Negative drift self-correction system for gas sensors

Abstract

The application provides a negative drift self-correction system of a gas sensor, which comprises a power supply module, a hardware circuit module, a gas sensor module and a program algorithm module; the power supply module is electrically connected with the hardware circuit module and the gas sensor module respectively to provide required electric energy for the hardware circuit module and the gas sensor module; the hardware circuit module is used for collecting signals of the gas sensor module; the program algorithm module is electrically connected with the hardware circuit module, used for receiving the signals of the gas sensor module collected by the hardware circuit and performing correction processing, so that the zero point correction mode of the sensor is changed, the production cost of the manufacturer and the use cost of the user are saved, the sensor can independently operate in a work site, the zero point can be automatically adjusted, the precision error caused by the traditional software shielding mode is optimized, and the mode of automatically adjusting the zero point makes it unnecessary to separately provide professional equipment to dispatch a special officer to maintain the site.

Description

Technical Field

[0001] This invention belongs to the field of gas sensor calibration technology, and specifically relates to a negative drift self-calibration system for a gas sensor. Background Technology

[0002] Currently, gas sensors are conversion devices that utilize various physical and chemical properties to convert the composition or concentration of a specific gas into an electrical signal according to a certain rule. With societal development, the demand for gas sensors across various industries is increasing, leading to the development of diverse types, including catalytic combustion, electrochemical, thermal conductivity, infrared, and semiconductor types. Furthermore, technological advancements are placing increasingly higher performance requirements on gas sensors. In practical applications, the zero point of a gas sensor is often unstable due to its own device characteristics or the operating environment, exhibiting a negative drift. To accurately monitor the surrounding gases, gas sensors must ensure zero-point stability and correct for this negative drift.

[0003] However, current technologies for handling zero-point drift in gas sensors include hardware circuit compensation, software shielding, and manual intervention. Circuit compensation involves using other electronic devices in the circuit to compensate and correct the original output signal. This method is not suitable for mass production because the characteristics of each gas sensor are not completely consistent. Compensating each gas sensor requires adjusting the parameters of the compensation device individually, wasting a lot of manpower and resources. Software shielding does not process negative drift values ​​and only extracts data output above zero. The consequence of this is that over time, the linear characteristics of the sensor deviate significantly, and its measurement values ​​are unreliable. Manual intervention refers to periodically dispatching personnel to re-zero and calibrate the gas sensors. This requires personnel to be familiar with the debugging and operation methods of all currently used gas sensors and to be equipped with professional debugging equipment. In actual use, the sensors are widely distributed, requiring multiple personnel or a single person to travel around, resulting in low calibration efficiency. Summary of the Invention

[0004] This invention proposes a negative drift self-calibration system for gas sensors, which solves the problems in the prior art.

[0005] The technical solution of the present invention is implemented as follows: a negative drift self-calibration system for a gas sensor, comprising a power supply module, a hardware circuit module, a gas sensor module, and a program algorithm module;

[0006] The power supply module is electrically connected to the hardware circuit module and the gas sensor module respectively, providing the necessary power to the hardware circuit module and the gas sensor module.

[0007] The hardware circuit module is used to acquire signals from the gas sensor module;

[0008] The program algorithm module is electrically connected to the hardware circuit module and is used to receive signals from the gas sensor module collected by the hardware circuit and perform correction processing.

[0009] In a preferred embodiment, the program algorithm module includes a signal input terminal, a resistor electrically connected to the signal input terminal, the other end of the resistor electrically connected to the ADC function pin of the MCU, the fourth pin of the MCU grounded, a capacitor electrically connected to the eighth pin of the MCU, the other end of the capacitor grounded, and a power supply voltage input terminal electrically connected to the capacitor.

[0010] In a preferred embodiment, the raw signal of the gas sensor module enters the MCU after passing through the signal input terminal and the protection resistor. The MCU filters the signal multiple times and takes the average value, then compares it with the initial zero point. If the value is less than the initial zero point, the current zero point value is subtracted by 1 and stored.

[0011] In a preferred embodiment, the MCU acquires the signal AD value of a gas sensor module every 0.5s and puts it into "Buffer 1" with a length of 20. Then, it copies the data in "Buffer 1", sorts it, and takes the average of the middle 12 data points, which is then put into "Buffer 2" with a length of 120. After copying the data in "Buffer 2" and sorting it, it determines the difference between the maximum and minimum values. If the difference is less than the AD value corresponding to ▲0.1% gas concentration, it takes the average of the middle 80 data points. If this average is less than the initial zero point value, it subtracts 1 from the current actual zero point value and stores it.

[0012] In a preferred embodiment, "Cache 1" stores the latest 20 data entries, and "Cache 2" stores the latest 120 data entries.

[0013] In a preferred embodiment, the resistance of the resistor is 220Ω and the capacitance is 0.1μF.

[0014] After adopting the above technical solution, the beneficial effects of the present invention are:

[0015] 1. The zero-point drift problem can basically be solved using only software processing, with minimal dependence on hardware circuitry;

[0016] 2. It uses a successive approximation method, rather than direct masking, and does not display negative numbers;

[0017] 3. Automatic calibration eliminates the need for manual zero-point calibration after being put into use;

[0018] 4. Saves manufacturers' production costs and reduces users' usage costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a circuit diagram of the signal acquisition section in this invention;

[0021] Figure 2 This is a flowchart of the present invention.

[0022] In the diagram, R3 is a resistor; C2 is a capacitor; GND is ground; VCC is the power supply voltage input terminal; and Signal is the signal input terminal. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figures 1-2 As shown, a negative drift self-calibration system for a gas sensor solves the problems in the prior art.

[0025] The technical solution of the present invention is implemented as follows: a negative drift self-calibration system for a gas sensor, comprising a power supply module, a hardware circuit module, a gas sensor module, and a program algorithm module;

[0026] The power supply module is electrically connected to the hardware circuit module and the gas sensor module respectively, providing the necessary power to the hardware circuit module and the gas sensor module.

[0027] The hardware circuit module is used to acquire signals from the gas sensor module;

[0028] The program algorithm module is electrically connected to the hardware circuit module and is used to receive signals from the gas sensor module collected by the hardware circuit and perform correction processing.

[0029] The power supply module is electrically connected to the gas sensor module and hardware circuit module to provide the energy required for normal operation. The hardware circuit module collects the signal from the gas sensor and transmits it to the program algorithm module for processing. In the program algorithm module, the raw gas sensor signal passes through a protective resistor before entering the MCU. The MCU filters the signal multiple times, takes the average value, and compares it with the initial zero point. If the current value is less than the initial zero point, the current zero point value is subtracted by 1 and stored. This changes the zero point correction method of the sensor, saving production costs for manufacturers and operating costs for users. The sensor can operate autonomously in the working environment and automatically adjust its zero point, optimizing the accuracy errors caused by traditional software shielding methods. The automatic zero point adjustment method eliminates the need for separate professional equipment and dispatched personnel for maintenance in the field.

[0030] The program algorithm module includes a signal input terminal (Signal), which is electrically connected to a resistor R3. The other end of the resistor is electrically connected to the ADC function pin of the MCU. The fourth pin of the MCU is grounded, and the eighth pin of the MCU is electrically connected to a capacitor C2, the other end of which is grounded (GND). A power supply voltage input terminal is also electrically connected to the capacitor. The raw signal from the gas sensor module enters the MCU after passing through the signal input terminal (Signal) and the protection resistor R3. The MCU filters the signal multiple times, takes the average value, and compares it with the initial zero point. If the current value is less than the initial zero point, the current zero point value is subtracted by 1 and stored. The MCU acquires the AD value of a gas sensor module every 0.5 seconds and stores it in a 20-byte buffer ("Buffer 1"). Then, it copies and sorts the data in "Buffer 1," takes the average of the middle 12 data points, and stores this average in a 120-byte buffer ("Buffer 2"). The MCU then copies and sorts the data in "Buffer 2," and determines the difference between the maximum and minimum values. If this difference is less than the AD value corresponding to a 0.1% gas concentration, it takes the average of the middle 80 data points. If this average is less than the initial zero-point value, it subtracts 1 from the current actual zero-point value and stores it. "Buffer 1" stores the latest 20 data points, and "Buffer 2" stores the latest 120 data points. The resistor R3 has a resistance of 220Ω, and the capacitor C2 has a capacitance of 0.1μF.

[0031] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two elements; they can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0032] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A negative drift self-calibration system for a gas sensor, characterized in that, It includes a power supply module, a hardware circuit module, a gas sensor module, and a program algorithm module; The power supply module is electrically connected to the hardware circuit module and the gas sensor module respectively, providing the necessary power to the hardware circuit module and the gas sensor module. The hardware circuit module is used to acquire signals from the gas sensor module; The program algorithm module is electrically connected to the hardware circuit module and is used to receive signals from the gas sensor module collected by the hardware circuit and perform correction processing. The program algorithm module includes a signal input terminal, a resistor electrically connected to the signal input terminal, the other end of the resistor electrically connected to the ADC function pin of the MCU, the fourth pin of the MCU grounded, a capacitor electrically connected to the eighth pin of the MCU, the other end of the capacitor grounded, and a power supply voltage input terminal electrically connected to the capacitor. The raw signal from the gas sensor module enters the MCU after passing through the signal input terminal and the protection resistor. The MCU filters the signal multiple times and takes the average value, then compares it with the initial zero point. If the value is less than the initial zero point, the current zero point value is subtracted by 1 and stored. The MCU acquires the signal AD value of a gas sensor module every 0.5s and puts it into "Buffer 1" with a length of 20. Then, it copies the data in "Buffer 1", sorts it, and takes the average of the middle 12 data points, which is put into "Buffer 2" with a length of 120. Then, it copies the data in "Buffer 2", sorts it, and judges the difference between the maximum and minimum values. If the difference is less than the AD value corresponding to ▲0.1% gas concentration, it takes the average of the middle 80 data points. If this average value is less than the initial zero point value, it subtracts 1 from the current actual zero point value and stores it. The resistor has a resistance of 220Ω and the capacitor has a capacitance of 0.1μF.

2. The negative drift self-calibration system for a gas sensor according to claim 1, characterized in that, "Cache 1" stores the latest 20 data entries, and "Cache 2" stores the latest 120 data entries.

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