Design of Micro Displacement Measurement System Based on Flat Capacitive Sensor

In the field of aerospace remote sensing, the precision requirement for beam pointing adjustment mechanisms, fast reflectors and other devices have reached the nanometer level. Traditional photoelectric encoders and inductosyns cannot meet the measurement requirements. Capacitive sensor detection technology has the advantages of low power consumption, high accuracy, good dynamic performance, non-contact measurement. So it is very suitable for use in the field of micro displacement measurement. This paper first introduces the principle and measurement methods for the flat capacitive sensors. Then, based on the AC excitation measurement method, the design of measurement system is introduced in detail. Finally, an experiment system is built to test the linearity, accuracy and stability of the detection system. The experiment results show that within range of ± 2.5mrad, the displacement measurement system can reach the stability of ±0.2μrad, measurement accuracy of ± 1μrad and the linearity is 0.062%.