333 / 2023-10-15 23:55:03

基于IGGIII抗差状态估计的部分模糊度固定改进算法

抗差状态估计,部分模糊度固定,成功率指标法,条件方差矩法

GNSS monitoring technology is widely used in the field of deformation monitoring because of its all-weather, all-day and high precision.The key to GNSS high-precision positioning lies in the correct solution of carrier phase integer ambiguity. In mine slope monitoring, GNSS signals are susceptible to high occlusion, multipath and other factors, resulting in a large number of gross errors in observation data. Under the interference of gross errors, the statistical characteristics of carrier phase observations will change, and then the accuracy of floating-point ambiguity will be affected by the propagation of parameter estimation, which will eventually lead to the deterioration of ambiguity fixing rate and the reliability of positioning results.In view of the above problems, this paper proposes an improved partial ambiguity fixed algorithm based on IGGIII robust state estimation.This method starts from the observation domain and introduces an improved robust state estimation algorithm. Firstly, the standardized residual of the observation value is constructed. Combined with the hypothesis test theory and the 3 criteria, the observation value is divided into reliable observation value, suspicious observation value and abnormal observation value. At the same time, based on the reliability of the maximum standardized residual, different variance expansion functions are used to update the random model to reduce the probability that the observation value without gross error is mistakenly reduced, thereby improving the accuracy of floating-point ambiguity. Considering that the robust state estimation algorithm cannot completely eliminate the influence of gross errors, in order to avoid the influence of residual errors on the subsequent integer ambiguity resolution, an improved partial ambiguity resolution method is introduced from the ambiguity domain. The ambiguity subset is screened according to the conditional variance matrix method, and a step-by-step combination verification method considering the strength of the observation model and the distinguishability of the ambiguity candidate solution is proposed to further improve the reliability of ambiguity resolution.The experimental results show that compared with the full ambiguity fixing method, the improved partial ambiguity fixing algorithm based on IGGIII robust state estimation can significantly improve the ambiguity fixing rate, and the three stations are increased by 5.9 %, 52.7 % and 48.0 % respectively. At the same time, compared with the traditional Kalman filter algorithm, the improved robust state estimation algorithm based on IGGIII improves the accuracy of floating-point fuzzy parameters, greatly improves the ambiguity fixing error, and significantly improves the GNSS positioning accuracy. The horizontal direction is better than 1cm, and the elevation direction is better than 2cm.