基于单轴旋转INS/GPS组合姿态误差观测的垂线偏差测量方法

Measurement of dynamic vertical deflections by observing attitude errors of single-axis rotation INS/GPS system

单轴旋转INS/GPS组合导航系统的姿态误差直接受垂线偏差的影响,因此利用对单轴旋转INS/GPS组合的姿态误差观测也可实现垂线偏差的估计。首先,利用INS中的三个激光陀螺构建了激光陀螺组合体(LGU)并进行自主姿态测量,以LGU作为姿态基准以获取INS/GPS组合的姿态误差。然后,建立垂线偏差测量的观测方程和状态方程。最终采用Kalman滤波/平滑算法同时实现垂线偏差和其他系统误差的最优估计。通过对状态变量精确、合理地建模,并利用全球重力模型补偿垂线偏差信号的低频分量,从而实现垂线偏差与系统误差的解耦。通过仿真验证了该方法的可行性,仿真所用的航迹由实测数据生成。仿真结果表明该方法能够有效地测量垂线偏差的高频扰动量。由于该方法的测量精度依赖于所采用的陀螺性能,采用角随机游走较小的陀螺可以获得较好的垂线偏差测量结果。船载实验结果表明,该方法测量得到的垂线偏差数据重复性精度优于0.5″。

Since the attitude errors of INS/GPS integrated system are directly related to deflections of the vertical （DOVs）, it is expected that DOVs can also be estimated via the observation of INS/GPS attitude errors. In this paper, a laser gyroscope unit （LGU） is constructed by three laser gyroscopes of the INS, and used as an attitude reference for calculating INS/GPS attitude errors. Then, the observation equation and state-space equations for DOV measurement are accurately modeled. Finally, the DOVs and systematic errors are simultaneously estimated by a Kalman filter/smoother. The DOVs and systemic errors are decoupled since the state-space variables are accurately and properly modeled, and the long-wavelength components of DOVs are well compensated by a global gravity model. The feasibility of the proposed method are validated by simulation. Simulation results also show that this method can measure the high-frequency disturbances of DOVs efficiently. As the measurement accuracy of this method depends on the performance of gyroscope, a better accuracy of DOV measurement can be achieved when the gyroscopes with low angular random walk are adopted. The shipborne experiment results show that the repeated accuracy of the DOV measurement method is better than 0.5＂.