基于SERF原子磁强计的三轴磁场顺序补偿方法研究

无自旋交换弛豫(SERF)原子磁强计是一种灵敏度非常高的磁强计,而剩余磁场强度是影响SERF原子磁强计灵敏度的主要因素之一。为此,提出了一种SERF原子磁强计三轴磁场顺序补偿方法,该方法将剩磁范围分为三个部分,每个部分对应不同的补偿方式,并且使用软件对顺序补偿的整个过程进行了仿真实验。实验表明,该方法可以不受补偿前原始剩磁大小的影响,更具有普适性。     

无人机磁惯导系统中航向校正的双内积算法

针对无人机磁惯导系统中广泛采用的三轴磁强计,建立航向角误差模型,分析出航向角的非对准误差等效为常值误差加半圆罗差,提出了一种基于双内积的航向误差校正方法,即利用地磁场矢量与自身内积得到的模值为定值以及地磁矢量与重力矢量二者的内积为常数原理进行航向角解算补偿。该方法能克服基于矢量模值不变校正方法无法补偿非对准误差的缺陷,可实现三轴磁强计的完全校正。数值仿真及实验结果显示,该方法校正效果优于标量校正法、点积不变法以及两步法,能有效降低磁场矢量的模值误差和无人机航向角误差,且对磁惯导系统中的传感器噪声有较好的鲁棒性。     

无自旋交换弛豫原子磁强计的主动磁补偿

由于外界磁场扰动会降低无自旋交换弛豫(SERF)原子磁强计的磁场测量灵敏度,本文根据SERF原子磁强计的测量原理,提出了一种基于原位磁测补偿外部磁场扰动的方法。该方法通过调制解调的方法对3个方向的磁场进行解耦,实现3个方向磁场信息的独立测量。然后,将3个方向磁场的测量信息作为反馈,调节电流源输出给线圈的电流,使线圈产生一个与外界扰动磁场大小相同方向相反的补偿磁场。最后,在现有的SERF原子磁强计实验平台上搭建了主动磁补偿系统,实现了对外部扰动磁场的补偿。与手动补偿方式相比,本文提出的主动磁补偿方法可将剩余磁场的平均值从0.317 8nT降低到0.040 4nT,同时将剩余磁场的均方差由0.348 1nT降低到0.024 7nT。得到的实验结果验证了本文所述方法的有效性。     

基于高斯牛顿迭代算法的三轴磁强计校正

三轴磁强计存在各轴刻度因子、零偏和轴间非正交性误差,需要研究其校正方法。基于标量校正法思想,对磁强计校正模型进行了推导,提出基于高斯牛顿迭代法的磁强计校正方法。采用高精度质子磁力仪提供磁场基准值。借助无磁转台转动磁强计,转动过程中磁强计连续采样,测量数据更具代表性和实用性。仿真结果表明,磁强计误差从162.135 nT降低到1.467 nT。实验结果表明,校正后,磁强计绕3个轴转动的测量值误差分别从1133.887 nT、1317.554 nT、1303.994 nT降低到36.964 nT、20.922 nT、15.664 nT。表明该方法能有效降低磁强计测量误差,磁强计精度明显得到提高。     

基于有限脉冲响应模型的飞机磁场补偿方法

通过分析飞机磁场数学模型,将飞机磁场表示成方向余弦与其乘积项的函数.鉴于模型参数之间存在很强的复共线性,提出了基于有限脉冲响应模型飞机磁场补偿方法.该方法将光泵磁强计和三轴磁强计的输出作为有限脉冲响应模型的输入,由带通滤波器提取信号中的变化成分,再用最小方差估计有限脉冲响应模型参数,并利用有限脉冲响应模型参数计算飞机磁场.从测量总磁场中减去飞机磁场,可得到目标信号磁场数据.最后,通过计算机仿真验证了该磁场补偿方法的有效性.     

SERF原子磁强计自适应参数标定方法研究

由于串扰、AC-Stark效应等因素的影响,导致SERF原子磁强计的空间位置(三维坐标以及灵敏轴指向)以及增益系数发生偏差,直接影响磁源定位的精度。针对以上问题,提出了一种自适应的SERF原子磁强计参数标定方法。基于磁偶极子模型设计了标定装置,装置由24个精密加工的圆线圈组成,用来施加标定磁源。提出了一种改进的自适应精英遗传算法,以同时标定磁强计的相关参数。实验结果表明,算法拟合得到的实际磁场曲线和理论磁场曲线之间的平均相关系数为99.55%,x轴坐标值漂移最明显,平均绝对偏差为2.63 mm,灵敏轴的平均绝对偏差为8.21°,这意味着在磁源定位前,需要对传感器参数进行准确测量。提出的标定方法对于提高磁源定位精度具有一定的参考意义。     

基于无迹卡尔曼滤波和设备的三轴磁强计校正

采用无迹卡尔曼滤波(unscented Kalman filter,UKF)磁强计模型参数估计方法,提出对三轴磁强计的总量及分量误差进行校正。采用高精度质子磁力仪提供磁场基准值,借助无磁转台实现磁强计全方位转动,对一款DM-050三轴磁强计进行了参数估计,并将参数估计值运用到总量和分量校正。仿真结果表明,参数估计值与磁强计实际参数值一致。校正后,磁强计总量误差从427.9 nT减少到2.06 nT;X、Y、Z轴分量误差分别减少到1.84 nT、1.96 nT、1.72 nT。而且证明了UKF对磁强计模型参数估计的重复性良好,并研究了噪声幅度大小对UKF的性能影响程度。实验结果表明,磁强计误差从114.94 nT减少到14.47 nT,表明该方法能有效提高磁强计测量精度。     

三轴磁强计转向差的自适应校正

三轴磁通门磁强计被广泛地应用于地磁和空间磁场的研究。利用三轴磁强计的输出向量来估计被测磁场的模量,会有转向差存在。转向差是由磁强计三个磁轴的非正交性、各通道定标比例系数的不一致性以及各通道的零点偏置引起的。要精确计算被测磁场的模,校正转向差,就必须估计出磁强计的上述参数。本文提出的校正方法对磁强计的参数进行估计,不需造价昂贵的专用设备。仿真试验及实测数据证明这些方法是行之有效的。     

斜端面Hopkinson杆校准多维高g值加速度计方法研究

为了对多维高g值加速度计灵敏度系数进行校准,提出一种斜端面Hopkinson杆实现多维加速度计量脉冲方法。首先,通过ANSYS/LS?DYNA有限元软件分析了斜面角度和激励脉宽对斜面上质点波形的影响,定义杆端斜面部分沿杆轴向投影L与激励脉冲波长λ的比值为δ;其次,利用改进的斜端面Hopkinson杆对三轴加速度计中2个轴的灵敏度及交叉灵敏度系数进行同步校准,得到不同气压下灵敏度系数矩阵。研究结果表明：δ并不是决定斜面质点加速度波形的唯一参数,但对相同L的校准杆,δ值越小,斜面各质点加速度波形越趋于一致;因轴间耦合作用,双轴同步校准得到的各主轴灵敏度系数要小于单轴依次校准,且z轴方向激励（安装面法线方向）对y向（安装面切向）输出影响较大。     

分子法拉第磁光效应磁强计原理研究

基于NO2气体分子的法拉第磁光效应，采用磁旋转光谱技术，理论分析并实验测量了磁光信号对直流磁场的线性依赖关系。结合早先的磁光信号与交流磁场的线性关系，阐述了一种新型分子法拉第磁光效应磁强计的原理，预期其可以对5μT-100mT、DC-1MHz的范围内的磁场进行相对测量。     

Integrated calibration and magnetic disturbance compensation of three-axis magnetometers

Technological limitations in sensor manufacturing and unwanted magnetic fields will corrupt the measurements of three-axis magnetometers. An experiment with four different magnetic disturbance situations is designed, and the influence of hard-iron and soft-iron material is analyzed. The calibration method with magnetic disturbance parameters is proposed for calibration and magnetic disturbance compensation of three axis magnetometers. It is not necessary to compute pseudo-linear parameters, thus the integrated parameters are computed directly by solving nonlinear equations. To employ this method, a nonmagnetic rotation equipment, a CZM-3 proton magnetometer, a DM-050 three-axis magnetometer, two magnets and two steel tubes are used. Calibration performance is discussed in the four situations. Compared with several traditional calibration methods, experiment results show that the proposed method has better integrated compensation performance in all situations, and error is reduced by several orders of magnitude. After compensation, RMS error is reduced from 10797.962 nT to 15.309 nT when the big magnet and steel tube are deployed. It suggests an useful method for calibration and magnetic disturbance compensation of three-axis magnetometers.     

十字形磁梯度张量系统的误差校正

针对十字形磁梯度张量系统中的单磁力仪误差(三轴灵敏度偏差、非正交误差和零点漂移误差)以及磁力仪之间存在的不对正误差,提出了十字形磁梯度张量系统的误差校正方法。首先,建立单磁力仪误差模型,采用基于椭球约束的最小二乘拟合算法对磁力仪的测量数据进行拟合从而得到椭球拟合参数;然后,接着利用Cholesky分解得到单磁力仪误差校正矩阵;最后在单磁力仪误差校正的基础上,利用正交Procrustes方法对不同磁力仪间的测量数据进行拟合从而得到磁力仪间的不对正误差校正矩阵。对提出的方法进行仿真与实测实验验证,实验结果表明:经过校正,磁梯度张量各分量的最大波动量由10 049nT/m降到52nT/m。提出的校正方法可以基本消除十字形磁梯度张量系统的误差,提高测量结果的准确度,且方法操作简单,不需要高精度的三轴无磁转台等设备,具有较高的实用价值。     

基于椭球拟合的三轴磁传感器快速标定补偿方法

考虑到现有多轴磁传感器的标定补偿方法中普遍存在操作时间长、计算量较大、标定设备要求高、场地要求面积大等问题,提出一种基于椭球拟合的三轴磁传感器误差标定补偿方法。首先,分析传感器误差产生机理,并在此基础上,建立传感器误差模型,推导出各误差系数的计算公式,并利用椭球拟合的方法对三轴磁传感器进行测试标定与误差补偿。实验结果表明,该方法能够正确、有效地标定补偿三轴磁传感器的不正交误差、灵敏度误差以及零偏误差,具有操作简捷、省时、精度高等特点。     

基于椭圆约束的新型载体磁场标定及补偿技术

在地磁导航中进行地磁测量时会受到载体磁场的影响,因此必须对测量数据中的载体磁场进行精确补偿,以提高磁场测量精度.本文根据硬磁材料磁场和软磁材料磁场的数学模型,提出了一种基于椭圆约束的载体磁场标定及补偿方法.该方法首先采用带椭圆约束的最小二乘拟合方法对捷联式磁传感器测量数据进行椭圆拟合,保证了拟合曲线必为椭圆,从而实现载体磁场的准确标定,然后利用标定参数实现对载体磁场的精确补偿.最后进行了一系列的仿真试验.试验结果表明了该方法具有简单快速,易于实现的特点,可以达到与磁传感器等精度的补偿效果,且在低信噪比情况下具有较强的鲁棒性     

Calibration of three-axis fluxgate magnetometers with nonlinear least square method

The accuracy of three-axis magnetometers is limited by different scales, bias of each axis and nonorthogonality between axes, which is usually lower than that of scalar magnetometers. In this paper, the nonlinear least square method is proposed to calibrate three-axis magnetometers. The validity of this method was proved by simulation, in which the estimated parameters of the error model are close to prearranged parameters. In experiment, a three-axis fluxgate magnetometer (DM-050), a two dimensional nonmagnetic rotation equipment and a proton magnetometer (GSM-19T) were used. The scalar value of magnetic field was obtained by proton magnetometer and considered to be the true value. The calibration performance of unscented Kalman filter (UKF), two-step algorithm and nonlinear least square were compared. Experimental results show that the error average and standard deviation of nonlinear least square are the least among the three methods. After calibration, the average of scalar error is reduced from −76.2 nT to −0.00093 nT and the standard deviation is reduced from 10.832 nT to 4.298 nT. The results suggest an effective way for the calibration of three-axis fluxgate magnetometers.     

Calibration strategy and generality test of three-axis magnetometers

Calibration strategy will influence the calibration performance of three-axis magnetometers. In this paper, three different calibration strategies (symmetrical calibration, orthogonal calibration and random calibration) are introduced and verified by simulation and experiments. The experimental system mainly consists of three-axis fluxgate magnetometer (MAG3300), 2D nonmagnetic rotation equipment and proton magnetometer. The scalar value of magnetic field was obtained with proton magnetometer and considered to be the true value. Calibration performance of three different calibration strategies were analyzed and compared. Experimental results show that after calibration the scalar RMS error has dropped 88.5%, 85.5% and 87.6% respectively. To check the generality of the estimated error parameters, another site was chosen to be a validation position, and the calibration performance of three calibration strategies were tested and compared. After calibration, the scalar RMS error has dropped 83.2%, 78.9% and 78.8% respectively. Thus the symmetrical calibration is considered to be the best calibration strategy among three calibration strategies.     

基于椭球假设的三轴电子罗盘罗差补偿研究

为实现三轴电子罗盘的自动罗差校正,对基于椭球假设的罗差补偿算法进行了研究.从描述载体干扰磁场的泊松模型出发,分析了椭球假设的合理性与局限性,给出了利用椭球拟合实现罗差补偿的算法,并进行了数值仿真及实验验证.实验结果表明,基于椭球拟合的罗差校正方法的剩余误差主要表现为常值误差与半圆罗差的结合,该方法可在无外部航向基准条件下实现三轴电子罗盘的自动罗差校正.     

A three-axes-compensated inductive magnetometer for measurements in high pulsed magnetic fields

A high-sensititity magnetometer intended for studying the magnetic properties of materials in pulsed magnetic fields of up to 43 T is described. A distinctive feature of the magnetometer is its method for compensating pickups generated in the magnetometer sensing element by a pulsed field. The commonly used uniaxial high-order compensation is replaced by a triaxial compensation of the lowest (quadrupole) order, combined with a transverse arrangement of the main probe coils. This method has allowed us to achieve a compensation level of the signal in the working coil (with an inner diameter of 1.4 or 1.75 mm) of the magnetometer without a sample of up to 10⁻⁶ for the longitudinal and 10⁻⁴ for the transverse field components. The magnetic moment sensitivity of the magnetometer is 10⁻⁴ mA·m² in fields below 10 T and 10⁻³ mA·m² at a field pulse amplitude of 35 T. A deviation of the compensation is below 2×10⁻⁴ for a temperature increase from 77 to 300 K and below 5×10⁻⁵ after sample replacement. The sample temperature is controlled by a fast-acting temperature control system in a range of 6–300 K to an accuracy of 0.3–0.05 K.