球、柱面变间隙电容传感器的精密测量研究

Research on Cylindrical or Global Capacitance Sensor for Dynamic Gap Measurement

本文对球、柱面间隙电容传感器进行了分类，定义了几个重要参数，将误差分为电路和机械的，并完成了理论与实验研究。文章以精密的静电陀螺为例，研制了转子位移电容分辨率标定装置，使陀螺转子相对位移分辨率、零点稳定度可标定到０．

In the paper some dynamic precision measurement items are dealt with about cylindrical or global capacitance sensors. The main scopes are included in the follows:1. Classification of cylindrical or global capacitance sensors for dynamic gap measurement:static or dynamic, absolute or relative measurement,in which the most valuable one is dynamicrelative one,and high sensitivity for gap measurement will lead high sensitivity for noises coming from mechanical or electrical elements.2. Definition of several important parameters based on mechanical and electrical factors:linear measurement range of dynamic gap △δm,mechanical miscentering △δ1,electrical sensitivity range Vm,electrical sensitivity threshold V01, and general sensitivity K,for which all the exchangeable relationships have been set up. Based on the above, the error band caused by mechanism or electricity is introduced respectivelly, and as a result the error rhombus has been combined,with which all reasons and mechanism for errors have been explained theoritically.3. Determination of the electrical errors and their sources of cylindrical or global capacitance sensors for dynamic gap measurement. The treatments for the errors have been exactly proposed.4. Linking relationship between mechanical errors and geometrical center,gravity center, rotating center of the measured rotor. Comparing with geometrical center of the rotor,the miscentering of its gravity center can be divided into two parts: branch of rotating axle ez,branch of radial direction er. Here the ez is harmful; and the er can be used to measure rotating ratio,direction and radial of the rotor. Especially the er has been used to uniform the rotor rotating speed with electrical field. Also the formula have been deduced to calculate distances or values of mass miscentering in axle and radial directions.5. As a real example the rotor microdisplacement of ESG (Electrostatically Suspended Gyro)is shown in the paper. In order to calibrate the accuracy of the measurement circuit of rotor displacement,a test apparatus for measuring the capacitance resolution of measurement circuit has been developed firstly by the author. As shown by the calibration results,the capacitance resolution and unstability of the circuit is ≤ 0. 012pF,which is equivalent to the displacement of rotor 0. 01μm.