High-precision displacement measurement system based on LVDT

Abstract

The invention provides a high-precision displacement measurement system based on an LVDT, and relates to the technical field of displacement measurement, and the system comprises a signal generator, an LVDT displacement sensor, an amplifier, a multiplication mixer, a low-pass filter, and a microcontroller. The signal generator is electrically connected with the LVDT displacement sensor and is used for generating a sine excitation signal and inputting the sine excitation signal into a primary coil of the LVDT displacement sensor to generate a measurement signal; the LVDT displacement sensor is electrically connected with the amplifier, and the amplifier is used for carrying out differential amplification on the measurement signal to obtain a differential amplification signal; the amplifier is electrically connected with the multiplication mixer, and the multiplication mixer is used for multiplying the differential amplification signal by a reference signal to obtain a frequency mixing signal; the multiplication mixer is electrically connected with a low-pass filter, and the low-pass filter is used for filtering the frequency mixing signal to obtain a direct current signal; the low-pass filter is electrically connected with the microcontroller, and the microcontroller is used for converting the direct-current signal into a digital displacement signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of displacement measurement, and particularly relates to a high-precision displacement measurement system based on an LVDT. BACKGROUND

[0002] With the rise of a new round of global technological revolution and industrial reform, Industry 4.0 has become the core driving force for the development of manufacturing industry. Intelligentization, networking and digitization have become the main features of the development of the industrial field. In response to this trend, it aims to promote the upgrading of industrial structure and the improvement of core competitiveness. Under this macro background, precision measurement technology, as a key support for high-end manufacturing, is increasingly becoming an important foundation for ensuring the manufacturing of precision products and high-quality control. Especially in the field of strict requirements for displacement and geometric tolerance, such as aerospace, numerical control machine tools, structural health monitoring, etc., the accurate measurement and perception of micro-displacement have become a technical bottleneck. The development and innovation of precision measurement technology, especially based on displacement sensors, have become the key to improving manufacturing and detection accuracy and enhancing the intelligent level of industry.

[0003] Linear variable differential transformer (LVDT) as a classic displacement sensor, due to its solid structure, simple working principle, no friction and theoretically can provide infinite resolution, is widely used in industrial field. The working principle of LVDT is based on electromagnetic induction effect, which can accurately perceive the change of displacement, so it is widely used in fields with high requirements for size and shape tolerance control, such as high-end numerical control machine tools, aerospace assembly and on-orbit attitude regulation, large bridge health monitoring, etc. The traditional LVDT sensor system converts the measurement data into usable output through signal conditioning circuit and analog signal processing method, which performs well especially in high-precision demand field.

[0004] However, the traditional LVDT usually adopts discrete components to build signal conditioning circuit, resulting in large overall volume and low integration, which is difficult to meet the needs of modern industry for miniaturization and integration. At the same time, many LVDT displacement sensors only provide analog output or simple digital interface, lack of built-in intelligent functions such as self-diagnosis and self-calibration, making it difficult to integrate into modern Internet of Things (IoT) and industrial internet system, unable to realize remote monitoring and data collaboration, limiting its application in intelligent manufacturing and industrial automation. SUMMARY

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a high-precision displacement measurement system based on LVDT, which can solve the problems of traditional LVDTs, which usually use discrete components to build signal conditioning circuits, resulting in a large overall size, low integration, and difficulty in meeting the miniaturization and integration requirements of modern industry. At the same time, many LVDT displacement sensors only provide analog output or simple digital interfaces, lacking built-in intelligent functions such as self-diagnosis and self-calibration, making it difficult to integrate into modern Internet of Things (IoT) and Industrial Internet systems, and hindering remote monitoring and data collaboration, thus limiting their application in intelligent manufacturing and industrial automation.

[0006] This invention proposes a high-precision displacement measurement system based on LVDT, comprising: a signal generator, an LVDT displacement sensor, an amplifier, a multiplier mixer, a low-pass filter, and a microcontroller;

[0007] The signal generator is electrically connected to the LVDT displacement sensor. The signal generator is used to generate a sinusoidal excitation signal and inputs the sinusoidal excitation signal into the primary coil of the LVDT displacement sensor. The secondary coil of the LVDT displacement sensor responds to the sinusoidal excitation signal input into the primary coil to generate a measurement signal.

[0008] The LVDT displacement sensor is electrically connected to the amplifier, which is used to differentially amplify the measurement signal to obtain a differentially amplified signal.

[0009] The amplifier is electrically connected to the multiplier mixer, which is used to multiply the differential amplified signal with the reference signal to obtain a mixed signal containing a second harmonic signal and a difference frequency signal.

[0010] The multiplier mixer is electrically connected to the low-pass filter, which is used to filter the mixed signal to obtain a DC signal.

[0011] The low-pass filter is electrically connected to the microcontroller, which is used to perform analog-to-digital conversion on the DC signal, converting it into a digital displacement signal.

[0012] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0013] In this embodiment of the invention, an integrated signal chain design is employed, highly integrating modules such as a signal generator, an LVDT displacement sensor, an amplifier, a multiplier mixer, a low-pass filter, and a microcontroller. The signal generator drives the LVDT displacement sensor with a sinusoidal excitation signal to generate a measurement signal, which is then differentially amplified by the amplifier. Subsequently, the multiplier mixer and low-pass filter process the signal, and finally, the microcontroller performs analog-to-digital conversion to achieve digital output. This solution not only optimizes the integration of the signal conditioning circuit and reduces the size issues caused by traditional discrete components, but also, through digital processing and the intelligent functions of the microcontroller, enables the system to possess self-diagnosis, self-calibration, and remote monitoring characteristics. This allows it to seamlessly integrate into modern IoT and Industrial Internet environments, meeting the high requirements of precision, reliability, and intelligence in intelligent manufacturing and industrial automation. Attached Figure Description

[0014] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0015] Figure 1 This is a schematic diagram of a high-precision displacement measurement system based on LVDT provided in an embodiment of the present invention. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions 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, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0017] The high-precision displacement measurement system based on LVDT provided in this invention will be described in detail below with reference to the accompanying drawings, through specific embodiments and application scenarios.

[0018] Reference manual attached Figure 1 The diagram shows a structural schematic of a high-precision displacement measurement system based on LVDT provided by an embodiment of the present invention.

[0019] This invention provides a high-precision displacement measurement system based on LVDT, comprising: a signal generator, an LVDT displacement sensor, an amplifier, a multiplier mixer, a low-pass filter, and a microcontroller.

[0020] The signal generator is electrically connected to the LVDT displacement sensor. The signal generator is used to generate a sinusoidal excitation signal, which is input into the primary coil of the LVDT displacement sensor. The secondary coil of the LVDT displacement sensor responds to the sinusoidal excitation signal input into the primary coil to generate a measurement signal.

[0021] Optionally, the excitation signal uses the AD9833 signal source. The ADS9833 is a low-power, programmable DDS waveform generator whose output waveforms include sine, triangle, and square waves, meeting the needs of various detection, signal excitation, and time-domain reflectometry (TDR) applications. The generator's output frequency and phase can be easily adjusted via software programming without the need for external components.

[0022] The LVDT displacement sensor is electrically connected to the amplifier, which is used to differentially amplify the measurement signal to obtain a differential amplified signal.

[0023] Optionally, the AD620 instrumentation amplifier is selected. With its extremely high common-mode rejection ratio (CMRR), the AD620 can effectively amplify differential-mode signals proportional to displacement, while filtering out common-mode noise and excitation signal leakage. Its low noise, low offset, and low temperature drift characteristics directly ensure the high accuracy and long-term stability of the measurement system. Furthermore, the AD620's high input impedance avoids the loading effect on the LVDT output, ensuring signal integrity and making it the core amplification component for extracting pure displacement signals.

[0024] The amplifier is electrically connected to the multiplier mixer, which is used to multiply the differential amplified signal with the reference signal to obtain a mixed signal containing the second harmonic signal and the difference frequency signal.

[0025] Optionally, the multiplicative mixer is the AD835. The AD835 features wide bandwidth and high linearity, enabling precise mixing (multiplication) of the amplified LVDT signal (RF input) with the in-phase, same-frequency reference excitation signal (LO input) from the AD9833. Its output signal contains a DC / low-frequency component proportional to the LVDT displacement amplitude, while shifting unwanted carrier and high-frequency components to higher frequencies. This is a crucial conversion step from high-frequency AC signals to low-frequency displacement information, providing a foundation for subsequent filtering and digital processing.

[0026] The multiplier mixer is electrically connected to a low-pass filter, which is used to filter the mixed signal to obtain a DC signal.

[0027] Optionally, a UAF42 programmable active filter can be used for precision low-pass filtering. With its integrated precision capacitors and flexible configurability, the UAF42 can accurately filter out second harmonics and other high-frequency interference, extracting a pure DC or slowly varying signal proportional to the displacement amplitude. Its high precision, low noise, and stable filtering characteristics are superior to traditional RC passive filters, ensuring the quality of the final signal fed into the ADC and representing a crucial step in ensuring measurement accuracy by purifying the signal.

[0028] The low-pass filter is electrically connected to the microcontroller, which is used to perform analog-to-digital conversion on the DC signal, converting it into a digital displacement signal.

[0029] Optionally, the STM32F103C8T6 microcontroller is selected. Its built-in 12-bit ADC is sufficient to meet the sampling requirements of the demodulated LVDT signal, and its 72MHz clock frequency and Cortex-M3 core provide ample computing power to perform digital filtering, data calibration, linearization processing, and the core adaptive temperature compensation algorithm. The STM32F103C8T6's rich SPI, DMA, timers, and communication peripherals not only facilitate convenient driving of the AD9833 and efficient acquisition of ADC data, but also enable reliable communication with a host computer or cloud platform.

[0030] In this embodiment of the invention, by carefully selecting high-performance, low-noise, and programmable key components, an LVDT displacement measurement system with high precision, high robustness, strong programmability, and good scalability is constructed. This combination not only improves the accuracy and stability of the measurement but also realizes the integration, digitization, and intelligent processing of system functions, greatly enhancing the system's application value in scientific research, industry, and testing.

[0031] In one possible implementation, the high-precision displacement measurement system based on LVDT also includes a follower.

[0032] The follower is electrically connected to the LVDT displacement sensor and is used to suppress common-mode noise when the LVDT displacement sensor acquires data.

[0033] In this embodiment of the invention, by effectively suppressing common-mode noise, the follower helps extract a cleaner measurement signal. Thus, the LVDT sensor can accurately reflect changes in displacement without being affected by external noise, thereby improving the system's accuracy and stability.

[0034] In one possible implementation, a multi-level collaborative temperature compensation mechanism is used to compensate for the temperature of the measurement signal of the LVDT displacement sensor.

[0035] The multi-level collaborative temperature compensation mechanism specifically includes: hardware preliminary temperature compensation based on Wheatstone bridge and software precise temperature compensation based on least squares polynomial fitting.

[0036] Among them, the preliminary temperature compensation of the Wheatstone bridge hardware is achieved by connecting the coil part of the LVDT displacement sensor to the bridge and monitoring the output voltage of the bridge to compensate for the resistance change caused by temperature in real time, thereby reducing the impact of temperature on measurement accuracy.

[0037] Among them, least squares polynomial fitting is used for precise temperature compensation in software within a high-precision displacement measurement system based on LVDT. By fitting the relationship between temperature and measurement error, a compensation model is constructed. This method can correct temperature-induced errors in real time during operation, thereby ensuring the high accuracy and stability of the system.

[0038] In one possible implementation, the hardware-based preliminary temperature compensation based on the Wheatstone bridge specifically employs:

[0039] The primary and secondary coils of the LVDT displacement sensor are symmetrically divided into two parts with similar resistance values, and then connected to adjacent arms of a Wheatstone bridge.

[0040] Preliminary hardware temperature compensation for the measurement signal is performed using a Wheatstone bridge.

[0041] Specifically, the primary and secondary coils of the LVDT are symmetrically divided into two sections with similar resistance values, and these sections are connected to adjacent arms of the Wheatstone bridge. Simultaneously, high-precision, low-temperature-coefficient fixed resistors are strategically placed in the other two arms of the bridge, and precision thermistors can be introduced as auxiliary adjustment or monitoring methods. By designing the bridge structure to ensure that the symmetrically divided LVDT coil sections are in the same temperature environment, the balance principle of the Wheatstone bridge can be utilized to a certain extent to offset the bridge imbalance caused by changes in coil resistance, thereby reducing the direct impact of temperature on the LVDT output signal.

[0042] In this embodiment of the invention, temperature changes typically cause variations in the coil resistance of the LVDT displacement sensor, which can affect the accuracy of the measurement signal. By dividing the primary and secondary coils into two similar sections and connecting them to adjacent arms of the Wheatstone bridge, the Wheatstone bridge can minimize the impact of temperature-induced resistance changes on the signal, thereby effectively reducing errors caused by temperature fluctuations. Simultaneously, the symmetrically segmented LVDT coil design helps improve the system's anti-interference capability. Since the two symmetrical resistive sections are subject to the same temperature changes and exhibit similar behavior in the bridge, any common deviations caused by temperature changes will cancel each other out, thus avoiding the imbalance problems caused by asymmetrical segmentation and reducing the impact of external environmental changes on the system.

[0043] In one possible implementation, software-based precise temperature compensation based on least squares polynomial fitting specifically employs:

[0044] Data is collected synchronously using a digital temperature sensor and an LVDT displacement sensor.

[0045] Record multiple sets of temperature values ​​and corresponding measurement error data under different temperature conditions.

[0046] Based on the principle of least squares, with temperature as the independent variable x and measurement error as the dependent variable y, the relationship between the two can be expressed by the following nth-degree polynomial:

[0047] y = a0 + a1x + a2x 2 +…+a n x n +ε

[0048] Where y represents the measurement error, x represents the temperature, and a0, a1, ..., a n ε represents the polynomial fitting coefficients, and ε represents the residual term.

[0049] Construct the mean squared error loss function:

[0050]

[0051] Where S represents the objective function, y i This represents the actual error during the i-th measurement. Let x represent the prediction error obtained by polynomial fitting for the i-th measurement, m represent the total number of measurements, and x represent the prediction error obtained by polynomial fitting for the i-th measurement. i Let a represent the temperature at the i-th measurement. k represents the fitting coefficient of the k-th polynomial.

[0052] By taking the partial derivatives of the fitting coefficients of each polynomial and setting them to zero, we obtain the normal equation system.

[0053] The optimal polynomial fitting coefficients are determined by solving the normal equation system using Gaussian elimination.

[0054] A temperature-error compensation model is constructed based on the optimal polynomial fitting coefficients.

[0055] Real-time acquisition of temperature data from temperature sensors.

[0056] The real-time temperature data is substituted into the polynomial fitting model to predict the measurement error compensation value at the current temperature.

[0057] The real-time measurement data is corrected based on the measurement error compensation value at the current temperature.

[0058] In this embodiment of the invention, least squares polynomial fitting can accurately establish the relationship between temperature and measurement error, fitting an optimal temperature compensation model through multiple measurement data. This model can predict the magnitude of the error based on the current temperature and dynamically correct it during real-time measurement, ensuring that the impact of temperature fluctuations on measurement accuracy is minimized. Simultaneously, by establishing a simple temperature-error compensation model, the system can respond quickly and effectively to temperature changes without relying on complex real-time calculations. This reduces the complexity of system operation and improves system stability.

[0059] In one possible implementation, after the microcontroller performs analog-to-digital conversion on the DC signal to convert it into a digital displacement signal, a first-order recursive filtering algorithm or a moving average filtering algorithm is used to filter the digital displacement signal.

[0060] The first-order recursive filtering algorithm (also known as IIR (Infinite Impulse Response) filtering) smooths the signal by performing a weighted average of the input signal and the previous output.

[0061] The moving average filtering algorithm is a linear filtering method that smooths a signal by calculating the average value of the input signal over a time window. Typically, this method uses a fixed-length window, averaging the signal values ​​within that window as the output.

[0062] In one possible implementation, the first-order recursive filtering algorithm specifically includes:

[0063] The current input is combined with the previous filtered output using weighted averages to determine the current filtered output:

[0064] y(n) = ax(n) + (1-a)y(n-1)

[0065] Where y(n) represents the nth filtered output signal, x(n) represents the nth input signal, y(n-1) represents the (n-1)th filtered output signal, and a represents the weighting coefficient of the input signal.

[0066] The cutoff frequency is controlled by adjusting the weighting coefficient 'a' of the input signal.

[0067] If the noise interference is strong, then 0 < a < 0.5, and the high-frequency components are strongly filtered out with a low cutoff frequency to smooth the displacement signal.

[0068] If the displacement signal changes rapidly, then 0.5 < a < 1, which suppresses moderate-intensity clutter while preserving the dynamic details of the signal.

[0069] In this embodiment of the invention, the weighting coefficient 'a' determines the cutoff frequency of the filter. By adjusting 'a', the filter's response can be controlled. If high-frequency noise is to be filtered out, a lower cutoff frequency can be selected; conversely, if higher-frequency signal components are to be retained, a higher cutoff frequency can be selected. This characteristic makes the filter highly flexible, allowing the filtering strategy to be adjusted in different application scenarios.

[0070] In one possible implementation, the moving average filtering algorithm specifically includes:

[0071] The arithmetic mean of N consecutive sampled values ​​is calculated using a sliding window.

[0072] The filtering strength and response speed are controlled by adjusting the sliding window length N.

[0073] If environmental interference is severe, the value of N should be between 10 and 20 to enhance the ability to suppress noise and output a smoother signal.

[0074] If the signal itself changes rapidly and dynamic information needs to be captured in a timely manner, then the value of N is between 3 and 5, which preserves the rapid change characteristics of the signal to a certain extent while reducing the impact of low-frequency noise.

[0075] In this embodiment of the invention, the noise suppression capability and dynamic response speed of the filter can be flexibly controlled by adjusting the length N of the sliding window. When environmental interference is severe, increasing N can better filter out noise and obtain a smooth signal; while when the signal changes rapidly, decreasing N can preserve the dynamic details of the signal and avoid losing important information. This approach provides high flexibility, allowing the filter's performance to be adjusted according to different application requirements, enabling it to both smooth the signal and capture signal changes in a timely manner.

[0076] In this embodiment of the invention, it can be easily integrated into a microcontroller (MCU) to perform real-time filtering on the digital signal after A / D conversion from the sensor. With its simple calculation logic, ease of implementation, and low resource consumption, it can effectively remove noise while taking into account the real-time and accuracy requirements of the data.

[0077] In one possible implementation, the high-precision displacement measurement system based on LVDT also includes a Wi-Fi module.

[0078] The Wi-Fi module is used to securely upload digital displacement signals via the encrypted MQTT protocol.

[0079] In one possible implementation, the LVDT-based high-precision displacement measurement system further includes a visual user interface.

[0080] A visual user interface is used to display digital displacement signals, temperature, and equipment status.

[0081] Specifically, the platform boasts powerful dashboard building capabilities and features a user-friendly data visualization interface. Through flexible configuration of various charts (such as real-time graphs and historical trend charts), instruments (such as digital displays and percentage progress bars), and tables, it intuitively and in real-time displays key information such as micrometer-level displacement data measured by the LVDT system, ambient temperature changes, and equipment operating status.

[0082] In this embodiment of the invention, by designing a visual user interface for the LVDT-based high-precision displacement measurement system, key information such as displacement signals, temperature changes, and equipment status can be displayed intuitively and in real time. This also significantly improves the system's usability, real-time response capability, fault diagnosis efficiency, and data analysis capabilities. Flexible configuration and customization options allow users to tailor the interface to their specific needs, enhancing the system's adaptability and user experience. Furthermore, it provides robust data support for future maintenance, optimization, and decision-making.

[0083] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0084] In this embodiment of the invention, an integrated signal chain design is employed, highly integrating modules such as a signal generator, an LVDT displacement sensor, an amplifier, a multiplier mixer, a low-pass filter, and a microcontroller. The signal generator drives the LVDT displacement sensor with a sinusoidal excitation signal to generate a measurement signal, which is then differentially amplified by the amplifier. Subsequently, the multiplier mixer and low-pass filter process the signal, and finally, the microcontroller performs analog-to-digital conversion to achieve digital output. This solution not only optimizes the integration of the signal conditioning circuit and reduces the size issues caused by traditional discrete components, but also, through digital processing and the intelligent functions of the microcontroller, enables the system to possess self-diagnosis, self-calibration, and remote monitoring characteristics. This allows it to seamlessly integrate into modern IoT and Industrial Internet environments, meeting the high requirements of precision, reliability, and intelligence in intelligent manufacturing and industrial automation.

[0085] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A high-precision displacement measurement system based on LVDT, characterized in that, include: Signal generator, LVDT displacement sensor, amplifier, multiplier mixer, low-pass filter, and microcontroller; The signal generator is electrically connected to the LVDT displacement sensor. The signal generator is used to generate a sinusoidal excitation signal and inputs the sinusoidal excitation signal into the primary coil of the LVDT displacement sensor. The secondary coil of the LVDT displacement sensor responds to the sinusoidal excitation signal input into the primary coil to generate a measurement signal. The LVDT displacement sensor is electrically connected to the amplifier, which is used to differentially amplify the measurement signal to obtain a differentially amplified signal. The amplifier is electrically connected to the multiplier mixer, which is used to multiply the differential amplified signal with the reference signal to obtain a mixed signal containing a second harmonic signal and a difference frequency signal. The multiplier mixer is electrically connected to the low-pass filter, which is used to filter the mixed signal to obtain a DC signal. The low-pass filter is electrically connected to the microcontroller, which is used to perform analog-to-digital conversion on the DC signal, converting it into a digital displacement signal.

2. The high-precision displacement measurement system based on LVDT according to claim 1, characterized in that, Also includes: Follower; The follower is electrically connected to the LVDT displacement sensor, and the follower is used to suppress common-mode noise when the LVDT displacement sensor acquires data.

3. The high-precision displacement measurement system based on LVDT according to claim 1, characterized in that, A multi-level collaborative temperature compensation mechanism is adopted to compensate for the temperature of the measurement signal of the LVDT displacement sensor; The multi-level collaborative temperature compensation mechanism specifically includes: hardware preliminary temperature compensation based on Wheatstone bridge and software precise temperature compensation based on least squares polynomial fitting.

4. The high-precision displacement measurement system based on LVDT according to claim 3, characterized in that, The preliminary temperature compensation based on the Wheatstone bridge specifically adopts the following approach: The primary coil and the secondary coil of the LVDT displacement sensor are symmetrically divided into two parts with similar resistance values, and then connected to the adjacent arms of the Wheatstone bridge respectively. The measurement signal is initially compensated for in hardware using the Wheatstone bridge.

5. The high-precision displacement measurement system based on LVDT according to claim 3, characterized in that, The software-based precise temperature compensation based on least squares polynomial fitting specifically employs: Data is collected synchronously by a digital temperature sensor and the LVDT displacement sensor. Record multiple sets of temperature values ​​and corresponding measurement error data under different temperature conditions; Based on the principle of least squares, with temperature as the independent variable x and measurement error as the dependent variable y, the relationship between the two can be expressed by the following nth-degree polynomial: y=a0+a1x+a2x 2 +…+a n x n +e Where y represents the measurement error, x represents the temperature, and a0, a1, ..., a n ε represents the polynomial fitting coefficients, and ε represents the residual term. Construct the mean squared error loss function: Where S represents the objective function, y i This represents the actual error during the i-th measurement. Let x represent the prediction error obtained by polynomial fitting for the i-th measurement, m represent the total number of measurements, and x represent the prediction error obtained by polynomial fitting for the i-th measurement. i Let a represent the temperature at the i-th measurement. k Represents the fitting coefficients of the k-th polynomial; By taking the partial derivatives of the fitting coefficients of each polynomial and setting them to zero, we obtain the normal equation system. The optimal polynomial fitting coefficients are determined by solving the normal equation system using Gaussian elimination. A temperature-error compensation model is constructed based on the optimal polynomial fitting coefficients. Real-time acquisition of temperature data from the temperature sensor; The real-time temperature data is substituted into the polynomial fitting model to predict the measurement error compensation value at the current temperature. The real-time measurement data is corrected based on the measurement error compensation value at the current temperature.

6. The high-precision displacement measurement system based on LVDT according to claim 1, characterized in that, After the microcontroller performs analog-to-digital conversion on the DC signal to convert it into a digital displacement signal, a first-order recursive filtering algorithm or a moving average filtering algorithm is used to filter the digital displacement signal.

7. The high-precision displacement measurement system based on LVDT according to claim 6, characterized in that, The first-order recursive filtering algorithm specifically includes: The current input is combined with the previous filtered output using weighted averages to determine the current filtered output: y(n) = ax(n) + (1-a)y(n-1) Where y(n) represents the nth filtered output signal, x(n) represents the nth input signal, y(n-1) represents the (n-1)th filtered output signal, and a represents the weighting coefficient of the input signal; The cutoff frequency is controlled by adjusting the weighting coefficient 'a' of the input signal; If the noise interference is strong, then 0 < a < 0.5, and the high-frequency components are strongly filtered out with a low cutoff frequency to smooth the displacement signal. If the displacement signal changes rapidly, then 0.5 < a < 1, which suppresses moderate-intensity clutter while preserving the dynamic details of the signal.

8. The high-precision displacement measurement system based on LVDT according to claim 6, characterized in that, The moving average filtering algorithm specifically includes: Calculate the arithmetic mean of N consecutive sampled values ​​using a sliding window; The filtering strength and response speed are controlled by adjusting the sliding window length N; If environmental interference is severe, the value of N should be between 10 and 20 to enhance the ability to suppress noise and output a smoother signal. If the signal itself changes rapidly and dynamic information needs to be captured in a timely manner, then the value of N is between 3 and 5, which preserves the rapid change characteristics of the signal to a certain extent while reducing the impact of low-frequency noise.

9. The high-precision displacement measurement system based on LVDT according to claim 1, characterized in that, Also includes: Wi-Fi module; The Wi-Fi module is used to securely upload the digital displacement signal via the encrypted MQTT protocol.

10. The high-precision displacement measurement system based on LVDT according to claim 1, characterized in that, Also includes: Visual user interface; The visual user interface is used to display the digital displacement signal, temperature, and equipment status.

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