基于MEMS IMU的GNSS RTK/INS紧组合定位分析

Tightly coupled GNSS RTK/INS integration positioning based on MEMS IMU

本文针对复杂动态的城市环境自动驾驶规模化应用需求,提出惯性单元辅助RTK快速收敛的自动驾驶低成本、高精度定位方法。使用MEMS IMU M39和战术级IMU Pos320,通过对多组实测车载数据进行仿真中断,得到INS位置漂移误差、模糊度收敛时间、模糊度固定正确性指标,再对无惯导辅助、M39辅助模糊度固定和Pos320辅助3种情形下的模糊度固定时间和定位精度进行了统计和分析。结果表明,M39在GNSS中断5 s时可辅助RTK实现模糊度瞬时固定,中断时间为10 s时可以将RTK模糊度收敛时间压缩至1/4。MEMS IMU的加入使得RTK模糊度固定错误个数显著下降,10 cm以内高精度定位占比由62.25%提高至98.44%。试验验证了MEMS IMU辅助RTK能够加快模糊度收敛速度,提高了其在自动驾驶导航定位应用中的精度和可靠性。

In order to improve the poor GNSS positioning stability in complex environment,a low-cost and high-precision positioning method with IMU assisting RTK for autonomous driving is proposed.MEMS IMU M39 and tactical IMU Pos320 are used in simulation experiments.Through simulating interruption of multiple groups of measured vehicle data,INS position drift error,ambiguity fixing time and fixing accuracy are obtained.The ambiguity fixing time and positioning accuracy under three conditions of no inertial navigation assistance,M39 assistance and Pos320 assistance are statistically and analyzed.The results show that M39 can assist RTK to achieve instantaneous ambiguity fixing with 5 s GNSS outage.When the outage is 10 s it still can reduce the convergence time of ambiguity to 1/4.Also,with assistance of MEMS IMU,the number of incorrect ambiguity is significantly reduced,and the proportion of high-precision positioning within 10 cm is increased from 62.25%to 98.44%.Experiments show that MEMS IMU assisted RTK can accelerate the speed of ambiguity fixing and improve the accuracy and reliability of navigation and positioning in autonomous driving.