惯导系统横向坐标法导航性能研究

针对惯导系统横向坐标法,推导了惯导横向坐标系下的系统误差方程,通过求解静基座下的系统误差方程,研究了系统初始误差和惯性测量元件误差对基于横向坐标法的惯导系统的影响,在此基础上完成了系统误差仿真,并与地理经纬坐标解算方法进行比较。理论分析及仿真结果表明:横向速度误差、水平姿态误差为周期震荡型误差,位置误差和航向误差为随时间增长的积累型误差;横向坐标系法可以有效解决惯导地理经纬坐标解算方法的计算奇异和系统误差过大的问题。     

INS位置精度对GPS整周模糊度解算影响分析

在基于载波相位观测值的DGPS/INS组合导航中,GPS失锁重捕获时,仅利用自身的观测信息很难快速恢复整周模糊度,使用INS位置信息辅助GPS模糊度解算的方法可以有效解决这个问题。以模糊度精度衰减因子(ADOP)作为指标,分别研究了松组合和紧组合两种模式下INS位置精度与GPS模糊度解算成功率之间的关系。结果表明:中低精度的惯导设备能够有效减小ADOP值,提高GPS模糊度解算的精度及可靠性。     

一种提高导航精度的改进滤波方法

卡尔曼滤波技术是目前GPS/IMU组合导航中应用最广的误差估计关键技术之一。本文在捷联式惯导系统正向导航滤波算法与逆向导航滤波算法基础之上,提出一种将二者有机结合的组合滤波算法,用于事后IMU/GPS联合解算中,以提高组合导航的精度,并通过实际的机载飞行试验数据解算结果验证该方法的可行性。组合滤波后的位置精度达到厘米级,速度误差小于0.02 m/s,航向角精度约为0.2°。     

静基座捷联惯导解析法对准研究

初始对准是捷联惯导系统的关键技术之一,对准精度直接影响到导航系统的导航解算精度,静基座捷联惯导卡尔曼滤波法对准的精度和收敛时间受模型参数以及初始条件的影响,对于低精度的捷联惯导,这种影响更大,滤波结果往往不能收敛,甚至发散。采用解析法对准是解决上述问题的有效途径,针对静基座解析法对准做了系统研究,推导了惯性器件误差的解析表达式,分析了对准时间与仪器误差估计精度的关系。实测试验结果表明,给予适当的对准时间,解析法对准亦可接近极限精度;同时,在解析法初始对准中,等效天向加速度计零偏可得到有效估计;等效天向、北向陀螺漂移虽可估计,但随机游走对估计结果的影响不可忽视。     

一种基于加表零偏稳定性的GNSS/SINS组合导航异常探测方法

在地面车载组合导航中,全球导航卫星系统（global navigation satellite system,GNSS）的观测值容易受地面复杂环境的干扰,导致其定位结果出现异常,严重影响GNSS/捷联惯性导航系统（strap-down inertial navigation system,SINS）组合的滤波解算。从惯导系统误差特性的角度,研究了一种基于加表零偏稳定性的组合导航异常探测新方法。该方法从加表零偏解算的异常来发现GNSS位置、速度等观测值中的粗差,并采取剔除和降权的抗差方法抵御粗差影响。通过一组车载数据的分析表明,观测粗差对加表零偏解算的影响十分显著,以此为判别条件能够准确地发现观测粗差。采用该方法后,位置误差、速度误差和姿态误差的均方根分别减小了70.8%、87.9%和77.7%,显著提高了组合导航的解算精度和鲁棒性,为组合导航数据的抗差处理提供了一种新思路。     

基于惯性系原理的动基座粗对准及其性能影响因素分析

捷联惯导系统(strapdown inertial navigation system,SINS)在进行导航解算前需要粗对准提供初始姿态角,载体受多种因素影响和制约,在微幅晃动或运动状态下,需要进行动基座粗对准.从惯性系对准原理出发,讨论了基于比力和速度矢量的两种动基座粗对准解算方案,分析了位置误差、速度误差、杆臂误差对动基座粗对准的影响.结果表明,惯性系对准方法能够满足SINS粗对准的要求,速度误差和杆臂误差是制约对准精度与速度的主要因素,机动性强的轨迹能够加快对准速度,基于速度矢量的解算方案能够有效减弱姿态角收敛过程中的抖动,以提高对准效率.     

RTK/INS紧组合算法在卫星数不足情况下的性能分析

设计了一套基于集中式卡尔曼滤波的实时动态定位（real-time kinematic,RTK）/惯性导航系统（inertial navigation system,INS）紧组合算法,通过实测车载数据对比分析了3颗可用卫星时的固定解和浮点解在位置漂移误差水平和模糊度恢复时间上的差异,验证了该算法在卫星较少情况下的良好性能。该算法在即使观测卫星不足4颗时使用固定解或浮点解进行滤波更新,提高了组合导航在复杂环境下的位置精度,并加快了模糊度恢复过程。实验结果表明,使用中等精度的惯导,在可见卫星数为3颗时,失锁30 s时的水平位置漂移误差为0.3 m;失锁60 s内,平均1~2 s就能可靠地恢复整周模糊度。在位置漂移误差与模糊度恢复方面,固定解和浮点解在GNSS信号短期部分失锁时的差异并不显著,但同时都明显优于信号完全失锁情形。     

捷联式陀螺寻北系统两种解析寻北算法的比较与仿真

针对捷联式陀螺寻北倾斜误差补偿,对坐标变换法和矢量法两种解析调平算法进行推导,修正参考文献中有关矢量解析调平算法的错误;给出两种形式不同但寻北结果相同的解析调平解算公式,并对两种算法的寻北精度进行比较,仿真与试验结果表明了两种解析调平算法的正确性。     

露天矿区里程计辅助的GPS/INS车辆导航算法研究

由于INS误差容易快速积累,所以在GPS/INS组合导航过程中依赖于GPS信号的稳定性,露天矿区GPS信号容易发生中断或遮挡,引起INS误差的快速增长,降低导航精度。在GPS/INS组合导航的基础上,提出了露天矿区里程计辅助的组合导航算法,修正了GPS信号中断过程中导航参数误差。介绍了里程计速度和位置的解算方法和传统的GPS/INS组合导航的动力学模型及观测模型,给出了里程计辅助GPS/INS组合导航算法的结构图,描述了里程计辅助的GPS/INS组合导航算法的详细过程,通过车载验证了算法的有效性。实验结果表明:GPS信号缺失的情况下,GPS/INS组合导航的误差快速积累,导航精度较低;通过引入里程计辅助组合导航,可以及时修正GPS信号中断阶段的导航参数误差,加入的里程计辅助的GPS/INS组合导航误差在NED三个方向的最大值分别为11.336 m、8.056 m和19.782 m,比无里程计辅助的误差(在NED三个方向的最大值分别为40.324m、38.776m和79.693m)有较大提高,数据解算满足导航要求。     

惯性导航及其基于位置信息校正的关键技术研究

论文围绕惯性导航和基于位置信息的捷联惯导系统校正技术展开研究,内容涵盖了惯导系统的基本理论、惯性元件误差的分析与处理、静基座捷联惯导解析法对准、地固系捷联惯导系统关键算法、基于位置信息的捷联惯导系统综合校正技术等。     

GAINS中重力传感器信息的扰动改正

重力辅助惯性导航系统GAINS(Gravity Aided Inertial Navigation System)是利用地球物理特征信息──重力来完成水下运动载体的辅助惯性导航与定位。为实现重力匹配以校正惯性导航随时间累积的误差,首先必须对重力传感器输出信息进行扰动改正。分析了水下运动状态下重力传感器受到的各种重力扰动,如垂直扰动加速度、水平扰动加速度以及厄特弗斯效应影响所产生的原因,研究了扰动误差模型与INS导航精度之间的关系,并通过计算,提出了可直接以INS输出数据而无需其它外部有源导航信息进行扰动分离的方法。     

GAINS中重力传感器信息的扰动改正

重力辅助惯性导航系统GAINS(Gravity Aided Inertial Navigation System)是利用地球物理特征信息重力来完成水下运动载体的辅助惯性导航与定位.为实现重力匹配以校正惯性导航随时间累积的误差,首先必须对重力传感器输出信息进行扰动改正.分析了水下运动状态下重力传感器受到的各种重力扰动,如垂直扰动加速度、水平扰动加速度以及厄特弗斯效应影响所产生的原因,研究了扰动误差模型与INS导航精度之间的关系,并通过计算,提出了可直接以INS输出数据而无需其它外部有源导航信息进行扰动分离的方法.     

基于信噪比的InSAR干涉图自适应滤波

提出了一种基于信噪比的InSAR干涉图相位噪声抑制算法。该算法对Goldstein滤波方法进行了改进，使Goldstein滤波参数 依赖于局部信噪比，从而实现对低信噪比区域进行强滤波、高信噪比区域弱滤波。采用模拟数据和真实数据进行验证，结果表明新算法能有效抑制InSAR干涉图的噪声。     

New results in airborne vector gravimetry using strapdown INS/DGPS

A method for airborne vector gravimetry has been developed. The method is based on developing the error dynamics equations of the INS in the inertial frame where the INS system errors are estimated in a wave estimator using inertial GPS position as update. Then using the error-corrected INS acceleration and the GPS acceleration in the inertial frame, the gravity disturbance vector is extracted. In the paper, the focus is on the improvement of accuracy for the horizontal components of the airborne gravity vector. This is achieved by using a decoupled model in the wave estimator and decorrelating the gravity disturbance from the INS system errors through the estimation process. The results of this method on the real strapdown INS/DGPS data are promising. The internal accuracy of the horizontal components of the estimated gravity disturbance for repeated airborne lines is comparable with the accuracy of the down component and is about 4–8 mGal. Better accuracy (2–4 mGal) is achieved after applying a wave-number correlation filter (WCF) to the parallel lines of the estimated airborne gravity disturbances.     

重力场对惯性导航定位误差影响研究与仿真

从惯性导航力学编排方程出发,将高阶重力场模型代替正常重力模型,分析了扰动重力引起的惯性导航误差;并从另一角度,对理想状态下扰动重力对惯性导航的影响进行了仿真分析,结果表明扰动重力影响显著。通过将重力垂线偏差分量引入惯性导航方程,改善传统方程的缺陷,探讨了垂线偏差对惯性导航的影响。在全面论述了扰动重力和重力垂线偏差对惯性导航的影响的基础上,结合实际情况提出了进行重力场误差补偿的两种方法。     

重力场对惯性导航定位误差影响研究与仿真

从惯性导航力学编排方程出发,将高阶重力场模型代替正常重力模型,分析了扰动重力引起的惯性导航误差;并从另一角度,对理想状态下扰动重力对惯性导航的影响进行了仿真分析,结果表明扰动重力影响显著.通过将重力垂线偏差分量引入惯性导航方程,改善传统方程的缺陷,探讨了垂线偏差对惯性导航的影响.在全面论述了扰动重力和重力垂线偏差对惯性导航的影响的基础上,结合实际情况提出了进行重力场误差补偿的两种方法.     

A comparison of stable platform and strapdown airborne gravity

To date, operational airborne gravity results have been obtained using either a damped two-axis stable platform gravimeter system such as the LaCoste and Romberg (LCR) S-model marine gravimeter or a strapdown inertial navigation system (INS), showing comparable accuracies. In June 1998 three flight tests were undertaken which tested an LCR gravimeter and a strapdown INS gravity system side by side. To the authors' knowledge, this was the first time such a comparison flight was undertaken. The flights occurred in Disko Bay, off the west coast of Greenland. Several of the flight lines were partly flown along existing shipborne gravity profiles to allow for an independent source of comparison of the results. The results and analysis of these flight tests are presented. The measurement method and error models for both the stable platform and strapdown INS gravity systems are presented and contrasted. An intercomparison of gravity estimates from both systems is given, along with a comparison of the individual estimates with existing shipborne gravity profiles. The results of the flight tests show that the gravity estimates from the two systems agree at the 2–3 mGal level, after the removal of a linear bias. This is near the combined noise level of the two systems. It appears that a combination of both systems would provide an ideal airborne gravity survey system, combining the excellent bias stability of the LCR gravimeter with the higher dynamic range and increased spatial resolution of the strapdown INS. Received: 3 June 1999 / Accepted: 30 November 1999     

高精度惯性导航系统对重力场模型的要求

分析了采用现有重力场模型EGM96进行重力补偿和INS所能达到的定位精度,分析了实施GOCE任务和改进的重力场模型对INS的定位精度的影响,并给出了未来高精度纯惯导系统对重力场精度的要求.     

Flight test results from a strapdown airborne gravity system

In June 1995, a flight test was carried out over the Rocky Mountains to assess the accuracy of airborne gravity for geoid determination. The gravity system consisted of a strapdown inertial navigation system (INS), two GPS receivers with zero baseline on the airplane and multiple GPS master stations on the ground, and a data logging system. To the best of our knowledge, this was the first time that a strapdown INS has been used for airborne gravimetry. The test was designed to assess repeatability as well as accuracy of airborne gravimetry in a highly variable gravity field. An east-west profile of 250 km across the Rocky Mountains was chosen and four flights over the same ground track were made. The flying altitude was about 5.5km, i.e., between 2.5 and 5.0km above ground, and the average flying speed was about 430km/h. This corresponds to a spatial resolution (half wavelength of cutoff frequency) of 5.07.0km when using filter lengths between 90 and 120s. This resolution is sufficient for geoid determination, but may not satisfy other applications of airborne gravimetry. The evaluation of the internal and external accuracy is based on repeated flights and comparison with upward continued ground gravity using a detailed terrain model. Gravity results from repeated flight lines show that the standard deviation between flights is about 2mGal for a single profile and a filter length of 120s, and about 3mGal for a filter length of 90s. The standard deviation of the difference between airborne gravity upward continued ground gravity is about 3mGal for both filter lengths. A critical discussion of these results and how they relate to the different transfer functions applied, is given in the paper. Two different mathematical approaches to airborne scalar gravimetry are applied and compared, namely strapdown inertial scalar gravimetry (SISG) and rotation invariant scalar gravimetry (RISG). Results show a significantly better performance of the SISG approach for a strapdown INS of this accuracy class. Because of major differences in the error model of the two approaches, the RISG method can be used as an effective reliability check of the SISG method. A spectral analysis of the residual errors of the flight profiles indicates that a relative geoid accuracy of 23cm over distances of 200km (0.1 ppm) can be achieved by this method. Since these results present a first data analysis, it is expected that further improvements are possible as more refined modelling is applied. Received: 19 August 1996 / Accepted: 12 May 1997     

视觉辅助下的室内惯导位姿修正

惯性导航系统可以短期内提供连续的高精度信息，但是误差会随时间增大，不能长期独立工作。而在大型仓库、地下停车场等室内卫星信号薄弱的场景中，传统的惯导+卫星组合方法也不再适用。针对该问题，本文提出了一种视觉与惯导组合定位的方法。本文研究的惯导+视觉组合的定位方法中，采用基于合作目标的单目视觉定位方法对惯导误差进行修正。对于惯导误差的修正方法，本文利用视觉定位的位姿信息建立量测方程，进行卡尔曼滤波，并选取合适的试验设备，通过实际试验对比验证了该算法对惯导系统误差的修正具有良好的效果。