GPS/INS integration on the Standoff Land Attack Missile (SLAM)

The Standoff Land Attack Missile (SLAM) is a worldwide, all-weather, precision-strike weapon system deployed from carrier-based aircraft. In the primary mode of operation, target location and other mission data are generated from intelligence sources available on the aircraft carrier and loaded into the missile prior to aircraft takeoff. After missile launch, the SLAM inertial navigation system (INS) guides the missile along the planned trajectory. Updating the missile INS from the Global Positioning System (GPS) during flight provides precise midcourse navigation and enhances target acquisition by accurate, on-target pointing of the SLAM Maverick seeker. The GPS/INS avionics and software integration used for SLAM are described in detail, along with some of the design tradeoffs that led to the approach. The avionics configuration integrates the Harpoon midcourse guidance unit, which includes a strapdown inertial sensor package and digital processor, with a Rockwell-Collins single-channel, sequential GPS receiver processor unit (RPU), a derivative of the GPS phase-III user equipment. In addition to the GPS receiver elements the RPU contains the navigation processor, which executes the SLAM navigation, Kalman filter algorithms, and other guidance algorithms including seeker pointing. Flight-test results of the SLAM GPS-aided INS are also included     

Fiber-optic strapdown inertial system with sensing cluster continuous rotation

This research describes a technique and a performance analysis of a fiber-optic strapdown inertial system with sensing cluster continuous rotation around the vertical body axis of the vehicle. The bias errors of these inertial sensors, gyros and accelerometers with cluster rotation, will have periodically varying corresponding components along the body axes. The modulated sensor errors produce reduced system errors. Simulation results indicate that, compared with the conventional method, the proposed approach attenuates the navigation errors and alignment errors due to the gyros' error and the accelerometers' error.     

旋转式SINS的自标校技术研究

惯性器件常值及慢变误差是影响捷联惯导系统精度的主要因素之一,所以在捷联惯导系统出厂前需要对常值及慢变误差参数进行标定。但这些误差参数会随时间发生变化,对于高精度捷联惯导系统,每次启动后需要对惯性器件的误差参数进行重新标校。针对光纤惯导系统,建立了IMU误差模型,并根据提出的旋转式捷联惯导系统自标校转位方案原则设计出了一种8位置自标校方案,对惯性器件标定参数进行激励和辨识,并建立了Kalman滤波状态方程及量测方程,对惯导系统误差参数进行在线标定。实验结果表明,该方案对其惯性器件误差参数能进行准确估计,具有一定的参考价值。     

极区格网阻尼导航方法

针对舰艇在极区航行时,其常用惯性导航系统机械编排存在精度下降、无北向基准等问题,设计了适用于极区工作的格网坐标系捷联惯性导航系统机械编排.在构建了格网坐标系参考框架的基础上,建立了格网坐标系捷联惯导系统的机械编排,并分析了其误差传播特性.通过误差分析,确定了格网坐标系捷联惯导系统中存在的周期性振荡,并提出了适用于格网坐标系捷联惯导系统的阻尼技术,有效抑制了周期性振荡.最后,通过仿真实验验证了该系统在极区工作的可行性和阻尼技术的有效性.     

An algorithm for astro-inertial navigation using CCD star sensors

A self-contained suite of astro-inertial navigation system is capable of autonomous mission and is operationally reliable. The typical astronavigation system (ANS) makes use of star-trackers, which are expensive and complex. To make the system cost effective and less complex, the star-tracker is replaced by a charge coupled device (CCD)-based star sensor, rigidly mounted on a strapdown inertial measurement unit (SIMU) of the system. This electro-optical star sensor is compact and easy to use with an ANS that utilizes efficient star identification techniques. This paper designs an algorithm that estimates axes misalignment angles of strapdown inertial navigation system (SINS) that makes stars' observations utilizing a CCD star sensor. Mathematical modeling of the suggested scheme was carried out and transformations between different frames were exercised. From the image projection geometry, stars' right ascensions and declinations, relative to the body frame, were estimated. Lastly, from the known stars' position vectors in mathematical platform and reference frames, axes misalignment matrix representing SINS attitude errors can be estimated employing the derived relationship.     

SINS/DVL水下组合导航系统的误差分析与改进技术

探讨了一种适用于SINS/DVL组合导航系统的滤波原理,通过分别建立捷联惯导系统误差模型和多普勒误差模型,利用间接卡尔曼滤波原理和反馈校正法,对系统进行仿真与分析,由惯性器件的误差方差通过导航系统的误差模型得出导航参数的误差方差,结果表明,该组合导航系统的定位精度要远远高于单纯捷联惯导系统。同时,针对SINS/DVL组合导航系统工作特点及特定情况下AUV的定位精度要求,提出了一种GPS辅助SINS/DVL组合导航系统导航定位的方案。     

空间平台机动变轨自主导航研究

针对空间平台在高轨道机动变轨过程中自主导航的需求,采用了基于Kalman滤波器的捷联惯导与星敏感器的组合导航方案。结合Kalman滤波中协方差更新的误差分配分析方法,分析了影响空间平台状态估计误差的主要因素。采用适用于高轨道的球谐重力模型,运用STK工具包设计了变轨机动轨迹,将该轨迹应用于组合导航方案的仿真验证。仿真结果表明,量测噪声是影响空间平台姿态精度的主要因素,加速度计零偏对变轨过程速度精度有决定性影响,改善两者的精度可以实现空间平台机动变轨的高精度自主导航。     

Hybrid Simulation System Study of SINS/CNS Integrated Navigation

In flight tests, to demonstrate the performance of integrated navigation systems, which are strapdown inertial navigation systems/celestial navigation systems (SINS/CNS), will involve a lot of effort and a heavy financial budget. So, it is important to design a functional self-contained hardware in a loop simulation system on the ground for solving the verification of SINS/CNS integrated navigation systems. Aiming at solving the main program, a high precision, versatile and better real-time performance hybrid simulation system of SINS/CNS integrated navigation is presented. The system adopts the design of hardware-functional modularization and software-flow integration, and makes use of a trajectory generator to produce simulated nominal trajectory data which is a uniform reference to signal process, and employs unique time synchronization algorithms to collect actual errors data of inertial sub-system and celestial sub-system. By combining with nominal trajectory data, the data smoothing, all-sky autonomous star map identification and integrated navigation algorithm based on unscented Kalman filtering (UKF), this system can accomplish a lot of system performance testing. It has the features of flexibility and extensibility and can be used to effectively reduce the experimental expense and shorten the development time of integrated navigation system, which is significant for studying algorithm performance, system speciality, and practical application of integrated navigation system.     

Systematic methods for knowledge acquisition and expert systemdevelopment [for combat aircraft]

Nine cooperating rule-based systems, collectively called AUTOCREW which were designed to automate functions and decisions associated with a combat aircraft's subsystems, are discussed. The organization of tasks within each system is described; performance metrics were developed to evaluate the workload of each rule base and to assess the cooperation between the rule bases. Simulation and comparative workload results for two mission scenarios are given. The scenarios are inbound surface-to-air-missile attack on the aircraft and pilot incapacitation. The methodology used to develop the AUTOCREW knowledge bases is summarized. Issues involved in designing the navigation sensor selection expert in AUTOCREW's NAVIGATOR knowledge base are discussed in detail. The performance of seven navigation systems aiding a medium-accuracy inertial navigation system (INS) was investigated using Kalman filter covariance analyses. A navigation sensor management (NSM) expert system was formulated from covariance simulation data using the analysis of variance (ANOVA) method and the ID3 algorithm     

基于组合导航技术的光纤捷联系统在线标定

 将光纤捷联系统惯性测量单元（IMU）输出误差分解成零偏误差、标度因数误差、失准角误差和随机白噪声几个部分,建立了系统误差模型,基于此模型设计卡尔曼滤波器引入高精度外部信息源对IMU进行在线标定。将此方法应用于某光纤捷联系统进行跑车试验,结果表明：引入外部信息源进行在线标定与补偿后系统纯惯导精度显著提高,本文建立的系统误差模型和在线估计方式有效估计了IMU输出误差,实现了系统在线标定,提高了系统实用精度。     

捷联惯性导航系统动静态误差特性分析研究

捷联惯性导航系统动静态误差特性是基于惯性的组合导航系统的主要误差来源。为此,根据捷联惯性导航系统的误差状态方程,本文分析了不同动静态情况下的捷联惯导系统的误差漂移特性。针对静基座和动基座的不同特点,分别采用了特征根和基于数值仿真分析的方法,并建立了相应的误差特性分析模型。重点研究了陀螺常值漂移、加速度计零位偏置和随机性误差对惯性导航系统误差漂移特性的影响;全面分析验证了惯性导航系统的动静态误差特性。本文的研究工作将为惯性组合导航系统误差分析建模提供了有益的参考。     

捷联惯性制导系统的圆锥误差及其补偿

圆锥误差是捷联惯导系统,特别是激光陀螺捷联惯导系统重要的误差源,为提高激光捷联惯性系统的导航精度,防止姿态误差的积累,本文研究了圆锥补偿算法和圆锥补偿误差特性,给出了常用的8种圆锥补偿算法,针对激光陀螺惯组的实际应用背景,开展了弹道仿真研究,给出了圆锥误差对激光陀螺捷联惯导系统导航精度的影响和补偿修正的效果。     

Strapdown inertial measurement units for motion compensation forsynthetic aperture radars

It is shown that synthetic-aperture radar (SAR) motion can be compensated by using an antenna-mounted strapdown inertial measurement unit (IMU) as the motion sensing system, but sensor and system errors affect SAR image quality. A strapdown IMU consists of three accelerator channels and three gyro channels. Strapdown IMU errors include gyro-scale and accelerometer-scale factor and bias errors, velocity error, platform tilt, and errors induced by limited inertial sensor bandwidth. The effects of these errors on the SAR image quality are presented in terms of the SAR impulse response. IMU errors that cause low-frequency phase errors (less than one cycle per array time) are categorized in terms of quadratic and cubic phase errors. IMU errors that cause high-frequency phase errors (greater than one cycle per array time) are categorized in terms of the integrated sidelobe ratio and peak sidelobe ratio. A motion compensation system conceptualization is described wherein a strapdown IMU is attached to an antenna and transfer-aligns to the aircraft's master navigator     

车载捷联惯导与里程计组合导航技术研究

惯导的误差随着时间增长是积累的,可采用里程计辅助捷联惯导构成纯自主的车载组合导航系统.利用捷联惯导的速度和里程计测量的速度之差作为观测量,通过卡尔曼滤波技术校正惯导的导航参数,可以有效地抑制惯导误差的积累,提高导航参数的精度.本文推导了组合导航系统的模型,从理论上用特征值方法分析了系统的可观测度,进而设计轨迹进行了仿真...     

捷联惯导系统误差特点分析

对捷联惯导系统的误差源进行了深入分析,结果表明当陀螺仪刻度系数误差较大时,捷联惯导系统定位误差闭合现象较明显,即飞机返场时,误差有明显减小的现象;分析了舒拉调谐周期对惯导系统位置误差的影响并进行仿真,仿真结果验证了舒拉调谐对误差的调制作用,即在舒拉周期振荡分量的影响下,惯导系统的累积误差在某段时间内存在误差减小现象。     

基于奇异值分解的组合导航可观测度计算

以捷联惯组为主惯导的组合导航系统具有短时定位精度高、可靠性强等优点,但其依然存在长时间导航精度不高、运算量大、组合效率不高等问题。为更好地完善组合导航系统的误差补偿和抑制技术,对SINS/DVL组合导航系统的可观测性能进行了研究。在分段定常系统(Piece-wise Constant System,PWCS)的可观测性分析方法及基于奇异值分解的系统状态可观测度分析方法基础上,结合可观测性矩阵的遗传特性,提出了一种简化的状态量可观测性分析方法,并对该方法进行了理论仿真。为方便比较状态量的可观测程度,对各状态的可观测度进行了归一化处理。最后,通过湖面跑船实验设计了不同的航迹机动方式,计算了关键导航参数的可观测性能。实验证明,该方法可以实时计算组合导航参数的可观测度,根据可观测度设计的航迹可以有效提高导航精度,定位精度可提高1个量级,收敛速度也获得了明显提高。     

基于速度误差的系统级标定方法

为降低捷联惯导系统误差参数标定过程对高精度转台的要求,提出一种基于速度误差的系统级标定方法。在惯性器件误差参数模型和捷联惯导系统误差方程的基础上,以惯导系统转动前后的导航速度误差为观测量,编排设计旋转方案,对加速度计和陀螺的误差参数进行拟合标定。仿真结果表明,与传统的分立式标定方法相比,在保证标定精度的同时,对高精度转台的要求更低,可应用于外场标定。     

Strapdown INS error model for multiposition alignment

The relationship between quaternion errors and tilt angles from true navigation frame to analytic platform frame is newly derived for strapdown inertial navigation system (SDINS). Using the relationship it is shown that the quaternion error model for attitude and velocity is equivalent to the conventional perturbation error model. Based upon the equivalency, the quaternion errors during a multiposition alignment are determined and analyzed. Furthermore, it is shown that the heading rotation of 180 deg achieves the minimal quaternion error for 2-position ground alignment     

捷联惯导姿态算法中的圆锥误差与量化误差

对捷联惯导系统的误差源进行了研究,利用几何方法分析了不可交换性误差和量化误差的形成机理,以及它们的相互影响。针对工程应用中激光陀螺输出脉冲采样量化条件,就多子样算法进行了讨论,并设计了基于MATLAB/Simulink的仿真。研究结果表明,当考虑量化误差的影响时,选取适当的量化因子,三子样等效旋转矢量算法比其它算法具有更好的综合性能。     

Strapdown inertial navigation using dual quaternion algebra: error analysis

In a strapdown inertial navigation system (INS), the general displacement of a rigid body is traditionally separately modeled and analyzed, i.e., direction cosine matrix or quaternion for rotation analysis and vector for translation analysis. As a subsequent work of a companion paper (Wu et al., 2005), this paper adopts dual quaternion algebra, a most concise and unified mathematical tool for representing the general displacement of a rigid body, to analyze error characteristics of the strapdown INS. Two new error models in terms of quaternion algebra are developed: the additive dual quaternion error (ADQE) model and multiplicative dual quaternion error (MDQE) model. Both are expected to facilitate the future inertial navigation-based integrated navigation filter.