CN-121979018-A - Method and system for rapid attenuation of acceleration sensor after half-amplitude frequency point

CN121979018ACN 121979018 ACN121979018 ACN 121979018ACN-121979018-A

Abstract

The invention belongs to the technical field of signal processing of rail transit sensors, and provides a method and a system for rapid attenuation after a half-amplitude frequency point of an acceleration sensor, wherein the method comprises the steps of converting an acquired original digital signal into an analog signal; setting a half-amplitude frequency point through an analog filter circuit, extracting a filtered signal and comparing the filtered signal with an original digital signal to judge whether the system is in a working state exceeding the half-amplitude frequency point, triggering an attenuation control circuit to pull down the output to a zero level if the system is in the working state exceeding the half-amplitude frequency point, and carrying out normal output after the system is not in the recovery time period. The system comprises an acceleration sensor chip, an MCU, a DAC, an analog filter circuit, an operational amplifier circuit, an attenuation control stoping circuit and an attenuation control circuit. The method and the system realize the rapid return to zero of the output signal after exceeding the half-amplitude frequency point, have steep attenuation and no influence on the effective frequency band, and are suitable for high-reliability scenes such as rail transit.

Inventors

LIU JIANTAO
REN YANKUN
XU FUPING
Miao tengfei
JIANG CHENHAO

Assignees

苏州长风航空电子有限公司

Dates

Publication Date: 20260505
Application Date: 20251217

Claims (10)

1. A method for rapid decay after half-amplitude frequency points of an acceleration sensor, comprising: acquiring an original digital signal output by an acceleration sensor chip, and converting the original digital signal into an analog signal; Processing the analog signal through an analog filter circuit with a preset cut-off frequency, so that at the preset cut-off frequency, the voltage amplitude of the analog signal is attenuated to be half of the effective output amplitude in a vibration-free environment, and the preset cut-off frequency is defined as a half-amplitude frequency point; Monitoring a stoping analog signal output by the analog filter circuit, converting the stoping analog signal into a stoping digital signal, and judging whether a system is in a working state exceeding a half-amplitude frequency point or not based on an amplitude comparison result of the stoping digital signal and the original digital signal; when the system is judged to be in a working state exceeding a half-amplitude frequency point, an attenuation control mechanism is triggered, so that the final analog output signal of the sensor is rapidly attenuated to a zero level.
2. The method for rapid decay after half-amplitude frequency point of an acceleration sensor of claim 1, wherein determining whether the system is in an operational state exceeding the half-amplitude frequency point comprises: setting a stoping point at the output end of the analog filter circuit to collect stoping analog signals in real time, and converting the stoping analog signals into stoping digital signals; Comparing the amplitude of the stoped digital signal with the original digital signal, comprising: If the amplitude of the stoping digital signal is less than or equal to half of the amplitude of the original digital signal in a plurality of continuous sampling periods, judging that the system is in a working state exceeding a half-amplitude frequency point; If the amplitude of the stoped digital signal is greater than half of the amplitude of the original digital signal in a plurality of continuous sampling periods, the working state of the system in the frequency point which does not exceed half of the amplitude is judged.
3. The method of rapid decay after a half-amplitude frequency bin of an acceleration sensor of claim 2, wherein the number of consecutive plurality of sampling periods is not less than 3.
4. The method of rapid decay after a half-amplitude frequency point of an acceleration sensor of claim 1, wherein rapidly decaying the final analog output signal of the sensor to a zero level comprises: When the system is judged to be in a working state exceeding a half-amplitude frequency point, triggering an attenuation control mechanism to respond, and outputting an attenuation control signal to an attenuation control circuit by a Micro Controller Unit (MCU); and the attenuation control circuit forcibly pulls down the output end of the operational amplification circuit to the reference ground level according to the attenuation control signal, so that the final analog output signal of the sensor is attenuated to the zero level rapidly.
5. The method for rapid attenuation after half-amplitude frequency point of acceleration sensor according to claim 4, wherein the attenuation control circuit comprises an analog switch, the analog switch is driven by a GPIO pin of the micro controller unit MCU, a signal end of the analog switch is connected to an output end of the operational amplifier circuit, and a ground end of the analog switch is connected to a system ground.
6. The method for rapid decay after half-amplitude frequency point of an acceleration sensor according to any one of claims 1-5, further comprising: and when the system is judged to be in a working state exceeding the half-amplitude frequency point continuously in the preset recovery time period, recovering the normal signal output of the sensor.
7. A system for rapid decay after half-amplitude frequency points of an acceleration sensor, comprising: the acceleration sensor chip is used for collecting acceleration and outputting an original digital signal; the SPI communication port of the micro controller unit MCU is connected with the data output end of the acceleration sensing unit and is used for receiving and processing the original digital signal; the input end of the digital-to-analog converter DAC is connected with the digital signal output port of the micro controller unit MCU and is used for converting the processed digital signal into an analog signal; The input end of the analog filter circuit is connected with the output end of the DAC, and the analog filter circuit performs frequency response shaping on the received analog signal and sets half-amplitude frequency points; The input end of the operational amplification circuit is connected with the output end of the analog filter circuit and is used for amplifying the signal amplitude to meet the required voltage value; The sampling end of the attenuation control stoping circuit is connected with a node between the output end of the analog filter circuit and the input end of the operational amplification circuit, and the output end of the attenuation control stoping circuit is connected to an analog-to-digital (AD) input pin of the micro controller unit MCU and is used for collecting analog signals after filtering; And the control end of the attenuation control circuit is connected with the GPIO output pin of the micro controller unit MCU, the signal end of the attenuation control circuit is connected with the output end of the operational amplification circuit, and the grounding end of the attenuation control circuit is connected with the system ground and is used for pulling down the final output signal to 0V under the instruction of the MCU.
8. The system for rapid decay after half-amplitude frequency bin of an acceleration sensor of claim 7 wherein said decay control circuit comprises a single pole double throw analog switch having a control pin connected to a GPIO output pin of said micro-controller unit MCU and a signal terminal connected to an output terminal of said operational amplifier circuit and a ground terminal connected to system ground.
9. The system of claim 7, further comprising an LDO power chip having an input terminal connected to an external DC24V power supply and an output terminal connected to the power pins of the micro-controller unit MCU, the digital-to-analog converter DAC, and the acceleration sensor unit, respectively, for providing a stable operating voltage.
10. The system for rapid decay after half-amplitude frequency bin of an acceleration sensor of claim 7, wherein the analog filter circuit is a second order low pass filter circuit.

Description

Method and system for rapid attenuation of acceleration sensor after half-amplitude frequency point Technical Field The invention belongs to the technical field of signal processing of rail transit sensors, and relates to a method and a system for rapid attenuation after a half-amplitude frequency point of an acceleration sensor. Background The transverse acceleration sensor of the rail train is mainly used for collecting acceleration values of the bogie in the transverse direction (perpendicular to the running direction of the train) in the running process of the train so as to judge whether the transverse acceleration of the train is abnormally increased due to overhigh speed when the train turns around a curve, and further the derailment risk exists. The sensor is a key device of a rail train braking and safety monitoring system. However, there is a certain degree of vibration during the running of the train in actual running. Although the main chip of the acceleration sensor (such as a MEMS chip) has good high-frequency vibration response characteristics, and the output signal is relatively stable in a certain frequency range, the sensor system usually further integrates analog circuits such as circuit devices including DACs, filters, amplifiers and the like. The analog circuit devices are limited by the frequency response characteristics of the analog circuit devices, so that the amplitude of an output signal gradually decays along with the increase of the vibration frequency, and a certain deviation exists between the acceleration value output by the acceleration sensor and the actual value. Particularly, after reaching a certain specific frequency, namely a half-amplitude frequency point (namely, the frequency corresponding to the amplitude of the output signal decayed to half of the vibration-free static output voltage), if the decayed signal is still output in a conventional mode, the signal is very easy to be misjudged as an effective acceleration event by an upper computer, so that false braking or alarm is triggered. At present, the current industry commonly adopts a mode of quickly pulling down the amplitude of an output signal so that the output signal is as output-free as possible to carry out neglect processing so as not to cause misjudgment of a sensor signal acquisition host. However, unlike circuit devices such as a DAC (digital-to-analog converter), filtering and the like, the sensor main chip has better vibration frequency response characteristics, the output of a signal output by the chip is relatively stable under the condition of certain vibration frequency, although the signal is attenuated after being processed by the DAC, the signal is attenuated according to a desired value after being processed by the DAC, the filtering and the like, the attenuation amplitude can only be controlled in a limited way by the traditional scheme of high-order filtering, the expected effect cannot be completely achieved by the slow attenuation process, and if the filtering order is improved uniformly, the output amplitude is possibly oscillated, and the frequency response curve becomes very unsmooth. Therefore, in order to solve the problem, research on solutions from the aspects of hardware and software is urgently needed, and the problems that the high-fidelity output of the main chip of the sensor in the effective frequency band is reserved, the output signal can be actively, rapidly and reliably restrained after the half-amplitude frequency point is exceeded, and misjudgment caused by high-frequency vibration interference is fundamentally solved are realized. Disclosure of Invention In order to solve the technical problem that an output signal of an acceleration sensor cannot be attenuated rapidly at a specific frequency point, particularly after a half-amplitude output frequency point, the invention discloses a method for attenuating rapidly after the half-amplitude frequency point of the acceleration sensor. Specifically, the method comprises the steps of: s1, acquiring an original digital signal output by an acceleration sensor chip, and converting the original digital signal into an analog signal; S2, processing the analog signal through an analog filter circuit with a preset cut-off frequency, so that at the preset cut-off frequency, the voltage amplitude of the analog signal is attenuated to be half of the effective output amplitude in a vibration-free environment, and the preset cut-off frequency is defined as a half-amplitude frequency point; S3, monitoring a stoping analog signal output by the analog filter circuit, converting the stoping analog signal into a stoping digital signal, and judging whether the system is in a working state exceeding a half-amplitude frequency point or not based on an amplitude comparison result of the stoping digital signal and the original digital signal; And S4, when the system is judged to be in a working state exceeding a half-amplitude frequency point, tr