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INS/DVL组合导航关键技术研究
中文摘要

在水下导航中,惯性导航系统(INS)/多普勒计程仪(DVL)组合导航系统凭借其完全独立性、自主性、隐蔽性和高精度等特点得到了广泛的应用。水下航行器在任务中要减少上浮的次数,以提高工作效率和隐蔽性,所以对水下导航系统的要求是尽可能长时间地保持高精度定位。INS/DVL组合导航系统通过航位推算实现位置参数更新,所以其定位误差会随着航行距离的增加而积累。本文以INS/DVL组合导航的关键技术为研究对象,旨在提高INS/DVL组合导航系统的精度,实现水下航行器的长航时自主导航。论文的主要内容和创新点如下: 一、使用基于Kalman滤波器的DVL测速误差标定方法,对DVL的安装误差、刻度因数误差和常值误差进行了标定,分析了在某些机动方式下无法实现标定的原因,设计了可以标定全部状态的机动方式。针对姿态角动态引入的DVL测速误差进行了建模,基于所建立的误差模型,提出了姿态角动态引入的DVL测速误差修正方法。所提出的方法全面考虑了姿态角动态对DVL测速精度的两种影响:①DVL发射信号时刻到接收信号时刻的时间段内自主水下航行器(AUV)的姿态变化引入的DVL测速误差;②DVL安装位置和AUV的浮心之间的杆臂引入的DVL测速误差。在所提出的方法中,推导了俯仰角动态、横滚角动态和航向角动态综合影响下的DVL测速误差修正方程,利用所推导的修正方程和INS/DVL系统提供的实时姿态信息对姿态角动态引入的DVL测速误差进行修正。半实物仿真实验的结果验证了所提出的修正方法可以有效修正姿态角动态引入的DVL测速误差。 二、针对DVL辅助下的INS动基座初始对准技术进行了研究,设计了惯性系粗对准和基于Kalman滤波器的精对准相结合的对准方法,可以在任意初始失准角条件下实现DVL辅助下的INS动基座高精度对准。通过对可观测性解析分析方法进行改进,提出了基于先验知识的可观测性解析分析方法,使用该方法分析并计算了匀速直线运动轨迹下DVL辅助INS对准的极限精度,明确了制约对准精度的因素,根据分析结果,设计了能够提高对准精度的机动方式。仿真实验的结果表明,通过合理地设计用于对准的机动方式,可以提高DVL辅助下的INS对准精度。 三、针对INS/DVL的紧组合方式进行了研究,推导了紧组合方式下INS/DVL组合导航系统的模型。基于INS/DVL紧组合方式,提出了DVL受限数量波束量测可用条件下的组合导航方法,该方法应用于在特殊情况下DVL只有受限数量(小于3条)波束量测可用的情况。在这些情况下,DVL不能解算出AUV的速度,导致INS/DVL松组合方式没有外参考速度,无法进行组合导航。使用所提出的方法,INS/DVL组合导航系统可以在DVL最少只有一条波束量测可用的条件下保持高精度导航,该方法的有效性通过半实物仿真实验进行了验证。最后,本文针对INS/DVL组合导航系统的定位精度进行了分析。 关键词:INS/DVL组合导航 DVL误差修正 可观测性分析 紧组合方式

英文摘要

Inertial Navigation System (INS)/Doppler Velocity Log (DVL) integrated navigation system has been widely used in underwater navigation due to its complete independence, autonomy, concealment and high precision. Underwater vehicles need to reduce the surfacing times during the missions to improve their efficiency and concealment. Therefore, underwater vehicles require the navigation system to maintain high accuracy positioning as long as possible. INS/DVL integrated navigation system updates the position parameter through dead reckoning method, therefore its positioning error will accumulate with the increase of traveled distance. In this paper, the key technologies of INS/DVL integrated navigation are studied to improve the accuracy of INS/DVL system, thereby realizing the long term autonomous navigation of underwater vehicles. The main contents and innovations of the paper are listed as follows. 1.The installation error, the scale factor error, and the constant error of DVL are calibrated by utilizing the Kalman filter based calibration method. In the calibration process, the reason why the calibration cannot be achieved in some maneuvering modes is analyzed and maneuvering modes that can effectively achieve calibration are designed. The model of the DVL measurement error introduced by attitude dynamics is established. Base on the established error model, a correction method for DVL measurement error introduced by attitude dynamics is proposed. In the proposed method, the two effects of the attitude dynamics on the accuracy of DVL measurement are fully considered. The two effects are: ①the DVL measurement error introduced by the attitude change of Autonomous Underwater Vehicle (AUV) between the DVL signal transmission and reception instant; ② the DVL measurement error introduced by the lever arm between the DVL installation position and the buoyant center of the AUV. In the proposed method, the correction equation for DVL measurement error indroduced by pitch dynamics, roll dynamics and heading dynamics simultaneously is derived. By utilizing the derived correction equation and the real-time attitude imformation from INS/DVL system, the DVL measurement error introduced by attitude dynamics can be corrected. The performance of the proposed method is examined through semi-physical simulation experiments. 2.The technology of DVL-assisted INS initial alignment under moving base conditon is studied. The inertial frame coarse alignment method and the Kalman filter based fine alignment method are used to realize the DVL-assisted INS initial alignment from arbitrary initial misalignment angles. A prior knowledge based observability analysis method is proposed by improving the original observability analysis method. By using the proposed method, the ultimate accuracy of DVL-assisted INS fine alignment under a uniform linear trajectory is analyzed and calculated. The factor that limit the accuracy of fine alignment is determined. Based on the analysis result, a maneuvering mode which can improve the accuracy of fine alignment is designed. Simulation results show that the accuracy of the DVL-assisted INS fine alignment can be improved by designing the maneuvering modes used for fine alignment reasonably. 3.The INS/DVL tightly coupled approach is studied and the model of INS/DVL tightly coupled navigation system is established. Based on the tightly coupled approach, a method for INS/DVL integrated navigation with limited DVL beam measurements is proposed. The proposed method is used for the cases that DVL has only limited (less than 3) beam measurements under special circumstances. In these cases, DVL cannot calculate the three-dimensional velocity of the AUV. As a result, the INS/DVL loosely coupled system cannot operate because there is no external reference velocity. The proposed method is based on the INS/DVL tightly coupled approach and gives countermeasures for the cases that DVL only has limited beam measurements. Semi-physical simulation experiments are carried out to evaluate the proposed method and the results show that the INS/DVL integrated navigation system can maintain high accuracy even when the DVL has only one beam measurement by ultilzing the proposed method. Finally, the positioning accuracy of INS/DVL integrated navigation system is analyzed. Key Words: INS/DVL integrated navigation, DVL error correction, observability analysis, tightly coupled approach

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