【作者】 韩松来；

【导师】 高伯龙；

【作者基本信息】 国防科学技术大学 ， 光学工程， 2010， 博士

【摘要】 传统的GPS和捷联惯导组合导航技术中存在着一个基本矛盾,即高精度组合系统的可靠性和实时性较差,而实时性和可靠性好的组合系统精度较低。比如,GPS RTK定位和捷联惯导的组合导航系统精度很高,但是随着定位位置与GPS基站之间距离的增加,系统的可靠性逐渐下降,且由于需要进行整周模糊度解算而实时性较差,因此不能应用于无区域限制的实时导航中;伪距和捷联惯导的组合导航系统具有很好的可靠性和实时性,适于导航应用,但精度较差。本文的研究目的之一就是通过GPS信息的合理应用以及新的组合技术来提高GPS和捷联惯导组合导航系统的整体性能。此外,惯性传感器的随机误差和捷联惯导的初始对准误差是组合导航系统的关键误差,本文的另一个研究目的就是通过新技术实现GPS辅助的这两种误差的最优补偿。围绕上述两个研究目的,本文主要完成了以下研究工作:1.以GPS载波相位观测量为基础,研究了载波相位时间差分观测量,并推导了其观测方程;探讨了载波相位时间差分观测量在导航与组合导航中的应用。误差分析表明载波相位时间差分兼具伪距和载波相位的优点,是一个非模糊的高精度的GPS观测量;导航试验研究表明由载波相位时间差分可以解算出毫米/秒量级的高精度速度;组合导航试验研究表明载波相位时间差分和捷联惯导的组合导航系统具有很高的短时精度,但是系统的位置误差存在着缓慢的积累效应。2.针对含有两种观测量且两种观测量之间测量噪声差异较大的最优估计系统,提出了使用双速卡尔曼滤波器把低噪声的观测量以高频的形式、把高噪声的观测量以低频的形式融入到最优估计系统中。通过分析双速卡尔曼滤波的误差协方差传播过程,发现双速卡尔曼滤波技术可以有效地隔离来自于不同观测量的测量噪声,另外双速卡尔曼滤波技术还可用于实现非同步观测信息的融合以及提高运算效率。3.以双速卡尔曼滤波器为数学工具,设计了基于载波相位时间差分、伪距和捷联惯导的紧组合导航系统。针对系统的实现问题,推导了双速卡尔曼滤波的系统方程(基于惯导误差方程)、高速卡尔曼滤波的测量方程(基于载波相位时间差分的观测方程)、以及低速卡尔曼滤波的测量方程(基于伪距的观测方程)。试验研究表明,提出的组合导航技术与经典组合导航技术相比,使导航的位置精度获得了改善,且明显改善了系统的速度精度、姿态精度和滑行性能。4.有色噪声对惯性传感器的性能有重要影响,为了在组合导航过程中在线补偿有色噪声引起的惯性传感器误差,需要对有色噪声进行建模。首先,针对单独的有色噪声,提出了从其功率谱密度函数推导其随机微分方程模型的一般步骤,并推导了几种常见有色噪声的随机微分方程模型。然后,针对多种有色噪声并存的情况,提出并证明了随机微分方程的等价性定理,此定理指出在宽平稳的意义下,多个随机微分方程可以等价地使用单一随机微分方程描述,并给出了此等价随机微分方程系数参数的确定方法。此定理解决了多种有色噪声共存时的等价建模问题,为有色噪声的在线补偿奠定了数学基础。5.设计了GPS辅助的惯性传感器随机误差在线补偿方案。在此补偿方案中,白噪声、量化噪声和有色噪声分别按照下列方法进行处理:(1)白噪声用以确定系统的过程噪声协方差矩阵;(2)通过修改惯导的误差方程,把量化噪声转化为等价的白噪声,并用以扩展系统的过程噪声协方差矩阵;(3)由等价性定理导出的多种有色噪声的等价随机微分方程模型用以扩展组合导航的系统方程。试验测试结果表明此在线补偿方案有效地补偿了惯性传感器的随机误差,明显改善了纯惯导系统的运行性能。6.为了减小大航向误差条件下捷联惯导动基座初始对准的模型误差,提出并实现了一种大航向误差条件下的捷联惯导动基座初始对准方案。针对此对准方案的实现问题,推导了相应的粗对准误差方程和测量方程以及精对准误差方程和测量方程。试验结果验证了所提出方案的优越性,通过与经典方案的试验结果相对比,发现所提出的初始对准方案明显改善了大航向误差条件下初始对准的精度和速度。7.为了减小捷联惯导动基座初始对准的观测量误差,设计了高精度的载波相位时间差分辅助的捷联惯导动基座初始对准方案。试验结果表明,载波相位时间差分辅助的捷联惯导动基座初始对准精度已经接近GPS PPK(Post-Processing Kinematic)定位辅助的捷联惯导动基座初始对准精度。更多还原

【Abstract】 For the conventional GPS/SINS integration techniques, there exists a basic dilemma, namely, the high precision integrated systems generally have poor reliability and real-time performances, and on the other hand, the systems with good reliability and real-time performances generally have low precision. For example, the integration of GPS RTK/SINS can be very precise, however, its reliability will become poor with the increasing of the distance from the GPS base station and its real-time performances are not good because of the necessity for the resolution of the integer ambiguities. So, generally, GPS RTK/SINS integrated system can not be used in real-time or wide-area navigation applications. As an opposite example, the integration of GPS pseudorange/SINS is suitable for navigation applications because of its good reliability and real-time performances, however, its precision is low. So, the first goal of this research is to improve the overall performances of GPS/SINS integrated system by rearrangement of the GPS information and by using new integration techniques. Besides, the stochastic errors of the inertial sensors and the initial alignment error of the SINS are two kinds of the most crucial errors, so the second goal of this research is to develop some techniques to optimally compensate both of them with the aiding of GPS. To accomplish these two goals, the following work has been finished in this research:1. A new GPS observable, incremental carrier-phase observable, has been derived based on GPS carrier-phase, and the corresponding observation equation for the incremental carrier-phase has also been derived. Furthermore, the applications of the incremental carrier-phase in navigation and integrated navigation have been discussed. Error analysis has shown that the incremental carrier-phase is an unambiguous and precise observable with the advantages of both pseudorange and carrier-phase. Navigation experiments have revealed that the mm/s level accuracy has been achieved in computing velocity from the incremental carrier-phase. Integrated navigation experiments have demonstrated that the integration of the incremental carrier-phase and SINS can obtain very high short-term navigation accuracy, while the position error will slowly accumulate with time.2. For the optimal estimation systems with two kinds of observables whose measurement noises are quite different with each other, a novel optimal estimation technique, dual-rate Kalman Filtering technique, has been proposed, and the relevant theoretical analysis has been done. The dual-rate Kalman Filter fuses the low-noise observable with high rate, and the high-noise observable with low rate into the optimal estimation systems. By analyzing the propagation of the error covariance, it has been found that the proposed dual-rate Kalman Filtering can effectively isolate the noises from different error sources, and at the same time, the dual-rate Kalman Filtering can be used to fuse the asynchronous observations from different sensors and can also improve the computation efficiency.3. By using the dual-rate Kalman Filter as the integration tool, a novel tightly coupled integration system based on the incremental carrier-phase, the pseudorang, and the SINS has been designed. To implement the above integrated system, the system equation for the dual-rate Kalman Filtering has been derived based on the SINS error equation, and the measurement equation for the high-rate Kalman Filtering as well as the measurement equation for the low-rate Kalman Filtering has also been derived based on the incremental carrier-phase and the pseudorange, respectively. Experimental tests have demonstrated that, compared with the conventional integration techniques, the proposed novel integration technique has improved the position accuracy, and dramatically improved the velocity and attitude accuracy as well as the coasting performance.4. Colored noises have important influences to the performances of inertial sensors, and to compenstate the errors of the inertial sensors introduced by the colored noises in GPS/SINS integration, it is necessary to model the colored noises. Firstly, for a single colored noise, a general procedure has been proposed to derive its stochastic differential equation model from its power spectral density (PSD) function, and the stochastic differential equations of several common colored noises have been derived. Then, for multiple concurrently existing colored noises, an equivalence theorem relating to the stochastic differential equation has been proposed and proved. The equivalence theorem states that multiple stochastic differential equations can be equivalently expressed as a single stochastic differential equation in the wide sense stationarity, and gives the formulas to determine the coefficients of the equivalent stochastic differential equation. The equivalence theorem is the basis of the equivalent modeling and on-line compensation for multiple concurrently existing colored noises.5. An on-line compensation scheme for the stochastic errors of the inertial sensors has been proposed with the aiding of GPS. In the compensation scheme, the white noise, the quantization noise and the colored noises are dealt with as follows: (1) the white noise is used to determine the covariance matrix of the process noise; (2) by modifiying the SINS error equation, the quantization noise is converted into white noise, and is used to augment the covariance matrix of the process noise; (3) the equivalent stochastic differential equation model for multiple colored noises, which is derived from the equivalence theorem, is used to augment the system equation of the integrated system. The results of the experimental tests have demonstrated that the proposed scheme has effectively compensated the stochastic errors of the inertial sensors, and as a result, dramatically improved the performances of the pure SINS.6. To reduce the in-motion alignment error of SINS introduced by the modeling error under the condition of large initial heading error, a novel in-motion alignment approach has been proposed for the SINS. To implement the above approach, the system equation and the measurement equation for the coarse alignment and fine alignment have been derive respectively. Experimental tests have shown the superiority of the proposed alignment approach, and compared with the conventional approaches, the proposed approach has dramatically improved the accuracy and speed of the alignment procedure.7. To reduce the in-motion alignment error of SINS introduced by the observable error, a novel in-motion alignment scheme has been designed with the aiding of high precision incremental carrier-phase. Experimental tests have indicated that the alignment accuracy of the SINS with the aiding of the incremental carrier-phase has almost approached the alignment accuracy with the aiding of GPS PPK (Post-Processing Kinematic) positioning.更多还原