A stress and strain sensor with secondary temperature self-adaptation function and its application

Abstract

The present invention relates to the field of stress and strain measurement technology, and discloses a stress and strain sensor with a secondary temperature adaptive function and its application. The temperature coefficient of the temperature sensitive unit included in the stress and strain sensor is the same as the temperature coefficient of the measured structure. When the measured structure is affected by temperature and deformed, the temperature sensitive unit and the measured structure are consistent in deformation. At this time, the stress and strain data output by the measuring piece are stress and strain analog signals after primary temperature adaptation. The stress and strain sensor also includes a data acquisition chip and a data processing chip. The data acquisition chip has a built-in temperature sensor for collecting stress and strain values ​​corresponding to each working temperature. A correction model is configured in the data processing chip. The data processing chip receives the stress and strain analog signal after primary temperature adaptation, and after correction by the correction model, obtains a stress and strain digital signal after secondary temperature adaptation. The present invention has a simple structure, low cost, and can accurately filter out deformation caused by temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of stress and strain measurement, and in particular to a stress and strain sensor with a secondary temperature self-adaptation function and applications thereof. Background Art

[0002] The structure being measured can deform due to temperature. During long-term measurements of stress and strain, the deformation caused by temperature can be of the same order of magnitude as that caused by force. In practical applications, stress and strain sensors are commonly used to measure deformation. Traditional stress and strain sensors are typically installed by connecting the sensor's measurement ends to the surface of the structure at an appropriate distance using two columns. This creates a framework structure that measures the stress and strain values ​​of the structure. However, with typical stress and strain sensors, any surface deformation generates an output, but it is impossible to distinguish whether the deformation is caused by force or temperature. This type of sensor is not suitable for long-term measurements.

[0003] To compensate for temperature-induced deformation of the structure under test, some sensors are specifically designed to compensate for the effects of surface temperature. Most compensation methods utilize a temperature-compensating metal block with the same temperature coefficient, onto which strain gauges are attached for temperature compensation. The strain gauge used for measuring the signal is called a measuring plate, while the strain gauge used for temperature compensation is called a compensation plate. Theoretically, the temperature effect can be eliminated by subtracting the signal from the compensation plate from the signal on the sensor's measuring plate. Another approach utilizes differential measurement, forming a full-bridge measurement. The positive output serves as the measuring plate, while the negative output serves as both the measuring plate and the compensation plate. The positive output measuring plate outputs a signal regardless of whether the surface deformation of the structure under test is caused by stress or temperature. However, it cannot distinguish between deformation caused by temperature. The negative output measuring plate can only compensate for the temperature effects on the positive output measuring plate when used as a compensation plate. In short, existing methods cannot distinguish between stress-induced and temperature-induced deformation of the structure under test using the measuring plate alone, requiring a compensation plate to compensate for temperature effects. This undoubtedly complicates the measurement process and increases measurement costs.

[0004] Furthermore, in practical applications, the temperature coefficient of the structure being measured has a range. For example, the linear expansion coefficient of A3 steel is 10-13 με / °C. The linear expansion coefficient may vary at different locations on large steel structures. The temperature coefficient of the metal compensation block is unlikely to be perfectly aligned with the temperature coefficient at different locations on the steel structure, leading to temperature compensation errors. If this error exceeds the system's tolerance range, it will affect the measurement results. Furthermore, in practical applications, the installation location of each sensor varies, making it difficult for traditional sensors to automatically measure the temperature coefficient at the current location, which undoubtedly affects the accuracy of temperature measurement.

[0005] Therefore, it is urgent to propose a stress and strain sensor with simple process and temperature adaptive function. Summary of the Invention

[0006] The purpose of the present invention is to provide a stress and strain sensor with a secondary temperature adaptation function and its application. The first temperature adaptation is achieved by designing the internal structure of the sensor, relying on the measuring piece to distinguish whether the deformation is caused by stress or temperature, without the need for a compensation piece or other temperature compensation device; the second temperature adaptation is to design a correction model to correct the stress and strain simulation signal after the first temperature adaptation.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a stress and strain sensor with a secondary temperature adaptive function. In use, the stress and strain sensor is installed on a measured structure. When the measured structure is subjected to force and deformed, the measuring piece included in the stress and strain sensor outputs a stress and strain analog signal.

[0009] The temperature coefficient of the temperature-sensitive unit included in the stress and strain sensor is the same as the temperature coefficient of the structure being measured. The projection of the temperature-sensitive unit on the structure being measured is located between the central axes of the two installation positions of the stress and strain sensor. When the structure being measured is deformed due to temperature changes, the deformation of the temperature-sensitive unit is consistent with the deformation of the structure being measured, and the measuring piece does not output a stress and strain analog signal. That is, the stress and strain data output by the measuring piece is a stress and strain analog signal after a single temperature adaptation.

[0010] The stress and strain sensor also includes a data acquisition chip with a built-in temperature sensor; the temperature sensor collects stress and strain values ​​corresponding to each ambient temperature, that is, a constant combination is formed by multiple ambient temperatures and their corresponding stress and strain values; the data acquisition chip is also used to collect the stress and strain analog signal output by the measuring piece after the primary temperature adaptation, and convert the stress and strain analog signal after the primary temperature adaptation into a stress and strain digital signal after the primary temperature adaptation;

[0011] The stress and strain sensor also includes a data processing chip, which is equipped with a correction model. The correction model is a difference function between the stress and strain digital signal after the first temperature adaptation and the stress and strain error. The stress and strain error is the product of a constant combination and an independent variable temperature function. The data processing chip receives the stress and strain analog signal after the first temperature adaptation, and after correction by the correction model, obtains the stress and strain digital signal after the second temperature adaptation.

[0012] As a possible implementation, the measuring plate includes a first sensitive grid and a second sensitive grid that are symmetrically and spaced apart. When the structure under test does not deform, the length extension direction of the first sensitive grid and the second sensitive grid is perpendicular to the central axis of the structure under test. When the structure under test deforms under force, the first sensitive grid is stretched to output a positive strain, and the second sensitive grid is compressed to output a negative strain.

[0013] The first sensitive gate and the second sensitive gate are connected to form a first half bridge, and the connection point is connected to the first input pin (11) of the data acquisition chip;

[0014] The invention also includes a first resistor and a second resistor connected in series, forming a second half-bridge, the connection point of which is connected to the second input pin (10) of the data acquisition chip; the first sensitive gate and the other end of the first resistor are connected to the positive electrode of the bridge voltage; the second sensitive gate and the other end of the second resistor are connected to the negative electrode of the bridge voltage and are grounded through the ground pin of the data acquisition chip; the first half-bridge and the second half-bridge form a full-bridge circuit, and the data acquisition chip converts the stress and strain analog signal output by the full-bridge after the first temperature adaptation into a stress and strain digital signal after the first temperature adaptation.

[0015] As a possible implementation, the revised model is:

[0016]

[0017] in, is the stress-strain simulation signal after secondary temperature adaptation, is the stress-strain simulation signal after one temperature adaptation, is the stress-strain error, , is a constant combination, is a function of the independent variable temperature.

[0018] As a possible implementation method, the stress and strain sensor also includes:

[0019] The spindle assembly is mounted on the structure to be measured in such a manner that its central axis is perpendicular to the central axis of the structure to be measured;

[0020] The secondary shaft assembly has a height difference greater than 0 with the main shaft assembly and is installed on the structure to be measured along the measured direction, with the central axis of the secondary shaft assembly being perpendicular to the central axis of the structure to be measured;

[0021] The positioning member defines the relatively higher main shaft assembly or secondary shaft assembly as a positioning shaft assembly; the positioning member is installed at the end of the positioning shaft assembly away from the structure to be measured; one side of the positioning member protrudes from the side opposite to the main shaft assembly and the secondary shaft assembly;

[0022] The cantilever is mounted on the side of the positioning member opposite to the secondary shaft assembly, with the central axis of the cantilever perpendicular to the central axis of the structure being measured; measuring pieces are symmetrically mounted on both sides of the end of the cantilever close to the positioning member;

[0023] A pull rod, one end of which is connected to the top end of the countershaft assembly, and the other end of which is connected to the free end of the cantilever; the central axis of the pull rod is parallel to the central axis of the structure under test;

[0024] The main spindle assembly, positioning parts, pull rods and counter spindle assembly constitute a temperature sensitive unit.

[0025] As a possible implementation, the main shaft assembly includes a main shaft base and a coaxially connected main shaft, and the connection is coplanar; the secondary shaft assembly includes a secondary shaft base and a coaxially connected secondary shaft, and the connection is coplanar.

[0026] As a possible implementation method, the secondary shaft is lower than the main shaft; the lower end plane of the positioning member is coplanar with the connection between the upper end plane of the main shaft; the vertical surface of the positioning member opposite to the secondary shaft has a groove, and the bottom surface of the groove is parallel to the central axis of the main shaft; the vertical surface of the upper end of the cantilever opposite to the main shaft is tightly connected to the bottom surface of the groove to prevent the cantilever from twisting.

[0027] As a possible implementation, the main shaft base and the secondary shaft base are of the same height, and their bottom planes are coplanar with the secondary shaft base, and their top planes are coplanar with each other.

[0028] As a possible implementation, the stress and strain sensor further includes a communication interface chip connected to the data processing chip, and exchanges data with the terminal device via the communication interface chip.

[0029] In a second aspect, the present invention provides an application of a stress and strain sensor with a secondary temperature adaptive function. The stress and strain sensor is installed on a measured structure, large equipment or a large bridge to monitor the deformation caused by stress.

[0030] In a third aspect, the present invention further provides an application method of a stress and strain sensor with a secondary temperature adaptive function, wherein the stress and strain sensor is the stress and strain sensor provided in the first aspect; the application method comprises the following steps:

[0031] S10. Installing the stress and strain sensor on the surface of the structure to be measured along the measurement direction;

[0032] S11. A temperature change cycle is preset, and a constant combination is obtained using the temperature sensor built into the data acquisition chip. This constant combination is then written into the data processing chip to complete the configuration of the correction model.

[0033] S12. When the structure under test is deformed by stress, the pull rod causes the bottom end of the cantilever to displace, further stretching the first sensitive grid and compressing the second sensitive grid. The data acquisition chip then obtains the stress-strain analog signals output by the first and second sensitive grids. Simultaneously with the stress-induced deformation of the structure under test, it is also affected by the ambient temperature. However, the deformation caused by temperature changes is consistent with the deformation of the temperature-sensitive unit, preventing deformation of the first and second sensitive grids. In other words, the deformation caused by temperature changes is not output by the first and second sensitive grids.

[0034] S13. The data acquisition chip receives the stress and strain analog signal after a temperature adaptation and converts it into a stress and strain digital signal after a temperature adaptation;

[0035] S14. The data processing chip receives the stress-strain digital signal after the primary temperature adaptation, and obtains the stress-strain digital signal after the secondary temperature adaptation after correction by the correction model.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The stress and strain sensor provided by the present invention has a two-stage temperature adaptation function. The first temperature adaptation is achieved through the internal structure of the stress and strain sensor, and the second temperature adaptation is achieved through a correction model configured in the data processing chip included in the stress and strain sensor. When measuring the deformation of the measured structure, the two temperature adaptations can accurately filter out the deformation caused by temperature, thereby obtaining more accurate measurement results of the deformation caused by force.

[0038] 2. The stress-strain sensor provided by the present invention collects the degree of influence of temperature on stress and strain at different locations of the measured structure to form a constant combination. The stress-strain error is determined based on the constant combination and the independent variable temperature function. The difference function between the stress-strain digital signal after a single temperature adaptation and the stress-strain error is used as a correction model. The calculation accuracy is high and the deformation caused by temperature can be accurately distinguished from the deformation caused by force.

[0039] 3. The stress and strain sensor provided by the present invention can distinguish deformation caused by temperature from deformation affected by force by relying solely on a measuring plate, without requiring a compensation plate or other temperature compensation device, thus having the advantages of simple process and low cost.

[0040] 4. The stress and strain sensor provided by the present invention is widely applicable to long-term monitoring of large equipment or large bridges. It can eliminate the influence of temperature on deformation and obtain accurate deformation caused by force. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 This is a schematic diagram of a stress and strain sensor installed on a measured structure in an embodiment of the present invention;

[0043] Figure 2 Schematic diagram of the structure of the stress and strain sensor in an embodiment of the present invention;

[0044] Figure 3 This is a circuit diagram of digital signal transmission between the data acquisition chip, data processing chip and communication interface chip in an embodiment of the present invention.

[0045] Reference numerals

[0046] 1-stress and strain sensor, 10-measuring piece, 100-first sensitive grid, 101-second sensitive grid, 11-main shaft assembly, 110-main shaft base, 111-main shaft, 12-secondary shaft assembly, 120-secondary shaft base, 121-secondary shaft, 13-positioning piece, 14-cantilever, 15-pull rod, 16-data acquisition chip, 17-data processing chip, 18-communication interface chip, 2-measured structure. DETAILED DESCRIPTION

[0047] To facilitate a clear description of the technical solutions of the embodiments of the present invention, the words "first" and "second" are used in the embodiments of the present invention to distinguish between identical or similar items with substantially the same functions and effects. For example, the first threshold and the second threshold are merely used to distinguish between different thresholds and do not limit their order. Those skilled in the art will understand that the words "first" and "second" do not limit the quantity or execution order, and the words "first" and "second" do not necessarily mean different.

[0048] It should be noted that, in the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present invention should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0049] In the present invention, "at least one" means one or more, and "more" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. The following at least one item (item) or similar expressions refers to any combination of these items, including any combination of single items (items) or plural items (items). For example, at least one item (item) of a, b or c can mean: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b, c can be single or plural.

[0050] Embodiments of the present invention provide a stress and strain sensor with secondary temperature adaptation and its application. The first temperature adaptation is achieved through the internal structure of the stress and strain sensor, and the second temperature adaptation is achieved through a correction model configured in the data processing chip included in the stress and strain sensor. The present invention is further described below with reference to the accompanying drawings.

[0051] In the first aspect, the embodiment of the present invention provides a stress and strain sensor with a secondary temperature adaptive function, see Figure 1 In use, the stress and strain sensor 1 is installed on the measured structure 2; when the measured structure 2 is deformed by force, the measuring piece 10 included in the stress and strain sensor 1 outputs a stress and strain analog signal;

[0052] See also Figure 2 As a possible implementation, the measuring plate 10 includes a first sensitive grid 100 and a second sensitive grid 101 that are symmetrically and spaced apart. When the structure 2 under test is not deformed, the length extension direction of the first sensitive grid 100 and the second sensitive grid 101 is perpendicular to the central axis of the structure 2 under test. When the structure 2 under test is deformed by force, the first sensitive grid 100 is stretched to output a positive strain, and the second sensitive grid 101 is compressed to output a negative strain. Alternatively, the first sensitive grid 100 is compressed to output a negative strain, and the second sensitive grid 101 is stretched to output a positive strain.

[0053] See also Figure 2 As a possible implementation, the stress-strain sensor 1 further includes:

[0054] The spindle assembly 11 is mounted on the structure 2 to be measured in such a way that its central axis is perpendicular to the central axis of the structure 2 to be measured;

[0055] The secondary shaft assembly 12 has a height difference greater than 0 with the main shaft assembly 11 and is installed on the measured structure 2 along the measured direction. The central axis of the secondary shaft assembly 12 is perpendicular to the central axis of the measured structure 2.

[0056] The positioning member 13 defines the relatively higher main shaft assembly 11 or the secondary shaft assembly 12 as a positioning shaft assembly; the positioning member 13 is installed at the end of the positioning shaft assembly away from the measured structure 2; one side of the positioning member 13 protrudes from the side opposite to the main shaft assembly 11 and the secondary shaft assembly 12;

[0057] The cantilever 14 is installed on the side opposite to the positioning member 13 and the secondary shaft assembly 12, and the central axis of the cantilever 14 is perpendicular to the central axis of the structure 2 to be measured; the measuring pieces 10 are symmetrically installed on both sides of the end of the cantilever 14 close to the positioning member 13; illustratively, the measuring pieces 10 are adhered to both sides of the cantilever 14 using high-temperature curing glue.

[0058] The pull rod 15 has one end connected to the top of the secondary shaft assembly 12, and the other end connected to the suspended end of the cantilever 14; the central axis of the pull rod 15 is parallel to the central axis of the structure under test 2; illustratively, the pull rod 15 is connected to the secondary shaft assembly 12 by threads, and the pull rod 15 and the cantilever 14 can be processed as one piece, or can be connected by screws.

[0059] The main shaft assembly 11 , the positioning member 13 , the pull rod 15 and the secondary shaft assembly 12 constitute a temperature sensitive unit.

[0060] See also Figure 2 As a possible implementation, the main shaft assembly 11 includes a main shaft base 110 and a coaxially connected main shaft 111. The connection is coplanar, ensuring that the bottom plane of the main shaft base 110 is perpendicular to the central axis of the main shaft 111. The countershaft assembly 12 includes a countershaft base 120 and a coaxially connected countershaft 121. The connection is coplanar, ensuring that the bottom plane of the countershaft base 120 is perpendicular to the central axis of the countershaft 121. For example, the main shaft base 110 and the main shaft 111, as well as the countershaft base 120 and the countershaft 121, are both connected by threads.

[0061] See also Figure 2 As a possible implementation, the secondary shaft 121 is lower than the primary shaft 111; the lower end plane of the positioning member 13 is coplanar with the upper end plane of the primary shaft 111 at the junction; the vertical surface of the positioning member 13 opposite the secondary shaft 121 has a groove, the bottom surface of the groove is parallel to the central axis of the primary shaft 111; the vertical surface of the upper end of the cantilever 14 opposite the primary shaft 111 is tightly connected to the bottom surface of the groove to prevent the cantilever 14 from twisting. For example, the lower end plane of the positioning member 13 is threadedly connected to the upper end plane of the primary shaft 111, and the vertical surface of the upper end of the cantilever 14 opposite the primary shaft 111 is screwed to the bottom surface of the groove.

[0062] See also Figure 2As a possible implementation method, the main shaft base 110 and the secondary shaft base 120 are of the same height, and the bottom planes of the main shaft base 110 and the secondary shaft base 120 are coplanar, and the top planes of the main shaft base 110 and the secondary shaft base 120 are coplanar; illustratively, the pull rod 15 and the secondary shaft assembly 12 are connected by threads, and the bottom planes of the main shaft base 110 and the secondary shaft base 120 can be made coplanar by adjusting the screw-in distance.

[0063] See also Figure 2 As an example, after the various parts included in the stress and strain sensor are connected, they are reinforced with anti-loosening glue to ensure the firmness and stability of the stress and strain sensor. In this embodiment, the connection method between the main shaft base 110, the secondary shaft base 120 and the measured structure 2 is not specifically limited, and welding, gluing, permanent magnetic attraction, etc. can be used. During installation and transportation, in order to prevent the relative movement between the main shaft base 110 and the secondary shaft base 120, a special clamp can be used to fix the two, and the clamp can be removed after the installation and transportation is completed; in order to increase the protection level, a shell can also be installed on the main shaft base 110 and the secondary shaft base 120 for protection, as long as it does not affect the relative displacement between the two.

[0064] See also Figure 2 As an example, the main shaft 111, the main shaft base 110, the positioning member 13, the cantilever 14, the pull rod 15, the secondary shaft base 120 and the secondary shaft 121 can be processed by a CNC machine tool, and the dimensions of each part follow the following principle: when the stress and strain sensor is subjected to force along the center line connecting the main shaft base 110 and the secondary shaft base 120, the total deformation of the other parts, except the cantilever 14, can be controlled within the allowable measurement error range compared with the deformation of the cantilever 14.

[0065] The temperature coefficient of the temperature sensitive unit included in the stress and strain sensor is the same as the temperature coefficient of the structure being measured. The projection of the temperature sensitive unit on the structure being measured is located between the central axes of the two installation positions of the stress and strain sensor. When the structure being measured is deformed due to temperature changes, the deformation of the temperature sensitive unit is consistent with the deformation of the structure being measured, and the measuring piece does not output a stress and strain analog signal, that is, the stress and strain analog signal output by the measuring piece is a stress and strain analog signal after one temperature adaptation.

[0066] The stress and strain sensor also includes a data acquisition chip 16, which has a built-in temperature sensor. Exemplarily, the data acquisition chip is soldered to a circuit board, which is mounted within the stress and strain sensor housing. The temperature sensor collects stress and strain values ​​corresponding to each ambient temperature, i.e., a constant combination consisting of multiple ambient temperatures and their corresponding stress and strain values. It should be noted that since there is no heat source within the structure being measured, the temperature of the structure being measured and the surrounding environment are the same. The temperature sensor collecting the ambient temperature is equivalent to collecting the temperature of the structure being measured. The data acquisition chip 16 is also used to collect the stress and strain analog signal output by the measuring piece 10 after a primary temperature adaptation, and to convert the primary temperature adaptation analog signal into a primary temperature adaptation digital signal.

[0067] The following combination Figure 2 The principle of achieving the first temperature adaptation of the present invention is specifically described. The main shaft base 110 and the secondary shaft base 120 of the stress and strain sensor of this embodiment are respectively fixed to two points on the surface of the measured structure 2 extending along the measured direction. When the measured structure 2 is deformed due to force, a relative displacement occurs between the main shaft 111 and the secondary shaft 121. At this time, the secondary shaft 121 drives the pull rod 15, and the pull rod 15 drives the lower end of the cantilever 14 to move, causing the cantilever 14 to bend. One of the first sensitive grid 100 and the second sensitive grid 101 is stretched, outputting a positive strain, while the other is compressed, outputting a negative strain. The difference between the positive and negative strains is twice the strain of the measured structure 2 due to the force. The strain caused by the force can be measured by the data acquisition chip 16. When the measured structure 2 is deformed due to temperature, the temperature coefficient of the temperature sensitive unit is the same as that of the measured structure 2, that is, under the same environment, the two have the same expansion or contraction tendency. Therefore, when the measured structure 2 deforms due to temperature, the temperature-sensitive unit and the measured structure 2 experience the same displacement change. That is, their relative positions do not change. Therefore, the first sensitive grid 100 and the second sensitive grid 101 do not deform and do not output a strain value. The present invention can distinguish between deformation caused by temperature and deformation caused by force using only the temperature-sensitive unit and the measuring plate, without requiring a compensation plate or other temperature compensation device, thus offering the advantages of simple processing and low cost.

[0068] See also Figures 2 to 3As a possible implementation, the first sensitive gate 100 and the second sensitive gate 101 are connected to form a first half-bridge, and the connection point is connected to the first input pin (11) of the data acquisition chip 16; the first resistor R6 and the second resistor R7 are connected in series to form a second half-bridge, and the connection point is connected to the second input pin (10) of the data acquisition chip 16; the other end of the first sensitive gate 100 and the first resistor R6 is connected to the positive electrode of the bridge voltage; the other end of the second sensitive gate 101 and the second resistor R7 is connected to the negative electrode of the bridge voltage and is grounded through the ground pin of the data acquisition chip 16; for example, see Figure 3 The positive pole of the bridge voltage is the +3V voltage connected to the pins (15), (20), and (21) of the data acquisition chip 16, and the negative pole of the bridge voltage is the pins (16) and (17) of the data acquisition chip 16. The first half bridge and the second half bridge constitute a full bridge circuit. When the voltage is applied to the full bridge circuit, a differential voltage is obtained on the pins (10) and (11) of the data acquisition chip 16. After calibration, the differential voltage is the stress and strain analog signal after the first temperature adaptation. The data acquisition chip 16 converts the stress and strain analog signal after the first temperature adaptation output by the full bridge circuit into a stress and strain digital signal after the first temperature adaptation.

[0069] See also Figure 3 The stress and strain sensor also includes a data processing chip 17, which is equipped with a correction model. The correction model is a difference function between the stress and strain digital signal after one temperature adaptation and the stress and strain error. The stress and strain error is the product of a constant combination and an independent variable temperature function. Exemplarily, the constant combination includes multiple constants, such as a proportional constant, an integral constant, a differential constant, etc. The constant combination is obtained in the following manner: the stress and strain sensor is installed at different positions of the measured structure, and a temperature cycle of 24 hours is experienced to collect the degree of influence of the temperature at different positions on the stress and strain to form a constant combination.

[0070] The data processing chip 17 receives the stress-strain analog signal after the primary temperature adaptation and, after correction by the correction model, obtains the stress-strain digital signal after the secondary temperature adaptation. For example, the data acquisition chip 16 writes the constant combination into the data processing chip 17 for permanent storage to complete the configuration of the correction model.

[0071] As a possible implementation, the revised model is:

[0072]

[0073] in, is the stress-strain simulation signal after secondary temperature adaptation, is the stress-strain simulation signal after one temperature adaptation, is the stress-strain error, , is a constant combination, is a function of the independent variable temperature, For temperature.

[0074] The stress and strain sensor provided in this embodiment collects the degree of influence of temperature on stress and strain at different positions of the measured structure to form a constant combination, determines the stress and strain error based on the constant combination and the independent variable temperature function, and uses the difference function between the stress and strain digital signal after one temperature adaptation and the stress and strain error as a correction model. The calculation accuracy is high and the deformation variable caused by temperature can be accurately distinguished from the deformation variable caused by force.

[0075] See also Figure 3 As a possible implementation, the stress and strain sensor further includes a communication interface chip 18 connected to the data processing chip 17 , and exchanges data with the terminal device through the communication interface chip 18 .

[0076] The following combination Figure 3 The principle of realizing the second temperature adaptation of the present invention is specifically described. The data acquisition chip 16 converts the stress and strain analog signal after the first temperature adaptation output by the full-bridge circuit into a stress and strain digital signal after the first temperature adaptation. The output pin (3), output pin (23), and output pin (24) of the data acquisition chip 16 are respectively connected to the input pin (3), input pin (31), and input pin (5) of the data processing chip 17 to send the stress and strain analog signal after the first temperature adaptation to the data processing chip 17. The correction model in the data processing chip 17 corrects the stress and strain analog signal after the first temperature adaptation to obtain the stress and strain digital signal after the second temperature adaptation. The output pin (21), output pin (22), and output pin (25) of the data processing chip 17 are respectively connected to the input pin (4), input pin (1), input pin (2), and (3) of the communication interface chip 18 to realize data exchange with the terminal device through the communication interface chip 18, that is, to realize filtering out the deformation caused by temperature and only outputting the deformation caused by force.

[0077] In a second aspect, the present invention provides an application of a stress and strain sensor with a secondary temperature adaptive function. The stress and strain sensor is installed on a measured structure, large equipment or a large bridge to monitor the deformation caused by stress.

[0078] In a third aspect, the present invention provides an application method of a stress and strain sensor with a secondary temperature adaptive function, wherein the stress and strain sensor is the stress and strain sensor provided in the first aspect; the application method comprises the following steps:

[0079] S10. Mount the stress and strain sensor on the surface of the structure being measured along the measurement direction. For example, the data acquisition chip and data processing chip included in the stress and strain sensor are soldered to a circuit board. The circuit board and other structural components of the stress and strain sensor are installed in a housing. The measuring piece is connected to the corresponding position on the circuit board via wires. After assembly and debugging of the circuit, a complete stress and strain sensor is formed. During use, the main shaft base and secondary shaft base of the stress and strain sensor are bonded to the surface of the structure being measured to measure stress and strain.

[0080] S11. A temperature change cycle is preset, and a constant combination is obtained using the temperature sensor built into the data acquisition chip. This constant combination is then written into the data processing chip to complete the configuration of the correction model.

[0081] S12. When the structure under test is deformed by stress, the pull rod causes the bottom end of the cantilever to displace, further stretching the first sensitive grid and compressing the second sensitive grid. The data acquisition chip then obtains the stress-strain analog signals output by the first and second sensitive grids. Simultaneously with the stress-induced deformation of the structure under test, it is also affected by the ambient temperature. However, the deformation caused by temperature changes is consistent with the deformation of the temperature-sensitive unit, preventing deformation of the first and second sensitive grids. In other words, the deformation caused by temperature changes is not output by the first and second sensitive grids.

[0082] S13. The data acquisition chip receives the stress and strain analog signal after a temperature adaptation and converts it into a stress and strain digital signal after a temperature adaptation;

[0083] S14. The data processing chip receives the stress-strain digital signal after the primary temperature adaptation, and obtains the stress-strain digital signal after the secondary temperature adaptation after correction by the correction model.

[0084] The present invention uses the secondary temperature adaptation function of the stress and strain sensor to accurately filter out the deformation caused by temperature when measuring the deformation of the measured structure through two temperature adaptations, thereby obtaining a more accurate measurement result of the deformation caused by the force.

[0085] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement other variations of the disclosed embodiments by reviewing the drawings, the disclosure, and the drawings, etc. In the specification, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple situations. A single processor or other unit can implement several functions listed in the specification. Certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0086] Although the present invention has been described with reference to specific features and embodiments thereof, it will be apparent that various modifications and combinations thereof may be made without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely illustrative of the present invention and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of the invention. It will be apparent that various modifications and variations of the present invention may be made by those skilled in the art without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such modifications and variations as fall within the scope of the invention and its equivalents.

Claims

1. A stress and strain sensor with secondary temperature adaptive function, characterized in that: The stress and strain sensor comprises: The spindle assembly is mounted on the structure to be measured in such a manner that its central axis is perpendicular to the central axis of the structure to be measured; A secondary shaft assembly, having a height difference greater than 0 with the main shaft assembly, is mounted on the structure to be measured along the measured direction, and the central axis of the secondary shaft assembly is perpendicular to the central axis of the structure to be measured; A positioning member defines a relatively high main shaft assembly or secondary shaft assembly as a positioning shaft assembly; the positioning member is installed at an end of the positioning shaft assembly away from the structure to be measured; one side of the positioning member protrudes from the side of the main shaft assembly opposite to the secondary shaft assembly; a cantilever, the cantilever being mounted on a side of the positioning member opposite to the secondary shaft assembly, the central axis of the cantilever being perpendicular to the central axis of the structure being measured; and measuring pieces being symmetrically mounted on both sides of one end of the cantilever close to the positioning member; a pull rod, one end of which is connected to the top end of the countershaft assembly, and the other end of which is connected to the free end of the cantilever; a central axis of the pull rod is parallel to the central axis of the structure under test; The main shaft assembly, positioning member, pull rod and secondary shaft assembly constitute a temperature sensitive unit; In use, the stress and strain sensor is installed on the structure to be measured; when the structure to be measured is deformed by force, the measuring piece included in the stress and strain sensor outputs a stress and strain analog signal; The temperature coefficient of the temperature-sensitive unit included in the stress and strain sensor is the same as the temperature coefficient of the structure under test. The projection of the temperature-sensitive unit on the structure under test is located between the central axes of the two installation positions of the stress and strain sensor. When the structure under test is deformed due to temperature changes, the deformation of the temperature-sensitive unit is consistent with the deformation of the structure under test, and the measuring piece does not output a stress and strain simulation signal. That is, the stress and strain simulation signal output by the measuring piece is a stress and strain simulation signal after a single temperature adaptation. The stress and strain sensor further includes a data acquisition chip having a built-in temperature sensor; the temperature sensor acquires stress and strain values ​​corresponding to each ambient temperature, i.e., a constant combination is formed by multiple ambient temperatures and their corresponding stress and strain values; the data acquisition chip is further configured to acquire a stress and strain analog signal output by the measuring piece after primary temperature adaptation, and convert the primary temperature adaptation stress and strain analog signal into a primary temperature adaptation stress and strain digital signal; The stress and strain sensor also includes a data processing chip, which is equipped with a correction model. The correction model is a difference function between the stress and strain digital signal after the first temperature adaptation and the stress and strain error, and the stress and strain error is the product of a constant combination and an independent variable temperature function. The data processing chip receives the stress and strain analog signal after the first temperature adaptation, and after correction by the correction model, obtains the stress and strain digital signal after the second temperature adaptation.

2. The stress and strain sensor with secondary temperature self-adaptation function according to claim 1, characterized in that: The measuring piece includes a first sensitive grid and a second sensitive grid that are symmetrically and spaced apart; when the structure to be measured does not deform, the length extension direction of the first sensitive grid and the second sensitive grid is perpendicular to the central axis of the structure to be measured; When the structure under test is deformed by force, the first sensitive grid is stretched to output a positive strain, and the second sensitive grid is compressed to output a negative strain; The first sensitive gate and the second sensitive gate are connected to form a first half bridge, and the connection point is connected to the first input pin of the data acquisition chip; It also includes a first resistor and a second resistor connected in series to form a second half-bridge, and the connection point is connected to the second input pin of the data acquisition chip; the other end of the first sensitive gate and the first resistor is connected to the positive electrode of the bridge supply voltage; the other end of the second sensitive gate and the second resistor is connected to the negative electrode of the bridge supply voltage and is grounded through the ground pin of the data acquisition chip; the first half-bridge and the second half-bridge constitute a full-bridge circuit, and the data acquisition chip converts the stress and strain analog signal output by the full-bridge after the first temperature adaptation into a stress and strain digital signal after the first temperature adaptation.

3. The stress and strain sensor with secondary temperature self-adaptation function according to claim 2, characterized in that: The modified model is: in, is the stress and strain digital signal after secondary temperature adaptation, is the stress and strain digital signal after one temperature adaptation, is the stress-strain error, , is a constant combination, is a function of the independent variable temperature, For temperature.

4. The stress and strain sensor with secondary temperature self-adaptation function according to claim 1, characterized in that: The main shaft assembly includes a main shaft base and a coaxially connected main shaft, and the connection is coplanar; the secondary shaft assembly includes a secondary shaft base and a coaxially connected secondary shaft, and the connection is coplanar.

5. The stress and strain sensor with secondary temperature self-adaptation function according to claim 4, characterized in that: The secondary shaft is lower than the primary shaft; the lower end plane of the positioning member is coplanar with the upper end plane of the primary shaft at the connection; the vertical surface of the positioning member opposite to the secondary shaft has a groove, and the bottom surface of the groove is parallel to the central axis of the primary shaft; the vertical surface of the upper end of the cantilever opposite to the primary shaft is tightly connected to the bottom surface of the groove to prevent the cantilever from twisting.

6. The stress and strain sensor with secondary temperature self-adaptation function according to claim 4, characterized in that: The main shaft base and the secondary shaft base are of the same height, and the bottom planes of the main shaft base and the secondary shaft base are coplanar, and the top planes of the main shaft base and the secondary shaft base are coplanar.

7. The stress and strain sensor with secondary temperature self-adaptation function according to claim 1, characterized in that: The stress and strain sensor further comprises a communication interface chip connected to the data processing chip, and exchanges data with the terminal device via the communication interface chip.

8. An application of a stress and strain sensor with secondary temperature adaptive function, characterized in that: The stress and strain sensor is used to monitor the deformation of the measured structure caused by the stress.

9. An application method of a stress and strain sensor with secondary temperature self-adaptation function, characterized in that: The stress and strain sensor is the stress and strain sensor according to any one of claims 2 to 3; and the application method comprises the following steps: S10. Installing the stress and strain sensor on the surface of the structure to be measured along the measurement direction; S11. A temperature change cycle is preset, and a constant combination is obtained using the temperature sensor built into the data acquisition chip. This constant combination is then written into the data processing chip to complete the configuration of the correction model. S12. When the structure under test is deformed by stress, the pull rod causes the bottom end of the cantilever to displace, further stretching the first sensitive gate and compressing the second sensitive gate. The data acquisition chip obtains the stress and strain analog signals output by the first and second sensitive gates. The measured structure is deformed by stress and the ambient temperature at the same time. The deformation caused by the temperature change is consistent with the deformation of the temperature sensitive unit, so that the first sensitive grid and the second sensitive grid do not deform. That is, the deformation caused by the temperature change is not output through the first sensitive grid and the second sensitive grid. S13. The data acquisition chip receives the stress and strain analog signal after a temperature adaptation and converts it into a stress and strain digital signal after a temperature adaptation; S14. The data processing chip receives the stress-strain digital signal after the primary temperature adaptation, and obtains the stress-strain digital signal after the secondary temperature adaptation after correction by the correction model.

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