小型加速度计全数字读出电路设计与研究

发布时间：2018-02-12 16:17

本文关键词： 加速度计全数字闭环 PID控制二元调宽脉冲　出处：《长沙理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：石英挠性加速度计是惯性导航系统组成的关键器件之一,其应用范围涉及航空、航天、航海以及一些民用领域。加速度计的读出精度决定了惯性导航系统的导航精度,传统的加速度计读出电路通过模拟电路实现,模拟电路结构复杂、抗干扰性低缺特点制约了加速度计读出电路的精度和稳定性。随着数字化处理的飞速发展,数字电路逐步具有高稳定性以及高抗干扰性等特性,加速度计的数字化读出成了研究热点,本课题对加速度计的全数字化读出方式进行了研究。通过对传统的模拟读出电路方案和模数结合读出方案的对比与分析,确定了基于FPGA的全数字加速度计读出方案,整个全数字读出电路包含三个模块电路：差动电容检测电路、数字控制电路和力矩器控制电路。采用多方案对比设计,从分辨率、读出精度等角度对比分析了两种差动电容数字检测电路,选用了频率法检测电路实现电容差的检测；采用了数字PID控制算法,实现了加速度计读出电路的闭环自动控制：从加矩功率、分辨率、零偏稳定性、刻度因素及线性度和动态响应等方面对多种PWM数字脉冲力矩器加矩方式进行了对比与分析,确定了二元调宽脉冲的加矩方式实现对加速度计的加矩；设计了FPGA下位机与计算机上位机连接,通过基于VB的可视界面实现了加速度计数据读出的显示、存储以及部分控制,用于对读出电路的测试。对整个加速度计读出电路进行了阶跃、动态、静态等测试,验证了石英挠性加速度计的全数字闭环读出电路的成功实现,可以测得读出电路的读出标准偏差为1.5×10-5g,精度为10-4g的加速度值。
[Abstract]:Quartz flexible accelerometer is one of the key components of inertial navigation system. Its application scope involves aviation, aerospace, navigation and some civil fields. The readout accuracy of accelerometer determines the navigation accuracy of inertial navigation system. The traditional accelerometer readout circuit is realized by analog circuit. The structure of analog circuit is complex and the characteristic of low anti-interference restricts the precision and stability of accelerometer readout circuit. Digital circuits gradually have the characteristics of high stability and high anti-interference. The digital readout of accelerometers has become a research hotspot. The whole digital readout method of accelerometer is studied in this paper. By comparing and analyzing the traditional analog readout circuit scheme and the analog-to-digital readout scheme, the full digital accelerometer readout scheme based on FPGA is determined. The whole digital readout circuit consists of three modules: differential capacitance detection circuit, digital control circuit and torque control circuit. In this paper, two kinds of differential capacitance digital detection circuits are compared and analyzed from the angle of readout precision, frequency method is used to detect capacitance difference, and digital PID control algorithm is used. The closed loop automatic control of accelerometer readout circuit is realized. Several PWM digital pulse torque adding methods are compared and analyzed from the aspects of moment power, resolution, zero bias stability, calibration factor, linearity and dynamic response, etc. The method of adding moment to accelerometer is determined, and the connection between FPGA lower computer and computer is designed, and the display, storage and partial control of accelerometer data are realized by visual interface based on VB. It is used to test the readout circuit. The step, dynamic and static test of the whole accelerometer readout circuit is carried out, which verifies the successful realization of the full digital closed loop readout circuit of the quartz flexible accelerometer. The readout standard deviation of the readout circuit is 1.5 脳 10 ~ (-5) g and the precision is 10 ~ (-4) g.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN96

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