Wireless acquisition system for torsional stress of elastic shaft

Abstract

The invention discloses an elastic shaft torsional stress wireless acquisition system, which comprises a stress signal acquisition module, a signal processing module, an A / D conversion module, a microprocessor, a wireless transceiver module and a power supply module, and is characterized in that the system is connected with a Wheatstone bridge by using uniformly distributed strain gauge sensors, so that the sensitivity and stability of measurement are improved; meanwhile, the temperature compensation function is achieved. In the signal processing module, through cooperative work of a differential amplification unit, a noise suppression unit and a closed-loop adjustment unit, effective amplification processing is carried out on stress signals, the signal-to-noise ratio of the signals is remarkably improved, and system errors are eliminated. Particularly, due to the design of the noise suppression unit, the influence of environmental factor interference and system thermal noise on torsion stress acquisition signals is effectively suppressed, and high-quality data is provided for subsequent signal processing and analysis. In addition, the system can accurately transmit key data to an upper computer in real time, and remote monitoring and analysis are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical stress measurement, and in particular to a wireless acquisition system for elastic shaft torsional stress. Background Art

[0002] In the field of rotating power machinery, the working state and performance of the elastic shaft, as an important part of the transmission system, directly affect the stability and reliability of the entire mechanical system. When the elastic shaft is subjected to torque, it will produce corresponding mechanical deformation, and there is a direct correlation between this deformation and the torque value. Therefore, by accurately measuring the torsional stress of the elastic shaft, the load state of the mechanical system can be evaluated in real time, potential failures can be predicted, and an important basis for subsequent maintenance and optimization can be provided.

[0003] At present, the main method for collecting torsional stress of elastic shafts is to install strain gauge sensors on the elastic shafts, convert the detected mechanical deformation into electrical signals, and transmit them to the data acquisition and analysis system by wire. For example, the Chinese invention patent with application number 201811432431.X discloses a strain-type torque measurement system and method, in which the torque generated by the rotating shaft is converted into a voltage signal by a bridge circuit composed of resistors R1, R2, R3, and R4, and then the voltage signal is amplified, filtered, and DC-shifted by a signal adjustment circuit, and then converted into a digital signal by a single-chip microcomputer-controlled digital-to-analog conversion circuit (ADC), and finally the digital signal is sent to the host computer for analysis and processing to obtain the torque value. However, in actual operation, the existing resistance strain gauges usually adopt the patch method of two pairs of torque strain gauges. In actual operation, the two strain gauges at 90° to each other will interfere with each other, which reduces the ability of the strain gauge to respond to strain.

[0004] In the signal adjustment circuit, the mechanical vibration generated by the elastic shaft during operation will not only cause wear and fatigue to itself, but may also be transmitted to the acquisition system through the sensor, resulting in problems such as signal waveform distortion and phase shift, which greatly reduces the quality of the collected signal. In addition, environmental interference and system thermal noise are also important factors affecting the quality of stress signal acquisition. This interference may cause signal distortion, loss or erroneous measurement values, which seriously affects the accurate measurement of the torsional stress of the elastic shaft. Furthermore, the wired transmission method limits the layout and movement of the stress acquisition system, and when the signal transmission distance is long, the signal attenuation problem is particularly prominent, affecting the stability and reliability of the system.

[0005] In view of the above situation, the present invention aims to provide a new solution to solve this problem. Summary of the invention

[0006] In view of the above situation, in order to overcome the defects of the prior art, the purpose of the present invention is to provide a wireless acquisition system for elastic shaft torsional stress.

[0007] The technical solution is: a wireless acquisition system for elastic shaft torsional stress, including:

[0008] A stress signal acquisition module, comprising a plurality of strain gauge sensors, each of which is attached to the surface of the elastic shaft to be measured, and is used to detect the mechanical deformation of the elastic shaft, thereby generating an electrical signal proportional to the torque value;

[0009] A signal processing module, used to amplify the electrical signal, improve the signal-to-noise ratio of the signal, and eliminate system errors;

[0010] An A / D conversion module, used for converting the output signal of the signal processing module into a digital quantity;

[0011] A microprocessor, used for receiving the digital signal output by the A / D conversion module, and performing data processing, storage and transmission control;

[0012] A wireless transceiver module is used to transmit the data processed by the microprocessor to the host computer wirelessly; and

[0013] Power module, used for power supply and management of the entire system;

[0014] Wherein, the signal processing module includes:

[0015] A differential amplification unit, used to differentially amplify the output signal of the stress signal acquisition module and add a reference voltage during the amplification process to ensure the stability and accuracy of the signal;

[0016] A noise suppression unit is used to perform secondary amplitude modulation amplification on the output signal of the differential amplification unit, and add high-frequency filtering and thermal noise suppression processing during the amplification process to enhance the signal-to-noise ratio of the stress acquisition signal;

[0017] The closed-loop regulation unit is used to perform closed-loop feedback regulation on the two-stage amplification process to eliminate system errors.

[0018] Preferably, the number of the strain gauge sensors is 4, and they are evenly distributed every 90° on the circumference of the elastic shaft surface.

[0019] Preferably, the strain gauge sensors in the stress signal acquisition module are electrically connected in the form of a Wheatstone bridge, and an RC filter is provided at the signal output end of the Wheatstone bridge.

[0020] Preferably, the differential amplification unit includes an op amp AR1 and an op amp AR2, the non-inverting input terminal and the inverting input terminal of the op amp AR1 are connected to the electrical signal output terminal of the stress signal acquisition module, the non-inverting input terminal of the op amp AR1 is grounded through a resistor R7, the inverting input terminal of the op amp AR1 is connected to the output terminal of the op amp AR1 through a resistor R8, and the inverting input terminal and the output terminal of the op amp AR2 are connected through a resistor R9, the non-inverting input terminal of the op amp AR2 is connected to a reference power supply through a resistor R10, and is grounded through a parallel resistor R11 and a capacitor C3.

[0021] Preferably, the noise suppression unit includes an op amp AR3, a non-inverting input terminal of the op amp AR3 is connected to an output terminal of the op amp AR1 through a resistor R12, an inverting input terminal of the op amp AR3 is connected to a resistor R13, a resistor R14, a capacitor C4 and one end of a capacitor C5, the other end of the resistor R13 is connected to the other end of the capacitor C4 and the output terminal of the op amp AR3 through an adjustable resistor RP1, the other ends of the resistor R14 and the capacitor C5 are connected to a drain of a field effect transistor Q1, the source and the gate of the field effect transistor Q1 are grounded, the output terminal of the op amp AR3 is connected to the A / D conversion module through a resistor R15, and is connected to the non-inverting input terminal of the op amp AR1 through the closed-loop adjustment unit.

[0022] Preferably, the closed-loop regulation unit includes a resistor R16, a resistor R17 and a capacitor C6, one end of the resistor R16 and the capacitor C6 are connected to the output end of the operational amplifier AR3, and the other end of the resistor R16 and the capacitor C6 are connected to the in-phase input end of the operational amplifier AR1 through the resistor R17.

[0023] Preferably, the A / D conversion module uses an ADS1256 analog-to-digital converter.

[0024] Preferably, the microprocessor is a STC8H1K08-TSSOP20 single chip microcomputer.

[0025] Preferably, the wireless transceiver module is an ESP-07S Wi-Fi module.

[0026] Preferably, the power module comprises:

[0027] SX1308 boost converter, which increases the external input voltage to +5V output, is used to provide system +5V power supply;

[0028] The voltage regulator chip is used to reduce the +5V voltage output by the SX1308 boost converter to +3.3V, so as to provide a +3.3V power supply to the system.

[0029] Through the above technical scheme, the beneficial effects of the present invention are as follows: the wireless acquisition system of torsional stress of elastic shaft of the present application, by adopting wireless transmission technology, effectively solves the problems of layout flexibility and signal attenuation of traditional wired methods, and enhances the reliability of the system. The system uses evenly distributed strain gauge sensors and Wheatstone bridge connection to improve the sensitivity and stability of measurement, and has temperature compensation function. In the signal processing module, through the coordinated work of differential amplifier unit, noise suppression unit and closed-loop regulation unit, not only the stress signal is effectively amplified, but also the signal-to-noise ratio of the signal is significantly improved, and the system error is eliminated. In particular, the design of the noise suppression unit effectively suppresses the influence of environmental factors and system thermal noise on the torsional stress acquisition signal, and provides high-quality data for subsequent signal processing and analysis. In addition, the system can transmit key data to the host computer in real time and accurately, realize remote monitoring and analysis, and provide strong technical support for evaluating mechanical load status and predicting faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a module structure block diagram of the wireless acquisition system for elastic shaft torsional stress of the present invention.

[0031] Figure 2 This is a three-dimensional diagram of a strain gauge sensor attached to the surface of an elastic shaft in one embodiment of the present invention.

[0032] Figure 3 It is a planar development diagram of a strain gauge sensor attached to the surface of an elastic shaft in one embodiment of the present invention.

[0033] Figure 4 FIG. 4 is a circuit schematic diagram of a stress signal acquisition module in an embodiment of the present invention.

[0034] Figure 5 FIG. 4 is a circuit schematic diagram of a signal processing module in an embodiment of the present invention.

[0035] Figure 6 FIG. 4 is a wiring diagram of the peripheral circuit of the A / D conversion module in one embodiment of the present invention.

[0036] Figure 7 FIG. 1 is a wiring diagram of a peripheral circuit of a microprocessor in one embodiment of the present invention.

[0037] Figure 8 This is a main program flow chart of A / D acquisition performed by a microprocessor in one embodiment of the present invention.

[0038] Fig. 9 The figure is a flow chart of the configuration procedure of the A / D conversion module by the microprocessor in one embodiment of the present invention.

[0039] Fig.10FIG. 4 is a wiring diagram of a peripheral circuit of a Wi-Fi module in an embodiment of the present invention.

[0040] Fig.11 FIG. 1 is a peripheral circuit wiring diagram of a SX1308 boost converter in one embodiment of the present invention.

[0041] Fig.12 FIG. 1 is a wiring diagram of a peripheral circuit of a voltage stabilizing chip in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The above and other technical contents, features and effects of the present invention are described in detail below with reference to the attached Figure 1 To Attachment Fig.12 The detailed description of the embodiments will clearly show that the structural contents mentioned in the following embodiments are all based on the drawings in the specification.

[0043] Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0044] like Figure 1 As shown, a wireless acquisition system for elastic shaft torsional stress comprises:

[0045] A stress signal acquisition module, including a plurality of strain gauge sensors, each of which is attached to the surface of the elastic shaft to be measured, and is used to detect the mechanical deformation of the elastic shaft, thereby generating an electrical signal proportional to the torque value;

[0046] The signal processing module is used to amplify the electrical signal, improve the signal-to-noise ratio, and eliminate system errors;

[0047] A / D conversion module, used for converting the output signal of the signal processing module into digital quantity;

[0048] A microprocessor (MCU) is used to receive the digital signal output by the A / D conversion module and perform data processing, storage and transmission control;

[0049] A wireless transceiver module is used to transmit the data processed by the microprocessor to the host computer wirelessly; and

[0050] Power module, used for power supply and management of the entire system.

[0051] In a specific embodiment, Figure 2 and 3 As shown in the figure, the stress signal acquisition module uses 4 strain gauge sensors, which are evenly distributed every 90° on the circumference of the elastic shaft surface to eliminate the influence of transverse shear force. At the same time, the 4 strain gauge sensors are electrically connected in the form of a Wheatstone bridge, which can greatly improve the sensitivity and stability of the measurement and have good temperature compensation capabilities. In addition, Figure 4As shown, in order to improve the output accuracy of the collected electrical signal, an RC filter is set at the signal output end of the Wheatstone bridge. By filtering out high-frequency noise, the collected signal is closer to the true value and has good temperature compensation capability.

[0052] When measuring torque, the electrical signals output by the Wheatstone bridge composed of strain gauge sensors are very weak, usually at the millivolt level. At the same time, when the transmission distance is long, the operating environment is relatively harsh and the signal is easily interfered by the outside world. Therefore, this application uses a signal processing module to process the electrical signal output by the stress signal acquisition module, such as Figure 5 As shown, specifically including:

[0053] The differential amplifier unit is used to differentially amplify the output signal of the stress signal acquisition module and add a reference voltage during the amplification process to ensure the stability and accuracy of the signal;

[0054] A noise suppression unit is used to perform secondary amplitude modulation amplification on the output signal of the differential amplification unit, and add high-frequency filtering and thermal noise suppression processing during the amplification process to enhance the signal-to-noise ratio of the stress acquisition signal;

[0055] The closed-loop regulation unit is used to perform closed-loop feedback regulation on the two-stage amplification process to eliminate system errors.

[0056] In a specific embodiment, the differential amplifier unit is an important component of the signal processing module. Its core function is to effectively amplify the weak electrical signal output by the stress signal acquisition module and suppress common mode noise and external interference, thereby improving the amplitude and stability of the signal. Figure 5 As shown, the differential amplifier unit includes an op amp AR1 and an op amp AR2, which work together to achieve accurate processing of the electrical signal. In specific settings, the in-phase input terminal and the inverting input terminal of the op amp AR1 are connected to the electrical signal output terminal of the stress signal acquisition module, the in-phase input terminal of the op amp AR1 is grounded through a resistor R7, the inverting input terminal of the op amp AR1 is connected to the output terminal of the op amp AR1 through a resistor R8, and the inverting input terminal and the output terminal of the op amp AR2 are connected through a resistor R9, the in-phase input terminal of the op amp AR2 is connected to the reference power supply through a resistor R10, and is grounded through a parallel resistor R11 and a capacitor C3.

[0057] Among them, the operational amplifier AR1 uses the differential amplifier principle to perform a first-level amplification processing on the weak electrical signal output by the stress signal acquisition module, effectively suppressing common-mode noise and external interference, and improving the signal's anti-interference ability. At the same time, the operational amplifier AR2 applies a reference voltage to the differential amplifier through the resistor R9. The reference voltage provides a reference point for the differential amplifier, enabling it to amplify according to the difference between the input signal and the reference voltage, thereby more effectively processing the weak electrical signal output by the stress signal acquisition module and improving the amplification accuracy.

[0058] In order to improve the stability of the reference power supply, in the above, resistor R11 and capacitor C3 are used to eliminate ripples in the reference power supply, and then the operational amplifier AR2 is used to perform stabilization processing using the voltage follower principle, ensuring that the inverting input terminal of the operational amplifier AR1 can obtain a stable reference voltage.

[0059] In order to further suppress the influence of environmental factors and system thermal noise on the torsional stress acquisition signal, the signal output by the noise suppression unit receiving differential amplifier is further amplified and filtered. Figure 5 As shown, specifically, the noise suppression unit includes an op amp AR3, the in-phase input terminal of the op amp AR3 is connected to the output terminal of the op amp AR1 through a resistor R12, the in-phase input terminal of the op amp AR3 is connected to a resistor R13, a resistor R14, a capacitor C4 and one end of a capacitor C5, the other end of the resistor R13 is connected to the other end of the capacitor C4 and the output terminal of the op amp AR3 through an adjustable resistor RP1, the other ends of the resistor R14 and the capacitor C5 are connected to the drain of the field effect transistor Q1, the source and the gate of the field effect transistor Q1 are grounded, the output terminal of the op amp AR3 is connected to the A / D conversion module through a resistor R15, and is connected to the in-phase input terminal of the op amp AR1 through a closed-loop adjustment unit.

[0060] When the signal passes through the noise suppression unit, the op amp AR3 will perform secondary amplitude modulation amplification on it, that is, by changing the resistance value of the adjustable resistor RP1 to adjust the amplification gain of the op amp AR3, so as to achieve precise control of the signal amplification degree. At the same time, during the secondary amplification process, the capacitor C4 performs phase compensation on the amplified signal of the op amp AR3, thereby reducing the distortion and phase shift during the signal acquisition process; the capacitor C5 effectively filters and suppresses the thermal noise generated by the resistor R14 at the inverting input end of the op amp AR3, further improving the purity and clarity of the signal; in addition, the field effect tube Q1 is used here as a noise filter, and its working principle is to use the capacitance effect between its gate and source to absorb and suppress high-frequency noise. In this way, the signal-to-noise ratio of the signal processed by the noise suppression unit is significantly improved, providing more accurate and reliable data for subsequent signal processing and analysis.

[0061] In order to eliminate the system error generated in the process of torsional stress acquisition and amplification, a closed-loop regulation unit is used to perform closed-loop feedback regulation on the two-stage amplification process. Figure 5 As shown, specifically, the closed-loop regulation unit includes a resistor R16, a resistor R17 and a capacitor C6, one end of the resistor R16 and the capacitor C6 are connected to the output end of the operational amplifier AR3, and the other end of the resistor R16 and the capacitor C6 are connected to the non-inverting input end of the operational amplifier AR1 through the resistor R17.

[0062] In the specific feedback regulation process, the RC components in the closed-loop regulation unit buffer and filter the output signal of the op amp AR3, which helps to stabilize the closed-loop response of the system. The feedback signal is sent to the non-inverting input of the op amp AR1, which compares the feedback signal with the original input signal, generates a deviation signal, and adjusts the output through its internal circuit to eliminate system errors. This process is continuous and dynamically adjusted as the input signal changes, which helps to suppress the impact of external interference and internal noise on the system and enhance the stability of the system.

[0063] The amplification and conditioning of the torsional stress electrical signal by the above-mentioned signal processing module not only improves the anti-interference ability and measurement accuracy of the signal, but also provides high-quality torsional stress data for subsequent signal processing and analysis, thereby ensuring the reliability and stability of the entire elastic shaft torsional stress wireless acquisition system.

[0064] The electrical signal processed by the signal processing module is sent to the A / D conversion module for digital quantity conversion. Figure 6 As shown in the figure, the ADS1256 analog-to-digital converter is selected as the main chip of the A / D digital-to-analog conversion module. The ADS1256 is a high-precision, 24-bit analog-to-digital converter with high-speed data acquisition capabilities and low noise characteristics. The chip has a built-in programmable gain amplifier (PGA) that can amplify the signal to 1, 2, 4, 8, 16, 32 or 64 times according to actual application needs. At the same time, the ADS1256 also provides an SPI digital interface to facilitate data transmission with the microcontroller.

[0065] like Figure 7 As shown in the figure, the microprocessor uses the STC8H1K08-TSSOP20 single-chip microcomputer developed by STC. This single-chip microcomputer not only has the characteristics of high performance, high reliability, and convenient development environment, but also integrates a rich peripheral interface and powerful functional units. Its built-in high-performance CPU can efficiently handle various complex tasks, and at the same time provides a rich peripheral interface, such as UART, SPI, I2C, etc., which is convenient for connection and data transmission with other modules, providing a strong guarantee for the stable operation of the system.

[0066] After the system is powered on, the microprocessor first initializes the corresponding port and configures the ADS1256 through SPI, mainly including reset, data rate, input buffer and other settings and system self-calibration. The ADS1256 must work in the slave mode of SPI communication, and the chip select signal CS must always remain at a low level during communication. The microprocessor sends a command word to the ADS1256 on the falling edge of the clock signal SCLK, reads the ADS1256 data on the rising edge of SCLK, and determines whether the A / D conversion is completed by querying the level of the corresponding ADC pin. After the A / D conversion is completed, the AD1256 needs to be reset. At the same time, when the working conditions such as the gain and filter settings of the A / D converter change, the converter needs to be recalibrated. The A / D acquisition program flow is as follows Figure 8 and 9 shown.

[0067] When the microprocessor converts the digital signal output by the A / D conversion module into the corresponding torque value, it smoothes the data through the sliding weighted average filtering algorithm. This algorithm can effectively reduce the random noise of the signal and improve the accuracy of the measurement. In practical applications, a queue with a fixed length of N = 12 is defined. Each time a new sampling is performed, the sampled data is placed at the end of the queue, and the data at the head of the original queue is overflowed. In this way, the entire queue always maintains N "latest" data, and then the N data in the queue are averaged as the current sampling value. That is:

[0068]

[0069] In the formula, y n is the output value after filtering of the nth sampling value; x n-i is the ni-th sampling value; c i is the weighting coefficient. In this application, the commonly used weighting coefficient method is adopted, that is, c i =1 / Δ, where Δ=1+e -r +e -2r +…+e -(N-1)r , r is the pure lag time of the control object.

[0070] The microprocessor transmits the calculated torque value to the host computer through the wireless transceiver module. The wireless transceiver module uses the ESP-07S Wi-Fi module, such as Fig.10 As shown in the figure, this module is a powerful and stable Wi-Fi module that supports multiple wireless communication protocols and can meet the needs of high-speed and efficient data transmission. Through this module, the microprocessor can send key data such as torque value to the host computer in real time and accurately, thereby realizing remote monitoring and analysis of data.

[0071] The power module provides a stable power supply for the entire system. Fig.11 and 12 As shown in the figure, the power module includes a SX1308 boost converter, which increases the external input voltage to +5V output, and is used to provide the system with +5V power supply; it also includes a voltage regulator chip, which is used to reduce the +5V voltage output by the SX1308 boost converter to +3.3V, and is used to provide the system with +3.3V power supply. Through such a design, the power module can effectively meet the system's requirements for different voltage levels and ensure the stable operation of the entire system.

[0072] The wireless acquisition system for torsional stress of the elastic shaft of the present application, by adopting wireless transmission technology, effectively solves the problems of layout flexibility and signal attenuation of the traditional wired method, and enhances the reliability of the system. The system uses evenly distributed strain gauge sensors and Wheatstone bridge connections to improve the sensitivity and stability of the measurement, and also has a temperature compensation function. In the signal processing module, through the collaborative work of the differential amplifier unit, the noise suppression unit and the closed-loop regulation unit, not only the stress signal is effectively amplified, but also the signal-to-noise ratio of the signal is significantly improved, eliminating the system error. In particular, the design of the noise suppression unit effectively suppresses the influence of environmental factors and system thermal noise on the torsional stress acquisition signal, and provides high-quality data for subsequent signal processing and analysis. In addition, the system can transmit key data to the host computer in real time and accurately, realize remote monitoring and analysis, and provide strong technical support for evaluating mechanical load status and predicting faults.

[0073] The above is a further detailed description of the present invention in combination with a specific implementation method, and it cannot be determined that the specific implementation of the present invention is limited to this; for technical personnel in the technical field to which the present invention belongs and related technical fields, based on the technical solution of the present invention, the expansion and replacement of operating methods and data should all fall within the protection scope of the present invention.

Claims

1. A wireless acquisition system for elastic shaft torsional stress, characterized in that: include: A stress signal acquisition module, comprising a plurality of strain gauge sensors, each of which is attached to the surface of the elastic shaft to be measured, and is used to detect the mechanical deformation of the elastic shaft, thereby generating an electrical signal proportional to the torque value; A signal processing module, used to amplify the electrical signal, improve the signal-to-noise ratio of the signal, and eliminate system errors; An A / D conversion module, used for converting the output signal of the signal processing module into a digital quantity; A microprocessor, used for receiving the digital signal output by the A / D conversion module, and performing data processing, storage and transmission control; A wireless transceiver module is used to transmit the data processed by the microprocessor to the host computer wirelessly; as well as Power module, used for power supply and management of the entire system; Wherein, the signal processing module includes: A differential amplification unit, used to differentially amplify the output signal of the stress signal acquisition module and add a reference voltage during the amplification process to ensure the stability and accuracy of the signal; A noise suppression unit is used to perform secondary amplitude modulation amplification on the output signal of the differential amplification unit, and add high-frequency filtering and thermal noise suppression processing during the amplification process to enhance the signal-to-noise ratio of the stress acquisition signal; The closed-loop regulation unit is used to perform closed-loop feedback regulation on the two-stage amplification process to eliminate system errors.

2. According to claim 1, a wireless acquisition system for elastic shaft torsional stress is characterized in that: The number of the strain gauge sensors is 4, and they are evenly distributed at intervals of 90° on the circumference of the elastic shaft surface.

3. According to claim 2, a wireless acquisition system for elastic shaft torsional stress is characterized in that: The strain gauge sensors in the stress signal acquisition module are electrically connected in the form of a Wheatstone bridge, and an RC filter is provided at the signal output end of the Wheatstone bridge.

4. According to claim 3, a wireless acquisition system for elastic shaft torsional stress is characterized in that: The differential amplification unit includes an op amp AR1 and an op amp AR2. The in-phase input terminal and the inverting input terminal of the op amp AR1 are connected to the electrical signal output terminal of the stress signal acquisition module. The in-phase input terminal of the op amp AR1 is grounded through a resistor R7. The inverting input terminal of the op amp AR1 is connected to the output terminal of the op amp AR1 through a resistor R8, and is connected to the inverting input terminal and the output terminal of the op amp AR2 through a resistor R9. The in-phase input terminal of the op amp AR2 is connected to a reference power supply through a resistor R10, and is grounded through a parallel resistor R11 and a capacitor C3.

5. According to claim 4, a wireless acquisition system for elastic shaft torsional stress is characterized in that: The noise suppression unit includes an op amp AR3, a non-inverting input terminal of the op amp AR3 is connected to an output terminal of the op amp AR1 through a resistor R12, an inverting input terminal of the op amp AR3 is connected to a resistor R13, a resistor R14, a capacitor C4 and one end of a capacitor C5, the other end of the resistor R13 is connected to the other end of the capacitor C4 and the output terminal of the op amp AR3 through an adjustable resistor RP1, the other ends of the resistor R14 and the capacitor C5 are connected to a drain of a field effect transistor Q1, the source and the gate of the field effect transistor Q1 are grounded, the output terminal of the op amp AR3 is connected to the A / D conversion module through a resistor R15, and is connected to a non-inverting input terminal of the op amp AR1 through the closed-loop adjustment unit.

6. According to claim 5, a wireless acquisition system for elastic shaft torsional stress is characterized in that: The closed-loop regulation unit includes a resistor R16, a resistor R17 and a capacitor C6, one end of the resistor R16 and the capacitor C6 are connected to the output end of the operational amplifier AR3, and the other end of the resistor R16 and the capacitor C6 are connected to the non-inverting input end of the operational amplifier AR1 through the resistor R17.

7. The wireless acquisition system for elastic shaft torsional stress according to claim 6, characterized in that: The A / D conversion module uses an ADS1256 analog-to-digital converter.

8. The wireless acquisition system for elastic shaft torsional stress according to claim 7, characterized in that: The microprocessor is a STC8H1K08-TSSOP20 single chip microcomputer.

9. The wireless acquisition system for elastic shaft torsional stress according to claim 8, characterized in that: The wireless transceiver module uses an ESP-07S Wi-Fi module.

10. The wireless acquisition system for elastic shaft torsional stress according to claim 1, characterized in that: The power module comprises: SX1308 boost converter, which increases the external input voltage to +5V output, is used to provide system +5V power supply; The voltage regulator chip is used to reduce the +5V voltage output by the SX1308 boost converter to +3.3V, so as to provide a +3.3V power supply to the system.

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