Gas sensing device and gas detection method

Abstract

The embodiment of the application discloses a kind of gas sensing device and gas detection method.Therein the device includes: substrate;With accommodating cavity photoacoustic cell is configured to accommodate target gas;Light source module is configured to emit modulation light of preset fixed frequency, to make target gas in accommodating cavity after absorption modulation light produce photoacoustic signal;Inertial measurement unit is set on substrate;Inertial measurement unit is configured to collect vibration interference signal of environmental vibration;Collecting module is placed on substrate;Collecting module is configured to collect mixed signal containing photoacoustic signal and vibration interference signal;Detection component is configured to cancel vibration interference in mixed signal based on adaptive algorithm, and extract photoacoustic signal in mixed signal matched with preset fixed frequency by lock-in demodulation, obtain the concentration value of target gas after conversion output pure photoacoustic signal.By the embodiment of the application, to solve how to effectively suppress the technical problem of wideband vibration interference.

Description

Technical Field

[0001] This application relates to the field of gas sensor technology, and in particular to a gas sensing device and a gas detection method. Background Technology

[0002] Photoacoustic spectroscopy (PAS) gas detection technology relies on the photoacoustic effect to detect gases: gas molecules absorb modulated light of a specific wavelength and undergo periodic thermal expansion and contraction, generating a photoacoustic signal. This acoustic signal is collected by a microphone, and the corresponding gas concentration is calculated through data processing. It has outstanding advantages such as excellent gas selectivity and fast response speed. Among them, non-resonant photoacoustic spectroscopy sensors have been widely used in various scenarios such as automotive and industrial equipment due to their simple structure, low cost, and wide linear detection range.

[0003] However, when these sensors are used in actual operating environments such as engines and air conditioning compressors, there are still several difficult technical challenges to overcome: 1. The modulation frequency of the infrared light source of the non-resonant PAS sensor is fixed in the range of 10~50Hz, while the main frequency of engine vibration is concentrated in the range of 10~100Hz and the main frequency of air conditioning compressor vibration is 15~80Hz. The frequency ranges of the two overlap significantly, causing signal aliasing interference in the same frequency band. 2. Vibration interference can couple to the microphone in three ways, introducing false signals: First, vibration directly causes the microphone diaphragm to move inertia, generating false electrical signals; second, vibration causes slight displacement of optical components such as the photoacoustic cell, light source, and lens, causing fluctuations in optical power and generating false photoacoustic signals; third, vibration induces mechanical resonance in the photoacoustic cell, further amplifying acoustic interference noise. 3. When the effective signal and interference noise are in the same frequency band, conventional high-pass and band-pass frequency domain filtering methods are difficult to distinguish between the two, which directly causes the signal-to-noise ratio of the photoacoustic signal to decrease, the gas concentration detection accuracy to drop, and phenomena such as measurement value jumps and zero-point drift to occur, which greatly weakens the reliability of the sensor under strong vibration conditions.

[0004] Currently, mainstream anti-interference solutions all have obvious shortcomings: mechanical vibration reduction structures such as silicone buffer pads and suspension brackets have limited vibration reduction performance and will also sacrifice sensor detection sensitivity; dual-microphone differential noise reduction solutions not only have high hardware costs and are difficult to design acoustic structures, but are also difficult to adapt to wide-frequency vibration conditions. Summary of the Invention

[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a gas sensing device and a gas detection method to solve the technical problem of how to effectively suppress broadband vibration interference.

[0006] In a first aspect, this application provides a gas sensing device, comprising: substrate; A photoacoustic cell with a receiving cavity is disposed on the substrate; the receiving cavity is configured to contain a target gas. A light source module is placed in the receiving cavity; the light source module is configured to emit modulated light of a preset fixed frequency so that the target gas in the receiving cavity absorbs the modulated light and generates a photoacoustic signal; An inertial measurement unit is disposed on the substrate; the inertial measurement unit is configured to acquire vibration interference signals of environmental vibrations; A data acquisition module is placed on the substrate; the data acquisition module is configured to acquire a mixed signal containing the photoacoustic signal and the vibration interference signal; The detection component is configured to cancel vibration interference in the mixed signal based on an adaptive algorithm, and extract the photoacoustic signal in the mixed signal that matches the preset fixed frequency through phase-locked demodulation, and then calculate and output the concentration value of the target gas after obtaining a pure photoacoustic signal.

[0007] In at least some embodiments of this application, The detection component includes a preprocessing module configured to preprocess the mixed signal and the vibration interference signal; the preprocessing includes any one of the following: The mixed signal is amplified and filtered to obtain a mixed signal with high-frequency noise suppressed. The vibration interference signal is subjected to low-pass filtering and normalization. The mixed signal and vibration interference signal are sampled synchronously at a certain sampling frequency and converted into digital signals.

[0008] In at least some embodiments of this application, The detection component includes an interference cancellation module; the interference cancellation module is configured to estimate the vibration interference using an adaptive algorithm with reference to the vibration interference signal, cancel the vibration interference from the mixed signal, and output an initial pure photoacoustic signal.

[0009] In at least some embodiments of this application, The detection component includes a phase-locked demodulation module, which is configured to synchronously detect the initial pure photoacoustic signal, generate a carrier wave with the same frequency and phase as the preset fixed frequency to extract the photoacoustic signal, and output the final pure photoacoustic signal.

[0010] In at least some embodiments of this application, The detection component includes a conversion module, which is configured to convert the pure photoacoustic signal based on ambient temperature data and a calibration model to obtain the concentration value of the target gas.

[0011] In at least some embodiments of this application, The modulated light is infrared light, and the center wavelength of the infrared light is the characteristic absorption peak of the target gas.

[0012] In a second aspect, this application provides a gas detection method based on a gas sensing device as described in any one of the first aspects; the method includes: Obtain a mixed signal containing the photoacoustic signal and the vibration interference signal; The vibration interference in the mixed signal is canceled by an adaptive algorithm, and the photoacoustic signal matching the preset fixed frequency in the mixed signal is extracted by phase-locked demodulation. After obtaining the pure photoacoustic signal, the concentration value of the target gas is calculated and output.

[0013] In at least some embodiments of this application, The method further includes: preprocessing the mixed signal and the vibration interference signal; the preprocessing includes any one of the following: The mixed signal is amplified and filtered to obtain a mixed signal with high-frequency noise suppressed. The vibration interference signal is subjected to low-pass filtering and normalization. The mixed signal and vibration interference signal are sampled synchronously at a certain sampling frequency and converted into digital signals.

[0014] In at least some embodiments of this application, The sampling frequency is greater than 100Hz, and the ratio of the sampling frequency to the preset fixed frequency is greater than or equal to 5:1.

[0015] In at least some embodiments of this application, The adaptive algorithm-based cancellation of vibration interference in the mixed signal includes: Using the vibration interference signal as a reference, the vibration interference is estimated through an adaptive algorithm, and the vibration interference is canceled out from the mixed signal to output an initial pure photoacoustic signal.

[0016] In at least some embodiments of this application, The step of extracting the photoacoustic signal matching the preset fixed frequency from the mixed signal through phase-locked demodulation to obtain a pure photoacoustic signal includes: The initial pure photoacoustic signal is synchronously detected to generate a carrier wave with the same frequency and phase as the preset fixed frequency to extract the photoacoustic signal and output the final pure photoacoustic signal.

[0017] In at least some embodiments of this application, The process of converting the obtained pure photoacoustic signal into the output concentration value of the target gas includes: The concentration value of the target gas is obtained by converting the pure photoacoustic signal based on the ambient temperature data and calibration model.

[0018] In a third aspect, this application provides an electronic device including a memory, one or more processors, and one or more application programs, wherein the one or more application programs are stored in the memory and are configured to, when invoked by the one or more processors, cause the one or more processors to perform the method as described in any one of the second aspects.

[0019] In a fourth aspect, this application provides a computer-readable storage medium storing a plurality of program codes adapted to be loaded and run by a processor to perform the method as described in any one of the second aspects.

[0020] The above-described technical solutions of this application have at least one or more of the following beneficial effects: In implementing the technical solution of this application, an inertial measurement unit is added to collect vibration interference signals. An adaptive algorithm within the detection component is used to cancel out vibration interference of the same frequency band in the mixed signal. Then, phase-locked demodulation is used to extract the effective photoacoustic signal and calculate the gas concentration. This effectively solves the shortcomings of traditional non-resonant PAS sensors in strong vibration environments such as engines and compressors, where the light source modulation frequency overlaps with the equipment vibration frequency band, conventional filtering cannot separate interference, mechanical vibration damping reduces sensitivity, and dual-microphone differential sensors are costly and only suitable for narrowband vibration. This application relies on LMS adaptive filtering to dynamically fit various broadband vibration interferences, eliminating the need for complex acoustic structures and vibration damping components. It has low hardware cost and a simple structure. While suppressing pseudo-electrical signals, pseudo-photoacoustic signals, and resonance noise caused by vibration, it fully preserves detection sensitivity and eliminates zero-point drift and reading jumps. Combined with phase-locked demodulation to filter out residual clutter and temperature compensation to correct concentration, it doubly improves the signal-to-noise ratio and measurement accuracy. Furthermore, the various modules of the device are integrated on the substrate, resulting in high integration and compact size. Synchronous sampling ensures signal timing alignment, the algorithm has low computational load and stable convergence, and can output accurate concentration in real time. It is suitable for various wide-frequency and strong vibration conditions such as vehicle and industrial equipment, and has excellent versatility and mass production capability.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the drawings are used to denote similar components, wherein: Figure 1This is a schematic diagram of the structure of a gas sensing device according to an embodiment of this application; Figure 2 This is a schematic diagram of the working process of a gas sensing device according to an embodiment of this application; Figure 3 This is a schematic flowchart of the main steps of a gas detection method according to an embodiment of this application; Figure 4 This is a schematic flowchart of a gas detection method according to an embodiment of this application; Figure 5 This is a schematic diagram illustrating the interference separation principle of a gas detection method according to an embodiment of this application. Detailed Implementation

[0023] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0024] To address the issue of co-frequency interference in non-resonant PAS sensors under strong vibration environments, this application provides a vibration interference suppression device and method based on an inertial measurement unit. It achieves accurate estimation and cancellation of vibration interference through an adaptive algorithm, and combines phase-locked demodulation to extract pure photoacoustic signals, thereby improving the accuracy and stability of gas detection. Specifically, refer to... Figure 1 , Figure 1 This is a structural diagram of a gas sensing device according to an embodiment of this application. An embodiment of the gas sensing device of this application includes: substrate 100; A photoacoustic cell 200 with a receiving cavity is disposed on a substrate 100; the receiving cavity is configured to contain a target gas. A light source module 300 is placed in a receiving cavity; the light source module 300 is configured to emit modulated light of a preset fixed frequency so that the target gas in the receiving cavity absorbs the modulated light and generates a photoacoustic signal. An inertial measurement unit 400 is disposed on a substrate 100; the inertial measurement unit 400 is configured to acquire vibration interference signals of environmental vibrations; Acquisition module 500 is placed on the substrate; acquisition module 500 is configured to acquire a mixed signal including photoacoustic signal 1 and vibration interference signal; The detection component is configured to cancel vibration interference in the mixed signal based on an adaptive algorithm, and extract the photoacoustic signal that matches the preset fixed frequency in the mixed signal through phase-locked demodulation. After obtaining the pure photoacoustic signal, the concentration value of the target gas is calculated and output.

[0025] It is understood that the gas sensing device in this application embodiment detects and collects the triaxial acceleration signal, i.e., vibration interference signal, generated by environmental vibration in real time through the input inertial measurement unit, analyzes and calculates the influence of strong environmental vibration on the PAS photoacoustic signal, and compensates for it to suppress the influence of environmental vibration interference on the measurement accuracy of the gas sensor; the phase-locked demodulation further extracts the photoacoustic component that is synchronized with the fixed frequency of the modulation light, suppresses residual asynchronous noise, and finally obtains a pure photoacoustic signal.

[0026] The substrate 100 can be a support plate for carrying the devices or a circuit board, through which the devices are electrically connected. If the substrate 100 is a circuit board, the detection component can also be mounted on the circuit board and electrically connected to the light source module 300, the inertial measurement unit 400, and the acquisition module 500.

[0027] The photoacoustic cell 200 is a non-resonant photoacoustic cell, providing a space for the absorption of the target gas; it is equipped with a breathable membrane window 201 to allow air to enter the containment cavity; Reference Figure 1 The photoacoustic cell 200 contains target gas molecules 101 and air molecules 102. The target gas molecules 101 absorb modulated light and undergo non-radiative relaxation to generate a periodic temperature rise, thereby inducing thermal expansion and contraction of the gas to form a photoacoustic signal 103. Furthermore, the photoacoustic cell 200 is made of stainless steel or copper, etc.

[0028] Among them, the light source module 300 is an infrared light source that emits infrared light modulated at a preset fixed frequency (10-50Hz). The center wavelength of the infrared light is the characteristic absorption peak of CO2 or the characteristic absorption peak of other gases. For example, infrared light with the characteristic absorption peak of CO2 at 4.26μm is pulsed at a fixed frequency of 20Hz (square wave modulation, amplitude 5V).

[0029] The inertial measurement unit 400 can be an IMU or a multi-axis accelerometer, which acquires triaxial acceleration signals of environmental vibrations in real time. x a y a z This refers to vibration interference signals; for example, ICM-20602, etc., can be detected through I... 2 The C interface communicates with the detection component, i.e., the main control element.

[0030] Among them, the acquisition module 500 is a microphone, such as SPH0641LM4H, with a sensitivity of -26dBV / Pa.

[0031] The detection component can be integrated onto the substrate 100 or it can be a separate signal processing or control unit. The detection component can be understood as a complete control unit or a control component composed of multiple modules. It can be configured according to actual needs, and this application does not limit it, as long as the above functional design requirements are met.

[0032] In this embodiment, an inertial measurement unit 400 is added to collect vibration interference signals. An adaptive algorithm within the detection component is used to cancel out vibration interference in the same frequency band from the mixed signal. Then, phase-locked demodulation is used to extract the effective photoacoustic signal and calculate the gas concentration. This effectively solves the shortcomings of traditional non-resonant PAS sensors in strong vibration environments such as engines and compressors, where the light source modulation frequency overlaps with the equipment vibration frequency band, conventional filtering cannot separate interference, mechanical vibration damping reduces sensitivity, and dual-microphone differential sensors are costly and only suitable for narrowband vibration. This application relies on LMS adaptive filtering to dynamically fit various broadband vibration interferences, eliminating the need for complex acoustic structures and vibration damping components. It boasts low hardware cost and a simple structure. While suppressing pseudo-electrical signals, pseudo-photoacoustic signals, and resonance noise caused by vibration, it fully preserves detection sensitivity and eliminates zero-point drift and reading jumps. Combined with phase-locked demodulation to filter out residual clutter and temperature compensation to correct concentration, it doubly improves the signal-to-noise ratio and measurement accuracy. Furthermore, the various modules of the device are integrated on the substrate, resulting in high integration and compact size. Synchronous sampling ensures signal timing alignment, the algorithm has low computational load and stable convergence, and can output accurate concentration in real time. It is suitable for various wide-frequency and strong vibration conditions such as vehicle and industrial equipment, and has excellent versatility and mass production capability.

[0033] In one embodiment, the detection component includes a preprocessing module configured to preprocess the mixed signal and the vibration interference signal; the preprocessing includes any of the following: The mixed signal is amplified and filtered to obtain a mixed signal with high-frequency noise suppressed; specifically, the mixed signal is amplified by a certain gain and high-frequency noise is suppressed by a low-pass filter with a cutoff frequency (e.g., 50Hz). Low-pass filtering (e.g., cutoff 500Hz) and normalization are applied to vibration interference signals to improve signal correlation. The mixed signal and vibration interference signal are sampled synchronously at a certain sampling frequency and converted into digital signals to ensure time alignment; if the sensor has a digital output, clock synchronization is performed directly.

[0034] Each of these components can be a single module within the detection assembly. For example: a preamplifier and anti-aliasing filter module performs gain amplification and filtering on the mixed signal to obtain a mixed signal after suppressing high-frequency noise; a vibration signal preprocessing module performs low-pass filtering and normalization on the vibration interference signal; and a digital synchronous sampling module synchronously samples the mixed signal and vibration interference signal at a certain sampling frequency and converts them into digital signals to ensure time alignment. In one specific implementation, the preamplifier and anti-aliasing filter module can use an instrumentation amplifier such as AD8421, combined with an RC low-pass filter; the digital synchronous sampling module can use a 12-bit ADC such as STM32F103, with channel 1 acquiring the mixed signal and channel 2 acquiring the vibration interference signal.

[0035] In one embodiment, the detection component includes an interference cancellation module; the interference cancellation module is configured to estimate the vibration interference using an adaptive algorithm with reference to the vibration interference signal, cancel the vibration interference from the mixed signal, and output an initial clean photoacoustic signal. The LMS adaptive algorithm constructs a mapping relationship between the inertial measurement signal and the vibration interference through iterative learning, accurately estimates the interference, and cancels it from the mixed signal.

[0036] In one specific implementation, the detection component includes a phase-locked demodulation module, which is configured to synchronously detect the initial pure photoacoustic signal, generate a carrier wave with the same frequency and phase as a preset fixed frequency to extract the photoacoustic signal, that is, track the modulation frequency of the infrared light source - the preset fixed frequency f0, extract the amplitude of the photoacoustic signal with the same frequency and phase as f0, and output the final pure photoacoustic signal.

[0037] In one specific implementation, the detection component includes a conversion module configured to convert the pure photoacoustic signal based on ambient temperature data and a calibration model to obtain the concentration value of the target gas. Specifically, the device also includes a temperature sensor for measuring the ambient temperature. Based on the measured ambient temperature, the concentration (ppm) of the target gas is calculated using the calibration model, and the final concentration value is output. This calibration model is obtained by fitting experimental data under different temperatures, different CO2 concentrations, and different vibration intensities. The temperature sensor is an NTC temperature sensor, such as the MF52A103F3950, with a measurement range of -40~125℃ and an accuracy of ±0.5℃.

[0038] Among them, the interference cancellation module, phase-locked demodulation module, and conversion module can use a unified integrated chip, such as STM32F103C8T6, which is responsible for algorithm operation, data processing, and communication.

[0039] Based on the above implementation methods, refer to Figure 2 A structural block diagram of a gas sensing device according to an embodiment of this application, and a possible working process: The infrared light source module generates infrared light at the center wavelength, using pulse modulation at a fixed frequency fo. The non-resonant photoacoustic cell receives CO2 gas and vibration interference signals generated by the vibration of an engine or air conditioning compressor; after CO2 molecules absorb infrared light, they form photoacoustic signals that mix with the vibration interference signals and enter the MEMS microphone. The MEMS microphone detected a mixed signal containing photoacoustic signals and vibration interference; An inertial measurement unit (IMU or triaxial accelerometer) acquires triaxial acceleration signals of environmental vibrations in real time; a vibration signal preprocessing module performs low-pass filtering (e.g., cutoff to 500Hz) and normalization on the inertial measurement signals; The preamplifier and anti-aliasing filter module amplifies the microphone mixed signal by a certain gain and suppresses high-frequency noise by using a low-pass filter with a cutoff frequency (such as 50Hz). The digital synchronous sampling module synchronously acquires the microphone preprocessed signal and the inertial measurement preprocessed signal at a certain sampling rate to ensure time alignment; The interference cancellation module uses the vibration interference signal from inertial measurement as a reference, estimates the vibration interference through an adaptive algorithm, cancels the interference from the microphone mixed signal, and outputs an initial pure photoacoustic signal. The phase-locked demodulation module tracks the modulation frequency f0 of the infrared light source, extracts the amplitude of the photoacoustic signal that is in phase and frequency with f0, and outputs the final pure photoacoustic signal. The conversion module combines ambient temperature data measured by the NTC temperature sensor and converts CO2 concentration using a calibration model. Concentration output module via UART / I 2 The final concentration value is output via the C interface.

[0040] Further, refer to Figure 3 This is a schematic flowchart illustrating the main steps of a gas detection method according to an embodiment of this application. The method is based on the gas sensing device described above and mainly includes steps S101-S102: Step S101: Acquire a mixed signal containing photoacoustic signals and vibration interference signals; Step S102: Based on the adaptive algorithm, the vibration interference in the mixed signal is canceled out, and the photoacoustic signal matching the preset fixed frequency in the mixed signal is extracted by phase-locked demodulation. After obtaining the pure photoacoustic signal, the concentration value of the target gas is calculated and output.

[0041] In one embodiment, reference Figure 4 Gas detection methods specifically include: Step S1: Signal generation: The light source module modulates at a fixed frequency of 10-50Hz and emits infrared light into the non-resonant photoacoustic cell; the gas absorbs the light energy to generate a photoacoustic signal s(t), while the environmental vibration generates an interference signal n_vib(t) through structural coupling; Step S2: Signal Acquisition: The microphone acquires the mixed signal x(t) = s(t) + n_vib(t) + η(t) (η(t) is thermal noise); the inertial measurement unit synchronously acquires the environmental reference signal, i.e., the vibration interference signal a(t) = [a x (t),a y (t),a y (t) (inertial measurement signal); Step S3: Signal preprocessing: The microphone mixed signal is pre-amplified and anti-aliasing filtered, and then sampled by the ADC and converted into a digital signal; the inertial measurement signal is low-pass filtered and normalized, and then sampled synchronously with the mixed signal collected by the microphone to ensure time alignment. Step S4: LMS Adaptive Interference Cancellation Algorithm: Construct an LMS adaptive filter, using the inertial measurement signal as the reference input and the digital signal converted from the mixed signal collected by the microphone as the main input. Estimate and cancel vibration interference using the following method: 1) Interference estimation: N_vib(n) = W (n) U(n), where W(n) is the adaptive weight vector and U(n) is the inertial measurement reference vector (including the current and historical values ​​of the IMU or acceleration). 2) Error signal: e(n) = X(n) - N_vib(n) (e(n) is the photoacoustic signal after cancellation); 3) Weight update: W(n+1) = W(n) + μ e(n) U(n), where μ is the step size factor, which ensures the convergence of the algorithm; Step S5: Phase-locked demodulation: Synchronous detection is performed on the error signal e(n) to generate a sine / cosine carrier wave with the same frequency and phase as the modulation frequency f0. After multiplication mixing and low-pass filtering, the amplitude of the photoacoustic signal A=SQRT(I²+Q²) (I is the in-phase component and Q is the quadrature component) is extracted. Depending on the applicable scenario and working conditions, Hilbert transform may be used to improve efficiency. S6: Concentration Conversion: Combining the ambient temperature T measured by the NTC temperature sensor, the concentration is calculated using the calibration model C=k0. A+k1 T+k2 A The CO2 concentration is converted using T+C0 (k0, k1, and k2 are calibration coefficients, and C0 is the zero-point offset), and the final output concentration value is obtained.

[0042] In one specific implementation, the gas detection method includes: Initial configuration: Configure the infrared light source modulation frequency to 20Hz and the vibration measurement sampling rate to 100Hz; Data Acquisition: The MCU synchronously acquires microphone signals and IMU or triaxial acceleration signals via ADC or digital interface, and then transmits the data through I... 2 C reads NTC temperature data; LMS adaptive cancellation: a) Constructing the IMU reference vector U(n) = [a x (n),a y (n),a z (n),a x (n-1),a y (n-1),a z (n-1)]; b). Calculate the interference estimate N_vib(n) = W (n)•U(n); c). Calculate the error signal e(n) = X(n) - N_vib(n); d) Update the weights W(n+1) = W(n) + μ•e(n)•U(n); Phase-locked demodulation: a) Generate 20Hz synchronous carriers sin(2πf0t) and cos(2πf0t); b). Frequency mixing: I(n) = e(n)•cos(2πf0t), Q(n) = e(n)•sin(2πf0t); c) Low-pass filtering: A first-order IIR filter is used to smooth the I and Q components; c). Amplitude calculation: A(n) = SQRT(I) filt (n)²+Q filt (n)²); Alternatively, depending on the applicable scenario and operating conditions, the Hilbert transform can also be used to improve efficiency.

[0043] Concentration conversion: Using calibration coefficients k0, k1, k2, and C0, calculate the concentration C = k0. A+k1 T+k2 A T+C0; Output: Output CO2 concentration value via UART interface (e.g., baud rate 9600bps).

[0044] Among them, the reference vector U(n) of the LMS adaptive interference cancellation module contains the current and historical values ​​of the IMU or multi-axis acceleration, and the vector order is 3 to 8. The ADC sampling rate is greater than 100Hz, and the ratio of the ADC sampling rate to the infrared light source modulation frequency is ≥5:1 to ensure signal sampling integrity.

[0045] Based on the above steps S101-S106, refer to Figure 5 The core principle of the method in this embodiment is interference separation based on signal correlation. Even if the photoacoustic signal and vibration interference are in the same frequency band, they can still be accurately separated through the following characteristics: the photoacoustic signal s(t) is strictly synchronized with the modulation frequency f0 of the infrared light source and is statistically independent of the vibration reference signal a(t) (correlation ≈ 0); the vibration interference n_vib(t) is caused by environmental vibration and is highly correlated with the inertial measurement reference signal a(t); the LMS adaptive algorithm constructs a mapping relationship between the inertial measurement signal and the vibration interference through iterative learning, accurately estimates the interference and cancels it out from the mixed signal; the phase-locked demodulation further extracts the photoacoustic component synchronized with f0, suppresses residual asynchronous noise, and finally obtains a pure photoacoustic signal.

[0046] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effect of this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of this application.

[0047] Based on the above-mentioned gas sensing device and gas detection method, the following effects are achieved: To address the challenge of interference from vibrations in the same frequency band and significantly improve the detection accuracy under strong vibration conditions, this application's device adds an inertial measurement unit to synchronously acquire environmental vibration reference signals. It then uses an adaptive algorithm to model and cancel broadband vibration interference within the mixed signal. Addressing the pain points of existing non-resonant PAS sensors (10-50Hz light source modulation frequency) overlapping with the 10-100Hz vibration frequency band of engines and air conditioning compressors, where traditional filtering methods cannot separate interference and mechanical vibration reduction / dual-microphone differential solutions have significant shortcomings, this device eliminates pseudo-electrical signals, pseudo-photoacoustic signals, and photoacoustic cell resonance amplification noise introduced by vibrations in the same frequency band without relying on complex vibration reduction structures and high-cost dual microphones. This effectively improves the signal-to-noise ratio, eliminates reading jumps and zero-point drift, and significantly enhances the stability of gas concentration measurement in high-vibration scenarios such as vehicle-mounted and industrial applications.

[0048] Adaptive interference suppression adapts to full-bandwidth vibration scenarios, making it more versatile: It adopts the LMS adaptive filtering algorithm, using the triaxial acceleration signal output by the inertial measurement unit as the interference reference. It can iteratively update the filtering weights in real time and dynamically fit the mapping relationship of environmental vibration interference of different intensities and frequencies, without being limited by the vibration frequency band. Compared with the shortcomings of traditional dual-microphone differential structures that are only suitable for narrowband vibration and have complex acoustic design, this solution can be compatible with a variety of wideband vibration devices such as engines and compressors, and the device is applicable to a wider range of scenarios.

[0049] The hardware structure is simple, the cost is controllable, and it is easy to mass produce: the hardware only adds a conventional IMU / triaxial accelerometer inertial measurement unit, without the need for additional high-precision acoustic devices, multi-layer suspension vibration damping brackets or dual-channel microphone acoustic structures. The overall structure is simple and the hardware material cost is low. At the same time, it avoids the problems of photoacoustic signal attenuation and sensor sensitivity reduction caused by silicone pads and suspension vibration damping structures. While suppressing vibration interference, it fully preserves the original photoacoustic signal amplitude, taking into account both anti-interference ability and detection sensitivity.

[0050] Signal link collaborative processing further purifies the effective photoacoustic signal: After obtaining a pure photoacoustic error signal by offsetting vibration interference through an adaptive algorithm, the matching phase-locked demodulation module accurately tracks the preset modulation frequency of the light source, extracts only the effective photoacoustic component synchronized with the modulation frequency, and filters out residual random thermal noise and asynchronous clutter; then, combined with an NTC temperature sensor, temperature compensation calibration is completed, and the output concentration is corrected through a dedicated concentration model. The combination of dual noise reduction and temperature correction further reduces measurement error and improves the detection accuracy of target gases such as CO2.

[0051] The modular architecture boasts high integration and is adaptable to miniaturized vehicle / industrial equipment: the infrared light source and acoustic signal acquisition module are integrated inside the photoacoustic cell, while the inertial measurement unit and signal processing and detection components are uniformly mounted on the substrate, resulting in high overall integration and compact size; the synchronous ADC sampling unit achieves clock alignment between the vibration reference signal and the acoustic mixed signal, ensuring the timing accuracy of the adaptive algorithm's interference estimation. The entire device can be adapted to compact installation spaces such as narrow vehicle cavities and industrial airborne equipment, and has excellent miniaturization and embedded adaptability.

[0052] The algorithm converges stably, and its real-time performance meets the requirements of industrial online detection: The LMS adaptive filter uses a reference vector that includes historical acceleration time-series values ​​for iterative calculation, and the controllable step size parameter ensures rapid algorithm convergence; the synchronous sampling rate is more than 5 times higher than the light source modulation frequency, which can achieve complete signal acquisition without aliasing distortion. The entire signal processing flow has a moderate amount of computation, and the MCU can perform the entire process without the need for a high-performance computing chip. It can output stable and accurate gas concentration data in real time, meeting the requirements of continuous online monitoring of equipment.

[0053] Furthermore, this application also provides an electronic device, including a memory, one or more processors, and one or more application programs, wherein the one or more application programs are stored in the memory, and the one or more application programs are configured to cause the one or more processors to perform the method described in any of the preceding technical solutions when invoked by the one or more processors.

[0054] The electronic device in this application mainly includes a memory and a processor. The memory can be configured to store a program for executing the methods of the above method embodiments, and the processor can be configured to execute the program in the memory. The program includes, but is not limited to, a program for executing the methods of the above method embodiments. For ease of explanation, only the parts related to the embodiments of this application are shown. For specific technical details not disclosed, please refer to the method section of the embodiments of this application.

[0055] In the embodiments of this application, the electronic device may be a control device comprising various electronic components. In some possible implementations, the electronic device may include multiple storage devices and multiple processors. The program executing the method of the above method embodiments may be divided into multiple subroutines, each subroutine may be loaded and run by a processor to execute different steps of the method of the above method embodiments. Specifically, each subroutine may be stored in different memories, and each processor may be configured to execute programs in one or more memories to jointly implement the method of the above method embodiments, that is, each processor executes different steps of the method of the above method embodiments to jointly implement the method of the above method embodiments.

[0056] The aforementioned electronic equipment is used to perform Figure 3 The method embodiments shown are similar in technical principle, technical problem solved and technical effect produced. Those skilled in the art can clearly understand that, for the sake of convenience and brevity, the specific working process of the electronic device and related descriptions can be referred to the content described in the method embodiments, and will not be repeated here.

[0057] The aforementioned multiple processors can be processors deployed on the same device. For example, the aforementioned computer device can be a high-performance device composed of multiple processors, and the aforementioned multiple processors can be processors configured on that high-performance device. Alternatively, the aforementioned multiple processors can also be processors deployed on different devices. For example, the aforementioned computer device can be a server cluster, and the aforementioned multiple processors can be processors on different servers within the server cluster.

[0058] Those skilled in the art will understand that all or part of the processes in the method of the above-described embodiment can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0059] Furthermore, this application also provides a computer-readable storage medium. In one embodiment of the computer-readable storage medium according to this application, the computer-readable storage medium can be configured to store a program that performs the methods of the above-described method embodiments, the program of which can be loaded and run by a processor to implement the above-described methods. For ease of explanation, only the parts related to the embodiments of this application are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of this application. The computer-readable storage medium can be a storage device device comprising various electronic devices. Optionally, in the embodiments of this application, the computer-readable storage medium is a non-transitory computer-readable storage medium.

[0060] Furthermore, it should be understood that since the various modules are only provided to illustrate the functional modules of the device described in this application, the physical devices corresponding to these modules may be the processor itself, or a part of the processor's software, hardware, or a combination of both. Therefore, the number of modules shown in the figures is merely illustrative. Those skilled in the art will understand that the various modules in the system can be adaptively split or merged. Such splitting or merging of specific modules will not cause the technical solution to deviate from the principles of this application; therefore, the technical solutions after splitting or merging will fall within the protection scope of this application.

[0061] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0062] 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 this application. 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.

[0063] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0064] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0065] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A gas sensing device, characterized in that, include: substrate; A photoacoustic cell with a receiving cavity is disposed on the substrate; the receiving cavity is configured to contain a target gas. A light source module is placed in the receiving cavity; the light source module is configured to emit modulated light of a preset fixed frequency so that the target gas in the receiving cavity absorbs the modulated light and generates a photoacoustic signal; An inertial measurement unit is disposed on the substrate; the inertial measurement unit is configured to acquire vibration interference signals of environmental vibrations; A data acquisition module is placed on the substrate; the data acquisition module is configured to acquire a mixed signal containing the photoacoustic signal and the vibration interference signal; The detection component is configured to cancel vibration interference in the mixed signal based on an adaptive algorithm, and extract the photoacoustic signal in the mixed signal that matches the preset fixed frequency through phase-locked demodulation, and then calculate and output the concentration value of the target gas after obtaining a pure photoacoustic signal.

2. The gas sensing device according to claim 1, characterized in that, The detection component includes a preprocessing module configured to preprocess the mixed signal and the vibration interference signal; the preprocessing includes any one of the following: The mixed signal is amplified and filtered to obtain a mixed signal with high-frequency noise suppressed. The vibration interference signal is subjected to low-pass filtering and normalization. The mixed signal and vibration interference signal are sampled synchronously at a certain sampling frequency and converted into digital signals.

3. The gas sensing device according to claim 1, characterized in that, The detection component includes an interference cancellation module; the interference cancellation module is configured to estimate the vibration interference using an adaptive algorithm with reference to the vibration interference signal, cancel the vibration interference from the mixed signal, and output an initial pure photoacoustic signal.

4. The gas sensing device according to claim 3, characterized in that, The detection component includes a phase-locked demodulation module, which is configured to synchronously detect the initial pure photoacoustic signal, generate a carrier wave with the same frequency and phase as the preset fixed frequency to extract the photoacoustic signal, and output the final pure photoacoustic signal.

5. The gas sensing device according to any one of claims 1-4, characterized in that, The detection component includes a conversion module, which is configured to convert the pure photoacoustic signal based on ambient temperature data and a calibration model to obtain the concentration value of the target gas.

6. The gas sensing device according to claim 1, characterized in that, The modulated light is infrared light, and the center wavelength of the infrared light is the characteristic absorption peak of the target gas.

7. A gas detection method, characterized in that, Based on the gas sensing device as described in any one of claims 1-6; the method includes: Obtain a mixed signal containing the photoacoustic signal and the vibration interference signal; The vibration interference in the mixed signal is canceled by an adaptive algorithm, and the photoacoustic signal matching the preset fixed frequency in the mixed signal is extracted by phase-locked demodulation. After obtaining the pure photoacoustic signal, the concentration value of the target gas is calculated and output.

8. The gas detection method according to claim 7, characterized in that, The method further includes: preprocessing the mixed signal and the vibration interference signal; the preprocessing includes any one of the following: The mixed signal is amplified and filtered to obtain a mixed signal with high-frequency noise suppressed. The vibration interference signal is subjected to low-pass filtering and normalization. The mixed signal and vibration interference signal are sampled synchronously at a certain sampling frequency and converted into digital signals.

9. The gas detection method according to claim 8, characterized in that, The sampling frequency is greater than 100Hz, and the ratio of the sampling frequency to the preset fixed frequency is greater than or equal to 5:

1.

10. The gas detection method according to claim 7, characterized in that, The adaptive algorithm-based cancellation of vibration interference in the mixed signal includes: Using the vibration interference signal as a reference, the vibration interference is estimated through an adaptive algorithm, and the vibration interference is canceled out from the mixed signal to output an initial pure photoacoustic signal.

11. The gas detection method according to claim 10, characterized in that, The step of extracting the photoacoustic signal matching the preset fixed frequency from the mixed signal through phase-locked demodulation to obtain a pure photoacoustic signal includes: The initial pure photoacoustic signal is synchronously detected to generate a carrier wave with the same frequency and phase as the preset fixed frequency to extract the photoacoustic signal and output the final pure photoacoustic signal.

12. The gas detection method according to claim 7, characterized in that, The process of converting the obtained pure photoacoustic signal into the output concentration value of the target gas includes: The concentration value of the target gas is obtained by converting the pure photoacoustic signal based on the ambient temperature data and calibration model.

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