Research On Micro Ohm Resistance Measurement Based On Digital Cross Correlation Algorithm

With the rapid development of China's economy,transportation,industrial production and infrastructure construction more and more use of metal materials to the equipment.Metal materials working in complex acidic environments are susceptible to corrosion and damage,and bring security risks.In order to avoid the safety accidents caused by it,it is necessary to monitor the corrosion of the metal materials of these devices in real time.There are many ways to monitor the corrosion of metal materials,and it is one of the important methods of material discipline to observe the change of resistance to reflect the corrosion of metal.The current traditional small resistance measuring instrument is generally not suitable for long-term monitoring of corrosion of metal materials in the infrastructure due to the general lack of network function.Therefore,it is of great significance to study a networked instrument with high accuracy,good stability and fast and accurate measurement of small resistance measurement.In this paper,the characteristics of the measurement of the small resistance and the current situation of the measurement method are analyzed.A complete system scheme of extracting the useful signal in the noise by the digital cross correlation algorithm is proposed by using the method of low frequency constant current source and the micro resistance measurement system.This paper discusses in detail the design and overall development of micro resistance measurement system,which is mainly divided into micro resistance measurement theory and algorithm analysis,measurement system hardware design,system software design,system debugging calibration and result error analysis.First,the measurement theory of microresistance includes the measurement of noise,the source of interference and the signal-to-noise ratio of the measurement channel.In this paper,the measurement method of small resistance is analyzed,and the low frequency AC constant current measurement method is selected according to the design requirements of this subject and the characteristics of embedded system design.The measurement scheme and measurement process of low frequency constant current AC measurement method are analyzed in detail.The digital cross correlation algorithm model is used to remove the noise and interference in the useful signal and is analyzed by MATLAB simulation experiment.System hardware design,including the overall design of the hardware system,ARM microprocessor minimum system and peripheral circuit design,high precision D / A AC signal generation circuit design,voltage control constant current source circuit design,16 high precision A / D acquisition circuit design and differential amplifier circuit design,display circuit design,communication circuit design and power circuit design.The software design of the system mainly includes overall design of the software system,the main program design of the software,the dispatching and coordination of the tasks,the D / A conversion program design of the 10 HZ AC signal,the A / D conversion acquisition program Design and algorithmic program design,touch screen and display program design,stall matching program design,communication program design and software reliability program design.System debugging,including hardware debugging,software debugging and the overall system of joint debugging,detailed description of the hardware and software debugging process and debugging methods.A calibration method for measuring the linearity of the test system and measuring its calibration factor is presented.Finally,the correctness of the hardware and software is verified by trial and error.The experimental results show that the system has good linearity in each range of gears.The measurement results and error analysis are given in each range file.The minimum magnitude of the measured range is stable in the micro-European position,which can realize the micro-European resistance measuring.Indicating that the digital cross correlation algorithm in this subject with a small resistance measurement to remove noise and interference to improve the system signal to noise ratio has a significant effect,can accurately measure the micro-European resistance.The design of the small resistance measurement system to achieve the desired goal for the material discipline resistance method to monitor the metal corrosion accurate measurement and analysis laid the foundation.