The Improvement of a Low-Cost Inertial Navigator Through Conditional Feedback

A concept for providing an accurate low-cost inertial reference was presented in a previous paper. Low-cost platform gyros, poor in terms of their drift rates, furnish the space-fixed reference frame. A single high-accuracy gyro, mounted on the platform, monitors the performance of the platform gyros. Consequently, drift rates are estimated, predicted, and applied as signals to correct the platform for gyro uncertainties. This paper features new estimation and predictive techniques.     

线振动下惯导平台参数辨识的实现

研究了软性连接条件下线振动试验辨识惯导平台陀螺参数的方法。由于在此条件下原始模型不便用于辨识参数,为此提出了平台漂移的平均模型。对比静态模型指出了线振动对模型参数辨识的实质作用。由于利用平均模型来辨识平台参数存在参数冗余的局限性,因此利用两组不同幅值的线振动试验数据来进行辨识。最后验证了这种辨识方案不仅避免了静态条件下高阶陀螺参数难以收敛的问题,同时也解决了平均模型中参数冗余的局限性问题。     

Spectral Analysis of Optimal and Suboptimal Gyro Monitoring Filters

Gyro monitoring filters are used to estimate and correct gyro drift rates of local-level inertial navigation systems. Conventional gyro monitoring filters are usually designed based on a simplified model of gyro drift rate. Furthermore, the effectiveness of these filters-and of many filters of the "Kalman" type-is often measured in terms of the root mean square (rms) criterion in contrast to the spectral content criterion typical of classical Wiener filtering theory. This paper has two objectives: to propose a gyro monitoring filter which is based on a more detailed model of gyro drift rate; and to propose a method of filter performance evaluation which uses as criterion a measure of the spectral content of the error process. The proposed gyro monitoring filter is shown to have improved spectral contents resulting in superior navigation performance for the gyro error models used in the calculations (comparable to commercial-grade aircraft gyros).     

陀螺敏感轴交叉耦合对稳定平台角速度的影响分析

光电稳定平台中的陀螺装调误差影响平台角速度的测量精度。研究了速率陀螺稳定平台角速度的计算方法,重点是陀螺敏感轴交叉耦合情况下平台角速度的计算。得到了稳定平台角速度的理论计算公式,在此基础上,得到了理想情况和陀螺敏感轴交叉耦合情况下的测量计算公式。仿真和试验表明,对陀螺敏感轴的交叉耦合进行补偿,可以有效改善视线角速度的测量精度。     

稳定平台中陀螺漂移自适应实时估计算法

 针对陀螺稳定平台的漂移问题,建立了陀螺稳定跟踪装置在不同工作模式下陀螺漂移的数学模型,指出稳定模式下包含常值漂移和相关漂移的陀螺低频噪声是影响稳定精度的主要原因。提出一种自适应实时估计算法,采用卡尔曼滤波框架和滤波器收敛判据,结合Sage-Husa滤波和加权Sage-Husa滤波算法,利用跟踪器跟踪静止目标时输出的脱靶量信号对陀螺常值漂移和相关漂移进行估计。实验结果表明:该算法能够在系统模型和噪声特性均不准确的情况下使用,收敛时间小于3 s,估计均方差小于0.02 (°)/s,具有良好的鲁棒性和自适应能力。     

Ground Testing of Inertial Navigators to Improve Dynamic Performance

A ground testing method has been devised to evaluate the dynamic errors of an inertial navigation system. A trimmed stationary inertial system in the navigation mode can be subjected to programmed platform orm drift rates, and generate position outputs which are compared with those of a perfect navigator. The linearized error equations for this testing mode are derived and the resulting position error propagation is analyzed using Kalman filtering in order to identify the error sources. A simulated platform with a fixed set of error sources is analyzed to evaluate this testing concept. An example is presented to show that the gyro and accelerometer scale factor and misalignment error coefficients can be estimated.     

Principles Involved in the LM Rendezvous Radar Redundant Gyro System

For typical failure rates the probability of two or more of four gyros failing is very much less than one or both of two. Thus, a single redundancy system of four gyros greatly enhances system reliability. The orientation of the sensitive axes of four gyros is specified and means of generating outputs dependent only on gyro inconsistencies are defined. The voting logic and plots of switching decision zones are developed. The hardware required to implement this logic is shown to be simple and thus reliable. The use of rate integrating gyros requires the limitation of error integration time in order to avoid spurious failure signals. This is achieved by a reset cycle which realigns the four gyros at regular intervals. False error signals can be generated if inputs are large enough to exceed linear ranges of various components downstream of the gyros.     

低成本捷联惯导不对称动态误差的神经网络补偿

 针对低成本捷联惯导系统(SINS)中陀螺动态误差的不对称性在角振动条件下造成姿态漂移的问题,设计了多层前向神经网络的补偿模型。在标定模型参数时,为降低对外部参考信号测量精度的要求,提出用姿态解算的最终误差作为网络优化目标的训练方法。由于最终的姿态误差不是网络的期望输出,无法采用有导师的训练方法,为此采用了微粒群优化算法。仿真实验结果表明:补偿后的陀螺动态误差的不对称度减小了一个数量级。     

一种星敏感器-陀螺组合定姿的实时在轨标定方法

研究了一种星敏感器一陀螺组合定姿方式中的姿态敏感器误差的实时在轨标定方法。首先,选择直观的欧拉角作为姿态描述参数,根据星敏感器和陀螺的测量原理建立星敏感器一陀螺在轨标定的测量方程和状态方程,并以此建立数学模型。其次,采用简单高效的EKF（ExtendedKalmanFilter,扩展卡尔曼滤波）作为估值算法,进行了在轨标定数值仿真。对于航天器姿态定向中出现的姿态角和星敏感器安装角之间的耦合问题,通过在特定姿态通道上施加简单姿态机动实现了解耦。数值结果表明,该实时在轨标定方法,尤其是所提出的姿态角和星敏感器安装角解耦策略,可以实现对航天器姿态的实时精确估计以及对星敏感器安装误差、陀螺常值漂移和相关漂移等误差的实时在轨标定。该方法可用于航天器姿态测量设备的实时在轨标定和航天器姿态的高精度实时确定。     

空间光学平台调偏流分析

为减小偏流角对TDI-CCD(Time-Delay Integration-Charge Coupled Device,时间延迟积分-电荷耦合器件)相机成像的影响,分析了侧摆成像时偏流角产生的原因和计算方法,定量计算了偏流角在沿航方向和穿航方向产生的像移,并通过仿真分析了偏流角影响因素及其残差对成像的影响.最后通过实际飞行试验发现,平台调偏流时偏航方向的姿态角存在振荡,即偏流角存在残差.经分析,此现象产生原因除了卫星平台本身的姿态扰动外,主要是卫星平台响应机制,即卫星平台对调偏响应过慢导致平台调偏流出现超调现象.该分析结果对空间光学相机平台改进有一定的参考价值,并已应用于某型号卫星的改进型.     

Observer-based control for the platform of a tethered space robot

This paper addresses the attitude control problem of a space tethered robot platform in the presence of unknown external disturbance caused by a connecting elastic tether. The tether-generated unknown disturbance leads to tremendous challenges for attitude control of the platform. In this work, the perturbed attitude dynamics of the platform are derived with a consideration of the libration of the elastic tether, and then with the purpose of compensating the unknown disturbance, major attention is dedicated to develop a nonlinear disturbance observer based on gyros measurements, after which, an adaptive attitude scheme is proposed by combining the disturbance observer with a sliding mode controller. Finally, benefits from the observer based on an adaptive controller are validated by series of numerical simulations.     

弹性体上惯性测量系统的传递对准

 给出了一套弹性体上惯性测量系统的传递对准方案。该方法只采用角速度陀螺作为测量元件,能够对传感器误差进行补偿,并且可给出两套测量坐标系失配角的可靠估计。本文应用弹性力学的模态法建立机翼的运动方程;应用自适应Kalman滤波器在线估计由空气动力诱导的广义外力。     

基于卫星和星敏感器的冗余激光惯组在轨标定

采用高精度卫星导航速度、位置信息以及星敏感器提供的姿态信息设计十表冗余捷联惯组的标定模型,包含陀螺和加速度计的零次项和标度因数,对卫星和星敏感器辅助的冗余激光陀螺捷联惯组进行实时在轨标定.利用标准Kalman滤波和Sage-Husa自适应滤波作为估计算法,对十表冗余捷联惯组参数进行在线估计.数值仿真结果表明:参数标定精度均在7％以内,是一种实时的在轨标定方法,满足误差补偿要求.冗余惯组在轨标定方法为航天器高精度定姿和定轨提供了一种理论参考.     

Fast alignment and calibration algorithms for inertial navigation system

Algorithms for fast estimating the azimuth misalignment angle and calibrating gyro drift rates are approached from the point of view of control theory. By introducing the Lyapunov transformation, the equivalence of Strapdown Inertial Navigation System (SINS) and Gimbaled Inertial Navigation System (GINS) is discussed, and it shows that the analysis results of GINS can be applied to SINS directly by using such kind of equivalence. A similar transformation that based on physical essence is introduced, so that the true states can be replaced by the so-called pseudo-states, and then the observable states of INS can be dynamically decoupled with the unobservable states. Consequently, the best completely observable subsystem model of INS can be obtained. Based on the simplified subsystem model of INS, the algorithms for fast estimating the azimuth misalignment angle and calibrating gyro drift rates are proposed. The proposed algorithms show that the azimuth misalignment angle and gyro drift rates can be estimated from the rates of leveling misalignment angles without using the gyro output signals.     

低成本的多普勒-捷联惯性组合导航系统

本文研究了一种采用低精度的惯性器件,应用卡尔曼滤波技术的多普勒捷联惯性组合导航系统。讨论了组合方案,推导了系统的动态方程,设计了一种最优和四种次优卡尔曼滤波器。对系统进行了协方差分析。分析结果表明,采用随机漂移为0.1°/h的陀螺仪,零位误差为10^-4g的加速度计,应用卡尔曼滤波技术可以实现1nmile/h的导航精度,成为一种低成本、中等精度的导航系统。     

Attitude and Oribit Estimation Using Stars and Landmarks

An extended Kalman filter is used to process line-of-sight measurements to stars and known landmarks providing a statistical indication of performance in estimating spacecraft attitude, orbital ephemeris, and the bias drift of a set of three strapdown gyros. The landmark measurements were assumed to have been taken from the imagery of an Earth-observing multispectral scanner. It is shown that filtering of these noisy measurements results in highly accurate estimates of the above parameters. Results are given showing the sensitivity of performance to various system parameters such as star tracker accuracy, errors in the knowledge of landmark position, and number of stars and landmarks processed.     

多退化变量下基于Copula函数的陀螺仪剩余寿命预测方法

针对惯性导航系统中陀螺仪多退化变量条件下的剩余寿命（RUL）预测问题,提出了一种基于Copula函数的多退化变量剩余寿命预测方法。首先,针对退化变量间不同的退化轨迹,采用不同的方法进行退化建模,并对于陀螺漂移系数样本标准差数据波动性随时间递增的特性,提出了一种方差时变的正态随机过程退化建模方法,得到了陀螺仪剩余寿命的边缘分布函数。然后,通过Copula函数来描述退化变量之间的相关性,将得到的剩余寿命的边缘分布进行融合,得到了陀螺仪剩余寿命的联合分布函数。最后,通过陀螺仪实例分析验证了方法的适用性和可行性。     

检测质量对硅微机械框架振动陀螺影响的研究

 根据陀螺的动力学方程，从陀螺设计中的重要参数——内、外框架组件的等惯量约束条件和振动灵敏度等角度，探讨了检测质量对陀螺性能的影响，为微机械框架振动陀螺的设计提供了理论依据。     

Mini-UAV altitude estimation using an inertially stabilized payload

A novel method is introduced for autonomous attitude estimation of a mini unmanned aerial vehicle (UAV) carrying an inertially stabilized payload. The method is based on utilizing the outputs of rate gyros normally used to inertially stabilize the payload, and other data that is normally available from conventional aircraft-mounted sensors. A decentralized estimation algorithm is developed, which uses the aircraft/payload mathematical models to bound the estimation errors. Exploiting modern multiprocessor computer technology, the new estimation algorithm comprises two parallel extended Kalman filters (EKFs) and a data fusion algorithm. Real-time experimental tests, incorporating a payload model with real rate gyros mounted on a three-axis flight table, have validated the feasibility of the concept. The theoretical and experimental investigation demonstrates that the estimation algorithm is capable of estimating the attitude angles with an estimation error not exceeding 1 deg, at output rates of 13 Hz, thus constituting a viable substitute for the conventional vertical gyroscope     

适用于高精度惯性平台系统的精密加矩电路设计与实现

精密加矩电路通过给陀螺力矩器施加电流,驱动惯性平台系统相对惯性空间进行转动,其精度精度直接关系到惯性平台系统自标定与自对准精度能否实现。本文针对高精度惯性平台系统的需求,采用大电流粗加矩和小电流精加矩两种加矩电路的方式,兼顾了平台系统快速转位以及精确电流控制的要求。采用数字控制的二元调宽电路实现电流的精确控制。试验结果表明,精密加矩电路可以满足高精度平台系统自标定和自瞄准的要求。