School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China.
China National Institute of Standardization, Beijing 100191, China.
Sensors (Basel). 2023 Mar 31;23(7):3662. doi: 10.3390/s23073662.
The integrated system with the strapdown inertial navigation system (SINS) and the global positioning system (GPS) is the most popular navigation mode. It has been used in many navigation fields. Before the integrated system works properly, it must determine the initial attitude for SINS. In SINS/GPS-integrated systems, the navigational velocity can be used to carry out the initial alignment when the system is installed in the in-motion vehicle. However, the initial velocity errors are not considered in the current popular in-motion alignment methods for SINS/GPS integration. It is well-known that the initial velocity errors must exist when the initial velocity is obtained from the GPS outputs. In this paper, an improved method was proposed to solve this problem. By analyzing the original observation vectors in the in-motion coarse alignment method, an average operation was used to construct the intermediate vectors, and the new observation vector can be calculated by subtracting the intermediate vector from the original observation vector. Then, the initial velocity errors can be eliminated from the newly constructed observation vector. Thus, the interferences of the initial velocity errors for the initial alignment process can be suppressed. The simulation and field tests are designed to verify the performance of the proposed method. The tests results showed that the proposed method can obtain the higher accurate results than the current methods when the initial velocity is considered. Additionally, the results of the proposed method were similar to the current methods when the initial velocity errors were not considered. This shows that the initial velocity errors were eliminated effectively by the proposed method, and the alignment accuracy were not decreased.
组合惯导系统（SINS）和全球定位系统（GPS）的集成系统是最流行的导航模式。它已被广泛应用于许多导航领域。在集成系统正常工作之前，必须确定 SINS 的初始姿态。在 SINS/GPS 集成系统中，当系统安装在运动载体上时，可以利用导航速度来进行初始对准。然而，当前流行的 SINS/GPS 集成动基座对准方法中并没有考虑初始速度误差。众所周知，当从 GPS 输出获取初始速度时，必然存在初始速度误差。针对这一问题，本文提出了一种改进方法。通过分析动基座粗对准方法中的原始观测向量，采用平均运算构造中间向量，并通过从原始观测向量中减去中间向量来计算新的观测向量。这样可以从新构造的观测向量中消除初始速度误差。因此，可以抑制初始速度误差对初始对准过程的干扰。设计了仿真和现场测试来验证所提方法的性能。测试结果表明，当考虑初始速度时，与当前方法相比，所提方法可以获得更高的对准精度。此外，当不考虑初始速度误差时，所提方法的结果与当前方法相似。这表明所提方法可以有效地消除初始速度误差，并且对准精度没有降低。
