Four-gas intelligent monitoring and acousto-optic vibration alarm device for deep foundation pit and cable well

Abstract

The invention provides a four-gas intelligent monitoring and acousto-optic vibration alarm device for a deep foundation pit and a cable well, and belongs to the technical field of gas detection and safety monitoring. The system comprises an air pressure type height measurement module, a gas acquisition module, a scene adaptive signal processing module, a data operation and control module and a scene special power supply module, wherein the data operation and control module comprises a high-adaptability alarm sub-module, a portable man-machine interaction sub-module, a Bluetooth data transmission sub-module, a data storage unit and a reserved UWB positioning interface. The system can accurately monitor the concentration of various gases in the deep foundation pit and the cable well in real time, such as oxygen, combustible gas, toxic and harmful gas and the like, and performs intelligent judgment according to a preset safety threshold value. Once the gas concentration is detected to be abnormal, the high-adaptability alarm sub-module immediately triggers an acousto-optic vibration alarm to remind field personnel to take safety measures in time, so that safety accidents caused by gas leakage or accumulation are effectively prevented.

Description

Technical Field

[0001] This invention belongs to the field of fault monitoring technology for power metering equipment, specifically relating to a four-gas intelligent monitoring and audible-visual-vibration alarm device for deep foundation pits and cable wells. Background Technology

[0002] With the routine advancement of projects such as power cable well maintenance, deep foundation pit construction, and municipal underground utility tunnel renovation, the operational safety of deep foundation pits, cable wells, and underground utility tunnels, as typical confined spaces, has become a key control point for the power and construction industries. These spaces are characterized by their great depth (deep foundation pits can reach 5-20 meters), strong enclosure (cable wells / utility tunnels are mostly underground closed structures), and poor ventilation. Furthermore, due to the differences in the density of different gases (such as hydrogen sulfide density 1.539 kg / m³, carbon monoxide density 1.250 kg / m³, methane density 0.717 kg / m³, and air density 1.293 kg / m³), a "stratified accumulation" phenomenon is easily formed—methane (CH4), as a gas with a density lower than air, tends to accumulate in the upper layer of the space, hydrogen sulfide (H2S), as a gas with a density higher than air, tends to accumulate in the lower layer of the space, while oxygen (O2) shows an uneven distribution with varying heights.

[0003] Existing gas detection methods have two major drawbacks: Lack of height identification and layered detection capabilities: Traditional detection equipment can perform fixed-point detection, but it cannot identify its own height, let alone perform multi-layered detection based on gas stratification characteristics. In deep foundation pit operations, detecting only the middle layer of gas may miss the risk of excessive hydrogen sulfide (H2S) in the lower layer or the accumulation of methane (CH4) in the upper layer, easily leading to detection blind spots.

[0004] Poor scene adaptability and insufficient detection accuracy: Existing equipment does not fully consider the characteristics of scenes such as drastic temperature and humidity fluctuations in deep foundation pits (temperature difference between the bottom and the wellhead can reach 10-15℃) and strong electromagnetic interference in cable wells (electromagnetic field generated by high-voltage cables), and does not optimize the sampling strategy for gas stratification characteristics, which can easily lead to detection errors; at the same time, the early warning effectiveness is low, with an alarm recognition rate of less than 80% in high noise scenes, and the operation is complicated and the battery life is weak, making it difficult to adapt to the needs of continuous field operations.

[0005] In conclusion, it is particularly important to develop a four-gas intelligent monitoring and audible-visual-vibration alarm device for deep foundation pits and cable wells that features pneumatic height recognition and supports stratified gas detection. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a four-gas intelligent monitoring and audible-visual-vibration alarm device for deep foundation pits and cable wells, which addresses the shortcomings of the prior art.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A four-gas intelligent monitoring and audible-visual-vibration alarm device for deep foundation pits and cable wells includes a pneumatic height measurement module, a gas acquisition module, a scene-adaptive signal processing module, a data processing and control module, and a scene-specific power supply module. The data processing and control module includes a highly adaptable alarm submodule, a portable human-machine interaction submodule, a Bluetooth data transmission submodule, a data storage unit, and a reserved UWB positioning interface. The barometric altitude measurement module and the data processing and control module are communicatively connected. The barometric altitude measurement module and the data processing and control module are used to collect ambient air pressure and temperature data and convert them into real-time altitude information to provide a position reference for layer detection. The gas acquisition module includes a four-gas sensor array and a miniature gas pump, used to collect concentration data of four gases—oxygen (O2), methane (CH4), hydrogen sulfide (H2S), and carbon monoxide (CO)—in a confined space, and is adaptable to scenarios with fluctuating temperature and humidity. The scene-adaptive signal processing module is used to filter and temperature-compensate the collected gas concentration signal to reduce the impact of electromagnetic interference. The data processing and control module has built-in layer detection logic, which is used to receive altitude information and processed gas concentration data, and to complete layer judgment, layer sampling control, layer concentration analysis and alarm trigger judgment. The highly adaptable alarm submodule is used to trigger sound, light, and vibration alarms when the gas concentration exceeds the standard. Furthermore, the scenario-specific power module supplies power to all modules of the device, ensuring continuous operation in the field; The Bluetooth data transmission submodule is used to push the hierarchically associated height and concentration data to the handheld terminal APP. The data storage unit is used to cache hierarchical detection data; Furthermore, the barometric altitude measurement module uses a high-precision barometric pressure sensor with an accuracy of ±0.12 hPa and a temperature measurement range of 40℃~85℃. The barometric pressure sensor communicates with the MCU of the data processing and control module through an I2C or SPI interface, and the power supply is adapted to 3.3V or 5V.

[0008] The height conversion logic of the barometric altimeter module is as follows: by collecting the current ambient air pressure and temperature, setting the reference air pressure and reference altitude of the reference point, and calculating the height difference based on the international standard atmospheric model and temperature compensation. Furthermore, the layer detection logic of the data processing and control module includes: supporting the setting of the number of layers and the height range of each layer through a handheld APP or local buttons; determining the current height layer based on the real-time height value of the height measurement module; determining the entry into a new height layer when the height change is ≥0.5m; automatically triggering the layer sampling marker; and binding and storing the gas concentration data with the height information. It automatically calculates the maximum and average gas concentrations at each altitude level. If the gas concentration at any altitude level exceeds the standard, an alarm is triggered immediately. The "altitude-concentration" correlation data is pushed to the handheld terminal APP via the Bluetooth data transmission submodule, and layered concentration curves are supported for display.

[0009] Furthermore, the detection error of the four gas sensor array is controlled within ±3%FS (before compensation). The micro gas pump is controlled by the I / O port of the data processing and control module, and is started during layer switching. In the non-switching state, it samples intermittently at a preset frequency (1~5Hz).

[0010] Furthermore, the optimization methods for the scene-adaptive signal processing module include: A combination of RC filtering and Kalman filtering is used to reduce the impact of electromagnetic interference on the signal. Temperature data collected by a barometric altitude measurement module is used to compensate for the concentration detection values ​​of the gas sensors, thereby reducing the detection error of the four gases after compensation.

[0011] Furthermore, the highly adaptable alarm submodule includes at least two of the following: sound alarm, light alarm, and vibration alarm. After the alarm is triggered, it supports manual reset via physical button or external terminal.

[0012] Furthermore, the scenario-specific power module uses a lithium battery or a rechargeable battery pack with a battery capacity of ≥4000mAh, a single charge duration of ≥12 hours, and supports 5V / 2A fast charging. It also has overcharge, over-discharge, and short-circuit protection functions.

[0013] Furthermore, the portable human-computer interaction submodule includes an OLED display screen and function buttons.

[0014] 1. This invention possesses advanced identification and layered detection capabilities, eliminating detection blind spots and achieving comprehensive monitoring. By acquiring the device's height in real time through a pneumatic height measurement module, and combining this with the layered detection logic of the data processing and control module, multi-height layer detection can be performed based on gas layering characteristics. In deep foundation pit operations, it can simultaneously detect the accumulation of methane (CH4) in the upper layer, the distribution of oxygen (O2) in the middle layer, and excessive levels of hydrogen sulfide (H2S) in the lower layer, effectively eliminating detection blind spots and increasing the detection coverage from 30% of traditional fixed points to 100%, providing operators with comprehensive gas safety information.

[0015] 2. This invention has strong scenario adaptability and can improve detection accuracy. During use, it fully considers the characteristics of scenarios such as drastic temperature and humidity fluctuations in deep foundation pits and strong electromagnetic interference in cable wells. The scenario-adaptive signal processing module uses a combination of "RC filtering + Kalman filtering" to reduce the impact of electromagnetic interference on the signal. Temperature data collected by the barometric height measurement module is used to compensate for the concentration detection values ​​of the gas sensors, ensuring that the detection error of the four gases before compensation can be controlled within ±3%FS, thus improving detection accuracy.

[0016] 3. This invention improves early warning capabilities. The highly adaptable alarm submodule can simultaneously trigger sound, light, and vibration alarms when gas concentration exceeds the standard. The sound alarm is ≥85dB, the light alarm flashes at a frequency of 1-2Hz, and the vibration alarm vibrates at a frequency of 40-60Hz, ensuring clear identification by operators even in high-noise environments, with an alarm recognition rate ≥99%. Furthermore, after alarm triggering, manual reset via physical buttons or external terminals is supported, making operation convenient.

[0017] 4. This invention is easy to operate and has a long battery life. The portable human-computer interaction submodule includes an OLED display screen and function buttons. The OLED display screen supports switching between two views: "real-time height + current layer concentration" and "concentration statistics for each layer." The function buttons support one-click calibration and one-click start of layer detection, making operation simple and easy to understand. The scene-specific power module uses a lithium battery or rechargeable battery pack with a battery capacity of ≥4000mAh, a single charge battery life of ≥12 hours, and supports 5V / 2A fast charging. It also has overcharge, over-discharge, and short-circuit protection functions, which can meet the needs of continuous field operations. Attached Figure Description

[0018] The present invention will now be described in further detail with reference to the accompanying drawings.

[0019] Figure 1 : This is a structural diagram of the overall module of the device with pneumatic layer detection function of the present invention; Figure 2 : This is a schematic diagram of the hardware connection for the present invention, which includes a pneumatic layer detection function; Figure 3 This is a flowchart illustrating the workflow of the present invention, which includes a pneumatic layer detection function. Figure Labels

[0020] 1. Barometric Altitude Measurement Module; 2. Gas Acquisition Module; 3. Scene-Adaptive Signal Processing Module; 4. Data Calculation and Control Module; 41. Highly Adaptive Alarm Submodule; 42. Portable Human-Machine Interaction Submodule; 43. Bluetooth Data Transmission Submodule; 44. Data Storage Unit; 45. Reserved UWB Positioning Interface; 5. Scene-Specific Power Supply Module. Detailed Implementation

[0021] To better understand the present invention, the content of the invention is further clearly illustrated below with reference to embodiments and accompanying drawings. However, the scope of protection of the present invention is not limited to the embodiments described below. Numerous specific details are set forth in the following description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details.

[0022] See Figure 1 The purpose of this embodiment is to provide a four-gas intelligent monitoring and audible / visual / vibration alarm device for deep foundation pits and cable wells, including a pneumatic height measurement module 1, a gas acquisition module 2, a scene-adaptive signal processing module 3, a data processing and control module 4, and a scene-specific power supply module 5. The data processing and control module 4 includes a highly adaptable alarm submodule 41, a portable human-machine interaction submodule 42, a Bluetooth data transmission submodule 43, a data storage unit 44, and a reserved UWB positioning interface 45; the scene-specific power supply module 5 supplies power to all other modules. The pneumatic height measurement module... 1. The altitude and temperature data are transmitted to the scene-adaptive signal processing module 3 and the data processing and control module 4. The raw signal from the gas acquisition module 2 is first filtered and compensated by the scene-adaptive signal processing module 3, and then transmitted to the data processing and control module 4. After processing, the data processing and control module 4 controls the high-adaptability alarm submodule 41 and the portable human-machine interaction submodule 42 respectively, and pushes the data to the handheld terminal APP through the Bluetooth data transmission submodule 43. At the same time, the data is stored in the data storage unit 44, and a UWB positioning interface 45 is reserved for expanding the positioning function.

[0023] The barometric altitude measurement module 1 and the data processing and control module 4 are connected in communication. By collecting ambient air pressure and temperature data and converting them into real-time altitude information, they provide a position reference for layered detection. See Figure 2 The barometric altitude measurement module 1 uses a high-precision barometric pressure sensor BMP280, with a measurement range of 300~1100hPa, an accuracy of ±0.12hPa, and a temperature measurement range of -40℃~85℃. The barometric pressure sensor is connected to the PB10 (SCL) and PB11 (SDA) pins of the MCU (STM32L431RCT6) of the data processing and control module 4 via an I2C or SPI interface. The power supply terminal is connected to 3.3V or 5V, and the ground terminal is connected to GND.

[0024] The height conversion logic of the pneumatic height measurement module 1 is as follows: Step 1: Collect the current ambient air pressure P (hPa) and temperature T (°C) using BMP280; Step 2: Set the reference pressure P0 and reference height H0 (default 0m) of the reference point (entrance of the confined space); Step 3: Calculate the height difference ΔH, and then obtain the current height using H = H0 + ΔH, where the calculation of ΔH satisfies:

[0025] In the formula, K is the vertical lapse rate of atmospheric temperature (value 0.0065 K / m), R is the dry air gas constant (value 287 J / (kg・K)), g is the gravitational acceleration (value 9.80665 m / s²), and the final height conversion accuracy is ≤ ±0.1 m.

[0026] The gas acquisition module 2 includes a four-gas sensor array and a miniature air pump. The four-gas sensor array is used to collect the concentration data of four gases—oxygen (O2), methane (CH4), hydrogen sulfide (H2S), and carbon monoxide (CO)—within a confined space and is adaptable to scenarios with fluctuating temperature and humidity. The gas acquisition module 2 can perform gas sampling at multiple height levels and perform hierarchical correlation and statistical analysis on the collected gas concentration data. If the gas concentration at any height level exceeds a preset threshold, the high adaptability alarm submodule 41 is triggered. The detection error of the four-gas sensor array is controlled within ±3%FS (before compensation). The miniature air pump is controlled by the I / O port of the data processing and control module 4 and is activated when switching between layers. In the non-switching state, it samples intermittently at a preset frequency (1~5Hz).

[0027] See Figure 2 The analog signals from the original O2, CH4, H2S, and CO sensor arrays are amplified by the operational amplifier LM324 and filtered by the RC filter circuit (10kΩ resistor + 100nF capacitor) before being input to the ADC acquisition pins (PA0~PA3) of the MCU. The micro gas pump (12V) is controlled by the MCU to start and stop via a DC-DC converter, accelerating gas sampling during layer switching. The logic of gas acquisition module 2 is as follows: Sensor array: Four gas sensors with detection error within ±3%FS are selected, respectively adapted for the detection of O2 (such as OXY-A2), CH4 (such as TGS2611), H2S (such as H2S-B4), and CO (such as CO-B4), with a sensor response time ≤100ms; Sampling control: Built-in micro air pump, controlled by MCU IO port to start and stop. In non-layer switching state, it samples intermittently at 1~5Hz. When layer switching occurs, it is forced to start for 1 second to ensure sampling efficiency. Structural design: The sampling port adopts a dustproof and waterproof structure, equipped with a 100-mesh filter to prevent dust and soil blockage, making it suitable for harsh outdoor environments.

[0028] The scene-adaptive signal processing module 3 is used to filter and temperature compensate the collected gas concentration signal to reduce the impact of electromagnetic interference and optimize detection accuracy. The logic of the scene-adaptive signal processing module 3 is as follows: Filtering: A combination of RC filtering and Kalman filtering is used. RC filtering is used to suppress high-frequency electromagnetic interference, while Kalman filtering is used to eliminate signal noise and improve data stability. Temperature compensation: The gas concentration value is corrected using real-time temperature data collected by the barometric altitude measurement module 1 and a calibrated temperature coefficient. The compensation formula is as follows (taking the H2S sensor as an example):

[0029] Where C_comp is the compensated concentration, C_raw is the original concentration, K_t is the temperature coefficient (0.002~0.003, calibrated experimentally), T is the real-time temperature, and T0 is the sensor standard temperature (25℃). Anti-interference design: The signal transmission line uses shielded wire, and the circuit board adds a grounding shielding layer to effectively reduce the impact of strong electromagnetic interference in scenarios such as cable wells.

[0030] Reference Figure 2 Among the newly added hardware: Miniature air pump control: When the PA8 pin of the MCU outputs a high level, the relay is activated to start the air pump. When the device moves to a new altitude layer (altitude change ≥ 0.5m), the air pump starts for 1 second to accelerate sampling, ensuring that the gas at the new altitude layer quickly enters the sensor. Temperature compensation correlation: The temperature data collected by BMP280 (accuracy ±1℃) is transmitted to the MCU in real time to correct the concentration calculation of O2 / H2S / CO / CH4 sensors (for example, the concentration deviation of H2S sensor at 25℃ and 35℃ corresponding to the same voltage is ≤2%, which can be corrected to ≤0.5% through temperature compensation).

[0031] The data processing and control module 4 has a built-in layer detection logic, which is used to receive height information and processed gas concentration data, and complete layer judgment, layer sampling control, layer concentration analysis and alarm trigger judgment. If the gas concentration of any height layer exceeds the preset threshold, the layer detection logic will trigger the high-adaptability alarm submodule 41. The highly adaptable alarm submodule 41 is used to trigger sound, light and vibration alarms when the gas concentration exceeds the standard. It adopts an 85dB sound alarm + 1Hz flashing light alarm + 50Hz vibration alarm to adapt to high noise scenarios. The scene-specific power module 5 supplies power to all modules of the device. It uses a 5000mAh lithium battery with 12 hours of battery life, supports fast charging in the field, and ensures battery life during field operations. See Figure 2 The original buzzer (85dB), red LED indicator (1Hz flashing), and vibration motor (50Hz) are driven by the MCU's PB0, PB1, and PB2 pins, respectively; the OLED display communicates with the MCU via the I2C interface, and three function buttons (layer setting, confirmation, and calibration) are connected to the MCU's GPIO pins to realize human-machine interaction.

[0032] The Bluetooth data transmission submodule 43 is used to push the hierarchically associated height and concentration data to the handheld terminal APP. The data storage unit 44 is used to cache stratified detection data, caching at least 7 days of stratified data.

[0033] The core functions of data processing and control module 4 include: Layer parameter settings: Supports setting "number of layers" and "height range of each layer" via handheld APP or local button (e.g., deep foundation pit scenario is divided into 3 layers by default: lower layer 0~5m, middle layer 5~10m, upper layer 10~15m). Layered sampling control: The MCU determines the current height layer based on the real-time height value of the height measurement module. If it moves to a new height layer (such as moving from the lower layer 5m to the middle layer 5.1m), it automatically triggers the "layered sampling mark" to bind and store the gas concentration data of that height layer with the height information. Stratified concentration analysis: Automatically calculates the maximum / average concentration of each layer, such as the average value of H2S in the lower layer and the maximum value of CH4 in the upper layer. If the concentration of any layer exceeds the standard, an alarm will be triggered. Layered data push: The height and concentration correlation data are pushed to the handheld APP via Bluetooth module, and the layered concentration curves (such as height on the X-axis and concentration on the Y-axis) are displayed to intuitively present the gas layered distribution.

[0034] The hierarchical detection logic of data processing and control module 4 includes: Layer parameter configuration: Supports setting the number of layers (2~5 layers), the height range of each layer, and the layer switching threshold (0.3m~2m) through a portable human-computer interaction module or external terminal. Layering judgment: Real-time comparison between the current height and the set height range. If the height change exceeds the layer switching threshold, it is determined to enter the new height layer. Layered sampling control: When entering a new altitude layer, the gas acquisition module 2 is automatically triggered to accelerate sampling, with a sampling response time of ≤1 second; Stratified analysis: The maximum and average gas concentrations at each altitude level are statistically analyzed, and the test is deemed "qualified" only when the gas concentrations at each altitude level meet the safety threshold.

[0035] The optimization method of the scene-adaptive signal processing module 3 is to use a combination of "RC filtering + Kalman filtering" to reduce the impact of electromagnetic interference on the signal. The temperature data collected by the barometric altitude measurement module 1 is used to perform temperature compensation on the concentration detection value of the gas sensor. After compensation, the detection error of the four gases is reduced and controlled within ±3%FS.

[0036] The highly adaptable alarm submodule 41 includes at least two of the following: sound alarm, light alarm, and vibration alarm. The sound alarm has a decibel level of ≥85dB, the light alarm has a flashing frequency of 1~2Hz, and the vibration alarm has a vibration frequency of 40~60Hz. After the alarm is triggered, it supports manual reset via physical button or external terminal, and the alarm recognition rate is ≥99%.

[0037] The scenario-specific power module 5 uses a lithium battery or a rechargeable battery pack with a battery capacity of ≥4000mAh, a single charge duration of ≥12 hours, and supports 5V / 2A fast charging. It also features overcharge, over-discharge, and short-circuit protection. The portable human-computer interaction submodule 42 includes an OLED display screen and function buttons. The OLED display screen supports switching between two views: "real-time height + current layer concentration" and "concentration statistics of each layer". The function buttons support one-click calibration and one-click start of layer detection. The handheld terminal APP supports exporting layer concentration reports in Excel format, which includes timestamps, height values, concentrations of four gases and information on the current height layer, and automatically generates statistical data on concentration of each height layer.

[0038] The cache duration of the data storage unit 44 can be set from 3 to 30 days, and it supports "priority storage of abnormal data" (automatic marking and priority retention when the gas concentration exceeds the standard); the external terminal (handheld APP or PC) supports exporting layered detection reports in Excel or CSV format. The reports include information such as timestamp (accurate to the second), height / horizontal position, concentration of four gases (oxygen, methane, hydrogen sulfide, carbon monoxide), layer, and whether the standard is exceeded.

[0039] Steps for using layered detection in the field (taking a deep foundation pit scenario as an example) (1) Preset layered parameters (before operation) 1. At the head of the deep foundation pit, press and hold the "Layered Setting" button (new button, connected to MCU PB12 pin) for 3 seconds. The display will show "Layered Setting Mode". 2. Use the "Up / Down" button (reuse the original calibration / reset button) to set the number of layers (default 3 layers) and the height range of each layer: lower layer: 0~5m, middle layer: 5~10m, upper layer: 10~15m; 3. Press the "Confirm" button (reuse the power button) to save the layer parameters and return to the main interface.

[0040] (2) Layered detection operation (in operation) 1. Reference point calibration: Keep the device stationary at the wellhead for 10 seconds. The display screen will show "Reference point calibration completed, H0=0m, P0=1013hPa". 2. Layered movement detection: The operator slowly lowered the device from the wellhead (H=0m, lower layer) to the bottom of the pit, updating the device's height and concentration every second during the process; When the altitude increases from 4.9m to 5.1m (entering the middle layer), the display screen will indicate "Entering the middle layer (5~10m), accelerating sampling", and the air pump will start and then stop after 1 second; Upon reaching the bottom (H=15m, upper layer), the device automatically calculates the concentration of each layer: for example, "lower layer H2S=8ppm, middle layer O2=20.1%VOL, upper layer CH4=3%LEL"; 3. Abnormal Handling: If the H2S concentration rises to 12ppm (exceeding the standard) when the lower layer H=3m, the device will immediately activate the triple alarm, the display screen will show "H2S in the lower layer exceeds the standard! Current 12ppm", the APP will push the alarm information simultaneously, and the operators will stop lowering and evacuate.

[0041] (3) Data export after the task 1. Data export preparation: After the operation is completed, bring the device back to the ground, keep it powered on, and connect it to the handheld APP via Bluetooth (supports Android / iOS systems). 2. Layered Data Selection: In the "Data Management" interface of the APP, select "Export Layered Data" to filter by "Operation Time Period" (e.g., 2025-XX-XX 08:00-12:00) and "Target Height Layer" (e.g., the lower layer 0~5m, all layers); 3. Data Format and Content: Exported data is in Excel format, containing 7 types of information: "timestamp (accurate to second), height value (m, rounded to 1 decimal place), O2 concentration (%VOL), CH4 concentration (%LEL), H2S concentration (ppm), CO concentration (ppm), and height layer". At the same time, it automatically generates concentration statistics reports for each height layer (maximum value, minimum value, average value, number of times exceeding the standard). 4. Data Usage: The exported layered data can be used for post-operation safety analysis (such as determining the main accumulation area of ​​H2S) and hazard tracing (such as the cause of fluctuations in the upper layer CH4 concentration over a certain period of time), which complies with the "operation data retention" requirement in the "Regulations on Safety Work for Confined Space Operations of State Grid Corporation of China".

[0042] (4) Special scenario operation (taking underground utility tunnel as an example) Underground utility tunnels are typically flat spaces (usually 2-3 meters high and hundreds of meters long), and gas stratification is primarily characterized by "lateral regions" (such as concentration differences between the tunnel entrance and middle sections). Therefore, adjustments to the stratification detection process are necessary. 1. Layer parameter adjustment: Change "height layering" to "horizontal distance layering" through the APP, set the reference point to the entrance of the utility tunnel (H0=0m, corresponding distance 0m), and set the layering interval to "0~50m (near entrance section), 50~100m (middle section), 100~150m (far entrance section)"; 2. Height-Distance Conversion: Using the device's moving speed (the walking speed of the operator is about 1m / s) and time, the slight height changes of the height measurement module (the undulation of the pipe gallery ground ≤ 0.3m) are corrected to the lateral distance (distance = moving speed × time) to ensure accurate layer judgment; 3. Sampling optimization: The ventilation inside the pipe gallery is poor. Set "forced sampling every 20m" (regardless of whether the layer is switched). The air pump starts for 2 seconds to ensure that the gas in each horizontal area is collected.

[0043] See Figure 3 The workflow is as follows: Power-on startup and initialization: After the device is powered on, it completes system initialization (configuration of GPIO, communication interface, ADC, etc.) and performs reference calibration on the BMP280 sensor.

[0044] Reference point acquisition: At the entrance of a deep foundation pit or cable well, statically collect the air pressure P0 and the reference height H0=0m at the reference point as the basis for height conversion.

[0045] Sensor preheating and gas pump initialization: The gas sensor preheats for 30 seconds, and the miniature gas pump completes initialization to ensure sampling response speed.

[0046] Cyclic synchronous sampling: Altitude conversion: Based on the ratio of real-time air pressure P to reference air pressure P0, and combined with real-time temperature T, the current altitude H is converted using the international standard atmospheric model formula.

[0047] Layer determination: Compare the current height H with the preset layer interval (such as 0~5m, 5~10m, 10~15m) to determine whether to enter a new height layer.

[0048] Sampling control: If a new altitude layer is entered, the MCU controls the air pump to start for 1 second to accelerate sampling; if not, sampling is performed intermittently at a frequency of 1~5Hz.

[0049] Signal processing and concentration calculation: The collected gas signal is processed by "RC filtering + Kalman filtering" and temperature compensation to obtain accurate concentration values.

[0050] Data storage and alarm judgment: The "height H, concentration, and time" are stored together, and it is determined whether the concentration of each layer exceeds the preset threshold (such as O2≤19.5%VOL, H2S≥10ppm, etc.).

[0051] Alarm and data push: If the concentration exceeds the standard, a triple alarm of sound, light and vibration will be triggered immediately, and the OLED will display "XX layer XX gas exceeds the standard"; if the concentration does not exceed the standard, the OLED will display the current layer height and concentration, and the Bluetooth module will simultaneously push the layer data to the handheld terminal APP to generate the layer concentration curve.

[0052] The device supports a lateral distance layering mode, which corrects minute height changes in the height measurement module to lateral distances based on the operator's movement speed and time, making it suitable for flat spaces such as underground utility tunnels. In lateral layering mode, it also supports forced activation of the air pump for sampling for 2 seconds every 20m.

[0053] The device operates in a temperature range of -10℃ to 50℃, has an IP65 protection rating, and is equipped with a UWB positioning interface 45 for mobile operation linkage, making it suitable for confined space operation scenarios such as deep foundation pits, cable wells, and underground pipe corridors.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A four-gas intelligent monitoring and audible / visual / vibration alarm device for deep foundation pits and cable wells, characterized in that, It includes a barometric altitude measurement module, a gas acquisition module, a scene-adaptive signal processing module, a data processing and control module, and a scene-specific power supply module. The data processing and control module includes a highly adaptable alarm submodule, a portable human-machine interaction submodule, a Bluetooth data transmission submodule, a data storage unit, and a reserved UWB positioning interface. The barometric altitude measurement module and the data processing and control module are communicatively connected. The barometric altitude measurement module and the data processing and control module are used to collect ambient air pressure and temperature data and convert them into real-time altitude information to provide a position reference for layer detection. The gas acquisition module includes a four-gas sensor array and a miniature gas pump. The four-gas sensor array is used to acquire the concentration data of four gases—oxygen, methane, hydrogen sulfide, and carbon monoxide—in a confined space and is adaptable to scenarios with fluctuating temperature and humidity. The scene-adaptive signal processing module is used to filter and temperature-compensate the collected gas concentration signal to reduce the impact of electromagnetic interference. The data processing and control module has built-in layer detection logic, which is used to receive altitude information and processed gas concentration data, and to complete layer judgment, layer sampling control, layer concentration analysis and alarm trigger judgment. The highly adaptable alarm submodule is used to trigger sound, light, and vibration alarms when the gas concentration exceeds the standard.

2. The four-gas intelligent monitoring and audible / visual vibration alarm device for deep foundation pits and cable wells according to claim 1, characterized in that, The dedicated power module for the specific scenario provides power to all modules of the device, ensuring continuous operation in the field. The Bluetooth data transmission submodule is used to push the hierarchically associated height and concentration data to the handheld terminal APP. The data storage unit is used to cache hierarchical detection data.

3. The four-gas intelligent monitoring and audible / visual vibration alarm device for deep foundation pits and cable wells according to claim 2, characterized in that, The barometric altitude measurement module uses a high-precision barometric pressure sensor with an accuracy of ±0.12 hPa and a temperature measurement range of 40℃~85℃. The barometric pressure sensor communicates with the MCU of the data processing and control module through an I2C or SPI interface, and the power supply is adapted to 3.3V or 5V.

4. The four-gas intelligent monitoring and audible / visual vibration alarm device for deep foundation pits and cable wells according to claim 3, characterized in that, The layer detection logic of the data processing and control module includes: supporting the setting of the number of layers and the height range of each layer through a handheld APP or local buttons; determining the current height layer based on the real-time height value of the height measurement module; determining the entry into a new height layer when the height change is ≥0.5m; automatically triggering the layer sampling marker; and binding and storing the gas concentration data with the height information. It automatically calculates the maximum and average gas concentrations at each altitude level. If the gas concentration at any altitude level exceeds the standard, an alarm is triggered immediately. The correlation data between altitude and concentration is pushed to the handheld terminal APP via the Bluetooth data transmission submodule, and layered concentration curves are supported for display.

5. The four-gas intelligent monitoring and audible / visual vibration alarm device for deep foundation pits and cable wells according to claim 4, characterized in that, The detection error of the four gas sensor array is controlled within ±3%FS. The micro gas pump is controlled by the I / O port of the data processing and control module. It is started when the layer is switched, and when not switched, it is intermittently sampled at a preset frequency of 1~5Hz.

6. The four-gas intelligent monitoring and audible / visual vibration alarm device for deep foundation pits and cable wells according to claim 5, characterized in that, The scenario-adaptive signal processing module uses a combination of RC filtering and Kalman filtering to reduce the impact of electromagnetic interference on the signal.

7. The four-gas intelligent monitoring and audible / visual vibration alarm device for deep foundation pits and cable wells according to claim 6, characterized in that, The highly adaptable alarm submodule includes at least two of the following: sound alarm, light alarm, and vibration alarm. After the alarm is triggered, it supports manual reset via physical button or external terminal.

8. The four-gas intelligent monitoring and audible / visual vibration alarm device for deep foundation pits and cable wells according to claim 7, characterized in that, The scenario-specific power module uses a lithium battery or a rechargeable battery pack with a battery capacity of ≥4000mAh, a single charge duration of ≥12 hours, and supports 5V / 2A fast charging. It also has overcharge, over-discharge, and short-circuit protection functions.

9. The four-gas intelligent monitoring and audible / visual vibration alarm device for deep foundation pits and cable wells according to claim 8, characterized in that, The portable human-computer interaction submodule includes an OLED display screen and function buttons.

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