The Study Of Capacitance Method For Precision Displacement And Vibration Measurement

Non-contact capacitance micrometer technology is a new important technique of micro/nanometer measurement, which has developed rapidly in recent years. It has many advantages such as fast dynamic response, good temperature stability, wide measuring range, high precision, small volume, light weight, simple structure, high system natural frequency, etc. So this kind of technology is widely used to measure micro displacements, vibrations, sizes, angle and pressure in the area of aeronautical, astronautical and industry departments.Many research achievements of capacitance micrometer technology have been gained in the static and quasi-static measurements, but it is still in a key stage in the dynamic measurement. For example, dynamic filtering problem, the dynamic frequency response of sensors and measuring circuit is needed to be enhanced, the precision measurement of signal amplitude and waveform display, stability, etc. The purpose of this dissertation is major in studying and achieving dynamic signal measurement on the basis of improving the static and quasi-static measurement accuracy and stability.The principle of capacitance method for precision displacement and vibration measurement is systematically analyzed in the dissertation. The factors of effecting capacitance sensor's output are theoretically analyzed and calculated, and the structure and size of sensor have been optimized and designed. Besides, the dynamic filter for measuring is simulative analyzed and comparative studied. The dynamic filter circuit is also designed and realized which can achieve the measurement of precision displacement and vibration signal between 0 kHz and 3 kHz, and the test results show that it can meet the dynamic testing demands. Based on high-speed USB-based data collection, 10 nanometer resolution of the test system is set up for precision dynamic vibration with capacitance method, and a lot of improvement has done in the circuit on the basis of a large number of experimental studies, thus the stability and reliability of the instrument system is improved.The main sources of errors of the whole testing system are theoretically analyzed in detail, and the non-linear error compensation improves the accuracy of the system using regression analysis method. Finally, some new views are proposed for further study of precision displacement and vibration measurement.