R0 into a single-ended input ADC.
In a word, the low-frequency weak vibration signal detection system provided by the embodiment of the application can flexibly adjust the output excitation current to match the characteristics of the external sensor, and is suitable for sensors in different application scenes. The output current can be corrected through the feedback unit; and by adopting a gain adjustable design, the range of the effective measurement signal is flexibly adjusted to be matched with the measurement range of the ADC. Compared with a conventional ICP signal acquisition circuit, the measurement precision is greatly improved. Is worthy of large-area popularization and application.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
From the above description of the embodiments, it is clear to those skilled in the art that the present application can be implemented by software plus necessary general hardware platform. Based on such understanding, the technical solutions of the present application may be essentially or partially implemented in the form of a software product, which may be stored in a storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., and includes several instructions for enabling a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the method according to the embodiments or some parts of the embodiments of the present application.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (10)
1. A low-frequency weak vibration signal detection system is characterized by comprising:
the device comprises a measuring unit, a control unit and a control unit, wherein the measuring unit comprises an alternating current coupling module, a gain adjusting module, an LPF module, an ADC (analog to digital converter) acquisition module, an MCU (micro control unit) control module and a constant current module which are sequentially connected in series to form a loop; the gain adjusting module is connected with the MCU control module; the alternating current coupling module is connected with the constant current module, and one end of the alternating current coupling module is connected with the ICP sensor;
the constant current module is used for generating adjustable current; the MCU control module is used for controlling the constant current module to generate a target excitation current, and the target excitation current is used for matching the optimal response characteristic of the ICP sensor; the gain adjustment module is used for adjusting the range of the effective measurement signal so as to be matched with the measurement range of the ADC acquisition module.
2. The system for detecting the low-frequency weak vibration signal according to claim 1, wherein the constant current module comprises a digital-to-analog converter (DAC), a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a rheostat RS, a first operational amplifier (U1) and a second operational amplifier (U2); the digital-to-analog converter DAC is connected with the MCU control module through an SPI bus; one end of the first resistor R1 is connected with the digital-to-analog converter DAC, and the other end of the first resistor R1 is connected with the third resistor R3 and the first operational amplifier U1; one end of the second resistor R is respectively connected with the fourth resistor R4 and the first operational amplifier U1, and one end of the third resistor R3, which is far away from the first resistor R1, is connected with the second operational amplifier U2; the rheostat RS is respectively connected with the first operational amplifier U1 and the second operational amplifier U2, and one end, far away from the second resistor, of the fourth resistor is connected between the first operational amplifier U1 and the rheostat RS.
3. The system for detecting the low-frequency weak vibration signal as claimed in claim 2, wherein the first operational amplifier U1 and the second operational amplifier U2 are both 24V power supply precision low offset operational amplifiers, and the selection type is SGM 8249-1.
4. The system for detecting the low-frequency weak vibration signal of claim 2, wherein the first resistor R1 is equal to the third resistor R3, and the second resistor R2 is equal to the fourth resistor R4.
5. The system for detecting the low-frequency weak vibration signal according to claim 1, wherein the gain adjustment module comprises a compensation resistor RC, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a third operational amplifier U3 and an analog switch U4;
the compensation resistor RC and the fifth resistor R5 are connected to the third operational amplifier U3 in a parallel manner, and one end, away from the third operational amplifier U3, of the fifth resistor R5 is used for being connected with the alternating current coupling module; the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 are connected to the analog switch U4 in parallel; one ends of the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10, which are far away from the analog switch U4, are connected between the fifth resistor and the third operational amplifier U3; the analog switch U4 is connected with the MCU control module.
6. The system for detecting a low-frequency weak vibration signal according to claim 5, wherein the compensation resistor RC and the seventh resistor R7 are both equal to the fifth resistor R5, the sixth resistor R6 is 0.5 times the fifth resistor R5, the eighth resistor R8 is 2 times the fifth resistor R5, the ninth resistor R9 is 5 times the fifth resistor R5, and the tenth resistor R10 is 10 times the fifth resistor R5.
7. The system for detecting the low-frequency weak vibration signal of claim 1, wherein the LPF module comprises an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a second capacitor C2, a fourth operational amplifier U5 and a fifth operational amplifier U6; the eleventh resistor R11 and the second capacitor C2 are both connected with the fourth operational amplifier U5 to form an LPF filter; the twelfth resistor R12 is respectively connected with the fourth operational amplifier U5 and the fifth operational amplifier U6; the thirteenth resistor R13 is connected with the fifth operational amplifier U6;
wherein, the cut-off frequency Vf of the LPF filter is 1/2 pi R11C 2; the twelfth resistor R12 and the thirteenth resistor R13 have the same value, and the twelfth resistor R12, the thirteenth resistor R13 and the fifth operational amplifier U6 jointly form an inverting proportional amplifier with the proportion of 1.
8. The system for detecting the low-frequency weak vibration signal according to claim 1, wherein the ac coupling module includes a first capacitor C1, and a value C1 of the first capacitor C1 is 0.1 μ F/50V; the ADC acquisition module comprises a HWD7710 chip; the MCU control module comprises a stm32f429 chip.
9. The system for detecting the low-frequency weak vibration signal according to claim 1, further comprising a feedback unit, wherein the feedback unit includes a detection resistor R0 and an output detection module, the detection resistor R0 is connected in series between the constant current module and the ac coupling module, and the output detection module is connected to the detection resistor R0 and the ADC collecting module respectively;
the feedback unit is used for acquiring output sampling excitation current, and the ADC acquisition module is used for outputting a detection feedback loop value according to the sampling excitation current, so that the MCU control module adjusts the constant current module to output the target excitation current according to the detection feedback loop value.
10. The system for detecting the low-frequency weak vibration signal according to claim 9, wherein a value R0 of the detection resistor R0 is 1 Ω/5 ppm/0.05%; the output detection module comprises an instrument operational amplifier selection SGM620, and the instrument operational amplifier is used for converting differential voltage at two ends of the detection resistor R0 into single-ended voltage to be input into the ADC acquisition module.
Priority Applications (1)
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