Development Of A Differential Capacitive Displacement Sensor Calibration Platform With Guard-ring

As a traditional transducer of non-contact measuring system, capacitance transducerhas a lot of advantages such as simple structure, fast response rate, high accuracy, thecapability of dynamic test, etc. Capacitance transducers can be used to measuredisplacement, angle, oscillation, acceleration, pressure and moisture, etc.Therefore, thecapacitance transducer is widely used in the field of geophysics, aeronautics, high-techelectronics and industrial applications so on.Precision electrostatic accelerometer or space inertial sensorshas very importantapplications in satellite gravity measurements, space-based space science experiments suchas the equivalence principle testing and gravitational wave detection, and high-accuracydifferential capacitive displacement sensor is one of the key technologies of spaceelectrostatic accelerometer or the sensor, so that its performance indicators, such as theresolution will be more better. Sensitivity coefficientis critical for capacitive displacementsensor or accelerometer inertial sensors’ closed-loop system design and simulationparameters, and it is also required in measuring capacitive displacement sensor resolution,so how to high precisionlycalibrate thecapacitive displacement sensor sensitivity is veryimportant, high-precision calibration platform is very worthy of study.It need to make a the stability differential capacitor tocalibrating capacitivedisplacement sensor sensitivity coefficients. If using the traditional parallel plate capacitorto constitute differential capacitance, the actual values of capacitance nonlinearity errorbecause of theedge effects, thereby calibrate the sensitivity coefficient error is very large,the difference can be up to40%~50%with the theoretical value, in order to reducethenonlinear impact of the calibration platform and reduce the calibration error, we need toadopt some of the impact of technology shielding edge effects.Currently,the commonmethod indomestic and international is to add guardring to shield equipotential edgeeffects. The main goal of this research is to develop a high-precision calibration platform, firstly how to shield the edge of a parallel plate capacitor with the guard ring is analyzed intheory.Secondly, make a stable standard differential capacitance (using guard ringtechnology) design, fabrication and testing according to the theoretical analysis, combinewith high-precision differential capacitive displacement sensor to complet its sensitivitycalibration, calibration error indicators meet the needs and consistent with the theoreticalanalysis. The result show that the developed high-precision capacitive displacement sensorcalibration platform to meet the requirements of sensitivity calibration.