Study On Measuring System Of Differential Transformer Type Displacement Sensor

Since the 1980 s,sensor technology has been attracted large attention,and many countriesand research groups began to study the sensor technology.Among all sensors,differential transformer type sensor has many advantages,such as high accuracy and sensitivity,good linearity,simple but reliable structure,much longer service life,great environmental adaptability and so on,therefore,it is always popular and widely used in our daily life.Our further research and improvement of the traditional differential transformer type sensor is significant,and will certainly create enormous social value.In this paper,we have introduced detailed analysis to the operating principle of differential transformer type sensor,and we built a measurement system of differential transformer type displacement sensor based on AD698 signal conditioner.We have analyzed four key questions of traditional differential transformer type displacement sensor,and improved the output characteristics of the measurement system.Including the following:(1)Zero-residual voltage analysis and its solutionWe have analyzed the causes of zero-residual voltage,and decreased the zero-residual voltage of the differential transformer type sensor by taking advantage of the method of compensating hardware circuit.By compared the zero-residual voltage output waveform before and after the compensation,we found that the fundamental component and the high-order harmonic component of output were effectively compensated.(2)Impact analysis of excitation source frequencyBy the analysis of amplitude-frequency characteristics,we gave a detailed introduction to the effect of exciting sources frequencies on the differential transformer type sensor,and determined the resonance point of the differential transformer type sensor,reduced the influenceof the selection of the excitation source frequency on the output characteristics of the measurement system.(3)Temperature influence analysis and its solutionWe have analyzed the influence of temperature on the measurement system,and achieved temperature compensation of our measurement system by using the support vector machine algorithm.We selected the appropriate parameters of kernel function to make the sensitivity temperature coefficient of our measurement system decreased from /1072.1?)(-2? to/1048.1?)(3-?,which reduced the adverse effect of temperature on the accuracy of the measurement system.(4)Improvement of the non-linearityThrough the calibration test,we selected the working range of differential transformer type sensor with good linearity.Based on curve fitting algorithm,we have achieved the improvement of the non-linearity of our measurement system,making the non-linearity decreased from 1.84%to 0.2%,which largely decreases the non-linear errors of our measurement system.Nowadays,the sensor measurement system is becoming more and more intelligent and networked.In this paper,We added a microprocessor module to the original measurement system,and transplanted the improved algorithm into the MCU.Finally,we achieved the intelligent improvement of the output,and displayed it on LCD.