The Design Of The Spring Length Measurement Instrument Based On Mirco-Capacitance

With the rapid development of science, technology and modern industry, there is a greater demand for the fine measuring instrument of higher precision, resolution and stability. Therefore this paper designs a spring length measurement instrument based on the micro-capacitance, which can measure the infinitesimal displacement accurately. Its working principle and the key technology are analyzed systematically.As a non-contact spring length measurement instrument, it has the advantages of higher stability and precision, wider measurement range, greater dynamic response, more simple structure. It can satisfy the demand of modern industry measurement.The capacity transducer translation circuit adopts the variant version of Wheatstone bridge, which two resistances are replaced by a natural capacitance and a variable capacitance. So the capacitance bridge consists of two resistances and the both capacitances. The transducer's cylindrical structure forms the natural capacitance. And the range of the transducer probe and the on-line producing spring form the variable capacitance. The both capacitances with two resistances constitute the capacitance bridge, which measures the change of electrical signal replacing infinitesimal displacement. This transducer structure is simple and the probe installation is very convenient. Combining with subsequent higher precision detection circuit and pc104 control system, this instrument become intellectualized. It not only carries out higher precision and efficiency non-contact measurement, but also can satisfy the demand of dynamic sampling and real-time online detection. Therefore this instrument has a wide application prospect in the modern industry. The main points of this paper are as follows:1) Design and optimize the structure of the sensor to meet the requirements of this measurement system.2) Design a sensor signal detection circuit and define the circuit parameters.3) Optimize the measurement and control system to enhance the stability of the whole system.