Study On Machining And Measurement Technology For Electrostatic Suspended Accelerometer Sensor

This thesis concentrates on the machining and measurement technology for electrostatic suspended accelerometers. It mainly discusses the measurement and correction of geometrical errors for hexahedron-like workpieces, such as the accelerometer's electrode cage and plates, aiming to break the bottleneck of ultra-precision machining of accelerometers and meet the demands of the first generation Gravisat. The main aspects of the research and the innovation points are as follows:1. According to the configuration, material characteristics and technical specifications of the sensor, the error-correction-based process is confirmed. After comprehensive analysis of the processing characteristics, a feasible machining and measurement blueprint is proposed.2. A novel method for high precision measurement of geometrical errors is introduced. Not only the value of the error but also the residual error is obtained, which makes the error correction possible for the electrode cage. Then an optical hexahedron with nominal perpendicularity error of 2" is measured and evaluated. The result proves the validity and reliability of the proposed method, achieving high measurement accuracy of 0.5". Moreover, the method can be extended for measurement of the parallelism between inner surfaces of the electrode cage, with the measurement system slightly modified. The perpendicularity error between inner surfaces can also be calculated through certain algorithms. Hence the geometrical errors among surfaces of the electrode cage are figured out.3. The finite element optimal design method and process for ultrasonic lapping and polishing tool are researched. According to the workpiece's characteristics and technical specifications, the ultrasonic tool is designed and the vibration system is built with frequency well matched. The material removal function of ultrasonic polishing is researched through theoretical models and systematic experiments. The influences of parameters on material removal rate and surface quality are analyzed, which offers processing instructions for error correction of the electrode cage.