A safety monitoring method for embankments based on adaptive feedback vibrating wire sensors

Abstract

The invention discloses a dam safety monitoring method based on an adaptive feedback vibrating wire sensor. The initial resonance frequency is used as the initial excitation frequency, and the total number of pulses Nf required for the minimum vibration of the steel string is used to adaptively adjust the excitation time; the interrupt counter of the STM32 processor and the double-trigger method of the timeout timer are used to determine the end of the vibration pickup. The pickup time is counted, and the pickup frequency is calculated according to the equal-precision frequency measurement method; the concept of frequency difference state Sf is introduced, the difference between the pickup frequency and the excitation frequency is calculated, and the state of Sf is determined. When Sf is in an ideal state, the vibration pickup frequency is the resonant frequency; when Sf is in a non-ideal state, update the excitation frequency according to f=f±fdeta, and re-excite the vibration. The invention reduces the single excitation time and improves the efficiency of dam safety monitoring; adopts a feedback-based frequency sweep method to realize equal-precision self-adaptive adjustment, and shortens the time for dam safety monitoring.

Description

[0001] Technical field: [0002] The invention belongs to the field of vibrating wire sensor monitoring, in particular to a dam safety monitoring method based on an adaptive feedback type vibrating wire sensor. [0003] Background technique: [0004] The vibrating wire sensor has the characteristics of simple structure, good stability and high detection accuracy, and the output signal of the vibrating wire sensor is a frequency signal. Because the frequency signal can be transmitted over a long distance, the vibrating wire sensor can be applied to long-distance detection field. Therefore, vibrating wire sensors are widely used in engineering safety detection of dams, bridges, subways, coal mines, and foundation pits. [0005] The vibration method used for vibrating wire sensor monitoring is generally divided into two types: high-voltage plucked string excitation and low-voltage sweep frequency excitation, but these two excitation methods have relatively large limitations. The...

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Problems solved by technology

The limitations of these two excitation methods are as follows: high-voltage plucked string excitation, short steel string vibration duration, difficult to pick up the signal, poor measurement accuracy, and high voltage is easy to accelerate the aging of the steel string and cause the sensor to fail; Although the frequency excitation method uses low-voltage excitation to protect the steel strings, the frequency sweep signal is a continuous pulse signal from the lower frequency limit to the upper frequency limit. In order to ensure the excitation effect, the pulse of each frequency must last for several cycles. Excitation time is too long

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