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1、国防科学技术大学 博士学位论文 开环光纤陀螺性能改进及其在光纤矢量水听器姿态测量上的应 用研究 姓名：陈宇中 申请学位级别：博士 专业：光学工程 指导教师：胡永明 2011-04 国防科学技术大学研究生院博士学位论文 第 i 页 摘 要 近年来，智能化水中兵器获得快速发展，由于水下环境的特殊性，惯性导航 和姿态控制，以及基于水声探测的信息系统成为智能化水中兵器的核心关键技术。 本文针对智能化水中兵器应用发展需求，进行开环光纤陀螺性能改进及其在光纤 矢量水听器姿态测量上的应用研究，为智能化水中兵器的运动控制和水声探测技 术发展提供了理论和实验基础。 对水中兵器而言，由于其动态特性和对成本的要求，
2、开环光纤陀螺是比较理 想的惯性器件。本文针对具体结构的开环光纤陀螺，进行了有关改进陀螺性能的 理论和实验研究。通过采用两级波表法，提高了调制信号精度，改善了陀螺工作 点控制稳定性；通过光源相对强度噪声(RIN)抑制方法，在一定程度上抑制了光源 噪声，减小了陀螺随机游走；通过温度补偿，改进了陀螺温度稳定性；通过小波 滤波方法，对陀螺信号中噪声的抑制取得了明显效果。对改进后的陀螺进行了综 合测试，其性能明显优于国外在我国市场大量销售的开环光纤陀螺。 光纤矢量水听器的测量是相对其自身载体坐标系的测量。在运动平台上，光 纤矢量水听器上变化的载体坐标系下测量的结果需变换到统一的参考坐标系下。 本文结合矢
3、量水声信号处理的特殊要求，进行了动基座下矢量水听器目标定向、 四分量信号融合和水声场求解所涉及的姿态变换算法研究。针对光纤陀螺角速度 输出的特点，推导了基于角速度测量的姿态算法，在典型的圆锥运动和划桨运动 条件下，对改进的算法进行了优化，仿真结果表明，优化后的算法误差更小。 分析了光纤矢量水听器姿态测量系统的误差，针对矢量水听器应用的特点对 误差方程进行了简化，分析了静基座下误差传播特性，得到了误差振荡频率。分 析了姿态测量误差对矢量水听器目标定向误差的影响，针对无声学噪声及有声学 噪声两种不同情况，推导了定向误差随姿态误差变化的关系式，对有噪声的情况 进行了仿真，仿真结果证明推导的关系式正确
4、。 研究了光纤矢量水听器姿态测量系统的标定与初始对准方法。标定需做位置 试验及转动试验，可标定出光纤陀螺、加速度计、磁罗盘的零偏、标度因数和安 装误差这些参数。由于开环光纤陀螺是中等精度的陀螺，因此初始对准不能通过 陀螺来进行，而需引入磁罗盘。初始对准分为粗对准和精对准两个阶段，分析了 粗对准的精度，精对准使用磁罗盘辅助的卡尔曼滤波方法，分析了卡尔曼滤波的 可观测度，进行了计算机仿真，仿真结果表明引入磁罗盘可提高对准精度，方位 角误差由 4降低至 10。 设计并研制了一套基于开环光纤陀螺的光纤矢量水听器姿态测量系统，其中 包括硬件及软件的设计与调试。对姿态测量系统进行了全面的测试，包括静态测
5、国防科学技术大学研究生院博士学位论文 第 ii 页 试、转动测试，并与光纤矢量水听器进行了联合海试，海试结果表明，光纤矢量 水听器用姿态测量系统所测得的姿态进行姿态变换后，目标定向的精度有较大幅 度的提高，方位角标准差由 67降至 23。 论文的主要研究成果和创新性如下： (1) 提出采用两级波表法可产生开环光纤陀螺的高精度调制信号；提出了一种 RIN 抑制方法，可在一定程度上抑制开环光纤陀螺的光源噪声。 (2) 针对光纤陀螺角速度输出特点，对等效旋转矢量算法及划桨效应补偿算法 进行了优化，使算法误差更小。 (3) 分析了姿态测量误差对光纤矢量水听器目标定向误差的影响，对无声学噪 声情况，给出
6、了方位角、俯仰角误差随姿态误差变化关系式，对有声学噪 声情况，给出了方位角、俯仰角平均值及方差随姿态误差变化关系式。不 论哪种情况，当目标俯仰角较大时，小的姿态误差都会导致姿态变换后大 的方位角定向误差，提出应用时应尽量减小目标俯仰角。 (4) 设计并研制了一套基于开环光纤陀螺的光纤矢量水听器姿态测量系统，其 中三轴光纤陀螺模块采用了一体化的电子学处理方式，从而降低了体积与 成本，并使三轴陀螺的时钟完全同步。该套姿态系统在水下可正常工作， 光纤矢量水听器姿态变换后目标定向的结果正确。本文将开环光纤陀螺应 用于光纤矢量水听器的姿态测量，这在国内尚属首次。本文的工作是一次 真正意义上的光纤陀螺水中
7、工程应用。 关键词：开环光纤陀螺；光纤矢量水听器；姿态测量；目标定向；误差分析； 国防科学技术大学研究生院博士学位论文 第 iii 页 Abstract In recent years, intellectualized underwater weapons are developing rapidly. Due to the particularity of underwater environment, inertial navigation, attitude control and acoustic detection have become key technologies of u
8、nderwater weapons. To fulfill applying and developing requirement of underwater weapons, performance improvement of open- loop fiber optic gyroscope(FOG) and its application in attitude measurement for fiber- optic vector hydrophone were studied. These researches provide theoretical and experimental
9、 basis for the underwater weapons technical development of motion control and acoustic detection. To underwater weapons, because of its dynamic characteristic and requirement of low cost, open- loop FOG is an ideal inertial component. To specific structure of open- loop FOG, theoretical and experime
10、ntal researches on gyro performance improvemen were investigated. The accuracy of modulation signal was improved by two- level wave table method, and also was the control precision of work point. Relative intensity noise(RIN) of source was suppressed to a certain extent by a new RIN subtraction algo
11、rithm, and the random walk was decreased. Temperature stability of the gyro was improved by temperature compensation. Noise on gyro signal was obviously suppressed by the wavelet de- noise method. The improved gyro was tested, and the result shows the performance of the gyro is obviously better than
12、 the imported open- loop FOG selled in our market. The measurement of fiber- optic vector hydrophone is based on body frame of itself. In a movement platform, measurement results with respect to changing body frame of fiber- optic vector hydrophone should be transformed to same reference frame. Due
13、to particular requirement of vector acoustic signal processing, attitude transform algorithm for direction of arrival (DOA) estimation, signal fusion of four components and acoustic field calculation were studied. Due to FOGs characteristic of angular velocity output, attitude algorithms based on an
14、gular velocity measurement was deduced. Improved attitude algorithms were optimized under classical coning motion and sculling motion. The simulation result shows optimized algorithms have lower error. The error of attitude system was analysed, and the error equations were simplified under applying
15、property of vector hydrophone. Error propagation equations on fixed platform were analysed, and error oscillation frequencies were gotton. Influence of attitude measurement error to DOA error was analysed, and its formulas were derived without and with acoustics noise. The formulas were proved corre
16、ct by simulation result. Methods of calibration and initial alignment were studied. Position trial and rotation trial were needed when calibrating. FOG, accelerometer and compasss 国防科学技术大学研究生院博士学位论文 第 iv 页 parameters of bias, scale factor and installation error can be calibrated. Because open- loop FOG is a kind of middle grade gyro in precision, initial alignment can not be accomplished only by FOG, magnetic compass was needed. Initial alignment was divided into two stage of coarse
