Design And Implementation Of Multi-Channel Resistance Strain Acquisition System

In industrial production,strain is a very important parameter.For example,the multipoint accurate measurement of strain plays very critical role in the fields of wind tunnel testing,missile structural testing,vehicle structural strength etc.In measurement scenarios,it is necessary to meet the requirements of high precision,multi-channel and convenient networking at the same time.In order to meet the needs of strain measurement,this thesis designs a multi-channel,high-precision and convenient networking resistance strain acquisition system by improving the excitation power and ADC acquisition circuit,using DMA and dynamic window mean filtering.(1)In order to adapt to various application scenarios of resistive strain sensor connection,a circuit design scheme using high-precision reference voltage and digital-toanalog converter is designed.The influence of the excitation source output accuracy on the measurement error was analyzed,and the theoretical excitation source output accuracy was deduced.The variable voltage output in the range of 2.5V?10V with 0.01%precision of the excitation source is realized.(2)In order to reduce the influence of channel acquisition error and excitation voltage noise on acquisition,the program-controlled bridge,signal conditioning and selfadjusting dynamic feedback measurement circuit are designed in this thesis.The program-controlled bridge can choose 1/4 bridge,half bridge and full bridge connection to reduce the impact of the environment on the measurement.In the 1/4 bridge mode,the three-wire bridge connection method can be set to reduce long-term errors.Signal conditioning uses a signal path with program-controlled three op amps and three-stage differential low-pass filtering to achieve signal conditioning.The measurement circuit adjusts the digital potentiometer through the bisection method,and feeds back the excitation voltage ratio to the reference voltage of the ADC,reducing the error caused by the excitation voltage to the measurement.(3)In order to balance the contradiction between the system data fluctuation processing capability and the response rate.This thesis designs a dynamic window mean filtering algorithm,which adjusts the filter window size through the sampling value to improve the balance between the sampling data fluctuation and the response speed.This thesis designs a dual DMA self-circulation data processing to solve the problem of data collision and data loss data loss during ARM multi-serial communication.The dual DMA self-circulating data processing caches serial data through dual DMA,uses cyclic array to store data,and performs data processing in ARM idle time to improve the utilization efficiency of the microprocessor.The test platform and scheme were designed based on the system in this thesis,and it separately conducted tests on the functions and indicators of the system.The multichannel resistance strain acquisition system designed in this thesis can be connected to multiple machines through Ethernet to realize convenient networking,and can be flexibly combined according to the number of channels required.The strain measurement in the range of-20000 ?? ?20000 ?? is realized,and the measurement accuracy can reach0.1%,which meets the requirements of the overall design index.Based on the test results,the multi-channel resistance strain acquisition system designed in this thesis can meet the strain measurement requirements of multi-point and high-precision.