The Design Of Strain Micrometer Sensor’s Measurement System

With the development of science and technology in the manufacturing industry, therequirements for precision and quality of the product are increasingly high, which leadsto a more rigorous request to precision testing machines. The currently used instrumentsfor small displacement precision measurement primarily are inductance sensor,micrometer, torsional spring table, pneumatic measuring instrument, capacitance digitaldisplay meter, raster measuring instrument, capacitance micrometer. The inductancecomparator’s accuracy is very high up to1/10micron, however it is too expensive topopularize. Micrometer and torsional spring table are the most popular precision testingmachines. They are proved to be stable in performance, low in price after years ofdevelopment, but their precisions are more than ten micron, and they cannot bedigitalized. Pneumatic measuring instrument, capacitance digital display meter, rastermeasuring instrument, and capacitance micrometer are some small displacementmeasurement instrument developed in recent years. They are of low accuracy in thecomputer interface circuit, besides the measurement range of capacitance micrometer issmall.Through thorough investigation and theoretical analysis, in this paper by imitatingthe technology of the electronic scale, we tried to develop a small displacementcomparative-strain sensing precision measuring instrument. The specific work is asfollows:①Basic theory learning and research of the strain sensing precision measuringinstrument: introducing the idea of developing strain measuring instrument and theworking principle of strain measuring instrument, then according to the applicationconditions and working principles design the structure of a strain measuring sensor.②Designing the structure of a strain measuring sensor: based on measuringrequirement of a strain measuring sensor and the designing principle of sensor elastomer,the elastomer uses the integrity design, which can effectively eliminate the error broughtby combination structure; according to the calculation method of mechanics of materials,based on the scale of measuring force we calculated the sensor size.③Conditioning circuit design: according to the characteristics of strain measuringsensor, the sensor signal should be processed by amplification, filtering, A/D conversion,data acquisition and displaying the output control, etc. The conditioning circuit and the controlling process of the controlling system were designed.④Electric bridge way choice: according to the structure of elastomer and the typeof strain gauge, a strain measuring sensor paste four single bridge strain gage on bothsides of the elastomer, using full bridge way, so as to increase the output voltage and toimprove the sensitivity of the bridge, therefore realizing the temperature compensation,eliminating the influence of non-measurement load, showing us the pasting craft ofstrain gauge.⑤The designing and debugging of static calibration experiment platform:introduce the work principle of the static calibration experiment platform strainmeasuring instrument, in order to reduce the experimental error, the traditional methodof bearing is replaced by the spring at the pivot point; test the input and output of aknown range weighing sensor; validate the feasibility of a strain measuring sensordevelopment; debug and improve the control system.⑥The static calibration experiment: to test the input and output of a strainmeasuring sensor, evaluate its static characteristics, and then write the control processchart, and finally determine the corresponding variable of a strain measuring sensor.