A weak pressure detection method and system

Abstract

The application discloses a weak pressure detection method and system, which comprises a piezoelectric pressure sensor, a piezoresistive pressure sensor, a piezoelectric pressure sensor charge amplification filter circuit, a piezoresistive pressure sensor full-bridge amplification filter circuit, an analog switch circuit, an ADC conversion circuit and a processor; the piezoelectric pressure sensor charge amplification filter circuit comprises a charge amplification circuit, a follower and an amplification filter circuit; the piezoresistive pressure sensor full-bridge amplification filter circuit comprises a sensor full-bridge circuit and a differential amplification filter circuit; the input end of the analog switch circuit is electrically connected with the output end of the differential amplification filter circuit and the output end of the amplification filter circuit respectively, and the output end of the analog switch circuit is electrically connected with the input end of the processor. The application can adapt to signal frequency, simultaneously cover static and dynamic pressure detection, and realize high-precision weak signal extraction in a strong noise background.

Description

Technical Field

[0001] This invention relates to the field of pressure sensing technology, and in particular to a method and system for detecting weak pressure. Background Technology

[0002] Low-pressure measurement has significant application value in fields such as industrial inspection, environmental monitoring, and biomedicine. Traditional pressure detection systems are mainly divided into two categories: static pressure detection and dynamic pressure detection. Static pressure detection systems typically do not have high requirements for frequency response, while dynamic pressure detection systems need to pay attention to the time-varying characteristics and frequency components of the signal.

[0003] Most existing pressure sensing systems are designed to be optimized for specific frequency ranges (such as static, low-frequency dynamic, or high-frequency dynamic). This makes it difficult for a single system to simultaneously measure static pressure (close to 0 Hz) and dynamic pressure signals over a wide frequency range with high accuracy (especially when the signal frequency is unknown or varies).

[0004] In practical applications, especially in complex environments or when using miniature sensors (such as MEMS), the target pressure signal is often very weak and overwhelmed by strong noise (environmental noise, circuit noise, etc.). Traditional direct amplification or filtering methods are difficult to effectively extract such weak signals, resulting in insufficient measurement accuracy and signal-to-noise ratio (SNR).

[0005] To cover both static and dynamic pressure measurements across different frequency bands, existing solutions typically require deploying multiple sensor systems with varying frequency responses or complex multi-channel processing circuits. This not only increases system costs but also becomes a major obstacle to the miniaturization and integration of such systems.

[0006] To address the challenge of weak signal detection, lock-in amplification (LPA) technology, as a mature and highly sensitive detection method, is widely adopted. Its core principle is to use a reference signal with the same frequency and phase as the target signal for correlation detection, thereby significantly suppressing irrelevant noise. However, a key limitation of traditional LPA technology is that it requires a known and stable signal frequency to generate an accurate reference signal. For applications with unknown frequencies, drift, or requiring simultaneous detection of static (DC) and dynamic (AC) signals, traditional fixed-frequency or manually tuned LPAs fall short.

[0007] Therefore, developing a pressure detection system and method that can adapt to signal frequency, cover both static and dynamic pressure detection, and achieve high-precision weak signal extraction in strong noise background is of great significance for meeting the urgent needs of modern industry, scientific research and portable equipment for wide-frequency domain, high-precision and miniaturized pressure measurement. Summary of the Invention

[0008] To address the problem that existing weak pressure detection methods cannot cover both static and dynamic pressure at different frequency bands, this invention provides a weak pressure detection method and system. Data is collected by setting up a piezoelectric pressure sensor, a piezoelectric pressure sensor charge amplification and filtering circuit, and a piezoresistive pressure sensor full-bridge amplification and filtering circuit. The signal is then converted using an analog switching circuit and an ADC conversion circuit, and finally processed by a processor to complete the weak pressure detection.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] The first aspect of this invention proposes a weak pressure detection system, including a piezoelectric pressure sensor, a piezoresistive pressure sensor, a piezoelectric pressure sensor charge amplification and filtering circuit, a piezoresistive pressure sensor full-bridge amplification and filtering circuit, an analog switching circuit, an ADC conversion circuit, and a processor.

[0011] The piezoelectric pressure sensor charge amplification and filtering circuit includes a charge amplification circuit, a follower, and an amplification and filtering circuit. The input terminal of the charge amplification circuit is communicatively connected to the output terminal of the piezoelectric pressure sensor, the output terminal of the charge amplification circuit is electrically connected to the input terminal of the follower, and the output terminal of the follower is electrically connected to the input terminal of the amplification and filtering circuit, which facilitates the conversion of charge into a voltage signal.

[0012] The full-bridge amplification and filtering circuit of the piezoresistive pressure sensor includes a sensor full-bridge circuit and a differential amplification and filtering circuit. The input terminal of the sensor full-bridge circuit is electrically connected to the output terminal of the piezoresistive pressure sensor, and the output terminal is electrically connected to the input terminal of the differential amplification and filtering circuit, which facilitates the conversion of resistance changes caused by slight pressure changes into voltage signals.

[0013] The input terminal of the analog switch circuit is electrically connected to the output terminal of the differential amplifier filter circuit and the output terminal of the amplifier filter circuit, respectively. The output terminal of the analog switch circuit is electrically connected to the input terminal of the processor, which facilitates the sequential switching and transmission of signals from multiple piezoelectric or piezoresistive pressure sensors to the analog-to-digital converter.

[0014] Furthermore, the charge amplification circuit includes an SGM8521 amplifier, the follower includes an SGM8521 amplifier, the amplification and filtering circuit includes an SGM8521 amplifier, the output terminal of the piezoelectric pressure sensor is communicatively connected to the non-inverting terminal in the charge amplification circuit, the output terminal of the charge amplification circuit is electrically connected to the non-inverting terminal of the follower, and the output terminal of the follower is electrically connected to the inverting terminal of the amplification and filtering circuit.

[0015] Furthermore, the sensor full-bridge circuit includes a Wheatstone bridge structure and an adjustment circuit. The Wheatstone bridge structure includes a first varistor, a second varistor, a third varistor, and a fourth varistor. The adjustment circuit includes a second resistor and an adjustable resistor. One end of the adjustable resistor is connected to the input terminal of the fourth varistor, and the other end is connected to the output terminal of the third varistor. One end of the second resistor is electrically connected to the sliding end of the adjustable resistor, and the other end is electrically connected to the differential amplifier and filter circuit.

[0016] Furthermore, the differential amplifier and filter circuit includes an SGM8521 amplifier, a first resistor, a third resistor, and a fourth resistor. The output terminal of the sensor full-bridge circuit is connected to the non-inverting input of the SGM8521 amplifier through the first resistor and to the inverting input of the SGM8521 amplifier through the third resistor.

[0017] A fourth resistor is electrically connected between the non-inverting and inverting terminals of the SGM8521 amplifier in the differential amplifier filter circuit.

[0018] Furthermore, the analog switch circuit includes an ADG704 chip, the piezoelectric pressure sensor charge amplification and filtering circuit is electrically connected to the ADG704 chip via serial port S1, and the piezoelectric pressure sensor charge amplification and filtering circuit is electrically connected to the ADG704 chip via serial port S3.

[0019] Furthermore, the ADC conversion circuit includes an AD7472 chip, the Vin serial port of the AD7472 chip and the D serial port of the analog switch circuit are electrically connected to realize the conversion of analog signals to digital signals.

[0020] Furthermore, the processor includes a TMS320VC5509AGHH chip, a DSP device, and a parallel capacitor circuit. The output terminal of the ADC conversion circuit is electrically connected to the input terminal of the processor, and the output terminal of the processor is communicatively connected to the input terminal of the DSP device. One end of the parallel capacitor circuit is connected to the power supply terminal of the DSP device, and the other end is grounded. The DSP device includes a TMS320VC5509A.

[0021] A second aspect of the present invention provides a method for detecting weak pressure, comprising:

[0022] Step 1: Collect data information using piezoelectric and piezoresistive pressure sensors, and convert the data information into digital signals through a full-bridge amplification and filtering circuit for the piezoresistive pressure sensor, a charge amplification and filtering circuit for the piezoelectric pressure sensor, an analog switching circuit, and an ADC conversion circuit.

[0023] Step 2: The digital signal is transmitted to the processor, which converts the digital signal to obtain a frequency domain signal and analyzes the frequency domain signal to obtain the main frequency signal, which is convenient for subsequent processing of the main frequency signal;

[0024] Step 3: Generate a reference signal based on the main frequency signal, and process the main frequency signal using an orthogonal lock-in amplification algorithm based on the reference signal to obtain the amplitude of the main frequency signal;

[0025] Step 4: Superimpose and sum the amplitudes, then perform pressure magnitude inversion on the summed spectrum to obtain the pressure result.

[0026] Furthermore, the analysis of the frequency domain signal to obtain the main frequency signal includes:

[0027] Frequency domain signal analysis yields the first principal frequency signal, the second principal frequency signal, and the third principal frequency signal;

[0028] If the amplitude of the first primary frequency signal is greater than 10 times the amplitude of the second primary frequency signal and the amplitude of the first primary frequency signal is greater than a preset threshold, then the frequency domain signal has only the first primary frequency; if the amplitude of the first primary frequency signal is less than or equal to 10 times the amplitude of the second primary frequency signal and the amplitude of the second primary frequency signal is greater than 10 times the amplitude of the third primary frequency signal, then the signal consists of the first primary frequency and the second primary frequency signal.

[0029] The beneficial effects of this invention are:

[0030] This invention combines piezoelectric and piezoresistive sensors to enable a pressure detection system based on this weak pressure detection method to simultaneously detect static and dynamic pressure. This solves the problem that existing pressure detection systems can only detect static pressure, low-frequency dynamic pressure, or high-frequency dynamic pressure. It also overcomes the frequency limitations of single-type sensors. By using analog switches to multiplex ADC conversion circuits and processors, the hardware circuitry is simplified, the cost of multi-channel systems is reduced, and the miniaturization and integration of pressure detection systems are facilitated.

[0031] This invention achieves high-precision detection of weak pressure signals by employing an orthogonal phase-locked loop amplification algorithm based on FFT spectral analysis. Furthermore, the weak pressure detection method proposed in this invention is applicable to the detection of static pressure and dynamic pressure at different frequencies. Attached Figure Description

[0032] Figure 1 This is an architecture diagram of a weak pressure detection system provided in an embodiment of the present invention.

[0033] Figure 2The circuit diagrams for the piezoelectric pressure sensor charge amplification and filtering circuit, the piezoresistive pressure sensor full-bridge amplification and filtering circuit, the analog switching circuit, and the ADC conversion circuit provided in the embodiments of the present invention.

[0034] Figure 3 The circuit diagram of the charge amplification and filtering circuit of the piezoelectric pressure sensor provided in the embodiment of the present invention.

[0035] Figure 4 The circuit diagram of the full-bridge amplification and filtering circuit for the piezoresistive pressure sensor provided in the embodiment of the present invention.

[0036] Figure 5 A circuit diagram of a processor provided for an embodiment of the present invention.

[0037] Figure 6 This is a flowchart of a weak pressure detection method provided in an embodiment of the present invention.

[0038] Figure 7 The following is a flowchart illustrating a weak pressure detection method provided in an embodiment of the present invention.

[0039] The labels in the attached diagram are as follows: 1 is a piezoelectric pressure sensor, 2 is a piezoresistive pressure sensor, 3 is a charge amplification and filtering circuit for a piezoelectric pressure sensor, 4 is a full-bridge amplification and filtering circuit for a piezoresistive pressure sensor, 5 is an analog switch circuit, 6 is an ADC conversion circuit, 7 is a processor, 8 is a charge amplification circuit, 9 is a follower, 10 is an amplification and filtering circuit, 11 is a full-bridge circuit for the sensor, 12 is a differential amplification and filtering circuit, 13 is a Wheatstone bridge structure, 14 is an adjustment circuit, 15 is a parallel capacitor circuit, and 16 is a DSP device. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0041] Example 1

[0042] like Figure 1 and Figure 2As shown, a weak pressure detection system includes a piezoelectric pressure sensor, a piezoresistive pressure sensor, a piezoelectric pressure sensor charge amplification and filtering circuit 3, a piezoresistive pressure sensor full-bridge amplification and filtering circuit 4, an analog switching circuit 5, an ADC conversion circuit 6, and a processor 7. The piezoelectric pressure sensor includes an HPS 910-12030 sensor for high-frequency dynamic pressure measurement. The piezoresistive pressure sensor includes an ABP2269032 for static or low-frequency dynamic pressure measurement.

[0043] like Figure 3 As shown, the charge amplification and filtering circuit 3 of the piezoelectric pressure sensor includes a charge amplification circuit 8, a follower 9, and an amplification and filtering circuit 10. The input terminal of the charge amplification circuit 8 is communicatively connected to the output terminal of the piezoelectric pressure sensor, the output terminal of the charge amplification circuit 8 is electrically connected to the input terminal of the follower 9, and the output terminal of the follower 9 is electrically connected to the input terminal of the amplification and filtering circuit 10.

[0044] Specifically, the charge amplifier circuit 8 mainly converts the weak pressure signal from the piezoelectric pressure sensor into a voltage signal, the follower 9 mainly achieves impedance matching, and the amplification and filtering circuit 10 mainly amplifies and filters the signal to bring it up to the range of the analog-to-digital converter input voltage. The charge amplifier circuit 8, the follower 9, and the amplification and filtering circuit 10 all include an SGM8521 amplifier. The output terminal of the piezoelectric pressure sensor is communicatively connected to the non-inverting terminal of the charge amplifier circuit 8, the output terminal of the charge amplifier circuit 8 is electrically connected to the non-inverting terminal of the follower 9, and the output terminal of the follower 9 is electrically connected to the inverting terminal of the amplification and filtering circuit 10.

[0045] like Figure 4 As shown, the piezoresistive pressure sensor full-bridge amplification and filtering circuit 4 includes a sensor full-bridge circuit 11 and a differential amplification and filtering circuit 12. The output terminal of the sensor full-bridge circuit 11 and the input terminal of the differential amplification and filtering circuit 12 are electrically connected.

[0046] Specifically, the sensor full-bridge circuit 11 converts the resistance change caused by a slight change in pressure into a voltage signal. The sensor full-bridge circuit 11 includes a Wheatstone bridge structure 13 and an adjustment circuit 14. The Wheatstone bridge structure 13 includes a first varistor, a second varistor, a third varistor, and a fourth varistor. The adjustment circuit 14 includes a second resistor and an adjustable resistor. One end of the adjustable resistor is connected to the input terminal of the fourth varistor, and the other end is connected to the output terminal of the third varistor. One end of the second resistor is electrically connected to the sliding terminal of the adjustable resistor, and the other end is electrically connected to the differential amplifier and filter circuit 12.

[0047] Among them, the first piezoresistive resistor, the second piezoresistive resistor, the third piezoresistive resistor and the fourth piezoresistive resistor are all internal resistors of the piezoresistive pressure sensor.

[0048] The differential amplifier and filter circuit 12 primarily amplifies and filters the signal further than the signal amplification and filtering circuit 10, bringing it up to the range of the analog-to-digital converter input voltage. The differential amplifier and filter circuit 12 includes an SGM8521 amplifier, a first resistor, a third resistor, and a fourth resistor. The output terminal of the sensor full-bridge circuit is connected to the non-inverting input of the SGM8521 amplifier through the first resistor and to the inverting input through the third resistor. The fourth resistor, which serves as the gain resistor of the differential amplifier and filter circuit 12, is electrically connected between the non-inverting and inverting terminals of the SGM8521 amplifier.

[0049] The input terminal of the analog switch circuit 5 is electrically connected to the output terminal of the differential amplifier filter circuit 12 and the output terminal of the amplifier filter circuit 10, respectively. The output terminal of the analog switch circuit 5 is electrically connected to the input terminal of the processor 7.

[0050] Specifically, the analog switch circuit 5 includes an ADG704 chip. The piezoelectric pressure sensor charge amplification and filtering circuit 3 is electrically connected to the ADG704 chip via serial port S1, and the piezoelectric pressure sensor charge amplification and filtering circuit 3 is electrically connected to the ADG704 chip via serial port S3.

[0051] The ADC conversion circuit 6 includes an AD7472 chip, and the Vin serial port of the AD7472 chip is electrically connected to the D serial port of the analog switch circuit 5.

[0052] like Figure 5 As shown, the processor 7 includes a TMS320VC5509AGHH chip, a DSP device 16, and a parallel capacitor circuit 15. The output terminal of the ADC conversion circuit 6 is electrically connected to the input terminal of the processor 7, and the output terminal of the processor 7 is communicatively connected to the input terminal of the DSP device 16. One end of the parallel capacitor circuit 15 is connected to the power supply terminal of the DSP device 16, and the other end is grounded. Since the DSP device 16 requires multiple power supplies, the parallel capacitor circuit 15 eliminates power supply noise before supplying power to the DSP, ensuring the reliability of the DSP's operation, even in harsh environments. The DSP device 16 includes a TMS320VC5509A, which is the processor responsible for signal acquisition and data processing, stress inversion, and output.

[0053] Example 2

[0054] Based on the above embodiments, such as Figure 6 and Figure 7 As shown, this invention proposes a method for detecting weak pressure, specifically including:

[0055] S201: Data information is collected through piezoelectric pressure sensors and piezoresistive pressure sensors, and the data information is converted into digital signals through the piezoresistive pressure sensor full-bridge amplification and filtering circuit 4, the piezoelectric pressure sensor charge amplification and filtering circuit 3, the analog switch circuit 5, and the ADC conversion circuit 6.

[0056] S202: The digital signal is transmitted to the processor 7. The processor 7 converts the digital signal to obtain a frequency domain signal and analyzes the frequency domain signal to obtain the main frequency signal.

[0057] Specifically, processor 7 uses the FFT algorithm to convert the time-domain digital signal into a frequency-domain signal. The signal spectrum analysis module determines the main frequency components of the signal by analyzing the relationship between the amplitudes of the first, second, and third main frequency signals. If the amplitude of the first main frequency signal is greater than 10 times the amplitude of the second main frequency signal and is also greater than a preset threshold, then the signal contains only the first main frequency. If the amplitude of the first main frequency signal is not greater than 10 times the amplitude of the second main frequency signal, and the amplitude of the second main frequency signal is greater than 10 times the amplitude of the third main frequency signal, then the signal consists of both the first and second main frequency signals. This enables the identification of static pressure, dynamic low-frequency pressure, or dynamic high-frequency pressure.

[0058] S203: Generate a reference signal based on the main frequency signal, and process the main frequency signal using an orthogonal lock-in amplification algorithm based on the reference signal to obtain the amplitude of the main frequency signal.

[0059] Specifically, the calculation process of the quadrature lock-in amplification algorithm is as follows:

[0060] S203.1: Let the main frequency signal be... ,in The main frequency signal, It is noise.

[0061] S203.2: Combine the main frequency signal with the reference signal Frequency mixing is performed, where, The reference signal frequency is set by the initial scene (static: 0.1-10Hz, dynamic: 10Hz-1kHz).

[0062] S203.3: Extract the same-direction component X and the quadrature component Y through orthogonal demodulation.

[0063]

[0064]

[0065] Where T is the length of the integration time window, cos is the cosine function, sin is the sine function, and t is time t.

[0066] S203.4: Calculate the amplitude and phase based on the co-directional component X and the quadrature component Y, and output the modulation signal.

[0067] Specifically,

[0068]

[0069] Where A is the amplitude. is the phase, and arctan is the arctangent function.

[0070] S204: The amplitudes are summed and then the pressure magnitude is inverted from the summed spectrum to obtain the pressure result.

[0071] In summary, by replacing various sensor modules with different response frequencies, this invention enables the simultaneous detection of static and dynamic pressure in a pressure detection system based on this weak pressure detection method. This overcomes the limitation of existing pressure detection systems that can only detect static pressure, low-frequency dynamic pressure, or high-frequency dynamic pressure, thus facilitating the miniaturization of pressure detection systems. Furthermore, this invention employs a quadrature phase-locked amplification weak pressure signal extraction algorithm based on FFT spectral analysis, achieving high-precision detection of weak pressure signals. Moreover, the weak pressure detection method proposed in this invention is applicable to the detection of static pressure and dynamic pressure at different frequencies.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A weak pressure detection system, characterized in that, It includes a piezoelectric pressure sensor (1), a piezoresistive pressure sensor (2), a piezoelectric pressure sensor charge amplification and filtering circuit (3), a piezoresistive pressure sensor full-bridge amplification and filtering circuit (4), an analog switch circuit (5), an ADC conversion circuit (6), and a processor (7). The piezoelectric pressure sensor charge amplification and filtering circuit (3) includes a charge amplification circuit (8), a follower (9), and an amplification and filtering circuit (10). The input terminal of the charge amplification circuit (8) is communicatively connected to the output terminal of the piezoelectric pressure sensor (1). The output terminal of the charge amplification circuit (8) is electrically connected to the input terminal of the follower (9). The output terminal of the follower (9) is electrically connected to the input terminal of the amplification and filtering circuit (10). The full-bridge amplification and filtering circuit (4) of the piezoresistive pressure sensor includes a sensor full-bridge circuit (11) and a differential amplification and filtering circuit (12). The input terminal of the sensor full-bridge circuit (11) is electrically connected to the output terminal of the piezoresistive pressure sensor (2), and the output terminal is electrically connected to the input terminal of the differential amplification and filtering circuit (12). The input terminal of the analog switch circuit (5) is electrically connected to the output terminal of the differential amplifier filter circuit (12) and the output terminal of the amplifier filter circuit (10), respectively, and the output terminal of the analog switch circuit (5) is electrically connected to the input terminal of the processor (7).

2. The weak pressure detection system according to claim 1, characterized in that, The charge amplifier circuit (8) includes an SGM8521 amplifier, the follower (9) includes an SGM8521 amplifier, the amplification and filtering circuit (10) includes an SGM8521 amplifier, the output terminal of the piezoelectric pressure sensor (1) is communicatively connected to the in-phase terminal of the charge amplifier circuit (8), the output terminal of the charge amplifier circuit (8) is electrically connected to the in-phase terminal of the follower (9), and the output terminal of the follower (9) is electrically connected to the in-phase terminal of the amplification and filtering circuit (10).

3. The weak pressure detection system according to claim 1, characterized in that, The sensor full-bridge circuit (11) includes a Wheatstone bridge structure (13) and an adjustment circuit (14). The Wheatstone bridge structure (13) includes a first varistor, a second varistor, a third varistor, and a fourth varistor. The adjustment circuit (14) includes a second resistor and an adjustable resistor. One end of the adjustable resistor is connected to the input end of the fourth varistor, and the other end is connected to the output end of the third varistor. One end of the second resistor is electrically connected to the sliding end of the adjustable resistor, and the other end is electrically connected to the differential amplifier filter circuit (12).

4. The weak pressure detection system according to claim 3, characterized in that, The differential amplifier and filter circuit (12) includes an SGM8521 amplifier, a first resistor, a third resistor and a fourth resistor. The output terminal of the sensor full-bridge circuit (11) is connected to the non-inverting input of the SGM8521 amplifier through the first resistor and to the inverting input of the SGM8521 amplifier through the third resistor. A fourth resistor is electrically connected between the non-inverting and inverting terminals of the SGM8521 amplifier in the differential amplifier filter circuit (12).

5. A weak pressure detection system according to claim 1, characterized in that, The analog switch circuit (5) includes an ADG704 chip. The piezoelectric pressure sensor charge amplification and filtering circuit (3) is electrically connected to the ADG704 chip via the S1 serial port. The piezoelectric pressure sensor charge amplification and filtering circuit (3) is electrically connected to the ADG704 chip via the S3 serial port.

6. A weak pressure detection system according to claim 5, characterized in that, The ADC conversion circuit (6) includes an AD7472 chip, and the Vin serial port of the AD7472 chip is electrically connected to the D serial port of the analog switch circuit (5).

7. A weak pressure detection system according to claim 5, characterized in that, The processor (7) includes a TMS320VC5509AGHH chip, a DSP device (16), and a parallel capacitor circuit (15). The output terminal of the ADC conversion circuit (6) is electrically connected to the input terminal of the processor (7). The output terminal of the processor (7) is communicatively connected to the input terminal of the DSP device (16). One end of the parallel capacitor circuit (15) is connected to the power supply terminal of the DSP device (16), and the other end is grounded. The DSP device (16) includes a TMS320VC5509A.

8. A method for detecting weak pressure, characterized in that, include: Step 1: Collect data information through piezoelectric pressure sensor (1) and piezoresistive pressure sensor (2), and convert the data information into digital signals through piezoresistive pressure sensor full-bridge amplification and filtering circuit (4), piezoelectric pressure sensor charge amplification and filtering circuit (3), analog switch circuit (5) and ADC conversion circuit (6); Step 2: The digital signal is transmitted to the processor (7). The processor (7) converts the digital signal to obtain a frequency domain signal and analyzes the frequency domain signal to obtain the main frequency signal. Step 3: Generate a reference signal based on the main frequency signal, and process the main frequency signal using an orthogonal lock-in amplification algorithm based on the reference signal to obtain the amplitude of the main frequency signal; Step 4: Superimpose and sum the amplitudes, then perform pressure magnitude inversion on the summed spectrum to obtain the pressure result.

9. The method for detecting weak pressure according to claim 8, characterized in that, The analysis of the frequency domain signal to obtain the main frequency signals includes: Frequency domain signal analysis yields the first principal frequency signal, the second principal frequency signal, and the third principal frequency signal; If the amplitude of the first primary frequency signal is greater than 10 times the amplitude of the second primary frequency signal and the amplitude of the first primary frequency signal is greater than a preset threshold, then the frequency domain signal has only the first primary frequency; if the amplitude of the first primary frequency signal is less than or equal to 10 times the amplitude of the second primary frequency signal and the amplitude of the second primary frequency signal is greater than 10 times the amplitude of the third primary frequency signal, then the signal consists of the first primary frequency and the second primary frequency signal.

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