Error Analysis and Compensation of Strapdown Inertial Navigation System

Based on error analysis, the influence of error sources on strapdown inertial navigation systems is discussed. And the maximum permissible component tolerances are established. In order to achieve the desired accuracy (defined by circular error probability), the types of appropriate sensors are chosen. The inertial measurement unit (IMU) is composed of those sensors. It is necessary to calibrate the sensors to obtain their error model coefficients of IMU. After calibration tests, the accuracy is calculated by uniform design method and it is proved that the accuracy of IMU is satisfied for the desired goal.

A fast and accurate initial alignment method for strapdown inertial navigation system on stationary base

In this work,a fast and accurate stationary alignment method for strapdown inertial navigation system （SINS） is proposed. It has been demonstrated that the stationary alignment of SINS can be improved by employing the multiposition technique,but the alignment time of the azimuth error is relatively longer. Over here, the two-position alignment principle is presented. On the basis of this SINS error model, a fast estimation algorithm of the azimuth error for the initial alignment of SINS on stationary base is derived fully from the horizontal velocity outputs and the output rates, and the novel azimuth error estimation algorithm is used for the two-position alignment. Consequently, the speed and accuracy of the SINS＇ s initial alignment is enhanced greatly. The computer simulation results illustrate the efficiency of this alignment method.

An improved computation scheme of strapdown inertial navigation system using rotation technique

To improve the accuracy of strapdown inertial navigation system(SINS) for long term applications,the rotation technique is employed to modulate the errors of the inertial sensors into periodically varied signals,and,as a result,to suppress the divergence of SINS errors.However,the errors of rotation platform will be introduced into SINS and might affect the final navigation accuracy.Considering the disadvantages of the conventional navigation computation scheme,an improved computation scheme of the SINS using rotation technique is proposed which can reduce the effects of the rotation platform errors.And,the error characteristics of the SINS with this navigation computation scheme are analyzed.Theoretical analysis,simulations and real test results show that the proposed navigation computation scheme outperforms the conventional navigation computation scheme,meanwhile reduces the requirement to the measurement accuracy of rotation angles.

Fast Compass Alignment for Strapdown Inertial Navigation System

Initial alignment is the precondition for strapdown inertial navigation system(SINS)to navigate.Its two important indexes are accuracy and rapidity,the accuracy of the initial alignment is directly related to the working accuracy of SINS,but in self-alignment,the two indexes are often contradictory.In view of the limitations of conventional data processing algorithms,a novel method of compass alignment based on stored data and repeated navigation calculation for SINS is proposed.By means of data storage,the same data is used in different stages of the initial alignment,which is beneficial to shorten the initial alignment time and improve the alignment accuracy.In order to verify the correctness of the compass algorithm based on stored data and repeated navigation calculation,the simulation experiment was done.In summary,when the computer performance is sufficiently high,the compass alignment method based on the stored data and the forward and reverse navigation calculation can effectively improve the alignment speed and improve the alignment accuracy.

DESIGN AND REALIZATION OF SINS/TWO-ANTENNA GPS INTEGRATED NAVIGATION SYSTEM

The strapdown inertial navigation system （SINS）/two-antenna GPS integrated navigation system is discussed. Corresponding error and the measurement models are built, especially the double differenced GPS carrier phase model. The extended Kalman filtering is proposed. And the hardware composition and connection are designed to simulate the SINS/two-antenna GPS integrated navigation system. Results show that the performances of the system, the precision of the navigation and the positioning, the reliability and the practicability are im proved.

GNSS/SINS/视觉导航鲁棒算法

全球导航卫星系统(Global Navigation Satellite System, GNSS)、捷联惯性导航系统(Strapdown Inertial Navigation System, SINS)和视觉传感器优势互补,3者信息融合可获得高精度、无漂移的导航定位信息.针对GNSS/SINS/视觉融合导航易受运动速度、光照变化、遮挡等影响导致定位精度和鲁棒性降低问题,本文在图优化框架的代价函数中加入SoftLOne鲁棒核函数,设置量测值粗差检验程序,降低离群点带来的负面影响.进一步,对量测值计算残差进行卡方检验,对超限残差降权处理,提高系统精度和鲁棒性.实验结果表明,本文算法较不施加鲁棒核函数、不采用异常值剔除策略和卡方检验的传统算法,以及加入其他鲁棒核函数的算法精度更高、鲁棒性更好,能够较大程度提升GNSS/SINS/视觉导航定位精度和鲁棒性,在大尺度环境下,未出现较大漂移误差,绝对位姿均方根误差0.735 m,绝对位姿误差标准差0.336 m.

两种双矢量SINS粗对准方法大俯仰角适应性研究

大俯仰角下捷联惯导粗对准双矢量定姿中,不同矢量组合下,姿态角尤其是方位角对准精确度相差很大,必须慎重选择。对此,给出了2种最常用的粗对准矢量组合模式误差方程,对其主要误差影响因素进行分析。综合传感器误差,利用蒙特卡洛随机打靶方法对全姿态角下粗对准精确度进行仿真,并开展了80°俯仰角转台静态粗对准试验。转台试验中,在惯导陀螺误差约1°/h,加速度计误差约0.1mg情况下,第1种、第2种组合模式方位角粗对准最大误差值分别为20°、7.5°,第2种组合模式约为第1种的1/3;仿真测试中,在惯导陀螺误差约0.1°/h,加速度计误差约1mg,80°俯仰角下,第1种、第2种组合模式下方位角粗对准最大误差值分别为11°与2.2°,前者约为后者的5倍。仿真与试验结果表明,大俯仰角下矢量组合模式是影响惯导姿态角与姿态矩阵粗对准精确度的最主要因素。

一种基于深度学习辅助的SINS/DVL组合导航方法

水下机器人(autonomous underwater vehicle,AUV)导航定位精度一定上程度影响了AUV的工作效率,由于GNSS无法在水下使用,以捷联惯导系统/多普勒计程仪(SINS/DVL)的组合导航系统受到众多青睐。DVL在部分情况下会失效,若直接将DVL隔离,系统将变为纯惯性导航系统,严重影响导航定位的精度。为了应对DVL在部分波束缺失的情况,提出了一种DLinear-informer辅助组合导航算法。通过DLinear对原始输入数据特有的分解方式,增强了算法对AUV非线性信息的提取与学习,提高了速度预测精度。实验结果表明:所提算法能够准确预测DVL失效期间丢失波束的速度,降低组合导航的位置误差,提高了系统的鲁棒性和定位精度。

DVL/SINS松紧组合的等价性分析及改进的虚拟波束辅助紧组合算法

系统地研究了不同波束可用情况下的多普勒计程仪(Doppler velocity logger,DVL)/捷联惯性导航系统(strapdown inertial navigation system,SINS)紧组合导航算法。证明了3个或4个波束可用情况下,DVL/SINS波束域紧组合的定位精度与三维速度松组合系统具有等价性,并给出了松组合中量测协方差阵的确定方法。针对紧组合系统定位精度随可用波束减少而降低的问题,考虑DVL的误差参数,基于载体运动约束和压力深度计提出一种改进的虚拟波束辅助紧组合算法。实验结果表明,3个或4个波束可用时的松组合与紧组合的定位精度等价;改进的虚拟波束辅助紧组合算法可以准确跟踪故障的波束速度,有效提升了不同波束可用情况下紧组合的定位精度。

Three-time rapid transfer alignment method of SINS/GPS navigation system of high-speed marine missile

The transfer alignment of SINS/GPS navigation system of a high-speed marine missile was investigated. With the help of the big acceleration of a high-speed missile, the transfer alignment was changed into a three-time alignment. The azimuth alignment was coarsely finished in 10s in the first time alignment, the horizontal alignment was accurately and rapidly finished in the second time alignment, and the azimuth alignment was accurately finished in the third time alignment. Because the second time alignment and the third time alignment were finished by GPS after the missile was launched, the horizontal alignment and the second azimuth alignment got rid of the influence of the warship body flexibility deforming. The precision and rapidity of the horizontal alignment were prominently increased due to the vertical launch of the marine missile with the big acceleration. Simulation verifies the effectiveness of the proposed alignment method.

基于SINS/OD失准角观测的垂线偏差测量方法

组合导航系统的姿态失准角与垂线偏差(deviation of vertical,DOV)存在对应关系,通过对姿态失准角的观测是实现DOV测量的一种有效手段。本文基于车载捷联惯性导航系统/里程计(strapdown inertial navigation system/odometer,SINS/OD)组合导航姿态失准角观测及失准角误差的递推提出一种DOV测量方法。首先,从组合导航速度误差方程出发,推导出DOV与姿态失准角之间存在复杂的耦合关系。然后,通过沿路径迭代递推的分步计算方法,由导航过程中的姿态失准角直接获取沿线的DOV。最后,仿真结果验证了该算法的有效性,且表明测量精度与行驶路径的长度有关。实验表明,行驶里程35 km的机动路径上DOV误差均值小于0.3″,终点处单点测量误差小于0.7″。

Application of unscented Kalman filter to novel terrain passive integrated navigation system

To improve the navigation accuracy of an autonomous underwater vehicle （AUV）, a novel terrain passive integrated navigation system （TPINS） is presented. According to the characteristics of the underwater environment and AUV navigation requirements of low cost and high accuracy, a novel TPINS is designed with a configuration of the strapdown inertial navigation system （SINS）, the terrain reference navigation system （TRNS）, the Doppler velocity sonar （DVS）, the magnetic compass and the navigation computer utilizing the unscented Kalman filter （UKF） to fuse the navigation information from various navigation sensors. Linear filter equations for the extended Kalman filter （EKF）, nonlinear filter equations for the UKF and measurement equations of navigation sensors are addressed. It is indicated from the comparable simulation experiments of the EKF and the UKF that AUV navigation precision is improved substantially with the proposed sensors and the UKF when compared to the EKF. The TPINS designed with the proposed sensors and the UKF is effective in reducing AUV navigation position errors and improving the stability and precision of the AUV underwater integrated navigation.

SINS/GNSS自适应SRCKF直接式组合导航方法

针对动基座发射条件以及高动态、强干扰的运动环境下飞行器组合导航系统由于外界干扰导致滤波精度下降和鲁棒性差的问题,研究了一种发射惯性系下SINS/GNSS自适应SRCKF直接式组合导航方法。首先基于发射惯性坐标系构建了SINS/GNSS直接式组合导航模型,然后采用残差卡方检验法对量测信息失准情况进行判别,最后将衰减因子引入SRCKF算法中,自适应的在线调整滤波器的观测误差协方差阵以提升滤波精度。仿真结果表明:在量测噪声变化的情况下,相比于常规SRCKF组合导航算法,自适应SRCKF直接式组合导航算法位置、速度精确明显提升,可有效提升飞行器组合导航系统精度和鲁棒性。

Method of Improving the Navigation Accuracy of SINS by Continuous Rotation

A method of improving the navigation accuracy of strapdown inertial navigation system (SINS) is studied. The particular technique discussed involves the continuous rotation of gyros and accelerometers cluster about the vertical axis of the vehicle. Then the errors of these sensors will have periodic variation corresponding to components along the body frame. Under this condition, the modulated sensor errors produce reduced system errors. Theoretical analysis based on a new coordinate system defined as sensing frame and test results are presented, and they indicate the method attenuates the navigation errors brought by the gyros' random constant drift and the accelerometer's bias and their white noise compared to the conventional method.

SINS/CNS/GPS integrated navigation algorithm based on UKF

A new nonlinear algorithm is proposed for strapdown inertial navigation system （SINS）/celestial navigation system （CNS）/global positioning system （GPS） integrated navigation systems. The algorithm employs a nonlinear system error model which can be modified by unscented Kalman filter （UKF） to give predictions of local filters. And these predictions can be fused by the federated Kalman filter. In the system error model, the rotation vector is introduced to denote vehicle＇s attitude and has less variables than the quaternion. Also, the UKF method is simplified to estimate the system error model, which can both lead to less calculation and reduce algorithm implement time. In the information fusion section, a modified federated Kalman filter is proposed to solve the singular covariance problem. Specifically, the new algorithm is applied to maneuvering vehicles, and simulation results show that this algorithm is more accurate than the linear integrated navigation algorithm.

New rapid transfer alignment method for SINS of airborne weapon systems

Transfer alignment is an effective alignment method for the strapdown inertial navigation system （SINS） of airborne weapon systems. The traditional transfer alignment methods for large misalignment angles alignment use nonlinear transfer align- ment models and incorporate nonlinear filtering. A rapid transfer alignment method with linear models and linear filtering for ar- bitrary misalignment angles is presented. Through the attitude quaternion decomposition, the purpose of transfer alignment is converted to estimate a constant quaternion. Employing special manipulations on measurement equation, velocity and attitude linear measurement equations are derived. Then the linear trans- fer alignment model for arbitrary misalignment angles is built. An adaptive Kalman filter is developed to handle modeling errors of the measurement noise statistics. Simulation results show feasibili- ty and effectiveness of the proposed method, which provides an alternative rapid transfer alignment method for airborne weapons.

A tightly coupled rotational SINS/CNS integrated navigation method for aircraft

Strapdown inertial navigation system(SINS)/celestial navigation system(CNS)integrated navigation is widely used to achieve long-time and high-precision autonomous navigation for aircraft.In general,SINS/CNS integrated navigation can be divided into two integrated modes:loosely coupled integrated navigation and tightly coupled integrated navigation.Because the loosely coupled SINS/CNS integrated system is only available in the condition of at least three stars,the latter one is becoming a research hotspot.One major challenge of SINS/CNS integrated navigation is obtaining a high-precision horizon reference.To solve this problem,an innovative tightly coupled rotational SINS/CNS integrated navigation method is proposed.In this method,the rotational SINS error equation in the navigation frame is used as the state model,and the starlight vector and star altitude are used as measurements.Semi-physical simulations are conducted to test the performance of this integrated method.Results show that this tightly coupled rotational SINS/CNS method has the best navigation accuracy compared with SINS,rotational SINS,and traditional tightly coupled SINS/CNS integrated navigation method.

基于状态变换卡尔曼滤波的DVL/SINS组合导航算法

针对捷联惯性导航系统(strapdown inertial navigation system,SINS)误差定义存在的坐标系不一致的问题,将速度误差统一投影在真实导航坐标系中,基于状态变换Kalman滤波推导了更严密的SINS姿态、速度和位置误差方程。进一步地,在新定义的速度误差和SINS误差方程的基础上,构建了改进的多普勒计程仪(Doppler velocity logger,DVL)/SINS组合导航卡尔曼滤波状态模型和量测模型。仿真和船载实验表明,与常规DVL/SINS卡尔曼滤波模型相比,所提算法可以处理传统DVL/SINS误差模型中坐标系不一致问题的影响,可在一定程度上提高组合导航系统的性能。

复杂水下环境中自适应粒子群优化的SINS/DVL组合导航方法

针对复杂水下环境中基于捷联惯性导航系统/多普勒计程仪(SINS/DVL)组合导航系统受干扰导致定位精度下降的问题,提出一种自适应粒子群优化的SINS/DVL组合导航方法。首先,针对模型中方差估计不一致问题,构建了基于状态变换原理的SINS/DVL导航模型;其次,考虑到复杂水下环境中基于卡尔曼滤波的噪声难以估计问题,构造粒子滤波适应度函数,并设计了一种自适应粒子群优化算法;最后,对所提方法进行了仿真实验和湖试实验。实验结果表明:所提方法可以解决复杂水下环境中SINS/DVL组合导航系统受干扰导致定位精度不高的问题。相比于卡尔曼滤波方法、Huber鲁棒滤波方法,所提方法的水平位置误差最大值分别减少了49.56%和41.20%。

Evaluation and optimization of strapdown velocity numerical integration algorithms for SINS in spinning ballistic missiles

The error of the conventional velocity numerical integration algorithm was evaluated through the Taylor series expansion. It is revealed that neglecting the second- and higher-order terms of attitude increments will lead to the velocity numerical integration error, which is proportional to the triple cross product of the angular rate and specific force. A selection criterion for the velocity numerical integration algorithm was established for strapdown inertial navigation system (SINS) in spinning missiles. The spin angular rate with large amplitude will cause the accuracy of the conventional velocity numerical integration algorithm in SINS to decrease dramatically when the ballistic missile is spinning fast. Therefore, with the second- and higher-order terms of attitude increments considered, based on the rotation vector and the velocity translation vector, the velocity numerical integration algorithm was optimized for SINS in spinning ballistic missiles. The superiority of the optimized algorithm over the conventional one was analytically derived and validated by the simulation. The optimized algorithm turns out to be a better choice for SINS in spinning ballistic missiles and other high-precision navigation systems and high-maneuver applications.