A sensor-based signal acquisition and processing circuit and signal acquisition system

Abstract

This invention discloses a sensor-based signal acquisition and processing circuit and a signal acquisition system. The circuit includes a power isolation protection circuit for isolating internal and external power supplies and filtering high-frequency and low-frequency DC signals from the analog signal X output by the sensor to obtain a low-frequency AC signal; an emitter follower circuit for filtering amplitude interference of the low-frequency AC signal caused by the input impedance of subsequent circuits to obtain an output signal X' to be output to the acquisition card; a signal amplification and absolute value circuit for amplifying and processing the output signal X' to obtain a comparison reference voltage for the output signal X'; and a signal trigger filtering circuit for outputting an acquisition trigger signal to the acquisition card based on the comparison reference voltage and a threshold voltage of the output signal X', so that the acquisition card acquires the output signal X' according to the acquisition duration of the acquisition trigger signal. This invention provides a high-quality input signal for the acquisition card signal acquisition, meeting the requirements for high-precision data acquisition.

Description

Technical Field

[0001] This invention relates to the field of sensor signal acquisition technology, and in particular to a sensor-based signal acquisition and processing circuit and signal acquisition system. Background Technology

[0002] In fields such as industrial automation, intelligent manufacturing, and equipment condition monitoring, accurate acquisition and real-time monitoring of equipment operating status are crucial. Typically, equipment operating status is acquired through signals collected by various sensors, which are then processed and analyzed by the acquisition system. This process provides the foundation for condition monitoring, fault diagnosis, and optimized control. However, sensor signals are usually analog signals, often containing significant noise or failing to meet the input standards of the acquisition equipment. Therefore, sensor signals typically require preprocessing through a signal rectification and triggering circuit before being sent to the acquisition card.

[0003] To adapt sensor signals to the requirements of the data acquisition card, they must be shaped and preprocessed by a signal rectification and triggering circuit. The design of the rectification and triggering circuit directly affects the authenticity and accuracy of the acquired signal. For example, when dynamically monitoring high-speed rotating machinery, high-frequency vibration signals need to be precisely shaped, while temperature detection requires filtering and amplifying slowly changing small-amplitude signals. Therefore, the signal rectification and triggering circuit is a crucial preprocessing module in the signal acquisition system, its main function being to amplify, shape, filter, and trigger the raw signal output from the sensor. However, in practical applications, existing signal rectification and triggering circuits still have significant shortcomings, especially in complex industrial environments and scenarios with severe electromagnetic interference, where they cannot completely eliminate noise in the signal, thus affecting the overall performance of the acquisition system and the authenticity of the data. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a sensor-based signal acquisition and processing circuit and signal acquisition system that can significantly improve noise suppression capabilities, provide high-quality input signals for signal acquisition, and meet the high-precision data acquisition requirements in complex environments.

[0005] To achieve the above objectives, the first aspect of the present invention provides a sensor-based signal acquisition and processing circuit, including a power isolation protection circuit, an emitter follower circuit, a signal amplification absolute value circuit, and a signal triggering filtering circuit.

[0006] The power isolation protection circuit is used to isolate internal and external power supplies and filter the high-frequency signal and low-frequency DC signal in the analog signal X output by the sensor to obtain a low-frequency AC signal.

[0007] The emitter follower circuit is used to filter out the amplitude interference of the input impedance of the subsequent circuit on the low-frequency AC signal to obtain the output signal X' to be output to the acquisition card;

[0008] The signal amplification absolute value circuit is used to amplify and perform absolute value processing on the output signal X' to obtain a comparison reference voltage for the output signal X'.

[0009] The signal trigger filtering circuit is used to output a acquisition trigger signal to the acquisition card based on the comparison result of the comparison reference voltage and the threshold voltage of the output signal X', so that the acquisition card acquires the output signal X' according to the acquisition duration of the acquisition trigger signal.

[0010] Furthermore, the power isolation protection circuit includes a power isolation filter circuit and a direct current blocking circuit;

[0011] The power isolation filtering circuit is used to isolate internal and external power supplies and output the analog signal X output by the sensor after digital-to-analog conversion, and filter out high-frequency signals in the analog signal after power isolation.

[0012] The DC blocking circuit is used to filter out the DC in the high-frequency signal to obtain the low-frequency AC signal.

[0013] Furthermore, the power isolation filtering circuit includes an isolation amplifier U1, a resistor R10, and a capacitor C3; the input terminal of the isolation amplifier U1 is connected to the analog signal X, the output terminal of the isolation amplifier U1 is connected to one end of the resistor R10, the other end of the resistor R10 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded.

[0014] Furthermore, the blocking circuit includes capacitors C1 and C2 and resistors R13 and R14. The input terminals of capacitors C1 and C2 are connected in parallel and are respectively connected to one end of resistor R13 and the tap terminal of resistor R10 connected to capacitor C3. The other end of resistor R13 is grounded. The output terminal of capacitors C1 and C2 connected in parallel is connected to one end of resistor R14, and the other end of resistor R14 is grounded.

[0015] Furthermore, the emitter follower circuit includes an operational amplifier U2C and resistors R4 and R11; the first input terminal of the operational amplifier U2C is connected to the output terminal of the parallel connection of capacitors C1 and C2, the second input terminal of the operational amplifier U2C is connected to one end of resistor R4, the output terminal of the operational amplifier U2C is connected to one end of resistor R11, and the other end of resistor R11 is connected to the other end of resistor R4.

[0016] Furthermore, the signal amplification absolute value circuit includes a signal amplification circuit and an absolute value circuit;

[0017] The signal amplification circuit is used to amplify the output signal X' to obtain the amplified signal W;

[0018] The absolute value circuit is used to take the absolute value of the amplified signal W to obtain the comparison reference voltage U0 of the output signal X'.

[0019] Furthermore, the signal triggering filtering circuit includes a threshold voltage adjustment circuit and a trigger signal output circuit.

[0020] The threshold voltage adjustment circuit is used to adjust the magnitude of the threshold voltage;

[0021] The trigger signal output circuit is used to output a data acquisition trigger signal to the data acquisition card based on the comparison result of the comparison reference voltage and the threshold voltage of the output signal X'.

[0022] Furthermore, the threshold voltage adjustment circuit includes operational amplifiers U4A and U4C, resistors R16, R17, R20, R18, R19, R21, R26, and a DIP switch S1, which is adjusted to regulate the threshold voltage.

[0023] Furthermore, the trigger signal output circuit includes comparators U3A and U3D, timer U5, resistor R24, and capacitors C8 and C13.

[0024] A second aspect of the present invention provides a sensor-based signal acquisition system, including a sensor, the signal acquisition and processing circuit described above, and an acquisition card.

[0025] This invention utilizes power isolation, DC blocking and AC passing, and threshold voltage setting circuits to eliminate interference signals. It employs an emitter follower circuit to ensure the reliability of the acquired signal. Through signal amplification circuits, absolute value circuits, multiple threshold voltage selections, and monostable multivibrator control terminals, it ensures good human-machine interaction. The monostable multivibrator is used to determine the signal acquisition time, providing high-quality input signals for the acquisition card and meeting the high-precision data acquisition requirements in complex environments. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a sensor-based signal acquisition and processing circuit according to an embodiment of the present invention;

[0028] Figure 2 for Figure 1 A schematic diagram of a power supply isolation protection circuit;

[0029] Figure 3 for Figure 1 Schematic diagram of the emitter follower circuit and signal amplification circuit;

[0030] Figure 4 for Figure 1 A schematic diagram of an absolute value circuit;

[0031] Figure 5 for Figure 1 A schematic diagram of the threshold voltage adjustment circuit;

[0032] Figure 6 for Figure 1 A schematic diagram of the trigger signal output circuit;

[0033] Figure 7 This is a schematic diagram of a sensor-based signal acquisition system according to an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0035] like Figure 1 As shown, the sensor-based signal acquisition and processing circuit of the present invention includes a power isolation protection circuit 1, an emitter follower circuit 2, a signal amplification absolute value circuit 3, and a signal triggering filtering circuit 4.

[0036] The power isolation protection circuit 1 is used to isolate the internal and external power supplies and filter the high-frequency signal and low-frequency DC signal in the analog signal X output by the sensor to obtain a low-frequency AC signal.

[0037] The emitter follower circuit 2 is used to filter the amplitude interference of the input impedance of the subsequent circuit on the low-frequency AC signal to obtain the output signal X' to be output to the acquisition card;

[0038] The signal amplification absolute value circuit 3 is used to amplify and perform absolute value processing on the output signal X' to obtain a comparison reference voltage for the output signal X';

[0039] The signal triggering filtering circuit 4 is used to output a acquisition trigger signal to the acquisition card according to the comparison result of the comparison reference voltage and the threshold voltage of the output signal X', so that the acquisition card acquires the output signal X' according to the acquisition duration of the acquisition trigger signal.

[0040] In one embodiment of the present invention, such as Figure 2 As shown, the power isolation protection circuit 1 includes a power isolation filter circuit and a direct current blocking circuit;

[0041] The power isolation filtering circuit is used to isolate internal and external power supplies and output the analog signal X output by the sensor after digital-to-analog conversion, and filter out high-frequency signals in the analog signal after power isolation.

[0042] The DC blocking circuit is used to filter out the DC in the high-frequency signal to obtain the low-frequency AC signal.

[0043] Specifically, the power isolation filtering circuit includes an isolation amplifier U1, a resistor R10, and a capacitor C3; the input terminal of the isolation amplifier U1 is connected to the analog signal X, the output terminal of the isolation amplifier U1 is connected to one end of the resistor R10, the other end of the resistor R10 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded.

[0044] The blocking circuit includes capacitors C1 and C2 and resistors R13 and R14. The input terminals of capacitors C1 and C2 are connected in parallel and are respectively connected to one end of resistor R13 and the tap terminal of resistor R10 connected to capacitor C3. The other end of resistor R13 is grounded. The output terminal of capacitors C1 and C2 connected in parallel is connected to one end of resistor R14, and the other end of resistor R14 is grounded.

[0045] To address the complex electromagnetic compatibility environment at the site, an isolation protection circuit was designed with isolation amplifier U1 as its main component. U1 works by electrically isolating the internal circuit power supply from the external circuit power supply. It converts the analog signal X from the external circuit into a digital signal, which passes through the isolation capacitor inside U1, and then back into an analog signal before being transmitted to the internal circuit. When the analog signal X is transmitted to the internal circuit, it couples with the high-frequency signal from U1's digital-to-analog conversion. Therefore, a filter circuit consisting of resistor R10 and capacitor C3 was designed to filter out the high-frequency signal, ensuring the stability of the internal circuit power supply and that signal X meets design specifications. A DC-blocking circuit is formed using components capacitors C1 and C2, and resistors R13 and R14. This circuit guides the acquired low-frequency (DC) signal to ground through resistors R13 and R14, removing the DC component and sending the low-frequency AC signal to the subsequent circuits.

[0046] In one embodiment of the present invention, such as Figure 3As shown, the emitter follower circuit 2 includes an operational amplifier U2C and resistors R4 and R11. The first input terminal of the operational amplifier U2C is connected to the output terminal of capacitors C1 and C2 in parallel. The second input terminal of the operational amplifier U2C is connected to one end of resistor R4. The output terminal of the operational amplifier U2C is connected to one end of resistor R11, and the other end of resistor R11 is connected to the other end of resistor R4. To reduce the influence of the input impedance of subsequent circuits on the amplitude of the output signal X', an emitter follower scheme is adopted, consisting of operational amplifier U2C and R4 and R11. Utilizing the principle of virtual open input of the operational amplifier, the signal X' (amplitude and phase) remains unchanged at pin 12 of U2C. According to the principle of virtual short input of the operational amplifier, the signal at pin 11 of U2C is equal to the signal at pin 12, which ultimately equals the output signal X'.

[0047] In one embodiment of the present invention, such as Figure 3 and 4 As shown, the signal amplification absolute value circuit 3 includes a signal amplification circuit and an absolute value circuit;

[0048] The signal amplification circuit is used to amplify the output signal X' to obtain the amplified signal W;

[0049] The absolute value circuit is used to take the absolute value of the amplified signal W to obtain the comparison reference voltage U0 of the output signal X'.

[0050] Specifically, the signal amplification circuit includes operational amplifier U2D and resistors R3 and R1. The output of operational amplifier U2D amplifies the voltage at signal W:

[0051] u w = (R1+R3) / R3*u X’ The magnification is (R1+R3) / R3

[0052] The amplification factor can be changed by altering the values ​​of resistors R1 and R3, thereby obtaining the specified voltage.

[0053] The absolute value circuit includes operational amplifiers U2A and U2B, resistors R7, R15, R2, R9, R5, R6, and diodes D1, D2, D3, D4. It takes the absolute value of the amplified signal W to obtain a comparison reference voltage U0, which is used to prepare for comparison of the threshold voltage of subsequent circuits.

[0054] In one embodiment of the present invention, such as Figure 5 As shown, the signal triggering filtering circuit 4 includes a threshold voltage adjustment circuit and a trigger signal output circuit.

[0055] The threshold voltage adjustment circuit is used to adjust the magnitude of the threshold voltage;

[0056] The trigger signal output circuit is used to output a data acquisition trigger signal to the data acquisition card based on the comparison result of the comparison reference voltage and the threshold voltage of the output signal X'.

[0057] Specifically, the threshold voltage adjustment circuit includes operational amplifiers U4A and U4C, resistors R16, R17, R20, R18, R19, R21, and R26, and a DIP switch S1. Adjusting the DIP switch adjusts the threshold voltage. The threshold voltage at point Y is controlled by the DIP switch S1. When pins 1 and 8 of the DIP switch are connected, based on the virtual short and virtual open circuit at operational amplifier U4A, the voltage at point V and the current through point V are -R16 / R21*15V and -15 / R21A, respectively. Based on the virtual open and virtual short circuit at operational amplifier U4C, R26 = R19, and the voltage at point Y is R16 / R21*15V. This achieves manual control of the voltage threshold for signal acquisition. If the interference signal, after amplification and absolute value taking, is less than the threshold voltage, the necessary conditions for signal acquisition are not met, thus further filtering out interference signals. The threshold voltage value is adjustable in increments, allowing for changes to the threshold voltage based on specific on-site conditions to ensure reliable signal acquisition.

[0058] The trigger signal output circuit includes comparators U3A and U3D, timer U5, resistor R24, and capacitors C8 and C13. Comparator U3A receives the threshold voltage at point Y and the comparison reference voltage U0 of the rectified and amplified signal. When the comparison reference voltage U0 is greater than the threshold voltage at point Y, pin 2 of the comparator U3A output is grounded, the left side of capacitor C8 is grounded (the voltage across the capacitor cannot change abruptly), and the right side of C8 is grounded. At this time, pin 2 of timer U5 receives a falling edge signal. When the comparison reference voltage U0 is less than the threshold voltage at point Y, pin 2 of the comparator U3A output is in a high-impedance state, and the voltage of C8 remains unchanged. Timer U5, resistor R24, and capacitors C12 and C13 form a monostable multivibrator. To prevent malfunctions caused by harsh electromagnetic compatibility environments and spatial interference at the data acquisition site, manual intervention buttons S2 and S3 are set on pin 4 (RESET) of timer U5. When S2 is closed and S3 is open, pin 4 (RESET) of timer U5 is high, and pin 3 of U5 is forcibly set to 0, meaning the data acquisition card does not acquire signals. When S3 is closed and S2 is open, pin 4 (RESET) of timer U5 is low, and pin 3 of U5 outputs according to the output determination. When pin 2 of timer U5 receives a falling edge trigger, pin 3 outputs a high level for a duration t = 1.1R24*C12. The duration of the high level can be controlled by modifying the resistor and capacitor values. Comparator U3D receives the comparison voltage at pin 10 and the high-level signal from the monostable multivibrator at pin 11. The comparison voltage is 5V, derived from the 15V voltage divided by resistors R35 and R37, i.e., comparison voltage = R37 / (R37+R35)*15V. The comparison voltage can be adjusted according to the actual situation at the site. When the monostable multivibrator outputs a high level, the voltage at pin 11 of comparator U3D is greater than the voltage at pin 10, resulting in a high-impedance output. The voltage at pin 13 of comparator U3D is equal to μV for a duration of 1.1R24*C12. At this time, the acquisition card receives a high-level voltage lasting 1.1R24*C12s, and the acquisition card acquires the X' signal for 1.1R24*C12s.

[0059] like Figure 7 As shown, the sensor-based signal acquisition system of the present invention includes a sensor, a signal rectification trigger circuit, and a data acquisition card. The signal acquired by the sensor is processed by the signal rectification trigger circuit, which outputs a trigger signal and a processed acquisition signal X' to the data acquisition card. The data acquisition card acquires the processed acquisition signal X' according to the acquisition duration of the trigger signal.

[0060] In summary, this invention, based on the harsh electromagnetic compatibility environment, presents a method to eliminate interference signals by utilizing power supply isolation, DC blocking and AC passing, and setting threshold voltages. An emitter follower ensures the reliability of the acquired signal. Signal amplification circuits, absolute value circuits, multiple threshold voltage selections, and a monostable multivibrator RESET control terminal ensure good human-machine interaction. The monostable multivibrator determines the acquisition time. This invention features ingenious circuit design, low-cost components, 100% domestic production, and adjustable settings, facilitating widespread adoption.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sensor-based signal acquisition and processing circuit, characterized in that, This includes a power isolation protection circuit, an emitter follower circuit, a signal amplification absolute value circuit, and a signal triggering filtering circuit; The power isolation protection circuit includes a power isolation filter circuit and a direct current blocking circuit; The power isolation and filtering circuit includes an isolation amplifier U1, a resistor R10, and a capacitor C3. The input terminal of the isolation amplifier U1 is connected to the analog signal X output by the sensor. The output terminal of the isolation amplifier U1 is connected to one end of the resistor R10, the other end of the resistor R10 is connected to one end of the capacitor C3, and the other end of the capacitor C3 is grounded to isolate the internal and external power supplies and filter out high-frequency signals. The DC blocking circuit includes capacitors C1 and C2 and resistors R13 and R14. Capacitors C1 and C2 are connected in parallel, and their parallel input terminals are respectively connected to one end of resistor R13 and the tap terminal where resistor R10 is connected to capacitor C3. The other end of resistor R13 is grounded. The output terminal of capacitors C1 and C2 connected in parallel is connected to one end of resistor R14, and the other end of resistor R14 is grounded, so as to filter out the DC component and obtain a low-frequency AC signal. The emitter follower circuit is used to filter out the amplitude interference of the input impedance of the subsequent circuit on the low-frequency AC signal to obtain the output signal X' to be output to the acquisition card; The signal amplification absolute value circuit includes a signal amplification circuit and an absolute value circuit. The signal amplification circuit is used to amplify the output signal X' to obtain an amplified signal W, and the absolute value circuit is used to take the absolute value of the amplified signal W to obtain the comparison reference voltage U0 of the output signal X'. The signal triggering filtering circuit includes a threshold voltage adjustment circuit and a trigger signal output circuit. The threshold voltage adjustment circuit includes a DIP switch S1, which is used to adjust the threshold voltage in increments by adjusting the DIP switch S1. The trigger signal output circuit includes a comparator U3A, a timer U5, a resistor R24, a capacitor C12, and a capacitor C13. The comparator U3A is used to receive the comparison reference voltage U0 and the threshold voltage, and when the comparison reference voltage U0 is greater than the threshold voltage, it causes the trigger terminal of the timer U5 to receive a falling edge trigger signal. The timer U5, resistor R24, capacitor C12, and capacitor C13 form a monostable multivibrator. Under the action of the falling edge trigger signal, the monostable multivibrator outputs a acquisition trigger signal with a predetermined duration, which is 1.1R24*C12, so that the acquisition card can acquire the output signal X' within the predetermined duration.

2. The signal acquisition and processing circuit as described in claim 1, characterized in that, The emitter follower circuit includes an operational amplifier U2C and resistors R4 and R11; the first input terminal of the operational amplifier U2C is connected to the output terminal of capacitors C1 and C2 in parallel, the second input terminal of the operational amplifier U2C is connected to one end of resistor R4, the output terminal of the operational amplifier U2C is connected to one end of resistor R11, and the other end of resistor R11 is connected to the other end of resistor R4.

3. The signal acquisition and processing circuit as described in claim 1, characterized in that, The threshold voltage adjustment circuit includes operational amplifiers U4A and U4C, resistors R16, R17, R20, R18, R19, R21, and R26, and a DIP switch S1. Adjusting the DIP switch adjusts the magnitude of the threshold voltage.

4. A sensor-based signal acquisition system, characterized in that, It includes a sensor, a signal acquisition and processing circuit as described in any one of claims 1-3, and a data acquisition card.

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