Electrostatic accelerometer with bias rejection for gravitation and Solar System physics

Radio tracking of interplanetary probes is an important tool for navigation purposes as well as for testing the laws of physics or exploring planetary environments. The addition of an accelerometer on board a spacecraft provides orbit determination specialists and physicists with an additional observable of great interest: it measures the value of the non-gravitational acceleration acting on the spacecraft, i.e. the departure of the probe from geodesic motion.     

Kalman filtering for GPS/magnetometer integrated navigation system

This paper investigated the data processing method for a GPS/IMU/magnetometer integrated system with Kalman filtering (KF). As a result of GPS/IMU/magnetometer land vehicle system, dead-reckoning of magnetometer and accelerometer integrated subsystem bridged very well the GPS signal outage due to the trees on the two sides of the road. Both differential GPS data processing method and the carrier-phase method with magnetometers’ outputs for predicting the car position, velocity, and acceleration (PVA) are presented. The results from DGPS with Kinematical Positioning (KINPOS) software shown that the averages of the north, east, and down direction standard deviation (short for “std”) are 0.014, 0.010, and 0.018 m, respectively. The std of velocities and accelerations derived by the position and velocity differentiation are 10, 7, 13 mm/s, 7, 5, 9 mm/s², respectively. This method for getting velocities and accelerations requires higher accurate position coordinates. But the position accuracy has frequently been degraded in this case when the car drove under the trees or other similar kinematical environments. That caused the larger velocity and acceleration errors. While the results from the carrier-phase method are std of the velocities = 2.1 mm/s, 1.3 mm/s, 3.7 mm/s in north, east, down, and std of the accelerations = 1.5 mm/s², 0.9 mm/s², 2.3 mm/s² for the static test period; as compared with KINPOS software results, std of the velocity difference between the carrier-phase method and the DGPS method = 7 mm/s, 6.9 mm/s, 9.7 mm/s in north, east, down direction, and std of acceleration difference = 5.0 mm/s², 4.5 mm/s², 7.5 mm/s² in north, east, down direction for the kinematical test period. Obviously, errors come from both the carrier-phase method and DGPS velocity and acceleration results derived directly by the position differentiation. In addition, better accuracy of positions than that before KF has been got by means of velocities and accelerations derived by the carrier-phase method after KF.     

加速度表动态模型辨识和误差补偿

本文讨论全液浮陀螺加速度表的动态模型辨识及应用辨识所得模型进行动态跟踪误差补偿的方法。文章首先根据陀螺加速度表的动态模型估算了全程跟踪误差,其次介绍了脉冲传递函数参数的最小二乘估计和应用AIC准则来确定MA噪声的滑动阶数的原理。接下来讨论了用内环力矩器输入试验来实现辨识的可行性和实现辨识的一些问题。然后探讨了补偿动态跟踪误差的一些方法。最后对于一阶MA噪声情况应用增广最小二乘法进行了辨识仿真实验。仿真实验结果表明,全液浮陀螺加速度表的动态模型是可以辨识的。     

基于低精度离心机的平台惯导系统加速度计高精度系统级标定方法

高动态、大过载是未来导弹、飞行器的标志性特征,这一特征对惯导系统性能指标尤其是加速度计的性能指标要求尤为严苛.针对此,分析了平台惯导系统加速度计主要非线性误差(标度因数对称性和二次项系数)的传统离心标定方法的缺陷,提出了基于低精度离心机的平台惯导系统加速度计高精度系统级标定方法.该方法是利用惯导系统的速度和位置误差积分作为观测量进行Kalman滤波估计,不仅能对加速度计的非线性误差进行更有效估计,而且能克服传统离心标定方法对离心机的高精度要求.最后通过离心试验验证了该标定方法的有效性,试验结果表明,加速度计非线性误差补偿后的速度和位置误差小于补偿前相应误差的25％.     

GRACE accelerometer calibration by high precision non-gravitational force modeling

The precise modeling and knowledge of non-gravitational forces acting on satellites is of big interest to many scientific tasks and missions. Since 2002, the twin GRACE satellites have measured these forces in a low Earth orbit with highly precise accelerometers, for about 15?years. Besides the significance for the GRACE mission, these measurement data allow the evaluation of modeling approaches and the improvement of force models. Unfortunately, before any scientific usage, the accelerometer measurements need to be calibrated, namely scale factor and bias have to be regularly estimated.In this study we demonstrate an accelerometer calibration approach, solely based on high precision non-gravitational force modeling without any use of empirically or stochastically estimated parameters, using our in-house developed satellite simulation tool XHPS. The aim of this work is twofold, first we use the accelerometer data and the residuals resulting from the calibration to quantitatively analyze and validate different non-gravitational force model approaches. In a second step, we compare the calibration results to three different calibration methods from different authors, based on gravity field recovery, GPS-based precise orbit determination, and based on modeled accelerations.We consider atmospheric drag forces and winds, as well as radiation forces due to solar radiation pressure, albedo, Earth infrared and thermal radiation (TRP) of the satellite itself. For TRP, we investigate different transient temperature calculation approaches for the satellite surfaces with absorbed power from the aforementioned radiation sources. A detailed finite element model of the satellite is utilized for every force, considering orientation, material properties and shadowing conditions for each element.For cross-track and radial direction, which are mainly affected by the radiative forces, our calibration residuals are quite small when drag is not super dominant (1–3?$\text{nm}/{\text{s}}^2$ for total accelerations around $\pm$50?$\text{nm}/{\text{s}}^2$). For these directions the calibration seems to perform better than the other compared methods, where some bigger differences were found. For the drag dominated along-track direction it is vice versa, here our method is not sensitive enough because the difference between modeled and measured drag is bigger (e.g. residuals around 10?$\text{nm}/{\text{s}}^2$ for total accelerations around $\pm$70?$\text{nm}/{\text{s}}^2$ for low solar activity). In along-track direction the orbit determination based methods are more sensitive and produce more reliable results. Results for the complete GRACE mission time span from 2003 to 2017 are shown, covering different seasonal environmental conditions.     

2022年国外惯性技术发展与回顾

惯性技术广泛应用于海、陆、空、天各种载体的导航、定位与控制。通过对2022年的IEEE惯性传感器与系统会议、DGON惯性传感器系统会议、MEMS国际会议和圣彼得堡组合导航会议等惯性技术相关会议文献以及惯性技术领域相关机构披露的动态信息进行的详细梳理,总结了光学陀螺、微机电(MEMS)陀螺、半球谐振陀螺(HRG)、加速度计以及新兴的量子惯性传感器等惯性仪表及惯性导航系统(INS)的发展现状,并对惯性技术领域的发展趋势进行了分析与展望。当前,惯性技术领域相关研究主要侧重于小型化、提高精度和降低成本等方面。其中,光学陀螺较为成熟,更为侧重于小型化相关研究;微机电陀螺正在致力于向导航级性能突破和发展;半球谐振陀螺主要着力于探索降低高端产品的制造成本。     

精密离心机上加速度计安装姿态误差和主轴姿态误差对测试的影响

在精密离心机上进行加速度计测试和标定时 ,加速度计的安装姿态误差和精密离心机主轴姿态误差是影响加速度计测试和标定准确度的重要因素。给出这些姿态误差对加速度计测试的影响量 ,指出当这些姿态误差超过一定限度时要考虑这些姿态误差的影响 ,这对提高精密离心机上加速度计的测试和标定准确度将有非常重要的意义和实际应用价值     

九加速度计NGMIMU实用设计方案

无陀螺微惯性测量单元（NGMIMU）的九加速度计配置方案是该系统所有方案中运算量最小、最适合实时运算的。该方案要求若干加速度计安放在同一点上，但加速度计本身有体积，而且相对于实用载体而言其体积是巨大的，故导致巨大的系统误差。本文根据NGMIMU算法和加速度计特性提出一种全新的实用算法。该算法在要求加速度计安装满足一定条件的基础上，将多个加速度计进行分组计算，在没有增加任何计算量的情况下，从原理上消除了由于加速度计体积带来的误差。九加速度计NGMIMU实验结果显示，应用该算法测量误差小于8％，证明了该算法的正确性。     

Calibration method of quartz accelerometer on dynamic centrifuge

This paper proposes a novel method for calibrating error coefficients of the quartz accelerometer faster on the dynamic centrifuge, which can generate a continuous dynamic acceleration excitation. Firstly, working principle and structure of the dynamic centrifuge are analyzed, the error sources and the uncertainty of the dynamic centrifuge are expounded, and relevant coordinate systems are established. Then, according to the characteristics of the input specific forces and the propagating method...     

用离心机校准加速度计

介绍了校准加速度计的几种方法：地球重力校准法、负载校准法和离心机校准法。着重说明了离心校准法的基本原理、误差分析，以及注意事项和可达到的精确度。