高精度光纤陀螺信号的在线建模与滤波

针对高精度光纤陀螺随机误差,在分析其一般时间序列模型的基础上,提出了一种改进型二阶自回归AR(2)模型,可以在线建立光纤陀螺随机误差模型.根据该模型,采用卡尔曼滤波算法,实现了光纤陀螺惯导系统在对准与导航过程中光纤陀螺随机误差的实时滤波.滤波结果和Allan方差分析证明,光纤陀螺信号中角随机游走、零偏不稳定性、速率随机游走、速率斜坡和量化噪声五项噪声源误差系数都小于滤波前的二分之一,有效减小了光纤陀螺随机误差,提高了光纤陀螺精度.     

Vehicle Localization Using Sensors Data Fusion Via Integration of Covariance Intersection and Interval Analysis

Achieving an innovative integrated sensor fusion architecture with a robust vehicle navigation and localization using an extended Kalman filter, interval analysis and covariance intersection that can overcome the uncertainty in the system model and sensor noise statistics. There are various approaches to the problem, but here the focus is on an approach which can guaranteed performance of sensor-based navigation. The guaranteed performance is quantified by explicit bounds of position estimate of a ground vehicle. Ground vehicles generally carry dead reckoning sensors such as wheel encoders and inertial sensors, to measure acceleration and angle rate, while obstacle detection and mapmaking is done with time-of-flight ultrasonic sensors. Most of these sensors give overlapping or complementary information and sometimes are redundant as well, which offers scope for exploiting data fusion. The purpose here is to achieve data fusion for ground vehicles with low-cost sensors by forming an intelligent sensor system. This is accomplished by combining the sensors' measurements and processing these measurements with data fusion algorithms. The algorithms are complementary in the sense that they compensate for each other's limitations, so that the resulting performance of the sensor system is better than its individual components.     

Robust positioning technique in low-cost DR/GPS for land navigation

This paper describes a dead-reckoning (DR) construction for land navigation and sigma-point-based receding-horizon Kalman finite-impulse response (SPRHKF) filter for DR/GPS integration system. A simple DR construction is adopted to improve the performance of both pure land DR navigation and DR/GPS integration system. In order to overcome the flaws of the extended Kalman filter (EKF), the sigma-point KF (SPKF) is merged with the receding-horizon strategy. This filter has several advantages over the EKF, the SPKF, and the RHKF filter. The advantages include the robustness to the system model uncertainty, the initial estimation error, temporary unknown bias, etc. The computational burden is reduced. Especially, the proposed filter works well even in the case of exiting the unmodeled random walk of the inertial sensors, which can occur in the microelectromechanical systems' inertial sensors by temperature variation. Therefore, the SPRHKF filter can provide the navigation information with good quality in the DR/GPS integration system for land navigation seamlessly.     

基于阿伦方差的微机电陀螺误差建模及其粒子滤波

基于Allan方差对微机电陀螺的随机漂移误差进行分析和建模,并通过粒子滤波提高了微机电陀螺的零偏稳定性.实验结果表明,这种方法比较简单而切实可行,可以明显提高微机电陀螺仪的零偏稳定性.     

Evaluation of a solid-state gyroscope for robotics applications

The evaluation of a low-cost solid-state gyroscope for robotics applications is described. An error model for the sensor is generated and included in a Kalman filter for estimating the orientation of a moving robot vehicle. Orientation estimation with the error model is compared to the performance when the error model is excluded from the system. The results demonstrate that without error compensation, the error in idealization is between 5-15°/min but can be improved at least by a factor of 5 if an adequate error model is supplied. Like all inertial systems, the platform requires additional information from some absolute position-sensing mechanism to overcome long-term drift. However, the results show that with careful and detailed modeling of error sources, inertial sensors can provide valuable orientation information for mobile robot applications     

Lever Arm Compensation of Autonomous Underwater Vehicle for Fast Transfer Alignment

Transfer alignment is used to initialize SINS (Strapdown Inertial Navigation System) in motion. Lever-arm effect compensation is studied existing in an AUV (Autonomous Underwater Vehicle) before launched from the mother ship. The AUV is equipped with SINS, Doppler Velocity Log, depth sensor and other navigation sensors. The lever arm will cause large error on the transfer alignment between master inertial navigation system and slave inertial navigation system, especially in big ship situations. This paper presents a novel method that can effectively estimate and compensate the flexural lever arm between the main inertial navigation system mounted on the mother ship and the slave inertial navigation system equipped on the AUV. The nonlinear measurement equation of angular rate is derived based on three successive rotations of the body frame of the master inertial navigation system. Nonlinear filter is utilized as the nonlinear estimator for its capability of non-linear approximation. Observability analysis was conducted on the SINS state vector based on singular value decomposition method. State equation of SINS was adopted as the system state equation. Simulation experiments were conducted and results showed that the proposed method can estimate the flexural lever arm more accurately, the precision of transfer alignment was improved and alignment time was shortened accordingly.     

基于正交原理与仿真的单屏蔽温度传感器误差影响因素研究

为了辨析相关影响因素对单屏蔽温度传感器测温误差的影响程度,以便为传感器的优化设计提供必要信息,本文介绍了马赫数、来流总温、来流压力、环境壁温、传感器耙身温度等五个可能的影响因素。借鉴正交原理的思想完成各因素条件值选择,采用数值仿真的方法获取了所选传感器的误差信息,完成了误差数据的极差与方差分析,排列出了所举误差影响因素的主次关系,并得出总温与压力对测温误差有显著影响的结论。     

Non-Exchangeable Error Compensation for Strapdown Inertial Navigation System in High Dynamic Environment

Strapdown non-exchangeable error compensation technology in high dynamic environment is one of the key technologies of strapdown inertial navigation system. Mathematical platform is used in strapdown inertial navigation system instead of physical platform in traditional platform inertial navigation system, which improves reliability and reduces cost and volume of system. The maximum error source of attitude matrix solution is the non-exchangeable error of rotation due to the non-exchangeable of finite rotation of rigid bodies. The rotation non-exchangeable error reaches the maximum in coning motion, although it can be reduced by shortening the correction period and increasing the real-time calculation. The equivalent rotation vector method is used to modify the attitude to reduce the coning error in this paper. Simulation experiments show that the equivalent rotation vector method can effectively suppress the non-exchangeable error and improve the accuracy of attitude calculation.     

中航时平台惯导系统导航精度的全误差评估方法

平台惯导系统(PINS)初始对准误差和标定参数重复性是评估PINS精度的主要参数.应用给定精度评定指标无法准确评估PINS导航精度,PINS全误差导航模型能够准确描述PINS误差传播过程,但对多批次中航时PINS精度评估需消耗大量时间,缺乏实用性.结合实际应用中需要对每一台PINS中航时导航精度进行快速准确评估的需求,通过对PINS全误差导航模型传播规律进行分析,得到PINS误差参数对导航精度的单项评估公式和简化综合评估公式.数值仿真验证表明:该方法能够对中航时PINS导航精度进行快速准确估算,在PINS选择中具有很好的实用性.同时该方法可以指导惯导系统生产调试,找到影响惯导系统的主要误差因素,对改进设计、提高精度和精度评定具有参考价值.     

Joint-Angle Measurement Using Accelerometers and Gyroscopes—A Survey

This paper presents an analysis of rigid-body joint-angle measurement based on microelectromechanical-system (MEMS) biaxial accelerometers and uniaxial gyroscopes. In comparison to conventional magnetic and optical joint angular sensors, this new inertial sensing principle has the advantages of flexible installation and true contactless sensing. This paper focuses on the comparison of four different inertial-sensor combination methods that are reported in reference papers and utilizes the theory of rigid-body kinematics to explain and analyze their advantages and weaknesses. Experiments have also been conducted to further verify and strengthen the arguments put forward in the analysis. All experiments in this paper took place on a custom-built rigid-body robot arm model that can be manipulated by hand. Sensor calibration and accelerometer alignment issues are also described, and their details are discussed. The experiment results presented in this paper show significant differences with reference to the achieved angular accuracy for various situations when using the four different sensor combination methods. In some cases, the angular error based on one method is more than 0.04 rad, while that from another method is within $pm$0.005 rad. The noise levels of angular readings from different methods are also experimentally compared and analyzed. The conclusion drawn serves to guide readers toward a suitable method for their particular application.      

Statistical biases and very-long-term time stability analysis

The prediction of very-long-term time stability is a key issue in various fields, such as time keeping, obviously, but also navigation and spatial applications. This is usually performed by extrapolating the measurement data obtained by estimators such as the Allan variance, modified Allan variance, Hadamard variance, etc. This extrapolation may be assessed from a fit over the variance estimates. However, this fit should be performed on the log-log graph of the estimates, which corresponds to a least-squares minimization of the relative difference between the variance estimates and the fitting curve. However, a bias exists between the average of the log of the estimates and the log of the true value of the estimated variance. This paper presents the theoretical calculation of this log-log bias based on the number of equivalent degrees of freedom of the estimates, shows simulations over a large number of realizations, and provides a reliable method of unbiased logarithmic fit. Extrapolating this fit yields a more confident assessment of the very-long-term time stability.     

由相位噪声间接测量阿伦方差的研究

振荡器的频率稳定度在时域一般用阿伦方差表征,在频域一般用相位噪声谱密度函数表征,两者存在一定的数学转换关系,即可以由频域测量的相位噪声谱密度函数转换为时域的阿伦方差.t<0.1 ms时短期频率稳定度的时域测量非常困难.利用两者之间的转换关系对振荡器的时域稳定度进行了间接测量,并用实测数据进行了验证.     

基于GPS与惯性组件的复合测姿系统设计

针对微小型载体空间有限而无法安装大型测姿系统,提出了一种低成本的微型复合测姿方案.复合测姿系统由单天线GPS和MEMS惯性组件构成.利用扩展卡尔曼滤波将单天线GPS和MEMS惯性组件信息融合,提高了姿态估计精度.室外车载实验结果表明,利用该复合测姿系统解算的滚角和俯仰角误差可控制在1°以内,航向角误差可控制在2°以内.     

A Direct Time-Domain Measure of Frequency Stability: The Modified Allan Variance

A simple filter is shown to closely approximate the procedure used to compute the "Allan variance," an often used measure of the short term frequency stability of oscillators. This modified Allan variance is obtained by measuring the rms value of the instantaneous frequency waveform after filtering. Some advantages of the modified Allan variance include ease of implementation for short averaging times and better behavior when the instabilities include periodic components. The effect of the bandwidth of the measuring process on the minimum usable averaging time is also discussed.     

激光捷联惯导系统中惯性器件的测试方法

为了提高激光捷联惯导系统(LSINS)的导航精度,需要测试系统中惯性器件的模型参数。本文设计了一种利用双轴带温控箱速率转台的参数测试方法,测得了系统在各种环境温度下的参数。通过建模补偿有效地减小了LSINS的导航误差。实验结果表明本方法标定精度较高,适用于中等精度LSINS。     

惯导系统传递对准精度实验的半物理仿真方案

提出了一种惯导系统传递对准精度试验的半物理仿真方案,该方案可用于评估空空导弹捷联惯导系统的传递对准精度.该半物理仿真系统模拟空中传递对准的"真实过程",评估出导弹惯导系统相对于基准系统的失准角,搭建了给予该方案的半物理仿真试验系统.经在某型惯导产品的传递对准精度试验中的实际应用,表明该方案是可行的和实用的.     

总方差方法在光纤陀螺随机误差分析中的应用

总方差方法被引入到光纤陀螺随机误差特性分析当中,有效克服了传统 Allan方差法在长相关时间上计算易出现“崩溃”的问题。但用它直接分析光纤陀螺随机噪声存在算法偏差,不能真实反映角度随机游走噪声、量化噪声和指数相关噪声方差值,因此在算法上对总方差提出改进,使其适用于光纤陀螺噪声分析。对模拟的各项随机噪声进行仿真计算,验证改进后总方差方法可有效辨识噪声类型和水平。对光纤陀螺实测数据方差分析表明改进的总方差方法在平均因子较大的情况下可提高估计置信度,方差值稳定性好,比 Allan方差法能更精确地分析出噪声项系数。     

Alternating current investigation and modeling of the temperature and ozone effects on the grains and the grain boundary contributions to the WO3 sensor responses

We report a parametric investigation of the electrical property evolution of WO₃ thin films in ozone. The effect of working temperature and ozone concentration on sensors' sensitivity has been studied by alternating current (AC) impedance spectroscopy. An electrical model of resistance and capacitor circuit was used to fit the experimental spectra. It was demonstrated that the best sensors' sensitivity is obtained in the working temperature range of 250 to 300 °C. A tentative interpretation of the sensors' response evolution has been made by modeling of the ozone concentration effect on the WO₃ sensitive layer impedances after obtaining additional AC measurements. The contributions of the grains and grain boundaries to the overall response of the WO₃ based sensors were dissociated.     

等效旋转矢量法在旋转弹姿态解算中的应用

作为捷联惯导的核心问题,姿态更新算法的选择至关重要.针对旋转弹的姿态测试问题,在四元数增量算法的基础上利用等效旋转矢量法对姿态进行优化,给出了姿态解算的数学模型.仿真结果显示,该算法对不可交换误差的抑制效果明显,同时,在一定程度上减小了累积误差,提高了导航精度.     

Distributed data fusion algorithms for inertial network systems

New approaches to the development of data fusion algorithms for inertial network systems are described. The aim of this development is to increase the accuracy of estimates of inertial state vectors in all the network nodes, including the navigation states, and also to improve the fault tolerance of inertial network systems. An analysis of distributed inertial sensing models is presented and new distributed data fusion algorithms are developed for inertial network systems. The distributed data fusion algorithm comprises two steps: inertial measurement fusion and state fusion. The inertial measurement fusion allows each node to assimilate all the inertial measurements from an inertial network system, which can improve the performance of inertial sensor failure detection and isolation algorithms by providing more information. The state fusion further increases the accuracy and enhances the integrity of the local inertial states and navigation state estimates. The simulation results show that the two-step fusion procedure overcomes the disadvantages of traditional inertial sensor alignment procedures. The slave inertial nodes can be accurately aligned to the master node.