Analysis and elimination of tri-band beacon interference with the fluxgate sensors onboard CSES

Science China Technological Sciences - High precision magnetometer (HPM) is a magnetic field detection payload onboard China Seismo-Electromagnetic Satellite (CSES), including two fluxgate...     

一种新型航姿系统

介绍了一种新型多功能惯性器件,它将双轴陀螺丐加速度计巧妙于民一体用它可构成新型垂直陀螺,再与磁通门传感器合成新型航姿系统,该系统能消除载体的变速运动对输出航姿角的影响,结构简单、紧凑,成本较低,可用于定向性移动卫星通信天线跟踪卫星的开环控制系统中。     

The state-of-the-art of the China Seismo-Electromagnetic Satellite mission

The China Seismo-Electromagnetic Satellite (CSES) mission was proposed in 2003 and approved in 2013 after ten years’ scientific and engineering demonstrations. To meet the requirement of scientific objectives, the satellite is designed to be in a sunsynchronous orbit with an altitude of 507 km and descending node time of 14:00 LT. The CSES satellite carries 8 instruments, including search-coil magnetometer (SCM), electric field detector (EFD), high precision magnetometer (HPM), GNSS occultation receiver (GOR), plasma analyzer package (PAP), langmuir probe (LAP), high energetic particle package (HEPP) and detector (HEPD), and tri-band beacon (TBB), among which HEPD is provided by Italian Space Agency. The CSES satellite was launched successfully on February 2, 2018, and is planned to operate for 5 years. The CSES mission is the first satellite in China to measure geophysical fields, which will have a lot of application prospects in the study of seismology, geophysics, space sciences, and so on.     

球体磁力异常三分量数据空间成像

目前的三分量磁测不同于以往地面磁法勘探中的水平分量、垂直分量或是磁异常总场的单一测量,而是同时测量出地磁场的三个分量（Za,Hax,Hay或T,D,I）的矢量测量,增加了来自于场源的信息量,并且三分量磁测数据具有矢量空间性,在图形成像方面可以克服单一分量平面图示的单调性,利用全空间矢量指向,可以提高对场源地质解释的可靠程度。本文基于球体模型来研究磁异常三分量的成像原理及特征规律,进而为研究实际磁源体奠定理论基础。首先正演计算出三个方向分量的数据为三维成像的绘制提供可靠保证,然后在Visual C＋＋6．0的MFC开发环境下,结合OpenGL的库函数进行三维图形的绘制。所编写的绘图软件可提供对应三分量磁力仪测量数据的成像功能,为三分量磁力仪的应用作一些基础性工作。     

基于最小二乘的多旋翼无人机磁力计动态校准

在静态校准的基础上提出一种小角度最小二乘迭代法,实现多旋翼无人机的磁力计动态实时校准.对于电机磁场以及环境磁场的干扰,连续采用最小二乘在小角度下拟合弧线并解算出球心,反复更新球心坐标,实现偏差修正,使多旋翼无人机在空中飞行时能够实时校准磁力计,进一步改善磁力计误差补偿问题.通过仿真和大量实验验证,该方法能有效地追踪零偏,解决多旋翼无人机的磁力计动态校准问题.     

微型磁通门传感器的激励仿真设计

微型磁通门传感器因具有功耗低、灵敏度高、分辨率高、结构简单和成本低等特点,被广泛应用于地球物理勘探、地磁导航、太空环境监测、医学诊疗等弱磁场测量领域。而对于该传感器,激励效果的好坏直接决定整套系统的性能,因而有必要为激励模块建立准确的仿真模型。基于法拉第电磁感应定律对双铁芯磁芯结构进行数学建模,并给出正弦波激励下电压、磁场量等物理量的波形。依据中国科学院地质与地球物理研究所研制的磁通门磁强计KDM-01的结构参数构建激励模块的仿真模型,得到的仿真结果与测试结果基本一致。并将该模型应用于设计的磁强计中,测试数据与标准磁强计非常近似。两者证明了所建立的数值模型的有效性和准确性。     

四川龙门山地区超长周期大地电磁探测

大地电磁超长周期信号是指1000~100000s之间的天然场源电磁波,为了提高对地下介质的探测深度和研究更深层的构造和结构,需要采集周期大于1000s的电磁场信号。2012年9~12月,笔者使用德国产ADU-07系统的感应式磁传感器和乌克兰产LEMI-417系统的磁通门在四川龙门山地区进行超长周期大地电磁数据采集实验,本文通过将感应式磁传感器和磁通门测试数据进行对比研究,探讨感应式磁传感器和磁通门的有效频谱范围,以及使用LEMI-417系统磁通门进行超长周期数据采集的可行性等,为推广和使用超长周期数据采集工作提供一个参考样本。     

混频弱磁信号的采集与处理

为了校准由八个磁通门传感器组成的传感器阵列的灵敏度,设计了一个磁传感器阵列校准系统.利用多通道数据采集卡对信号进行采集,使用快速傅里叶变换和三角积分法对数字信号分别进行了处理.结果表明,利用快速傅里叶变换,可以得到准确的、相互靠近的峰值频率,其范围介于3.8~4.2Hz之间,信号的振幅约为200nT,与理论计算值相差较大;采用三角积分法进行处理,可以获得功率谱密度,得到准确的信号振幅,与理论预测值的误差小于5%.     

基于磁强计的皮卫星姿态角测量误差

采用三轴磁强计测量地磁场矢量,与轨道演化和国际地磁场参考模型(IGRF)计算获得的地磁场矢量进行比较,获得姿态角度信息的方法适合体积小、重量轻、功耗低的皮卫星应用环境。地磁场矢量实际测量误差和轨道模型演化计算的地磁场矢量误差是皮卫星姿态角测量的两大误差源。通过分析获得磁强计A/D采样、磁传感器误差、温度漂移、铁磁材料等因素导致地磁场矢量实际测量误差为1.74°。皮卫星自身的特点不允许采用复杂的SPG4轨道演化模型,基于Kepler轨道模型和IGRF地磁场模型计算获得的地磁场矢量误差为0.5°。因此,基于三轴磁强计的皮卫星姿态角测量误差为2.24°。     

一种用于人体运动捕获的自适应混合滤波融合算法

针对基于惯性传感器的人体运动捕获系统存在陀螺漂移和噪声干扰等问题,提出一种多元传感器信息融合的自适应混合滤波融合算法。算法首先利用快速高斯牛顿法对加速度计和磁力计数据进行姿态信息迭代估算,用四元数将参考坐标系中的加速度和磁场强度分量转换到载体坐标中,将转换后的值与当前时刻测量值的差值代入高斯牛顿迭代算法中用于四元数的实时值估计,通过确定搜索步长的最优值来缩短迭代次数,提高算法收敛速度。设计自适应的互补滤波器将高斯牛顿法解算的姿态信息作为观测矢量对陀螺漂移进行补偿,分别使用高通滤波器和低通滤波器处理陀螺仪数据和高斯牛顿算法优化过后的加速度计、磁力计数据。在互补滤波器中引入重力矢量及地磁参考矢量自适应调节滤波器参数用于实时调整不同算法的权重大小,融合后输出最终的姿态信息,实现最优估计。进行实验对比分析本算法和其他算法融合效果,结果表明,本算法有效降低陀螺累积误差、线性加速度及磁场对解算精度的干扰,磁干扰状态下误差为0.94 °,自由运动状态下误差为1 °。对比扩展卡尔曼滤波融合算法,本文算法执行时间缩短25 %,有效提升了运动捕获系统的性能。     

临床患者体内金属异物快速排查定位装置设计

为实现患者体内金属异物的准确定位及术前术后手术器械的快速排查,设计了基于磁通门梯度测量方式的便携式装置.提出基于剩磁效应的铁磁性金属定位方法和基于电涡流效应的非铁磁性金属定位模式,用以解决传统磁通门无法感应非铁磁性金属的问题.采用改进的跑道型磁芯结构,选择钴基非晶合金Metglas2705M作为磁芯材料,以数字信号处理器为核心进行谐波提取和互相关滤波处理,提高了磁通门性能.通过建立信息数据库使该装置具有一定深度分析能力.15例异物患者临床实验证明,该技术便捷有效,有良好的临床应用前景.     

石油钻进中平行水平井垂直距离测定方法研究

针对蒸汽辅助重力泄油(SAGD)中注气井和产油井垂直距离的测距问题,提出了通过磁通门感应旋转磁信标中产生的交变磁场来进行垂直距离测距.并利用磁通门三轴感应输出值来计算2井眼之间的垂直距离,使注汽井和产油井的井眼轨迹保持在一定的范围内.由于钻具铁磁性材料会对距离测量产生误差,用当地磁场来对干扰磁场进行距离测量的校正,实验测量表明,该校正方法能在磁性材料干扰的环境下获得准确的垂直距离,具有简单、有效、实用的特征.     

基于二阶非线性滤波的星上陀螺在轨标定

为提高三轴稳定卫星姿态确定精度,针对典型的陀螺/星敏感器联合定姿方案,结合二阶非线性滤波估计,推导了一种利用星敏感器对陀螺进行实时在轨标定的算法.充分考虑卫星姿态测量过程中可能出现的各种误差源,建立陀螺安装误差、标定因子误差以及漂移模型,并对陀螺测量过程中可能出现的各种误差进行在轨补偿,为卫星姿态确定和校正提供丰富的姿态测量信息,以确保姿态测量器件长期在轨工作精度.采用该算法对哈尔滨工业大学"试验卫星一号"遥测数据进行复算和校核,结果与实际飞行数据吻合,验证了该在轨标定算法的有效性和可靠性.     

Design on a Multi-Sensor Integrated Attitude Determination System for Small UAVs

This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles（ UAVs）,which uses strapdown inertial navigation system（ SINS） based on micro electromechanical system（ MEMS） inertial sensors,commercial GPS receiver,and 3-axis magnetometer.MEMS-SINS initial attitude determination cannot be well performed for the reason that the MEMS inertial sensors biases are time-varying and poor repeatability,therefore in this paper the magnetometer and inclinometer are used to assist the MEMS-SINS initial attitude determination and MEMS inertial sensors field calibration.Furthermore,the attitude determination algorithms are presented to estimate the full attitude during GPS signal outage and non-accelerating situation.Additionally,the attitude information estimation results are compared with the reference of the non-magnetic marble platform and 3-axis turntable.Then the attitude estimation precision satisfies the requirement of attitude measurement for small UAVs during GPS signal outage and availability.Finally,the small UAV autonomous flight test results show that the low cost and real-time attitude determination system can yield continuous,reliable and effective attitude information for small UAVs.     

Initial scalar lithospheric magnetic anomaly map of China and surrounding regions derived from CSES satellite data

Science China Technological Sciences - The China Seismo-Electromagnetic Satellite (CSES), China’s first satellite to measure geophysical fields with scientific goals in both space and solid...     

Absolute radiometric calibration of CBERS-02 IRMSS thermal band

Based on the laboratory calibration before launch of CBERS-02 IRMSS thermal infrared channel, the onboard blackbody calibration, the radiometric crosscalibration against TERRA MODIS corresponding channel and the in-flight field calibration at Lake Qinghai: water surface radiometric calibration test site of China on Aug. 17, 2004 are carried out in this research. When making onboard blackbody calibration of CBERS-02 IRMSS, it is necessary to understand inside structures and light path in IRMSS camera and receive and process calibration blackbody signals at normal and high temperatures. Onboard blackbody calibration results of each detector are very important to relative radiometric calibration of images processing and absolute radiometric calibration of each detector. In-flight field calibration mainly contains field experiments, obtaining synchronous images, spectrum marching and MODTRAN radiative transmission computation. Radiometric cross-calibration of CBERS-02 IRMSS thermal band against TERRA MODIS selected 6 times synchronous images of two sensors passing through Lake Qinghai and Lake Taihu from August to December, 2004 to compute the cross calibration data. Combining the in-flight field calibration and radiometric cross calibration data, the absolute radiometric calibration coefficients are calculated by the linear regression method. This new calibration model can obviously control the radiometric calibration uncertainties aroused by the single point method used in the in-flight calibration of CBERS-02 IRMSS, this kind of sensors cannot receive the cosmic background radiation. In this research, the radiometric calibration coefficients obtained through the linear regression model are 8.53 (gain, unit: DN/W m^?2sr^?1μm^?1) and 44.92 (offset, unit: DN).     

基于无线惯性传感器的人体动作捕获方法

为解决光学式动作捕捉设备成本高昂和操作复杂的问题,提出一种通过佩戴在用户身体上的无线惯性传感器进行人体动作数据捕获的方法.在用户身体的各个运动部位绑定多个由加速度和磁通传感器构成的无线惯性传感器单元,传感器通过无线信号发送运动传感数据到计算机端,应用优化算法计算惯性传感单元的三维朝向信息,最后将四元数与动画角色的骨骼绑定后生成人体动作数据.为了解决运动过程中的行走导致的骨架根节点移动问题,利用地形参数反向计算和调整角色骨架根节点位置,使生成的动作符合地形和环境要求,达到真实自然的运动效果.实验结果表明,使用无线惯性传感器进行人体动作捕获得到的动作数据准确度高,朝向计算方法运行速度快,能够满足实时性应用的要求,同时显著降低动作捕获的成本和使用复杂度.     

航空磁力梯度张量测量——航空磁测技术的最新进展

评介了澳大利亚BHP比利顿矿产勘查公司和矿产发现技术公司的航空矢量磁测,美国地质调查所研制的地面张量磁梯度仪(用磁通门磁力仪),德国耶拿物理学高技术研究所的航空全张量磁力梯度仪系统(用LTS—SQUID),美国橡树岭国家实验室和特瑞斯坦技术公司(Tristan Technologies,Inc．)研究和开发的航空全张量磁力梯度仪系统(用HTS—SQUID),澳大利亚联邦科学工业研究组织(CSIRO)正在研制的航空张量磁梯度仪GETMAG和MAGSAFE(用HTS—SQUID),后者由CSIRO和澳大利亚国防科学与技术组织(DSTO)共同研制。提出了关于研究和开发我国航空磁测技术的建议．     

非实时控轨编队卫星的相对姿态控制

为了精确指向目标,即确定从星的姿态指向,提出了一种计算期望姿态和期望角速度方法,该算法利用单星在惯性坐标系的位置和速度,不需要星上增加相对姿态测量设备.在此基础上设计了变结构控制器.数值仿真结果表明该方法可以实现准确的期望姿态计算和相对姿态控制.     

The electromagnetic wave experiment for CSES mission: Search coil magnetometer

The seismic activities on the Earth can produce a disturbance of the electromagnetic field and particles in the ionosphere. The search coil magnetometer(SCM) mounted on China Seismo-Electromagnetic satellite(CSES) is designed to measure the magnetic field fluctuation of low frequency electromagnetic waves in the frequency range of 10 Hz–20 k Hz. The SCM comprises a three-axis search coil sensor mounted on a 4.5 m boom and an electronic box inside satellite module. The sampling rate of the SCM is 51.2 k Hz and the time resolution of the power spectrum density(PSD) is 2 s. The frequency resolution is 12.5 Hz.There are three operation modes: survey, detailed survey and calibration. In the survey mode, the SCM can provide a PSD in the whole frequency range of 10 Hz–20 k Hz and wave forms in the low frequency range below 2 k Hz while in the detailed survey mode the SCM can provide both PSD and wave forms in the whole frequency range of 10 Hz–20 k Hz. The sensitivity of the SCM instrument is 5.0×10~(-4) n T Hz~(-1/2) at 10 Hz, 5.0×10~(–5) n T Hz~(-1/2) at 200 Hz, 3.4×10~(-5) n T Hz~(-1/2) at 2 k Hz and 1.1×10~(-4) n T Hz~(-1/2) at 20 k Hz. The telemetry rate is ~0.85 Mbps in the survey mode and ~3.0 Mbps in the detailed survey mode. The phase difference between three axes can be made generally with a precision of less than 1.0°. The dynamic range of the SCM instrument is over 100 d B. The orthogonality of three mechanical axes of search coil senor is better than 0.13°. The performance of SCM can satisfy the requirement of scientific objectives of CSES mission.