The Application Of Adaptive Stochastic Resonance In The Anchor Nondestructive Testing

Anchor bolt has been widely used in large-scale geotechnical engineering,therefore the quality detection of anchor is very important.In the nondestructive detection of anchor,due to the harsh test environment,the sensor data drift and interference caused by the detector itself,the data collected by stress wave reflection method is often submerged in strong noises,which brings great difficulty to damage identification.The weak signal detection of anchor in strong noises has been a hot issue in the field of nondestructive detection.Stochastic resonance is different from conventional denoising method,which uses the noises energy to enhance the weak useful signal buried in noises and makes the weak signal submerged in strong noises reach resonance to greatly improve useful signals.The specific content of this thesis as follows:(1)The classical stochastic resonance is only suitable for detecting small parameter signal(signal frequency,signal amplitude and noises intensity are much less than 1),while the bolt signal collected by stress wave reflection method is the damped oscillation transient signal,which is non-periodic with a large parameter.Aperiodic scale transformation stochastic resonance method can detect aperiodic and large signal.Therefore,aperiodic scale transformation stochastic resonance method is adopted to deal with bolt signal.Based on the advantages of aperiodic stochastic resonance,kurtosis index and correlation coefficient respectively,weighted kurtosis index is used as measurement index.Using scale transformation stochastic resonance method,amplitude is normalized and frequency is linear compressed to meet the requirements of classical stochastic resonance for bolt signal.By dealing with aperiodic large parameter signal,the validity of aperiodic scale transformation stochastic resonance is verified.(2)The parameters of stochastic resonance have a great influence on the resonance effect and the interaction between the parameters directly restricts the resonance effect.Cuckoo search algorithm with simple structure and few control parameters is used to optimize the parameters of stochastic resonance.The cuckoo search algorithm is a new intelligent algorithm for simulating the special breeding method of cuckoo-nest parasitism and Levy ’s flying characteristics.The weighted kurtosis is taken as the measurement parameter,and the optimal parameters a and b are chosen as the stochastic resonance parameters in this thesis.The best stochastic resonance effect can be reached by choosing the optimal parameters of a and b.Finally,the simulation results show that the cuckoo algorithm is superior by simulating the anchor vibration signals.(3)Due to the great important engineering application of stochastic resonance,embedded stochastic resonance bolt nondestructive testing instrument is designed.First,hardware core uses the "DSP+ARM" dual-CPU structure.DSP mainly deals with the stochastic resonance operation and FFT operation.ARM mainly deals with data reading,transmission and display.This type of structure can not only give play to a powerful digital signal processing ability of DSP,but also can give play to a powerful control of ARM.Second,a communication protocol based on SPI is designed to deal with the mass data exchange between ARM and DSP.Data format and SPI interface are defined and design scheme of drivers are given to realize the efficient data transmission.Last,ARM can achieve data acquisition,data transmission and data display.DSP mainly realizes ADC sampling program,stochastic resonance and FFT operation program.Application examples verify the effectiveness of rock bolt nondestructive detection instrument based on embedded stochastic resonance in the detection of weak signal of anchor bolt.