Research On Improving The Measurement Accuracy Of Resistance Based On The Shaped-function Signal

The value of resistance is a basic electrical parameter in electrical and electronic engineering areas,so obtaining accurate resistance measurement values is helpful to improve the performance of the whole system fundamentally.With the development of modern science and technology and advances of electronic industry,more and more sensors are applied to industrial manufacture,medical instrument,safety control,environmental monitoring and other fields.A large part of them are resistive sensors,and the corresponding parameter values can be obtained accurately and indirectly when resistance values are accurately achieved.For example,the pressure sensitive sensor performance as the form of resistance,and accurate measurement of resistance can get accurate pressure value;the different resistance values of linear potentiometer also can reflect the different location.So it is of great importance to realize accurate measurement of resistance values.This paper presents a novel method that exploits shaped function excitation signal and oversampling technology to improve the measurement accuracy of resistance.From the point of changing the excitation signal,this method achieves the purpose of improving the measurement accuracy significantly without increasing the cost and complexity of the measurement circuit system compared with the traditional constant amplitude signal method.The whole measurement system is simple,fast,low cost and high precision.Based on the idea of voltmeter-ammeter method,this paper studies and explores the new method to improve the measurement accuracy of resistance and completes the following works:Firstly,this paper introduces the method of improving the measurement accuracy of resistance and the key technologies involved,including the shaped-function signal,oversampling and so on,and analyzes the feasibility of the application of sawtooth shaped-function signal and oversampling technology to resistance measurement in this paper.And the theory principle of improving the accuracy and signal to noise ratio of the measurement system using sawtooth-shaped-function excitation signal and oversampling is studied.Then a comparison of the measurement accuracy between the new method and traditional constant amplitude signal method is made to verify the efficiency and superiority of the proposed method theoretically.Then,a complete set of resistance measurement system is designed to verify the effectiveness of the proposed method.The whole measuring system is divided into three modules: the first part is to generate sawtooth-shaped-function excitation signal based on the data acquisition card,which is used to drive the conventional resistances;the second part is the data acquisition module,in which the data acquisition card is used to accomplish the oversampling and down-sampling progresses and convert the analog signals into digital quantities;the third part is the host computer processing module,which sents the collected data to the computer for processing and analysis.Lastly,experiments are carried out to validate the proposed method,including the simulation experiment in MATLAB and the designed resistance measurement system experiment.So the feasibility and effectiveness of the new method for improving the measurement accuracy of resistance is demonstrated in this paper.Finally,the accuracy and error of the measurement results are analyzed qualitatively and quantitatively.Meanwhile,the accuracy evaluation standard is used to evaluate the accuracy of measurement.