Method and system for rapid attenuation after half-amplitude frequency point of acceleration sensor
By combining hardware acquisition circuits and software algorithms, the problem of the accelerometer signal failing to attenuate quickly after the half-amplitude frequency point was solved, achieving rapid signal attenuation and improving the safety and reliability of rail trains.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU CHANGFENG AVIATION ELECTRONICS
- Filing Date
- 2025-12-17
- Publication Date
- 2026-05-05
AI Technical Summary
Existing accelerometers cannot quickly attenuate their output signals after the half-amplitude frequency point, leading to the risk of misjudgment and affecting the safety and reliability of rail trains.
A method combining hardware signal retrieval circuit and software sampling comparison analysis algorithm is adopted, and the signal is rapidly attenuated after the half-amplitude frequency point through analog filtering circuit and attenuation control circuit.
Without affecting the signal quality within the effective frequency band, rapid signal attenuation after the half-amplitude frequency point is achieved, reducing the risk of misjudgment and improving the safety and reliability of rail trains.
Smart Images
Figure CN121979018A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of rail transit sensor signal processing technology, and relates to a method and system for rapid attenuation of the output signal after the half-amplitude frequency point of an accelerometer. This method can be used in a sensor system for monitoring the lateral acceleration of a rail train bogie to rapidly attenuate the output signal after the half-amplitude frequency point. Background Technology
[0002] The lateral acceleration sensor for rail trains is mainly used to collect the acceleration value of the bogie in the lateral direction (perpendicular to the direction of train travel) during train operation. This is to determine whether the train's lateral acceleration has increased abnormally due to excessive speed when turning on a curve, thus posing a risk of derailment. This sensor is a key component of the rail train braking and safety monitoring system.
[0003] However, trains experience vibrations during actual operation. Although the accelerometer chip (such as a MEMS chip) itself has good high-frequency vibration response characteristics and its output signal is relatively stable within a certain frequency range, the sensor system usually integrates analog circuits such as DACs, filters, and amplifiers. These analog circuits, limited by their own frequency response characteristics, cause the output signal amplitude to gradually attenuate as the vibration frequency increases, resulting in a deviation between the acceleration value output by the accelerometer and the actual value. Especially after reaching a certain frequency—the half-amplitude frequency point (the frequency corresponding to the output signal amplitude attenuating to half the static output voltage without vibration)—if the attenuated signal is still output in the conventional manner, it is very easy for the host computer to misinterpret it as a valid acceleration event, thus triggering erroneous braking or alarms.
[0004] Currently, the industry standard practice is to rapidly lower the amplitude of the output signal to minimize output and avoid misinterpretation by the sensor signal acquisition host. However, unlike DACs and filters, sensor chips have good vibration frequency response characteristics. The signal output by the chip is relatively stable at a certain vibration frequency. Although the signal is attenuated after processing by DACs and filters, it cannot attenuate to the desired value after the specified frequency point. Traditional high-order filtering schemes can only control the attenuation amplitude to a limited extent. The slow attenuation process cannot fully achieve the expected effect. Furthermore, if the filter order is increased indiscriminately, it may cause oscillations in the output amplitude, making the frequency response curve very uneven.
[0005] Therefore, in the face of this problem, there is an urgent need to study solutions from both hardware and software perspectives to achieve both high-fidelity output of the sensor's main chip within the effective frequency band and proactive, fast, and reliable suppression of the output signal after exceeding the half-amplitude frequency point, thereby fundamentally solving the problem of misjudgment caused by high-frequency vibration interference. Summary of the Invention
[0006] To address the technical problem that the output signal of an accelerometer cannot rapidly decay at specific frequency points, especially after the half-amplitude output frequency point, this invention discloses a method for rapid decay of the accelerometer after the half-amplitude frequency point. This method is designed by integrating the hardware retrieval circuit of the output signal and the software sampling comparison analysis algorithm.
[0007] Specifically, the method includes the following steps: S1. Acquire the raw digital signal output by the accelerometer chip and convert the raw digital signal into an analog signal; S2. The analog signal is processed by an analog filter circuit with a preset cutoff frequency, so that at the preset cutoff frequency, the voltage amplitude of the analog signal is attenuated to half of the effective output amplitude under vibration-free conditions, and the preset cutoff frequency is defined as the half amplitude frequency point. S3. Monitor the sampled analog signal output by the analog filter circuit, convert the sampled analog signal into a sampled digital signal, and determine whether the system is in a working state exceeding half the amplitude frequency point based on the amplitude comparison result between the sampled digital signal and the original digital signal. S4. When the system is determined to be operating at a frequency exceeding half the amplitude, the attenuation control mechanism is triggered, causing the sensor's final analog output signal to rapidly attenuate to zero level.
[0008] Further, in step S3, determining whether the system is operating at a frequency exceeding half the amplitude value includes: S31. Set a sampling point at the output end of the analog filter circuit to collect the sampling analog signal in real time, and convert the sampling analog signal into a sampling digital signal. S32. Comparing the amplitude of the acquired digital signal with that of the original digital signal, including: If the amplitude of the sampled digital signal is less than or equal to half the amplitude of the original digital signal in multiple consecutive sampling periods, the system is determined to be in a working state at a frequency point exceeding half the amplitude. If, within multiple consecutive sampling periods, the amplitude of the resampled digital signal is greater than half the amplitude of the original digital signal, then the system is determined to be operating at a frequency point not exceeding half the amplitude.
[0009] Furthermore, the number of consecutive sampling periods is no less than three.
[0010] Furthermore, in step S4, the final analog output signal of the sensor is rapidly attenuated to zero level, including: S41. When the system is determined to be operating at a frequency point exceeding half the amplitude, the attenuation control mechanism is triggered to respond, and the microcontroller unit (MCU) outputs an attenuation control signal to the attenuation control circuit. S42. The attenuation control circuit, according to the attenuation control signal, forces the output of the operational amplifier circuit to be pulled down to the reference ground level, so that the final analog output signal of the sensor is rapidly attenuated to zero level.
[0011] Furthermore, the attenuation control circuit includes an analog switch driven by the GPIO pin of the microcontroller unit (MCU), with its signal terminal connected to the output of the operational amplifier circuit and its ground terminal connected to system ground.
[0012] In an improved embodiment of the above-described method for rapid attenuation after the half-amplitude frequency point of the accelerometer, the method further includes: S5. When it is determined that the system has not been in a working state at a frequency point exceeding half the amplitude value within the preset recovery time period, the normal signal output of the sensor is restored.
[0013] This invention also provides a system for rapid decay of accelerometer amplitude after the half-amplitude frequency point, comprising: An accelerometer chip is used to acquire acceleration and output raw digital signals; The microcontroller unit (MCU) has its SPI communication port connected to the data output terminal of the acceleration sensing unit, and is used to receive and process the raw digital signal. The digital-to-analog converter (DAC) has its input terminal connected to the digital signal output port of the microcontroller unit (MCU) and is used to convert the processed digital signal into an analog signal. An analog filter circuit, whose input is connected to the output of the digital-to-analog converter (DAC), performs frequency response shaping on the received analog signal and sets the half-amplitude frequency point. An operational amplifier circuit, whose input terminal is connected to the output terminal of the analog filter circuit, is used to amplify the signal amplitude to meet the required voltage value; The attenuation control sampling circuit has its sampling terminal connected to the node between the output terminal of the analog filter circuit and the input terminal of the operational amplifier circuit, and its output terminal connected to the analog-to-digital converter (AD) input pin of the microcontroller unit (MCU) for acquiring the filtered analog signal. The attenuation control circuit has its control terminal connected to the GPIO output pin of the microcontroller unit (MCU), its signal terminal connected to the output terminal of the operational amplifier circuit, and its ground terminal connected to the system ground. It is used to pull the final output signal down to 0V under the instruction of the MCU.
[0014] Furthermore, the attenuation control circuit includes a single-pole double-throw analog switch, whose control pin is connected to the GPIO output pin of the microcontroller unit (MCU), whose signal terminal is connected to the output terminal of the operational amplifier circuit, and whose ground terminal is connected to system ground.
[0015] Furthermore, the system also includes an LDO power chip, whose input is connected to an external DC24V power supply, and whose output is connected to the power pins of the microcontroller unit (MCU), the digital-to-analog converter (DAC), and the accelerometer unit, respectively, to provide a stable operating voltage.
[0016] Furthermore, the analog filter circuit is a second-order low-pass filter circuit.
[0017] The method, circuit, and system of this invention, based on controlling the half-amplitude output frequency point at the frequency point value required by the signal acquisition host, can further attenuate the frequency band above the half-amplitude frequency point according to the control requirements of the signal acquisition host system, and can directly attenuate to no signal output. Compared with the traditional method of attenuation control relying only on analog high-order filter circuits, it has better effect, higher attenuation amplitude, and will not affect the effective frequency band, especially the normal value output before the half-amplitude frequency point. Attached Figure Description
[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a system architecture diagram of the accelerometer sensor of the present invention, showing rapid decay after the half-amplitude frequency point. Figure 2 This is a circuit block diagram of a rapid attenuation system after the half-amplitude frequency point of an accelerometer, provided for specific implementation. Figure 3 A comparison of frequency response curves before and after adding an attenuation control retrieval circuit to the system; Figure 4 This is a flowchart of the method for rapid attenuation after the half-amplitude frequency point of the accelerometer according to the present invention. Detailed Implementation
[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.
[0021] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features of the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0022] This invention provides a system for rapid attenuation after the half-amplitude frequency point of an accelerometer, see [link to relevant documentation]. Figure 1 As shown, the system includes an accelerometer chip, a microcontroller unit (MCU), a digital-to-analog converter (DAC), an analog filter circuit, and an operational amplifier circuit.
[0023] The accelerometer chip is used to acquire acceleration and output raw digital signals. This chip features high accuracy, strong stability, and excellent vibration and electromagnetic interference resistance, serving as the main chip for acceleration signal acquisition. However, in a vibration environment, the output amplitude of this digital chip cannot respond to the frequency response curve as expected compared to an analog chip. Therefore, to better achieve the desired vibration frequency response curve characteristics and meet the requirements of the sensor signal acquisition host for analog signal format, this invention adopts a scheme of digital sensor chip + analog conversion circuit. Specifically, it uses a digital signal output sensor chip, MCU, DAC device, analog filter circuit, operational amplifier circuit, etc., for the main circuit system design. Leveraging the MCU's ability to integrate software algorithms, it further integrates a signal output retrieval circuit, a signal amplitude attenuation analysis algorithm, and a signal output control circuit to achieve control of the half-amplitude output frequency point. This solves the problem of rapid signal attenuation after the half-amplitude output frequency point required by the accelerometer signal acquisition host computer, and can directly attenuate the signal output to 0V, i.e., no output.
[0024] Specifically, such as Figure 1As shown, the SPI or other word-type communication ports of the microcontroller unit (MCU) are connected to the data output terminal of the accelerometer sensor unit to receive and process the raw digital signal. The input terminal of the digital-to-analog converter (DAC) is connected to the digital signal output port of the MCU to convert the processed digital signal into an analog signal. The input terminal of the analog filter circuit is connected to the output terminal of the DAC to perform frequency response shaping on the received analog signal and set the half-amplitude frequency point. The input terminal of the operational amplifier circuit is connected to the output terminal of the analog filter circuit to amplify the signal amplitude to meet the required voltage value before output.
[0025] Through the processing of the above components, the output voltage value, under vibration conditions, can only guarantee that the frequency point of the half-amplitude output meets the requirements of the signal acquisition host. However, the requirement for rapid attenuation of the output amplitude after the half-amplitude output frequency point cannot be met. Therefore, based on the main circuit of the above digital-to-analog conversion, filtering, and amplification circuits, as follows... Figure 1 As shown, this invention sets up an attenuation control sampling circuit and an attenuation control circuit, and designs a corresponding signal amplitude attenuation comparison analysis algorithm to process the output amplitude after the half-amplitude frequency point, which satisfies the requirement of rapid attenuation and ensures the normal output of the signal before the half-amplitude frequency point.
[0026] The sampling terminal of the attenuation control retrieval circuit is connected to the node between the output terminal of the analog filter circuit and the input terminal of the operational amplifier circuit. Its output terminal is connected to the analog-to-digital converter (AD) input pin of the microcontroller unit (MCU) for acquiring the filtered analog signal. The control terminal of the attenuation control circuit is connected to the GPIO output pin of the MCU, its signal terminal is connected to the output terminal of the operational amplifier circuit, and its ground terminal is connected to system ground, used to pull the final output signal low to 0V under MCU command. The effects of adding the attenuation control retrieval circuit and the attenuation control circuit before and after are compared as follows: Figure 3 As shown, where, Figure 3 (a) shows the frequency response curve before the addition of data acquisition control, and (b) shows the frequency response curve after the addition of data acquisition control. The horizontal axis represents the vibration frequency, and the vertical axis represents the signal amplitude. From (a), it can be seen that without data acquisition and control, the half-amplitude frequency point of the accelerometer decays slowly. From (b), it can be seen that after data acquisition and control, the half-amplitude frequency point of the accelerometer decays rapidly to zero.
[0027] More specifically, the working principle of the attenuation control retrieval circuit and the attenuation control circuit is as follows: (1) Since the signal attenuation is mainly caused by the DAC and the second-order filter circuit under vibration environment, the signal retrieval point is set after the output of the second-order filter circuit, and the retrieval analog signal is provided to the retrieval channel DAC or the AD sampling channel built into the MCU.
[0028] (2) The attenuated signal in the retrieval channel DAC or the AD module built into the MCU is used to perform analog-to-digital conversion, and the converted digital signal is provided to the MCU through digital interfaces such as SPI.
[0029] (3) The MCU compares the converted and sampled digital signal with the digital signal provided to the main channel DAC. To prevent comparison errors and misjudgments, the comparison analysis algorithm incorporates time judgment. When the sampled digital signal value is continuously judged to be less than 1 / 2 of the digital signal value provided by the MCU to the main channel DAC for a certain period of time (the time length can be set according to actual needs), a control signal is provided to the signal output control circuit to directly pull the signal down to 0V, thereby achieving the purpose of rapid attenuation.
[0030] (4) The signal output control circuit is equipped with a switching circuit, which can be a controllable switching device such as a relay or a module switch. The MCU can control the switching circuit through the IO port or digital communication interface. The switching circuit is at least a dual-channel control switch, one channel is used to output the normal sensor signal, and the other channel can directly pull the sensor signal output low to the signal ground. That is, before the sampled signal reaches 1 / 2 of the actual output signal, the MCU controls the switching circuit to output the sensor signal normally after the operational amplifier circuit; when it is determined that the sampled signal is lower than 1 / 2 of the normal sensor signal output, the MCU controls the signal output control circuit to operate, so that the final sensor output signal is directly pulled low to the signal ground, that is, output 0V.
[0031] (4) When the vibration weakens, that is, when the vibration frequency recovers to within half the amplitude frequency point, the MCU detects that the amplitude of the signal provided by the attenuation control sampling circuit after second-order filtering recovers to within 1 / 2 of the normal output signal amplitude of the sensor within a certain period of time. Then the control signal output control circuit is activated, and the sensor signal output by the operational amplifier circuit is output normally.
[0032] In one embodiment, such as Figure 2As shown, the analog filtering circuit preferentially uses a second-order low-pass filter circuit. The accelerometer chip is a three-axis accelerometer chip, model SCA3300-D01. The MCU uses an STM32 microcontroller based on an ARM core, and is designed with necessary power conversion, digital-to-analog conversion, operational amplification, and filtering circuits. To control the rapid attenuation after the half-amplitude output frequency point under vibration conditions, it integrates a sampling circuit based on STM32 microcontroller AD sampling and a signal output control circuit based on an analog switch, along with a sampling comparison analysis algorithm, to achieve the signal attenuation characteristics required by the rail transit vehicle system under vibration conditions. It mainly consists of modules such as input / output interfaces, power conversion circuits, sensor chip and peripheral circuits, ARM chip and peripheral circuits, digital-to-analog conversion circuits, amplification and filtering circuits, sampling circuits, and attenuation control circuits.
[0033] In one embodiment, the attenuation control circuit includes a single-pole double-throw analog switch, whose control pin is connected to the GPIO output pin of the microcontroller unit (MCU), whose signal terminal is connected to the output terminal of the operational amplifier circuit, and whose ground terminal is connected to system ground.
[0034] In one embodiment, such as Figure 2 As shown, the system also includes an LDO power chip, whose input is connected to an external DC24V power supply to convert the DC24V power provided by the train onboard system into the power supply required by each module on the board. Its output is connected to the power pins of the microcontroller unit (MCU), the digital-to-analog converter (DAC), and the acceleration sensing unit, respectively, to provide a stable operating voltage.
[0035] This invention also provides a method for rapid attenuation of the accelerometer signal after the half-amplitude frequency point. This method, through a collaborative mechanism of feedback acquisition, intelligent criteria, and active attenuation control, achieves rapid zeroing of the output signal after the half-amplitude frequency point without sacrificing measurement accuracy in vibration-free environments, effectively avoiding misjudgment of high-frequency vibration interference by the vehicle-mounted host. Specifically, the method can be implemented using the aforementioned system, such as... Figure 4 As shown, it includes the following steps: S1. Acquire the raw digital signal output by the accelerometer chip and convert the raw digital signal into an analog signal; S2. The analog signal is processed by an analog filter circuit with a preset cutoff frequency, so that at the preset cutoff frequency, the voltage amplitude of the analog signal is attenuated to half of the effective output amplitude under vibration-free conditions, and the preset cutoff frequency is defined as the half amplitude frequency point. S3. Monitor the sampled analog signal output by the analog filter circuit, convert the sampled analog signal into a sampled digital signal, and determine whether the system is in a working state exceeding half the amplitude frequency point based on the amplitude comparison result between the sampled digital signal and the original digital signal. S4. When the system is determined to be operating at a frequency exceeding half the amplitude, the attenuation control mechanism is triggered, causing the sensor's final analog output signal to rapidly attenuate to zero level.
[0036] In one example of step S3 above, determining whether the system is operating at a frequency exceeding half the amplitude value includes: S31. Set a sampling point at the output end of the analog filter circuit to collect the sampling analog signal in real time, and convert the sampling analog signal into a sampling digital signal. S32. Comparing the amplitude of the acquired digital signal with that of the original digital signal, including: If the amplitude of the sampled digital signal is less than or equal to half the amplitude of the original digital signal in multiple consecutive sampling periods, the system is determined to be in a working state at a frequency point exceeding half the amplitude. If, within multiple consecutive sampling periods, the amplitude of the resampled digital signal is greater than half the amplitude of the original digital signal, then the system is determined to be operating at a frequency point not exceeding half the amplitude.
[0037] The number of consecutive sampling periods is no less than three.
[0038] In one example of step S4 above, rapidly attenuating the sensor's final analog output signal to zero level includes: S41. When the system is determined to be operating at a frequency point exceeding half the amplitude, the attenuation control mechanism is triggered to respond, and the microcontroller unit (MCU) outputs an attenuation control signal to the attenuation control circuit. S42. The attenuation control circuit, according to the attenuation control signal, forces the output of the operational amplifier circuit to be pulled down to the reference ground level, so that the final analog output signal of the sensor is rapidly attenuated to zero level.
[0039] The attenuation control circuit includes an analog switch, which is driven by the GPIO pin of a microcontroller unit (MCU). Its signal terminal is connected to the output of the operational amplifier circuit, and its ground terminal is connected to the system ground.
[0040] In an improved embodiment of the above-mentioned method for rapid attenuation after the half-amplitude frequency point of the accelerometer, such as... Figure 4 As shown, the method further includes: S5. When it is determined that the system has not been in a working state at a frequency point exceeding half the amplitude value within the preset recovery time period, the normal signal output of the sensor is restored.
[0041] The embodiments of the present invention achieve the following technical effects: 1. Compared to traditional solutions that rely on the natural roll-off characteristics of analog filters, even with high-order designs, their attenuation rate remains limited, making it difficult to quickly suppress the output after the half-amplitude frequency point. The method of this invention, once it determines that the vibration frequency exceeds the half-amplitude frequency point, immediately drives the attenuation control circuit to force the final output down to zero, resulting in an attenuation speed far exceeding the limits achievable by any passive or active filter.
[0042] 2. In rail transit applications, if high-frequency vibration interference is mistakenly identified as a valid lateral acceleration signal, it may trigger unnecessary emergency braking or derailment warnings. The method of this invention ensures that signals exceeding half-amplitude frequency points are completely ignored, fundamentally eliminating the risk of misjudgment by the host computer due to vibration interference, and significantly improving the safety and reliability of train operation.
[0043] 3. This invention sets the sampling point after the analog filter circuit and before the operational amplifier circuit, and the attenuation execution point is located at the final output terminal. This ensures that attenuation control only applies to high-frequency invalid signals, without interfering with the original signal acquisition and processing links in a vibration-free environment. Within the effective operating frequency band below the half-amplitude frequency point, the sensor maintains high linearity and high fidelity output characteristics, fully meeting the dynamic response requirements of railway vehicle electronic equipment standards such as EN 50155.
[0044] 4. In this invention, a time continuity criterion (such as satisfying the amplitude threshold condition for ≥3 consecutive sampling periods) is introduced as a prerequisite for triggering attenuation, which effectively filters out occasional amplitude fluctuations caused by instantaneous impacts or noise and avoids false triggering; at the same time, the recovery mechanism also adopts a similar criterion to ensure that the system state switching is smooth and reliable.
[0045] 5. The design of the method of the present invention does not use traditional high-order filtering methods, which can avoid problems such as passband oscillation and phase nonlinearity caused by excessively high Q (Quality Factor) values. It makes the overall amplitude-frequency characteristics flat in the effective frequency band and steeply decrease after the cutoff point, which balances measurement accuracy and anti-interference ability, and is superior to existing pure analog filtering schemes.
[0046] 6. The system of this invention does not require the use of complex high-order filters or expensive anti-vibration chips. It can achieve high-performance attenuation control using only conventional MCUs, DACs, analog switches and simple sampling circuits. The hardware cost is low, the software logic is clear, and it is easy to upgrade and deploy on the basis of existing sensor platforms.
[0047] Obviously, those skilled in the art should understand that the steps of the above-described embodiments of the present invention can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using device-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented here, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the embodiments of the present invention are not limited to any particular combination of hardware and software.
[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of 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 method for rapid attenuation after the half-amplitude frequency point of an accelerometer, characterized in that, include: Acquire the raw digital signal output by the accelerometer chip and convert the raw digital signal into an analog signal; The analog signal is processed by an analog filter circuit with a preset cutoff frequency, so that at the preset cutoff frequency, the voltage amplitude of the analog signal is attenuated to half of the effective output amplitude under vibration-free conditions, and the preset cutoff frequency is defined as the half amplitude frequency point. The system monitors the analog signal output by the analog filter circuit, converts the analog signal into a digital signal, and determines whether the system is operating at a frequency point exceeding half the amplitude based on the amplitude comparison between the digital signal and the original digital signal. When the system is determined to be operating at a frequency exceeding half the amplitude, the attenuation control mechanism is triggered, causing the sensor's final analog output signal to rapidly attenuate to zero level.
2. The method for rapid attenuation after the half-amplitude frequency point of an accelerometer according to claim 1, characterized in that, Determining whether the system is operating at a frequency exceeding half the amplitude value includes: A sampling point is set at the output of the analog filter circuit to collect the analog signal in real time, and the analog signal is converted into a digital signal. Comparing the amplitude of the acquired digital signal with that of the original digital signal includes: If the amplitude of the sampled digital signal is less than or equal to half the amplitude of the original digital signal in multiple consecutive sampling periods, the system is determined to be in a working state at a frequency point exceeding half the amplitude. If, within multiple consecutive sampling periods, the amplitude of the resampled digital signal is greater than half the amplitude of the original digital signal, then the system is determined to be operating at a frequency point not exceeding half the amplitude.
3. The method for rapid attenuation after the half-amplitude frequency point of an accelerometer according to claim 2, characterized in that, The number of consecutive sampling periods shall not be less than three.
4. The method for rapid attenuation after the half-amplitude frequency point of an accelerometer according to claim 1, characterized in that, To rapidly decay the sensor's final analog output signal to zero, the following methods are employed: When the system is determined to be operating at a frequency point exceeding half the amplitude, the attenuation control mechanism is triggered to respond, and the microcontroller unit (MCU) outputs an attenuation control signal to the attenuation control circuit. The attenuation control circuit, based on the attenuation control signal, forces the output of the operational amplifier circuit to be pulled low to the reference ground level, so that the final analog output signal of the sensor is rapidly attenuated to zero level.
5. The method for rapid attenuation after the half-amplitude frequency point of an accelerometer according to claim 4, characterized in that, The attenuation control circuit includes an analog switch, which is driven by the GPIO pin of a microcontroller unit (MCU). Its signal terminal is connected to the output of an operational amplifier circuit, and its ground terminal is connected to system ground.
6. The method for rapid attenuation after the half-amplitude frequency point of an accelerometer according to any one of claims 1 to 5, characterized in that, Also includes: When the system determines that it has not been in a working state at a frequency point exceeding half the amplitude value within the preset recovery time period, the normal signal output of the sensor is restored.
7. A system for rapid attenuation after the half-amplitude frequency point of an accelerometer, characterized in that, include: An accelerometer chip is used to acquire acceleration and output raw digital signals; The microcontroller unit (MCU) has its SPI communication port connected to the data output terminal of the acceleration sensing unit, and is used to receive and process the raw digital signal. The digital-to-analog converter (DAC) has its input terminal connected to the digital signal output port of the microcontroller unit (MCU) and is used to convert the processed digital signal into an analog signal. An analog filter circuit, whose input is connected to the output of the digital-to-analog converter (DAC), performs frequency response shaping on the received analog signal and sets the half-amplitude frequency point. An operational amplifier circuit, whose input terminal is connected to the output terminal of the analog filter circuit, is used to amplify the signal amplitude to meet the required voltage value; The attenuation control sampling circuit has its sampling terminal connected to the node between the output terminal of the analog filter circuit and the input terminal of the operational amplifier circuit, and its output terminal connected to the analog-to-digital converter (AD) input pin of the microcontroller unit (MCU) for acquiring the filtered analog signal. The attenuation control circuit has its control terminal connected to the GPIO output pin of the microcontroller unit (MCU), its signal terminal connected to the output terminal of the operational amplifier circuit, and its ground terminal connected to the system ground. It is used to pull the final output signal down to 0V under the instruction of the MCU.
8. The system for rapid attenuation after the half-amplitude frequency point of an accelerometer according to claim 7, characterized in that, The attenuation control circuit includes a single-pole double-throw analog switch, whose control pin is connected to the GPIO output pin of the microcontroller unit (MCU), whose signal terminal is connected to the output terminal of the operational amplifier circuit, and whose ground terminal is connected to the system ground.
9. The system for rapid attenuation after the half-amplitude frequency point of an accelerometer according to claim 7, characterized in that, It also includes an LDO power chip, whose input is connected to an external DC24V power supply, and whose output is connected to the power pins of the microcontroller unit (MCU), the digital-to-analog converter (DAC), and the accelerometer unit, respectively, to provide a stable operating voltage.
10. The system for rapid attenuation after the half-amplitude frequency point of an accelerometer according to claim 7, characterized in that, The analog filter circuit is a second-order low-pass filter circuit.