基于静电悬浮的扭秤式重力梯度仪关键技术研究

发布时间：2018-02-03 19:41

本文关键词： 重力梯度仪水平扭秤静电悬浮　出处：《清华大学》2016年博士论文　论文类型：学位论文

【摘要】：重力梯度测量在大地测量、地质勘探、辅助导航等诸多领域都有着极其重要的应用。为了研究高精度的重力梯度测量技术,设计了一种基于静电悬浮的扭秤式重力梯度仪方案,利用静电悬浮克服扭秤的重力,实现扭转轴沿水平方向的水平扭秤,可以检测重力垂直梯度Гzz产生的作用力矩。改变扭秤的方位,通过多个力矩平衡方程的解算,可以测量出包括重力垂直梯度Гzz在内的全部梯度张量。完成了静电悬浮相关的电路设计,包括差动电容检测电路和高压放大电路。差动电容检测电路的灵敏度为324.6 mV/pF,分辨率为0.47 fF,-3dB带宽约为26.8kHz,针对实验系统中的电极结构,其相应的位移检测分辨率为1.6 nm。高压放大电路的输出范围为0~850V,直流放大倍数约为100倍,交流输出的峰峰值为30V时,电路的失真频率为1.9 kHz,带宽满足实验系统的需求。为了研究水平扭秤的基本特性,搭建了基于平板电极静电悬浮的水平扭秤系统。通过调节8个支承电极的调控电压,在z、x?、y?等三个自由度上实现了对扭秤的静电反馈控制,其悬浮质量可以达到10 g。在零位附近,系统在三个自由度上的运动可以实现解耦,单个自由度的闭环频率特性近似为二阶系统。测试了水平扭秤闭环力矩检测的灵敏度,力矩检测灵敏度约为1.30×105 V/Nm。分析了平板电极结构中,扭秤闭环力矩检测的制约因素,并对水平扭秤的悬浮支承和扭转检测之间的耦合问题进行了讨论。为了克服水平扭秤中悬浮支承与扭转检测之间的耦合问题,提出了基于圆筒电极的悬浮控制方案,并对基于圆筒电极静电悬浮的扭秤式重力梯度仪进行了具体的设计。分析了圆筒电极的电容分布与静电力受力情况,建立了圆筒电极的静电悬浮控制模型。系统的重力梯度分辨率取决于扭转电极的力矩检测灵敏度。利用竖直扭秤对高灵敏度的闭环力矩检测进行了实验验证,其灵敏度可以达到6.97×109 V/Nm。在该灵敏度条件下,当检测信号的分辨率为0.1 mV时,相应的重力梯度分辨率可达1.9 E,有望实现高精度的重力梯度测量。
[Abstract]:Gravity gradient surveying is very important in many fields such as geodesy, geological exploration, auxiliary navigation and so on. A kind of gravity gradiometer based on electrostatic suspension is designed in this paper. Using electrostatic suspension to overcome the gravity of torsion scale, the horizontal torsion scale along the horizontal direction of torsion axis is realized. The torque produced by vertical gravity gradient can be detected, and the direction of torsion balance can be changed, and the solution of multiple moment balance equations can be obtained. All gradient Zhang Liang including gravity vertical gradient can be measured. The circuit design related to electrostatic levitation has been completed. The sensitivity of the differential capacitance detection circuit is 324.6 MV / PF and the resolution is 0.47fF. The bandwidth of -3dB is about 26.8kHz. For the electrode structure of the experimental system, the corresponding displacement detection resolution is 1.6 nm. The output range of the high-voltage amplifier circuit is 0 ~ 850V. When the DC magnification is about 100 times and the peak value of AC output is 30V, the distortion frequency of the circuit is 1.9 kHz, and the bandwidth meets the requirements of the experimental system. A horizontal torsion scale system based on electrostatic suspension of flat electrode is built. ,y? The electrostatic feedback control of the torsion scale is realized on three degrees of freedom, and the suspension mass can reach 10 g. In the vicinity of zero position, the motion of the system on the three degrees of freedom can be decoupled. The closed-loop frequency characteristic of a single degree of freedom is approximately a second-order system, and the sensitivity of the closed-loop torque detection of the horizontal torsion scale is tested. The sensitivity of torque detection is about 1.30 脳 105V / Nm. The restrictive factors of torsion scale closed-loop torque detection in plate electrode structure are analyzed. In order to overcome the coupling problem between suspension support and torsion detection in horizontal torsion scale, the coupling problem between suspension support and torsion detection is discussed. The suspension control scheme based on cylinder electrode is put forward, and the torsion scale gravity gradiometer based on electrostatic suspension of cylinder electrode is designed in detail. The capacitance distribution and static electric force of cylinder electrode are analyzed. The electrostatic suspension control model of cylinder electrode is established. The gravity gradient resolution of the system depends on the torque detection sensitivity of the torsion electrode. The high sensitivity closed-loop torque detection is verified by using vertical torsion scale. The sensitivity can reach 6.97 脳 109V / Nm. Under this condition, when the resolution of the detection signal is 0.1 MV, the corresponding gravity gradient resolution can reach 1.9 E. It is expected that high precision gravity gradient measurement will be realized.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O314

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