Self-adaptive temperature compensation high-precision strain gauge and measuring method

Abstract

The invention relates to the technical field of precision measurement and intelligent sensors, and discloses a self-adaptive temperature compensation high-precision strain gauge and a measurement method.The self-adaptive temperature compensation high-precision strain gauge comprises an insulating substrate, a strain sensitive grid and an intelligent semiconductor temperature sensor are integrated on the insulating substrate, and the intelligent semiconductor temperature sensor is arranged close to the end of the strain sensitive grid; the intelligent semiconductor temperature sensor internally comprises a temperature sensing unit and a nonvolatile storage unit; s100, the digital communication interface or the low-power-consumption wireless module is used for reading a pre-stored compensation coefficient exclusive to a strain gauge from a nonvolatile storage unit of the intelligent semiconductor temperature sensor; s200, synchronously acquiring a strain signal from the strain sensitive grid and a real-time temperature signal from the intelligent semiconductor temperature sensor; and S300, performing mathematical operation on the acquired strain signal by using the temperature compensation coefficient read in the S100 and the real-time temperature signal acquired in the S200 to compensate drift caused by the temperature so as to obtain a real strain value.

Description

Technical Field

[0001] This invention relates to the technical field of precision measurement and intelligent sensors, and more specifically, to an adaptive temperature-compensated high-precision strain gauge and measurement method. Background Technology

[0002] One of the core challenges of strain gauge measurement is eliminating temperature drift. Traditional temperature compensation techniques, such as bridge compensation, self-compensating strain gauges using specific materials, or simply attaching passive temperature sensors (such as platinum resistance thermometers or thermistors) externally, all have inherent limitations.

[0003] A fundamental flaw in these traditional methods is that they all rely on a universal or batch-averaged temperature compensation model. For example, even the highest quality strain gauges possess unique characteristics in terms of temperature coefficient of resistance (TCR) and zero-point drift due to subtle differences in the microstructure of the metal foil and the manufacturing process. Traditional methods cannot provide a dedicated, precise compensation scheme for each strain gauge. Externally attached passive sensors can only provide temperature data but cannot carry the characteristic information of the strain gauge itself, resulting in compensation algorithms that can only apply a one-size-fits-all approach, making it difficult to achieve the maximum accuracy.

[0004] In fields demanding extreme precision, such as aerospace, precision instruments, and long-term structural health monitoring, residual temperature errors caused by individual differences are unacceptable. Therefore, the industry urgently needs a technology that can overcome the bottleneck of "standardized compensation" and achieve personalized and precise compensation for each strain gauge. Summary of the Invention

[0005] To address the aforementioned technical problems in related technologies, this invention provides an adaptive temperature-compensated high-precision strain gauge and measurement method, which can solve the above problems.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is implemented as follows: An adaptive temperature-compensated high-precision strain gauge includes an insulating substrate on which a strain-sensitive grid and a smart semiconductor temperature sensor are integrated. The smart semiconductor temperature sensor is disposed adjacent to the end of the strain-sensitive grid and includes a temperature sensing unit and a non-volatile storage unit.

[0007] Furthermore, the insulating substrate is a polyimide substrate, a silicon-based substrate, or a ceramic substrate.

[0008] Furthermore, the strain-sensitive gate is a constantan strain-sensitive gate fabricated on the insulating substrate by a photolithography etching process.

[0009] Furthermore, the intelligent semiconductor temperature sensor is integrated onto the insulating substrate using a surface mount technology or a flip-chip bonding process.

[0010] Furthermore, the insulating substrate is provided with a plurality of pads for connecting the strain-sensitive gate and the smart semiconductor temperature sensor, and the smart semiconductor temperature sensor also includes a digital communication interface.

[0011] Furthermore, a low-power wireless module for connecting the strain-sensitive grid and the smart semiconductor temperature sensor, as well as a self-powered energy module for providing power, are disposed on the insulating substrate.

[0012] Furthermore, the intelligent semiconductor temperature sensor also includes an online self-calibration module.

[0013] A measurement method for an adaptive temperature-compensated high-precision strain gauge includes the following steps: S100. Using the digital communication interface or low-power wireless module, read the pre-stored, strain gauge-specific compensation coefficients from the non-volatile storage unit of the smart semiconductor temperature sensor. S200, synchronously acquire strain signals from the strain-sensitive grid and real-time temperature signals from the intelligent semiconductor temperature sensor; S300: Using the temperature compensation coefficient read in S100 and the real-time temperature signal acquired in S200, mathematical operations are performed on the acquired strain signal to compensate for the drift caused by temperature, thereby obtaining the true strain value.

[0014] Furthermore, the compensation coefficient mentioned in S100 is calculated and written into the non-volatile storage unit after the strain gauge is calibrated by actual temperature test on the strain sensitive grid on each strain gauge before it leaves the factory, and each strain gauge has a unique ID.

[0015] Furthermore, the online self-calibration module periodically outputs a known minute current to the strain-sensitive grid, and obtains the relationship between the real-time resistance of the strain gauge and the temperature through reverse calculation. At each set interval, it automatically compares the relationship between the resistance of the strain gauge and the temperature calibrated before leaving the factory, corrects the compensation coefficient according to the comparison deviation, and updates it to the non-volatile storage unit.

[0016] The beneficial effects of this invention are as follows: Each strain gauge in this application has a unique digital ID and factory calibration data. By adopting the method of "one gauge, one code, one code, one policy", the compensation error caused by individual manufacturing differences is fundamentally eliminated, the accuracy of strain measurement is raised to a whole new level, and the quality control and data reliability in key applications such as aviation, defense, and major projects are greatly improved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

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

[0019] Figure 1 This is a simplified structural diagram of an adaptive temperature compensation high-precision strain gauge according to an embodiment of the present invention. Detailed Implementation

[0020] 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0021] like Figure 1 As shown, this invention discloses an adaptive temperature-compensated high-precision strain gauge, comprising an insulating substrate 1, on which a strain-sensitive grid 2 and a smart semiconductor temperature sensor 3 are integrated. The smart semiconductor temperature sensor 3 is disposed adjacent to the end of the strain-sensitive grid 2, and internally includes a temperature sensing unit and a non-volatile storage unit. A measurement method for the adaptive temperature-compensated high-precision strain gauge is also disclosed, comprising the following steps: S100, using the digital communication interface or low-power wireless module, reading pre-stored, strain gauge-specific compensation coefficients from the non-volatile storage unit of the smart semiconductor temperature sensor 3; S200, synchronously acquiring strain signals from the strain-sensitive grid 2 and real-time temperature signals from the smart semiconductor temperature sensor 3; S300, using the temperature compensation coefficients read in S100 and the real-time temperature signals acquired in S200, performing mathematical operations on the acquired strain signals to compensate for temperature-induced drift, thereby obtaining the true strain value.

[0022] In a specific embodiment of this application, the insulating substrate 1 may be a polyimide substrate. A 120Ω constantan strain-sensitive gate is fabricated on the polyimide substrate by photolithography etching. At the end of the constantan strain-sensitive gate, a smart semiconductor temperature sensor 3 with a built-in non-volatile memory unit (such as EEPROM or Flash, for writing and permanently storing data before leaving the factory) and a temperature sensing unit (for accurately measuring the temperature at its location) is integrated by surface mount technology (SMT) or flip-chip bonding. The smart semiconductor temperature sensor 3 may optionally include a microprocessor unit for controlling data reading and writing and communication.

[0023] Furthermore, the aforementioned step-by-step process of "photolithography etching of the sensitive gate + SMT / flip-chip bonding of the smart sensor" may have two problems: Although the sensor and the sensitive gate are on the same substrate, they are still "discrete devices," and there is a slight temperature difference between them (especially in scenarios with rapid temperature changes), resulting in "temperature asynchrony" between temperature measurement and strain sensing; SMT / flip-chip bonding sensors have a certain volume (usually ≥1mm×1mm), which will occupy too much space in miniaturization scenarios (such as stress monitoring of microelectronic chip packaging, and small components of medical devices), and may even affect the deformation of the measured device. Therefore, the variable sensitive gate 2 and the smart semiconductor temperature sensor 3 can be integrated using MEMS technology. The specific steps are as follows: on a silicon-based or ceramic substrate, a constantan / nickel-chromium sensitive gate is fabricated using sputtering + photolithography; in the same substrate area next to the sensitive gate, the core module (temperature measurement unit, EEPROM, communication interface) of the smart sensor is directly fabricated using CMOS-compatible processes (such as ion implantation, metallization), achieving integration without "discrete devices."

[0024] In a specific embodiment of this application, to enable communication between the strain-sensitive gate 2 and the intelligent semiconductor temperature sensor 3 and an external data acquisition system (DAQ), a digital communication interface (such as I2C, SPI, or a single-bus protocol interface) can be set inside the intelligent semiconductor temperature sensor 3, and several pads can be set on the insulating substrate 1, including two dedicated pads for the strain-sensitive gate, which export the resistance change (analog signal) generated by the mechanical deformation of the strain-sensitive gate 2 and connect it to the analog channel of the external data acquisition system (DAQ). It also includes 3 to 4 dedicated pads for the intelligent temperature sensor (used for VCC, GND, SDA, and SCL, respectively). Among them, the VCC (positive power supply) and GND (ground power supply) pads are used to power the intelligent semiconductor temperature sensor 3 to ensure that its internal temperature measurement unit, storage unit, and microprocessor unit work normally. The remaining 1 to 2 pads (such as the SDA "data line" and SCL "clock line" of the I2C protocol) are used to connect the digital communication interface to realize digital interaction with the DAQ system.

[0025] Furthermore, the aforementioned wired connection may have the following problems: rotating parts can cause wire tangling and wear, leading to malfunctions; wiring in remote structures is costly and difficult to maintain; and confined spaces cannot accommodate multiple wires. Therefore, a low-power wireless module (such as BLE5.0, LoRa, or ZigBee) can be installed on the insulating substrate 1 for communication connection between the strain-sensitive grid 2 and the intelligent semiconductor temperature sensor 3, enabling wireless transmission of compensation coefficient readings and real-time strain / temperature data. Simultaneously, to adapt to the low-power wireless module, a self-powered energy module needs to be designed. For example, if the scenario involves vibration (such as wind turbine blades or engines), a "miniature piezoelectric energy harvester" can be integrated into the substrate to convert vibration energy into electrical energy to power the intelligent semiconductor temperature sensor 3 and the wireless module. If the scenario involves sunlight (such as bridges or outdoor equipment), an ultra-thin flexible solar cell (such as a perovskite solar film) can be covered on the excess surface of the substrate to achieve photo-to-electricity conversion. A backup solution is to integrate a miniature button battery (replaceable, with a battery life of 1-3 years) to ensure stable power supply in extreme environments.

[0026] In a specific embodiment of this application, the compensation coefficients are obtained through the following steps: The strain gauge is placed in a Forster chamber and, under no stress, scanned from -40°C to +120°C with an accuracy of 0.1°C. The resistance change of the strain gauge is recorded using a high-precision digital multimeter, and the readings of the temperature sensing unit on the strain gauge are read simultaneously. A compensation function is fitted based on the resistance change value and the temperature sensing unit readings. For example, a computer fits a third-order polynomial ΔR = A*T³ + B*T² + C*T + D based on the data to accurately describe its zero-point drift. The coefficients A, B, C, and D are calculated as compensation coefficients and, along with a unique ID (for easy identification and control of the strain gauge), are written into the non-volatile storage unit of the strain gauge via the I2C bus.

[0027] Furthermore, during long-term use of strain gauges (such as in aircraft engine blade monitoring and long-term bridge health monitoring), the temperature-resistance characteristics will slowly change due to adhesive aging, sensitive grid metal fatigue, and environmental corrosion (such as humidity and salinity). The factory-calibrated "fixed coefficients" will gradually become ineffective, eventually introducing new measurement errors. To solve this problem, an online self-calibration module can be designed inside the intelligent semiconductor temperature sensor 3. The online self-calibration module can periodically output a known small current to the strain sensitive grid 2 (without affecting normal strain measurement), and calculate the real-time resistance-temperature relationship by reverse calculation. A "dynamic coefficient iterative model" is designed - at each set interval (such as 1 month / 3 months, which can be customized by the user), the deviation between the "current resistance-temperature curve" and the "factory calibration curve" is automatically compared, the compensation coefficient is corrected, and the data is updated to the EEPROM.

[0028] In a specific embodiment of this application, a strain gauge is attached to the turbine blade to be tested. An NI data acquisition card is used, with the analog channel acquiring the strain bridge signal and the digital I / O channel connected to the I2C bus. The LabVIEW program first performs an I2C read operation to obtain four compensation coefficients (A, B, C, D) from the EEPROM of the intelligent semiconductor temperature sensor 3. Then, it enters the main loop. At each sampling point, the program synchronously reads the strain signal and the I2C temperature signal and immediately applies the formula ε_real = ε_total - g(A,B,C,D, T_real) for real-time compensation. Here, ε_total comes from the analog resistance / voltage signal of the strain-sensitive grid 2, T_real comes from the real-time, high-precision digital temperature signal of the temperature sensing unit, g(A,B,C,D, T_real) is the compensation function, and ε_real is the compensated analog resistance / voltage signal of the strain-sensitive grid 2. The final data eliminates the unique temperature drift characteristics of the strain gauge itself.

[0029] The above description is only a preferred embodiment of the present invention and is 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 self-adapting temperature-compensated high-precision strain gauge comprising an insulating substrate, characterized in that, The insulating substrate is integrated with a strain sensitive gate and a smart semiconductor temperature sensor, the smart semiconductor temperature sensor is arranged close to the end of the strain sensitive gate, and the smart semiconductor temperature sensor internally comprises a temperature sensing unit and a non-volatile storage unit.

2. The self-adapting temperature-compensated high-precision strain gauge according to claim 1, characterized in that, The insulating substrate is a polyimide substrate, a silicon substrate or a ceramic substrate.

3. The self-adapting temperature-compensated high-precision strain gauge according to claim 1, characterized in that, The strain sensitive gate is a constantan strain sensitive gate prepared on the insulating substrate through a photoetching process.

4. The self-adapting temperature-compensated high-precision strain gage according to claim 1, wherein, The smart semiconductor temperature sensor is integrated on the insulating substrate through a patch process or a flip-chip process.

5. The self-adapting temperature-compensated high-precision strain gage according to claim 1, wherein, The insulating substrate is provided with a plurality of pads for connecting the strain sensitive gate and the smart semiconductor temperature sensor, and the smart semiconductor temperature sensor internally further comprises a digital communication interface.

6. The self-adapting temperature-compensated high-precision strain gage according to claim 1, wherein, The insulating substrate is provided with a low-power wireless module for connecting the strain sensitive gate and the smart semiconductor temperature sensor and an energy self-supply module for providing electric energy.

7. The self-adapting temperature-compensated high-precision strain gage according to claim 1, wherein, The smart semiconductor temperature sensor internally further comprises an online self-calibration module.

8. A method of measuring a self-adapting temperature-compensated high-precision strain gauge according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: S100, using the digital communication interface or the low-power wireless module, reading the pre-stored strain gauge-specific compensation coefficient from the non-volatile storage unit of the smart semiconductor temperature sensor; S200, synchronously collecting the strain signal from the strain sensitive gate and the real-time temperature signal from the smart semiconductor temperature sensor; S300, using the temperature compensation coefficient read in S100 and the real-time temperature signal collected in S200, performing mathematical operation on the collected strain signal to compensate the drift caused by temperature, so as to obtain the real strain value.

9. The method of claim 8, wherein the method further comprises: The compensation coefficient in S100 is calculated and written into the non-volatile storage unit after the actual temperature test and calibration of the strain sensitive gate on each strain gauge before the strain gauge is shipped, and each strain gauge has a unique ID.

10. The method of claim 9, wherein the method is characterized by: The online self-calibration module periodically outputs a known small current to the strain sensitive gate, obtains the relationship between the real-time resistance of the strain gauge and the temperature through reverse calculation, automatically compares the relationship between the resistance of the strain gauge and the temperature calibrated before shipment every interval of the set period, corrects the compensation coefficient according to the comparison deviation and updates it into the non-volatile storage unit.

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