Structural Simulate Optimization And Signal Transformation Of Cross-capacitance Liquid Level Sensor

The real-time and accurate fuel level measurement has great realistic significance of improving the effective launch capacity of spacecraft.The traditional transducer exist assembly errors and capillarity.Firstly adopt the Principle of Cross Capacitance to modify sensor to lightweight single-tube.This paper is aimed to further optimizing structure and converting signal.The main contents are as follows:(1)Using the finite element method of static electric field,the structure(shield,electrode gap angle,the inner radius of quartz tube,the quartz tube thickness,and the distance between electrode and shield)influence on the sensor sensitivity was analyzed in use of the software ANSYS with single variable principle.Integrated optimization was done combining the orthogonal experiment and statistical analysis.The sensor sensitivity can be increased by 12.6% of the original.(2)On the basis of charge-discharge method,the new capacitance-to-digital converter PCAP01 was used to transform the weak signal by downloading standard firmware,configuring registers and delivering results to PC via SPI communication.The shielding wires with drift connection were to eliminate the electromagnetic interference and noise.Internal and external compensation measurements were also applied to eliminate the parasitic capacitance of wires and chip.(3)Feasibility test of level measurement was conducted on the experimental platform.The results indicate that,during the range of measurement(0~200)mm,the sensor linearity is ±0.8%,the hysteresis error is ±0.1% and the maximum citing error of level measuring is-1.0%FS.The consistency of simulation and test was verified,the sensor sensitivity is 11.1% superior after structure optimization.Signal converter test states that the PCAP01 has more accurate and stable feature,it also enhance the sensor linearity and level measuring characteristic.The research provides a feasible method for optimizing fuel level measurement,and is in favor of application to fuel level measurement in aviation and aerospace.